Common Fault Causes and Handling Methods of Loaders (1)

Key points for judgment:
When unable to walk or walking slowly, the main transmission shaft rotates quickly and forcefully. When increasing the engine speed, the increase in the main transmission shaft speed is significantly disproportionate to the front and rear transmission shafts.
The transmission oil pressure in neutral and its remaining gears is normal, but the pressure decreases significantly after shifting to this gear.
Fault cause:
1) The bearing cover or nylon ring is severely worn.
2) If the bearing cover or nylon ring is in good condition or slightly worn, it is confirmed that the inner and outer sealing rings of the clutch are poorly sealed.
Exclusion method:
Replace the corresponding damaged parts, such as the bearing cover or nylon ring, inner and outer sealing rings, and readjust the gap between the shaft sleeve and the bearing cover.
Fault analysis:
If a certain gear is unable to move or cannot move, problems with the common oil circuits and components of the torque converter, travel pump, pressure reducing valve, and other gears can be ruled out. The fault can only occur in the oil circuit between the transmission control valve and the clutch piston of that gear.
After the wear of weak components such as bearing covers, nylon rings, and inner and outer sealing rings, a large amount of oil supplied to the clutch piston chamber leaks from the worn area, resulting in a decrease in oil pressure.
When shifting to neutral or other gears, the oil pressure display is normal because the fluid does not flow through the worn area.
2、 The machine automatically moves forward in neutral, and can also travel normally when shifting into forward gear. When shifting into reverse gear, the machine stops and cannot move. The working pressure of each gear is normal.
Fault cause:
Sintering and locking of the main and driven plates of the forward clutch
Forward clutch piston stuck, support check valve blocked
Exclusion method:
Disassemble the forward clutch, clean the oil passage, replace the main and driven friction plates and related damaged components, clean all related parts, replace the outer sealing ring, clean and unblock the one-way valve, replace the clutch friction plate, inner and outer sealing rings.
3、 During normal driving of the entire machine, it suddenly stops working after shifting to second gear. Check that the working pressure of this gear and other gears is normal.
Fault cause:
The clutch shaft of this gear is broken
Exclusion method:
Replace the clutch shaft and readjust the bearing clearance
4、 The entire machine suddenly stops moving forward or backward while driving, and the working pressure of the transmission is normal.
Fault cause:
1) Failure of the variable speed distribution valve or damage to the accumulator (40F, 50D, 50F). The pneumatic control valve stem of the variable speed valve is stuck or damaged
2) Blocked oil inlet
3) Accumulator oil circuit blocked
4) Pneumatic stop valve failure
Exclusion method:
Clean the isolation valve stem of the variable speed valve or replace the pneumatic control valve to clear all relevant oil circuits, repair or replace the pneumatic stop valve
5、 If the entire machine is working normally and suddenly does not lift or move without turning, it is due to damage to the elastic connecting plate or teeth on the connecting wheel
Fault cause:
The elastic connecting plate is broken, the fixing bolts of the elastic connecting plate are damaged, and the connecting wheel is toothed
Exclusion method:
Replace the elastic connecting plate and the connecting wheel