Assembly and adjustment of rear axle final drive and differential in K203 chassis

The K203 chassis is the main vehicle chassis for cranes at home and abroad. The chassis is designed with reasonable performance and reliable performance. It is widely used in truck cranes of 16 tons, 20 tons and 25 tons. The main reducer adopts a single-stage deceleration and a double-gauge gear transmission. The drive gear can be used to increase the support stiffness and increase the bearing capacity of the gear. The gear ratio is 6. 666. The gears are straight bevel gears. Since the end of the 1970s, the Daqing Petroleum Administration has used the KATOX TADANO series of truck cranes. Due to its long service life, the drilling work intensity is high and the working environment is harsh. The rear axle final drive of this type of chassis and The differential has a fault of heating and squealing. Most of the disintegration tests show that the main driven gear is seriously worn, the teeth are broken, the tooth surface is pitting and peeling off, the reduction gear bearing is damaged, and the differential gear is broken. We have adopted the method of replacing the main driven gear pair and the bearing to repair and assemble. Not only saves money, but also the quality of the repair is reliable. We have summed up a set of practical and effective assembly adjustment methods in the repair.
The disassembly of the 21 main reducer and the differential is exemplified by the middle bridge (the middle bridge has one more through shaft and one idler than the rear axle). Park the car on the trench and support the final drive and differential assembly with a small hydraulic jack (with small platform). After removing the outer casing fixing bolts, use the top wire to push the final drive assembly out of the axle housing. This process requires lifting the crane back and forth, adjusting the height of the car, and slowly and smoothly taking out the final drive assembly. After cleaning the sludge on the outer casing, it will be further decomposed. ) Remove the fuse, fuse, bearing cap, bearing sleeve and adjusting nut on both sides in turn. Note that the parts removed above should be cleaned in order, and the left and right parts must not be mixed; Put on the anastomotic mark, then remove the differential and driven gear assembly. If there is no groove mark or pitting, the bearing can continue to be used.
Remove the lock nut and flange of the drive pinion and use the top wire to push the drive pinion out together with the inner and outer bearings. When going out to the top, the distance between the two top wires must be balanced, and be careful not to damage the adjusting gasket. If the surface of the removed bearing roller is not pitting or peeling off, the cage can be used continuously. Replace the main driven gear (the basin angle X bearing and other good parts can be cleaned with cleaning agent or kerosene, then dry the components with clean cotton yarn for use, and clean the shell.
3. Assembly of the main reducer and differential 3.1 Assembling the drive gear (angular gear) The inner and outer bearings of the drive gear are placed in the oil to heat up to about 200C, and the small head of the bearing is mounted on the drive gear (be careful not to forget the collar) , lock the circlip. According to our experience, do not install the guide bearing at this time, otherwise it is easy to crash the guide bearing seat, and the guide bearing should be finally assembled from the housing. Then proceed to the next step of installation, be careful not to forget to adjust the gasket, you can first add all the original gasket. Tighten the oil seal fixing bolt with a moment of 12kg.mjfl, then put the flange and tighten the lock nut with a torque of 90kg.m. And 2 adjust the drive gear bearing pre-loaded after the drive gear, to determine the preload of the drive gear bearing, pre-tightening the main driven gear bearing, can increase the support stiffness and improve the smoothness of the gear mesh. However, if the bearing pre-tightening force is too large, the bearing working conditions will be deteriorated, the transmission efficiency will be reduced, and the bearing wear will be accelerated. It will also cause the bearing to overheat and cause damage. If the bearing preload is too small, it will make a sound. The adjustment of the preload of the drive gear bearing adjusts the bearing preload by the tightness of the flange lock nut. To measure the preload of the bearing, a thin cotton rope can be taken, one end is wrapped around the edge of the bearing retaining ring, the other end is attached to the spring balance, and then the spring balance is pulled along the edge of the bearing retaining ring. The spring balance reading reaches the assembly of the 2 differential and the driven gear. 1) The cleaning agent first cleans the differential bracket bearing fitting hole and the bearing outer race. ) Apply Loctite fastening glue around the seat.
Press the differential pinion and the guide bearing into the bracket, tighten the differential case fastening bolt with a torque of 20kg.m, and apply the Loctite thread fastening glue to the bolt to prevent loosening.
The passive teeth (teeth) are placed on the differential housing, and the housing fixing bolts are coated with Loctite thread fastening glue, and then locked with a torque of 45 kg.m.
4Install the passive tooth and differential assembly into the housing, install the bearing cap, bearing sleeve and adjusting nut in order and direction. Be careful not to twist the adjusting nut thread. Damaged thread. For the above components, the fixing bolts can be tightened according to the torque shown in Figure 1.
4. Parameter adjustment 4.1 Measurement and adjustment of the gear gap First, take a small section of soft lead wire, use a steamed bun to form a 6mm thick lead piece, and then use butter to stick to the middle of the tooth of the driven gear (teeth). Then, the active pinion flange is rotated a few times, and the thickness of the lead piece being pressed out can be approximated as the gap of the gear meshing. We think this gap is there. 4mrn is the most suitable. (Standard is 0. 3nmv0.41mm) If the clearance exceeds 0.4mm, screw the adjustment nut behind the passive tooth (the tooth) a few turns, and the passive tooth front adjustment nut should be rotated several times. If the gap is less than. 4mm, the opposite of the above adjustment method.
4.2 Measurement and adjustment of the tooth surface contact condition 2-3 passive teeth are coated with red paint, and then the flange is rotated, and the passive teeth will leave clear meshing marks. If the center of the meshing mark is not at the center of the gear, the corresponding adjustments should be made according to the conditions listed in Table 1.
Finally, it is repeatedly adjusted to the meshing marks as shown, and the gear clearance is also adjusted to 0.4 nn. ​​After the differential assembly is installed, the preload of the bearings at both ends of the differential assembly is determined, and the screwing of the nut is adjusted. Adjust the bearing preload. The method of measurement is also to take a fine cotton rope, one end is wrapped around the edge of the differential case, the other end is attached to the spring balance, and then the spring balance is pulled along the edge of the differential case. The spring balance reading can reach 2.3~i3kg.
Apply Loctite flat rubber to the edge of the final reducer assembly and the axle housing, and tighten the assembly fixing bolts with a torque of 18kg.m. After the above steps, add about 7 liters of cleaning agent to the axle housing (wash away the protective grease and impurities on the surface of the main driven gear), lift the car body, then hang the 2nd gear for 5 minutes; finally release the cleaning Add the gear oil (level: SAE 80W-90APIGL-. Note that the oil quantity must not be increased, otherwise it will easily cause oil leakage, because after the vehicle is running, the main driven gear agitates the gear oil to form oil mist, which makes the bridge The pressure inside the shell rises, and the oil seal is damaged, which causes the gear oil to leak out. S Conclusion Through the above adjustment, the reduction gear pair will reach a better meshing state. Our company has adjusted 12 total rear differentials so far. Cheng, the use effect is better, saving more than 500,000 yuan. Has achieved good economic results.