Some Information about Wheel Loader Hydraulic System

Wheeled loader is a common machine in engineering construction. It can greatly improve production efficiency and is very convenient to use. But its hydraulic system is easy to break down in work. Based on many years of practical experience, the following introduction about this system is made. 

The working principle of the hydraulic system of wheeled loader is that the whole working device is articulated on the frame of loader and operated by hydraulic pressure. Working Principle: The loader enters the shovel loading position and inserts the bucket into the material. The extension of the rotary bucket cylinder drives the rocker arm to turn over. At the same time, the rocker arm exerts pulling force on the bucket through the connecting rod to make the bucket turn over and shovel the material. After the shoveling material is finished, the rotary bucket cylinder is locked, the bucket position is kept still, the arm cylinder is extended, the arm is raised to one-position position, and the arm lifts the bucket to transportation height. Then the loader transports the material to the unloading place, the moving arm cylinder extends, and the moving arm lifts the bucket to the unloading height. Then the bucket cylinder shrinks, the bucket is pushed by the connecting rod, and the material is dumped forward. At the same time, the boom cylinder is locked and the boom position is maintained. After discharging, the hydraulic cylinder of the boom shrinks, the boom drops to the lowest position, and the bucket is automatically leveled to the excavation state under the action of the automatic leveling device of the bucket. 

Common faults and reasons are that the bucket powerless arm works normally. The reason is that if the bucket of loader is powerless, it is easy to turn around and the arm works normally, it means that the fault is not in the working hydraulic gear pump, but in the bucket cylinder and its control valve. The reason is that the oil seal on the piston of the boom cylinder is damaged and the geometric dimension of the inner chamber of the cylinder is beyond the limit. The excessive clearance or groove of the control valve of the boom cylinder causes the serious pressure of internal leakage to fall short of the prescribed value. The lifting of the boom is weak, and the bucket is weak, because the hydraulic oil pressure pumped by the hydraulic gear pump which supplies the two works is insufficient. 

 The high oil temperature in the hydraulic system of loader is mainly caused by the power loss of the system itself. The heat source mainly comes from power loss of power system (pump), leakage of actuator (hydraulic motor, hydraulic cylinder) along pipeline, partial pressure loss and pressure loss of hydraulic valve. The reason for the high temperature of hydraulic oil is that the heat dissipation capacity of hydraulic oil radiator is far from the design power. Because of the arrangement of the radiator, the hydraulic oil flow through the radiator is small, resulting in the low heat dissipation capacity of the hydraulic oil radiator, and overheating of the system.