(1) The pressure holding circuit of the accumulator is used. The feed oil circuit and clamping oil circuit function as an oil pump. When the feed hydraulic cylinder moves quickly, the pressure of the clamping cylinder must not drop, that is, the workpiece is clamped. When the clamping cylinder moves quickly, the pressure of the oil pump drops, and the one-way valve closes due to the pressure of the clamping cylinder, separating the feed oil path from the clamping oil path, and the accumulator is used to supplement leakage to maintain the pressure of the clamping cylinder.
(2) The pressure holding circuit using the hydraulic control check valve of the waste paper baler and the electric contact pressure gauge. When the pressure in the upper chamber of the cylinder drops to the setting value of the lower contact of the electric contact pressure gauge due to leakage or other reasons. The electrical contact pressure gauge sends a signal, the valve is in the right position, and the pump supplies oil to the upper cavity of the cylinder. When the pressure rises to the set pressure of the contact on the electrical contact pressure gauge, the electrical contact pressure gauge sends a signal again , So that the valve is in the neutral position. The pressure in the upper chamber of the cylinder is maintained by the hydraulically controlled check valve 7, and the pump is unloaded through the middle position of the M-type valve.