According to the power source driving the main distribution valve, the basic types of operation control system of hydraulic excavator can be divided into mechanical lever type, hydraulic type, pneumatic type and electrical type. The hydraulic system of the hydraulic excavator has large flow and high pressure, and the driving force of the valve core of the main distribution valve is large. In order to reduce the labor intensity of operators and facilitate reasonable layout, hydraulic, pneumatic and electrical operation control systems are mostly used. This page mainly introduces the mechanical control system.
At present, many hydraulic excavators still use mechanical control system, which has the advantages of simple structure and reliable operation. In the mechanical control system, the bucket, boom, stick and swing joystick of the excavator are connected with the main distribution valve through a lever.
The section from "start oil supply forward" to "start oil supply backward" is the empty stroke of the handle. The size of the empty stroke depends on the assembly clearance of the pin shaft and the stiffness of the lever, that is, when the pin shaft clearance is small and the stiffness is large, the empty stroke is small, otherwise it is large. In order to ensure the timely action of the working device of the excavator, the empty stroke should not be too large.
The section from "start oil supply forward" or "start oil supply backward" to "rated speed" is the acceleration section, and the stroke is generally 20 ~ 40mm. The total movement of the joystick between the front and rear key points shall not exceed 340mm.
In order to reduce the time of changing hands and increase the opportunity of compound action, the traditional four handle control system is improved to double handle control system in current hydraulic excavators.
