Rotating and reciprocating stone drill - has helical teeth for rotary drive released by multi pawl ratchet system

摘要

An impact drill for stone has a piston with a spindle (7) extending from it which can be rotated as well as reciprocated axially. This travels inside a sleeve (3) forming part of the rotary drive which fits inside the cylindrical casing (1). The spindle (7) has helical grooves (4) along it which engage similar groove in the sleeve (3) which drives it. This sleeve also has a set of e.g. four teeth (5) forming part of a ratchet system engaged by swinging pawls (5) which are held in contact by springs. Two opposite pairs of pawls are housed inside the casing.