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Ceramic balls

· Add:1904, No.11, Jianwai
          SOHO, 39 East 3rd-Ring
          Road, Chao Yang District,
          Beijing, China
· Tel: +86 10 81572284
· Fax: +86 10 81572284


Auto water pump bearings

As the automobile's core ,the engine is improving with high efficiency, so to the water pump bearing, we need more high requirements, for example, more load,and more high anti-heat, and better seal.

XLB-water pump bearing is that new style of bearing fitting for these requirements. In the fact, it is a kind of simple double-load bearing. The double-load bea-ring has no inner ring, the race-way of roller is on the shaft directly. The two load bearing forms a whole , both side of the outer ring sealed with seal . At the same load condition, the size of radial load is smaller than other bearings. And the same axial load condition, the ability of load is high than other bearings . Because of good-hard ,high accuracy of rotate, simple structure, and easy dismounting, many countries, like AMERICA, JAPAN, and GERMAN all use this kind of structure. XLB develops all kinds of water pump bearing and they are used in automobiles that made in our China.

Water pump is formed by outer ring, water pump bearing, anti-water seal, impeller, fan and rollers.water pump bearing is the most important part of the water

pump. Because the high speed of revolution, usually it reaches 9000r/min, it requiresthe high-load ability ofwater pump bearing. And only this can guarantee the life of

bearing under the high speed revolution. Because of the limited space, bad operation condition, thewater pump bearing should assure the normal revolution requirement,

and the same time can decrease the bearing's ability of load. Itis difficult for the seal of bearings , beacuse the reliability and the wear ability of the bearing will effect the

usage of the bearing. Totally, loading ability, operating seal and operating clearance, are the importand factors effecting the capability of the bearing.

Material and heating treatment

The ball and the roller of XLB are all made by high chrome steel, and shaft, outer ring uses carbon steel or chrome steel. Usually, if the shaft material is high-carbon, the hardness reaches 60-64HRC. And if the shaft material is high-chrome, the hardness reaches 58-62HBC. The hardness of ball and roller reaches 61-65HRC. And the hardness of outer ring is 60-64HRC.

Lubrication and Seal

XLB water pump bearing use once-time lubrication and also it is a kind of lifetime lubrication. It is normal for a small quality of grease to come out of the seal lip.This quality should be 1/4 or 1/2 part of the space. In usual condition, NO 2# or NO 3# grease can satisfy the requirement of lubrication, but when the temperature is higher than 120℃.We should use high-level grease.
The function of the waterpump bearing seals is to exclud contaminants,such as dust or coolant vapour,while retaining the lubricant.It is normal for a small quantity of grease to come out of the seal lip,as part of the lubrication of the seal lip interface.This quantity should not exceed 0.2g.The seal performance is determined by thematerial properties and the lip design, as detailed below.
Auto water pump bearings

Conventional single lip snap type design

1.For normal automotive applications
2.Vulcanized elastomer sealing element
3.Ease of assembly
Auto water pump bearings

Standard double lip interlocking design

1.For demanding applications
2.Inward facing seal lip for improved grease retention
3.Upgraded rubber material for better sealing against coolant
4.Positive lock in outer ring,reduces possibility of seal spinning
5.Optimized lip cross-section for torque and sealing performance
Auto water pump bearings

Triple lip interlocking design

1.For severe applications
2.Inward facing seal lip for improved grease retention
3.Upgraded rubber material for better sealing against coolant
4.Positive lock in outer ring,reduces possibility of seal spinning
5.Optimized lip cross-section for torque and sealing performance
6.Additional stainless steel slinger and third lip for increased sealing potrction


The intenal bearing clearance in rolling bearings in operation greatly influences bearing performance in terms of fatigue life ,vibration ,

noise,heat-generation ,ect. Conaequently ,theselection of a proper internal clearance is one of the most important tasks .

Theoretically,the longest bearing life can be expected when the clearance is slightly negative.However ,it is difficult to achievesuch an ideal condition,and an excessive negative clearance will greatly shorten the bearing life.Therefore,a clearance of zero ora slightht positive amount,

instead of a negative one ,should be selected in general.

When choosing the clearance, we should not only consider the decrease of the clearance, because of the interference fit between the outer ring and bearing seating, but also should consider the decrease of the clearance, because of the increasing of the tempe-rature. The shell of the water pump bearing has two kinds of shell, one is iron, another is aluminum. The fit of the water pumpbear-ing and shell is interference fit (For list one).

XLB bearing has no special requirements. The radial clearance is 15-35μm. NSK water pump bearing's radial clearance is 10-40μm.FAG is 10-36μm.

Maintenance and mounting

Comparing with the normal part of machine, the water pumpbearing is a precise part. So we should be careful when we keep.

XLB water pump bearing all use the package of anti-rust and the anti-rust oil. Only the package is not destroyed,the quality will be assured. The best maintenance condition is that the temperature is 20℃ or so, the moistness is 65%,and should keep the shelf about 30cm above the ground. And should keep away the sunshine and the cold wall.

When mounting the bearing into the housing, care must be taken to prevent the transmitting of forces through the ball complement. In order to avert this , a sleeve should be used that contacts the outer ring face only. A mechanical press should be used . The hub , impeller and mechanical seal bores must be aligned with the shaft axis during their mountin. Again a press should be used and the opposite shaft end must be supported to prevent transmission of forces through the ball complement.

The function of the outer ring interference fit is to retain the bearing in the housing over the intended service temperature range.It also must provide adequate bearing support without inducing ovality into the raceways.If the interference fit is too light ,the bearing could walk out of the housing.If the fit is too heavy,pre-load of the bearing may occur.
Auto water pump bearingsAuto water pump bearings

Housing requirements

Bore circularity<0.010mm.Bore taper<0.007mm per 25mm bore length.


During press in ,material from the housing bore is removed resulting in less holding force.In cold conditions,material removal increases.This depends on the housing material and the housing bore surface finish.

Lack of attention to proper installation of pulleys,fans,fan spacers or viscous clutches will cause increased bearing loading during operation.
Typically,the water pump belt forces and weights of rotating components on the bearing shafts will load the outer ring raceways over only one-half of its circumference.This is called a point loaded condition.Because of rotation with repect to the loads.the shaft receways are loaded over their full circumference or ,circumferentially loaded.If the assembly procedure or mounted components contain or induce eccentricities at the mating surfaces,imbalance loads will be generated.If angularity occurs,

gyroscopic moments are created due to the tilted,wobbling motion of the misaligned components during rotation.Angularity may also contribute to the eccrntric imbalance loads.All eccentric and gyroscopic load components are non-stationary in direction and rotate with the shaft.This situation,if severe , will reverse the raceway loading patterns to that of point loaded shaft receways and 360 degree circumferentially loaded outer ring raceways.The magnitudes of these loads increases with the square of the rotational speed.Other conditions generated under these circumstances are roller edge stressing and misaligned ball row tracking.

This acts to elevate cage and lubricant stressing and increase bearing operating temperatures.As well ,the L10 bearing fatigue life becomes shorter dueto the increased equivalent load on each row.Taken to extremes,imbalance and gyroscopic loads may become so high reaching the strength limitations of the shaft material.The dynamic stress reversals may initiate tiny mico-cracks in the hardened case layer.If operation such as this continues,the cracks will propagate across the entire shaft cross section and cause the shaft to fracture,often with catastrophic results.
Auto water pump bearings

WB Series

WR Series

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