Water-Lifting Device

a water lift used for transferring fluids, mainly water.

In the past the term“water-lifting device” was used to describe all technological means for transferring water, including pumps. At present the term is usually used for machines and devices that transfer fluids mainly by changes in the potential energy of their position. The simplest water-lifting devices consist of a crane and a hoist for lifting water from wells. More complex devices, including Archimedes’ screw, the waterwheel, and the bucket conveyor, provide continuous flow of large volumes of water.

Archimedes’ screw consists of a housing or a trough and a screw, which rotates (about 50 rpm) from a wind engine or other engine. The screw is installed at an angle of about 40° to the horizontal, and one end is submerged under the water. During rotation the screw surface puts pressure on the fluid and transfers it along the housing or trough, lifting it 3 or 4 m.

There are several forms of waterwheel. Basically, the waterwheel has freely suspended buckets that fill with water below and empty the water (tipping over) over the trough, or the buckets may be replaced by blades. The buckets are used for transferring large amounts of water up 2-6 m; they take their power from wind engines or other engines. The bucket conveyor is used to lift liquids up to 25 m; the working element of a bucket conveyor is an endless chain with buckets attached to it.

There are devices similar to the bucket conveyor, called chain pumps or flange or cellular belt conveyors, in which the fluid is taken up by compartments on a continuous chain or belt. The fluid is kept in the compartments by the force of surface tension. At the present time water-lifting devices are used in underveloped countries, where they are still used for irrigating or draining land and other similar work.