A New Idea in Tractor Design.
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An Armoured Internal,-combustion-engined Machine Which Cannot Become Strained by Operation Over Uneven Ground.
Mr. William Ashbee Tritton, the managing director -of Wm. Foster and Co., Ltd., of the Wellington Foundry, Lincoln, is not content with setting—so far as spring-suspension systems are concerned—the pace amongst steam-tractor builders: he has now "gone one .better than the previous best" amongst tractors propelled by internal-combustion engines. The new Foster spring-suspension system, by which system the lateral stability of a tractor is assured, was described in our issue of the 24th June last, and since that date more than one steamtractor builder have sought to improve the springing of their machines. Of this, public evidence will soon be given, probably, at Liverpool.
One of Mr. Tritton's latest ideas in the tractor line is embodied in a specification which has recently been completed for a British patent, and it is from that specification that we have worked up the accompanying diagram. The improvement consists in the substitution of a cylindrical shell for the more-usual form of frame, and„ with in the shell, the engine and transmission gearing are enclosed and protected. The common form of frame for a, motor tractor consists of two longitudinal members which are carried over the axles by means of springs, and these side members are generally connected together by two or more transverse girders which carry the machinery. Such a form of construction is quite good for a tractor or vehicle which is to be run on rails, or on any other form of even track, but, when employed on common roads, the frame of a machine is liable to become twisted or otherwise strained, and the strains will most likely be transmitted to the engine and gearing. Amongst the chief advantages that may rightly he claimed for the " shell " form of construction are: the prevention of undue strains on the working parts ; the protection of all those parts from dust and dirt; sti Ness in proportion to the weight of ii Aerial used in construction ; lowness of the centre of gravity of the ivlu le structure in pro
portion to the power developed. These are advantages which should appeal strongly to the Military authorities, and also to Colonial users. We hope that Mr. Tritton will lose no time to demonstrate the practical value of his invention.
The shell, or cylindrical frame, according to the specification under notice, is carried on two axles by easy-riding springs. One of the axles is of the steering type ; the other may -either be a live axle, with a differential gear, or a dead axle, on the ends of which the driving wheels are loosely mounted. A drawbar bracket (A) is secured to the after-end of the shell, awl to this bracket the back axle is anchored by two stout radius rods (B), which transmit the tractive effort of the wheels directto the draw bar. Inside the shell, and moimted on suitable bearers, is an internalcombustion engine (C), from which the power is transmitted, firstly through a bevel-wheel reversing gear (D) and change-speed mechanism (E), then by a chain (F) to a transverse shaft (G), and, finally, by means of a pair of spur gears (H) to a differential back axle. The differential gear could, of course, be mounted on the transverse shaft (G), in which case each of the rear wheels would be driven from the transverse shaft by a separate pair of gear wheels. The diagram has been prepared simply to illustrate the general form of construction advocated by the inventor, and, for the sake of simplicity, the usual friction clutch, differential gear, etc., have been omitted.
The forward end of the shell is closed by a suitable radiator (K), and a fan is also provided in the design. The silencer may conveniently take the form of a funnel, and this would give the tractor something of the appearance of a steamer. Access to the engine may be obtained through doors in the top and sides of the shell, and the fuel and water tanks may' be slung underneath the shell. The whole arrangement impresses us as being a particularly happy one, and Mr. Tritton is to be congratulated on the evolution of 80 simple and practical a design. We were first given some idea of this design by Mr. Tritton, in confidence of course, shortly after the War-Department trials for tractors, in March of last
year. We have respected Mr. Tritton's confidences of last year, but we
sure that he will not mind the present notes on a specification which is now public property. We look forward to some interesting results from the first machine which will be built. to the design outlined herewith, and which is now in hand.