Abstract: A rock drill having a hydraulic pressure reservoir formed by the drill housing, and an anvil rotation mechanism enclosed in the housing. A piston of substantial length and a mechanical hydro-operated valve means, provide favorable pulse duration and low impact velocity. The piston has only two sliding seal diameters which permits simplified valve and cylinder configuration. The friction surfaces of the fronthead drill assembly are lubricated and cooled by integration with the circulating hydraulic system. A floating seal cartridge between the piston and anvil, tends to rotate the piston with the anvil to minimize rotative scrubbing at impact.

Abstract: An hydraulic rock drill having an hydraulically reciprocable hammer piston arranged to pound an anvil carrying a drill string. A sleeve type shiftable valve periodically engaged by the piston to effect alternate application to and relief of pressurized hydraulic fluid from the piston cylinder to reciprocate the piston. A constant supply of pressurized hydraulic fluid to actuate the piston is provided by a surrounding reservoir. Hydraulic feed means responds to a predetermined displacement of the anvil relative to the housing to feed the housing relative to the work in accordance with the progress of the anvil. Hydraulic means serves to cushion rebounding actions of the anvil; and means is provided to apply cooling fluid to the sliding surfaces of the tool during its operation.

Abstract: A rock drill having a control valve hydraulically operable to effect feed of oil from a bulk reservoir alternately to opposite ends of a power piston carrying a drill string to reciprocate the piston; having a motor for rotating the piston as the latter reciprocates; having a snubber for absorbing shocks in the event of piston override; and having carriage means automatically and hydraulically operable during reciprocation of the piston to feed the tool along a guide channel relative to the work.

Abstract: A rotatable drill string of a rock drill in which a torsionally elastic shaft provides a rotary driving connection between the drill string and the rock bit for absorbing the usual excessive torque developing in the string during a drilling operation. A lost motion clutch member becomes effective following a predetermined extreme degree of flexing of the torsion shaft to relieve the latter of further added torque load.