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IS 3177 : 1.999 ReaffinDed 2004

J fl f 117 rtCfj

. i 3lffiClT fmTqft em;ft~ ~ ~ t R ~ c p T

gff ?7 p R T ~

ndian StandardCODE OF PRACTICE FOR ELECTRIC OVERHEAD

TRAVELLING CRANES AND GANTRY CRANESOTHER THAN STEEL WORK CRANES

Second Revision

Second Reprint SEPTEMBER 2008 Including Amendment No . J 2

ICS 53.020.20

SIS 1999

U R E U O F I N D I N S T N D R D S

M A N A K B H AVA N 9 B A H A D U R SHAH Z A FA R MARG

N EW E L I ~ I

2 pril 1999 . Price Group 15

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AMENDMENT NO. 1 DECEMBER 2000TO

IS 3177: I CODE OF PRACTICE FOR ELECTRICOVERHEAD TRAVELLING CRANES AND GANTRY

CRANES OTHER THAN STEEL WORK CRANES S.COIIII Rnisiola )

[ Page 2, claus 3.Z b - Substitute th e following fo r th e existiag matter:

lib Ambient temperature should be o tel C aDd i f tbe service conditionsthose beyond this, suitable derating acton .M U be applied.

Pllge 3, Fig. 2 ) - Read dimeasion L fo r dimension 1.

(Page S Table 1 - Substitute 1 .4 or 150 in col 2 against M7 .

(Page S clause 7.3.1 ) - Substitute 7.2 for I .z under Rbi.

( Page 9, clause 1.1. ) - Substitute the following for th e existiDg matter:

For loads up to and i nd ud in g 5 0 t, Shank type plain books be used unlessotherwise specified by tbe purchaser. For 1000ds of SO t and over, boob of Ramshom type or triangular lifting eyes are to be preferred where there is chance offouling of b oo k a nd the risk of displacement of load during boistiDg and forlowering e type hook shall be used. Hook witb book latch is to be providedwith closing fingers to prevent slippage of load. However an option ca n be givento the purchaser on wbetber book is to be provided with closing fingers or booklatch. In tbis case the biage lug fo r the closing- finger shall be forpd with tbebook. Th e finger shall be capable of taking load equal to 1.5 times of the weightof book block without distortion in accordance witb IS 13870 (part I).

P a ~10 , clause 1.3.J ) - Subst itu te the following for Zp:~ =minimum practical co-efficient of utilization. For DOrm. ) condition Zp shall

be taken equal to 6 for M7 aDd M8, Zp 4 for Ml to M6.(Page 11, clause 1.4.6 apu,lUItioll/or d ) - Substitute dwmcter of the

rope, in mm for the exis t i . matter.

(Page 11 , claus 1.5. , st JNlNlgrtlplt ) - Substitute 1.4.6 for 7 A-

11-51 BISINDI2008

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Amend No.1 to IS 3177 : 1999

1.5 W

Page 13, clause 8.6.6 - Delete D =a

substitute the following for the existing formula:

Pmean x Cdr x CsC 5 a x e x Ca p

or, and

whereD =

P mean =A = d f = h =

Csf

C sp

tread diameter of t he whee l in mm ;

mean wheel load in newtons;

useful width of rail;

duty factor for the appropriate mechanism class as defined in 7 4 3;

hardness factor for the wheel material. Fo r values, refer Table 9.Here wbeel hardness Bh w as calcula ted in 8.6.3 sball be used evenif wheel rim if hardened more for longer wheel life;

safety factor depending on the ma te ri al used as def ined in 7 .4 .3 ; and

co-efficient depending on the speed of rotation of t he wheel as

defined in Table 10. Page 16, clause 8.7.1, second paragraph - Delete steel from tbe first

line.

Page 17, clause 8.8.2 - Substitute o r for o f in first l ine of sentence.

Page 17, clause 8.8.3 - Substitute the following for tbird paragraph:

T he gearbox mounting shall be machine cut , sea ted and positively located onmachined surface.

Page 21 , Table 12 - Substitute 240 fo r 6 0 in column 3 against a e Magnets .

Page 25 , clause .1 .2.2, ITSl paragraph third sentence - Substitute o rfo r ;of .

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Amend No.1 to IS 3177 : 1999

( Page 25, clause l ~ ) - SutRitute the follo\ving for the first serseree:

The provision of overloed protection sh be with adjustable inverse time log overtoadrelease.

Page ~ clause IS.J.4,{ust paragraph - ~ t tIE last serseree,

[Page 31 clou se 20.1 (a) n i (b)] -SutEtitute ( ]ass for sizes ,

Page 32, clause 1Z.3) - SutRitute 20 or 19 .

Page 34, Table 17 ) - SutRitute wilhoulawu for wich CO Ja in column 2 URIer IP54.

[Page43 clause 21.3 (a), btd test ) -Subititute 50 for 5 .[Page43, clause 21.3 (b), load }-SutNitute 100 fa- 125. .

Add 28.J Load T est (c) Losd the nntion with 125 pereera o f rated capecity, lift the btdfor 1M r ~ and then lower bad .

( Page clause ) - Subititute Cd( or Cc.- .

Pages 52awJ53,cIauseC.1 I n factoredf .substinne 7A3 for 6.4.3 .

Page 53 Table B - SutRitule the table for tbe existing;

Table 208 Reamtmended Cyclk Duration Factor and Start ing Class(Clause e-n

MecbaoiYa Class Duty Cycle Numbft- e c o m m ~ n d e dCycUc S lartinc Clau ( C )of Cyclic Class (C) Dunt ion Factor Equivalent

Cydft hour, percent percent S larts/bour

M t Upto5 25 90cycles 25

M2 Up lo 25 90cycles 2S

M3 10 to 15 25 150cycles 40

M4 16 to 20 2S 150cycles 40

MS 2110 30 25/40 tSOI3OOcycles 60

M6 31to 40 40 300cycles 60

M7 41 to SO 60 30 0cycles 100

M8 5110 60 60 3 6cycles 100

I 5 BISIND/2008 3

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( Pages 53 an d 54, A n n a C, clause C Z z - Fo r explanation of T, deletelast two lines after the explanation and substitute Table 21B with tbe following:

Table ZIB Values or Service Factors ItJuu Cl. )

Briel. Serrice F.do r Trolley S e n k e

Without Pluuil l l WithP lVng F.ctor0.95 1.00 1.06

( Pag e 54, clause C-Z.l Substitute 7.4.3 for 6.4.3 under d and 7.3.1 [o ro .3. 1 (under Rw1

M ED 1 4

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M E N D M E N T NO 2 J U LY 2003TO

IS 3177: 1999 CODE O F PRACTICE F O R E L EC T R ICOVERHEAD TRAVELLING CRANES AND GANTRY

CRANES OTHER THAN S TE EL W OR K CRANES

Second Revision

[ Page 10, clause 8.3.2 s ee a ls o mendment No I ) J - Substitute thefollowing for Zp:

Zp = minimum practical coefficient of utilization. For normal condi tion Zpshall be taken equal to 3.5 for M I to M8 other than hot mill dutycranes. Zp shall be taken equal to 5 for hot mill duty cranes .

r Page 13, clause 8.6.6 see a lso mendmen t No I ] - Substitute thefollowing fo r the existing formula:

Pmean x C df x Cs f

5 a x Ch h x ~ s

Page 54 , nnex C ) - Substitute explanation for notation for existing:

= mechanica l e ff ic iency of gearing. For spur and helical gears,efficiency to be taken as 0.95 pe r reduction. Fo r hardened and groundgears, efficiency to be taken as 0.985 per reduction.

M ED 14 )

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Cranes. LiftinS Chains.DeI Related Equipmaall Sectioaal oauniaee HM O 14

FOR WOR

This Ind ian Standard second Revision) was adopted by the Bureau of Indian Standards, af ter the draftfinalized by the Cranes, Lifting Chains and Related Equipments Sectional Committee had been approved bythe Heavy Mechanical Engineering Division Council.

This standard covers mechanical and electrical aspects related to design, manufacture, erection an d tcstingof electric overhead travelling cranes an d gantry cranes used in hazardous areas like Ga s Group 2c. Electricalmotors an d electric thruster unit for brakes, limit switches, Pendant push button station an d panels shall beof flameproof suitable for Gas Group 2c).

An attempt is made here to include provisions:

a) to bring this standard in l ine with the International Standards,

b) to keep higher factor of safety for hoisting mechanisms compared to t ravel l ing mechanisms whichmay reduce cost of cranes without sacrificing safety, an d

c) to help standardization, as far as possible, relating requirements for components to basic duty factorfor class of mechanisms.

While preparing this standard assistance has been derived from various Indian, British, DIN, FE M an d ISOstandards to bring this standard in l ine with the International Standards.

As followed in th e Internat ional Standards, s t ructural provisions for cabin, walkways an d means of accessare not included in this standard. It is proposed that the same shou ld be added in IS 807. In line with thisstandard an d new classifications now adopted, IS 807 should be modified. Provisions in IS 807 for allowablestresses, deflection criteria, wheel base to span ratio an d tolerances on spans, wheel alignment, etc, be modifiedto bring the-standard in line with International Standard.

The new classification of cranes now coming into effect an d the classification presently in use ca n approximatelybe compared as follows:

Old Equivalent w Classification

I M3

II MS

M7

IV M8

For the purpose of deciding whether a particular requirement of this standard is complied with, th e final value,observed or calculated, expressing the resul t of a test or analysis, shall be rounded of f in accordance withIS 2 : 1960 Rules for rounding of f numerical values revised) . Th e number of significant places retained in

the rounded of f value should be the same as that of th e specified value in this s tandard.

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IS 3177 : 1999

Indian Standard

CODE OF PRACTICE FOR ELECTRIC OVERHEADTRAVELLING CRANES AND GANTRY CRANES

OTHER THAN STEEL WORK CRANES Second Revision

1 SCOPE

This codecoversmechanical, electrical, inspection andtesting requirements relating to the design,manufacturing and erection of electric overheadtravelling cranes portal andsemi - portal cranes singlegirder, double girder or mono-box type s

Fig. I . It does not cover steel work cranes whichare coveredin IS 4137 : 1985 and newclassificationfor the crane as a whole, which has been defined asfrom No. I A2, A8 and crane mechanism hasbeendefinedas from Nos. MI, M2, ..... M8 accordingto IS 13834 Part 1 : 1994.

2 REFERENCES

2.1 The Indian Standards listed in Annex Farenecessary adjuncts to this standard.

1A Top Running Crane Double Girder

1B op unning Crane Single Girder

1C Semi Goliath Crane

1D Goliath Crane With Cantilevered Extension

I:IG. I rYPICAL ~ R N ETYPES Continued

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IS 3177: 1999

E Offset Crab Crane

FIG TYPICAL CRANE TyPES

SECTION GENER L

3 TERMINOLOGY

3.1 General

For the purpose of this standard the definitions givenin IS 13473 Part 1 and following text shall apply.If there are common terms, the definitions given inthis standard shall prevail.

3.2 Normal Serv ice Cond i tion

Normal service condition shall satisfy the followingconditions.

a Indoor and outdoor applications should withnormal air of normal humidity and frcc fromcontamination.

b Ambient temperature should be between and 40C and if the service conditions thosebeyond this, suitable derating factors shallbe applied.

c Altitude should not exceeding I 00 0 m abovemean sea level.

4 TECHNICAL INFORMATION TO BEPROVIDED

4.1 Information to be Provided Before Finalizin2 ttie Order

4 Information to he Provided hy the Purchaser

Allthe necessaryinformation regarding the conditions

2

under which the crane is to be used, together with theparticulars laid down in Annex A shall be suppliedwith the enquiry or order.by the purchaser to enablethecrane manufacturer toofferthe most suitable craneand equipment to satisfy the duty requirements andservice condi tions The enquiry shal l also beaccompanied with a clearance diagram.

4 2 Information to Provided y th

Manufacturer

The manufacturer shall supply with the tender alongwith the requisite information like regarding theconstruction of the crane according to the particularslaid down In Annex B unless agreed otherwise bythe purchaser.

4.2 Information to be Provided Prior to Installationan d Commissionin2 of th e Crane

The manufacturer shall provide the followinginformation while commissioning of the crane:

a General arrangement drawings showing allleading dimensions and Installation detailswhich were given in Fig. 2A and 28rcspecuvcly;

b Circuitand wiring diagram;

c Operating and maintenance Instructions:

d Recommended spare parts list:

e Testcertificate:

f Details of all brought outs such as motors.

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x

HOOKS\ . . . - -

y

03 0 OPEN235 ENCL

O 790 FORENCLOSED CAB

HPAN

50 ~min

t - f

I . A8

I t i

E

4-. r

I / II

E 2 2030 46

C N 0 min

R TE LOSPAN A 8 C 0 E G H J K L X Y

2A E. O. T. Clearance DiagramFIG 2 DIMENSIONS KlR E. O. T. CLEARANCE AND GAr rrRY CRANE CLEARANCE DIAGRAM ontinued

-

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A Q

v

r

~ 0 3 J I

b I I I -rII

II

~ -

I KC . RIII c. I .

- - .r, t.--. E~ l 4 ~

F

.J

M

N

S

II I

I-- IIIII

) I; \J i L

~ r -0 J f

0

. i::P

L L

-~

R ATED LOA D SPAN A B C 0 E F G H J K L M N P Q R S T U

Gantry Crane Clearance Diagram

FIG 2 DIMENSIONS fUR E O T CLEARANCE AND G NfRY CR NE Q E R NCE DIAGRAM

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gear box, brakes, etc, along with theirmanufacturer s name model number addressetc; and

g) Should also provide full details of the wireropeused such as construction, length, gradeand manufacturer s name, etc.

5 IDENTIFICATION AND LOAD INDICATION

5.1 Both sides of the crane shall bear one or moreplaques along with permanent inscription on whichthe following shall be inscribed:

a) Manufacturer s name and trade-mark,

b) Th e safe working loads of each independenthoist of the crane, and

c Purchaser s crane code number if requiredby the purchaser).

These plaques should be readilylegiblefrom the groundfloor level or operating level and shall be accessiblefor maintenance.

5.2 A small plaque shall be located in a prominentposition in the cab or at the approachable portion ofthe crane bearing the following inscription:

a) Manufacturer s nameand trade- mark,

b) Manufacturer s serial number,

c) Yearof manufacture, and

d) Safeworking load.

6 CLASSIFICATIONThe classification of the crane as a whole and of eachmechanismshall be based on the informationprovidedby the purchaserand shallbe determinedin accordancewithIS 13834 Part I) and IS 13834 part 5) respectively

NOTES

1 The classification of the individual motions of a cranemay not necessarily be the same as those of cranestructure. The classification of one motion of a cranemay differ from that of another motion of the samecrane.

2 In the case where a crane mechanism is required toperform a duty that falls beyond the Group ClassificationM8, either the mechanism shall be designed for higher

hook load or other parameters shall be changed so thatit satisfies requirement for the Group Classification MS.

SECTION 2 MECHANICAL

7 DESIGN OF CRANE MECHANISM

7.1 General

The design of the component parts of the mechanismrelating toeach crane motion shall be included with

5

IS 3177 : 1999

due allowance for tbe effects of the duty which themechanism will perform in service. Thedesign of thecomponent pans shall be in accordance with theprovisions given in this section.

7.2 Impld Factor

The impact factor applied to the motion of the hookin a vertical direction covers inertia forces includingshock. In calculating the live loads in thecomponentsof the mechanism the rated hook load shall bemultiplied by the impact factor, given in Table 1for various classes of mechanismwhich were givenbelow:

Table 1 Impact Factor for Structural Design

Group CI lific tion of Imp ct .... ctort he M ec ha ni sm

MI 1 06

M2 1.12

M3 I 18

M4 1.25

M5 I 32

M6 1.40----

M7 1 50_.

M8 l 50

7.3 Loadings to be Considered in th e Desi2D ofMechanisms

7 3 Loads

The following loadings shall be taken into accountwhen designing a mechanism and its components:

d a loadsdueto the deadweightof the mechanismor componentand dead weight of those partsof the crane acting on the mechanism or thecomponent underconsideration.

R h loads due to the weight of the hook loadwith reference to Fig. 3 and also it IS definedas SWL of the hook.

u = loads due to the weight of the hook loadincreased by the impact factor given in 8.2.

= dynamic loading arising from the acceleration or braking of the motion andfrom skewing interaction between thecraneand track. These loads include those loads

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IS 3177 : 1999

SAFE WORKING

LOAD OF CRANtSAFE WORKING LOAD orLIFTING ATTACHMENT

LIFTINGATTACHMENT

SLINGS L F TING MAGNETBEAM

GRAB BUCKET

CRANE LOADS

FIG. ILLUSTRATIQtoI OFTVPlCAL ATTACHMENI S IN R El ATlONTO S F WORKING LoAD

due to the below said reasons:

a inertia of the mechanism, associatedcrane parts and hook load,

b its prime mover and brakes, and

c concurrent operation of other motions,etc, as applicable.

Rr= loads arising from frictional forces.

RwI loads due to th e service wind actinghorizontally in any direction where appli-cable according to IS875 Part 3 .

RW l = loads due to the out of service wind actinghorizontally in any direction where appli-cable according to IS 875 Part 3 .

R = loads due to collision with end buffers.

7 3 2 Loading Condition nd Load Combinations

Each mechanism of the crane shall be designed tooperate satisfactorily under the most unfavourablecombination of loadings that can occur under different

conditions and that could also actually occur inpractice.

Case I Normal service without wind where craDecapacity equal to R

a Vertical motion: hoisting or lowering

I R d Rh Rm R

2 s Rhl

6

b Horizontal motion: traverse or travel

Rd Rh Rm R r

ue D ormallemcewitb wind

a Vertical motion: hoisting or lowering

I R d Rh Rm R RW1

2 R d + Rtu RW1

b Horizontal motion: traverse or travel

Rd Rh Rm R RW1 ue m Crane out or serviee

a Vertical motion : hois ting or lowering notapplicable.

b Horizontal motion: traverse or travel

Rd w2

ue IVEueptionalloadingcondition

The combination of loads to be considered for thiscase of loading will depend upon the type of crane,application and the crane motion. Account shall betaken of any loading condition that are known to applybut which are not covered under the other three casesof loading. A few cases of exceptional loading areas follows:

a Loads due to col lision of cranes with eachother or with end stoppers that isbuffer loads.

b Loads due to testing of cranes.

c Erection loads.

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d) Loads due to the maximumloadthat the motorcanactuallytransmit to the mechanism whilestarting,stalling ordue tohigher actual power.

7.4 Delign Proeedure

7.4.1 General

Mechanism components shall be proportioned bychecking that they have adequate safety againstbecoming unserviceable as a result of a singlecombinationof extreme loading conditions causingfracture, bendingor other type offailures.Theyshallalso be checked whenever appropriate againstfatigue deflection or overheating. In thisconnection,consideration shall be given to the consequencesoffailure. Forexample, failure in hoisting mechanismcomponent is usually more dangerous occurrencesthan failure of a horizontal motion mechanism.

7.4.2 Basis Design

Mechanismcomponents are checked depending onthe ultimate strength by verifyingthat the calculatedstressdoesnot exceed a permissiblestressdependenton the breaking strength of the material used.

7.4.3 Permissible Stress

Mechanism componentshall be checkedfor strengthunder ase I, II and IVloadingconditions andloadcombinations specified in 7.3.2. The value of thepermissiblestress F is given by following formulawhereunit of stress was defined as Nzmm :

F where

F ult = ultimate tensile strength of the material.CdC= dutyfactorfor the appropriatemechanism

class. For the values referTable 2

CbC= basic stress factor corresponding toeach case of loading. For the valuesrefer Table3.

CIC safety factor depending on the materialused. For the values refer Table 4.

7.4.4 Relation between Calculated and PermissibleStresses

Accordingto the type of loading to be consideredthe following relations shall be verified:

a) ure tension 1.2SIt cr,b) Pure compression.fc s F

7

IS 3 17 7 : 1999

Table 2 Valuesof ~ c i e a tc Clause 7.4.3

Group Fo r Mecha For For Mechani.mClalilf l nlam Mecha- Used for Vertical

cation U.ed for nlam Motion withof Horilontal Used for People or While

Mecha- Motion Vertical Handlinenlam Motion Dangerou. for

Eumple MoltenMetal. HighlyRadio-Active or

CorresslveProduct.

MI 1.00 1.18 132

M2 1.06 1.25 140

M3 1.12 13 2 1.50

M4 1.18 140 16 0

M5 1.25 1.50 1.70

M6 132 160 18 0

M7 1.40 1.60 19 0

M8 1.50 1.70 2.00

Table 3 Values of Co-efficient, Cbl Clause 7.4.3

Case of Loading I U III and IV Cbl 3. \ 5 2 5 2.0

Table 4 Values of Co-efficient, CClause 7.4.3

For ordinary grey cast iron or for cast or 1.25

forged components where blow holes orinternal cracks can notbe detected.

For mild steel Fe 310 and Fe 410 1.12

For other materials Fe 44 and Fe 57, etc. 1.00

c) Pure bendingeither compressionor tension

or S F

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r;

IS 3177 : 1999

d) Combined bending and tension

l .25f+L ,FI

e) Combined bending and compression

+ .F.

f Pure shear 3f s f, .g) Combined bending, tension and shear

h) Combined bending, compression and shear

where

calculated axial tensile stress,

r calculated axial compressive stress.c

J - calculated maximum tensile stress due tobt -bending about both principal axes,

f h c = calculatedmaximumcompressivestress dueto bending about both prrncipal axes. and

f = calculated shear stress.7.4.5 Checking fo r Fatigue

7.4.5.1 General

Where it is necessary to check a component forfatigue, recognized techniques available forcalculation of fatigue properties shall be used. Thechoice of the methods used shall be left to themanufacturer, however he shall specify the origin ofthe methods to beadopted ifasked bythe customer.

7.4.5.2 Loading condition

Case I ofloading condition as specified in 7.3.2 shallbe used as the basis for all fatigue checks.

7.4.5.3 Factors affectingfatigue strength

For any component, the magnitude of the fatiguereferencestress depends upon the following factors

a) the total number of stress cycles during theservice life of the component n

b) the type of stress cycles that is, degree ofstress fluctuation).

8

c) the quality of the material.

d) the size of the component,

e the surface fmish of the component,

f theconfigurationofthe individual detailsunder

consideration.g) miscellaneous effects such as the effects of

corrosion, residual stress, electrolyticplatmg.metal spraying. etc, where under certainconditions reduce the permissible fatiguestress. Annex B givesa method forcalculatingthe fatigue reference stress P which takesaccount from the factor a) to g) aboveandincludes allowance giving a 90 percentprobability of survival.

NOTE - A check lor fatigue need not be made the cases where experience shows that the ultimates tr en gt h check as per 7 4.3 IS sufficient

7 5 ~ t r e s s e s

The followingcharacteristics shall be determined foreach type of fluctuating stress. for example tension.compression.bending or shear: occurnng during anappropriatestresscyclein thecomponentdetailhavingregard to the loading that It Will experience

r ; extreme values of stress occurnng I nJM ax MIOthe stress cycle

=consideredas negative ifit S ofoppositesense to t

= permissible fatigue stress in bending

= permissible fatigue stress in shear

= fatigue reference stress at which acomponent detail has a 90 percentprobability of survival

r . M =extreme values of axial tensile stress, a M ax I infnM a x J b MIO= extreme values of stress in bending

. . =extreme valuesoftorsional shearstressf1MI,l e Mut

fM IO = maximumdegreeofstress Iluctuauon.fM..

7.4.5.5 Permissible fatigue stress

The permissible fatigue stress P : for each type ofstress. for example tension, bending or shear is givenby

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Pt 0.8 Ptfor hoistilll methanisms 0.85 tfor all other mechanisms

Where the component detail is subjected to a singletype of fluctuating stress that is 1 shall notexceed P the permissible fatigue stress.

The stress combination occurringmost frequently inpracticein a componentdetail is that ofbending andtorsion Thedetails subjected to this combination shallbe designed so that:

f ~ : -2+ ~ Y1.07.4.6 Checking or Crippling

Componentsubjeaed to crippling that is overall flexuralbuckling due to axial compression shall be checkedso that the calculated stress does not exceeda limitstress determined as a function of critical stress

above whichthere is a risk ofcripplingoccurring. Forthis checkco-eflicient e as givenin Table2 shall betaken into account.

7.4.7 Checking fo r Wear

In the case of parts subjected to wear, the specificphysical quantities such as surface pressure or theciraunferential velocity mustbe detennined. Thefiguresmust be such that on the basis of present experiencetheywill not lead to excessive wear

7.4.8 Means 01 ccess

7.4.8.1 General requirements

In front of the panel the working place shall be minimumof500mmor widthof the doorofthepanel or whicheveris more. Safemeans ofaccess shall be providedto the driver s cabin and to every place where anyperson engagedon the inspection repairand lubricationof the crane will be called upon to work; adequatehandholds and footholds being provided wherenecessary.

7.4.8.2 l a ~ o r ~ s

Every platform shall be securelyfencedwith doubletiered guard railshavinga minimum height 1 1 m andtoe boaids unless parts ofthecrane structure providedsafely The platfonn nonnal widthwith onlycbcck platesshall be of sufficient to enable normal maintenancework to be canied out safely On bridge platform whichsha1Ibe not less than0.75min nonnal width, the fencingshall extend along the full length of the outeredge.

Guard railson the crabsideofthebridgeplatform maybe provided, if required.

9

IS 3177 : 1999

7.4.8.3 Ladders

Side of ladders normal width with onlycheckplatespreferablyfromplatform to the cabin shall extendtoareasonable distance above the platforms or otherreliablebandholds shall be provided. Ladders shall possible, slope forward Vertical ladders exceeding3 m in lengthshall be provided with back safetyguards

8 SELECI N OF COMPONENTS

All componentsshall be selectedor designed underthe loading conditionsspecifiedin 7.3.

8.1 Liftbtg ook

8.1.1 General

Lifting hooksshall comply with IS 381 S and IS 5749.

8.1.1 Types

For loads up to and including t, Shank type plainhooks be used unless otherwise specified by thepurchaser. For loads of t and over, hooks ofRamshom type or triangular lifting eyes are to bepreferred

Where there isa chanceof foulingof hook hook withhooklatch is to be providedwith closing fingers topreventslippageof loadand the risk ofdisplacementofloadduringhoisting andfor lowering operation Ctype hook shall be used However an option can begiven to the purchaser on whether hook is to beprovided with closing fingers or hook latch. In thiscase the hingelugforthe closing fingershall be forgedwith the hook The finger shall be capableof takingload equal to 1.5 times of the weight of hookblockwithout distortion in accordance with IS 13870 Part 1 .

8.1.3 Mounting

Swiveling hooks shall be mounted on thrust bearings.A protective skirt shall be provided to enclose thebearings.The thrust bearings shall be providedwithfacilitiesfOrlubrication howeverfacilities for lubricatingneed not necessary in case of self lubricated ny on

bearing pads. If required a locking device shall befittedto prevent rotation of hook

8.2 Sbaft.

8.2.1 Material

All shafts shall be made ofsteel. Shafts and axlesshall have ample strength, rigidity and adequatebearingsurfaces.Suitablesurfacefinish for stressedportionsof the shaftsshall be selectedhavingregardto size,stresslevels, severity ofstress raisingfeatures

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IS 3177 : 1999

and the needs of bearings, seals, etc. Adequateallowances shall be madefor the effective losses insection due to key waYs splines, etc. Large changesin the section shall be avoided wherever pOSSible.Shafts,i shouldered,shall be provided with fillets ofas largea radiusas possible and/or be suitably tapered Allshaftsshall be supportedon minimum two bearings. Splinesand serrations shall comply with relevant IndianStandards.

The travel driving shaft or shafts shall be supportedon self aligning bearings at a distance so tbat thedeflectiondue to theselfweight ofthe shaft isbetween

0 03 to 0.05 percent of unsupported length of theshaft. Angular deflection of the line shaft at torquecorresponding to 1. S times the motor torque duringacceleration period shall not be more than 0.25 permetre of shaft length. The drive for the line shaftshall be mounted as close as practicable to the centreof the span. Each part of the drive shaft shall bedesignedto transmit maximumtorquedueto the mostunfavourable load position.

8.3 Wire Rope

8 3 1 General

Hoisting rope, unless otherwise specified or agreedby thepurchaser, shall conform to IS 2266.Steelcoreropes with constructionand tensiledesignationofwiresas 1960 shall be used fortheapplicationsunderwateror in the corrosive atmosphere or while handling hot

metal. Ropes working under water and in corrosiveatmosphere should be galvanized.

8 3 2 Selection Procedure

The selection procedure adopted here assumes thatthe ropes are lubricated correctly, that the windingdiameters on the pulleys and drum are selected incorrespondencewith this standard and that the ropesare properly maintained, inspected and periodicallyreplaced. Theselectionof ropediametershall be relatedto the following:

a group classification of the mechanism,

b) the rope receiving system employed and itsefficiency,

c) rope inclination at the upper extreme positionof thehook, if the rope inclination with respectto hoist axis exceeds 22 5

The minimum breaking load Fo of the rope intendedfor a particular duty shall be determined from theformula given below, however impact factor shouldnot be considered while calculating the rope tension.

10

where

S II maximum rope tension considerinSinclination of the rope in the uppenDOIlpcsiticn.

Zp minimumpractical co efBcieDt~ l d j l t z t i nFor normal oonditionZ sha be taken equalto 6.0.

Cd = duty factorfor oistiq as defined in 7.4.3.

8 3 3 Examination Maintenance n Discard ire opes

For the examination, maintenance and discardcriteria of wire ropes, guidelines given in IS 3973shall be adopted.

8.4 Rope Dna

8 4 1General

Drumsshallbe designedfor single layer of ropes onlyand shall be designed with multilayer guided ropewhen agreed to between the manufacturer and thepurchaser.

8 4 1 Length of theDrum

The drum shan be of such length that each lead ofwire rope has aminimwn of twofullturns OIl thedmmwhen hook is at its lowest position not taking into

consideration the turns covered by the wire ropeanchorage and one spare groovefor each leadof thewire rope on the drum when hook is at its highestposition.

In the casewhere the drum flangts are not provided,a free length not less than 4 times to the diameter ofthe wireropeor 100 mm dia whichever is more is tobe providedbeyondthe last groovecenter line at theanchorage point.

8 4 3 Flanges

The drums shall be flanged at one or both ends inthe following conditions such as:

a For singleflange drum at theend wbere wirerope is released.

b) For run s having bandedgrooves at bothendsif wire ropes are released from the eDd ofdrums.

c) For multi-layer wire ropes at bothends.

d) If required by the purchaser.

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where

= 12 x d C x (d df H;

The diameter of the drum measured at the bottom ofthe grooveshall be not less than the value calculatedas follows:

Dd = diameterof thedrum measuredat the bottomof the groove in mrn:

d = calculated diameter of the rope, in mrn;

Cdr = duty factor for hoisting for the appropriatemechanism class as defined in 7.4.3: and

= factordependent on theconstructionof wirerope.

For wire rope construction:

I == 12)( d x C df) ~ r c:

== 8 d Cdf C rc for equalizing sheave.where

D diameter of the sheave measured at theI

bottom of the groove in mm,

d ::::diameter of the rope,

Cdr = duty factor for the appropriate mechanismclass as defined in 7.4.3, for hoisting,

C = factor dependent on the construction of there

8 5 1 Grooving

Sheave shall have machined groove. The contour atthe bottom of the groove shall be circular over aminimum angle of 120 and shall have an includedangle of 50. The grooves shall be finished smoothand shall be free from surfacedefects likely to injurethe wire rope. The depth of the groove shall not beless than 1.5 times the diameter of the rope The radiusof the grooveshall be between 0 53 to 0 59 times the

diameter of the wire rope rounded of upwards to thenearest 0.5 nun.

8 5 2 Diameter o f the Sheave

The diameter of the sheave measured at the bottomof the grooveshall not be less than that at the drumsspecified in 7.4.6. The diameter of the bottom of thegrooveat an equalizing sheave shall not be less than62 percentat the minimumsheave diameter. ThevalueIS calculated as follows:

8 4 9 Rope Anchorage

The end ofthe wireropeshall be anchoredto the drumin sucha waythat the anchorage is readilyaccessible.Each wire ropeshall have not lessthan two full turnson the drums whenthe hook is at the lowestpositionnot taking into considerationthe turns covered by thewire rope anchorage.

8 ~Sheaves

8 4 7 Material fo r the Drllm

Drumsshall be made of seamless pipe as per ASTMA 106ORA and B.cast ironof minimum Grade 2Scast steel, rolled steel of welded construction and incase of welded drum this should be stress relieved.

8 4 8 Strength o f the Drum rums shall be designedto withstand the compressivestresscaused by thewound of wire rope,bendingstressdue to beam action andtorsional stress.

< 10 ,C re = 1.12,C = 1.25.rc

6 x 36 or6 x 376 x 246 x 19

Where provided, th e flanges sball project above th ewire rope to a distance not less than 2 times of thewire rope diameter

8 4 4 ead ngle

The lead angle ofthe rope shall notexceedS o either

sideof helix angle of the groove in the drum.1.4.S Grooving o f t ~Drum

Rope drums shall have machined grooves and thecontour at the bottom of the grooves shall be circularover a minimum angle of 120 0 .

Grooving shall be finished smooth and shall be freefrom surfacedefectslikely to injurethe wire rope Theedges tw n the grooves shall be rounded. Theradius of the groove shall be between 0.53 to 0.59times the diameter of the wire rope rounded offupwards to the nearest 0.5 nun _The depth oCtOO grooveshall not be lessthan u ~ umes thediameterof thewireropes for drum wuh single layer of the wire rope and0.2 times th drametcrofthe wire ropefor multiple layersof wire ropeon the donn. The pitch of the grooves ofthe drum shall not be less than 1.08 times thediameterof the wire rope for the drum with single layer of thewirerope and 1.05 tunes the diameter of the wire ropefor multiple layers of the wire rope on the drum,

8 4 6 Diameter o f the Drum

The diameter of the drums at the bottom of the grooveshall be standardized to sizes 200 250 315 400 500630 710 800 900 I 000 and 12501nrn.

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conical) treads. With flanges or with the help ofhorizontal guide rollers they shill guide the crab orthe crane effectively to prevent derailment. Thewheels shall be mounted in such a manner as tofacilitate removal and replacement.This clausegivescriteriafordeteiminingthesizeof the wheelsrequiredto meeta particular duty. It is assumed here that therail track is maintained in good condition and thatthe wheelsare correctlyaligned.

8.6.1 Design Factors

The factors those need to be considered whendetermining the required. material and diameter forrail wheelsare as follows when:

a) loadon the wheel,

b) typeand the materialof the rail,

c) speedofrotation of the wheel (n)d) lengthof travel L on the rail and numberof

loadcarryingwheels Z) operatingonthesamelengthof rail, and

e) groupclassificationof the mechanism.

8.6.3 Wheel Hardness

The minimum hardness of the wheel rim should bemaintained 300 to 350 BHN with minimum depthof 10 mm. The formula for determination of wheelhardness is as follows :

1.3 BHr C LBHw = : ~ -Cz ) d

~

1.25 12

6 to 95

Table5 Values of Coefficient err

CIT

The angle between the wire rope and a plainperpendicular to the axis of the pulley shall notexceed 5. where

8.5.3 LeadAngle

ropeas defined in 8.4.6, and

rr= co-efficient depending upon the type ofreceivingsystem.

For sheaves thevalue of the co-efticient Crrdependsupon the number of pulleys in the reeving and thenumberof reverse bends.

Takingthe valuesof

Nb = I fora drum,Nb = 2 fora pulley carrying the rope in the same

direction of wrap no reverse bend),Nb = 3 fora pulleycarryingthe rope inthe reverse

directionof wrap reversebend),Nb = 0 for compensatingpulley,and

N,= isthe sumof thesevaluesof Nb for thegivenropereeving.

The correspondi ng valuesof the co-efficient rr aregivenin Table 5

8.5.4 Material

Sheaves shall be manufactured from cast steel, orforged steel or rolled steel or from suitablegradesofnylon

8.5.5 Sheave Guards

Sheaves shall beprovidedwith rigid guards to retainthewire ropes in the grooves The guardsshallfitcloseto the flange having a clearance not morethan onefourthof the diameter of the wire rope between thesheave and the inside of the guard. Bottom blocksheaves shall be enclosed except for wire ropeopenings.

8.6 Track Wheels

8.6.1 General

Track wheels shall have cylindrical or tapered

BHw =Brinnelhardnessofthe wheelrim;

BH = Brinnel hardnessof the rail;r

CL = factordependent on the rail length L usedby Z number of wheels For values refer able 6;

Cz = factor dependent on the number of load

carrying wheels Z Forvalues referTable7; and see Fig. 4 and 5)

d = factor dependent on the wheeldiameter DForvalues referTable 8

8.6.4 Material

The material for the track wheels should be ofC S MN 7S andalsocanbeofsteelor castor wroughtor shall have steeltyre shrunkon and registeredwithminimumhardnessas obtainedearlier. The steelshallnotcontain more than 0.06 percent either of sulphur

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or phosphorus. For light dutycranes. cast iron wheelsshould be prohibited.

Table 8 Valuesof Co-effcient Clause 8.6.3

D= _ 5 Wa

or

W x CdC x C ICD

1.5 a C Cbh sp

Diameter C,mm

160 1.00

2 1.03

25 1.06

315 1.09

4 1.12

500 1.15

63 1 18

71 1.21

800 1.21

9 1.24

1 1.24

1 250 1.27

where

D= tread diameter of the wheel in mrn;

W 2 maximumwheel load in newtons;

a = useful width of rail

Cdr= duty factor for the appropriate mechanismclass as defined in 7 4 3 ~

Cbh = hardness factor for the wheel material. Forvalues refer Table 9. Here wheel hardness

Bhw = as calculated in 7.4.3 shall be used even if

wheel rim if hardenedmorefor longerwheellife;

Car = safety factor depending on the material usedas defined in 1 4 3 ~and

IP ~ co-efficient depending on the speed ofrotation of the wheelas defined in Table 10.

Fora mil with a totalwidth 4 B having roundedcomersof radius r at each side and having:

a = B r Flat bearing

Table 6 Values of Co-efficient C I. Clause 8.6.3

Table 7 Values of Co-efficient C z. lause 8.6.3

The tread diameter of wheels shall be standardized tosizes 160 200,250, 315,400, 500,630, 710, 800, 900,1000 and 1 250 mm. The use of wheels of diametergreater than 1250 mm is not recommended. Theminimum tread diameter of the wheel may becalculated from either of the formulae given below:

8.6.6 Diameter o f Wheels

In assessing the individual loadings arising under

Case 1and Case II loading conditions, the hook loadimpact factor is not applied.

8.6.S Loading onditions

Z in NOI e,m

2 1.00

4 1.08

6 1 13

8 1 17

10 1 20

12 1 22

14 1

16 1.26

Lenath C r,m

10 1

16 1.05

20 1 1 , 11

31 5 1.14

40 1.17

S 1.20

63 1.23

80 1 2 6

100 1.29

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IS JI77:

20 0 30000000

l Lo

l.

V

Vo

10

1. 2

1.1

1.3

N

o

1. 5

1 .4

Diameter mm)

FIG. 4 SIZE FACTOR, C

DIAMETER rnrn

FINE TURNED R t=6 .51Lm)

FINE GROUND Rt =2 51 Lm

LAPPED/ROUGH

POllSHEO Rt =2 .5 IJ-m

TURNED/ROUGH R = 2 l.Lm

ROUGH TURNED Rl =30 IJ.m

1100OOO000060 000

0 .+ .= : : : : J -=== : : :L . -== : : : : : : : : : : . . . J . . . .L._ l ..J400

J .2

1. 1

1.4

1. 3

1. 5

1 -1

U

FIG. 5 SIZE FACTOR, C.

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Table 9 Co-efficient C bh Clause 8.6.6)

Table 10 Values o r ~ m i e n tC. p Clause 8.6.6)

w here

b Convex bearing surface a = IJ - 41

r

where

f Ml tx maximum wheel load, an d

P minimum wheel load. ~ It,

H.6.9 Flanges

The dimension o f flanges fo r guiding track wheelsHl th e base shall not be less than the values givenin Table 11.

Table 11 Minimum Flange Dimensions louse 8 6 9

\ dimcusrons In millimetres

Diameter of Depth of I a n ~ ~ Thickness o fWhf f ls F lange

160. 200. 250. 16 16

31S. 400. 50 0 20 20 I

610. 710, ROO 25 25< 00. I 00 0

I 250 ] ].-

Rota t iona l Speed C aprpm

20 0 0.66160 0.72

12 5 0.77

11 2 0.79

10 0 0.82

90 0.84

80 0.87

71 8 ~

63 0.91

56 0.92

50 0.94

45 0.96

40 0.97

35.5 0.99

31.5 1.00

28.0 1.02

25.0 1.03

22.4 1.04

20.0 1.06

18.0 1.07

16.0 1.09

14.0 1.10

12.5 I 1

11.2 1 .12

10.0 1 .13

8 1.14

6. 3 I . 15

5 6 I 16

5 0 1.17

3

PMtiX + P MIJlP m c a n

H.6.H De ernll l1u U)n of the Mean Wheel Loading

For loading conditions o f normal service without windand nonnal service with wind a mean wheel load shallbe dctcmuncd from the relationship by the formula givenbelow.

B = width of th e rail . an d

r :: radius of th e rounded corners of th c side.

8 6 7 D ct cr nu n atton the AJax/mum S ta ti c W he elLoading P,

Where this Sh;IJl be th e maximum whee l l oad occurringw it h t he wheel s ta ti c u po n t he rail In any of th e fourcases o f loading.

8 .. . r,

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8 .6 .1 0 T he flanges shall be adequately tapered toprevent it f rom rubbing o n t he rails. Fillets of radius0.7 to 0. 9 r shall be provided where r is th e radius ofrail comers

8 6 Width Tread

The width of th e wheel tread shall be greater than therail head by an amount which shal l suitably allow forthe variations in the gantry rail alignment, gantry trackspan dimensions and crane span dimensions.

8.6.12 Adhesion the Drive Wheels

To eliminate slipping of th e d ri ve wh ee ls of th etravelling mechanism of the crane or crab, the designshall be checked for adhesion under the most unfavourable combination of loads producing maximum an dminimum loads on the drive wheels. Th e co-efficientof adhesion fr ict ion) shal l be taken as 15 for dry

rails an d 0 1 for damp rails.8.7 Bearings

8 7 General

Bearing pedestals an d mounting shall be capable oft ra ns mi tt in g t he load from the b earin g to th esupporting structure. Suitable provision shall be madefor those cases where the resul tant load is not actingas a compression load on a bed plate. Suitableanti-fr ict ion bearings shal l be used for live or fixedaxles for wheels, for the shaft s used for sheaves an ddrums an d for the shaft s suppor t ing gears.

Suitable steel bushing as used in bogies an d steel bushbearings made out or phosphor bronze, cast iron ornylon ca n be used for hinges or balances of cranebridge or trolley, cross beams for hooks , magnetsuspension, links for grab bucket an d at places whererotation is not powered.

8 7 2 Anti Fr ic tion Bearings

Anti-friction bearings shall be installed an d fitted inaccordance with the manufacturer s procedures withadequate provision for lubrication.

Arrangements for axial location shall be in accordancewith cor rect prac tice so that unforeseen additionalbearing loads ar c not introduced. Bearings shall becapable of withstanding the greatest static an d ordynamic load it ca n be subjected to under whicheverof the loading cases is the most unfavourable. Th ebearings shall have minimum static load capacity f:for a particular duty as given below:

. where

P = m ximum static load on the bearing nder y load condition an d for the equivalentload to be determined as spec if ied byth e manufacturer.

Cd = duty factor as defined in 7.4.3. Life ofth e anti-friction bearings shall be calculatedin ac co rd an ce w ith the m an ufa ctu rer srecommendations an d based on workinghours speci fied for- th e duty of themechanism.

8 7 3 Pla in Bearings

Th e selection, fitting, lubrication, th e pressure andrubbing velocity shall be in accordance with therecommended practice an d service experience for thematerial involved having regard to the nature of the

loads an d operating conditions. Plain bearings shall,where practicable, be of th e adjustable ca p type. IfPhosphour Bronze bearings are used the pressure shallnot exceed 6.86 MPa, wherein MPa is th e unit ofpressure.

8 7 4 Lubrication

Provision shall be made for th e service lubrication ofal l th e bearings unless scaled an d lubricated for life.Ball an d roller bearings shall, in addition, be suitablylubricated before assembly.

S.8Gearing

8 8 1 General

All gears shall be machine cut hardened an d profileground and shall confirm to relevant Indian Standards.However the Crane gearings can be designed or selectedon the basis of the condit ions g iven below:

a service exper ience under condi tions corresponding to th e classification parametersinvolved, or

b other recognized standards or codes whichhave been proved satisfactory in crane service,or

c any other method for making calculationswhere manufac ture r mus t ind icate or ig in ofthe method adopted if asked by th e purchaser.

T he g ear in g shall be designed for a service lifecompatible with the service life of the mechanism, theclass of utilization an d state of loading used for th emechanism, and having regard to the prime moveran d brake.

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8 8 2 Material

All gears shall be of cast or wrought steel of forgedfrom low/medium carbon alloy steel an d suitably heattreated.

8 8 3 Gear BoxesAll pair of gear boxes shall be so except for planetarygear boxes either spur or helical and gears shall beautomatically oil lubricated designed that the first pairof g ea rs s ha ll a lw ay s be helical an d gears sha ll beautomatically oil lubricated. Th e gears shall be readilyremovable an d th e boxes shall be oil t ight . They shallbe of rigid construction an d fitted with inspectioncoversand lifting lugs where necess ry The inspection covers shall be so positioned that th e first an d secondp in io n s ha ft s can be inspected. M in im um a ndmaximum oil level indicators and facilities for oi l

filling, oil drainageand

ai r breathing shallbe

provided.All gear boxes shall- be in totally enclosedconstruction. Teeth shall be machine cut suitablyhardened and tempered an d shall conform to AGMAor IS 4460 Th e surface hardness of pinion sha ll bebetween 266 to 30 0 BH N an d that for gear shal l beb et we en 2 17 to 25 5 BHN. Difference of hardnessof pin ion and gear m us t n ot be less than 20 BHN.

Th e gearbox mounting shall be machine cut, hardenedan d profile g ro und t o relevant Indian Standards andshall be seated an d positively located on machinedsurface.

Material of the gear box shall be cast, wrought or forgedfrom low/medium carbon alloy steel an d suitably heattreated. Th e fabricated gear boxes shall be stressrelieved before machining. Th e internal surfaces of thegearbox shall be painted with oil resisting paint.

8. 9 Couplings

All couplings shall be cast, wrought or from forgedsteel, tooth portion to be hea t t reated to hardnessHB 241 280 an d a lso shal l be designed to suit th emaximum torque that may be developed. Solid andflexible coupl ings shal l be a li gn ed w it h th e sameaccuracy so that they match accurately.

Hoist drums shall be connected to g ea r b ox o ut pu tshaft by means-of flexible drum couplings or barrelcouplings to cater for misalignment, frame distortions,etc, an d also to facilitate removal of hoist drum. Shaftcouplings shall be as near as practicable to the bearings.

8.10 Fasteners

8 1 1 Keys

Keys an d key-ways shal l conform to relevant Indian

IS 3177 : 1999

Standards. Keys shall be so fitted an d secured thatthey can notworkloosein service.

8 1 2 Bolts Nuts Screws and Washers

AI bolts, screws an d set screws in rotating parts shallbe locked. All other bolts an d screws shall be fittedand locked i f required by the purchaser so that theydo not get loose. Bolts in tens ion shal l be avoidedwherever possible. All bolts screws nuts shall bemade ou t of high tensile alloy steel material an d shallbe in accordance with relevant Indian Standards. Blackbolts shall not be used. All bolts an d nuts sha ll beeasily accessible.

Tapered washers an d t ap er ed p ad s w he n u se d shallbe tack welded in place. All washers shal l conform toIS 1364 an d IS 1367 respectively.

8.11 Buffers

8 11 1 General

Suitable buffers shall be fitted to each end of t he e ndcarriage assemblies a nd o n both sides of crab or thebridge.

Buffers shall be so mounted to permit easy rernov alof wheels. Limit switches shall be provided in such away that drive motors are switched otfbefore the buffersar e pressed. Buffers will be provided between th ecranes if more than on e crane is running on the sametrack

8 11 2 Type Buffers

Spring buffers, hydraulic buffers an d buffers madeou t of resilient plastic rubber or polyurethane maybe used. Wooden buffers shall not be used. Buffersshall have sufficient energy absorbing capacity tobring the loaded crane or crab to rest from a speed50 percent of th e rated speed at a deceleration ratenot exceeding 5 m/s

8.12 Braking

8 12 1 General

a The parts used for braking shall be madefrom hard wearing material with adequatethe rmal capac ity for the du ty requi red. Dueallowance shall be kept for th e brake drumcapacity to d is si pa te h ea t g en er at ed d ue tof requent braking. Th e rubbing surface shallbe smooth an d free from defects. Th e brakelining shall be protected, from water, grease,oil or other adverse effects.

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b The bearing pressure on the linings shall beconducive to uniform braking an d long life.Brakes shall be provided with means o fadjustment to compensate for wear.

c All electro-mechanical or electro-hydraulic

brakes shall be applied automatically bysprings or weights when the power supply tothe brake is interrupted or when the circuitbreaker is opened or when th e controller isbrought to of f position. Power applied brakesshall not be fitted without a back up systemof power released type an d w it ho ut p ri orapproval of the purchaser.

d Springs of electro-mechanical brakes shallbe of th e compression type an d shall not bestressed in excess of 80 percent of th e elasticlimit of the material. Brake weights ifprovidedshall be securely bolted to th e levers andlocked.

c Under service condi tions brakes app lied byhand shall not require a force greater than 120N 12 kgf at the handle. Brakes applied byfoot shall no t require a force of more than200 N 20 kgf on the pedal. Th e stroke ofhand levers shall not exceed 300 mm an d ofpedals 150 mm. Locking devices shall beprovided on brake levers where necessary.Brake pedals shall have non s lip surface.

1 Electro-hydraulic thruster operated brakesare permissible on all motions.

g Appropriate mechanical, electro-hydraulicbrake magnet or any other alternative brakereleasing gear ma y be used.

8 2 2 Braking Path

Th e braking path of the crane motions shall be withinthe distance as calculated from th e following formulaw ith a ll th e brakes applied simultaneously unlessrequired otherwise by th e purchaser:

s

where

S braking path in metres, speed of motion in metres/minute

Cdf = co-efficient for group classification an dtype of mati on as defined in 7.4.3, an d

C b 80 for hoisting motions,20 for travel motions.

8 2 3 H oi st M ot io n B ra ke

All electrically operated hoisting motion shall be fittedwith an electro-bydraulic/electro-magnetic fail safebrake. Th e brake will arrest the motion an d hold atrest a ny l oa d up to an d including overload test load

at any position of the.lift.Th e provision shall be made to enable ny laad capableof over coming th e friction in th e system up to an dinc lud ing the test load to be lowered safely in acontrolled manner in the event of power failure. Th ebrake shal l be designed to exert a restraining torqueof minimum 50 percent greater t ha n t he maximumtorque transmitted to the brake from th e suspendedload under th e load ing co ndition s as specifiedin 7.3, In estimating this torque th e effects of frictionin the transmission system between th e load a nd t hebrake shall be ig.nored.

Cranes handl ing dangerous liquids be fitted with anindependent delayed action type additional brake onth e hoisting motion. Each of these tw o brakes shallhave minimum braking torque of S percent of th ecomputed full load torque.

Total torque of the external ly applied brakes actingsimultaneously shall no t be more than the to ta l pullou t torque of th e motors,

8 2 4 Travelling Molion

Every electrically operated t ravell ing motion shallbe fit ted with a mechanical or hydraulic brake or anautomatic electro-magnetic I electro-hydraulic brakeor a combinationof the two, if required, Th e brake shallbe capable ofbringing a fully l\laded crane to rest withleast possible shock from the highest speed it can attainwith electro-magnetic/electro-hydraulic brakes, limitswitches shall be provided in this motion.

Th e travelling motion of every electric outdoor craneshall be provided with the automatic electromagnetic lelectro-hydraulic parking brakes i f th eservice brake is no t of eletro-mechanical type. Alloverhead cranes working outdoors shal l be providedwith an additional storm brake for anchoring it whenit is left unattended or under th e storm fondition.Gantry cranes working outdoors with rails on groundshall be provided with rail clamps or s r ws jack orchain anchor at each corner for anchoring it duringthe storm.

The braking torque shall not be less than the full loadtorque transmitted to th e brake an d shall no t be moret ha n t he pullout torque of th e motor.

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8.12.S raversing otion

The cross traverse motion should also necessari lybe provided with brake/brakes as specified for longtravel motion. When electro-mechanical brakes areprovided, en d limit switches shall be provided in thismotion

The cross traverse motion brakets) shall be capableof bringing the fully loaded crab to rest with leastpossible shock from highest speed it ca n attain.

Th e braking torque shall no t be less than th e full loadtorque transmitted to th e brake an d shall not be morethan the pul lout to rque of th e motor.

9 GU RDING N D WE TIlERPROTE IlON

9.1 Guards

All gears, wheels, pinions an d chain drives shall be

totally encased by th e g ua rd or by th e structure ofthe crane so as to be safe.as i f complete encasementis provided. Effective guards shall be provided for allrevolving shafts an d couplings rotating at high speedsor having protruding parts or arc so situated in relationto th e structure of th e crane as to be safe as if guardswere provided. The sheaves of th e h oo k b lo ck s ha llbe guarded to p re ve nt t he possibility of trappingbetween a sheave and the in-running wire rope.

Suitable guards shall be provided on th e down-shoplead side to prevent accidental contact between wireropes or hook block or I if t ing attachments an d live

conductors. It is also suggested that al l guards an dprotective e qu i pm e nt s ha ll be painted in GoldenYellow' or as in confirmation to rclcvcnt IndianStandards. This is required to ident ify abou t th elocation o f th e g ua rd s a n d protect ive equipment inth e crane easily for th e replacement of t he g ua rd s/protective equ ipment while commiss ion ing or whileth e crane is taken up fo r maintenance work.

9.2 Weather Protection

Fo r outdoor crane al l e le ct ri ca l a nd m ec ha ni ca lequipments shall be adequately protected from th eweather. All weatherproof c ov er s s ha ll be easilyremovable.

, 9.3 Painting

Before dispatch o f th e crane. th e complete cranecovering structural, mechanical an d electrical parts shallbe thoroughly cleaned of l dirt, grease, scale an d rustby s ho t b la st in g or chemica l c lean ing methods. Asi ng le co at of primer shall be given to al l partsexposed to the weathering effects an d if ar c not already

IS 3177 : 19 )9

treated earlier or effectively lubricated. At least twoadditional finishing coats of paint Cor indoor cranesoutdoor cranes of colour of customer's cho ice shal lbe g iv en o n all primer painted surfaces.

All moving parts up to t he h ei gh t, of 5. 0 m fromworking level or ground s ha ll b e painted inGolden

Yellow colour. Th e bright exposed parts of the crane'shall be given on e coat of rust inhibitor. Interior of gear boxes shall be p ai nt ed w it h on e coat of ( ilresisting paint. Areas that are inaccess ib le a f te rassembly or erection shall be treated before assembiyor erection.

Where t he c ra ne s a rc s up pl ie d fo r l s in abnormalw or ki ng c on di ti on s special protection ma y benecessary.

Any a dd it io na l r eq ui re m en ts r eg a rd in g paintir gshall be as agreed between th e purchaser an d tt e

manufacturer.10 LUBRICATION

Provis ion shall be made for lubr ica t ing a l l bear ingsunless sea led or lubricated for life, m at ti n g g ea rsand chain and sprockets arrangements. Wherenecessary easy access shall be provided.

In case central ized lubricat ion system is asked by th epurchaser, provision shall be made at th e bearingsto ven t the lubrican t pressure.

Lubricating nipples, pipes, an d adopters shall generally

comply w it h t he re levant Indian Standards.

A lubricating chart shall be provided indicating al lthe lubr ica ting points with Red colour' pain t th etype of lubricant a nd r ec om me nd ed frequency oflubrication.

11 MOTION LIMITING DEVICES.

11.1 o i t i n ~Limiting Devices

Positively operated hoist ing motion limiting devicesshall be provided that stops the upward an d downwardmotion whCn predetermined level is reached to prevent

over winding or over unwindingNOTE - Th e limiting device shall be regarded as a safetyfeature an d not as a routine operational means of stoppingWhere normal operation of ~ crane necessi ta tes frequentapproach to th e upward hmu, an addruonal motion limitingdevice shall be provided t hat ope rat e s independen tly an drequires manual resetting

11.2 Cross Traverse an d LongTravel Limiting Devices

Limiting devices shall prevent the followi ngconditions:

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a over t raveninl and over travelliDI_ and

b collusion where two or more craneltrolleysoperating on the same track.

11.3 Load IDdicadoa Load UadtiDl Devica

Load indication and limiting devices ar e recommendedif weights of objects to be lifted ar e not knownaccurately. When fitted they shall sense the loadon the crane by means other than the currentconsumed by the hoist motor the load lifted is morethan S.W.L. load limiting devices shall stop furtherhoisting operation till the load is removed or reduced.

11.4 DrawiDp an d Documeata

Following drawings-and documents shall be submittedfor approval of the purchaser before manufacturingof the crane:

a GA drawing of the crane;b GA drawing of crab/trolley;

c GA drawing of individual mechanisms;

d Drawing of bridge end girder and theirconnection;

e Sub-assembly drawing for wheels hookblocks and hoist drums;

f Calculations for selection of motor reducerbrake couplings etc; an d

g Calculation for bridge girder end carriageand their connections.

SECTION ELECTRICAL

12 MOTORS

12.1 General

The motors shall be selected to lake care of loadingconditions as given in 7.3.2 and to suit the duty ofthe mechanism in which it is used. The motors shallbe suitable for frequent reversing frequentacceleration and braking.

12.2 Selection of Motor Sizes

When the duty cycle ca a be adequately assessedd c or a.c. motors for any crane motion may beselected so that the motor temperature in actualservice shall not exceed tbe permissible limitsspecified in IS 325 for three phase induction motorsor other relevant Indian Standards s Annex Ftaking into account the class of insulation adopted

20

and the ambient temperature at th e craBe location.When datY cyc c can DOt lie aaeaecI therecomme clcd assumptioas a c design proceeclinpare set out in AJmcx C forthe selection of moton tosuit duty .cycles an d normal service conditions.

de Moton shall be series wound and ac moton sballbe squirrel cage or .sl iprinl induction type unlessspecified otherwise. The de moton should beselected in agreement with their manufacturer-s. Itis necessuy to know the torques th e power calculatedand the true operating conditions of the motor.

NOTES

I Motor power u computed in Annex C has boea multipliedby service factor to make the motor thermally pablofor the duty condition. While delianina controls. the cranemanufacturer should use computed motor-power withoutservice factor for selection of components. Thecomponents selected should be able to carry the full load

current the motor power computed wi thout servicefactor at the specified duty cycle and ambient temperatureof operation of tho crane.

1 If specially required by the purchaser the drive motorshould be protected against over heating by means ofthermiston embedded in the motor windinp. Matchingthermistor trip relay should be provided in the controlpanel.

1 3 Enclosures

All crane motors sha ll be total ly enclosed with orwithout fan cooling arrangement and shall conformto IS 3 ~ IS 1231 or IS 2223 as appropriate. Theenclosures shall suit the specified service conditionsand shall be stipulated with th e enquiry or order. Ifnot specified by the purchaser the motor enclosureshall be minimum IP 44 for indoor applications andIP for outdoor applications of ac motors an dIP 23 for de motors. For outdoor applications separatecanopy shall be provided for motors.

11.4 Torque Rating

The motor shall be capable of producing maximumtorque required to produce motion in th e mostunfavourable loading condition. The pullout torqueof the motor at rated voltage and frequency shouldnot be less than 2.0 limes the rated torque forthe all mechanism classes from MIlo M8 as corresponding to computed motor power without servicefactor.

IZ.S UmitiDI Speed

Motors shall be capable of withstanding a maximumspeed of ~ times rated speed or 2 000 rev/minwhichever is less.

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12.6 ta.ladoD

The motor s b n ~ofClass 8 insulation or betteras c1aIIiftecl ia the relevant Indian Standardspecifications

12.7 Aeeealbility

Motors shall be SO located tbat the brushes, gear an dterminals are accessible for inspection andmaintenance12 8 Termlnall

M ot or l ea ds s ha ll be brought ou t from t he mot orframe to termina ls in th e t ermina l box fixed to themotor. frame and shall be marked in accordancewith IS 4728.

11.9 Sliprfngl

Slipring motors shall have continuously rated slipringsamply dimensioned to give a long trouble free life.

12.10 ac Motors may be supplied in lE e frames an dde motors in AISSE frames.

12.11 Higher frame size such as above 280 ac motorsshould have ba r wound rotor.

IJ ELECTRIC BRAKING (ELECTRO-DYNAMICBRAKING

13.1 General

Electro-mechanical braking is referred to an automaticelectric brake whose action is purely mechanical and

the braking effect is nullified electrically by a solenoid,or electro-magnet, electro-hydraulic release gear.In electric braking th e energy is either returned to th eline or dissipated itt resistors. In addit ion to thespecific requirements of this code for the brakes an dirrespective of th e supply current, electrical brakingis permissible on a l l motions of electrically operatedcranes.

When electrical braking is used, provisionshall be madeto limit the current on reversal toa safe value. Effectivemeans shall be provided for s topp ing the motion inthe event of a power failure and in the case of an

emergency.Shoot brakes shall be so connected that it will be appliedwhen t he main c ir cu it -b r eaking device is openirrespective of the position of th e controller. Ifrequiredby th e purchaser. each controlcircuit shall be electricallyinter locked with al l associated shunt breaks to preventpower being applied to th e motion when the brakesare not energized.

NOTES

I If a hoist is potentiometer controlled, an auxiliary

21

IS 3177 : 1999

pole is required Oil the main circuit-break. to open theshuDt brake and control circuitl.

2 In ea M of boist motor., either the brakes are releuodwith the eneraization of motors or the moton areener.izod.

13.1 Brake Mape

The terminals of brakemagnetsshall be protectedfrom tidental contact The connectionsand windings shallbe efrectivdy protected from mechanical dama Wherenecessary magnets shall be provided with an efficientcushioning device. Ratings of brake magnets andthrusterbrake motor shall be as given in Table 12.

NOTES

1 CDF means Cycle Duration Factor .

2 The temperature rise of th e brake electro-magnet orthruster at any of the specified duty mentioned aboveshan not exceed permissible limits for the particular classof insulat ion used with due considerat ion of switchingcurrent in rush (due to field forcing in case of de magnet).

3 Maximum duration of cycle shan not exceed 10 minin case of intermittent duty. T he b ra ke magnets sha llopera te at the currents and vol tages given in Tab le 13.

Arrangements shall be made, where necessary, to preventthe brake magnet from being energized by the back emfof the mo to r when the supply has been interrupted.

Table 11 Rating of Brake Electro-magnets andThruster Brake Motor

Type ofRat ing

Actuadn . Device Duty in Percent PermissibleCDF Switching

de Magnets 2040

7260tOO

ac Magnets 20 240

ac Magnets 60 60100

ac Thruster 60 72 0brake motor

14 CRANE CONTROLLING ARRANGEMENTS

14.1 General

The type of controls to be used shall be as agreedbetween the manufacturer and th e purchaser. Craneshaving alternative control or brake circuit facilitiesshall be provided with means to prevent operation from

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more than on e facility at anyone time.

NOTE - Main circuits ar e those which carry main moto ro r m ag ne t c ur re nt . C on tr ol c ir cu it s with b r ak e c ir cu itmechanism are those which ar e used for control equipmentfor main motor or magnet

Table 13 Brake Magnet Operating Currentsand VoltaRes lause 13 2

(kW) of th e motor.

14.1.2 Control Equipment fo r DC Motors

The selection of contactors shall be made On th ebasis of S 3 - 40 percent rating arrived after applyingappropriate service factor to the computed power of

th e motor. The rating of the control gears such asswitches overloads etc shall be selected accordingto th e computed motor power without the service factorof the motion served an d not on the motor powercomputed bythe thermal requirements.

*Th IS intended to apply with hot c orls correspondingto th e duty cycle at r a ted vo lt ages Th e temperature riseof th e brake m agne t shall not exc ee d tha t allowed forth e control equ ipmen t f i t ted

14.2.1 Control Equlpnu:nt. Or de Motors

Contactors, switches and allied electrical componentsshall be selected on t he b as is of calculated power in

14.2 Controllers

Controllers shall be rated to comply w it h t he relevantIndian Standard specifications. Cont rol l er s shal l beadequately protected to prevent acciden tal contactswith th c live parts Controllers in orr position shallopen all supply lines of th e respective motors, unlessotherwise agreed to In which case a warning noticeshall be fixed to the controllers. On or adjacent to eachcontrol device, there ha be a durable markingIdentifying the motion controlled an d th e direcuon ofmovement

rl \

Shunt

Wi n d i n g 5

Fo r serrcs

re srstorc o n t r o l

Potentio-meter

control

de a ~ n ~ t ~

Lift at 60p er ce nt r at ed

cur ren t

11 1< 1 at ISp er ce nt r at cu

cur ren t

Li n at 40p er ce nt r at ed

current

lIold at 5p er ce nt r at ed

current

Lif t at R5percent rated

volt ag e

Hold at 50p er ce nt r at ed

voltage

ac ~ n e t ~

-un at 85p e rc e nt r at ed

voltage

Uold at 50p er ce nt r at e d

voltage

The contactors selected under 14.2.1 an d 14.2 2 shallhave the s t ipu la ted contact life as ma y be spec if iedby th e user

14.3 Controllers Provided in th e Cahin

14.3.1 General

All control handles and pedals shall be placed inconvcrucm position to allow the driver ample roomfo r operation an d permit an unrestricted view of theload They shall be so disposed that the contacts an dterminal arrangements ar e readily accessible fo rInspection and rnamtcnancc purposes.

14.3.2 M ar ki ng D ir ec ti on Operation Controllers

Where prac t icable cont rol l er handles shal l move inth e direct ion of resul tant l oa d m ov em en t. Eachcontroller shall be marked in a p e rm a ne n t m a nn e r

to show th e motion c on tr ol le d a nd direct ion ofmovement. For ver tical lever handle operating hoistcontrollers, movement towards operator shall indicatehoisting and m ov em en t a wa y from operator shallIndicate lowering.

4 3 3 Notchmg

Th c notching fo r th e cont ro ll e r handle in th e of fposi t ion shal l be more posi tive than the notching inother positions. The handle may be prov ided wi th alock latch dead man or spring return feature Ifspecifically requested by th e customer. The control

lever shall be provided with stops and/or catches toensure safety and facility of operation. A controllerdrum fitted With a star wheel shall be regarded ascomplying WIth th e requirement.

14.3.4 Ma s ter Control ler

Master controller operated cranes shall bc prov idedwith automatic control of acceleration. Acceleratingtorque/current peak shall be limited during controllerhandle movement from on e notch to th e other withdue consideration to th e pullout torque of th e motor

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Radio crane control transmitter lever arrangement areof three motions, namely. are given below:

Holst ridge Trolley

X X Down W Z Up

23

Th e sending of a continuous or continuously repeatingsecure signal when transmit ter is in use, which thecrane receiver ca n identify. A secure signal includes

at least three characteristics separately recognizableby the receiver.

An emergency stop device shall be used for emergencystop.

A carrying harness belt shoulder strap or lanyardon the transmitter.

c) An i ntermediate relay panel on the bridge toamplify the signals for the crane contactors.

14.5.2 Radiocontrols should be designed so tha t )fth e control signal for any crane motion becomesineffective, that crane motion will stop, and conversely

signals received from a ny s ou rc e other than th etransmitter will not result in operation of any motionof th e crane. The crane must not take of f on its ownor re spond to or ge ne ra te false commands In caseelectricity failure occurs the crane must stop.

A key switch or equivalent security device on thetransmitter that ca n be used to prevent unauthoriseduse of the transmitter.

Down

oUp

44ux lloist

Down

oUp

Main Hoistrolley

y

oz

Bridge

X

oW

14 5 3 Th e arrangement of th e operating levers on theradio t ransmit ter should conform to Fig 2A Th emanufacturers should supply motion switches withdifferent shaped knobs so th at t he motion can beselected by feel an d the operator s vision remain onth e load. Modular construction shall be preferablefor easy replacement.

14.5.4 Typica l frequenc ies used for radio control sare inbetween 450-470 MH for which licence is required.The recommended cr ane controls for opera-ting are of maximum 250 metre range.

Radio crane control transmitter lever arrangement areof four motions, namely, ar e given below:

a) A portable transmitter,

b) An antenna and receiver on the bridge, an d

an d number-ofrotor accelerating contactors shall beselected accordingly. For master control ope-atedcranes the control voltage preferably 110 ac an d shallnot exceed 4 V for ac or de supply.

14.4 P e a du t Controllen

4 4 Genera l

Cranes with pendant controls shall not have long travelspeed in excess of 40 mlmin Pendant control mayeitherdescend from the crab or from the independenUy travelling trolley or from a convenient position onth e crane bridge.

4 4 2 Pendant Switches

Th e pendant switches shall be capable of withstandingrough handling without being damaged an d the covershall be effectively secured. If control is from the

loor th e electrical control circuit to the pendantshall be energized at not more than 110 V dc or acsupply

4 4 3 Pendant ontrol

On all p en da nt c on tr ol le d c ran es m ea ns s ha ll beprovided to prevent inadvertent operation from thefloor whi le main tenance work is being car ried outon the crane . An iso la to r f it ted on the crane bridge,which can not be operated from the floor will complywith this requirement.

4 4 4 Pendant ontrol Station

If the control is by push buttons or swi tches, theyshal l au tomatical ly return to the off posi t ionimmediately after they are released. On e lockable typepush button shal l be provided to switch of f controlpower when the craneis not in use an d i f other meansof switching of f is no t available.

4 4 5 Suspension Pendant Switch

Th e weight of th e pendant shall be supportedindependently of th e electric cables by means of chainor wire rope. If th e pendant enclosure is of metal it

shall be effectively earthed. A chain or hook does notprovide effective earth connection.

14.S Radio o ~ t r oSystem

14.5.1 Main features of radio control system consistof:

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IS I 77 : 1999

N )TES

1 Markings on t he c ra ne visible from th e floor. shallIndicate the direction o f bridge an d trolley travel corresponding to th e W. X. V an d Z designations on transmitter.

2 T he m ax im um w or ki ng range of radio control shall belimited 40 - 50 m from th e transmitter. This limitationreduces th e likelihood of an accident caused by the craneoperating beyond the operator s visibility,

3 It is recommended that a device is fitted to the craneto give w ar ni ng t ha t t he c ra ne is under non-conduct ivecontrol.

4 Incorporate a limited range feature, present by meansnot available to t he opera tor so that the crane will slopwh en t he extent of that range is reached.

5 If more than on e crane ar e provided with this type ofcontrols, only the intended c rane and its motion is operatedat one t ime. Th e t r ansmi t te r shan be constructed so thatit is capable of withstanding rough handling.

14.6 Control Circuits

If the mains supply is ac and the control circuitsare suppl ied at reduced vol tage, the supply to thesecircuits shall be from th e secondary winding of anisolating transformer or an isolating transformer an drectifier. The t ransformer f rame and on e pole of thissupply shall be earthed and the contactor and relaycoils shall be connected to this pole. An earthed screenshall be provided between the primary an d secondarywinding. Th e primary winding and unearthed pole ofsecondary winding of t he t ra ns fo rm er shall beprotected by fuse in line connection. Effective means.shall be provided to prevent mal-operat ion owing toshort circuits o r e ar th faults.

14.7 Rectifiers

On ac cranes, if dc supply is required, rect ifiersshall be provided for supplying the control circuit,brakes an d magnets. These rectifier units shall be ofadequate capacity to supply th e full de loads requiredcontinuously. They sha ll be of suitable constructionand mounting to withstand heat, dust, shock andvibration. Silicon type rectifier units shall be preferred.Adequate fuse protect ion shal l be provided for therectifiers. Rectifiers/thyristors used for magnets shallbe protected against switch surges.

14.8 Control fo r de supply

When a de supply circuit is used , motor acts as agenerator in th e lowering direction, the control shallbe such that:

a) motor shall not exceed a predeterminedmaximum revolutions per minute,

b) progressive degrees of braking is provided,

c) adequate light hook lowering speed is provided,

d) t he b ra ke is prevented from being releasedby back e m f o f th e m otor w he n power supplyis interrupted, an d

c) the electro-mechanical brake IS automaucallyapplied when circuit breaker or coruactor ISopened.

14.9 Drakina Controls

When an electro-mechanical brake is used as anemergency or parking brake or when such anemergency or parking brake is used with hand orfoot operated travel service brakes, the brake actuatingdevice shall remain in the circuit when the main circuitbreaker is closed. Th e brake shall apply automaticallywhen the power supply fails or when the circuit breaker

is opened or on operating an emergency stop pushbutton or switch; bu t not when the control le r handleis brought to -the off position.

Th e brake shall lift of f when voltage at the coils is aminimum of 85 percent of rated voltage. Provisionshall be made for emergency application of this brakeby means of the emergency stop push button or switch.

In th e ar rangement of connections to th e hoistingmotion brake coils, means shall be provided to ensuretha t when associated drive motors are de-energized,the stored electrical energy in these motors will not

delay th e application of th e brake.14.10 Acceleration Control

Automatic control of acceleration shall be providedfor all crane motions, unless for an y motion anothercontrol system is specified. Th e hoist motion circuitsshal l enab le any load to be lowered with safety an dthe hoist motors shall remain under effective controlwith the controller in all positions. While calculatingt he n um be r of rotor contactors , peak accelerating/decelerating torques an d pull ou t torque of the motorshould be taken into account.

For creep lowering speed on hoisting mot on relativelyflat speed control shal l be provided.

14.11 Markings on th e Crane

When th e control devices a re o th er than in a fixedposition relative to t he c ra ne , the designation ofhorizontal directions marked on the control device shallbe marked on the crane so that it is clearly visible tothe driver.

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IS PROTECIlVE EQUIPMENT

IS.l Genera.

Suitably located eff icient means shall be providedto protect every part of a sys tem from excess currentan d voltage to prevent danger or damage. Enclosureshaving minimum degree of protection IP 44 shall beprovided for aUelectrical equipmentsexcept for motorsand resistors.

~ 2Electrica Protective Device

5 2 eneral

If electrically operated contactor equipment is usedfor control of all crane motions, th e protective equipmentshall be in accordance either with Scheme A, in whicheach motion has separate protection or with SchemeB. in w hi ch a n o ve rl oa d of a ny m ot io n t ri ps ofT th ecrane supply. If drum controllers or master controllersar e used fo r the control of-all motions, the protect iveequipment shall comply with Scheme B. Also it is moreoften required that in master controller operated crane,overload of an y motion should no t trip the completecrane circuit . but should t r ip the ind ividua l circuit.

In general, overload protection shall be of electromagnetic type with t ime delay. Thcnnal overload relaysin conjunc t ion wi th h igh rupturing capacity fuses ormanual reset type overload relays may be provided ifagreed by the purchaser.

Where a mot ion is ward-Leonard controlled, provisionsshall be made for

a) protection in case of motor field failure:

b protection a ga in st t he motor creeping whenth e controller is in th e off position: an d

c) tripping of th e generator field c ir cu it w it hsuppression of generator voltages instantaneously when there is an over current of 250percent in the generator-motor loop: or aftera t im e- la g w h en there is a sustained over

current of lower value.

Operation of any of the above protective devices shallautomatically apply the electro-mechanical brakes onthe relevant motion. If other systems of control or mixedsystems ar e specified, the protective equipment shallbe in accordance wi th the recommendations of th econtrol gear manufacturer. n indelible circuit diagramof the protect ive equipment shall be provided in th eelectrical equipment compartment.

IS 3177 : 1999

5 2 2 Protective evice Common al t Motions

As minimum equipments of protection, electromagnetically operated contaetors or manually operatedcircuit breakers fitted with no volt release, capable ofcutting of f the power supply to the motion drives withunder voltage protection shall be provided. Adequateprotection against short circuit shal l be provided at .each o f the isolator posi t ions. The circui t breaker ofthe main con tac to r shall be rated to carry at least thecombined full load currents o f motors fo r an y tw omotions hav ing largest powers an d auxiliary loadssuch as magnet, etc. If specified by th e purchaserthat more than tw o motions ma y be operatedsimultaneously, circuit breaker/main contactor shallbe rated to suit the requirement. In appropriate cases.high rupturing capacity fuse may be provided.

Th e c i rcui t -b reaker sha ll incorporate the rmal an de lec t ro-magnet ic over load protect ion device for

protection against sustained overload and short circuitcondition. If adequate protection against short circuitis to be provided at each isolating positions, there willbe either HRC fuses or MCCB / AC B in each isolatingposition. As HRC fuses may lead single phasing, onlyMCCB should be provided in each isolating position.Th e circuit breaker or main line contactor should notbe rated to carry magnet full load current as magnetsupply is taken before the c ircu it breaker/main linecontactor. Th e breaker shall have adequate rupturingcapacity to withstand and c lea r fault current of thesystem. If specified a suit-able control circui t may beprovided fo r this circui t -breaker to prevent it frombeing closed when the main con tactor of a particularmotion has failed to open, although th e correspondingcontroller has been brought to its zero positron

5 2 3 Scheme Protect ive Device fo r Individual

Motions

Th e provision of overload protect ion with adjustableinverse time log overload release shall be under-voltagerelease an d with overload. The minimum provision ofoverload protection shall be such that a ll supply l inesexcept on e to each monon shall be prov ided wi thadjustable Inverse time-lag overload releases. These

shall be connected as close as possible to th econtractors they control an d shall be se t to trip th ecircuit of th e motion ontrolled when carry ing 20 0percent of th e full load current of th e motor, after ati me-lag of not more than lOs.

It shall not be possible to re instate the current supplyto the contactor closing coils of a motion until the mastercontroller for that motion is returned back to th e of f position.

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5 2 4 ac Instantaneous Release Single Pole OverLoad Protective evice fo r Individual Motions

Any motor having it s power less than one-third thatof th e largest motor and served by the same commonoverload release, shall be protected by a separateoverload release. However, normally instantaneous

release of overload relays ar e not used for individualmotion an d circuit breaker is tripped by its ow noverload. In crane with c i rcui t breaker overloadprotection is provided by circuit breaker. In cranes withline contaetor on e tripple pole magnetic overload relayrated for total crane power may be provided to tripthe main contactor

Adjustable overload releases shall be provided to tripth e main contactors or circuit-breakers an d shall beconnected as close to them as possible. Th e minimumprovision for over current protection shall be as givenbelow:

a) one instan taneous release in a common linefeeding all motions se t to trip th e maincontactors or circuit breakers instantaneouslyw hen t he current rises to 25 0 percent of th e