Elevator

Machine by which a platform or cage is lifted from one level to another in a building. The simplest forms are large dumb-waiters, operated by hand. Power elevators are driven by belting from a shaft, open and cro ed belts being shifted from loose to fast pulleys to drive a worm and wheel to wind or unwind the rope; larger sizes have their own independent reversible steam or gas hoisting-engines, or are hydraulic elevators. In the latter, water is pumped to a tank at the roof of the building, and its head gives the power to drive a piston which actuates the hoisting-rope. The head of water acting from the height may drive a multiple purchase with short piston stroke. Where the elevator is not to be in constant motion the hydraulic principle has great advantages, and works more smoothly and often more rapidly than the other designs in any case. The term elevator is also applied to the establishment where grain is stored and by whose machinery the grain in bulk is loaded and unloaded from ve els or cars. Systems of buckets on endle belts lift the grain out of the hold or car, endle belt conveyors distribute it into elevated bins, from which chutes deliver it, when graded, by gravity into the shipping ve el. In flour mills the elevator is a similar system of buckets on an endle belt, by which material is lifted from floor to floor.