Portable engine

Before that, most power generation and transmission were by animal, water, wind, or human; after that, a combination of electrification (including rural electrification) and modern vehicles and equipment (such as tractors, trucks, cars, engine-generators, and machines with their engines built in) displaced most use of portable engines.

They were used to drive such barn machinery as pumps and hammer mills, bone-crushers, chaff and turnip cutters, and fixed and mobile threshing drums.

William Tuxford of Boston, Lincolnshire started manufacture of an engine built around a locomotive-style boiler with horizontal smoke tubes.

A large flywheel was mounted on the crankshaft, and a stout leather belt was used to transfer the drive to the equipment being driven.

In 1852, the company won a gold medal for a portable engine at the Royal Agricultural Society's Gloucester show, and thereafter the business expanded rapidly: they established a second works, in Vienna in 1857, to target the European market, and by 1890 the company had manufactured over 26,000 portable engines, many being exported all over the world.

[2] In the 1850s, John Fowler used a Clayton & Shuttleworth portable engine to drive apparatus in the first public demonstrations of the application of cable haulage to cultivation.

The English builders produced in the order of 100,000 portable steam engines in the hundred year time period both for home use and export abroad.

Apart from threshing work, portable engines were used to drive corn-mills, centrifugal pumps, stone-crushers, dynamos, chaff-cutters, hay-balers and saw benches.

As of 2007, there are still examples of such dismantled portable engines working commercially in small rice mills in Burma[7] (and, no doubt, elsewhere too).

Such examples are easy to identify due to the curved saddle, below the cylinder block, that was used to mount the engine to the boiler.

This layout was designed to position the regulator close to the firebox, making it easier for the engineman to maintain the fire and control the engine speed from the one location.

An added bonus is that the flywheel is clear of the rear road wheels so the latter can be set on a narrower track, making the engine easier to manoeuvre through field gates.

This latter type were also known by British manufacturers as 'colonial' boilers, as they were mainly intended for export to 'the Colonies', and had a high ground clearance for travelling along rough tracks.

A smaller flywheel provides a slower speed for farmyard work (e.g. chopping feedstuffs) than is required for driving a threshing machine (for example).

The crankshaft drives a boiler feedwater pump which draws water from a barrel placed alongside the engine.

Many engines have a simple, but effective, feedwater heater which works by blowing a small portion of the exhaust steam into the water barrel.

This is because they are mounted on the swivelling fore-carriage, under the smokebox, and large wheels would be liable to hit the boiler when the engine was turned around a corner.

At the Great Dorset Steam Fair, for example, portable engines may be found in the relevant demonstration areas driving saw benches, threshing machines, rock crushers and other contemporary equipment.