• A ONE-TONNER WITH A CHAIN-TRACK DRIVE.
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A New Type of Light Vehicle which can be Employed on Loose, Soft, or Irregular Surfaces.
MHE EXPERIENCE of the war showed, contrary to all previously formed opinions, that instead of the motor vehicle being rendered helpless in the face of rough, tumbled, uneven and broken welled, it could be so equipped with chain tracks that it could actually go where horsed vehicles could not be employed., The Caterpillars and the chain-track machines, including that wonderful conception, theTank, made elaort work of the hazards of " No-man's Land," and the knowledge then gained has not been allowed to be wasted, but has been utilized in the development of vehicles which_ can render useful service in civilian life. Overseas, where there is only scattered population, roads, however eminently desirable, cannot be made, except at an expense which could not be justified far many years to come. Hence, because of the dearth Of hardsurfaced roads-and of the wish to make use of the motor engine as a means of propulsion for"vehieles employed in civilian work, a certain amount: of attention has been paid to the development of the track-laying machine, and energetic efforts have been put forward in order that the difficulties which are presented by the eubetitution of an endless track in -place of the rolling wheel, shall be overcome. .
The initial advantage offered by the track layer is, of course, .the• increased area in contact with the ground and the cc/meg-tient reduction of pressure per
square inch. This pressure naturally depends upon the nature of the ground : when it is very soft, the pressure falls
as IOW as 5e lb. per square inch; on herd ground it ie still only about 17 lb. per square inch. A second great advantage is the prevention of .skidding or side slipping—the former being a slip in the direction of the travel of the vehicle and the latter a lateral slip.
The disadvantages introduced by the track layer have hitherto been noise and rapid Wear of the joints in the teack, but these are being entirely oyercome. Taking, for example, the Guy-Headless one-ton chassis,which is Made by Guy Motors, Ltd., by arrangement • with Roadless Traction, La, it ,iS. claimed that the vehicle is quiet and smooth in its running, beeanse the sprockets and idler wheele are all rubber tyred, whilst the special type of track introduced by Roadle,ss Traction, Ltd., is such a different proposition from that lallieh was employed for the Tanks, ,every joint being lubricated and protected, that wear is reduced to a reasonable minimum. Moreover, the claim for this type of track is its longitudinal flexibility, which pormits the vehicle tosteer in a curve without the track screwing itself round upon the road surface. The Guy-Roadless chassis has been dealt with by us in detail, and may with advantage be more fully described here. The chassis is constructed by Guy Motors, Ltd., and is delivered to Road. less Traction, ma., on four wheels, the substitution of the tracks for the wheels 'being effected at the Hounslow works of the latter company. The power unit embodied in the chassis is the 18 h.p. four-cylindered engine, with clutch, gearbox and controls, which is employed in the 25-wt. Guy commercial chassis. This is a very effielentnnit, the cylinders being 88 mm. in the bore and the' piston stroke 120 mm. The valves are inclined and are operated from the camshaft, through rocker arms, so that the combustion. space closely approaches the ideal of thereeent day, whilst extreme accessibility is afforded to the yalvertap pets. The cylinder head is detachable and has outside water connections to the cooling epees, so that it is impossible for water to leak into the cylinders. The power developed by this engine, as we have already recorded, is 22* h.p. at 1,000 r.p.m. and 33 h.p. at 2,000 r.p.m. A single-plate clutch transmits the power to a four-speed gearbox. Whilst the vehicle could accomplish a very fair
turn of speed, from 12 to 15 m.p.h. is recommended for the type of drive. The back axle is driven by an overhead worm through a bevel-type differential. To each axle shaft is attached a driving sprocket, each chain track being carried over an idler wheel in front and two weight-carrying wheels in between. The sprockets and idlers are normally held clear of the ground, the latter being so mounted that they are free to rise When an unusual obstacle is met.
The chain tracks consist of universally jointed stamped-steel links and plates. Each joint consists of a hardened and pound pin of special steel working in a hardened and ground bush, also of steel. The outer diameter of the bush is partly spherical, allowing the plates and links to have a universal movement and the track to conform to all irregularities and to the camber of the road or surface.
This universal movement of the joints prevents he pins from getting "across corners" through any malalignmenti of the tracks when coming on to the sprockets. Each chain joint is lubricated from a reservoir of oil in the link, and is protected against the intrusion of mud, dust or water by a shrouded seal ring of special patented design. The wary in which these chain tracks accommodate themselves to unevenness of surfs& is marvellous, whilst the grip they get on ground which looks impassable to motor traffic is a testimony to the value of inereaelg the area of surface contact. That, there is no difficulty in steeriag is shown by one of our illustrations depicting a vehicle describing a figure of eight at a good, speed, whilst the markings in the foreground show that there i,s no sideways twisting of the track as it takes up its direction of travel.