An electrical impulse operated number wheel counter with coaxial number wheels (2); transfer pinions (8); a reciprocable pawl (12) engaging the first number wheel and a solenoid (20) driving the pawl, has a series of leaf springs (33) carried on the solenoid armature (24). In the rest position the leaf springs (33) engage bosses (9) on the transfer pinions to ensure that the number wheels (2) are correctly aligned but when the solenoid (20) is energised to effect a count, the movement of the armature (24) lifts the leaf springs away from the transfer pinions (8) which can therefore rotate unhindered. An additional effect of the leaf springs is to reduce the power consumption of the counter and this effect can still be achieved with other spring arrangements. A shock resistance element (50) is freely rotatably mounted in the path of the pawl (12) so as to be struck in the event of shock induced movement of the pawl, substantially to eliminate spurious shock induced counts.