The utility model relates to a tension device that is used in a driving spring (1) of the accumulator for an electric circuit breaker; wherein, the driving spring (1) is articulated with a rotating crank handle (2) of a driving shaft (3). The volume of the tension device can be shortened so as to enable the circuit to be better arranged in the electric circuit breaker inside a metallic outer cover. The operation is realized through an implementing case; in the implementing case, the central line of the extension shaft is crossed or tooth crossed with a central line of the driving shaft, and a delivering chain is opened with a space flange or an articulating driving mechanism. |