[Larger plate.]

[345]. Four-guy derrick and winch, used for fixing columns, bases, masonry, &c.

[346]. Fixed post steam crane, for wharfs, piers, jetties, harbour works, &c.

[347]. Portable steam crane, very largely used on wharfs, piers, &c., and sometimes fitted with travelling gear in addition to hoisting and slewing motions.

[348]. Wharf crane, with fixed engine, centre bolt, and trussed arched jib. This is a very good type, as the ground is kept clear for goods, &c., and of course all motions, hoisting, lowering, and slewing are controlled from the crane above ground by hand levers.

[349]. Hydraulic wharf crane, with fixed post. The common type universally used in docks, &c., with the ordinary form of multiplying hydraulic cylinder and chain gear; the valve for controlling its movements is operated by hand levers extending up through slots in the floor; the slewing is performed by a separate cylinder and chain gear, with a distinct controlling lever. See [Sections 42] and [83].

[350]. Hydraulic short lift ram, centre crane, and traveller, employed chiefly to raise the ingots out of the casting pits of Bessemer steel works. The ram is of course subject to severe cross strains, and many designs provide an overhead guide or support for the ramhead.

[351]. Automatic balance crane, portable or fixed; the position of the fulcrum varies with the load.

[352]. Steam multiplying cylinder crane, in which the ram is forced out by steam pressure, acting either directly or by an intervening body of water.

[353]. Breakwater swing crane.