DEVELOPMENTS IN REFUSE-COLLECTING.
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Some Notes Upon a Particularly Interesting Vehicle Designed Expressly for Journeys of Moderate Length. and for Work Where a Low Load Line is of Vital Importance.
FOR NEARLY a year we have been following with great interest the development of a peculiar type of vehicle known as the S.D. Freighter, which has been developed for short and moderate-journey work, and particularly for that involving frequent stops and manoeuvring in narrow thoroughfares. Apart from this, it should prove of ealaeme value if employed in connection with dock work, and anywhere else -where its features of large platform area for abort' overall length and a loading platform 1 ft. 10 ins, from the ground would prove advantageous.
The load capacity of the new vehicle is 2 tons, and the dimensions of its platform are 10 it. by 5 ft., this width being capable of extension up to 6 ft. 6 ins. One of our illustrations shows it compared with a normal 2-ton lorry. In its general appearanoe the machine closely rasembles, in a magnified form, what is known as a platform truck, but that it is more than this is shown by the fact that it has travelled from London to Birmingham and back at an average speed of 124 m.p.h. on a fuel consumption of 1 gallon per 15 miles, and this with a full 2-ton load.
The. feature which proves most strikingto the casual observer, and perhaps to others, is the simplicity of the controls. 'these consist of a handle at the right for steering and a combined gear and brake lever, resembling a tram control, at the left, On a raised platform, upon which the feet of the driver rest, are a bell-push and an automatic throttle cut-out, which moot be 'kept depressed in order to permit the automatic throttle to operate.
The driver'e seat forms a recess hi the casing surrounding the transversely positioned engine and transmission gearing; a certain amount of protection is afforded him by a sheetsteel dash.
So compact is the driving gear that it is difficult to believe that, the vehicle is propelled by a petrol engine, and.,yet this unit is rendered remarkably accessible by taking off panels at the front and side a the casing. The bore and stroke are 73 ram. and 130 mm. respectively. With four cylinders this gives a rating of only 12 h.p., as compared with the 30 h.p. engine usually employed on a 2-tanner. The cooling water is pump-circulated through a gilled tubular radiator occupying the left side of the trans
mission gearing. •
The gearing is of a most unusual type. It gives three speeds in each direction, the changes being effected through the medium of multiple dry-plate clutches. The gearing is of the epicyclie type, with the pinions in constant mesh.
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The drive from. the engine is through a flexible spring plate, On the main gearbox shaft are two clutches, one at each end. With that at the farther end engaged, first speed is obtained; when that at the flywheel end is engaged, it gives second speed; when both are clutched, top speed, or direct drive, is obtained. The gearbox main shaft if3 set across the chassis, and a second shaft is set longitudinally; this shaft also bears two clutches, for providing forward and reveres motion.
The forward dutch runs in one diregtion and the reverse Clutch in the other, this effect being obtained by driving the clutches one from one side ol a bevel pinion in the gearbox and the other from the opposite side of this pinion. As both these clutches rotate constantly while the vehicle is in motion, it is obvious that a braking effect is provided by engaging-both simultaneously. This braking action takes place in either direction. If the vehicle be running forward, then the reverse clutch acts as a brake; if it be running backward, then the forward clutch performs the same duty. The one control handle thus operates all three speeds and the transmission brake. Apart from this, it gives automatic throttle control.
Immediately the control, handle is moved in order to change speed, the engine throttle is closed to its slow running position until the next speed is brought into action the throttle is then opened automatically, and the vehicle picks up to its maximum speed, which is controlled by a governor. Continuing with the transmission, the drive to the propeller shaft is taken from the forward or reverse clutches, as the case may be, through a laminated steel joint; a similar joint is provided at the rear end of the propeller shaft, and the final drive, to the rear wheels is by overhead worm with a ratio of 3.8 to I, a differential being embodied.
The wheels are 20 ins, diameter and run on ball bearings. In addition to the other controls, there is a. brake pedal, which operates expanding shoes n the front-wheel drums. When desired, an auxiliary drive can be provided on the gearbox for driving the hydraulic pump for a tipping gear. This interesting vehicle incorporates some 200 less parts than the average 2-tonner, and its four wheels are interchangeable. It appears almost foolproof, is very stoutly built of the finest materials, and yet weighs only 21 cwt.
Both engine and gearbox are mounted on a single, stout deep-section steel casting, so that they are always in align rnent.
Only three sizes of bushes are used in the chassis. These .are made of compressed fabric, graphite and oil, and are used only for those shafts which do not revolve. The material of these shafts is c....5-ton rustless steel, hardened and ground. Every rotating abaft is carried on ball races, of which there are some 30 in the chassis.
These run in grease reservoirs, except in places where oil is constantly present, as in the .gearbox and back axle. During a short test "rim, which We Made with a load of two tons and five passengers in addition, wewere Very agree ably impressed with the speed and abilities of the machine, and noted with interest that the springing is so good that smooth running was obtained even when -passing at fair speed aver a road in which potholes abounded. The control is simplicity itself, and the vehicle can easily turn in a 21-ft. circle,
. The price of the chassis, complete with flat platform body,. is £425, and the makers are Shelvoke and Drewry, Ltd., • Letchworth, Herts.