Abstract: Ratchet wrench is a commonly used tool during assembling operation for its reverse characteristic. But the large size and complicated structure of its head make it hard to use when the operation space is limited. A new kind of compliant reverse ratcheting wrench is thus proposed. By introducing a gap and a flexure hinge into the traditional wrench, and its locations are determined based on the geometrical outline analysis. The design principle of key parameters of the compliant reversible wrench is given based on the analysis of the geometrical constraints during the process of releasing bolt and the maximum torque during the tightening bolt process, which makes it possible to achieve the similar function as ratchet wrench so that the compliant wrench can achieve a continues movement during work process to increase efficiency. For its simple structure, the compliant wrench can be fabricated without assembly which lowers the cost. A prototype of the compliant wrench is demonstrated and tested which validates the feasibility of the design.

Key words: compliant wrench, flexure hinge, limited operation space