The Galloping Major
Page 44
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By A. J. P. Wilding
The Nubian Major was introduced at the Commercial Motor Show and the design was fully described in The Commercial Motor of September 4, 1964. Brief details of the mechanical specification are included in the accompanying table. This model is essentially a more powerful version of the earlier Nubian and was introduced to-meet the need for an airfield crash and water/foam tender with a capacity and performance to meet the needs of larger airfields and runways. When used by the Services, this type of machine is also called upon to traverse rough ground, and the demonstrations were arranged to show that the model was suitable for this type of use also.
The circuits -used at Bagshot Heath included gradients of up to 1 in 3 severity, Jong slopes of less gradient, stretches of deeply pot-holed tracks and a generally rough gravel road. The test chassis went round the 5-mile circuit selected more or less continuously for about 2-5 hours in the morning and a further hour in the afternoon, making about 10 or so trips in all. Speeds on the runs were up to 35 m.p.h., which was high considering the surface conditions, and at no time did the Nubian Major get into difficulties.
The ride given was very good, the suspension being well up to the demands made of it. No shocks were transmitted through the seats erected for passengers except when the rear axles came against their restricting slings. This was in spite c24
of the fact that the front wheels were clear of the ground on many occasions. I drove the test vehicle on one of the afternoon runs and found that only a short time was required to get used to the feel of it and to make the best use of the high-revving Cummins V8 engine. During my turn at the wheel the surface of the tracks had become slippery in places because of rain, but the Nubian Major hung on to the ground extremely well and surmounted all the inclines with ease.
For the type of ground covered, the high power of the engine 300 b.h.p.—was a great advantage and also a considerable help in manceuvring the chassis around the site. Also a great help on steep bends on the circuit was the direct-air ratio-change system for the semi-automatic, fivespeed, epicyclic gearbox. It was noticeable that to maintain the perforrnance it was necessary to keep the engine speed at around 2,000 to 2,500 r.p.m. at least; below this speed, power soon fell away and running at less than 1,500 r.p.m. was not satisfactory as the fluid clutch did not lock up until that speed was reached. All the running was done with the auxiliary gearbox in low ratio—it is not possible to change ratios in this box except when stationary. This gives the effect of providing an extra-low bottom gear and makes top gear 1-64 to 1, which is thus virtually the same as the 1-59 to 1 fourth gear when the high auxiliary ratio is used. As it turned out, the test would have been