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.

An impact-driven tool includes a cylinder and a piston slidably inserted into the cylinder and has a large-diameter portion. The cylinder includes: a chamber on one end side; a chamber on the other end side; a communication path that allows the chamber on one end side and the chamber on the other end side to communicate with each other; and a valve chamber that is continuous with one end side in the axial direction of the communication path, and a valve body for piston lifting control that is incorporated so as to be movable up and down and is provided in the valve chamber.

An impact-driven tool includes a cylinder and a piston slidably inserted into the cylinder and has a large-diameter portion. The cylinder includes: a chamber on one end side; a chamber on the other end side; a communication path that allows the chamber on one end side and the chamber on the other end side to communicate with each other; and a valve chamber that is continuous with one end side in the axial direction of the communication path, and a valve body for piston lifting control that is incorporated so as to be movable up and down and is provided in the valve chamber.

The objective of the present invention is to provide a hydraulic breaker comprising: a hydraulic breaker body part; a sensor part sensing vibration generated in the hydraulic breaker body part when objects to be crushed, including bedrocks, are crushed, so as to output a sensing signal; and a control part receiving the sensing signal so as to calculate the time for which the hydraulic breaker body part vibrates, thereby calculating an operating time.

A hydraulic hammering device enables an auto-stroke mode and an idle strike prevention mode to coexist with a simple circuit configuration. The device includes a first control valve to control advancing and retracting movements of a piston, an auto-stroke mode and an idle strike prevention mode, and a second control valve to select either of the auto-stroke mode or the idle strike prevention mode. To the second control valve, a shared spool is slidably fitted and a mode selection means is disposed. When the mode selection means allows supply of pressurized oil to an auto-stroke setting portion of the shared spool and prohibits discharge of pressurized oil from an idle strike prevention setting portion, the auto-stroke mode is selected. When prohibiting supply of pressurized oil to the auto-stroke setting portion and allowing discharge of pressurized oil from the idle strike prevention setting portion, the idle strike prevention mode is selected.

A hydraulic hammering device enables an auto-stroke mode and an idle strike prevention mode to coexist with a simple circuit configuration. The device includes a first control valve to control advancing and retracting movements of a piston, an auto-stroke mode and an idle strike prevention mode, and a second control valve to select either of the auto-stroke mode or the idle strike prevention mode. To the second control valve, a shared spool is slidably fitted and a mode selection means is disposed. When the mode selection means allows supply of pressurized oil to an auto-stroke setting portion of the shared spool and prohibits discharge of pressurized oil from an idle strike prevention setting portion, the auto-stroke mode is selected. When prohibiting supply of pressurized oil to the auto-stroke setting portion and allowing discharge of pressurized oil from the idle strike prevention setting portion, the idle strike prevention mode is selected.

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.

The invention concerns a rock breaking device comprising a striking cell having at least one actuation chamber, a striking piston, and a hydraulic circuit comprising a hydraulic supply source having a High Pressure circuit and a Low Pressure circuit, and an actuator configured to connect the High Pressure circuit or the Low Pressure circuit to the actuation chamber so as to move the piston in translation in the striking cell in a normal movement area of which the limits are variable depending on the pressure difference between the High Pressure circuit and the Low Pressure circuit, the striking cell comprising depressurizing means configured to control the establishment of hydraulic communication between the High Pressure circuit and the Low Pressure circuit when the striking piston exits a predefined movement area.