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How are bearings used in automobiles?

Mar 10, 2020

In order to reduce the breakdown and improve the performance of automobile, the performance of bearing is more and more important. Now, about 100-150 bearings are playing a role in the vehicles with mainstream engines. In this paper, we take the automobile transmission and differential gear as an example to explain how the bearing is used in the automobile.

Figure 1 device for transmitting engine power to axle

Bearings used in transmission

In the transmission, different types bearings play their own characteristics. In the automobile parts, many bearings are also used.

Transmission can be divided into manual transmission and automatic transmission. In vehicles with manual transmission, the operating lever is set in the driver's seat.

Fig. 2 operating lever for manual transmission

The operator manually operates the gear lever to change the engine power into driving force suitable for driving conditions.

The manual transmission consists of shaft and gear. The bearing supporting these parts is described below.

Figure 3 structure of manual transmission

Figure 4 principle of manual transmission

Bearing of support shaft

According to the power of the engine, the appropriate type of bearing is used to support the rotation of the shaft and the force generated by the gear.

Table 1 bearing of support shaft

Radial load

Axial load

Bearing Type



Deep groove ball bearing



Cylindrical roller bearing



Tapered roller bearing

Fig. 5 deep groove ball bearing of supporting shaft

Bearing of supporting gear

In manual transmission, the gears are always meshed and rotated with each other.

To transfer the driving force suitable for driving to the axle, select the gear (a) suitable for the driving force through the operating lever. The selected gear (a) is connected to the shaft and rotates at the same speed as the shaft.

When the driving conditions change and different driving forces need to be transmitted to the axle, the gear (a) connected with the axle is removed from the axle through the operating lever, and the gear (b) suitable for different driving forces is selected. The selected gear (b) is connected to the shaft and rotates at the same speed as the shaft.

At this time, the rotation speed of the gear (a) leaving the shaft is different from that of the shaft.

In order to make the gear and shaft rotate at different speeds, a needle bearing (the assembly of needle roller and cage) is installed between the gear and the shaft to roll between the inner diameter surface (inner side) of the gear and the outer diameter surface (outer side) of the shaft.

Fig. 6 speed of variable speed gear and shaft

Bearings used in differential gears

When the car turns left and right, it will reduce the rotation speed of the inner axle and increase the rotation speed of the outer axle.

The differential gear is a device that transforms the driving force from the transmission into a larger driving force and transmits it to the left and right axles to realize different speeds.

Figure 8 wheel rotation when turning

The differential gear is installed on the pinion shaft (the shaft on the transmission side) and the gear on the shaft on the axle side to engage vertically. The bearings support the rotation of the shaft and the forces generated by the gears.

Figure 9 principle of differential gear

Figure 10 structure of differential gear

Tapered roller bearing of supporting shaft

The combined tapered roller bearing supports both the radial load and the axial load in both directions to ensure the correct engagement of the gears and transfer the large driving force to the left and right axles.

Figure 11 low torque tapered roller bearing

"SKET" is a registered trademark of sket bearing company. SKET is a small but professional tapered roller bearing manufacturer and supplier in China. SKET Tapered Roller Bearings has being exported to Western European market for 10 years.


This paper introduces the bearings used in the device that transfers the engine power to the axle, but there are many other parts of the car also use a lot of bearings. Each bearing gives full play to its own characteristics and improves the driving performance and safety of the car.

In order to further improve the safety and comfort of the car, the performance and reliability requirements of the bearing will continue to improve in the future.

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