New Arrol-Johnston Car Co., Ltd.
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Principal Exhibits:—One 2-ton and one 3-ton Chassis; covered Van; Lorry; Omnibus.
Chief amongst the interesting exhibits of the company is the 24-3oh.p. chassis for loads of 3 to 4 tons. The vertical engine has four cyiinders, cast separately, with a bore of _a inches diameter, and a piston-stroke of 5 inches, In addition to the cylinders being cast separately, the cylinder-head and valvechest is not cast with the cylinder, but is attached thereto by six studs. The advantage claimed for this arrangement is that, should anything go wrong with any part of the cylinder, a complete new cylinder is not required, but only a part. For instance, should the valve seats become worn owing to continual re-grinding, it is not necessary to replace by a whole cylinder casting, but merely by a new valve-chest. The joint between the two is a copper one, and forms the upper portion of the copper water-jacket. The material used in the construction of the cylinders, pistons and combustion chambers is of close-grained cast-iron, and the waterjackets are of spun copper, corrugated to permit of expansion without any strain on the joints. These are made by letting the jacket into a recess in the .cylinder casting, and caulking in three rings of copper wires, and afterwards running solder in to fill up all the interstices. The inlet valves are placed over the exhaust valves, giving a minimum of wall surface to a maximum of compression space. All valves are mechanically operated, and, by simply slackening two nuts, and swinging back a bridge-piece, the valves may be taken out and examined without disturbing any of the tappet gear. The crank case is of aluminium, and has a large sump : this sump contains two gallons of lubricating oil, and is fitted with a g-uage-glass to indicate
the quantity of oil which is in it at any rime. Forced lubrication is employed, the supply being kept up by an oil pump, operated from the crankshaft. There is a remarkable absence of lubricator pipes, all oil-channels being made in the castings and machined parts. The bottom half of the crank case may he easily removed, exposing to view the whole of the connecting rods, bearings, camshaft gears, -etc., without in any way disturbing any of the parts. The camshaft, cam casing, valve-lifter and their guides may be removed as a whole without disturbing other parts. The engine develops 241*.h.p. at nsor.p.m. Duplicate ignition is fitted; high-tension jump spark, with coil and accumulator, and the "Arrol-Johnston" low-tension magneto. The company m.akes its own sparking plugs. The Hele-Shaw friction-disc clutch is fitted to all vehicles of the company's make. The gear-box has four speeds forward, giving direct drive on top speed, and one speed reverse. The box is suspended by a swivelling, three-point support which does away with all twisting strains due to bad roads. The revolving mass of the first-motion shaft has been kept as low as possible, in order to ensure silent changing. The company's own roller bearings are used, and the shaft-lubrication is automatic.
The differential shaft is of special
design, and is carried on the long tubular radius rods which we illustrate on this page. The top half of the differential case may be removed for inspection purposes without disturbing the shafts. this feature also applies to the gearbox. The pull of the chains is taken up by roller bearings, and the chains are enclosed and run in oil-baths, the offside one of which is shown above.
The hind axle is of nickel steel, and has plain bearings, and lateral motion is prevented by the company's patent parallel-motion radius rods. Two independent sets of brakes are fitted, both of the internal-expanding type. The hand-leer brake oP0.40_tes on the inside of the -chain ringaljolted to the rear road-wheels. All brakes are particularly easy of adjustment ; the blocks are interchangeable and simple to renew.
The radiator is of the gilled-tube type, with cast water-vessels, top and bottom, which are identical. No fan is fitted, but the arms of the fly-wheel are shaped to act as a fan. The frame is of channel steel, and no secondary frame is used; substantial cross-stays are provided as may, also, be seen in cur illustration of the radius rods. All gearing throughout the vehicle is machine-cut, and all plain bearings are of hard gun-metal.
In addition to the 24-3oh.p. chassis, the company is showing the following : A double-deck omnibus on a similar chassis ; a I2-15h.p. 2-ton commercial vehicle chassis; :a t2-15h.p. lorry for a 2-ton load ; and a 12 -I5h.p. covered van for t-ton loads. All these chassis have the Tourist Trophy type of engine, with
two horizontal cylinders and four pistons. The bore of the cylinders is a+ inches in diameter, and the pistonstroke is 5 inches. In other respects the general arrangement of the chassis is on the same lines as the 24-30h.p., but all parts are proportioned according to the loads. Examples of both 12t5h.p. and 24-3oh.p. engines are, also, exhibited on the stand. A large num ber of vans and lorries are now running very successfully, and giving complete satisfaction to their owners.