THE AUSTIN 11 TON CHASSIS.
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A New Model to be Built on Quantity Production Lines.
THE NEW AUSTIN LORRY which has, for some considerable time past, been undergoing exhaustive tests in its experimental stage, has now reached finality in design and-is shortly to be placed on the market. Wei are privileged to give below the eagerly-awaited details of the latest Austin production, which we do not hesitate to say should worthily uphold the enviable reputation earned by -high-class British road vehicles. The design of the 11-tomier is not marked lsrl any outstanding departure_ from accepted practice, the general trend being towards the clean assembly_ of various proven units into one workmanlike whole, in , which general neatness'of lay-ont is the ireniediately noticeable feature.
Ever since the intention to produce this model was first made public as part of the Austin programme for 1920, it has been fairly generally understood that the power unit would be similar to, if not actually the same as, that used in the pleasure cars. No unexpected developments have arisen during the tests to alter the intentions of the designer, and the lorry and car engines are, as a matter of fact, practically interchangeable. Thanks to the Olympia Show and to a steadily-improving rate of delivery, the 20 h.p. engine is now well known, and it is only necessary, therefore, briefly to touch upon its chief features. Its four cylinders are cast en bloc, with a detachable head, and have a-bore and stroke of 3-i ins, by 5 ins.) 95 mm. by 127 mm.), respectively, giving the R.A.C. rating of 22.4 h.p., but an actual brake horse-power of 35 at 1,500 r.p.m.. The joint between the cylinders and the cylinder head is made by means of a
copper-asbestos gasket. Inlet and exhaust valves are all situated on the same aide of the cylinders and are interchangeable. The timing gear is driven by a chain which passes over the crankshaft, the camshaft and the magneto drive.
The chain is of the silent pattern, and is situated at the forward end of the engine. A noteworthy feature is the simple form of chain adjustment provided.
The magneto itself, together with The driving spindld and attachments, is located on a large hinged bracket which is pivoted on a through-bole at a point below the magneto; the top of the bracket is provided with slots which contain studs attached to the Crankcase itself. In order to tighten the chain; it is only necessary to slacken these ten nuts and give the required number of turns to an ordinary set-screw located in the bracket, which presses against 'part of the crankcase, Having obtainea the required chain tension, the nuts are again tightened np, and the whole bracket /locked in position. • • The crankcase is a substantial alnminium casting; and the crankshaft is supported in five bearings. Exhaust and inlet manifolds are combined together, thus providing heat for the incoming gases. Ignition is by high-tension magneto, and' an automatic e,arburetter is standard. Engine lubrication is effected by means of a gear pump, which forces oil through the hollow crankshaft into all the bearings, a strainer being provided at the bottom of the crankcase, through which the oil is strained before . being circulated. The crankcase filler is also fitted with a detachable strainer. Oil pressure is registered by a gauge fitted to the dash, and a level indicator, situated in the crankcase filler, shows the oil level in the crankcase.
Cooling is effected by a gilled-tube radiator mounted in front of the engine, assisted by a high-speed fan, the water being circulated by means of a centrifugal pump situated at the forward end of the magneto drive. „Fuel is supplied to the carburettor from a gravity tank with a capacity for 15 gallons, situated on the dashboard. From the engine, the drive is taken through a single-plate clutch baying Ferodo friction surfaces to a gearbox providing four forward speeds and one reverse. Clutch and gearbox form one unit with the engine, the change-speed lever being centrally placed and operating through a gate, as in the touring car. Contrary to the method adopted on the "Austin Twenty," however' the handbrake lever is situated on the off-side frame member, the grip being placed within convenient reach of the driver's right hand. From the gearbox the drive is transmitted by a propeller shaft to a rear axle driven by an overhead worm.
This axle is of the full floating pattern, the road wheels being carried on, external stationar3k tubes in such manner that the driving shafts themselves are subjected to torsion only. The worm wheel is of special alloy bronze, and the worm itself is hardened and ground true, so that wear is reduced to a minimum. The gearing runs in oil, and an oil filler mounted at the rear of the axle is disposed at such a height that the necessary oil may be maintained at • a constant level.
Both gearing and wheels are carried en roller bearings, heavy thrust bearings being provided to withstand the end pressure from the gearing. Adjustment is provided to take up any wear that may develop. The front axle is forged of high-grade, fatigue-resisting, oil-tempered steel, andthe front wheels are mounted on roller bearings in order to minimise wear and friction.
The frame is of channel sectipn, and is pressed from high-tension steel. Next to the general neatness of design previously emphasized, the most noticeable feature of the chassis is the great depth and width of the main frame members. Ample dimensions have been allowed here, in order that the vehicle may be fully capable of withstanding the strains imposed by the roughest roads. Further, the frame is cross-braced at the rear to prevent transverse di.stortion.
Front and rear axles are both suspended on semi-elliptic springs of generous dimensions, those for the former being 36 ins, long and for the latter 48 ins. long. The road wheels are readily detachable,' and are equipped with 36in. cushion tyres; although pneumatics or olids are offered as an extra. Although the extensive and strenuous tests to which this chaSsis has been put have amply proved it to be a thoroughly sound and reliable vehicle, there is just one modification to the above Specification that may yet be made, but has not been definitely decided, viz., the substitution of twin rear wheels for the single eyes now fitted. The steering is of the worm-and-sector type, and is notable for its lay-out. The Steering column is situated outside the bonnet, and is set at a big rake, the Doter column being supported by a bracket on the dashboard. The extent of the steering rake will be appreciated by the drivers of these lorries, who will experience greater control with less fatigue, than is possible -with a steering column set nearly vertical.
Every chassis supplied will be fitted with a light-pattern driver's cab, which, instead of the usual deep wooden sides, has a eut.away side with .side curtains, adjustable on top and bottom runners, allowing the driver's arm to be extended for signalling purposes without contortional effort.
Standard equipment includes a set of five lamps, speedometer, mechanical horn and tool kit.. Unless otherwise specified, the lamps will -be acetylene head and oil side and tail, but complete electric lighting and starting equipment can be fitted as extras if desired.
In the whole of the chassis nothing that should have been done appears to
have been left undone, and this 4tonner should make an instantaneous appeal to those users of road transport who want a vehicle capable of handling loads which would not pay for the use of a heavier lorry. We conclude this description with the principal dimensions as follow :—Wheelbase, 10 ft. 6 ins.; track, 5 ft.; weight, 34 cwt.; overall length, 16 ft. 11 ins. ; overall width, 6 ft. 1 in.; distance from dash to rear end of frame, 13 ft. 5 ins. ; distance from back of cab to end of frame, 9 ft. 7 ins.; minimum ground clearance, 11 ins., with
36 in. wheels; turning circle, 41 ft. •