Gas engine, horizontal, Dugald Clerk two-stroke, 'Stockport', cast iron/steel, made by J E H Andrew & Co Ltd, Stockport, England, 1882-1892
The Stockport engine has two in-line horizontally opposed cylinders with the two pistons joined by a single piston rod. The power piston is also coupled to the crankshaft through a separate connecting rod. The cylinders, and flywheel, are mounted outboard of the crankshaft bearings, the cylinders being on the opposite side to the flywheel. The cylinders and bearing housings are mounted on a heavy base pedestal. When viewed from the side opposite the flywheel, the power cylinder is on the right. Between the cylinders and the flywheel can be seen the centrifugal governor, driven by a belt from the crankshaft, and the eccentric-operated valve that controls gas flow and ignition. The power cylinder is cooled by a water jacket. Cylinder bore is 165mm and piston stroke is 340mm.
The operational cycle of the engine was described in a leading trade journal in 1885 as follows: 'The engine is comprised of two cylinders horizontally opposed, one being the working cylinder and the other the charging cylinder. The admission of gas to the engine is controlled by a valve composed of two cones on a spindle and regulated by the governor. The method of operation was: during the out stroke of the charging piston, a charge of gas and air is drawn, from the point where they are mixed in the passage, into the charging cylinder. On the return or in-stroke of the piston, the slide valve will have moved sufficiently to open the port through which the charge is driven or forced into a reservoir. The charge is then admitted to the combustion chamber of the working cylinder, through the slide valve. The charge, under pressure, rushes into the combustion chamber driving before it, any non-explosive vapour.' After the air-gas mixture is admitted into the power cylinder it is compressed and then ignition occurs. During the next stoke of the piston the products of combustion expand until the exhaust ports are uncovered by the piston and the residual products are ejected by the incoming charge from the displacer chamber.
Cast in relief on the engine's base: 'J.E.H. ANDREW & COMPANY LIMITED STOCKPORT / SOLE MAKERS / ANDREW'S PATENTS' and below it: 'THE "STOCKPORT" / GAS ENGINE'. The number '376' is also engraved in a gold section on the wheel.