Performance Lives Up to Appearance
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Perkins R6 Oil Engine and 10 Forward Speeds Give Abundant Power in Rutland Troubadour
8-tonner By Laurence J. Cotton
M.I.R.T.E.
THE appearance and performance of the Rutland Troubadour normal control 8 tanner are impressive. An imposing bonnet, over 5 ft. long, covering the Perkins R6 108 b.h.p. oil engine and radiator, creates an atmosphere of abundant power, which indeed exists with the torque of the R6 unit and 10 forward gear ratios.
The Troubadour has been designed for tough work in difficult areas and has such features as a 10-in.-deep frame of A-in. section, which is fully capable of carrying loads in excess of 8 tons under continuously adverse conditions. The steering gear, axles and braking equipment are of equally robust proportions. This model forms the basis of the Rutland six-wheeled tractor with a double-drive bogie and Gardner sixor eight-cylindered oil engine; the vehicle in this case has conventional forward control. When built as a six-wheeler the clutch, braking equipment, transmission, tyre size and frame thickness, are stepped up accordingly.
With the R6 oil engine installed there is space round the unit for adequate ventilation, and with both sides of the bonnet made to open the components are easily reached. A cast light-alloy tread plate is fitted adjacent to the bonnet so that normal servicing or repair is done with ease, the fitter sitting on the wing and using the tread plate as a bench. The steering is set back from the normal forward attachment and mounted at an angle to provide a comfortable driving position.
B14 The David Brown 45 five-speed direct-drive-top gearbox and Borg and Beck 14-in-diameter clutch are mounted with the engine, a rear extension being provided to the selector turret to provide for the gear lever being positioned for easy manipulation. Because of the 17-ft. 6-in, wheelbase, a three-piece propeller shaft is required, this having two support bearings, insulated from the frame, and Layrub Type 100 couplings, An Eaton Type 16,500 two-speed axle is used and the Kirkstall front axle is a heavy-duty unit. The braking system incorporates a Clayton Dewandre 8-in.diameter vacuum servo which operates through a Girling hydraulic system to two-leading-shoe Units at all wheels.
The Troubadour is intended for fast long-distance work and is well equipped against brake fade by having 15-in.diameter drums to promote cooling and to prevent heat transfer to the tyres. What is lost in drum diameter is more than counterbalanced by using wide shoes, those at the front axle being 4+ in. Wide, and providing a total facing frictional area of 544 sq. in.
The long frame was loaded with concrete blocks, 5 tons being accommodated amidships, and 3 tons behind the axle. This would provide a reasonable distribution for normal loading with a body fitted and of the total weight, 44 tons was imposed on the front axle and 8 tons at the rear.
Starting from Croydon the chassis was headed towards the hills, with Mr. Frank Manton, A.M.I.Mech.E., the managing director and designer of the Rutland range, at the wheel. The engine and transmission had not reached normal working temperatures in the short run to Spout Hill and on the first trial it just failed to make the 1 in 64 gradient in second gear. A stopstart test, with high-first gear engaged, was accomplished at this point. After turning at the top of this gradient the Troubadour was driven to Succombs Hill, and approaching from the top the brakes were used freely for the 700-yd. descent. I had previously set the Tapley brake meter, and an emergency stop just before the roundabout produced a reading of 65 per cent with all wheels locking evenly. This brake-fade test was repeated after a second descent, without loss of efficiency.
Succombs Hill is a freak climb which would not be encountered in normal service either in this country or overseas, and the chassis tested was essentially an " open-road " type for fast Continental trunk operation. Low gear. was initially required on the 1 in 5 section, and the engine pulled well. The 1 in 41 section near the brow caused a drop in engine speed and this gradient is about the maximum that could be climbed with the nominal load, After the hill trials an attempt was made to run a high-speed consumption test between Godstone and East Grinstead but because of traffic conditions this met with little success. Ultimately, this test was made on the LondonHastings road between Farnborough and Poll Hill, where although less traffic was encountered there was a steady rise for over three miles on the outward part of the journey.
There were two roundabouts to be negotiated, and here I found the steer
ing to be positive and reasonably light. The roundabouts and the long incline were obviously responsible for a reduction in the average speed for the journey, so whereas the nominal pace was kept to about 45 m.p.h. the mean speed worked out to 34.3 m.p.h. for the first trial.
Although full throttle was required when accelerating and on the long gradient where the low-fifth gear was used, the remainder of the journey was covered on part throttle, and the fuel return was accordingly good for the R6 unit, working out as it did to 14.5 m.p.g.
15.8 m.p.g. at 29.7 m.p.h.
A second trial was made restricting the speed to 35 m.p.h. from which was derived an average of 29.7 m.p.h. for the run, with a fuel-consumption rate of 15.8 m.p.g. The Rutland Troubadour is made to operate fast schedules, and 45 m.p.h. is a comfortable gait which can be maintained without taxing the engine, but if economy in fuel is required it will pay to reduce the speed to nearer 35 m.p.h.
The engine-oil and water temperatures, at 110° F. and 118° F. respectively were far below the optimum for high thermal efficiency, and partial blanking of the radiator would improve fuel consumption figures. These temperatures, representing 50° F. above ambient, indicate that the vehicle is adequately equipped for operation in warmer territories.
In 80 miles driving I found the braking system to be progressive and effective, and when it came to testing the retardation, 150 lb. pressure on the pedal was sufficient to lock the wheels. The results of 12 successive trials at 20 m.p.h. and 30 m.p.h. were remark
ably consistent. The spread at the higher speed was 62-65 ft., the tyre skid marks being of about equal length.
There was less wheel locking at 20 rn,p.h., at which an average retardation of 0.59 g. was obtained. It was apparent that a better road surface would be required to assess the true efficiency of the braking system.
The acceleration trials were made first with the lower ratio of the axle and second, third and fourth gears engaged, with a swift change in axle ratio at 27 m.p.h. to reach 30 m.p,h. in 38.6 sec. With 10 forward gears, aligning well in their steps with the range of engine speed, the Troubadour is not lacking in a ratio for any type of gradient, and can be relied upon to climb hills faster than contemporary models having a fixed ratio axle.
In appearance and performance the Rutland can compete with any of its foreign rivals, and built with traditional British thoroughness, it should have a long life. The bluff styling of the front fairing .is unusual and unlikely to be outdated for many years ahead.