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 rock drilling arrangement includes an impact device having a frame, pressure chambers in the frame, and a piston arranged in the impact device. The arrangement further includes a rear mounting arrangement for attaching the impact device to a carriage, a front mounting arrangement for attaching the impact device to a machine component, at least one fore pressure accumulator arranged on a front side of the rear mounting arrangement in an axial direction of the piston, and at least one rear pressure accumulator arranged on a back side of the rear mounting arrangement. The fore pressure accumulator and the rear pressure accumulator are connected to one of the pressure chambers and arranged to absorb pressure fluctuations in the pressure chambers.

The rotary-percussive hydraulic perforator includes a body; a shank; a striking piston configured to strike the shank and provided with a braking surface; a braking chamber configured to hydraulically brake the striking piston; a stop piston configured to apply a pushing force on the shank and provided with a bearing surface configured to abut against a stop surface provided on the body, so as to limit the stroke of displacement of the stop piston towards the shank. The rotary-percussive hydraulic perforator is configured such that the bearing surface and the stop surface are axially spaced apart by a predetermined spacing distance simultaneously when (i) the shank bears on the stop piston and is in contact with the striking piston, and (ii) the braking surface is located at an inlet edge of the braking chamber.

An arrangement and method for heating an impact device of a rock treating machine (Rtm) in low-temperature operating conditions is provided. The arrangement includes a warm-up mode (WM) for feeding pre-heated hydraulic fluid through a feed channel to a hydraulic circuit of the impact device. One or more hydraulic accumulators are provided in the hydraulic circuit. The feed channel is provided with a control element for limiting the feeding of the pre-heated hydraulic fluid during the warm-up mode. The control element limits the feeding of the pre-heated hydraulic fluid in the feed channel so that separating elements of the pressure accumulators do not move.

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 device for monitoring pressure within a gas space, which is filled with gas, preferably nitrogen, and/or is prestressed, of a pressure accumulator of a hydraulically driven percussive mechanism having a housing in which a piston is mounted, together with a display element which extends through the face surface of the housing, so as to be slidingly movable counter to the force of a spring, wherein the piston divides the housing into a pressure chamber and a spring chamber. The spring acts on a spring chamber-side working surface of the piston, and the pressure accumulator is at least indirectly operatively connected to the pressure chamber-side working surface of the piston, such that, in the event of a critical pressure within the pressure accumulator being undershot, the piston and the display element are displaced to such an extent that the display element protrudes out of the housing.

A pressure indicator for a hydraulic hammer is provided. The pressure indicator includes a sleeve member configured to couple to an opening defined in a wall housing of an accumulator of the hydraulic hammer. The pressure indicator further includes a plunger slidably disposed within the sleeve member and movable between a first position and a second position with respect to the sleeve member. The plunger includes a first end disposed outside the wall housing of the accumulator. The plunger further includes a flange coupled to a second end. The pressure indicator further includes an elastic member inserted over the plunger and disposed between the wall housing of the accumulator and the flange. A position of the first end of the plunger with reference to an outer end of the sleeve member provides a visual indication of the pressure of the gas within the accumulator.

A hydraulic hammer for impact fracturing a work object includes a hammer shell having a cylinder body disposed between a front head and a rear head. A piston reciprocally movable within the cylinder body abut a work tool and can extend and retract the work tool from the hammer shell. To dampen momentum and impact forces, an accumulator head is attached to the back head and can accommodate hydraulic and dampening fluids in separate first and second sub-chambers. The dampening sub-chamber may directly fluidly communicate with an internal dampening fluid reservoir in the back head.

A pressure accumulator, rock breaking machine and method of storing pressure energy. The accumulator includes a casing and an elastic membrane arranged inside the casing. The membrane divides an inner space of the casing into two separate pressure spaces. A gas space is prefilled with pressurized gas. On the opposite side of the membrane is a hydraulic space for receiving hydraulic fluid. The membrane is a hat-like element having side walls, a mounting flange at its open end and a closed top end. The mounting flange of the membrane is mounted between the casing and a flange element. The accumulator is without a screen. The flange element is provided with a sealing for sealing a piston.

An apparatus for generating impulse-dynamic process forces includes a pressure chamber, a connecting chamber and a bolt chamber The pressure chamber includes a plunger arranged to be pushed into the pressure chamber for compression of a hydraulic medium 1ocated therein. In the connecting chamber there is displaceably arranged a stepped pistons which has a valve body for closing an orifice connecting the pressure chamber to the connecting chamber. In the bolt chamber there is located a displaceable impact bolt which has a first bolt portion and a second bolt portion The first bolt portion seals an interior space of the bolt chamber that surrounds the second bolt portion. Connected to the bolt chamber there is at least one pressure reservoir containing pressurised pressure medium, which pressure reservoir is in communicating connection via a connection port with the interior space of the bolt chamber.