A beer engine, also known as a handpump, is used to pump the beer from the cooler. The beer engine is a , airtight piston chamber; pulling down on the handle raises the piston which drags up a half pint of beer. When a cask is first tapped into the beer engine, or after the lines have been washed through, the pump needs to be pulled several times to clear the lines of air or water. The line will continue to hold beer, which will tend to go stale overnight, so the first beer pulled through will be bad beer, and this will be simply thrown away. Most pubs will pull through at least a pint of beer on each beer engine before they open, while others will wait for the first order of beer on that pump before pulling through. Experienced bar staff will serve a pint with long, smooth, slow pulls of the pump handle, plus a short final pull just to make sure the glass is full.
A small flip tap and a short spout is the standard neck for dispensing cask ale. An alternative is a long spout with a tight 180° turn, called a “swan-neck”, which is designed to force the beer into the glass, agitating it so that a fuller head is created. Some drinkers disapprove of swan-necks, believing that flavour is reduced.
In some pubs a small device or cap is fitted to the end of the spout rather like a sprinkler at the end of a hose pipe. The device is known as a “sparkler”. Like the sprinkler at the end of a hose, this can be twisted to regulate the flow of the beer. When the sparkler is tight, the beer is severely agitated resulting in a large head but a significant loss of flavour and mouthfeel.]This is most common in the north of England and Wales. Many drinkers in the north prefer their beer this way; it is softer and creamier with less bitterness. Drinkers in the South tend to prefer their beer with a touch more bitterness, and a slightly harder mouthfeel.
Some pubs disguise keg beer by having an imitation pump handle on the bar. If the bar staff have merely turned on a tap, or are just resting their hand on a very small handle with no pump action, then this is a keg beer. Exceptions are some pubs (in the north and occasionally elsewhere) which use electric pumps or the pubs in Scotland that use traditional air-pressure founts[5] on cask ale.
It is considered perfectly acceptable to dispense beer directly from the cask, as in pubs which have a tap room rather than a cellar. Gravity dispense is often used in beer festivals as well.
