Combined Hooke's/Oldham Coupling
This combined Hooke's/Oldham coupling will connect two isometric axles with a misalignment of up to 4mm plus a few degrees of angle at the same time, with minimal backlash. It is efficient, durable, and providing the amount of correction is not excessive, will run effectively at relatively high speeds.
Nut each handrail support to opposing holes in the face of both bush wheels after first placing 3 standard washers and as many electrical (thin) washers as possible on the threads. Push each of the short rods 18b through the handrail supports, which should be adjusted so that the rods slide freely when the nuts on the handrail supports are tightened. The short coupling forms the spider, each short rod passing through a transverse hole and centrally secured by a grubscrew.