Volume Ten - Pre-Victorian to the present day - even more aspects - The Patent for the Penarth Slipway - 1881 . . .

With this arrangement of machinery, the attendant, by simply working one lever forwards and backwards, can cause the links to travel up and down through a distance determined by the stroke of the rams, which is about 11 ft. Suitable pawls, attached to the main timbers of the cradle, gear with the connecting plates of the links, which are spaced exactly 10 ft. apart, so that at every upward stroke the cradle is hauled 10 ft.

The usual pawls, rack, and centre rails prevent the cradle from returning with the links on the backward stroke. Several sets of pawls are used, so as to distribute the strain on the cradle. The empty cradle is hauled down either by separate hydraulic purchase with ordinary chain, or by a small ram applied within the centre hauling ram, the large rams being locked back during this process.

The machinery on this system erected at Raylton Dixon and Co's, and at Palmer’s Works, is the same in principle as the above; but instead of three distinct hauling cylinders one only is used, fitted with two concentric rams, of which the larger and outer is used for heavy, and the inner for light loads. When the smaller ram alone is being used, the larger one, which is provided with a stuffing-box and gland for the other to work through, is locked back by two removable keys.