Pneumo-percussive drill tool rotor - has tool ratchet indexed by rotor mounted pawl pairs controlled by air cylinders

摘要

A sleeve inside the rotor carries hinged pressure activated pawls which engage a ratchet in the forward area of the drill where it is linked to the tool, to positively rotate this during drilling. Each pair of pawls (39, 40) in the sleeve (38) is rigidly connected on an axis parallel to the central drill axis so that the pawls point opposite ways per pair, and thus rotate the ratchet in these two opposing directions. Pressure is supplied from a compressed air cylinder (44) with piston (45) in contact with the pawls. The compressed air source is coupled up to the cylinders activating the pawls which point in one direction, as compared with the cylinders which activate the opposed pawls and are connected to atmosphere. This disengages the pawls from the tool-turning ratchet.