MOVING 12-TON LOADS AT 12 M.P.H.
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A New Powerful Lorry Chassis Capable of Hauling the Modern Full Load at Maximum Legal Speed on a Low Petrol Consumption.
WEREFERRED last week to the deraonstration carried out a. few days earlier by Dennis Bros., Ltd., of their new high-powered six-ton chassis, but au error in tranemission of our.message reduced the load on the trailer, which was actually six tons, in addition to the six tons conveyed by the lorry. .
The task of evolving a vehicle capable of handling a 12-ton load on a tire weight for lorry and trailer of 5 tons 18 cwt. 3 qrs. has been none too easy, for, with a powerful engine and a total load of nearly 18 tons, the,cluteh gear had to be particularly well deeignadr-ands.mede amply substantial. The designers had, as a basis for their work, the success of the 5•6-ton Dennis chassis with a40 h.p.' engine. Equipped with a four-cylinder engine, with a cylinder bore of IZI mm. and a.piston stroke a 180 mm., savable of developing 60 hp., Ferodo-lined clutch, a. four-speed. gearbox' and a worm-driven rear axle, the 6-ton Dennii is a robust construction, at once credit able to its makers and to British engineering.
Dennis's are fortunate in having almost at their door a wonderful teat ground in the Hog's Back, which 'carries the old Roman road running east to • west through Surrey, and in the gradients that give access to the road at the summit of the ridge. Leaving Guildford High Street, a sharp turn over the railway bridge is immediately followed by the steep ascent to the Hog's Back, the steepest portion of the gradient being 1 in 9. In the course of the demonstration the lorry, with a 6-ton Dyson trailer, each vehicle fully laden with concrete blocks, climbed steadily and apparently With ease. On the steepest grade the lorry came to a standstill and restarted without so much as a jerk. Proceeding -a few miles along the Hog's Back, the turning to Puttenham Was taken, Puttenhara Hill, as it is called, being a steep drop into the valley to the south of the ridge. The brakes were here given an opportunity to display their effectiveness, and at the foot of the hill the vehicle and its trailer were turned and
manoeuvred actually with less difficulty than was experienced by the private car which carried the observers of the test. ' The climb up Puttenham Hill, with a steep portion of 1 in 7.2, was performed no candy and at such a satisfactory speed that one could hardly have expected better with an unladen vehicle. Much of the hill was traversed on second gear. On the steepest portion the vehicle was twice stopped and restarted, and it easily ran away from the party of spectators which had 'proceeded. pp the hill on foot in order to watch the demonstration, and it turned on to the 'main road at a. junction which is a fierce little test in itself, making no more fuss about the job than if it were being essayed by an efficient private car. The standard 5-6-ton chassis has a.final •reduction in the back axle of 8.75 to 1; on the 6 tanner the final reduction is 9.66 to I, giving a reduction on lowest gear of 45 to 1. The controls seemed to us to impose the minimum of driving strain, and. one could only say of the demonstration that it was eminently satisfactory and
that the Dennis 6-tonner is a vehicle with an ample reserve of power with efficiency and thoroughness stamped throughout and With -every evidence of the Perfection of design and workmanship which one would expect from a concern with such a lengthy experience of oommercial-vehicle construction as Dennis Bros., Ltd. The fuel con:lump., tion claimed for the vehicle handling 12 tons is a gallon per five miles, which gives 60 ton-miles of pay load per gallon. This figure, arrived at over give-and-take roads, must be regarded as being -quite satisfactory.