A solenoid for actuating a print wire normally biased against the impact direction by novel spiral spring means. Energization of the solenoid coil rapidly moves the print wire in the impact direction against the bias of the spring. Release of the energy supplied to the solenoid coil causes very rapid return of the print wire to the non-printing (i.e., quiescent) position. The novel spiral spring structure experiences a substantially linear spring force upon deflection and provides significantly increased deflection as compared with conventional structures to allow for substantially rapid initial acceleration of the print wire in the impact direction while providing for rapid return of the print wire to the quiescent condition. The mounting of said spring reduces bouncing on overshooting.