Improved Scammell Six-wheeler Conversions
Page 37
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FOR the forthcoming year, several important improve! ments will be incorporated by G. Scammell and Nephew, Ltd., Fashion Street, London, E.1, in its conversions of standard four-wheeled chassis to six-wheelers of approximately double the load capacity.
A representative example; which will be exhibited as a chassis at the Commercial Motor Show in November, is provided by he Dodge 4-tonner, converted for use as a 7-S-tonner, the rear portion of which is illustrated above.
Following in principle the design that has become well known in connection with recent Scammell conversions, the latest bogie and the method of mounting it and of extending the chassis frame are easily understood from the picture.
Riveted to the longitudinals, at the bverlap, is a pair of sturdy channel cross-members, placed back to back and about 6 ins. apart. To these are bolted the two brackets which carry the balance-beam cross-shaft, their positions being just within the frame side members.
The back ends of the original driving-axle semi-elliptic springs are linked to the front ends of the balancers, which• are just below them, whilst the rear ends of the beams, which carry the trailing-wheel stub axles, are shackled to an inverted semi-elliptic transverse spring, itself mounted by a central universally pivoted bracket bolted below the hinder of the two cross members. This channel is webbed at the point of attachment and has a lower flange of extra width ; thus it is well equipped to withstand the additional loading to which it is subjected.
It is noteworthy that the Timken roller be.a7ings, upon which the balancers rock, are of greater dimensions than those used hitherto, whilst the beams and brackets have also been increased in strength. In this connection it is of importance that the effective distances from the beam rocking centre are proportioned so as to impose the greater pressure upon the driving wheel for tractive purposes, and to compensate for the load taken by the transverse spring.
On this Dodge chassis, no alteration has been made to the standard Lockheed brake system, but a Dewandre servo valve has been connected up to the pedal, and a pair of vacuum cylinders provided, which apply shoes in the trailing-wheel drums by flexible encased cables. These shoes, incidentally, have frictional surfaces each measuring 16 ins. by 3 ins. On this long-wheelbase Dodge the body space afforded by the extended frame is 18 ft. 6 ins, long, and the price of carrying out the conversion, when heavy-duty tyres are used on the bogie wheels, is £165.
A feature of the additional mechanism is its small number of working parts and the generally clean and workmanlike design of the whole layout. Adequate provision is made for lubrication, grease nipples being provided for all bearing surfaces.