Catchgear should be of simple but robust design, free acting, reliable and consistent in operation, and finely graduated to reduce to a minimum the free drop-back of the conveyance.

The Reliance–Worrall catchgear comprises toothed racks affixed to and extending down two sides of the conveyance, together with associated pawl boxes mounted in the headframe in a position relative to that of the racks of the conveyance.