A Useful Three-wheeled Electric Tractor.
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TN the many spheres of transport in which it is employed the industrial electric machine, in its truck and tractor forms, is giving good service to many users. It is a highly 'efficient little unit, which is economical to operate, and it is able to tackle certain transport and haulage tasks which could not so. readily be undertaken by any other form of power-propelled outfit. Little wonder, then, that its merits have received tangible recognition from many important users, particularly in cases where the nature of
• the work undertaken necessitates the use of transport media between the various departments of a works , or factory.
In some instances the industrial electric tractor has advantages over a machine of the same type which is built to carry loads, particularly where delays occur in effecting loading and unloading operations and waiting time is, as a consequence, often of long duration. With an electric tractor the loss of time on non-remunerative work is negligible, for so soon as it has hauled the trailer, or trailers, which carry the load, it can be put to profitable use in other directions.
A typical industrial tractor of this type is the Slingsby-Automatic, a use for which is' indicated in the accompanying illustration, in which it is to be sten hauling .ft big load of various Slingsby products. Messrs. H. C.
Slingsby, of Ningsway, London, W.C.2, tell us that the outfit is used for delivering goods in the London area, as well as for hauling many of the firm's products to the various exhibitions which are held in different parts of the country and at which they are to be displayed.
As will be seen from the picture, the Slingsby-Automatic is a three-wheeled tractor. It incorporates a 'number of interesting features, and is provided with a 3i h.p. Automatic motor, which is spring-suspended, thus reducing the
effects of vibration on the unit. The driving axle is of the full-floating type and the drive is effected by a singlereduction steel worm and a bronze gearwheel. The metal drum-controller, which has large contact plates and provides three speeds in both the forward and reverse directions, is mounted so as to permit direct operation by the controller handle, thus overcoming any lost motion which occurs when linkage is used. An important safety feature is the interlocking device which prevents the release of the brake and the application of the power until the operator
has taken up his position in the seat.
The battery box is so arranged that the batteries can readily be removed either from, above or at the side. The batteries are well secured to their tray by holding-straps and the tray is held .in position by anchors which prevent movement of them. The frame of the tractor is built of 4-in, channels of Isection and it is supported on the rear axle by two heavy steel-coil springs. Bumper plates are fitted both fore and aft, in order to protect the machine from damage should collision occur, The standard model of the Slingsby tractor is equipped with wheels of 16-in, diameter, but 20-in. wheels can be provided,The wheels are shod with solid-rubber tyres.
. The overall dimensions of the tractor are as follow.: Length, 6 ft.; width, 3 ft. 4 ins.; height, 4 ft. 4i ins. Its wheelbase is 3 ft. Sf ins, and its track 2 ft. 6 ins. The turning radius of the tractor is 4 ft. 2 ins., thus enabling it to be turned in very restricted areas. The weight of the tractor when Edison batteries are employed is 2,550 lb., but When lead batteries are used it is increased to 2,750' lb. The normal drawbar pull of the machine is 600 lb., but its . ultimate drawbar pull is 1,600 lb.
The tractor is built on robust lines throughout and has already proved its worth in many directions.