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An Epicyclic-geared " Three-tonner."

2nd December 1909
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Page 4, 2nd December 1909 — An Epicyclic-geared " Three-tonner."
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A Description of the First Example of an Interesting Type of Lorry which has now Completed a Two Years' Test.

There are several very good reasons why the particular chassis, which we arc about to describe, possesses characteristics which are hound to be of especial interest both to the user and to the manufacturer of commercialmotor vehicles. It is, primarily, at least as unusual as it is desirable to submit a new model, whether it be ultimately destined to perform service as a touring-car or as a commercial-vehicle, to a road-test in actual service of so long a duration as two years, before it is definitely placed upon the market. .1 feature of this model, which is no less noteworthy than the far-reaching trials to which it has been subjected, is the unconventional nature of the whole design.

Intended as a standard three-ton model, Joseph Baker and Sons, Ltd., the well-known manufacturing engineers, of Willesden Junction, about two years ago, designed and produced the first of a new type of commercial

vehicle. Previous to this development, considerable success had attended the introduction, by this maker, of a patented form of epicyclic speed-reduction gear. which they had found extensive opportunity to embody in various classes of electric-motor-driven machines, most of which were specialities built and designed expressly for the baking trade. This form of gear yielded such remarkably-satisfactory results from the point of view of low maintenance, that it is not surprising, at a time when commercial motor vehicle change-speed mechanism was a particularly troublesome problem, that its application to automobile purposes was carefully considered by its de

signers. It seemed to offer the necessary qualities of being foolproof in operation, of quietness, of great durability and of high efficiency. From the simple form of epicyclic reduction gear to the more-complex types of two-speed and three-speed change gears was a practicable development, prompted by careful design. It is interesting here to record that those who have been responsible for the development of Baker's gear, in the course of conversation, profess a profound dislike, from a mechanical point of view, to anything in the nature of a helical or worm gear.

The decision, to embody this interesting gear in a motor-vehicle chassis, evidently brought with it a desire to improve at the same time, upon the more-conventional details of the usual type of heavy petrol-propelled machine. The eventual result was the sturdy and compact-looking machine n hick we show by the reproduction of a photograph on the next page. This first vehicle was sufficiently satisfactory, on the whole, to warrant the careful consideration of its makers as to whether the available market, at that date, for such a vehicle offered possibilities of commercially-remunerative development. Some 60 years of successful 'business in the production of numerous classes of specialized machinery, from sugarcane mills, and soap and jam-mixers, to every kind of baker's appliance, had rendered Joseph Baker and Sons cautious. The success of this new machine. the first of a class of production which was, in a way, new to its maker was not permitted. unreservedly. to suggest an immediate ex

ploitation of this class of business. After very mature consideration, and the careful weighing of pros and cons, the management decided that it would not be to the interests of the company to engage in the search for a market, whose extent, only those few years ago, was largely a matter of conjecture. It was, therefore, decided, as the wiser course to pursue, to allow a reasonable period to elapse, in order that the demand for such machines might present more consistent features, and, in the meantime, to subject the pioneer model to a vigorous and prolonged test under normal working conditions, the while that improvements and minor alterations might be conveniently carried out, as the need for them became evident.

• Now, after two years of this lorry's, service for the factory, the design has been thoroughly "tried out," and, meanwhile, the demand for such machines has grown beyond all manner of prophecy. It is not beyond the range of possibility, therefore, that, before long, another all-British mode/ of unconventional design may be added to the gradually-lengthening list of successful home-built commercial-motor vehicles.

It will be noticed, upon inspection of certain of the illustrations herewith, that the method, so much in evidence during the recently-concluded French industrial-vehicle trials, of placing the

immediately over the engine and gearbox, has been adopted, with the result that, for a three-ton machine, the overall length of the frame is conveniently small. An additional factor in the shortening of the machine has been secured by the

adoption of a horizontal engine. The juxtaposition of this unit and of the epicyclie-gearcase is clearly shown in a detail photograph which we reproduce, and which was taken with the driver's footboards removed. The engine is a stiffly-constructed twin-cylinder horizontal motor, with the cylinders opposed and placed transversely across the chassis. An unusual proportion has been adopted for the bore and stroke, the former of which is 5 in. and the latter 4-1. in. At 800 revolutions, the normal speed, this engine gives 16 b.h.p. The valve mechanism is operated, much as in the SerpaHet steam engine, by a camshaft, which is gear driven directly over the crankshaft. This camshaft is constructed to slide laterally with regard to the engine, and its travel is, if need be, controlled by a centrifugal governor. A heavy flywheel, of 18 in. diameter, accommodates, in the usual way, a large leather-lined cone clutch of ample proportions. The engine ignition is on the well-tried low-tensionmagneto system, and the small magneto generator for this installation is placed conveniently over the crankchamber and in a very accessible position, as shown in the adjoining view.

Noteworthy as are many of the other details of this machine, the chief interest, from the point of view of the user, undoubtedly centres round the gearbox, which may fairly be de scribed as foolproof. We are told that, so satisfactory has the running of this unit on the trial chassis been, that no hesitation will be felt in offering a very high guarantee of efficiency over a period of years. Excellent workmanship and careful design have yielded their inevitable result. During the past two years, the internal anatomy of the gearbox lia.s suffered no derangement, and its depreciation has been practically nil. Other than the relining of the brake bands, which control the outer gear-rings of the epicyclic trains, no replacement of moment has been necessary. Such a result as this is worthy of considerable attention, and this, in combination with the gear's characteristics, to which we

have already referred, of silence, and immunity from damage, at the 'lands of careless or inefficient drivers, should do ranch to forward the claims of the epicyclic gear, per se, to be regarded as a suitable component of even the

heavier types of petrol-engined industrial vehicles.

Examination of the sectional drawing, which we reproduce on page 256, clearly reveals the compact arrangement that has been adopted for the whole gearbox, uhich contains four separate trains of epicyclie gears, which give three forward speeds and a reverse. Looking at the right-band sectional view, and reading from left. to right, the groups of gears are arranged as follow : reverse, 4 m.p.h.; 1st speed forward, 6.5 m.p.h. ; 2nd speed forward, 12 m.p.h.; and top speed of 16 m.p.h. The gearbox encloses the planetary-gear cage, which is arranged efficiently to lubricate the

hole of the internal gear. The various pairs of planet wheels arc carried on hollow spindles mounted in the cage in the usual way. The internal-toothed gear-rings a register in machined grooves on the inner surface of the gearbox, and, when they are not held by the Itrake bands, they are therefore revolving in these grooves as bearings. Concentric with these grooves, others, of larger diameter, locate the band brakes. These brakes are operated by a neat arrangement of eccentric tightening rods, which are driven from a rotating shaft which, in the present instance, is controlled, through intermediate connections, by an auxiliary wheel mounted immediately below the steering wheel.

From this gearbox, the drive is taken to a stiffly-constructed bevelgeared live axle which embodies mu straight-tooth differential gear. Powerful countershaft and rear-wheel brakes are provided and are operated by font-pedal and hand-lever respectively. The robust design of main frame and the careful radial linking of the back axle are other features which call for mention. The road wheels are of 34 in. diameter, and the back springs are no less than 53 in. long. The tare weight of the complete machine, as illustrated, is 2 tons 10 cwt.

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