| 摘要 |
A hydraulic percussion apparatus comprising a body, a cylinder in the body and a percussion piston reciprocating in the cylinder. A distributing valve moves in a valve housing. A valve for starting and stopping the percussion apparatus is provided. A hydraulic pump and hydraulic channels form a percussion circuit with a gas/liquid pressure accumulator. A distributing valve circuit and a free circulation circuit are provided for the pump which are parallelly coupled with the percussion circuit, which circuits are connected to the pump and to the start-and-stop valve which has positions for controlling pressure in the circuits. The start-and-stop valve has a middle position during which pressure in the percussion circuit rises up to a predetermined value while the distributing valve circuit remains closed independent of the pressure in the percussion circuit. |
