Abstract: In order to study the pump control system of DA valve in detail, ensure the flexibility of DA control system in application of engineering machinery, and guarantee the best working state of the equipment in different working conditions, the structural principle and test curve of DA valve and DA pump are analyzed. The main functions of DA pump are demonstrated as follows: (1) The function of displacement control by engine speed, i.e. the automatic driving function can change the pump displacement by manipulating the engine accelerator pedal, thus changes the speed. (2) Then function of power constant, i.e. the stable power output of pump can be guaranteed by adjusting and locking the pump setting to adapt to the prime mover power. (3) The function of pressure cutoff, i.e. the pump displacement is closed to zero when the pump pressure reaches the set maximum limit pressure to prevent the engine from flaking out due to overload. Through the setting and debugging of main parameters of hydraulic system of specific equipment, the debugging method and process of DA pump system are given, so as to achieve the best match between DA pump torque and engine torque, reduce the engine power loss, prevent the engine from flaking out due to overload, and reduce the fatigue and burden of operators.

Key words: DA valve, DA pump, control pressure, displacement