A hydraulic hammering device that uses a scheme in which a front chamber is switched into communication with a low-pressure circuit when a piston advances, wherein occurrences of galling to the piston at a sliding contact portion with a front-chamber liner is reduced. The front chamber has the front-chamber liner fitted to an inner surface of a cylinder. A hydraulic chamber space communicating with the front chamber and filled with hydraulic oil is formed as a cushion chamber on the inner peripheral surface of a rear portion of the front-chamber liner. The cushion chamber has a second drain circuit (from first end face grooves to slits to second end face grooves), which is provided separately from a drain circuit that guides the hydraulic fluid passing through a liner bearing of the front-chamber liner to the low-pressure circuit.

A hydraulic hammer is provided. The hydraulic hammer includes a fluid inlet configured to receive a pressurized fluid for running the hydraulic hammer and a fluid outlet for discharging hydraulic fluid from the hydraulic hammer. A bypass passage fluidly connects the fluid inlet and the fluid outlet, the bypass passage has a bypass inlet fluidly connected to the fluid inlet and a bypass outlet fluidly connected to the fluid outlet. An automatic shut-off valve is disposed in the bypass passage between the bypass inlet and the bypass outlet and is configured to open or close the bypass passage. The automatic shut-off valve is configured to open the bypass passage under pressure of the pressurized fluid on continuous running of the hydraulic hammer for a set time to stop the hammer.

A hydraulic hammer is provided. The hydraulic hammer includes a fluid inlet configured to receive a pressurized fluid for running the hydraulic hammer and a fluid outlet for discharging hydraulic fluid from the hydraulic hammer. A bypass passage fluidly connects the fluid inlet and the fluid outlet, the bypass passage has a bypass inlet fluidly connected to the fluid inlet and a bypass outlet fluidly connected to the fluid outlet. An automatic shut-off valve is disposed in the bypass passage between the bypass inlet and the bypass outlet and is configured to open or close the bypass passage. The automatic shut-off valve is configured to open the bypass passage under pressure of the pressurized fluid on continuous running of the hydraulic hammer for a set time to stop the hammer.

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.

In the case of an incorrect polarity of connectors in hydraulic networks, a switching device is provided, and formed with a connector part, a valve body, a switching part displaced axially in the valve body within limits, a base part and a top part. Wherein cooperating annular chambers for the conducting of a working fluid are formed in the region of an inner surface of the valve body and an outer surface of the switching part. Annular surfaces (A2, A3, A5, A7) are acted upon with pressurized fluid on the switching part towards the top part and annular surfaces (A1, A4, A6) of the switching part are acted upon towards the base part have a following size relations when there is a permanent fluidic connection of the annular chambers:
A2=A3>0.5?A1;
A4>A5+A7;
A3+A7>A4+A6;
A1=2A2?A4+A5?A6+A7.

Provided is a hydraulic hammering device having improved hammering efficiency and of low cost. A piston has a valve switching groove between large-diameter sections thereof. A cylinder has three control ports at positions corresponding to the valve switching groove. A switching valve mechanism has a valve presser for always pressing a valve in one direction and also has a valve controller for moving, when supplying pressurized oil, the valve in the opposite direction against the pressing force of the valve presser. A valve control port communicates with the valve controller so as to supply the pressurized oil to the valve controller and is separated from a piston front chamber and a piston rear chamber. Only either a piston retraction control port or a piston advance control port communicates with the valve control port depending on advance or retraction of the valve switching groove.

Provided is a hydraulic hammering device having improved hammering efficiency and of low cost. A piston has a valve switching groove between large-diameter sections thereof. A cylinder has three control ports at positions corresponding to the valve switching groove. A switching valve mechanism has a valve presser for always pressing a valve in one direction and also has a valve controller for moving, when supplying pressurized oil, the valve in the opposite direction against the pressing force of the valve presser. A valve control port communicates with the valve controller so as to supply the pressurized oil to the valve controller and is separated from a piston front chamber and a piston rear chamber. Only either a piston retraction control port or a piston advance control port communicates with the valve control port depending on advance or retraction of the valve switching groove.

A breaking device includes a frame, an impact device having a pressure chamber with a rear pressure chamber and a front pressure chamber. The breaking device further includes a first low pressure port at the rear pressure chamber, a first low pressure channel and a first low pressure accumulator connected to the first low pressure channel. The breaking device further includes a second low pressure port at the rear pressure chamber substantially opposite to the first low pressure port, second low pressure channel and a second low pressure accumulator connected to the second low pressure channel. The first low pressure accumulator and the second low pressure accumulator are arranged at the outer circumference of the frame of the breaking device at different positions in the axial direction of the breaking device.

A breaking device includes a frame, an impact device having a pressure chamber with a rear pressure chamber and a front pressure chamber. The breaking device further includes a first low pressure port at the rear pressure chamber, a first low pressure channel and a first low pressure accumulator connected to the first low pressure channel. The breaking device further includes a second low pressure port at the rear pressure chamber substantially opposite to the first low pressure port, second low pressure channel and a second low pressure accumulator connected to the second low pressure channel. The first low pressure accumulator and the second low pressure accumulator are arranged at the outer circumference of the frame of the breaking device at different positions in the axial direction of the breaking device.

A device in a hydraulic rock drilling machine (1) has a distribution valve (7, 7, 7) for controlling hydraulic flow to different parts of the rock drilling machine. The distribution valve has a valve body (8, 8, 8) which moves to and from in an axial direction inside a valve chamber (33). The valve chamber is limited in axial direction by two valve end walls (10, 11; 10, 11; 10, 11). One of the valve end walls is movable in an axial direction against an abutment (12, 12) to define an end position for the valve body, and a pressing device (13, 13, 13) is provided for pressing at least one of the valve end walls against the abutment. A rock drilling machine includes the device.