This percussion apparatus includes a striking piston mounted so as to be displaced inside a piston cylinder and arranged to strike a tool; and a guide bearing comprising a guide surface configured to guide the striking piston during the displacements of the striking piston in the piston cylinder. The guide bearing includes a centering device configured to center the striking piston in the piston cylinder, the centering device comprising centering chambers formed in the guide surface and distributed around the striking piston, each centering chamber being fluidly connected to a high pressure fluid supply circuit; and at least one discharge groove formed in the guide surface of the guide bearing and located proximate to at least one of the centering chambers, the at least one discharge groove being fluidly connected to a low pressure circuit.

This percussion apparatus includes a striking piston mounted so as to be displaced inside a piston cylinder and arranged to strike a tool; and a guide bearing comprising a guide surface configured to guide the striking piston during the displacements of the striking piston in the piston cylinder. The guide bearing includes a centering device configured to center the striking piston in the piston cylinder, the centering device comprising centering chambers formed in the guide surface and distributed around the striking piston, each centering chamber being fluidly connected to a high pressure fluid supply circuit; and at least one discharge groove formed in the guide surface of the guide bearing and located proximate to at least one of the centering chambers, the at least one discharge groove being fluidly connected to a low pressure circuit.

A hydraulic breaking hammer and method of supporting a percussion piston is provided. The breaking hammer includes a percussion device provided with a reciprocating piston. The piston is supported on a frame at its end portions by a first piston bearing element and a second piston bearing element. The second piston bearing element includes a collar sealing element facing towards a working collar of the piston. The piston bearing elements are easily mountable and dismountable separate components.

A hydraulic breaking hammer and method of supporting a percussion piston is provided. The breaking hammer includes a percussion device provided with a reciprocating piston. The piston is supported on a frame at its end portions by a first piston bearing element and a second piston bearing element. The second piston bearing element includes a collar sealing element facing towards a working collar of the piston. The piston bearing elements are easily mountable and dismountable separate components.

A pneumatic tool includes: a drive mechanism which is configured to be driven by compressed air of a first pressure: and a valve mechanism which is configured to be actuated by compressed air of a second pressure, which is higher than an atmospheric pressure and lower than the first pressure, and which is configured to switch whether or not to supply the compressed air of the first pressure to the drive mechanism.

A pneumatic tool includes: a drive mechanism which is configured to be driven by compressed air of a first pressure: and a valve mechanism which is configured to be actuated by compressed air of a second pressure, which is higher than an atmospheric pressure and lower than the first pressure, and which is configured to switch whether or not to supply the compressed air of the first pressure to the drive mechanism.

Provided is a two-piston hydraulic striking device that has stable operativity. This two-piston hydraulic striking device includes two striking mechanisms for striking one transfer member. Each striking mechanism has a pressure receiving area ratio between the front and rear of a piston thereof set in such a way that the two striking mechanisms have the same cycle time.

Provided is a hydraulic striking device in which a reverse operation circuit and a forward operation circuit can switch connection states to a high pressure circuit and a low pressure circuit by means of an operation switching valve. Further, the hydraulic striking device is configured to be selectable between a reverse operation mode or a forward operation mode by operating the operation switching valve. A high/low pressure switching portion is provided with a shortening portion for reducing the time required for high/low pressure switching operation in piston front and rear chambers in association with retraction of a valve to be shorter than the time required for high/low pressure switching operation in the piston front and rear chambers in association with advancement of the valve.

Provided is a hydraulic striking device in which a reverse operation circuit and a forward operation circuit can switch connection states to a high pressure circuit and a low pressure circuit by means of an operation switching valve. Further, the hydraulic striking device is configured to be selectable between a reverse operation mode or a forward operation mode by operating the operation switching valve. A high/low pressure switching portion is provided with a shortening portion for reducing the time required for high/low pressure switching operation in piston front and rear chambers in association with retraction of a valve to be shorter than the time required for high/low pressure switching operation in the piston front and rear chambers in association with advancement of the valve.

A hydraulic striking device that is mounted on construction equipment such as an excavator and breaks solid rocks in the grounds using a rod that is hit by a piston is proposed. Particularly, a hydraulic striking device that can automatically switch stroke modes by sensing the intensity of pressure of an upper chamber formed at an upper portion between a piston and a cylinder in accordance with the statuses of rocks in the ground is proposed.