Axial Steam Engines.

THE PROPOSED SCHOTT ENGINE: 1870

Above: The Shott Axial Engine: 1870. Model in tHe Science Museum, London. Author's photo.

This is a demonstration model of a proposed marine steam engine built by George Shott (of Messrs. John Penn and Sons) with the assistance of his two sons George and William Nesbitt Shott. The full-size version was to have two cylinders of 36 in diameter by 18 in stroke, fitted with piston rods and rollers to engage with grooves in two cylindrical cams mounted on the propellor shaft. Two similar but smaller cams on a separate shaft, driven by gears from the main shaft, operated the steam admission and exhaust valves. The propellor shaft passes through the centre of the aft cylinder and piston, and was to be fitted with a four-blade bronze propellor of 7.5 ft diameter. There is no provision for a thrust bearing on the model.

The engine was expected to develop about 520 indicated HP at 120 rpm, with steam at 25 psi. Its claimed advantage was presumably that the fore-and-aft engine format would fit better into a ship hull. No record of full-scale construction has been found.

THE WEST ENGINE: 1878

Left: The West Axial Engine: 1878. This article claims that West's engine was "now well-known". Here it is driving a Gramme electrical generator at 700 rpm. The engine has six cylinders and a centrifugal governor, but that is about all we learn here. No US patent for this engine has been found. From "The Engineer" 25th January, 1878

Left: The West Axial Engine: 1878. The West engine makes a cameo appearance in a big two-volume book called "Modern Power Generators", which is famous for its coloured fold-out illustrations. According to Mr French, "A speed of 1000 rpm has been satisfactorily obtained in practice, but the engine is not now manufactured." That was in 1908. From "Modern Power Generators" by James Weir French, Vol 1, published by The Gresham Publishing Co in 1908

A SIX CYLINDER AXIAL STEAM ENGINE: 1884

Left: Six-Piston Axial Engine: 1884. This engine appears in Knight's Dictionary without any attribution, but looking at the unusual piston construction in the drawings above, it is almost certainly West's engine. This engine has six cylinders pushing on a swashplate or disk. Mr Knight says: "The pistons are single-acting, the pressure of steam in the cylinders tending always to force them against the disk. The shaft makes one revolution for each complete double-stroke of each piston, and as each acts during the same revolution, the six going into operation successively at intervals of 60 degrees, it follows that three pistons are constantly acting on the disk. The strain thus thrown upon the crank and shaft is practically uniform, and there being no dead point, no flywheel is necessary." Note the horizontal governor to the left of the engine, in front of the output pulley. From "Knight's Practical Dictionary of Mechanics: Supplement" by Edward H Knight, published by Cassell & Co in 1884, p819

Left: Six-Piston Axial Engine: 1884. The steam admission and exhaust appears to be controlled by a rotary valve K to the right of the engine. No means for varying the cut-of can be made out. From "Knight's Practical Dictionary of Mechanics: Supplement" by Edward H Knight, published by Cassell & Co in 1884, p819

THE KNICKERBOCKER AXIAL ENGINE: 1889

Left: Knickerbocker Four-Piston Axial Engine: 1899 "A four-armed yoke is socketed on a centre common to the four pistons. Its spindle is a crank pin, and makes a conical circuit with the crank and shaft. The ends of the yoke are socketed to the pistons by connecting rods. The pistons take steam successively, making a continuous pressure on the circuit of the crank." The steam admission appears to be controlled by a disc valve to the left. From "Mechanical Movements, Devices and Appliances" by Gardner D Hiscox, published by Sampson Low, Marston & Co in 1899.

Extensive searching has so far failed to unearth any US patent covering this engine.

THE PIONEER AXIAL STEAM ENGINE: 1903

Left: The Pioneer Axial Engine: 1903 This four-cylinder axial engine (or rather two of them) powered the Pioneer steam lurry, which is apparently how you spelt "lorry" in 1903. There were two such motors compounded, one high-pressure motor and one low-pressure motor. They were very similar (though presumably the cylinder dimensions were different) and each drove one of the front wheels independently through a vertical shaft and bevel gearing. The rear wheels were the steering wheels, on the Ackermann system. It must have been an interesting vehicle to drive. This is a wobble-plate rather than a swashplate engine, as the wobble -plate does not rotate- clearly it couldn't without tying the connecting rods into knots. The wobble-plate is at D, and carries gear-teeth D1 that engage with teeth E1 on the casing to stop it rotating. It also carries a smaller ring of teeth at D2, which engage with the teeth F on the output shaft F2. I quote the source: "In this 'seeking-tooth' type of gear the resulting speed of the vertical drive shaft is the difference between the number of teeth in two gear wheels; wheel D2 having 42 teeth and wheel F only 39; the speed reduction is in the ratio of 14 to 1." Note that the only date I have is that of the book below. It does not give the name of the inventor or the country of origin. From "The Automobile" ed Paul N Hasluck, published by Cassell & Co 1903, p101. It was based on a book by Lavergne.