Firstly, as the power source of the whole vehicle, the engine of the excavator drives the main hydraulic pump and pilot pump. Generally, the main pump is a variable swashplate plunger pump, and the pilot pump is a gear pump. The hydraulic oil of the main pump and pilot pump reaches the main control valve through the hydraulic pipeline. At the same time, the pilot pressure oil is connected to the pilot control valve in the cab of the excavator, The driver controls the hydraulic circuit of the pilot system through the operating handle and walking pedal to control the valve core of the main control valve. The hydraulic oil of each circuit output by the main control valve reaches different actuating elements, such as oil cylinder and hydraulic motor. Realize different actions of the excavator. The hydraulic pressure of the traveling system is output through the main control valve and reaches the left and right traveling motors of the excavator through the central swivel. Finally, the hydraulic oil returns to the hydraulic oil tank through the return pipeline and the central swivel.
In the hydraulic circuit of the whole traveling system of the excavator, the traveling hydraulic motor from the main pump of the power element to the actuator also has systematic control. The pump control system of the main pump can collect the outlet hydraulic oil pressure of the main pump through the central controller, output the electrical signal after analysis and calculation, and change the swashplate angle of the main pump with the cooperation of control valve, pressure reducing valve, regulating cylinder and other elements, So as to achieve the purpose of adjusting the displacement and output flow of the main pump.
The pilot control valve of the excavator is essentially a proportional control valve, which is the stick swing operation valve, Boom Bucket operation valve and left and right travel operation valve in the cab. The operation handle is located in different positions, which can make the corresponding operation valve output different secondary pilot pressure oil and control the opening or position of the valve core of the main control valve, Reflected in the excavator walking system is the speed of walking and the switching of walking direction.
The walking system of the excavator may be thought to be just a hydraulic motor, but it is not. Taking the unilateral traveling system as an example, the traveling system of the excavator includes traveling balance valve, traveling safety valve, traveling speed switching valve, traveling speed switching oil cylinder, traveling brake oil cylinder, throttle valve and traveling motor. Through the mutual cooperation of a series of control elements and actuators, the walking direction and speed of the excavator are controlled.
