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B1101 Hot air engine, metal / paint, designed by Horace Robinson, made by Robinson, Manchester, United Kingdom, 1886-1930. Click to enlarge.

Robinson hot air engine

Robert Stirling's engine, which was patented in 1816, was the first hot air engine to be put to practical work. It was envisaged as a safe, easy to operate industrial prime mover to rival steam engines, which required skilled operators and whose boilers could explode, killing or maiming workers. However, its practical use was largely confined to low-power domestic applications for over a century.

Although their thermal efficiency is low, hot air engines run safely and quietly and can utilise …


Object No.


Object Statement

Hot air engine, metal / paint, designed by Horace Robinson, made by Robinson, Manchester, United Kingdom, 1886-1930

Physical Description

The construction of the Robinson hot air engine is a variation of the beta type Stirling cycle engine: the displacer and power cylinders are at right angles to one another and are connected by a single crank such that the two pistons are 90 degrees out of phase, with the power piston leading. The power piston moves horizontally and the displacer piston moves vertically. This 90 degree arrangement makes for a very compact engine, with the power piston's connecting rod weaving its way through the displacer linkage.

Heating is provided by a spirit or coke burner located beneath the displacer cylinder, and water cooling is applied at the cylinder's upper end. This cylinder, in which the displacer piston is a loose fit, acts to transfer air to and from the power cylinder.

The power cylinder is open at one end, and the power piston is directly coupled to the crank-pin by the connecting rod. The closed end of the power cylinder is connected to the displacer cylinder via a transfer tube located under the base plate. The displacer piston acts to transfer air back and forth between the hot end of the cylinder and the cold end, from whence the power piston is supplied through the transfer tube.

The transfer piston is actuated through the following mechanism: a lever is pivoted from upright brackets fixed to the power cylinder; a short link connects the remote end of this red lever with the power piston crank-pin; a second link, which may be called the displacer piston's connecting rod, is pivoted on the red lever and the displacer piston's piston-rod; a flywheel is mounted on the free end of the drive shaft, which is extended to accommodate a power take-off pulley.

In operation, a fixed volume of air is heated. As it gets warmer, its pressure increases. The air acts on the underside of the displacer piston. Having pushed the piston to the top of its stroke, the air is then cooled, reducing its pressure and allowing atmospheric pressure to push the piston back down.

The engine's bore and stroke are both 10 inches (254 mm) and it develops 0.63 horsepower (0.47 kW) when running at 170 rpm. Its thermal efficiency is between seven and ten percent. It is painted green, red and cream.


Cast on front of engine base: ROBINSON PATENT.



Robert Stirling, a Scottish Presbyterian minister, took out a patent for a practical hot air engine in 1816. He is said to have developed it as a safe alternative to steam engines and boilers. Although many forms of hot air engine have been developed since his day, they are generally called 'Stirling cycle engines' to honour his contribution.

Horace Robinson of Manchester patented his hot air engine in 1886 (patent no 11346). The Illustrated Magazine of Practice and Theory described a patent hot air engine designed by A E & H Robinson as a 'useful and thoroughly good motor for driving small machinery'. The firm A E Robinson & Co occupied premises at 78 Great Bridgewater St, Manchester on a site backing onto the Rochdale canal.

The firm L. Gardner and Sons of Patricroft, Manchester, which later made diesel engines, arranged to manufacture the Robinson engine in 1891 and in 1894 made its first Robinson hot air engine under licence.



The engine's provenance is unknown. It was donated to the Museum by Mr G Somerfeldt of Indooroopilly, Queensland, in February 1949.

In 2003, both of the Museum's Robinson engines were taken to a machinery show, where one of them operated for some time. However, the ambient temperature was high and the engine stopped when the temperature differential dropped too low.

A related story by Orrin B Iseminger, who restored a Robinson engine, follows. 'After I finished the re-build, I filled the water reservoir and started it up. Alas, after 20 minutes it slowed to a stop. The cold end had gotten too hot. I tried everything I could think of, but nothing seemed to work. As soon as the water reached boiling temperature, end of show. It seemed as if external cooling was needed, but I didn't ever recall seeing it on a Robinson; and, for sure, I'd never seen it on a model of one. So, I started searching through my pictures of full-scale Robinsons and I finally found the answer. One, and only one, picture showed an external coolant tank connected. Time for a re-design! So, I added the cold water inlet to the bottom. The coolant circulates around the upper end of the displacer chamber. The heated water exits through the original fill hole. The thermo-syphon system provides very good circulation. This made a huge difference in the operation of my engine. It will now run with no load on it, indefinitely, without needing any coolant. The coolant tank will be used whenever a load is placed on it.'


Credit Line

Gift of Mr G Somerfeldt, 1949

Acquisition Date

3 February 1949

Cite this Object


Robinson hot air engine 2022, Museum of Applied Arts & Sciences, accessed 31 January 2023, <>


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