1. Composition and function of the drive axle
The drive axle is composed of the main reducer, differential, half shaft, and drive axle housing. Its function is to transmit the engine torque transmitted by the universal transmission device to the driving wheels, achieving reduced speed and increased torque.
1.1 The function of the main reducer
The main reducer is used on three wheel and a small number of small tonnage four wheel agricultural vehicles. Due to the use of a transverse horizontal diesel engine, the rotation axis direction of the gears in the transmission system is consistent with the rotation axis direction of the vehicle's driving wheels. Therefore, the main reducer is a pair of cylindrical gears, which only serves to reduce the speed and increase the torque. However, for agricultural vehicles equipped with vertical diesel engines, due to the 90 ° angle between the rotation axis direction of the gears in the transmission system and the rotation axis direction of the vehicle's driving wheels, the main reducer adopts a bevel gear transmission, which not only takes off and reduces speed, increases torque, but also changes the rotation direction of the gears by 90°.
1.2 The function of the differential
Realize different rotational speeds of the left and right half axles and wheels. Especially when turning agricultural vehicles, achieve fast outer wheel speed and slow inner wheel speed to achieve smooth turning and reduce tire wear.
1.3 The function of the half axis
The function of the half axle is to connect the half axle gear of the differential with the driving wheel. At present, the half axles of three wheel and four wheel agricultural vehicles are mainly divided into semi floating and fully floating half axles based on their structure and layout. On a large number of three wheeled agricultural vehicles and small tonnage four wheeled agricultural vehicles, the half axle is generally semi floating, but on large tonnage agricultural vehicles, the half axle is generally fully floating.
2. Precautions for maintenance of drive axle
2.1 The driving axle of agricultural vehicles adopts a semi floating support form, which has a simple structure and is mainly used in vehicles with small reaction and bending moments. This structure can only prevent the inner end of the half shaft from bending moment, while the outer end bears all bending moments. The outer end of the half shaft is supported by a radial ball bearing and connected to the inner spline on the brake drum by the outer spline. It is locked together by a flat washer, spring washer, and groove nut, with a tightening torque of 12.7-17.6 N · m, and then locked with a cotter pin.
If there are quality issues with components due to improper installation and adjustment, as well as frequent bumps on harsh road surfaces, it can cause early wear of the spline pair and radial ball bearings that fit the outer end of the half shaft with the brake drum. This should be noted by users and maintenance personnel.
2.2 Most agricultural transport vehicles adopt the structure of front engine transverse front drive, so the drive shaft is a disconnected type, which is divided into left and right drive shafts. Both ends of each drive shaft are connected to the differential and hub respectively by constant velocity universal joint. The advantages are simple structure, light weight, good heat dissipation, large load-bearing capacity, reliable operation, and easy layout. The disadvantage is that the machining accuracy requirements are high and the process is complex. During maintenance, special attention should be paid to the following points:
(1) Is the drive shaft deformed.
(2) Whether the constant velocity universal joint has abnormal wear or damage.
(3) Is there any abnormal wear or damage to the spline parts and bearings.
2.3 When the agricultural vehicle has driven for a certain distance, the rear axle, also known as the rear axle hub, becomes hot and hot, making it difficult to rotate. The following inspection, adjustment, or maintenance should be carried out: first, extract the half axle, set up the wheels, and conduct a test run. If the wheels rotate with difficulty, it indicates that the bearing assembly is too tight and should be adjusted accordingly. If the wheels do not rotate vigorously, it is generally due to lubrication issues, causing the rear axle to heat up. At this time, lubrication and maintenance should be carried out.
3. Disassembly and precautions of the drive axle
3.1 Disassembly of the drive axle assembly
Drain the lubricating oil, remove the 12 half shaft fastening nuts, and use two M12 screws × A 35mm bolt is screwed into the screw hole on the half shaft flange to push out the half shaft.
Disconnect the transmission shaft from the rear axle, disconnect the rear brake hose from the joint, remove the 12 bolts connecting the reducer housing to the rear axle housing, and remove the reducer and differential assembly from the rear axle housing.
3.2 Disassembly of the reducer and differential assembly
(1) Mark the left and right bearing covers of the differential to restore their original working condition. Release the differential bearing cover nut lock, remove the nut, and remove the bearing cover. Take out the reducer assembly.
(2) Remove the connecting bolts between the driving bevel gear bearing seat and the reducer housing, and do not lose or damage the adjusting gasket of the driving bevel gear bearing seat when removing the bearing seat.
(3) Remove the fastening bolts and side cover of the reducer side cover, and check if the outer ring of the bearing is damaged. If it is not damaged, it does not need to be removed.
(4) Take out the driving cylindrical gear and driven bevel gear assembly, check if the bearings are damaged, and if not, do not replace them. Mark the left and right covers and adjusting washers separately for easy assembly installation.
3.3 Disassembly of the driving bevel gear assembly
Remove the cotter pin and nut that fasten the flange of the driving bevel gear. Use a special tool to press out the driving bevel gear and rear bearing inner race assembly, remove the flange, loosen the bearing cover bolts, and remove the bearing cover and oil seal assembly.
3.4 Disassembly of differential assembly
Check the differential assembly. If the bearings are intact, the inner race assembly of the bearings does not need to be removed from the differential housing. Remove the split pin and loosen the bolts used to fasten the differential housing and the driven cylindrical gear. Gently tap the outer edge of the driven cylindrical gear with a copper hammer to disassemble the reducer.
Attention: Before disassembly, marks should be made on the corresponding positions of the left and right shells of the differential and the driven cylindrical gear for installation in place.
3.5 Installation precautions
During installation, it is important to correctly identify gears with different gear ratios. For an overall drive axle or reducer, it is not possible to directly calculate the number of teeth for each gear, and thus the speed ratio of the drive axle cannot be calculated. For easy identification, four letters A, B, C, and D are cast on the front bearing cover of the driving bevel gear in the design, and a short line is also cast for each letter. These four letters represent several speed ratios, respectively. When assembling a reducer, cut a gap in the horizontal line below the letter indicating the speed ratio of the reducer, thus removing it from the outer surface of the reducer? It's easy to know the speed ratio.
More about VAFEM Shock absorber bearings：
Shock absorber bushings come in common forms – rubber and metal. Rubber bushings are at the top and bottom of the shock absorber and are used to attach the shock to the vehicle’s frame and control arm. These bushings are sometimes spherical plain bearings or rod ends in a rubber housing.
As a precious high quality shock absorber bearings manufacturer and supplier in China, VAFEM can guarantee the quality and precision of the products through complete testing technology and advanced equipment. Please come to buy shock absorber bearings at the best price and quality from VAFEM. Please contact us for any questions!
2023-05-26