Torque indicator ratchet wrench for dentistry

Abstract

This present invention relates to a ratchet wrench and a torque indicator combined concentrically in a single housing. The ratchet wrench is useful for driving a fastener used in dentistry, such as an abutment screw that holds an abutment on a dental implant. In operation, the handle of the wrench can be rotated in one direction (e.g. clockwise) to impart torque on the fastener. When the handle is rotated in the opposite direction (e.g. counterclockwise), no torque is applied to the fastener as the handle is returned to a position where it is easy for the clinician to again rotate the handle to apply additional torque to the fastener. The return motion of the handle (e.g. counterclockwise rotation) may be stepless in operation which is brought about through a coiled clutch spring located in an annular space within a housing between the housing and a concentric driver member. To provide an indication of torque, a rotor body is supported coaxially within the driver member. Torque indicator marks on the rotor body and the driver member indicate angular displacement of the driver member around the common axis relative to the rotor body when a tool held in the rotor body is restrained from turning under load. The housing and with it the drive member may be turned by hand around their common axis when the housing is turned in the latched direction, or a handle fixed to the housing may be used. A lubricating washer is supplied to reduce friction within the ratchet wrench.