Dummy wooden model, scale 1:16, of Rigby's double acting steam hammer, from drawings supplied by R G Ross and Son

This is a double acting hammer of the arrangement patented in 1854 by William Rigby.

The cylinder is bolted to a single standard, thus leaving room for work on three sides. The piston and rod are in one forging and the latter has flats on two sides and a dovetailed end for the attachment of the hammer face. The gland and stuffing box are in halves and the former is of such depth as to render external guides unnecessary, The anvil block is dovetailed, like the hammer face, thus readily allowing changes to be made.

Steam is admitted by a hand-worked piston valve. In addition the upstroke of the piston is automatically controlled by a tappet lever connected with the valve spindle and struck by the hammer head.

The anvil block is a separate solid casting which stands up through a hole in the sole plate: it has a broad base resting on a foundation of 1 5 in sq timbers. The sole plate is supported separately on similar timbers with the object of lessening vibration.

The piston rod and hammer face weigh 40 cwt ; the steam pressure used is about 30 lb/sq in.