This is a model of an engine and boiler of the high pressure type patented by Richard Trevithick and Andrew Vivian in 1802, and made by Hazeldine & Co. of Bridgnorth between 1803 and 1808; probably in 1805.
The original engine and boiler were found in 1882 at Hereford among scrap iron, by Mr. F.W. Webb, of Crewe and missing parts were restored by him. The engine is now preserved in the Science Museum, London.
In the original the boiler shell is of cast-iron, 56ins. long, 45ins. diam. and 1in. thick, supported on two cast-iron stools. The back end is dished, while the front end is flanged to allow the wrough-iron front to be bolted on. To this front is riveted the horseshoe flue, one leg of which is 18ins. inside diam. and accommodates a grate 5 sq.ft. in area; while the other leg is tapered from 12.6ins. inside diam. to 11.25ins inside diam., and joins the chimney. There is a manhole with cover on the boiler front, but the whole front can be removed, so as to gain access to the interior. On the top of the boiler is a safety valve, the area of which is 3sq.ins.: figures marked on the lever, with the weight shown, indicate that the pressure was 52lb.per sq.in.
The steam generated is fed to a hand adjusted throttle valve situated in the valve chest of the steam cylinder which is sunk vertically in the boiler, and secured by an upper flange. The steam is admitted on the cylinder by a four-way cock, worked by a tappet from the crosshead: from the latter of two connecting rods return to the cast-iron crankshaft below the boiler. The cylinder is 6.37ins. diam. by 30.5ins. stroke. The exhaust steam passes through a Trevithick pipe feed-header.The fly-wheel is 9ft. diam. with a balance weight cast in.
At a pressure of 50lb. per sq.in. and say 50 r.p.m., the original engine would develop about 7.5 h.p.
Record number BDNNM:1000-309