STATIONARY ENGINE

A 'stationary engine' is an engine whose framework does not move. It is normally used not to propel a vehicle but to drive a piece of immobile equipment such as a pump or power tool.
This article concentrates on oil-burning or internal combustion engines;
steam-powered engines are described separately in stationary steam engine.

Contents

Overview

Types of stationary engine

Applications

Railways

Farms

Manufacturers of stationary engines

Preserved stationary engines

See also

Overview

Stationary engines come in a wide variety of sizes and use a wide variety of technologies. These include:

★ Power stations of all sizes.

★ Beam engines used in mills and factories before the widespread use of electric power.

★ Winding engines used at mine pitheads.

Types of stationary engine

★ Steam engine

★ Hit and miss engine

★ Hot bulb engine

★ Hot tube engine

Applications

Railways

In Victorian era railway engineering, many attempts were made to replace locomotives by stationary engines, on the grounds that it was inefficient to move something as large and heavy as a steam engine around. These attempts only succeeded where short distances were to be covered, where various kinds of cable railway were successful, particularly for steep inclines (where the inefficiency of moving the engine up and down a hill is particularly significant). A heroic failure was Isambard Kingdom Brunel's attempt to construct an atmospheric railway from Exeter to Plymouth in Devon, England.
Cable haulage did prove viable where the gradients were exceptionally steep, such as the 1 in 8 gradients of the Cromford and High Peak Railway opened in 1830. Cable railways generally have two tracks with loaded wagons on one track partially balanced by empty wagons on the other, to minimise fuel costs for the stationary engine.

Farms

Small stationary engines were frequently used on a farm to drive various kinds of power tools and equipment such as circular saws, pumps, and hay elevators. The engine was fitted to a wooden trolley with steel wheels so that it could be moved to where required, and was then coupled to the equipment by means of a flat belt.
The engines were usually powered by gasoline, but in some cases for economy it was possible to switch over to run on paraffin after the engine had warmed up - to achieve this required a part of the inlet tract to be heated by exhaust gases in order to vaporise the less volatile fuel. Very large stationary engines ran on a heavier type of fuel oil, but this type of engine was usually too large to be moved; typical applications were electricity generation and large-scale pumping.
Initially, such engines mirrored steam engine design in having the piston move horizontally, with the crank and valve gear exposed and employed a drip-feed total loss lubrication system. Later for safety, cleanliness and longevity the design moved towards enclosing the working parts and using sump lubrication.
The four-stroke cycle design was by far the most common, but Petter, a British manufacturer, developed a successful two-stroke cycle design.
A centripetal governor system was usually incorporated to regulate the engine's speed under varying loads. This is a simple negative feedback control system. The engine speed is sensed by a pair of weights that rotate with the crankshaft. As the speed increases, centripetal force causes the weights to move outward against the pressure of a retaining spring. This outward movement is used to restrict the engine power to limit the speed. If the engine slows down, the centrifugal force reduces and the weights are pulled inward by spring pressure, and this movement is used to increase the engine power to maintain speed under increasing load.
The governor can use one of two techniques for controlling speed. Today, most governors open and close a butterfly valve to control the amount of fuel-air mixture entering the engine. However, in earlier engines, the governor would cut off the fuel air mixture completely. These engines are often called "hit and miss" (variously called "hit or miss") because they do not fire on every available power stroke. When the engine is running above a certain rpm, the exhaust valve is held open, and the magneto is prevented from generating a spark. Once the speed drops, the governor allows the exhaust valve to close and the magneto to fire. The engine fires and speeds back up, causing the governor to keep the exhaust valve open again.
On a medium size engine such as a 6hp, the engine can be adjusted so that it only fires every 10 seconds or so when it is not under load. These engines generally drove a wide flat belt to run a firewood cutoff saw, a pump, a reciprocating log saw, etc.
Eventually such engines were rendered obsolete by the development of a universal power take off (PTO) system on tractors, which could drive stationary equipment as well as mounted implements with much higher outputs than the average small stationary engines. For non-PTO equipment the arrival of the reliable electric motor or the small, light, high-speed petrol engine meant that even small machines could be driven by their own motors, making dedicated power units unnecessary.
Live steam models of stationary engines are popular among collectors and hobbyists.

Manufacturers of stationary engines

★ Richard Hornsby & Sons

★ R A Lister and Company

★ Petters Limited

★ Lister Petter

Preserved stationary engines

In the UK there are few museums where visitors can see stationary engines in operation. Many museums have one or more engines but only a few specialise in the internal combustion stationary engines. Among these are the Internal Fire - Museum of Power, in Wales, and the Anson Engine Museum in Cheshire. The Amberley Working Museum in West Sussex also has a number of engines, as does Kew Bridge Steam Museum in London.
Many steam rallies, like the Great Dorset Steam Fair, include an exhibit section for internal combustion stationary engines. These engines have been restored by private individuals and often are exhibited in operation, powering water pumps, electric generators, hand tools, and the like.

See also

★ Canterbury and Whitstable Railway.

★ Hillclimbing (railway)

★ Anson Engine Museum in Cheshire

★ Stationary engine website

★ Stationary engines in South Africa

★ Harry's Old Engine Home Page