In our practical application, small loaders are widely used, but they will inevitably fail in use. Each gear of the small loader can not walk or walk, and the fault range can be limited to the torque converter, travel pump, pressure reducing valve and other common oil circuits and components. When this kind of fault occurs, we can observe that the main drive shaft will not rotate when the whole machine is not running.
For this fault, first check whether the hydraulic oil in the transmission is sufficient. The method is to keep the engine at idle speed. Observe that the oil level should be in the middle of the oil pointer on the side of the transmission. If the oil level is not visible, replenish the oil in time. After the oil level is normal, judge whether the fault occurs suddenly or gradually. In case of sudden failure, the pressure reducing valve should be removed to see if there is dirt and if the surface of the valve core is scratched and stuck in the small oil supply position. Before checking whether the spline of the connecting sleeve of the traveling pump is damaged, it can be solved by cleaning and grinding. If the fault signs appear slowly, it is generally due to the gradual wear of the traveling parts or the poor cleanliness of the oil.
(1) Determine whether the fault is in the torque converter. Check the mechanical oil return filter installed on the rear frame of the vehicle. If a large amount of aluminum dust is attached to the filter screen, it can be judged that the "three wheels" wear is caused by the damage of the bearing in the torque converter. The torque converter should be removed, the damaged parts should be replaced, and the oil circuit should be cleaned.
During operation, the transmission oil in the working oil chamber of the torque converter must be full. Insufficient oil will reduce the output torque and make the main transmission shaft unable to rotate or stop rotating. During the inspection, separate the low pressure hose of the return oil (torque converter overflow) from the torque converter to the transmission and observe the overflow of the return oil pipe when the engine is idling. Normally, there is only a small amount of flow. With the increase of engine speed, the flow will suddenly increase when the relief valve in the torque converter pressure reducing valve suddenly opens. If the flow rate is large when the engine is idling, it can be judged that the sealing ring in the torque converter is seriously worn, resulting in internal leakage.
(2) If the torque converter returns to the transmission normally, the engine will run at high speed. If the oil return is small, check whether the oil suction pipe of the traveling pump is blocked by dirt or leaks. Mainly check whether the oil suction screen and the traveling pump hose installed in the gearbox are aging, falling off or bending.
If the above normal conditions indicate that the volumetric efficiency of the traveling pump is low, replace the traveling pump.
(4) Generally, the failure of torque converter oil return and heat dissipation circuit is not considered for the failure of weak travel.
