Let's analyze the final drives of the excavators
First of all, the engine of the excavator acts as the power source of the whole car, driving the hydraulic main pump and the pilot pump. The general excavator uses the main pump as the variable swash plate type plunger pump, the pilot pump is the gear pump, the main pump and the pilot pump hydraulic pressure. The oil reaches the main control valve through the hydraulic line. At the same time, the pilot pressure oil is connected to the pilot control valve of the excavator cab. The driver controls the hydraulic circuit of the pilot system through the operating handle and the walking pedal to realize the control of the main control valve spool. The hydraulic oil of each circuit output by the main control valve reaches different actuators (cylinder, hydraulic motor) to realize different actions of the excavator. The hydraulic pressure of the traveling system passes through the main control valve and then reaches the excavator left and right travel motors through the central rotary joint. Finally, the hydraulic oil is returned to the hydraulic tank through the return line through the central swivel joint.
In the hydraulic circuit of the entire traveling system of the excavator, the power component (main pump) to the actuator (final drives motors) also has system control, and the pump control system of the main pump can collect the outlet hydraulic oil of the main pump through the central controller. The pressure, after the analysis and calculation, outputs the electric signal, and the angle of the main pump swash plate is changed by the cooperation of the control valve, the pressure reducing valve, the adjusting cylinder and the like, thereby achieving 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 an arm swing operation valve, a boom bucket operation valve and a left and right travel operation valve in the cab. The operation handles are located at different positions, so that the corresponding operation valve outputs are different. The secondary pilot pressure oil controls the opening or position of the main control valve spool, which is reflected in the speed of the walking speed of the excavator walking system and the direction of the walking. https://www.spfinaldrives.com/
The excavator's walking system may be considered as a hydraulic motor. In fact, the unilateral final drives system includes a walking balancing valve, a walking safety valve, a walking speed switching valve, and a walking speed switching cylinder. , travel brake cylinder, throttle valve and travel motor. The control of the walking direction and walking speed of the excavator is realized by the cooperation of the series of control elements and the executing elements.