Abstract: To secure an operating handle or crank to an operating shaft while inhibiting undesired axial removal of the handle from the shaft, yet permitting controlled removal, for example for repair, a coupling element made of a yielding plastic material, for example of a polyamide resin, is slipped on the shaft, the shaft and the coupling element being formed with interengaging projections and recesses, for example a groove in the shaft and inwardly projecting shoulders on the coupling element. The coupling element itself is slit radially, so that it can be expanded and removed from the shaft by release of the interengaging projections and recesses. The operating handle is formed with recesses to receive axially projecting extensions of the coupling element which engage in the recesses to lock the handle to the coupling element and thus prevent axial removal. Rotation is transmitted between the handle and the shaft by direct engagement of splines and flutes formed on the shaft and the handle, respectively.