These shaft clamping elements consist of just two conical rings which require the minimum of radial space, so providing compact assemblies, and enabling use within small hub diameters. The design offers the maximum versatility of design, but does require the customer to provide their own thrust ring assembly. Whilst only providing low torque transmission per unit they can be combined (up to 4 units) to increase torque capacity. When fully clamped these units provide excellent gastight sealing. Many designs of thrust rings are possible and sketches to the left are two typical designs. These units do not self centre, so require external means of centring the hub.