Pulverized coal Grain leg

A bucket elevator, also called a grain leg, is a mechanism for hauling flowable bulk materials (most often granulated ore or pulverized coal) vertically.

It consists of:

1 Bucketsto contain the material;

2 A belt to carry the buckets and transmit the pull;

3 Means to drive the belt;

4 Accessories for loading the buckets or picking up the material, for receiving the discharged material, for maintaining the belt tension and for enclosing and protecting the elevator.

A bucket elevator can elevate a variety of bulk materials from light to heavy and from fine to large lumps.

A centrifugal discharge elevator may be vertical or inclined. Vertical elevators depend entirely on the action of centrifugal force to get the material into the discharge chute and must be run at speeds relatively high.

Inclined elevators with buckets spaced apart or set close together may have the discharge chute set partly under the head pulley. Since they don't depend entirely on the centrifugal force to put the material into the chute, the speed may be relatively lower.

Nearly all centrifugal discharge elevators have spaced buckets with rounded bottoms. They pick up their load from a boot, a pit, or a pile of material at the foot pulley.

The buckets can be also triangular in cross section and set close to on the belt with little or no clearance between them. This is a continuous bucket elevator. Its main use is to carry difficult materials at slow speed.

Early bucket elevators used a flat chain with small, steel buckets attached every few inches. Current construction uses a rubber belt with plastic buckets. Pulleys several feet in diameter are used at the top and bottom. The top pulley is driven by an electric motor.

The bucket elevator is the enabling technology that permitted the construction of grain elevators. A diverter at the top of the elevator allows the grain to be sent to the chosen bin.

A similar device with flat steps is occasionally used as an elevator for humans, e.g., for employees in parking garages. (This sort of elevator is generally considered too dangerous to allow use by the public.)