ILITARY transport is rather a
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different proposition from or dinary haulage work, where practically all the\ running takes place over good " made " roads. For one thing, vehicles may be required in an emergency to cross open country and climb hills in hot climates. In order to assess the value of vehicles such as are now being sold to hauliers and traders by prominent manufacturers, a series of trials is necessary, and it was for this purpose that the War Department planned a course in North Wales which embraced conditions of service likely to be encountered by machines operat,ing in war time.
For military reasons, notably for that of bridging, the heaviest useful load carried by any vehicle in the geld is 3 tons, but the type of vehicle at present marketed with a capacity for a 3-ton pay-load would be useless for a similar load under service conditions. On the other hand, a four-wheeled 4-6ton lorry is much more likely to suit the requirements of the War Department when carrying the standard military load of 3 tons, and coupled, with a low gear ratio (usually provided to enable the lorry to haul a trailer) should give a high tractive effort and
B36 a performance sufficient to meet military needs.
Problems of engine cooling and tyre adhesion, braking capacities, etc., also arise. Certain manufacturers, therefore, were invited to submit vehicles to undergo tests covering the points outlined above. Six, vehicles were put through their paces. They were Max;
Maximum Torque
Vehicle. b.h.p. (lb.-ins.) Albion (model 54) ... as 12,300 r.p.m.) 3,100 Le),land Badger TA6 72 12,000 r.p.m.) 3,060
Matidslay 6-4 70 11,800 r.p.m.) 2,880 Morris-Commercial 0.8.0/60 70 {3,200 r.p.m.) 1,800 Thoingeroft E.E./S.C.6 72 (2,500 r.p.m.) 2,160 A.E.C. Matador ... 80 (2,400 r.p.m.) 2,700
Each vehicle had twin tyres at tho rear and a four-speed gearbox.
A report of the proceedings up to the afternoon of May 9 appeared in last week's issue.
The vehicles were all set to climb the new Horseshoe Pass, near Llangollen, a Fill with an average gradient of 1 in 19.6 throughout its length of 3.6 miles, the maximum incline being 1 in 6.69. All the machines made perfectly clean climbs, a point of interest being the comparative uniformity in the maximum cooling-water temperatures. They were all between 171 and 178 degrees F.
The times taken • to climb the. hill were also fairly close, varying fripm 1.2 mins. 5 secs. to 15 ruins, 30 sec3 The variation was due, no doubt, to "the exact suitability of the gear ratios oi the various vehicles for the particular hill.
Next came a rather more severe hillclimbing test, the Old Horseshoe Pass, which adioina the new road, being tackled. The length of this acclivity is 1.05 mile, the average gradient 1 in 8.15, with a maximum rise of 1 in 4.4. Again all vehicles made perfectly clean climbs with slightly higher cooling-water temperatures, although without indication of boiling. The times for the climb were again fairly closo, varying from 7 mins. 58 secs. to 10 mns. 4 secs.
To assess the performances of the vehicles under conditions of easy crosscountry running, two special tests were instituted. The first one involved the negotiation of a slope 227 ft. long, with an average gradient of 1 in 10 and a maximum rise of 1 in 8. The Albion, Mandalay and the A.E.C; all suffered slightly from wheel-spin, but otherwise made good climbs, the other machines taking the course easily.
The second cross-country lest was much more severe, for the maximum gradient was 1 in 417, whilst the average rise throughout the 421-ft. trial slope amounted to 1 in 6.9 on a grassy patch of land. The Albion made the best showing on this particular stretch, although it had little power in hand at the top. Lack of torque at the top of the slope stalled the Leyland, the remaining vehicles in the trial failing, although they reached within a few yards of the summit— one would suppose that lower gear ratios would make all the difference.
To climb Bwlch-y-groes from the south side is a really severe test for freight vehicles, for the hill is 1.62 mile long, with a maximum gradient of 1 in 3.5, the rise being 743 ft. per mile. A tribute must be paid to the manufacturers concerned, for no water had to he added to the cooling system and in only one instance did the temperature use momentarily to boiling point.
Conditions were made as severe as possible by the institution of stopping and restarting tests at two points in the climb, the first at a place where the gradient is 1 in 5 and the second where the rise is as steep as 1 in 4, Naturally, these tests involved a test of the brakes as well ; according to the observers' remarks, all vehicles left the mark smoothly, and the hand brakes held the machines from running backwards, except in one instance, where there was a little creeping.
The gear ratio of the Maudslay and the Thornycroft was a little too high to make a restart on the 1-in-4 section when fully loaded, so 15 cwt. was removed from the former machine and 10 cwt. from the latter, in order to allow them to get away. To start a gross load of approximately 8 tons on such a gradient is an extremely heavy test of the clutch, especially considering the' fact that in no case was the bottom gear of any vehicle lower than 40.9 to 1. The mere" fact that only 15 cwt. on one vehicle and 10 cwt. on another had to be removed in order to allow two out of six machines to get under way 'speaks volumes to anyone who understands the operating conditions.
A subsequent brake test at a point with a decline of 1 in 4 showed that all brakes, both hand and foot systems, were holding satisfactorily.
The performance of these vehicles must surely be regarded by the authorities with eminent satisfaction. They were operating under conditions for which they were not designed, and everything, including electrical equipment, tyres, gear ratios, steering gear, etc., was exactly as produced and sold by the manufacturers.. Thus the versatility of the modern goods vehicle has once again been clearly demonstrated, and the all-round good showing made by the machines should prove to be excellent propaganda for overseas sales.