Patent ID: 8147341

Claim:
A drive coupling comprising: an inner plate having a plurality of outwardly extending projections; an outer plate having a plurality of inner peripheral recesses, each of the inner peripheral recesses having two inwardly extending wall portions; and a plurality of coil springs, each of the outwardly extending projections of the inner plate being positioned within an associated inner peripheral recess of the outer plate, with a coil spring being located between one face of each of the outwardly extending projections of the inner plate and one of the inwardly extending wall portions of the associated inner peripheral recesses of the outer plate, each coil spring being fitted over projections which extend inside each coil spring to act as a fixed spring guide and rotational travel stop, thereby limiting rotational travel to a predetermined amount, there being an absence of any coil spring between another face of each of the projections on the inner plate and the other inwardly extending wall portion of the associated inner peripheral recess on the outer plate; wherein rotation of one of the inner plate and the outer plate causes a reaction force in the plurality of coil springs, said reaction force being transmitted to the other of the inner plate and the outer plate to thereby cause rotation of the other plate; the drive coupling further comprising a first retaining plate positioned on one side of the inner and outer plates, a second retaining plate positioned on the other side of the inner and outer plates and connecting means to connect the retaining plates together to thereby maintain the inner and outer plates therebetween; wherein the inner plate has a first shaft formed therewith or attached thereto and the outer plate has a second shaft associated therewith, wherein the first shaft extends through a bearing or bush in the first retaining plate and a spigot on an end of the first shaft extends into a bearing or bush on the second retaining plate to hold the inner and outer plates in fixed axial relationship.