I. Gearbox Usage and Maintenance Precautions
1. Before each gear shift, the main clutch should be completely disengaged, and the throttle should be appropriately controlled to avoid gear impact during gear engagement.
2. When shifting to high gear, the gear lever should not be operated with excessive force, otherwise it may damage the shift fork or break the shift shaft travel limit plate, resulting in gear misalignment.
3. The oil seal prevents gearbox gear oil from flowing into the clutch chamber. Therefore, the oil seal should be checked regularly for failure. If there is serious leakage, it should be replaced promptly.
4. Regularly check for oil leakage at the cotter pin. If oil leakage is found, check if the oil seal is faulty.
5. The gearbox and rear axle are connected and use the same gear oil. Lubricating oil is injected through the filler plug hole on the rear upper cover of the rear axle housing. The vent hole on the filler plug should always be kept clear. The oil level can be measured with the dipstick on the right side of the rear axle housing; the oil level should be between the two marks on the dipstick. To drain the oil, unscrew the gearbox drain plug and the rear axle drain plug to drain the oil completely. 6. A clearance adjustment washer is installed on the end face of the power drive shaft to ensure that the clearance at this point is approximately 0.3 mm. If severely worn, it should be replaced during disassembly and repair.
II. Troubleshooting Common Gearbox Faults
1. Knocking Sound from the Gearbox
When a gearbox has been used for an extended period, the internal shafts and bearings experience significant wear, and the gear surfaces also wear accordingly. This leads to uneven meshing of the gear pairs, resulting in a periodic knocking sound. Wear on the planetary gears and shafts in the planetary reduction mechanism can also produce a knocking sound. In this case, the gearbox should be disassembled to identify the cause and replace any damaged parts.
2. Gear Skipping
Frequent gear skipping is mainly caused by malfunctions in the gearbox locking and operating mechanisms. Wear on the upper annular locating groove of the shift fork shaft and insufficient locking spring force can both cause the locking mechanism to fail. In this case, the damaged parts should be replaced. Severe wear or bending of the shift fork, as well as severe wear on the ball joint at the lower end of the shift lever, can affect the shift stroke, causing inaccurate meshing of the working gear pairs and resulting in gear skipping. Damaged parts should be corrected, repaired by welding, or replaced.
3. Gear Shifting Errors
Excessive force when shifting gears can cause the shift shaft travel limiter to bend or break, resulting in gear shifting errors. In this case, the hydraulic lift cover should be removed, the shift shaft travel limiter replaced, and all shift fork shafts and shift forks inspected for damage or bending.
