Fault Analysis and Elimination Methods for the Hydraulic Transmission System of Loaders

During the operation of loaders, their working efficiency is often affected by faults in the transmission system. The following are some typical faults of the transmission system of loaders and their troubleshooting methods, for the reference of colleagues.

The first gear and reverse gear are normal, but the second gear has no driving force

First, check if the gearshift handle is in place. If not, readjust it. Then check whether the pressure gauge at the second gear position has dropped. If it has, it is necessary to check whether there is pressure oil flowing out from the periphery of the figure-eight end cover of the transmission. If there is any leakage, the bolts around can be tightened. If the above methods still cannot eliminate the fault, the 8-shaped end cover must be removed and the O-ring and paper gasket replaced. If no pressure oil overflows at this point, it indicates that there is a problem with the second gear component inside the transmission, and the second gear component must be removed. First, check whether the external oil seal of the second gear is damaged. Then, disassemble the second gear component, remove the piston, and check whether the piston ring, oil seal ring and friction plate are damaged. Finally, check whether the guide pin in the second gear cylinder has fallen off. If the guide pin has fallen off, a large amount of pressure oil in the second gear will flow out from here, causing the pressure in the second gear to drop and making it impossible to drive. For the cause of the pressure drop, replace the sealing parts or repair and replace the components.

The variable pressure, boom, bucket and steering are all normal, but the loader still cannot move forward or backward

First, check if there is a lack of oil in the transmission and if the oil inlet pipe is blocked. Then, inspect the transmission oil pan and the torque converter filter. If metal fragments or other objects are found, it can be confirmed that there is damage to the parts inside the large overrunning clutch in the transmission. If aluminum shavings are found in the transmission oil pan and the torque converter filter, it can be confirmed that the parts inside the torque converter are damaged. At this point, it is necessary to disassemble and inspect the transmission and torque converter, and carry out repairs and replace the damaged parts. After ruling out the above reasons, if the vehicle still cannot move, it can be determined that the bolts around the second gear component inside the transmission have been cut off, or the output gear of the intermediate shaft has fallen off, causing the power to be unable to be output. Troubleshooting method: You can remove the 8-shaped end cover of the transmission, take out the second gear component, and replace the cut bolt. This bolt is made of 40Cr material and must undergo quenching and tempering treatment. It can never be replaced by ordinary bolts.

The first gear and reverse gear are weak, and the second gear drives slowly

First, check whether the pressure indicated by the variable speed pressure gauge is normal. If the pressure reaches 108KPa, increase the throttle and check if the pointer of the pressure gauge is swinging. If it swings violently, it indicates that the turbine oil in the transmission is too dirty or insufficient. You should check whether the turbine oil can flow out of the transmission oil level check plug. If there is oil flowing out, the fault is caused by the oil being too dirty. The transmission and filter should be cleaned and then new oil should be replaced. If the oil level is normal and the variable speed pressure gauge indicates normally, the fault might be that the input secondary gear between the transmission and the torque converter is broken, causing the power of the secondary gear of the torque converter to be unable to be output, while only the power of the first gear can be output. Troubleshooting method: Remove the connection between the torque converter and the transmission, and replace the damaged input secondary gear.

The first gear is weak in driving, while the other gears are normal

First, check the pressure of the gearshift gauge to see if there is a pressure drop at the first gear position. If the pressure is below 98.1KPa, the first gear drive will inevitably be weak. What causes these phenomena? Excessive exposure causes the first gear drive to be weak. In addition, it might also be due to the damage of the O-ring on the outside of the first-gear cylinder, causing a large amount of pressure oil to leak. If the malfunction is caused by the above reasons, the gearbox must be lifted out, and the damaged piston rings and sealing rings must be disassembled and replaced. If the variable-speed pressure gauge does not reduce pressure at the first gear position, it is very likely that the variable-speed pull rod has not been adjusted properly, causing the first gear drive to be weak. The variable-speed pull rod should be readjusted to reach the specified position.

The engine is working properly, but the loader cannot move

First, check the oil level limit valve and the speed gauge of the transmission. If it is found that the variable speed and torque oil is lacking, new oil should be added. However, it is not advisable to add too much, otherwise it will cause the transmission box to overheat. Generally, add until oil flows out of the limit valve. Then check whether the boom can rise and fall and whether it can turn. If the boom can rise and fall and also turn, but the loader cannot move, this is caused by the damage and lack of oil in the variable speed pump. The boom cannot rise or fall or turn, and the loader cannot move. This situation is mostly caused by the steel plate connection of the torque converter being cut off by bolts or the elastic plate breaking. The diesel engine and the transmission must be lifted out together. Then, the connection part of the diesel engine with the torque converter should be removed to identify the damaged area and replace or repair the damaged parts.