Pneumatic drill with polymeric casing and chuck drive components

摘要

A pneumatic drill is provided with a hollow chuck shaft coaxial with one of the rotors which pref. is driven by a reduction gear from a parallel rotor impelled by the pneumatic drive. The casing of the rotors and associated bearings is pref. of metal confined by an external housing of a plastics material (I) which incorporates the hand grips. The rotors are made of a light metal or plastics material. The drive system incorporates a sprinq-loaded valve which is self-throttling at excessive speeds in response to centrifugal effects upon ball bearing spacers between convergent covers.