The St. Pancras Iron Work Co., Limited.
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Exhibit:—Standard 5-ton Wagon.
The exhibit of this company consists of a standard steam wagon designed to deal with a load of 5 tons on its own platform and a further 3 tons on a trader. The approximate dimensions are :—overall length, IS feet 3i inches; overall width, 6 feet 6 inches; and overall height, 9 feet 8 inches. It has a platform area of 12 feet by 6 feet 6 inches which may, if necessary, be increased to 13 feet by 7 feet. The boiler is of the vertical, returntube type in which, wherever possible, fiat surfaces have been eliminated with the object of avoiding all expansion troubles and leakages. It is claimed that the St. Pancras boiler embodies all the advantages, while eliminating all the disadvantages, of the vertical water-tube boiler, and the loco.-type tire-tube boiler. The hemispherical fire-box prevents deposit on the upper surface, and is shielded front cold draughts of air owing to the central firing system. The gases pass into a combustion chamber, through the lower set of radial tubes, being baffled by an exhaust superheater. 1 hey next reach the smoke-box, by way of the upper " return " tubes, which are completely submerged, even on a gladient of one in six, with half a gauge glass of water showing. The concentric arrangement of the drums dispenses with expansion troubles. The heating surface is 92 square feet, and the makers guarantee the workmanship and material : they maintain that the boiler is as nearly "fool-proof " as possible, taking all the requirements into account. It is capable of evaporating r,000lb. of water per hour, and the working pressure is 220lb. per square inch, but the boilers are tested to a pressure of 35o1b. per square inch. The fittings comprise a " Klinger " water-gauge, a safety-valve, two check-valves, a blow-off cock, a blast cock and a water lifter. Water is fed to the boiler by a feed-pump driven from the engine at a reduced speed, through machine-cut gear wheels, and so arranged that the engine can be run to Iced the boiler when the vehicle is ac rest. A Gresham and Craven injector is also fitted.
The engine is of the horizontal-compound typo, with cylinders 4 inches and 7 inches diameter of bores, and with a piston-stroke of 64 inches. Both cylinders are lagged with non-conducting material, and covered with sheet steel. The link-motions are deeply case-hardened, and bearings and other wearing parts are of ample proportions, and allow of adjustment for wear.
The crankshaft is made from a solid steel forging, whilst all working parts of the engine and gearing are enclosed in an oil-tight and dust-proof case, provided with inspection doors for access to all parts at any time. The engine indicates 6oh.p. at normal revolutions per minute. The gear teeth are all machine-cut from the solid blanks, and provide for two speeds of 3 and 6 miles an hour.
The following is a short description of the St. Pancras high-pressure arrangement. The casing shown on the line drawing is mounted on the lowpressure cylinder, the passage on the right-hand communicating at the bottom with the exhaust space, and, at the top, with the exhaust pipe. The opening on the left-hand is the inlet to the I.p. steam chest. The exhaust steam from the h.p. cylinder is led into the space between the two valves, which are shown in compound position. By means of the spring shown to the right, and the controlling cylinder and piston shown to the left, the egress of the h.p. exhaust can be either directed to the I.p. steam-chest or to the main exhaust. When it is desired to work both cylinders h.p., steam from a pilot valve, close to the driver's hand, is admitted behind the controlling piston, and, by compressing the spring, moves the valves to the right, thereby opening the receiver direct to exhaust and closing the communication to the I.p. cylinder. At the same time, by means of the rocking lever, the valve shown at the top is opened, thus admitting steam direct from the boiler to the I.p. steam-chest. The peculiar advantages of this arrangement are that no stifling boxes are required, which, by causing spindles and valves to stick, may defeat the object in view, and the valves are positively seated, with A pre-determincd pressure, apart from any judgment on the part of the driver. The mushroom type of valve employed can be kept absolutely steam tight, which cannot be said of plug or slide valves.
The differential-geared countershaft may be " locked," thus rendering the differential gear inoperative, and giving the vehicle a much better chance to extricate itself from a difficult situation. The final drive, from countershaft to rear wheels, is by means of
24-inch pitch, roller chains, and these are of extra width to ensure durability-.
The back axle is a mild-steel forging, and on its ends are mounted the caststeel driving wheels and chain rings. The rear wheels are 3 feet 3 inches in diameter by io inches wide on the tread, and the leading wheels are 2 feet 9 inches in diameter by 6 inches wide. Another special feature of the St. Pancras steam wagon is the patent, rocking, double-pivoted, fore-carriage. This gives a three-point suspension to the wagon, as is the usual practice with traction engines, and permits either of the leading wheels to ride over large obstacles on the road without subjecting the frame to any twisting. It ofiers all the advantages of the -Akermann steering, and is actuated by a hand wheel and gear from the footplate in the usual manner. The leading, like the driving axle, is made from a solid mild-steel forging. The brakes consist of a powerful screw brake acting on the rear wheels, and, also, the reversing of the engine.
The frame is of channel steel, suitably stayed and braced by cross-members and gussets. The water-tank has a capacity of 16o gallons, and for rapidly filling this there is the waterlifter and 25 feet of suction-hose inch in diameter.
The address of the St. Pancras Iron Work Co, is 171, St. Pancras Road (near King's Cross), London, N.W., and the wagon is built there.