Automotive Transmission Shaft: Important Components in the Drivetrain-Jiangsu Sitong Cardan Shaft Co.,Ltd
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Automotive Transmission Shaft: Important Components in the Drivetrain

Views:74     Author:Cardan Shaft Manufacturer     Publish Time: 2020-04-29      Origin:Sitong Cardan Shaft Co.,Ltd

The automobile transmission shaft is composed of a shaft tube, a telescopic sleeve and a universal joint. The telescopic sleeve can automatically adjust the change of the distance between the transmission and the drive axle. The universal joint is to ensure the change of the angle between the output shaft of the transmission and the input shaft of the drive axle, and realize the equal angular speed transmission of the two shafts. Generally composed of universal joint cross shaft, cross bearing and flange fork. The transmission shaft universal joint used in the Steyr series of heavy-duty vehicles adopts roller cross shaft bearings, coupled with a short and thick cross shaft, which can transmit larger torque. A butterfly spring is provided on the bearing end surface to compress the roller. A reinforced nylon gasket with spiral grooves is added to the end of the cross shaft to prevent sintering when transmitting power at large angles or torque.


Automotive Transmission Shaft


The car chooses different types of transmission shafts according to different driving forms. Generally speaking, a 4×2 drive car has only one main drive shaft. The 6×4 drive car has an intermediate transmission shaft, a main transmission shaft, and a middle and rear axle transmission shaft. The 6×6 drive car has not only the middle drive shaft, the main drive shaft, and the middle and rear axle drive shafts, but also the front axle drive drive shaft. The intermediate transmission shaft of a long wheelbase vehicle is generally provided with an intermediate support of the transmission shaft. It is composed of support frame, bearing and rubber support.


Important parts of automobile transmission shaft



Important parts of automobile transmission shaft


The universal joint is a key component on the automobile drive shaft. On vehicles with front-engine rear-wheel drive, the universal joint drive shaft is installed between the transmission output shaft and the drive axle main reducer input shaft; while with front-engine front-wheel-drive vehicles, the drive shaft is omitted and the universal joint is installed Between the front axle half-axle and the wheels, which are both responsible for driving and steering. The car is a moving object. In a rear-drive car, the engine, clutch, and transmission are installed on the frame as a whole, and the drive axle is connected to the frame through an elastic suspension. There is a distance between the two and they need to be connected. When the road is running, the road surface will jump, the load change or the installation position difference between the two assemblies will change the angle and distance between the output shaft of the transmission and the input shaft of the main reducer of the drive axle. "Device to solve this problem, so there is a universal joint.

 

On cars with front- and rear-wheel drive (or all-wheel drive) of the engine, due to the suspension deformation of the car during the movement, there is often relative movement between the input shaft of the main reducer of the drive shaft and the output shaft of the transmission (or transfer case). In addition, in order to effectively avoid certain mechanisms or devices (can not achieve linear transmission), there must be a device to achieve the normal transmission of power, so there is a universal joint transmission.

 

The universal joint transmission must have the following characteristics: a. Ensure that the relative position of the connected two shafts can be reliably transmitted when the relative position changes within the expected range; b. Ensure that the connected two shafts can operate evenly. The additional load, vibration and noise due to the angle of the universal joint should be within the allowable range; c. The transmission efficiency is high, the service life is long, the structure is simple, the manufacturing is convenient, and the maintenance is easy.

 

For automobiles, since the output shaft of a cross-shaft universal joint rotates at a different speed relative to the input shaft (with a certain included angle), a double universal joint (or multiple universal joints) must be used for transmission. And the two universal joint forks connected with the transmission shaft are arranged on the same plane, and the angle between the two universal joints is equal. This is very important. The angle of the universal joint should be minimized during design.


Classification of automobile transmission shaft


Classification of automobile transmission shaft



Automobile Transmission shafts can be classified according to their important components-universal joints. According to whether the universal joint has obvious elasticity in the direction of torsion, it can be divided into rigid universal joint transmission shaft and flexible universal joint transmission shaft. The former relies on the hinge connection of parts to transmit power, while the latter relies on elastic parts to transmit power and has a buffering and damping effect.

 

Rigid universal joints can be divided into different speed universal joints (such as cross shaft universal joints), quasi constant speed universal joints (such as double joint universal joints, three pin shaft universal joints) and constant speed Universal joints (such as ball cage universal joints, ball fork universal joints). Constant speed and non-equal speed refer to whether the driven shaft rotates with the driving shaft, whether the rotational angular rates of the two are equal.

 

Of course, the average speeds of the driving shaft and the driven shaft are equal. The angular velocity of the main and driven shafts is still equal when the included angle between the two shafts changes. It is called a constant velocity universal joint or constant angular velocity universal joint. They are mainly used in wheel drive devices such as steering drive axles and disconnected drive axles, and are mainly used for power transmission in cars. When the car is driven by the rear wheels, the cross shaft type universal joint transmission shaft is often used. For some high-end cars, the constant velocity ball head is also used; when the car is driven by the front wheel, the constant velocity universal joint is often used-etc. Speed universal joint is also a kind of transmission shaft, but the title is different.


Common types of automotive transmission shafts


Common types of automotive transmission shafts


Cross shaft rigid universal joint transmission shaft is the most widely used in automobile transmission system and has the longest history. Normally, the transmission shaft generally refers to a cross shaft rigid universal joint transmission shaft. Cross shaft type rigid universal joint is mainly used to transmit the change of angle, generally consists of flange fork, cross shaft with needle bearing assembly, universal joint fork or sliding fork, intermediate connection fork or spline shaft fork, needle roller bearing Composed of axial fixing parts. Flange forks are generally connected to gearboxes, drive axles or other transmission shafts.

 

Flange fork is a fork-shaped part with flanges, generally forged parts of medium carbon steel or medium carbon alloy steel, there are also sand castings made of nodular cast iron and precision castings of medium carbon steel or medium carbon high-quality alloy steel. Flange forks generally have a flat flange, and some have a trapezoidal tooth flange. The cross shaft with needle roller bearing assembly generally includes four needle roller bearings, a cross shaft, and a grease nipple. Needle roller bearings are generally composed of several needle rollers, a bearing bowl, and a multi-edge rubber oil seal (partly with a skeleton).

 

In some needle roller bearings, there is a circular gasket with oil groove, nylon, copper or other materials, mainly used to reduce the axial clearance of the universal joint and improve the quality of the dynamic balance of the drive shaft . The universal joint fork is a fork-shaped part, generally using forged parts of medium carbon steel or medium carbon alloy steel, and also precision casting parts using medium carbon steel. Axial fixing parts of needle roller bearings are generally elastic rings (internal and external clamping type) for holes (or shafts), or bearing pressure plates, lock plates, bolts, etc.

 

Another important part of the transmission shaft is the sliding spline pair, which is composed of internal and external splines (rectangular, involute) and is used to transmit the change in length. The gimbal swing angle of the drive shaft and the maximum expansion and contraction of the sliding spline pair are determined according to the check of the drive shaft run-out during vehicle layout. The transmission shaft tube is generally made of welded steel pipe rolled with low-carbon steel plates. For large-sized shaft tubes, cold drawn seamless tubes are also used.

 

The outer diameter and wall thickness (or inner diameter) of the shaft tube are determined according to the conditions such as the maximum working torque and maximum working speed transmitted by the transmission shaft. The hollow shaft tube has a smaller mass and can transmit larger torque, and has a higher critical speed than a solid shaft with the same outer diameter. Under normal circumstances, the center distance of two universal joints is not greater than 1.5m. When the distance is close, it is generally composed of two universal joints and a sliding spline pair, and there is no shaft tube in the middle. When the distance is long and the length of the transmission shaft exceeds 1.5m, it is often divided into two or three, using three or four universal joints, and the last one has a sliding spline pair, and the rest have intermediate support structures.

 

A typical intermediate support generally consists of a cylindrical ball bearing, a bearing housing, two oil seals, a rubber pad, and a grease nipple. The intermediate transmission shaft is connected to the frame cross member by the intermediate support bracket, and the axis line of the intermediate transmission shaft is required to be perpendicular to the intermediate support plane. It is generally required that the intermediate support of the transmission shaft is arranged on the first-order critical speed node of the transmission shaft system. During use, maintenance is generally required on time. In areas with grease nipples such as universal joints, sliding spline pairs, intermediate supports, etc., the prescribed grease should be regularly filled in accordance with the relevant regulations. There are also maintenance-free drive shafts with grease reserved in the bearings of the universal joint and the intermediate support, which does not require regular grease filling.


Diagnosis and elimination of common failures of automobile transmission shaft



Diagnosis and elimination of common failures of automobile transmission shaft


The damage, wear, deformation and loss of dynamic balance of the drive shaft parts of the car will cause the car to produce abnormal noise and vibration during driving, and in serious cases will cause damage to related parts. When the car is driving, it emits the sound of "Gordon" when it starts or accelerates, and it obviously shows the feeling of loose parts. If it is not the loose drive gear of the drive axle, it is obviously the loose parts of the drive shaft. The loose part is nothing more than a universal joint cross bearing or a steel bowl and flange fork, a splined shaft and a splined sleeve of the telescopic sleeve. Generally speaking, the cross shaft diameter and bearing clearance should not exceed 0.13mm, and the meshing gap between the telescopic spline shaft and spline sleeve should not be greater than 0.3mm. It should be repaired or replaced if the usage limit is exceeded.

 

If a "buzzing" sound occurs in the chassis while the car is running, and the higher the running speed, the louder the sound. This is generally due to the loose wear of the universal joint cross shaft and the bearing, the wear of the intermediate bearing of the transmission shaft, the damage of the intermediate rubber support, or the loosening of the hanger, or the wrong position of the fixed hanger.

 

When the car is under heavy load, especially during driving bumps, it occasionally makes a knocking sound. It should be checked whether the balance axle of the rear axle is displaced and interferes with the drive shaft. If the noise increases with the increase of the vehicle speed during the operation of the car, and it is accompanied by jitter, this is generally due to the loss of balance of the transmission shaft. This vibration is most noticeable in the cab. The unbalance of the dynamic balance of the transmission shaft should be less than 100g.cm.

 

The failure of the dynamic balance of the automobile transmission shaft will lead to the damage of related components. The most common are cracks in the clutch housing and fatigue damage in the middle rubber support.

 

The installation of automobile drive shaft intermediate hanger is very important in maintenance. If the hanger is not installed properly, it will increase the running resistance and noise of the drive shaft, resulting in early damage to the bearing. When reinstalling the hanger, first of all, do not tighten the hanger fixing bolts, support the car drive wheel with a jack from the ground, hang the low speed gear, slowly rotate the drive shaft to automatically align the drive shaft and the hanger, and then fix the hanger Tighten the bolt.





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