The limitation of space in early steamships led to the introduction of many ingenious arrangements in their machinery. Important among these were the famous trunk engines that once drove Great Britain’s warships and were in themselves fine examples of marine engineering
AMONG the earliest geared engines were those of the famous iron steamship Great Britain, the first screw steamer to cross the Atlantic. The Great Britain, designed by I. K. Brunel, was laid down at Bristol in 1839. She was launched in July 1843 and her trials were run in December 1844. On July 26, 1845, she left Liverpool for New York. The passage out took fifteen days at an average speed of more than nine knots. The return journey was accomplished in fourteen days. Two fine models of the Great Britain and of her propelling machinery are to be seen in the Science Museum at South Kensington.
THE GEARED ENGINES of the famous Great Britain, built at Bristol in 1839-
The original engines of this ship consisted of four direct-
The valves controlling steam distribution to the cylinders were of the piston type, 20 in. in diameter and operated by single loose eccentrics. These were fitted with toothed rims so that they could be revolved by manually-
The propeller shaft of the Great Britain was in three sections and provides an interesting contrast with the multi-
After many experiments the Great Britain was fitted with a six-
The thrust from a ship’s propeller as it drives the vessel through the water is considerable. In the Great Britain the bearing that took this thrust consisted merely of a steel plate, 2 feet in diameter, against which pressed a gunmetal plate of the same diameter attached to the end of the shaft. The bearing was lubricated by a stream of water.
The engines of the Great Britain had a nominal horse-
In 1847 the original engines of the Great Britain were replaced by oscillating engines built by John Penn of Greenwich. These engines drove the propeller shaft through toothed gearing of particularly interesting design. Four pairs of wheels and pinions were used, placed side by side. The teeth of the wheels were not, however, arranged in straight lines, but were advanced successively a quarter of a tooth, thus making a staggered formation. This type of construction gave smooth running in operation, and strength was ensured by making all four wheels in one piece. A similar method was adopted in constructing the pinions.
Gearing of this type was. frequently used in other steamers and a notable example was the power transmission system of the steamer Simla, built in 1854. This vessel was one of the first P. & O. steamers to be fitted with a screw propeller. The gear ratio was 1 to 2¾ and the large wheel had mortised hardwood teeth meshing with a cast iron pinion on the propeller shaft. The engines were of the “steeple” type with two cylinders. Each cylinder was provided with four piston rods terminating in a crosshead from which a connecting rod descended to the crankshaft below.
Screw propulsion had, from the outset, features of special interest to the designers of warships. In 1842, a small iron steamer, the Mermaid, of 164 tons, was bought by the British Admiralty for experimental purposes and renamed H.M.S. Dwarf. In the following year H.M. sloop Rattler was built by the Admiralty and she was the first screw-
It was in 1842 also that John Ericsson again made a contribution to marine engine history by introducing screw machinery for the first time below the water-
RETURN CONNECTING ROD ENGINES were installed in H.M.S. Agincourt, a battleship built in 1863. The steam-
An interesting type of direct-
The cylinders were placed so that they drove diagonally upwards on to a single crank. The steam chests were on top of the cylinders and each contained two slide valves operated through rocking shafts by eccentrics. The condenser, situated beneath the crankshaft and between the cylinders, formed part of the engine bedplate and contained a vertical air-
John Ericsson, after his invention of an efficient screw propeller, left England for the United States. In 1843 Ericsson’s European representative, Count de Rosen, fitted a direct-
A return connecting rod engine was fitted in H.M. frigate Amphion in 1844. This type was much used in the British Navy for more than thirty years. H.M.S. Amphion’s engines had two cylinders arranged on opposite sides of the crankshaft which was spanned by the twin rods of the pistons. The piston rods terminated in a crosshead from which a connecting rod “returned” to the crank. The symmetrical arrangement of the cylinders was not always adhered to, and many engines of this type were built with the cylinders on one side of the crankshaft.
These horizontal engines presented a splendid spectacle as the rods thrust in and out of the cylinders. Brightly polished cranks flashed as they turned under the drive of the massive connecting rods, and the wonderful array of pump levers and other moving parts gave a fine impression of power and dependability.
Among the wonderful models in the Science Museum at South Kensington are some of special interest. These models, constructed to a scale of one-
H.M.S. Agincourt was a battleship built at Birkenhead by Laird Brothers in 1868. Her return connecting rod engines, built by Maudslay, Sons and Field, exhibited many unusual features. The two cylinders of her engines were steam-
ANNULAR ENGINES, adapted from the type patented by Joseph Maudslay in 1841, were installed in the steam yacht Hebe in 1856. Either of the two vertical cylinders contained a central trunk, through which passed a connecting rod from the crankshaft to the crosshead moving in the four-
A steam expansion valve was fitted to every cylinder. These valves were of the cylindrical revolving pattern designed by J. Field. They were attached to the valve chest at its junction with the main steam-
Two jet condensers were placed opposite the cylinders with two horizontal double-
The engines of H.M.S. Agincourt developed 6,667 indicated horse-
The unarmoured corvettes H.M.S. Boadicea and her sister ship H.M.S. Bacchante were built at Portsmouth in 1875-
The weight of the pistons was considerable and, to prevent undue wear on the lower surface of the cylinder bore, an ingenious sliding arrangement was adopted. Every piston was provided with a plunger at the lowest part of its circumference and this slid backwards and forwards on an adjustable bearing block. The back cover of every cylinder was provided with a projecting “bonnet” to clear the plunger of the piston. The usual twin piston rods were fitted, with the crosshead and its guide bar arranged on the port side of the engine. Steam to the high-
The engines of H.M.S. Boadicea and H.M.S. Bacchante were equipped with hand and steam reversing gear. They exhausted into two surface condensers that contained a total of 10,214 tubes, each ¾-
The engines drove a two-
Annular Screw Engines
Vertical trunk engines were installed in the P. and O. liner Candia, built of iron at Blackwall in 1854. Her engines, built by G. Rennie and Co., had two trunk cylinders of 5 ft. 11 in. diameter and 4 feet stroke, placed in a fore-
A type of screw engine that is generally referred to as an “annular” engine, was patented by Joseph Maudslay in 1856. A set of annular screw engines was built by Maudslay, Sons and Field in 1856 for the steam yacht Hebe, and a fine working model is preserved in the Science Museum at South Kensington.
The engines of the Hebe had two vertical cylinders arranged in a fore-
BUILT AT MILLWALL (LONDON) IRONWORKS, H.M.S. Northumberland, a sister ship of H.M.S. Agincourt, was launched in 1868. She was fitted by Maudslay, Sons and Field with engines of the trunk type with the connecting-
[From part 22, published 7 July 1936]