Steam-hoist.
An elevator or lift worked by a steam-engine, frequently portable. The steam-hoist shown in the cut is a small engine and windlass mounted on a truck which runs on a light track along the wharf. The weight is attached to the lower block of a compound pulley. In Otis's hoist (Fig. 5699), the drum is operated by gearing receiving motion directly from the pistons of the double-cylinder engine; it is grooved, and receives two ropes, one of which winds off while the other winds on, so that the raising of one platform and the lowering of another are effected simultaneously. The platforms are stopped automatically at the upper and lower landings, and the apparatus is provided with an automatic brake, which is brought into action at the moment of shutting off steam. The platforms counterbalance each other, so that the work of the engine is confined to lifting the weight of their contents and overcoming friction. Montgomery's (Fig. 5700) is mounted on a carriage, and is selfpropel-ling; its arrangements are such as to enable it to be used for hoisting, pumping, etc., and also as a traction-engine. In use, the driving-wheels may be lifted from the ground so as to act as fly-wheels, or they may be unclutched The rope drum is thrown into gear with the engine, the piston being driven forward or reversed to wind or unwind the rope from the drum, or the rope may be lowered while a frictionbrake is applied to the drum. Fig. 5701 shows a hoisting-machine for a warehouse-elevator. See also elevator; rope-elevator. |
| Howard's valve-gear for steam-heating apparatus. |
