A Beer Engine, also known as a hand pump, is a uniquely British dispensing device that is specifically appropriate for traditional cask-conditioned ales. The beer engine is a piston pump that allows the casks to be kept in a cooler cellar below the bar and the beer to be pulled or drawn up to the bar. Cask-conditioned beers have lower carbonation than standard beers because they are usually served at about 11°C to 14°C (approximately 52°F to 57°F). If a cask-conditioned ale were served through a standard dispensing system, the gas pressure and colder temperature would increase the carbonation of the beer, which would then lose its ideal balance of flavors. See cask conditioning. Conversely, dispensing fully carbonated beers with a beer engine would yield relentless foam. A simple gravity tap is suitable for a cask-conditioned ale if the proper cask temperature can be maintained, but a beer engine is imperative if the cask is in a remote location. See gravity dispense.

A version of the beer engine was patented by the prolific British inventor, locksmith, and hydraulic engineer Joseph Bramah in 1797. The modern beer engine has changed little since the early 1800s; it consists of a simple piston attached to a long, sturdy handle. Check valves assure that beer flows only in one direction, up from cask to glass. Traditionally, all beer engine parts were made of brass, but a British law passed around 1990 mandated that all parts in contact with beer henceforth had to be made of plastic or stainless steel. Beer engines are designed to dispense a half or a quarter (Imperial) pint per pull. Proper beer engine installations have some measure of cooling all the way up the beer line and the piston chamber should be insulated. Operating a beer engine in a busy pub is hard physical work, requiring patience, skill, and muscle. Experienced bartenders will switch back and forth between using their right and left arms to pull pints—otherwise they may suffer the so-called barman’s bicep, where one arm grows noticeably larger than the other.

See also swan neck.