the presence of this lateral clearance can mean that the spacer will run out of centre and lie slightly laterally offset with respect to the pin causing some rotating imbalance if the speed of rotation is not too high this will normally be acceptable but at higher speeds it may be desirable not to have any lateral clearance in that case each retaining pin may have the form shown in fig5 with a spherical portion 22 between waisted portions 24 engaging the sides of the spacer aperture and allowing relative tilting between the pin and the plate as shown while maintaining contact with both sides of the pin aperture in some applications it is necessary to restrict to a minimum relative axial movement between the two shafts and or to transmit a certain axial force from one shaft to the other while allowing for angular and offset abutments betwen the two shafts the location arrangement in fig5 can clearly be modified so as to be effective also longitudinally of the spacer for this purpose the closeness of fit of the spherical portion 22 to its aperture dimension longitudinally of the plate determining whether and to what extent there is relative axial movement possible when in some special cases it is necessary to avoid backlash or lost motion in the axial restraint a preferred arrangement is shown in fig6 in which spacer 30 has two round apertures 32 in which are housed two steel rubber flexible bushes 34 in which the pins are seated these bushes can be of.