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 first required flow rate is calculated as a function of a first maximum allowable flow rate and a value of a first signal. A second required flow rate is calculated as a function of a value of the second signal. When the first maximum allowable flow rate is higher than a first capacity, the value of the first signal is a maximum level, and the value of the second signal is equal to or higher than a minimum level and equal to or lower than a maximum level, a first working fluid supply is controlled to discharge working fluid at a flow rate equal to the first capacity, and a second working fluid supply is controlled to discharge working fluid at a flow rate obtained by deducting the first capacity from the first maximum allowable flow rate, added to the second required flow rate.

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 first required flow rate is calculated as a function of a first maximum allowable flow rate and a value of a first signal. A second required flow rate is calculated as a function of a value of the second signal. When the first maximum allowable flow rate is higher than a first capacity, the value of the first signal is a maximum level, and the value of the second signal is equal to or higher than a minimum level and equal to or lower than a maximum level, a first working fluid supply is controlled to discharge working fluid at a flow rate equal to the first capacity, and a second working fluid supply is controlled to discharge working fluid at a flow rate obtained by deducting the first capacity from the first maximum allowable flow rate, added to the second required flow rate.

An oxygen sensor socket kit provides an air impact driver and at least one slotted socket forming an annulus forming an inside surface with a plurality rectangular flats parallel to and symmetrically arranged around a central axis. The slot is slot formed through the socket sidewall positioned in place of one or a portion of one of the rectangular flats. An outer surface incorporates at least one radially offset protrusion forming a wing body and having a planar striking surface that lies along a radial projection from the central axis on a plane that intersects central axis. A striking surface forms one or more recesses of a concave shape to receive in a rounded tool tip an air impact driver. The driver has an offset distal portion having an angular offset sufficient to allow a direction of an impact force directly laterally offset from a centerline of the output shaft.

An oxygen sensor socket kit provides an air impact driver and at least one slotted socket forming an annulus forming an inside surface with a plurality rectangular flats parallel to and symmetrically arranged around a central axis. The slot is slot formed through the socket sidewall positioned in place of one or a portion of one of the rectangular flats. An outer surface incorporates at least one radially offset protrusion forming a wing body and having a planar striking surface that lies along a radial projection from the central axis on a plane that intersects central axis. A striking surface forms one or more recesses of a concave shape to receive in a rounded tool tip an air impact driver. The driver has an offset distal portion having an angular offset sufficient to allow a direction of an impact force directly laterally offset from a centerline of the output shaft.

A hydraulic hammer for a working machine configured for digging a surface includes a housing, a chisel, sensors, and a controller. The housing is coupled to the working machine. The chisel is partially enclosed by the housing and extendable from the housing for digging the surface at a contact location. Each of the sensors is configured for generating a signal indicative of a projecting distance between one of the sensors and the surface. The controller is configured for receiving the signals, determining an angle between the chisel and a plane substantially tangent to the contact location, and reorienting the chisel so that the chisel is substantially orthogonal to the contact location with the angle at substantially ninety degrees.

A hydraulic hammer for a working machine configured for digging a surface includes a housing, a chisel, sensors, and a controller. The housing is coupled to the working machine. The chisel is partially enclosed by the housing and extendable from the housing for digging the surface at a contact location. Each of the sensors is configured for generating a signal indicative of a projecting distance between one of the sensors and the surface. The controller is configured for receiving the signals, determining an angle between the chisel and a plane substantially tangent to the contact location, and reorienting the chisel so that the chisel is substantially orthogonal to the contact location with the angle at substantially ninety degrees.

A fluid pressure hitting device comprises a piston inserted in a cylinder, a chisel, and a first, second, and third chambers. The chisel is fitted in the cylinder such that a part of the chisel projects from one axial end of the cylinder and is configured to further project from that axial end due to being hit by the piston as the piston slides toward the one axial end. The first through third chambers are partitioned by an inner peripheral surface of the cylinder and an outer peripheral surface of the piston. The first through third chambers are arranged in the axial direction in order fluid the one axial end to another axial end of the cylinder. A flow path is configured to supply fluid from a fluid supply portion when the piston hits the chisel, to the first chamber.

Hammering power of a hydraulic hammering device is improved by shortening a piston stroke, while keeping hammering energy. The device includes a cylinder, a piston slidingly fitted in the cylinder, and a piston front chamber and a piston rear chamber defined between an outer circumferential surface of the piston and an inner circumferential surface of the cylinder and disposed separately from each other at front and rear, respectively, in an axial direction. The device also includes a switching-valve mechanism driving the piston by switching at least one of the piston front or rear chamber into communication with at least one of a high pressure circuit or a low pressure circuit, and an acceleration piston disposed behind the piston and coming in contact with the piston during a retreat stroke of the piston to urge the piston forward in cooperation with braking force by pressurized oil acting on the piston.