A hydraulic hammering device is capable of sufficiently transmitting blow energy to bedrock while further strengthening cushioning action and suppressing damage to equipment. The device includes a pushing piston disposed behind a transmission member and having a smaller propulsive force than that of a main body, a damping piston positioned behind the pushing piston to slide reciprocally forwards and backwards and having a greater propulsive force than that of the main body, a direction-restrictor in a high-pressure circuit between pushing and damping chambers, to which hydraulic fluid is supplied for providing the pistons with propulsive forces, and a fluid supply source. The direction-restrictor restricts an outflow from the chambers side to the fluid supply source side while allowing fluid inflow from the fluid supply source side to the chambers and the pushing chamber sides. A throttle in a drain circuit discharges leaked fluid from a sliding contact location to a tank.

A hydraulic hammering device is capable of sufficiently transmitting blow energy to bedrock while further strengthening cushioning action and suppressing damage to equipment. The device includes a pushing piston disposed behind a transmission member and having a smaller propulsive force than that of a main body, a damping piston positioned behind the pushing piston to slide reciprocally forwards and backwards and having a greater propulsive force than that of the main body, a direction-restrictor in a high-pressure circuit between pushing and damping chambers, to which hydraulic fluid is supplied for providing the pistons with propulsive forces, and a fluid supply source. The direction-restrictor restricts an outflow from the chambers side to the fluid supply source side while allowing fluid inflow from the fluid supply source side to the chambers and the pushing chamber sides. A throttle in a drain circuit discharges leaked fluid from a sliding contact location to a tank.

A cutter assembly for an undercutting machine for cutting a rock workface and a method of assembling a cutter assembly is provided. The cutter assembly includes a shaft mountable on the machine with one end extending from the machine, and a cutter device arranged in connection to the extended end of the shaft. The cutter device is connected releasably and rotationally rigid to the shaft with a locking arrangement. The locking arrangement includes a first locking device arranged to transfer substantially axial loads, and a second locking device arranged to transfer substantially radial loads.

This disclosure relates to a method of mining a rock formation using a disc cutter and a rock breaker tool. Several examples of rock breaker tool are provided, including mini disc cutters and a form of hydraulic striker. The tool is inserted into slits cut into the rock by the disc cutter and activated, causing crack initiation and propagation in the rock.

This disclosure relates to a method of mining a rock formation using a disc cutter and a rock breaker tool. Several examples of rock breaker tool are provided, including mini disc cutters and a form of hydraulic striker. The tool is inserted into slits cut into the rock by the disc cutter and activated, causing crack initiation and propagation in the rock.

A cutter assembly for an undercutting machine for cutting a rock workface and a method of assembling a cutter assembly is provided. The cutter assembly includes a shaft mountable on the machine with one end extending from the machine, and a cutter device arranged in connection to the extended end of the shaft. The cutter device is connected releasably and rotationally rigid to the shaft with a locking arrangement. The locking arrangement includes a first locking device arranged to transfer substantially axial loads, and a second locking device arranged to transfer substantially radial loads.