A Four-wheel-drive 6-tonner Weighing Under 2 Tons
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The Use of a Spicer Lattice-girder Body, Affording an Adequately Strong Structure, Enables the Unladen Weight to be Kept Within the 22-ton Limit
THE interesting structure incorpor ated in the body of the platform lorry shown in the accompanying illustrations was evolved by Spicers, Ltd., Eaton Street, London, S.E.1, to avoid exceeding the 2f-ton weight limit, in executing an order for a Bedford machine equipped with the Unipower bogie. The vehicle was recently supplied to Broad and Co., Ltd., a concern of building-material specialists, and is used regularly for carrying 6-ton loads, mainly of bricks or cement.
The platform and its framework scale 3 cwt. 68 lb., and the cab weighs 1 cwt. 84 lb., making a. total for the complete body of 5 cwt. 40 lb. The floor measures 11 ft. 6 ins. by 6 ft. Gins. and is built of five-ply wood.
The framework is composed entirely of 1-in, by i-in. and I-in, by i-in. angle iron, and incorporates no fewer than 108 triangles, practically every member being in compression. Every joint is welded, except where the extremities of the cross-bearer girder are tied to the outer framing, bolts being used for this purpose. There are seven crossbearers, attached to each 'other by horizontal and diagonal members.
The simplicity of the method of attachment to the chassis frame is noteworthy. The extended ends of the vertical members are forged and threaded to form studs, carrying crosspieces as shown in the drawing.
To stiffen up the main chassis members they have been shrouded by straight 7i-in. channels. These are carried from the back of the cab to the end of the frame, and bridge the wheel arches, the upper sides of the channels being cut away at this point.
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To these channels is attached the Unipower bogie (described in The Commercial Motor on October 27, 1933), which, it will be remembered, incorporates a two-speed gearbox and drives through both axles. Its layout, briefly, is this : the propeller shaft transmits the power, through either of two trains of gears and a differential, to two short shafts provided with universal joints, which convey it through further differentials to the fully floating axle shafts.
Rzeppa constant-vel6city universal joints are used in tips main propeller shaft and stub shafts. The two wheel axles are carried at the ends of two pairs of centrally mounted inverted semi-elliptic springs, one spring being placed above the other on each side.
As the gearbox is rigidly fixed to the frame, the minimum clearance is required above it and the unsprung weight is low. The maker is universal Power Drives, Ltd., Aintree Road, Perivale, Middlesex.
The low weight of the cab has been obtained by the wide use of plywood and aluminium panelling, and it is of interest to note that the two doors together weigh no more than the windscreen. It is a standard product of Spicer% Ltd., and this concern informs us that it intends also to put into production this interesting lattice' girder body.