How to do when the backhoe loader can't walk suddenly?    

A CASE580M type backhoe loader suddenly appeared a fault that could not walk during its operation. Through the preliminary detection and analysis, the fault is determined from the transmission system.

The transmission line of the equipment is: engine torque converter - transmission (variable speed pump) - transmission shaft - drive axle.

First try to understand the working principle: after the engine power transmission torque converter to variable speed pump, variable speed pump after the oil pressure through the control valve to the transmission in the forward and reverse gear clutch, and then through the different coupling and separation, the successful implementation of the power cut and change direction; through mechanical shifting device inside the transmission can realize the power transfer and cut off. If the machine cannot walk, check torque converter, variable speed control device and transmission variable speed pump.

After checking, the torque converter hydraulic oil quantity is normal, no impurities, oil filter is not blocked, can eliminate torque converter failure.

Check the speed change pump again. (because there is no pressure gauge on the machine, it can only be judged by experience). There is a pressure measuring plug in the transmission valve body, loosen the screw, start the engine oil and a spill from the mouth of the measurement; unloading pressure measuring plug, no oil spray, the fault may be in gear pump.

Therefore, the speed change pump is disassembled and found that the driving gear of the drive gear has been interrupted, causing the speed change pump not pumping oil, so that the forward and backward clutch can not work, because the power can not be transmitted, the backhoe loader can not walk.

After welding, filing and reassembled after starting the engine in case of tightening pressure measuring plug, oil spill has been found, in the process of liquid spillage and loose plug in gradually increasing until the screw was sprayed, the judgment of variable speed pump has been restored to normal work, but try to find the machine machine can not back forward, and suspected the problem in the control link.

Check the speed change control device, use the multimeter to detect the switch, wire and solenoid valve, all normal. Finally, the speed change valve is disassembled, and when the solenoid valve is taken off, it is found that the valve stem of the speed change valve has been bent, which makes the valve core unable to make normal reciprocating motion, leading to the obstruction of the forward baffle. After adjusting the valve stem and loading, the backhoe loader has returned to normal.

The maintenance after, as the fault maintenance personnel must have the patience to find fault source equipment, must not be confused.

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