AN AMERICAN SIX-WHEEL-DRIVEN CHASSIS.
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Brief Particulars of an Interesting Type of Rigid-frame SixWheeler Designed for Cross-country and Rough-road Service.
A. NEW 7i-ton rigid-frame six wheeler, driving through all its wheels, has just been produced by the Coleman Motors Corporation, Washington, D.C., U.S.A. It has been designed for dealing with comparatively heavy loads off the main roads, and is equipped with 42 in. by 9 in. single pneumatic tyres all round, although twin pneumatics can be supplied for the rear wheels if required.
The wheelbase between the first and second axles is 12 ft. and between the second and third axles 4 ft. 5 ins. Behind the cab there is a loading space of 18 ft. The power Unit is a six-cylialered model G.L. Buda, with " coil and distributor ignition, electric starter and dynamo. Combined with the four-speed Fuller gearbox is a Coleman auxiliary gear with a low ratio of 548 to 1, the combination giving the. vehicleeight speeds in the forward direction and two in reverse. The highest gear is 8 to 1 and the lowest 176 to 1.
The two axles at the rear are of Wisconsin make with overhead worm drive. Each axle is carried by two semi-elliptic springs pivoted to brackets carried on the frame between the axles, the opposite ends of the springs being shackled to fur
ther brackets. There are no torque members or radius rods, the reactions being taken entirely through the springs. A short propeller shaft equipped with two universal joints connects the second axle to the third axle.
One of the most interesting points in the chassis is, of course, the driven front axle, which is a Wisconsin double-reduction type, to which the Coleman pattern frontwheel-driving mechanism is fitted. No differential is provided between the front and rear drives, whilst locking differentials are utilized in the two axles at the rear. It is
claimed that the combination gives
a positive drive at all times. . The gearbox is, of course, a separate unit, the 'drive being taken fore and aft by Spicer-jointed propeller shafts. Starting is effected by a gear of the ROES cam-and-lever type. Petrol is supplied from two cylindrical tanks mounted on the outsides of the frame side members. Each holds 22 gallons of fuel which is fed to the carburetter by a twogallon Stewart vacuum tank, which is an unusually large-capacity model for a vehicle of this load capacity.
A hand-brake takes action upon a drum carried on the auxiliary-gear shaft, whilst the service brake acts on all four rear wheels. This latter
brake is actuated through compressed air supplied from a Westinghouse pump driven from the timing gears.
It would appear that a chassis of this type affording such a great adhesion due to the distribution of the drive would be particularly suitable for military transport work.