Water engine

Closing a valve too quickly can cause very large pressures to result, and pipework to explode (a phenomenon similar to water hammer), and in addition to valves designed to close slowly, many water engines used air chambers to provide some absorption of force by compressing the air in them.

Even when practical electric motors entered use, water engines remained popular for some years as they possessed several advantages: they were quiet, reliable, cheap to run, compact, safe, and could be relied on to operate reliably in damp or waterlogged conditions unsuited to electrical apparatus, such as powering water pumps in mines, where their ability to continue operating even while completely submerged was a major advantage.

These washing machines, which were very common especially in rural areas until the 1960s, comprised a wooden tub with a rotating cross built into the cover.

This 'star handle' was rotated in regular, to and fro, movements by two pistons which were connected to the water mains.

With the invention of the modern washing machine these washtubs with their water engines disappeared from the market.