Couplings Selection

8/10/2019 Couplings Selection

1/43

Coupling Selection


2/43

Contents

Essential Information Required

Service Factors

Coupling Ratings

Choosing a coupling arrangenment

Question Examples

Additional Checks

Special requirements

Selection Tools


3/43

Coupling Selection

Driver Machine

Driven Machine

Power (HP or kW ) Normal Max. Transient or Torque (Nm or lbs.ft) if available

Speed (rpm) Normal

Maximum if available

Distance between shaft ends (DBSE) (mm or inches) Driving and Driven shaft types and diameters

Essential Information for selection


4/43

Select a suitable SERVICE FACTOR

In coupling design the basic stress analysis considersthe Steady- torque condition.

Time


5/43

SF=3

Time

2. Cyclic Torque

(eg. Reciprocating comp.)

Time

SF=11. Steady Torque(eg. Centrifugal compressor)

Select a suitable SERVICE FACTOR

Knowing the DRIVEN & DRIVING machinery

What is a service factor ?

A multiplication factor applied to the nominal rating which allows for

CYCLIC TORQUE applied by certain machinery.


6/43

Service Factors

LOAD CLASSIFICATIONS: SERV. FAC. Continuous & uniform operation 1.0

(Infrequent starts/ Low starting torques)

Continuous operation with minor torque 1.5

fluctuations or frequent start/stop cycles

Torque loading varies during operation in 2.0

conjunction with some shock loading

Substantial torque fluctuations & heavy 2.5

shock loads


7/43

Allowable alternating Torque

450

500

600

700

800

Stressrange(Mpa)

Fatigue limit

103 104 105 106 107 108 109

Number of Cycles

400

Time

Stress

Stress

range

Tension (+)

Compression (-)

0

S-N Curve


8/43

Modified Goodman Diagram

0

200

400

600

800

1000

1200

0 500 1000 1500

Steady stress

A

lternatingstress


9/43


0

200

400

600

800

1000

1200

0 500 1000 1500

Steady stress

A

lternatingstress


10/43

Steady stress

Al

ternatings

tress

MEAN TORQUE

(MAX)

SPEED

(MAX)

(MAX) AXIAL

DEFLECTION

FRETTING LIMIT

RATEDOPERATING

POINT



11/43

Determine Coupling RATING

Determine the coupling Rating in kW/1000 rpm from thefollowing formula:

Given: Power (kW) and Speed (rpm)

Rating = kW x 1000 x SFN

where

SF is service factorkW is power rating

N is shaft speed


12/43

Choose Coupling Arrangement

The coupling arrangement will depend upon: available DBSE (distance between shaft ends)

bearing arrangement of the coupled machines

allowable overhung moment

mating interfaces with the shafts

special features required


13/43

Choose the coupling arrangement

required to suit the application

SINGLE BANK NON-SPACER

COUPLINGS

LDE0, LSE0, MHSO

CLOSE COUPLED ARRANGEMENTS

MODO, LDEC, LSEC

TSKC, TSNC, TSRC, TSE1


14/43

Choose the coupling arrangement

required to suit the application

STANDARD SPACER COUPLINGS

MHSS,

LSES, TSKS, TLKS, TSCS, TLCS

TSJE; TLJE; TTJE

MINIMUM OVERHUNG MASS

TSGE, TLGE, TTGE

TSDE, TLDE, TTDE


15/43

Bearing arrangements

Equipment design

XX X

3 Bearing

X XXX

4 Bearing

X Bearing


16/43

Misalignment and 3 Bearing System

XXX

Parallel offset

XXX

Converted to angular

X Bearing


17/43

4 bearing systems and misalignment

XX X X

Parallel offset

XX X X

Converted to angular at each end

X Bearing


18/43


19/43

Misalignment Capability

Non Spacer

Spacer

Axial and Angular

Misalignment Only

Axial, Angular and Lateral

Misalignment


20/43

Question 1

Steam Turbine to Centrifugal Compressor

6MW @ 10000 RPM

What is the required rating?


21/43

Answer to Question 1

Required Rating = kW x 1000 x SFN

Rating kW/1000 rpm = 6000 x 1000 x 1.0

10,000

= 600 kW/1000 rpm


22/43

Choose Coupling Arrangement

The coupling arrangement will depend upon:

available DBSE (distance between shaft ends)

bearing arrangement of the coupled machines

allowable overhung moment

mating interfaces with the shafts

special features required


23/43

Decide on the type of disc design

T series is the prime selection unless otherwise specified.

T series maintains the drive on disc failure through emergency drive

collars.

M series disconnects the drive on disc failure.

For API 671 requirements generally use T series.


24/43

Choose the coupling arrangement required

to suit the application

SINGLE BANK NON-SPACER COUPLINGS

LO, MHSO

CLOSE COUPLED ARRANGEMENTS MODO

TSRC, L***-*C, TSKC, TSKD


25/43

Choose the coupling arrangement required

to suit the application

STANDARD SPACER COUPLINGS

MHSS, MODS

L Series, TSKS, TLKS,

TSJE; TLJE; TTJE

MINIMUM OVERHUNG MASS

TSGE, TLGE, TTGE

TSDE, TLDE, TTDE


26/43

Coupling size

From the appropriate catalogue select the coupling for thecalculated rating.

Always select a coupling with a higher rating:

eg.Calculated rating: 211kW/1000rpm

Select: TSKS 0230


27/43

Question 2

Electric Motor to Screw Compressor

1500KW @ 3000 RPM

What is the rating?

Select a coupling


28/43


Required Rating = kW x 1000 x SFN

Rating kW/1000 rpm = 1500 x 1000 x 1.5

3,000

= 750 kW/1000 rpm

Select a TLKS-0750 or L081


29/43

SERVICE FACTOR for TRANSIENT

TORQUE

Standard couplings are suitable for transient torques as follows:

M-series up to 3 times continuous rating.

TSK up to 2.5 times continuous rating.

TLK up to 2 times continuous rating.

High Performance up to 2 times continuous rating.

To calculate the required coupling rating for Transient torque

Required Rating = Transient torque/f

where f is the factor given above

Example: Generator drive has a transient torque of 7 x nominal rating.For TLKS selection the minimum service factor is 7 / 2 = 3.5


30/43

Steam Turbine to Generation set through a 3:1 ratio

Steam Turbine 5MW @ 5400rpm

Generator set 5 x Continuous torque

Select gearbox to generator coupling

Question 3


31/43


Steam turbine 5MW @ 5400rpm = 5000kW @ 5400rpm

Generator 5000kW @ 5400/3 = 1800rpm

Steady duty SF generator = 1.5

Prime Mover, steam turbine = no change BUT

Gearbox present so minimum SF = 1.25

Required Steady service factor = 1.5


32/43


33/43

Additional checks

Speed Check that the application maximum speed is within the

permitted range for the coupling.

Dimension

Check that the hub maximum bore is adequate for eachshaft. Use a large hub or use a larger coupling if

necessary.

Check that the shaft end separation [DBSE] is acceptable

for the design chosen.


34/43

Coupling Selection

Shaft end types

Cylindrical (Straight) with key

W

Key height

Keyway height

(hub)

Keyway height

(shaft)


35/43

Coupling Selection

Shaft end typeConical (Tapered) with key

Required counter boreor across corners of

shaft nutTaper

(Ratio, in/ft or degree)

Key details

Size

Parallel to taper or

centerline


36/43

Question 4

Electric Motor to Centrifugal Pump Motor shaft - Parallel B + K

Pump shaft - Taper B + K Dia 36 @ large end

Shaft end separation 100mm

Power absorbed by pump 17KW

Motor Speed 2980

Selection + Assumptions made + Limitations


37/43


Duty Conditions

17kW @ 2980rpm; DBSE =100:

Is pump centrifugal? If so assume SF = 1

Rating kW/1000 rpm = 17 x 1000 x 1.0 = 5.7 kW/1000 rpm

2,980

Select either

>> MHSS-0006 or L001 or TSKS-0013

Pump shaft diameter = 36 mm taper OK for TSK and MHS, but L series

Re-select L003

Motor shaft diameter = ?? STATE maximum for selection

Clarify requirement.


38/43

Question 5

Motor 1500KW @1500 rpm 220 shaft

Gearbox 2.6 : 1 increasing, motor side 200 mm diameter

145mm pump side.

DBSE 200mm motor side, 140mm DBSE pump side

AP1 610 Select High speed coupling


39/43


Motor 1500kW at 1500rpm

Gearbox increasing pump speed to 1500 x 2.6 = 3900rpm

Shaft diameter GearBox(driver) = 145 mm

Pump shaft diameter = 140 mm

DBSE = 200mm

1500 x 1000 x 1.25

3900

TLKS-0750-0078-2000


40/43

Required Misalignment

Axial Misalignment (in / mm)

Angular deflection deg Parallel Offset (in / mm)

Industrial or Customer specifications apply?

(API 610, API 671, etc.)

Is this a new or retrofit application?

If retrofit, obtain mass elastic data of original coupling

Special requirements

Coupling Selection


41/43

Enquiry form

Shaft Length Shaft Length

B & K(driver)

B & K(driven)

DRIVEREND

DRIVENEND

D.B.S.E Tol

Shaft LengthShaft Length

Recess Diameter

TAPER KEY DETAILSParallel To AxisParallel To Bore

TAPER BORE DETAILSEnd: Large / SmallShaft: TolTaper Angle:

DRIVER / DRIVENEND

DRIVER / DRIVENEND

B & K(driver / driven)

B & K(driver / driven)

D.B.S.E

Recess Depth

TAPER KEY DETAILS

Parallel To BoreParallel To Axis

TAPER BORE DETAILS

Shaft: TolTaper Angle:

B & K(driver)

Shaft Length

Recess Depth

Recess Depth

D.B.S.E

Recess Diameter

Recess Diameter

DRIVEREND

DRIVENEND

Shaft Length

B & K(driven)

TAPER KEY DETAILS

Parallel To BoreParallel To Axis

Taper Angle:Shaft: T ol

End: Large / Small End: Large / SmallTAPER BORE DETAILS

METASTREAM COUPLING ENQUIRYENQUIRY REF:CUSTOMER:

PLANT / CONTRACT REF:

CONTACT: DATE:

FAX: PHONE: E.MAIL

SELECTION DATA

DRIVING MACHINE: DRIVEN MACHINE:

DRIVER RATING: kW / HP DUTY SPEED: rpm

SHAFT END SEPARATION (DBSE)

mm / in

SERVICE: (e.g. cooling water pump)

AMBIENTTEMPERATURE

-15oC to + 150oC YES NOIF NO - PLEASE SPECIFY oC / oF

APPLICABLESPECIFICATION

API 610 API 671 NONEIF API 610 OR 671 PLEASE SPECIFY EDITION:OTHERS (PLEASE SPECIFY)

PREFERRED COUPLING TYPE

OPTIONAL FEATURES (PLEASE TICK). PLEASE SPECIFY BALANCE GRADE IN BOX GIVEN

TAPPED PULLER HOLES PROFILED HUBS AXIAL ADJUSTMENT

INSULATED SPARK RESISTANT LIMITED END FLOAT

TRIM BALANCE HOLES BALANCED BALANCE GRADE G

TRANSMISSION BALANCE HUB BALANCE ASSEMBLY BALANCE

TORSIONAL TUNING SHEAR PIN FEATURE VERTICAL

REMARKS

TYPE SIZE FEATURES D.B.S.E.COUPLINGSELECTION

ORIGINATOR: DATE:

John Crane UK LtdSales and Service Division

Nash Road, Trafford Park,

Manchester. M17 1SS.

Tel: 01 61 872 2484

Fax: 0161 886 6335 or 5910

PLEASE SUPPLY DIMENSIONS USING CORRECT SKETCH: -

Tol

Tol


42/43

Selection Software


43/43

Selection Software

Documents

Couplings Selection