Kamaz final drive

The main gear serves to increase the torque on the drive wheels and transfer it from the cardan shaft to the axle shafts at a right angle.

The constant increase in torque is characterized by the final drive ratio

The total gear ratio of the entire transmission is the product of the gear ratios of the gearbox, transfer case and final drive and can be changed by engaging different gears.

The total gear ratio shows how many times the speed of the drive wheels is reduced compared to the speed of the engine crankshaft.

The larger the gear ratio, the greater the traction force developed on the driving wheels of the car.

Final drive and intermediate drive axle differentials

Depending on the purpose of KamAZ vehicles, the design of the bridges provides for four options for final drive gear ratios.

Gear ratios 7.22; 6.53; 5.94 are intended for vehicles operating as part of road trains, and gear ratios are 6.53; 5.94 and 5.43 - for single cars.

On KamAZ vehicles, two-stage main gears are used, consisting of two gear pairs, a pair of bevel gears with oblique teeth and a pair of cylindrical helical gears.

Changing the gear ratio of the main gear is achieved by installing gears of a cylindrical pair with a different number of teeth.

When driving on a rough road and when turning, the driving wheels of the car cover different distances in the same time intervals.

If the drive wheels were connected to each other by a common shaft, then in all cases of movement they would rotate at the same frequency, which would inevitably lead to slipping and slipping of the wheels relative to the road.

Slippage causes increased tire wear, increases power consumption, increases fuel consumption and makes turning difficult.

To avoid these disadvantages, the drive axles are equipped with a differential, which allows the drive wheels to rotate at different frequencies relative to each other.

However, it should be borne in mind that when driving on a slippery road, the presence of a differential contributes to the car skidding.

On KamAZ vehicles, a conical symmetrical cross-axle differential is used in each drive axle.

This means that bevel gears are used in the differential and the same torque is transmitted to the right and left wheels from it.

Cross differential

A center differential is also installed on the intermediate drive axle of KamAZ vehicles with the wheel formula: 6X4.

It allows the main drive shafts of the intermediate and rear axles to rotate at different frequencies, and therefore the wheels of these axles can also rotate at different frequencies.

The center differential of the car is conical, symmetrical, lockable.

When the differential is not locked, it distributes torque between the main gears of the intermediate and rear drive axles almost equally.

Differential coupling provides more uniform loading of the drive parts to the drive wheels, reduces tire wear, and improves vehicle handling.

In difficult conditions and on slippery roads, the presence of a differential adversely affects the vehicle's patency.

Under these conditions, it is blocked, the drive shafts of the main gears of the drive axles are rigidly connected and rotate at the same frequencies.

At the same time, the slipping of the drive wheels decreases, and the vehicle's cross-country ability increases.

The main gear of the intermediate drive axle of cars with wheel Formula 6X4 is carried out with a passage hall for the drive of the main gear of the rear axle.

The drive bevel gear 20 (Fig. 1) is installed in the neck of the main gear housing on two roller tapered bearings 24, 26, between the inner races of which there is a spacer sleeve and shims 25.

The splined end of the hub of this gear is connected to the bevel gear of the center differential, and inside the hub there is a drive shaft 21, connected at one end to the bevel gear of the center differential, and at the other end, with the help of a driveline, to the drive shaft of the main gear of the rear axle.

Rear axle final drive and differential

The intermediate shaft rests at one end on two tapered roller bearings 7, between the inner races of which there are shims 4, and on the other end on a roller bearing mounted onth in the bore of the bulkhead of the crankcase.

Tapered roller bearings 7 secure the intermediate shaft against displacement in the axial direction.

Along with the intermediate shaft, a spur gear 3 with oblique teeth is made.

Driven bevel gear 1 is located at the end of the intermediate shaft and is kept from turning by a key.

The driving and driven bevel gears of the main gear are selected at the factory in sets, ground and branded, indicating the serial number of the set.

The driven spur gear 16, fixed in the axle differential housing, rotates on tapered roller bearings 9. These bearings are adjusted by nuts 8.

Between the halves (cups 1 and 8) of the differential housing (Fig. 2.) in the plane of the connector, a crosspiece 5 is clamped, on the spikes of which four conical satellites 7 are freely installed, each of which is engaged with two side gears 4 installed in differential housing.

All differential gears are spur gears.

The ends of the satellites and their bearing surfaces in the differential housing are spherical, which ensures the necessary centering and proper engagement of the satellites with the gears of the axle shafts.

To reduce friction and the likelihood of scoring, floating support washers 3 and 2 are installed between the differential housing and the ends of gears 4 and satellites 7.

Washers are selected to a certain thickness when assembling the differential.

The half shafts of the drive wheels are connected to the corresponding side gears using splines.

The transmission of torque from the center differential is carried out to the driving bevel gear 20 (see figure), then to the driven bevel gear 1, the driving spur gear 3 and the driven spur gear 16.

The torque from the body of the cross-axle differential, to which the driven spur gear 16 of the main gear is attached, is transmitted to the crosspiece 15, and from it through the satellites to the gears of the axle shafts.

The satellites 7 (Fig. 2), acting with the same force on the right and left gears of the semi-axes, create equal torques on them.

At the same time, due to insignificant internal friction, the equality of moments is practically preserved both with stationary satellites and with their rotation.

Turning on the spikes of the cross, satellites provide the possibility of rotation of the right and left axle shafts, and consequently, the wheels with different frequencies.

Lubrication of the rubbing surfaces of the main gear and differential parts is carried out by spraying the oil in the crankcase.

Lubrication enters the differential through windows in its housing, and longitudinal and radial channels are provided in the cups in which the bearings are installed to supply oil to the tapered bearings of the drive bevel gear and the intermediate shaft.

The cavity of the main gear case communicates with the atmosphere through a ventilation cap (breather). Shaft sealing is carried out by self-tightening cuffs protected by dirt-reflecting rings.

In the main gear of the rear axle, the drive bevel gear 21 (Fig. 3) differs from the similar gear of the intermediate axle in that its hub is shorter and has internal splines for connection with the drive shaft 22 of the main gear of the rear axle.

Tapered roller bearings 18 and 20 are interchangeable with the corresponding intermediate drive axle bearings.

The rear end of the main drive shaft of the rear axle rests on one roller bearing installed in the crankcase bore.

For the circulation of lubricant near the bearing in the neck of the crankcase, a channel is made. From the end, the bearing is closed with a cap.

The rest of the main gear and the cross-axle differential of the intermediate and rear drive axles are similar in design.