Patent ID: 6928885
Filing Date: 2005-08-16
Classification: B25B

Abstract:
1. A torque-indicating wrench comprising: a wrench body having a head which is adapted to engage and turn a workpiece about a rotational axis, and a stem which extends from said head in a longitudinal direction radial to the rotational axis, and which terminates at a coupled end, said stem being made from a material with a first modulus of elasticity, and having two outer longitudinal wall segments which are opposite to each other relative to a neutral axis of said stem and which respectively extend in the longitudinal direction; a handle disposed to couple with said coupled end and operable to turn said head about the rotational axis; at least one strainable body, which is made from a material with a second modulus of elasticity that is smaller than the first modulus of elasticity, and which has a gage carrying major wall that is disposed on a respective one of said outer longitudinal wall segments so as to place said strainable body in a position of use where said strainable body is subject to stretching in the longitudinal direction in response to turning movement of said handle about the rotational axis, said gage carrying major wall having inner and outer major surfaces that are opposite to each other and that are respectively disposed proximate to and distal from the respective one of said outer longitudinal wall segments, said inner major surface, in the position of use, being brought into engagement with and being stretchable relative to the respective one of said outer longitudinal wall segments in the longitudinal direction; a restraining member disposed to restrain said strainable body from moving away from the respective one of said outer longitudinal wall segments in a transverse direction transverse to the longitudinal direction and the rotational axis while permitting a stretching movement of said strainable body in the longitudinal direction; a strain gage unit attached to said outer major surface to detect change in resistance values which is a function of extent of stretching deformation of said strainable body as a result of application of torque by said head when said head turns the workpiece about the rotational axis, and to translate the change in resistance values into an electrical signal; a processing circuit connected electrically to said strain gage unit, and calculating a value of the torque applied to the workpiece in accordance with the electrical signal from said strain gage unit so as to generate an output signal; and a display unit connected electrically to said processing circuit for receiving the output signal from said processing circuit and translating the output signal into a visual presentation.