THE SUCCESS OF A NOVEL VEHICLE.
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Details of Recent Products from the Works of Shelvoke and Drewry, Ltd., and Notes on Some of the Unusual Features of the S.D. Freighter Chassis.
MHE VEHICLE known as the S.D.
Freighter, which was first placed on the market about a year ago by Shelyoke and Diewry, Ltd., of Letchworth, can certainly claim to be one of the most novel which have yet been developed for running on ordinary roads. When we first inspected this 2-ton machine we were at once impressed by its great potentialities, and we are certainly not eurprieed at the great progress which it has already made. Municipalities throughout the country, manufacturing concerns and others who have certain classes of goods to carry and confined districts in which to operate, are recognising that this little vehicle meets a long-felt need, and its production has opened up the possibilities of using mechanical transport in spheres in which, until its arrival, real success had nut been gained. We do not suggest that it could take the place of the ordinary petrol vehicle in long-distance work; as a matter of fact, such an idea did not enter the heads of its designers, as it was built expressly for short and moderate journeys arid for local deliveries, where its peculiar features would prove parlieularly advantageous.
A Light Chassis.
• On the ton-mileage.basis it almost defies competition, for its tare weight is only 23 cwt., although it can carry a useful load of two tons apart from tha body. Consequently, its petrol consumption is low, and, fully laden, it can do
15 m.p.g. and achieve a speed of
16 m.p.h. on straight runs, and this with an engine rated at only 13.2 h.p.. It also has a very large body space as compared with its total length and wheelbase. In fact, on a wheelbase of only 11 ft., bodies up to 16 ft, long can be employed, and even then the turning circle has a radius of only 18 It4 ins. Incidentally, a vehicle with a leading space of this length has recently been built for Messrs. Groom, Daniels and Co., of Colchester, who wish to employ it -for carrying 24-ft, -lengths of timber.
• Low Loading Platiorm.
Loading and unloading are greatly facilitated by the fact that the piatiorm of the freighter is only 23 ins, above the ground, although this can be increased if necessary to Suit the needs of users who May have loading docks of a greater height.
To our mind, however, perhaps the most important feature of the whole machine IS the extreme simplicity of its control. Only one handle is required for operating the gear changes, for forward running or reverse, this handle also slowing or accelerating the engine as the changes are made, and bringing the transmissioti brake into operation as required. Actually; the forward arid reverse clutches net alternately as brakes. • A special type of epicyclic gear with four multiple dry-disc clutches is emplo§ed, and, is all the chanaes and the
reversing are effected through these olutches, no pedal-operated clutch is required. In fact, the only foot controls are a pedal brake acting on the front wheels and an accelerator device, which is merely held down by the foot, and more closely resembles the cut-out on all electric truck than the ordinary Torm of accelerator, for, as already explained, the actual accelerator' is formed by the control handle, and the only other control is the steering handle at the alher side of the driver's seat.
Tlit4 gearbox gives three speeds in. both directions, and the box cannot be injured by rough usage. •
One point which has considerably assisted in the satisfactiiry service given by this interesting little vehicle is that the load is evenly distributed over the wheels, so that it has been possible to make the springing so supple that, in spite of the .very small wheels which are employed (these being actually, for solid tyres, 20 ins, in diameter and 5 ins. wide), the vehicle will ride quite comfortably even over rough roads.
Constructional Details.
The power unit is a White engine. This, together with the gearbox, is carried transversely in the casing surrounding the driver's seat, so that they do not take up any part of the loading space, From it the drive is taken through a two-piece propeller shaft— in which the rear end of the front portion is supported in a ball bearing—La a rear axle fitted with David Brown ever
bead worm gear, and this axle allows a clearance of N ins. ceder the centre. Laminated steel joints are employed for the cerdan shaft, and the adoptioa of the two-piece construction, is a minor alteration, which haSs been: made since the vehicle was first broughteout.
Steering is on the AckermanprmcipIe, being controlled. from the eering handle through the medium era' spurwheel reduction gear and a sector.
Particular attention has been paid to the question of lubrication, whicb is practically automatic throughout All the shafts are on ball bearings, and the semi-rotating parts are made of rustless steel working in self-lubricating bushes. No greasers are fitted anywhere. The engine requires oiling once weekly, and the gearbox and rear axle once monthly, so Ural elie machine can safely be placed in the hands of an unskilled man both for driving and attention.
In traffic it has been found that the Freighter can perform delivery rounds quite as quickly as any normal machine of much more power, and it is so easily controlled that the acceleration after a traffic stop usually brings it right away from neighbouring vehicles, as no pause is required between the changes of guar.
One of our illustrations shows a recent example supplied to the Wilts. 'United Dairies, Ltd. This, it will be noted, is equipped with a runway and lifting tackle, which are capable of dealing with milk churns and heavy drums of condensed milk.
For municipal wore severet models are available. A particularly interesting one is that recently supplied to the Colombo Municipality. This is a dustcollecting vehicle with wood-slatted canvas covers, each of which is secured by a rope twisted once round a cleat. Apart from the question of the chassis, there are some interesting points about the body. This is of the end-tipping type, equipped with a single-ram hydraulic gear built by the makers of the chassis, and so arranged that as the 'body is lifted it is pushed back slightly so that when it is at its highest tipping angle the rear end of the body is quite close to the ground. When it drops a curved bracket at each side comes into contact
with a roller on the frame, and further movement forces the body forward to its original position.
The tailboard is hinged at the top, and, normally, is locked by a simple latch, which can be eontrolled from the ,friver's cab. Wire ropes from brackets on' this tailboard' pass over pulleys attached to the body, and are then con. nected to the chassis frame in such a manner that-as the 'body tips the tailboardeis 'autcrmalically lifted.
A third useful type of machine is that equipped for detachable platforms, which also is illustrated, together with the platform in position and separate.
The body consists of a railway-type flat mounted on faux metal supports, whilst on the chassis frame is a series of rollers, these rollers engaging with a runway on the underside of the body or flat, the front portion of which is. sloped upwards. On the chassis are also the necessary buffer gear and locking catches, so that the flats are cheap to construct, as they carry the minimum of parts.
Loading and unloading these flats on to and off the chassis are wonderfully simple operations, and depend entirely upon their inertia. Assuming that the flat is loaded and resting on the ground, the chassis is backed until the rollers , at the end engage with the forward end of the runway, which is splayed out to assist this. The maximum lift provided for is approximately 6 ins., and the chaseis being unladen is, of course, at its maximnin height from the ground, in which case the rear rollers are be
tween 1 in. and .^2 ins, below the upper end of the ramp. As the .chassis is driven backwards, its . springs become . compressed until the front end of the platform is lifted from the ground. The rearward motion is continued until about two-thirds of the body is over the chassis, when the rear endcommences to lift. The continued backward movement causes the platform to come right forward, where it is held by the automatic latch.
To unload the platform the latch is disengaged and the chassis quickly accelerated, when it leaves the platform with its load.