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SIMPLIFYING CHASSIS CONSTRUCTION.

20th April 1926, Page 21
20th April 1926
Page 21
Page 22
Page 21, 20th April 1926 — SIMPLIFYING CHASSIS CONSTRUCTION.
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Some Details of a Revolutionary Method of Building which Halves the Weight and Substantially Reduces the Cost.

ATUCH attention has . been devoted _LVIduring the past few years to the design and construction of chassis Which, whilst being light, will also be of sufficient strength to stand up to the . hardest work which they are called upon to perform.

Undoubtedly, lightness is one of the most important factors in the efficient /1111 tli ng of the commercial vehicle, -whether it be intended for passengers or goods. Unnecessary weight is really a dead loss, for it reduces both the useful carrying capacity of a vehicle and the ton-mileage figures, and means that quite a large amount of unnecessary work is performed, whilst fuel, oil and rubber are wasted in transporting non-paying loads. Providing the factor of safety Is satisfactory and that due provision is made for a long-wearing life, then the lighter a vehicle can be designed for its load, capacity, the nearer do we approach to the greatest possible efficiency. So far as ordinary construction is conterned, it 'would appear that we have -reached a stage of design which, with the materials at present available, cannot permit much further reduction without danger, and with the commercial vehicle it must always be remembered that safety is the most important factor of all, and particularly so is this the case when valuable lives may be dependent upon the satisfactory operation of a vehicle and its response to the driver's control.

It would appear, therefore, that further large reductions in weight can only be obtained by a complete altera _. tion in the methods of construction, and this has actually been effected by M. Eugene Fejes, a well-known Hungarian engineer, who was for many years the chief engineer at the Westinghouse works at La Havre.

His methods are not an inventor's freak, but the result Of years of painstaking study, the first chassis built by the Fejes method being dated about 1920, whilst the actual model which is available for inspection in England is one of numereus types which have been tested since 1922, both by the constructor and by the Hungarian Government. Chassis similar to this are being employed by the Hungarian Post Office for 1-ton loads, whilst 30-ewt. and 3-ton chassis have lately been built for the Hungarian War Office.

The extraordinary point about all these chassis is their weight, which, in the lighter models, is about half that of a chassis of ordinary construction intended for the same loads, whilst in the heavier models the weight reduction is even greater. The 1-ton lorry has a chassis weight of between 8 cwt. and 10 cwt., the 30-cwt. model weighs slightly over 12 cwt., and it is claimed that 'the weight of the 3-tormer can be kept as low as 15 cwt., although this is a claim we would like to see substantiated.

Although most unusual, the constructional methods employed are neither complicated nor difficult to understand. The material used throughout the chassis (of course, with the exception of shifts, gearing, front axle and a few other details) is black sheet-iron, varying from 1 mm. to 2.5 mm. in thickness. This material is pressed into suitable shapes, cut and welded, the welding being done at lips or flanges which are so positioned that the welds are not unduly stressed. No complicated forms are employed, so that not only are the press operations of the most simple nature, but as there is little distortion of the metal its original strength is to a great measure retained.

The tensile strength of the material, is between 12 tons and 20 tons per sq. in., and the price works out at roughly 130 per ton. In the case of the 1-ton chassis about 5 cwt. is required.

So far as the frame is concerned, the side members are built up from four strips, suitably shaped and welded to form hollow girders which are reinforced where necessary by internal webs, or bushed by small tubes for such parts as the spring shackles. The cross-members and the sub-frame for the engine and gearbox are built up in the same manner and are welded to the side members, no rivets being employed throughout.

A similar method of construction is employed for the gearbox. At each end are two vertical plates divided horizontally and welded into box form, constituting the housings for the ball races, extension pieces formed in one with the upper portions acting as bearer arms. The remainder of the gearbox is practically orthodox.

For the back axle sheet-metal 1 mm.in thickness is mostly employed. Those

portions which are subjected to severe stresses ore, however, suitably strength ened by the employment of bracing rings which also serve to carry the differential bearings. The axle is of the full-floating type with robust driving shafts. Most unusual construction is also employed in the engine. This has a bore

and stroke of 60 mm. and 110 mm. re

spectively, giving a capacity of 1,244 c.c. The overhead 'valves are operated by push rods from a single camshaft 80 arranged that, when desired, side-valve cylinders can be employed. The cylinders are actually made of drawn-steel tubing which is rolled internally to limits of .0001 in., this operation taking only five minutes. The four are then assembled on mandrils, and the water jackets, inlet and exhaust manifolds and sparking-plug sockets are welded into place, the joints being made in a special manner which allows expansion or contraction. The cylinder walls have a thickness of 2.5 ram., and this enables most adequate cooling to be effected, permitting a higher compression ratio and an improved power output. The cylinder heads are screwed on and welded, the base of the cylinders also being secured by welding. The lightness of the block and the ease with which it may be detached have obviated the need for detachable heads. It might be thought that a crankcase built ,up from pressings would not be -rigid. This is far from being the case, and it is actually claimed that the method employed provides such rigidity that the balancing of the crankshaft is not of extreme importance, as vibrations are damped out.

(Top) The upper portion of the remarkable o.h.v. engine, which has drawntube cylinders, welded jackets and flanges, and a we crankcase. (Centre) Showing the method of building-up the rear axle. (Bottom) Welded sheet-metal construction as applied to the

gearbox.

The engine-bearer arms also act as supports for the main bearings. They are formed as box-section girders and extend right through the crankcase. They are also continued upwards and Penetrate through slots formedin the face plate which acts as the top of the crankcase and to which the -cylinders are bolted. The employment :of stout bolts at certain points prevents distortion during welding by the absorption of heat in the mass of metal. Thin sheet-metal is also employed for the timing case, a light pressing above this forming the fan bracket. The power is transmitted by a multiple-disc clutch of the metal-tometal type, a metal-disc universal joint being provided between the clutch and the gearbox, which, in the case of the chassis in this country, is separately mounted, but it is just as easy for the Fries system to be applied to unit construction. It is claimed that one man can do all the welding work on a chassis in approximately 30 hours, but with a big production, the use of jigs and electric welding would considerably reduce this time, even to so little as five man-hours. This is the main reason why a saving in price of from 25 to 30 per cent. over ordinary constructional methods can be made. The reduction in weight has resulted in an increase in the power-weight ratio. Higher gears may he utilized and fuel consvmption proportionately decreased. We consider this method of construction a most interesting one, which tire douhtedly possesses many potentialities, and we hope to see some of the heavier models arrive in this ceuntry so that they can be given a thorough test. We understand that arrangements are being made for producing in Great Britain chassis built by this process.


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