A NEW COACH CHASSIS FR( A MOTORCYCLE FACTORY.
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11 Particulars of an Entirely New Sixinder-engined 26-seater Bus and Coach assis Produced by A. J. Stevens and Co. (1914), Ltd.
WOLVERH AMP TON bids fair to become, in the near future, a very important commercial-vehicle manufacturing centre, for we are now able to announce the entry of another private-vehicle manufacturing concern into the commercial side of the industry. It will be recalled that in December last the Sunbeam Motor Car Co., Ltd., introduced two large chassis. Now the A.J.S. motorcycle concern is producing a 26-seater bus and coach chassis, which is something of a departure from the normal activities of tile company, at any rate, so far as recent years are concerned.
_ It must not be thought, however, that the manufacture of vehicles other than motorcycles is entirely new, either to the directors of the company or to many of their employees, because certain of the older hands (including Mr. Harry Stevens) have been connected with the industry right from the start. Indeed, it was in 1897 when Mr. Harry Stevens made his first internal-combustion engine, which preyed to be the forerunner of that fitted to the present A.J.S. motorcycle. Later on the original company manufactured single, twin and four-cylindered engines for cars and other uses, so that the production of a bus chassis is not so far removed from past activities as might be thought at first.
When the company's achievements in the motorcycle racing world are taken into account, it is not surprising to find that the new bus and coach chassis is powered by an overhead-valve high-efficiency sixcylindered unit, and that the lines of the chassis have been so planned that an almost sporting appearance for the complete vehicle can be obtained if desired. Indeed, after a lengthy talk with Mr. C. W. Hayward —who is largely responsible for the enterprise—we gathered that very special attention has been paid to the matter of appearance, and, as will be seen from the photographs of the vehicle fitted with a test-rig cab, the lines of the bonnet, scuttle and wings are distinctly pleasing.
Looking around the chassis one cannot help but he impressed by the general simplicity and neatness which characterizes the whole layout. The main frame, for instance, although of ample proportions to take the B32 load for which it is designed, does not appear to be obtrusive or clumsy, whilst such items as the mountings for the front and rear axles, the brake controls, etc., are neatly arranged, despite their substantial dimensions.
Before actually describing the main details of the layout it would seem opportune to state that the chassis is primarily intended for high-speed, longdistance work, either as a 26-seater bus or as a 20-seater coach, the latter, of course, having roughly the same size of body as the former, but with the seats spread out to give greater comfort and roominess for each passenger. Efforts, too, have been made to provide light controls, and from a personal trial of the vehicle on the road we are able to teStify that this quality has been achieved, for the controls handle in a manner closely akin to those of a large private car.
With a useful load of two tons we were able to exceed 55 m.p.h. in top gear under slightly favourable conditions. At more reasonable rates of travel—say, between 40 m.p.h. and 50 m.p.h.—the engine settled down to a pleasant hum and gave us the impression that it could pull all day long at such speeds without tiring or becoming noisy.
Turning now to a consideration of the chassis in detail, as we have already said, sturdiness is a notable characteristic of the design. The main frame, for
Instance, is 8 ins, deep in the centre and the sidemembers are tied together by no fewer than five channel-section cross-members, each having very deep gussets at the points of attachment to the main frame, so that the load is spread out over a big surface—an arrangement which avoids local stressing. A deep upsweep over the rear axle and a slight upsweep over the front result in the frame level, when loaded, being 1 ft. 11/ ins. This dimension, of course, is as small as can reasonably be expected, and by virtue Of the provision made for a clear platform line the overall height of the vehicle, when fitted with an enclosed body, is rendered relatively low. A few dimensions of the chassis may not be out of place here. With wheelbase and track measurements of 15 ft. 6 ins. and 5 ft. 101 ins, respectively, the overall length of the chassis works out at 22 ft. 8 ins, and the
overall width, measured over the wing tips, 7 ft. 4 ins. With an overhang of 5 ft. 7 ins, from the centre line of the rear axle to the end of the frame, the body space ,(i.e., from the dash to the end of'the frame) Is 17 ft. 11 ins., and the width of the frame at the rear 3 ft. 31 ins. The ground clearance up to the rear axle is 101 ins, and under the axle casing itself 8 ins.
Dealing now with the power unit. The engine, dutch and gearbox are formed unitwise, the wholehole assembly being mounted in the chassis at three points, all of which are of a rigid nature; the forward one, however, being mounted in a trunnion bearing, permits the chassis to twist without passing any stress on to the crankcase. Each of the six cylinders has a bore of 82 mm., and with a piston stroke of 120 mm. they provide a total piston-swept volume of 3,800 c.c. Although rated at 25 h.p. the unit actually delivers 54 b.h.p. at 2,000 r.p.m. and 72 b.h.p. at 3,000 r.p.m. The pistons are of cast-iron and the connecting rods are of duralumin.
The cylinders are formed in a monobloc casting which is attached to the crankcase by a large number B34
of substantial bolts. The upper face of the cylinderblock is surmounted by a detachable head which, of course, carries the valves. Four bearings are used for carrying the crankshaft all being fed with oil from a gear-type pump submerged in the sump and driven by spiral gears from the rear end of the camshaft. In passing it may be mentioned that the sump has a capacity for 21 gallons of oil and the filter fitted in the base can be removed for cleaning purposes without losing any of the lubricant. Another feature of the oiling system which is worthy of note is that all the main ducts through which the lubricant is forced are either east-in pipes or passages drilled in the crankcase casting, thereby avoiding the use of loose pipes.
All the main features of the distribution (carburetter, inlet and exhaust manifolds, etc.), as well as the auxiliary drives, are housed on the near side of the unit, so' that when the chassis is fitted with " forwarddrive " everything remains quite accessible. A large box-like timing-case on the near side has two shafts emanating from its rear chef*, the upper one providing the driving media for the fan and the magneto, whilst the lower one provides the drive to the dynamo and water pump, which are in tandem. In order to provide an effective hot-spot in the induction system, the six-branch inlet manifold is bolted up to the exhaust manifold at the centres of the two pipes. The mixture is supplied to the cylinders by a vertical-type Solex carburetter, the petrol being fed to the float chamber, by means of an Autovac, from a 30-gallon tank which is slung on to the near side of the chassis. Before going on to a consideration of the transmission, mention should be made of the construction of the overheadvalve gear. The rockers are carried on a single shaft, which is supported on no fewer than seven bearing-standards.
A single-plate clutch of large size and capacity transmits the drive to a four-speed gearbox with central control. The gear ratios are as follow : 1st. 32.9 to 1; 2nd, 16.31 to 1; 3rd, 9.87 to 1, and top, 6.25 to 1 (reverse, 51.43 to 1). These ratios permit 20 m.p.h. to be obtained on second gear and 35 m.p.h. on third gear, so that when touring in hilly country, gradients requiring the use of an indirect gear can be climbed at a fast pace, without, seemingly, over-revving the engine. As might be expected, the drive is conveyed from the gearbox to the rear axle by a two-stage propeller-shaft in order to avoid any possibility of whip occurring at
high speeds. The mounting for the centrebearing is of particular interest, for the shaft is supported in a Skefko self-aligning ball race the outer cage for which is contained in a rubber-insulated yoke. HardySpicer joints are used for both ends of the secondary shaft, which is, like, the primary shaft, a tube of substantial dimensions.
The brakework next claims attention. Following modern practice the pedal applies a four-wheel system through the medium of a Dewandre servo motor. The actual layout for the control is very nicely planned, neatness being combined with effectiveness. Take the case of the installation of the servo motor, for example. The pedal rod is short and the power rod (emanating
from the rear of the servo) fits snugly up to a crossmember. The whole unit is therefore compact and does not suffer from the lost motion which results. from using long rods and -flexible shafts. Further, there is a master adjustment on the power-rod coupling to the main cross-shaft, which permits wear on the shoes to be taken up without the use of tools, a selflocking nut in wheel form taking the place of the usual turnbuckle and lock-nuts.
The chassis is suspended on setnl-elliptic springs front and rear, the latter being exceptionally long and underslung beneath the axle easing.
As we said in the earlier part of the article, the controls operate with commendable lightness; the steering is no exception. This is unquestionably aceoun:ed for by the fact that a Merles cam-and-roller reduction gear is used. Even on rough roads there is remarkably little "kick" from the wheel, whilst on normally good surfaces it remains as steady, as a rock, There are many items in the chassis which call for commendation from the point Of view of maintenance of tune. Even the grease nipples to the various items requiting lubrication on the chassis are brought into fairly convenient positions, a statement which, of course, includes the fact that very few nipples are what is generally known as underneath." .
The power unit, too, is planned on sensible
Take, for instance, the Watford. MaOleto, which IS capable of being set to within One degree of the desired position, and the easy adjustment prOvided for taking up slackness in the silent-chain drive to all the auxiliaries. The positions of the magneto, dynamo, carburetter and so on are conveniently arranged in order that the "business ends" of the instruments in question can be inspected or adjusted as occasion demands. Again, the water pump has an easily, packed gland and valve adjustment is also simple to carry out. Other notable tietails include the provision of a power take-off for a mechanical tyre pump, a simple adjustment to each individual pair of brake shoes and a sonvenient fillet spout to the fuel tank.
Details of the brake gear, adjuster and Dewandre servo.
SELF ADJUSTER,
The chassis is well equipped with wings of graceful design, a 12-volt lighting and starting set, dipping headlamps and the usual side and tall lamps, Dunlop disc wheels secured by ten studs, and twin tyres at the rear with a full equipment of 36-in. by 6-in. tyres all round, a spare being included.
. The chassis price is £68; it is British throughput.