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PRODUCT CATALOGUE

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oil seals

BRAMMING: Tel . +45 7656 2600HERLEV: Tel . +45 4485 8100


CONTENTS

3

Page

Introduction 4 Oil seal function 4 Sealing principle 4

Standard oil seals 5 DIN 3760 5 Conversion table 6 Dimensions and designations 6

Technical data 7 Choice of sealing material 7 Determining the right elastomer 7 Metal case 8 Spring 8 Pressure 8 Speed 8 Choice of correct lubricant 9 Leakage 9 Causes of leakage problems 10 Friction loss 10

Design and installation 11 Design of shaft and housing 11 Shaft 11 Housing 12 Fitting standard oil seals 12

Oil seals for special applications 13 Oil seals for pressure applications 13 Radial seals 14 Fitting radial seals 14 Split seals 15 Fitting split seals 15

Storage 16

Troubleshooting 17

Guide for choosing the correct oil seal 18


Oil SEalS

4 BRAMMING: Tel . +45 7656 2600HERLEV: Tel . +45 4485 8100

iNTrOduCTiON

Betech Seals was founded in 1922 and is today one of the market's leading suppliers of gaskets, seals, mouldings, bellows, vibration dampers, and sheet and plate work.

We offer a wide range of seals, including:• Oilseals• V-rings• Gammarings• Bondedseals• Sealingprofiles• O-rings• X-rings• D-rings• Squareseals• Backuprings

This catalogue provides relevant technical information on oil seals. The information is based on our own experience and should therefore beconsideredasrough,general,non-bindingguidelines.

We offer standard oil seals of type DIN 3760 with outside diameters of up to 1000 mm and radial seals with outside diameters of up to 2400 mm.Besidesstandardrubberqualities,weofferhighly developed special compounds suitable for demanding media and working conditions. We canalsodevelopnewmaterialstomeetcustomer-specific needs.

Oil seal functionOil seals are one of the most commonly used seals for dynamic sealing tasks. Oil seals are generally used to prevent oil from leaking in rotating applications, but can also be used in special circumstances to seal against leakage of other liquids,gases,powdersandgranules.

To ensure that the oil seal is given optimum working conditions, thus prolonging its service life as much as possible, it is important that the shaft surface complies with the recommended limits. To seal ball bearings and gears and to prevent leakage of lubricant and gases or ingress of dirt and dust, it is also crucial that the oil seal is designed correctly and made of suitable material.

Sealing principleThe area between the sealing lip and shaft is a critical part of oil seal design. The oil seal is pressed into a bearing housing, providing the requiredinterferencebetweenthehousingandthe outer surface of the seal. The oil seal is thus prevented from rotating and forms a static seal. Thesealinglipisequippedwithagarterspring,whichpressesthelipagainsttheshaftwithawell-defined pressure, optimising sealing efficiency and durability.

A thin film of fluid is formed between the sealing edge and shaft. Due to capillary force and the surface topography of the shaft, the fluid being sealed forms a meniscus under the sealing lip and is thus prevented from leaking.

Metal caseOuter sealing surface

Outer sealing surface

Front face of sealing lipSealing edge

Rear face of sealing lip

Dust lip

Garter spring

Spring groove

BRAMMING: Tel . +45 7656 2600HERLEV: Tel . +45 4485 8100 BRAMMING: Tel . +45 7656 2600HERLEV: Tel . +45 4485 8100

Oil SEalS

5

STaNdard Oil SEalS

DIN 3760AllouroilsealsconformtotheGermanDIN3760standardandtheISO9002qualitystandard.DIN3760describesgeneralrequirementsonoilsealdesign, dimensions and tolerances.

Betech Seals designation Description

SC Equippedwithrubbersheath,allowinguseinapplications with rough surfaces or high thermal expansion.Suitableforsealingagainstlow-viscosityand gaseous media. Easily replaced as fretting corrosion is prevented.

TC As type SC but with dust lip.*

SB2 Oil seal with metal case and vulcanised sealing lip. RequiressmoothersurfacethantypeSCtoachieveouter surface tightness. Often replaced by type SC.

TB2 As type SB but with dust lip.*

SA2 Oil seal with metal case similar to type SB but with additional reinforcement. Used primarily for large shaft diameters.

TA2 As type SA but with dust lip.*

DC Double sealing lip with two springs.

* Recommended for sealing against dirt, dust and moisture on air side.


Oil SEalS


Metal caseAs standard, the oil seal case is made of plain carbon steel and treated to prevent corrosion. Somespecialapplicationsrequireastainlesssteelcase however.

SpringAs standard, oil seals are supplied with a galvanised steel spring. Springs are, however, also availableinstainlesssteel,acid-resistantsteel,bronze or elastomer.

Dimensions and designationsOil seal dimensions are specified as shown in the example below:

Oil seal: OTRType: SCMaterial: NBR

Shaft diameter: d1 = 35 mmOutside diameter: d2 = 45 mmWidth: b = 7 mm

Stainless steel: SS

Designation: OTR SC NBR 35× 45× 7 SS

Conversion tableDIN Betech

SealsSimrit-Freudenberg

Gaco Dichtomatic Kako Simmerwerke Eriks SKF

3760A SC BA A WA DG A R HSM5

3760B SB2 B1 ABI WB DF B M CRW1

3760C SA2 B2 WC DFK C GV CRSH1

3760AS TC BASL FA WAS DGS ASL RST HMSA10

3760BS TB2 B1SL WBS DFS BSL MST CRWA1

3760CS TA2 BSSL WCS DFSK CSL GVST CRSHA1

3760AS-P TCV BABSL WASY RST-D

d1

b

d2


Oil SEalS

7

TEChNiCal daTa

Choice of sealing materialOil seals consist of a case and sealing lip. The case is made of either plain carbon steel or stainless steel while the sealing lip is made of elastomer.

Which material is most suitable? The choice of material depends on temperature, shaft speed, medium and the surrounding environment. As standard,thesealinglipismadeofoil-resistantNBR rubber. If, however, the seal is to be used in applications with high shaft speeds or aggressive media, a wide range of other materials that are more suitable for such conditions is also available.

Determining the right elastomer NBRAcrylonitrile Butadiene RubberNBR has low compression set and good resistance to hydraulic oils, diesel oils and mineral greases. As itcanwithstandneitherozonenorUVradiation,thematerial is unsuitable for outdoor applications. As NBRisaverygas-tightmaterial,itisoftenusedinapplications involving gas.

Brand name: Nitrile, BunaN®Temperature range:

–35 °C to +120 °C in oil / +90 °C in water

FPMFluorelastomerFPM has excellent resistance to mineral oils, aliphatic, aromatic and chlorinated hydrocarbons, concentrated and dilute acids and a wide variety of other chemicals. It is also resistant to ageing, ozone and weathering. On the other hand, FPM

becomes inflexible in cold environments and has relativelypoorresistancetopolarliquids(ketones,ethers and esters).

Brandname:Viton®Temperature range: –15 °C to +200 °C

QSiliconeThis elastomer can withstand both high and low temperatures and has low compression set.Siliconeisresistanttosunlight,oxygen,UVradiation and dry heat but cannot withstand most petroleum-basedliquids,ketones(e.g.MEKandacetone),steamorether.Siliconeisnotgas-tight.Silicone is not recommended for applications in which it comes into contact with hydrocarbons like petrol or paraffin or steam at pressures over 3.5 bar.

Temperature range: –60 °C to +200 °C

ACMPolyacrylateThis elastomer is suitable for high temperatures and mineral oils and is also ideal for oil additives, especially sulphur additives used for lubrication purposes under extreme pressures. ACM has good resistance to ozone, weathering and oxidation. ACM is often used in applications that combine high temperature and oil.

Temperature range: –20 °C to +130 °C

Maximum temperature (°C) of sealing mediumElastomer Min. temp. Engine

oilGearboxoilSAE

Hypoid oil ATF oil Grease Petrol Water Lye Brake fluid

NBR -35 100 80 80 100 90 90 70 70 -

ACM -20 130 120 120 130 * * - - -

Q -60 150 130 - * * * - - -

FPM -15 180 150 150 170 * 150 100 100 *

-Theelastomerisnotresistanttothesemedia.

* No guarantee of elastomer tightness can be given for these media.


Oil SEalS


Resistance table, elastomersresistance NBr aCM VMQ FPM hNBr PTFE

Wear 1 4 4 1 3 2

High temperature 3 Max. 100 °C

2 Max. 150 °C

1 Max. 180 °C

1 Max. 200 °C

2 Max. 150 °C

2 Max. 200 °C

Low temperature Down to –40 °C Downto-30°C Downto-50°C Downto-15°C Downto-40°C Downto-80°C

Oil (+hightemperature)

2 (max.80°Cinheavy-dutyoils)

2 3 (max.150°Coperating temperature)

(max.140°C operating temperature)

1

Chemicals 2 4 4 2 1

Price level Economical More expensive than NBR

Relatively expensive

Expensive

1= excellent 2 = good 3 = limited 4 = not recommended

Metal caseThe metal case or metal insert stiffens and strengthens the seal. Metal cases designed for standard oil seals are unsuitable for axial loads. In applications where the oil seal is exposed to axial loads,itisrecommendedthatthesealbeequippedwith a specially designed metal case.

Usually,thecaseismadeofcold-rolledsteelsheet(AISI1008,DIN1624).Inapplicationsthatrequireprotectionagainstcorrosionorchemicalattack,metalcasesofstainlesssteel(AISI304,DIN1.4301) can be used.

SpringAsstandard,oilsealsareequippedwithgalvanisedsteel spring. For applications where the seal must be capable of withstanding water or particularly aggressiveliquids,springsofstainlesssteel,acid-resistantsteel,bronzeorelastomerarealsoavailable.

If rubber is subjected to heat, loads or chemicals, it will gradually lose its initial properties. In other words, the rubber ages. The purpose of the spring is to ensure that the oil seal retains its initial radial strength.

GalvanisedspringsteelSAE1074,DIN17223Stainless spring steel AISI 304, DIN 1.4301

Pressure Iftheinternalpressureislowornon-existent(lessthan 0.5 bar), a standard oil seal of type DIN A, B or C should be used.Oil seals which are suitable for applications with

pressures of up to 10 bar can, however, also be designed.

Speed The peripheral speed, rotational speed and diameter of the shaft are important parameters when choosing the most suitable elastomer. Shaftperipheralspeed[V]isspecifiedinm/sandcalculated as follows:

V=d1xRxπ60.000

V: shaftperipheralspeed[m/s]d1:shaftdiameter[mm]R: rotationalspeed[rpm]

For guidance purposes, the diagram below indicates general guidelines for choice of elastomer at specific peripheral and rotational speeds.

10

500

1000

1500

2000

2500

3000

3500

400045005000600070008000900010001500020000

20

25

30

35

40404040

0000 20202020 40404040 60606060 80808080 100100100100 120120120120 140140140140 160160160160 180180180180 200 mm200 mm200 mm200 mm

123456789

rotational speed, shaft (rpm)

shaft diameter (mm)

perip

hera

l spe

ed, s

haft

(m/s

)


Oil SEalS

9

Choice of correct lubricantTopreventleakage,a1-3µmthicklayeroflubricantisrequiredbetweenthesealingedgeandshaft.

Thelubricantprovidesafilmofliquidthatformsaninterfacebetweenairontheonesideandliquidontheother.Iftheliquidfilmisbroken,leakagemayresult.

To obtain minimum friction, there must be a film of liquidbetweenthesealinglipandshaft.Thefilmacts as a lubricant, preventing friction and heat generation. The lower the temperature, the longer the expected service life of the seal. The sealing lip must never be allowed to dry completely. When used to seal oil or grease, the seal will seldom dry out. Similarly, oil seals adjacent to ball bearings will normally be lubricated sufficiently by the ballbearinglubricant.Whenusedtosealnon-lubricating media, the seal should be lubricated withoilorgreasebeforefitting.Withtwo-lippedordouble seals, the space between the two sealing lips must be filled with grease prior to fitting. Note though that the oil seal must be fitted in such a way as to prevent the creation of overpressure when applying the lubricant. To prolong oil seal service life, a certain amount of leakage should be accepted. In practice, however, such leakage will be so small as to be immeasurable. If an oil seal is allowedtodryout,itwillveryquicklyrupture.

LeakageLeakage can be categorised and defined in various ways.

Watertight: Noliquidpresentonshaft.

Damp: Beads of moisture near the sealing edge reduce sealing efficiency, but the other side of the surface area remains unaffected.

Wet: Beads of moisture, which also spread to the other side of the surfacearea.Dropsofliquidform but do not drip.

Measurable leakage:

Small beads of moisture on outer surface of housing, originating from rear side of seal.

Temporary leakage:

A transient problem with the sealing system, caused for example by small particles of dirt accumulating beneath the sealing edge. Such particles will be dislodged by subsequentuse.

Apparent leakage:

A problem caused by the lubricant between sealing edge and dust lip. The lubricant overflows, giving the impression of leakage on the outer face.


Oil SEalS


Friction lossCauses of leakage problems• Tolerancesconcerningtheinterferencebetween

the outer surface of the seal and the bearing housing have been exceeded.

• Therubberhascrackedbecauseoperatingparameters have been exceeded.

• Therubberhashardenedbecauseoperatingparameters have been exceeded or because it is incompatible with the media being sealed.

• Corrosionofshaftuptosealingedge.• Insufficientlubrication:Sealhasdriedoutand

sealing edge become worn. • Lumpsofoilhaveformedatthesealingedge.• Excessivevibrationofunitandshaftpreventlip

from forming tight seal. • Sealinglippermanentlycontaminatedwithdirt

arising from inside or outside the chamber. • Sealdamagedinconnectionwithhandlingor

fitting.

Friction lossFrictionnotonlyhasconsequencesfortheoilseal sealing lip. Excessive friction may also cause unintended power loss from the system.

Some friction loss is inevitable as the sealing principle of oil seals is based on the friction arising between the sealing lip and shaft where the two components are separated by a very thin film of liquid.Foranygivenshaftdiameterandrotationspeed, the friction coefficient depends on the friction between the actual oil seal and the shaft.

Measuring the precise amount of friction loss is difficult. However, the diagram in the next column illustrates the relationship between power loss, shaft diameter and shaft speed for standard oil sealswithstandardhigh-qualityoil(SAE30)at100 °C.

0,01000 2000 3000 4000 5000 6000

0,1

ø10ø20

ø30

ø50

ø60

ø70

ø80

ø400,2

0,3

0,6

0,4

0,5

shaf

t dia

met

er (m

m)

shaft speed (rpm)po

wer

loss

(hp)


Oil SEalS

11

If the shaft is to be fitted in direction y, it must be chamfered as indicated in the table below.

dESigN aNd iNSTallaTiON

Design of shaft and housing

Shaft Shaft surface finish is critical for the efficiency and service life of the oil seal. It is important that the shaft be free of helical grooves as these can transport the medium along the shaft and cause leakage. The problem can be prevented by rolling or plunge grinding the shaft surface.

Attheslidingsurface,shaftdiameter[d1]musthave ISO h11 tolerance. The recommendations below will help prevent the oil seal from being damaged during fitting:

If the shaft is to be fitted in direction z, any edges should be rounded as follows:

rmin. = 0.6 mm for oil seals without dust liprmin. = 1.0 mm for oil seals with dust lip

Chamferd1 d3 d1 d3 d1 d3 d1 d3 d1 d3 d1 d3

6 4.8 24 21.5 52 48.3 85 80.4 160 153.0 340 329.0

7 5.7 25 22.5 55 51.3 90 85.3 170 163.0 360 349.0

8 6.6 26 23.4 56 52.3 95 90.1 180 173.0 380 369.0

9 7.5 28 25.3 58 54.2 100 95.0 190 183.0 400 389.0

10 8.4 30 27.3 60 56.1 105 99.9 200 193.0 420 409.0

11 9.3 32 29.2 62 58.1 110 104.7 210 203.0 440 429.0

12 10.2 35 32.0 63 59.1 115 109.6 220 213.0 460 449.0

14 12.1 36 33.0 65 61.0 120 114.5 230 223.0 480 469.0

15 13.1 38 34.9 68 63.9 125 119.4 240 233.0 500 489.0

16 14.0 40 36.8 70 65.8 130 124.3 250 243.0

17 14.9 42 38.7 72 67.7 135 129.2 260 249.0

18 15.8 45 41.6 75 70.7 140 133.0 280 269.0

20 17.7 48 44.5 78 73.6 145 138.0 300 289.0

22 19.6 50 46.4 80 75.5 150 143.0 320 309.0

All values are in mm

fitting direction z fitting direction y

chamfer


Oil SEalS


Recommended surface roughnessTo achieve optimum sealing efficiency, the surface roughness of the shaft in the sealing area must be:Ra=0.2to0.8µm,R2=1to5µm,andRmax=6.3µm.

Low surface roughnessWhen surface roughness is lower than recommended(especiallyincombinationwithhighrotation speed) there is a serious risk that lubricant will be unable to reach the edge of the oil seal. This may cause premature ageing as the oil seal will be insufficiently lubricated. The rubber may become hard and brittle and begin to crack or fissure, and there may be signs of burning at the sealing edge.

High surface roughnessIt is important that surface roughness is not too high as this may cause excessive wear of the oil seal, reducing its service life. High surface roughness also increases the risk of leakage.

HardnessTo ensure sufficient service life, shaft hardness should be at least 45 HRC. At speeds exceeding 4 m/s, or with impure or abrasive media, shaft hardness should be at least 55 HRC.

Shaft run-outTo achieve optimum sealing efficiency, it is importantthatshaftrun-outispreventedandthatthe shaft is concentrically positioned in relation to the housing. As this is seldom possible in practice, compliance with the recommended values is important.Shaftrun-outcanbeminimisedbypositioning the oil seal as close to the bearing as possible.

Shaft run-out

Concentricity

HousingSteel and cast iron provide ideal surfaces for bothrubber-coatedandmetalseals.Forsoftalloys(e.g.aluminium),rubber-coatedsealsare recommended. Metal seals cannot be recommended for bearing housings of plastic or nylon.

Housing bore The housing bore should have a diameter of [d2]with ISO H8 tolerance and a surface roughness from Ra = 1.6 to 6.3, R2=10to20µmandRmax=25µm. Tofacilitatefitting,a5-10°chamferisrecommended.

Fitting standard oil sealsBefore fitting an oil seal, it is important to check that it is clean and undamaged. The shaft must also be smooth and undamaged. Damage to the oil seal or shaft is namely the most common cause of leaks.

shaft diameter d1 (mm)

250200150100 27522517512575502500,0

0,1

0,2

0,3

0,4

Con

cent

ricity

(mm

)

7000

NBR FPM ACM

Q

60005000400030002000100000,0

0,1

0,2

0,3

0,4

shaft speed (rpm)

shaf

t run

-out

(mm

)

Shaft run-out

Dynamic eccentricityLine of shaft centre rotation

Rotation centre

Shaft

Shaft run-outMax. shaft run-out

Shaft Bore centre-line

Rotation centre Housing bore

Concentricity


Oil SEalS

13

Oil seals must be fitted concentrically, perpendicular to the shaft. It is recommended that a fitting tool be used in order to facilitate fitting and reduce the possibility of faults. The sealing lip should usually face the medium to be sealed and must be able to move freely.

Oil SEalS FOr SPECial aPPliCaTiONS

Iftherequiredsealingdesigncannotbeachievedusing a standard solution, special oil seals are also available.

Oil seals for pressure applicationsStandardoilsealsareprimarilydesignedfornon-pressure applications. At peripheral speeds of less than 8 m/s, standard oil seals can, however, usually withstand pressures of up to 0.5 bar. At pressures greater than 0.2 bar and high peripheral speeds or pressures greater than 0.5 bar and low peripheral speeds, backup rings or specially designed oil seals should be used. Although backup rings can be used together with oil seals, we recommend the use of our specially designed oil seals for pressure applications.

Betech Seals designation

Description

SCV Reinforced sealing lip designed for overpressure

TCV Reinforced sealing lip designed for overpressure, with dust lip

The maximum permissible pressure depends mainly on shaft speed, temperature and lubrication.

Oils seals for pressure applications are characterised by a short, yet flexible, sealing lip. This particular design prevents surface pressure from increasing, thus limiting friction between the sealing lip and shaft.

Oil seals for pressure applications are also suitable in situations where pressure periodically fluctuates as the sealing lip prevents suction from the air side. In applications where low atmospheric pressure is part of the problem complex, the use of two oil seals is recommended, one with its sealing lip facing the air side.

The higher the pressure and shaft speed, the shorter will be the service life of the oil seal.

Diagram:OilsealtypeTCV.Permissibleoverpressure.

0

1

0 1000 2000 3000 4000 5000 6000 7000

2

3

4

5

6

7

8

9

10pressure (bar)

rpm

∅25

∅50

∅100

∅150

shaft diameter (mm)

Oil seals are also available to order with specially reinforced sealing lip capable of withstanding pressures higher than those indicated in the diagram.

If a backup ring is used in the application, a standardoilsealcanbeused.TypeTCVisrecommended in such cases.


Oil SEalS


Radial sealsRadial seals are rubber oil seals reinforced with fabric rather than metal. Radial seals are designed to seal ball bearings in rolling plants, paper mills, heavy-dutygearboxesandoffshoreapplications.As standard, radial seals are made of NBR, but are also available in FPM.

Advantages:- Precisionmachiningofhousingnot

necessary. - Easyfitting.- Noproblemswithcorrosion.- Easyreplacement.

Four types of radial seal are available, either split or unsplit:

Betech Seals designation

Description

D5 Standard profile with fabric insert reinforcement and grooves for ensuring optimum lubrication of sealing lip when fitted back to back

D5S As D5 but with dust lip.

D6 Similar to D5 but with grooves on entire profile.

D7 Withring-shapedflange in addition to grooves.

Fitting radial sealsRadialsealsaremanufacturedwithanover-dimensionedoutsidediameter[O/D].Thebearinghousingmustbeequippedwithaplatewhosepurpose is to exert a controlled axial pressure on the seal, thus ensuring that it remains precisely positioned within the housing.

Shaft• Toleranceofshaftdiameter:ISOh9• Surfaceroughness:R2=4µm• Surfacehardness:min.55HRC

Housing• Borediameter:ISOH8• Surfaceroughness:R2=16µm

d: Nominal shaft diameterD: Nominal bore diameterH: Seal heightL: Nominal bore depth

Split radial seals must be fitted with the seam at the top. Radial seals should not be used in applications wherethestaticliquidlevelishigherthanthelowestpoint of the seal.

In applications where two radial seals are fitted, the seams should be displaced 30° to either side of the shaft top. The bearing housing and shaft should be chamferedinordertofacilitatetrouble-freefitting

Plate


Oil SEalS

15

of the seal. The length and angle of the chamfer should comply with the following drawing and diagram:

b

a

shaft diameter shaft chamber

length (a)bore chamber

length (b)

1000800600400 120020000

a

b5

10

15

20

Split sealsSplit seals are dynamic seals with no metal case but with a metal spring and split design.

Split seals are used in applications where standard unsplit seals cannot be fitted over the end of the shaft because of flanges or bearings. Splitsealscanalsobeusedtominimisestrip-downcosts.

Fitting split sealsShaft• Toleranceofshaftdiameter:ISOh9• Surfaceroughness:Ra=0.5µm• Surfacehardness:min.55HRC

Housing• Borediameterincompliancewiththefollowing

table:

Shaft diameter (d)

Bore diameter (D)Tolerance

Bore depth (L)Tolerance

>140 mm ±0.12 ±0.05

140 – 200 ±0.15 ±0.07

200 – 300 ±0.15 ±0.10

300 – 450 ±0.20 ±0.12

< 450 mm ±0.20 ±0.15

Split seals should be fitted with the seam on top of the shaft. They should not be used in applications wherethestaticliquidlevelishigherthanthelowestpoint of the seal.

Clean the housing bore and remove all swarf and rough edges. Stretch the garter spring around the shaft. Join the ends of the spring by screwing the conical end into the hollow end. Position the split seal around the shaft and then stretch the garter spring into the groove. Compress the split seal slightly against the shaft to allow it to be inserted into the bearing housing. Begin easing the seal into the housing at the seam and press it into position all the way round. The bearing housing must be equippedwithaplatewhichexertsacontrolledaxial pressure on the seal, thus ensuring that it remains precisely positioned within the housing.


Oil SEalS


STOragE To prevent the material from ageing, the following guidelines should be observed when storing oil seals. In our experience, oil seals are best stored inadry,darkanddust-freeplaceatatemperatureof between +15 °C and +25 °C. It is also important to avoid storing the seals in the vicinity of ozone sources, e.g. electric machinery and direct sunlight. High humidity may cause some elastomers to deteriorate and metal cases and springs to rust. Oil seals should never be hung on nails or the like for storage. Wherever possible, they should be stored horizontally in their original packaging until being fitted. When oil seals are replaced, always follow the „first in, first out principle“ so as to avoid some seals being stored for an excessive length of time.


Oil SEalS

17

TrOuBlEShOOTiNg

Oil seals may leak at either of two critical points. One is located between the outer surface of the oil sealandthehousing(static),theotherbetweenthesealinglipandtheshaft(dynamic).

The table below summarises the various causes of leaks and our recommendations for remedying the problem.

Fault Cause Remedy

Oil seal rotates with shaft. Outside diameter of oil seal less than diameter of housing.

Replace oil seal with one of correct size.

Oil seal moves axially with shaft. Outside diameter of oil seal less than diameter of housing.

Replace oil seal with one of correct size.

Excess pressure causes oil seal to move axially.

Oil seal becomes deformed. Inside diameter of oil seal too small. Check size of shaft.

Damaged oil seal surface. Incorrect tool used for fitting. Use correct tool for fitting.

Damaged sealing lip. Insufficient lubrication. Lubricate sufficiently.

Design hampers lubricant transport to oil seal.

Change design to allow sufficient lubricant transport to oil seal.

Sealing lip partially damaged. Oil seal not concentrically aligned in relation to housing.

Centre oil seal using correct tool.

Sealing lip hard, cracked and worn. Excessive temperature, speed or pressure.

Choose correct rubber compound and oil seal type.

Insufficient lubrication. Lubricate sufficiently.

Sealing lip swollen. Incorrect choice of rubber compound. Choose correct rubber compound.

Sealing lip scratched. Surface roughness of shaft too high. Check surface roughness.

Incorrect tool used for fitting. Use correct tool for fitting.

Sealing lip collapsed. Oil seal incorrectly fitted. Ensure correct fitting.

Excessive pressure. Choose oil seal type suitable for high pressure.

Flex section cracked. Excessive pressure. Choose oil seal type suitable for high pressure.

Pressure exerted on flex section.

Spring lost position in groove. Insufficient groove depth. Choose alternative design or use spring with smaller diameter.

Oil seal incorrectly fitted. Ensure correct fitting.

Incorrect chamfer angle. Use fitting sleeve or chamfer shaft.

Leakage* Surface roughness too low/high. Alter surface roughness to recommended level.

Helical grooves, rust or other damage to shaft.

Repair or replace shaft.

*Leakage problems: see also section "Leakage"


Oil SEalS


Date:

Customer: Item no.: Application: Machine Transmission Other

Vehicleengine Agriculture

Wheel axle Marine

Drawing For reference only Sample For reference only Material specification Legislation

Special design

Type Size: Material: Additionalreq.:

APQP PPAP

Standard: DIN RMA JIS Acc. to customer specifications

Colour: GD(grindOD) PD(paintcolour) ND(nonGD/PD) GR(pre-greased) LF(lowfriction) Helix lip

Annual consumption:

Monthly consumption: Actual service life: Expected service life:

Shaft Diameter: Material: Surface roughness:

Hardness: Chamfer: Horizontal Vertical

Rotating Clockwise Anticlockwise Bi-directional

Normal:

rpm

Shaftrun-out:

TIR

Max.:

rpm

Misalignment:

M/m

Reciprocating Stroke length: Speed: Cycles/min

Oscillating Degrees of arc Speed: Cycles/min

Bore Diameter Material: Surface roughness: Depth: Installation:

Medium Internal: External: Temperature: ˚C/ ˚F

Min.:Normal:Max.:

Pressure: kg/cm2

psi bar

Normal:Max.:

Dry Wet Submerged

Air Light dust Mud Thick dust

guidE FOr ChOOSiNg ThE COrrECT Oil SEal


Oil SEalS

19

guidE FOr ChOOSiNg ThE COrrECT Oil SEal

Date:

Customer: Item no.: Application: Machine Transmission Other

Vehicleengine Agriculture

Wheel axle Marine

Drawing For reference only Sample For reference only Material specification Legislation

Special design

Type Size: Material: Additionalreq.:

APQP PPAP

Standard: DIN RMA JIS Acc. to customer specifications

Colour: GD(grindOD) PD(paintcolour) ND(nonGD/PD) GR(pre-greased) LF(lowfriction) Helix lip

Annual consumption:

Monthly consumption: Actual service life: Expected service life:

Shaft Diameter: Material: Surface roughness:

Hardness: Chamfering: Horizontal Vertical

Rotating Clockwise Anticlockwise Bi-directional

Normal:

rpm

Shaftrun-out:

TIR

Max.:

rpm

Misalignment:

M/m

Reciprocating Stroke length: Speed: Cycles/min:

Oscillating Degrees of arc: Speed: Cycles/min:

Bore Diameter: Material: Surface roughness: Depth: Installation:

Medium Internal: External: Temperature: ˚C/ ˚F

Min.:Normal:Max.:

Pressure: kg/cm2

psi bar

Normal:Max.:

Dry Wet Submerged

Air Light dust Mud Thick dust

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