(1) Failure phenomenon
The engine throttle is fully open, and the forklift's inlet oil pressure of the torque converter is less than the standard value at zero speed.
(2) Fault diagnosis and elimination
First pull out the dipstick to see if the torque converter oil level is between the two engraved lines. If the oil level is normal, the inlet and outlet pipes should be checked for leaks, and if there is a leak, it should be eliminated according to the specific situation.
If the inlet and outlet pipes are well sealed, check the operation of the torque converter inlet and outlet pressure valves. If the pressure valve cannot be closed, the pressure valve should be removed to check whether the components are worn, whether the oil path and oil hole are smooth, and whether the spring is permanently deformed. When parts wear exceeds the limit value, it should be replaced or repaired.
If the pressure valve is working properly, the inlet pipe and filter screen should be dismantled and if there is a blockage, the deposit should be removed and cleaned. If the oil pipe is unblocked, the hydraulic pump needs to be repaired and replaced if necessary.
3. Oil leakage
(1) Failure phenomenon
Is manifested by obvious oil leakage marks on the joint surface of the torque converter back cover and the pump wheel and the connection between the pump wheel and the hub.
(2) Fault diagnosis and elimination
If there is oil droplet leakage at the connection between the torque converter and the engine, a piece of white paper can be attached to the process hole window. If the engine throws oil from the connection after the engine is started, it may be the bolt (or connection rivet) at the pump wheel and the pump hub ) Loose, aging seals, loose oil plugs or damaged gaskets. At this time, the bolts (or rivets) should be tightened and the oil leakage should be checked again. If the oil leakage still occurs, the sealing ring should be replaced.
If a large amount of oil leaks from the connection between the torque converter and the engine (oil flowing outwards), the pump wheel cover is cracked. The torque converter should be disassembled and the pump wheel cover replaced.
If the oil leakage part is at the screw plug of the oil filling port or the oil drain port, the tightness of the screw plug should be checked first. If the screw plug is too loose, it should be tightened again; if the screw plug is not loose, the threaded hole should be checked for cracks.
4. Abnormal sound
(1) The fault phenomenon is that when the torque converter is working, the metal friction sound or impact sound is emitted inside.
(2) Fault diagnosis and elimination First check whether the fixing bolts of the torque converter and the engine are reliable. If the fixing bolts are loose, they should be tightened and reach the specified torque; if the fixing bolts are tightened properly, some hydraulic oil should be released from the torque converter Check for impurities in the oil. If the oil is clean and free of metal powder, the bearing should be loose or worn; if the oil released contains aluminum fines, it means that the internal components are abnormally worn.
5. Weak driving
(1) The failure phenomenon is that after the gear is started and the engine speed is increased, the forklift is weak and slow.
(2) Fault diagnosis and elimination First, check whether the indicated pressure of the gear pressure gauge is within the normal range. If the pressure is too low, the second type of fault should be used to find the influencing factors. If the pressure is normal and the driving is weak, the internal seal ring of the torque converter is damaged, the pump wheel is worn out, or the turbine blade is damaged.
Transmission friction clutch failure can also lead to weak driving. At this time, the end cover of the friction clutch can be removed to check whether the seal ring is worn or aging, and whether the end cover has grooves. Replace or repair as appropriate. If the friction clutch is working properly, the torque converter should be disassembled to check the wear of the seal ring, turbine, and pump wheel.
Cannot drive after starting the engine. It may also be that the spool of the torque converter inlet and outlet pressure valve is stuck or the clutch cannot be engaged. The inlet and outlet valves can be removed to see if the spool is stuck. If there is a stuck phenomenon, it should be cleaned to make it move freely. If necessary, the hydraulic oil should be replaced. If the spool is good, the clutch may be "locked". If the gear cannot be engaged, the clutch should be disassembled to eliminate the fault.
