In our real life applications, mini skid steer loader are widely used, but it is inevitable that they will fail in use. The mini skid steer loader do not move or cannot move at each gear. The fault range can be limited to the common oil circuits and components of torque converter, traveling pump, pressure reducing valve and other gears. In case of such failure, it can be observed that the main transmission shaft will not rotate when the whole machine is not running.
For such faults, 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 mark on the side of the transmission. If the oil level is not visible, replenish the oil in time. After the oil level is normal, identify whether the fault occurs suddenly or gradually. In case of sudden failure, the pressure reducing valve should be disassembled and inspected to see whether it is dirty, and whether the surface of the valve core is scratched and stuck at the minimum oil supply position. It can be solved by cleaning and grinding, and then check whether the spline of the connecting sleeve of the traveling pump is damaged; If the fault symptom appears slowly, it is generally caused by the gradual wear of the parts of the traveling system or the poor cleanliness of the oil, which can be checked in the following order:
(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 there is a large amount of aluminum dust attached to the filter screen, it can be concluded that the internal bearing of the torque converter is damaged and the "three wheels" are worn. Remove the torque converter, replace the damaged parts and clean the oil circuit.
During operation, the transmission oil in the working oil chamber of the torque converter must be kept full. Insufficient oil will reduce the output torque and make the main transmission shaft weak or stop rotating. During the inspection, disconnect the low pressure hose of the return oil (torque converter overflow) from the torque converter to the transmission, and observe the overflow flow of the return oil pipe under the idle state of the engine. Under normal conditions, there is only a small amount of flow. With the increase of engine speed and the sudden opening of the relief valve in the torque converter pressure reducing valve, the flow will suddenly increase. If the flow rate is also large when the engine is idling, it can be determined that the sealing ring in the torque converter is seriously worn and causes internal leakage.
(2) If the oil return from the torque converter to the gearbox is normal, the engine will run at high speed. If the oil return is small, check whether there is dirt or air leakage in the oil suction pipeline of the traveling pump. Mainly check whether the oil suction filter screen installed in the gearbox and the rubber hose of the walking pump are aged, internally fallen off or bent.
(3) If the above is normal, it can be determined that the volumetric efficiency of the traveling pump is low, then 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.
Drivers who often drive mini skid steer loader will certainly encounter some failures. This article introduces some of the failures and solutions, hoping to bring help to all drivers.