# What is the final drive?

is the main component of the main reducer vehicle power train reduced speed, increased torque. The vertical position of the car engine, the main bevel gear reducer also used to change the direction of power. Later by a final drive gear speed down, to obtain a relatively high output torque, resulting in a large driving force.

### 1 main reducer noun

main reducer is reduced speed in the vehicle drive train, the main increase of the torque member. The vertical position of the car engine, the main bevel gear reducer also used to change the direction of power. Later by a final drive gear speed down, to obtain a relatively high output torque, resulting in a large driving force.

### 2. The main reduction effect

in the presence of the main gear unit has two functions, the first is to change the direction of power transmission, the second is to provide each of the transmission gear position as an extension of a common drive ratio. The output of the transmission is a moment about the longitudinal axis, the wheel must be rotated about the transverse axis of the vehicle, which requires a means to change the power transmission direction. The reason is called final drive, a factor that is because no matter what gear transmission on the transmission of this device is more than the total gear ratio. With this ratio, can effectively reduce the requirement for deceleration of the transmission capacity, benefits of this design is effective to reduce the size of the transmission, so that the overall arrangement of the vehicle is more reasonable.

final drive car the most important role is to slow down by twisting. We know the output power of the engine is constant, according to the power calculation formula W = M * v (power = torque * speed) When the gear speed reducer through the main down, to obtain a relatively high output torque, to thereby obtain greater driving force. Moreover, the final drive automotive power output also changes direction, the left and right wheels to achieve the speed differential or rear axle differential function.

### 3. The final drive type

● number of classes

by the number of the sub-participation reduction drive gear classification, can be divided into single-stage and two-stage final drive the final drive. In addition to requiring a large number of gear ratios, a heavy vehicles two-stage final drive, in general, micro-light, the car substantially single-stage final drive.

(1) a dual-stage gear

When the main drive gear unit is relatively large, having automobile in order to ensure a sufficient ground clearance is required at this time the two-stage final drive. A plurality of two-stage reducer intermediate transmission gear, the active portion of the vertebral engagement left bevel gear and the intermediate gear, meshing with a bevel gear coaxial with a small diameter spur gear, spur gear and the driven gear. Such intermediate gear to turn back, forward rotation driven gear. There are two intermediate deceleration. Double reduction volume increases since the axle, past mainly used in the low vehicle match engine power is now mainly used in low speed high torque mechanical engineering.

In the dual-stage final drive, when a second reduction stage carried out in the vicinity of the wheel, in fact constitute a separate member at the two wheels, the wheel speed reducer referred to. Such advantage is made possible to reduce the torque transmitted by axle, it is advantageous in reducing the size and quality of the axle. Wheel reduction gear may be a planetary gear type, may be constituted by a pair of cylindrical sub gears. When using the sub-wheel reduction gear may be cylindrical by adjusting the mutual position of the two gears, the positional relationship between the change the vertical axis of the wheel axle. This axle is called portal axle, commonly used in special requirements for high and low position of the vehicle axle.

(2) Single-stage gear

single stage gear reducer is an active vertebrae (commonly known as the angle of the teeth), and a driven bevel gear (commonly known as Crown gear), the active gear vertebral connecting shaft, rotating clockwise, driven bevel gear attached to the right side thereof, the engagement point is rotated downwardly, the same direction with the wheel forward. Since the diameter of the driving bevel pinion gear, driven bevel gear having a larger diameter, reaches the deceleration function.

● gear ratio by the number of bins

by the number of gear ratios of the main gear can be divided into single-speed and two-speed type two. At present, domestic car basically using a single fixed speed type main gear ratios. In the two-speed type main speed reducer, provided with two alternative gear ratios, final drive actually has such functions as the auxiliary transmission.

● by structure type

by a reduction gear subStructure type can be divided into cylindrical gear, bevel gears and hypoid gears and other types.

In the engine transversely disposed axle drive motor vehicle, often using simple main reducer helical cylindrical gear; longitudinally arranged in the engine vehicle drive axle, often using a final drive and hypoid bevel gear and other gear types. Compared with the bevel gear, hypoid gear work better stability, higher flexural strength and contact strength, but also with respect to the axis of the main driving gear driven gear axis offset.

When the drive gear axis shifted downwards, the position of the drive shaft can be reduced, thereby facilitating a reduction of the vehicle body and the vehicle center of gravity height and improve vehicle driving stability. A final drive

Modern cars, widely used spiral bevel gear and the hypoid gear. When hypoid work, the pressure between the sliding surface and the larger tooth, the tooth surface film susceptible to damage, must be lubricated hypoid gear oil, gear oil must not be allowed ordinary place, otherwise the tooth surface would quickly wear and abrasion and greatly reduce service life.