8 Common Problems in Daily Maintenance of Loaders
Oct 25 , 2021
1. The first gear and reverse gear are normal, and the second gear has no driving force.

First check whether the shifting handle (skid steer loader) is in place, if it is not in place, readjust it. Then check whether the transmission pressure gauge is depressurized in the second gear position. If depressurization, you must check whether there is pressure oil flowing out of the periphery of the 8-shaped end cover of the gearbox. If there is leakage, you can tighten the surrounding bolts. If the above method still fails to eliminate the fault, you must remove the figure-eight end cap and replace the o-shaped sealing ring and paper gasket. If there is no pressure oil overflow at this time, it proves that there is a problem with the second gear member in the gearbox, and the second gear member must be removed. First check whether the external oil seal of the second gear is damaged, then disassemble the components of the second gear, take out 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 oil cylinder falls off. If the guide pin falls 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 driving cannot be performed. For reasons of pressure drop, replace seals or repair or replace parts.

2. Variable speed pressure, boom, bucket and steering are all normal, but the mining wheel loader still cannot move forward or backward

First check whether there is oil shortage in the gearbox and whether the oil inlet pipe is blocked, and then check the gearbox oil pan (electrical motor) and torque converter filter. If you find metal fragments, etc., you can be sure that the parts in the transmission clutch are damaged. If aluminum chips are found in the gearbox oil pan and the torque converter filter, it is certain that the parts inside the torque converter are damaged. At this time, the gearbox and torque converter must be disassembled and inspected, and the damaged parts must be repaired and replaced. Excluding the above reasons, if the car still cannot travel, it can be determined that the bolts around the second gear member in the gearbox have been cut off, or the intermediate shaft output gear has fallen off, and the power cannot be output. Remedy: You can disassemble the 8-shaped end cover of the gearbox, take out the second gear component, and replace the cut bolts. The bolt material is 40Cr, which must be quenched and tempered, and can never be replaced by ordinary bolts.
3. Weak in first gear and reverse gear, slow driving in second gear

First check whether the pressure indicated by the variable speed pressure gauge is normal. If the pressure reaches 108KPa, increase the throttle to check whether the pointer of the pressure gauge is swinging; if it swings violently, it proves that the turbine oil in the gearbox is too dirty or the amount of oil is insufficient. Check the gearbox oil level check plug to see if the turbine oil can flow out . If there is oil flowing out, the fault is caused by the oil is too dirty, the gearbox and filter should be cleaned, and then replaced with new oil; if the amount of oil is normal and the variable speed pressure gauge indicates normal, the fault may be the transmission (conveyor belt) The input secondary gear between the torque converter and the torque converter is broken, so that the power of the secondary gear of the torque converter cannot be output, and only the power of the primary gear can be output. Remedy: Remove the connection between the torque converter and the gearbox, and replace the damaged input secondary gear.

4. The first gear drive is weak, the other gears are normal

First check the pressure of the speedometer to see if there is a drop in pressure at the first gear position. If the pressure is below 98.1KPa, the first gear drive will be weak. The reason for these phenomena is that the first gear piston ring is scratched or worn too much, so that the pressure oil leaks too much, which makes the first gear drive weak; in addition, it may also be caused by the damage of the o-ring seal outside the first gear cylinder. If the failure is caused by the above reasons, the gearbox must be lifted out, and the damaged piston ring and sealing ring must be disassembled and replaced; if the pressure of the transmission pressure gauge is not reduced in the first gear position, it is likely to be a transmission The lever is not adjusted in place, making the first gear drive weak, and the gear shift lever should be re-adjusted to make it reach the specified position.
5. The engine is working normally and the loader cannot walk

First check the oil limit valve of the gearbox and the variable speed pressure gauge. If it is found that there is a lack of variable-speed torque-changing oil, add new oil. However, it is not advisable to add too much, otherwise it will cause the gearbox to heat up, generally until the limit valve comes out of oil. Then check whether the boom can be raised and lowered and whether it can be steered. If the boom can be raised and lowered, it can be steered, but the loader cannot walk. This is caused by the damage of the variable speed pump and lack of oil. The boom cannot be raised, lowered or turned, and the loader cannot travel. This situation is mostly caused by the steel plate connection of the torque converter (meat machine) being sheared by bolts or the elastic plate is broken. The diesel engine and the gearbox must be lifted out together, and then the connecting part of the diesel engine of the torque converter must be removed, the damaged part must be found out, and the damaged part must be replaced or repaired.

6. Can only go forward but not go back

First check whether the pressure indicated by the variable speed pressure gauge is normal. If the reverse gear pressure drops, it proves that there is too much oil leakage in the reverse gear, and the gearbox must be lifted out and all disassembled for inspection. Take out the reverse gear piston, replace the piston ring, check the damage of the friction plate, replace the more worn friction plate, and re-adjust the reverse gear gap to 1.6-2.6mm; if the reverse gear does not reduce the pressure, it proves that the forward gear has Stuck phenomenon. If the reverse gear friction plate slips and the reverse gear cannot travel, the gearbox must be lifted out and disassembled to check whether the isolation ring on the first gear inner gear ring is broken. Because the fragments can jam the friction plate of the first gear, the friction plate of the reverse gear is slipped and does not work, resulting in only forward but not retreat. The isolation ring can be taken out and replaced with a new one to eliminate it.
7. Weak drive and stop at all times

(1) Check the oil limit valve next to the gearbox, and add new oil when there is no oil.

(2) If the oil volume is normal, check the variable speed pressure gauge. If the pressure gauge swings violently, indicating insufficient oil supply, check whether the oil inlet pipe is blocked, whether the inner layer of the hose is foamed due to aging, whether the torque converter filter is clean, and whether the filter element of the filter is clean. If this is the reason, clean and use compressed air (compact loader) to flush the blocked duct and filter element several times until it is unblocked before use. The bubbling hose needs to be replaced.

(3) Observe whether there are metal blocks and aluminum scraps on the filter screen. If there are, it indicates that there are damaged parts in the torque converter and gearbox. It must be disassembled and inspected, and the damaged parts must be replaced.

8. The transmission pressure is normal, neither the first gear nor the reverse gear can travel, only the second gear can drive normally

Most of the reasons for this failure are directly shifting gears without stepping on the brake pedal, twisting the first and reverse gear connecting discs in the gearbox, so that the power cannot be transmitted. The second gear is directly connected to the inner spline of the sun wheel, and the power can be directly transmitted, so the second gear can drive.

Have you encountered these eight small faults in your daily work? Have you used the correct method for maintenance?

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