Sidney Straker & Squire, Ltd.
Page 23
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Exhibit —One 5-ton Wagon (loco. type).
.Only one of the ,ix vehicles on exhibition is driven by steam power. This is a 5-ton wagon, known as the company's " traction " type, and is fitted with a loco.-pattern boiler. This boiler is constructed of mild steel, and contains forty ti-inch steel tubes. The heating surface aggregates 58 square feet, whilst the grate has an area of 2.6 square feet. The safety-valve is set to blow off at a pressure of aoolb. on the square inch. Special attention has been paid to the accessibility of the inside of the boiler, and it is a comparatively easy matter to open it up for periodical cleaning, whilst the wash-out plugs are placed as low down as possibk. The boiler is fed by either a direct-acting, slow-speed, plunger pump, driven off the crankshaft, or by an injector. The cones of the latter can be cleaned while the boiler is under steam. The suction pipes of both the pump and the injector are furnished with improved strainers.
The engine is of the compound-horizontal type, and is mounted upon the top of the boiler shell. The cylinders are 4 inches and 7 inches in diameter. by 7 inches piston-stroke. The normal speed of the crankshaft is 400 revolutions per minute. The slide-valves are controlled by the usual link-motion gear, and all wearing surfaces are large. A by-pass, or auxiliary, valve is provided, so that live steam can be admitted to the low-pressure cylinder. The crankshaft is a steel forging 4 inches in diameter, and 3 feet g inches in length. The bearings are of a specially bard bronze.
Transmission is by a double, steel, sliding pinion having two faces with different diameters. Two corresponding spur wheels are carried on a short countershaft, which, also, has a chain sprocket keyed to it. A roller chain passes over the sprocket on the countershaft, and round a large chain wheel which is mounted upon the differential gearing on the live back axle. The axle bearings are of bronze, and have grease pads. The two gear ratios are about 2 and 7 miles per hour, and the
speeds are changed by a single short lever within easy reach of the driver.
The front axle, which is supported upon a semi-elliptical spring, turns about a central steel bolt 3 inches in diameter. The axle reciprocates in a cast-steel jaw, and this allows of a predetermined rocking action. The back or driving axle is made from a hammered steel billet, and the bearings are bolted to laminated supporting springs attached to the main frame members. The wheels are of cast-steel, and the back hubs are fitted with specially long gun-metal bushes. A powerful block brake, acting upon the back wheels, is fitted, and the second brake, as required by law, is found by reversing the engine.
The frame is built up of steel channels, and the transverse stays are strongly braced with gusset-pieces and angles. The galvanised water tank is slung from the rear portion of the frame, and holds 140 gallons. The tank is fitted with a man-hole, three trial cocks, and a large mud-plug.
The vehicle is designed to carry a load of 5 tons at any speed up to 7 miles per hour, and to ascend gradients of one in seven with a full load. Thu vehicle is capable of hauling a trailer loaded with two tons along ordinary roads. The wheel-base is to feet,
whilst the extreme measurements of the wagon are 20 feet, by 6 feet 6 inches. Attention is called to the high quality of material used in the different parts, and, also, to the fact that all the gear is machine cut from cast-steel.