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17th December 1948
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Page 36, 17th December 1948 — stanv with !
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By-----L. J. COTTON, M.I.R.T.E. ADICTIONARY describes a mustang as a fast American horse and the characteristic of fleetness is certainly to be found -in the Maudslay model bearing that name In its pulling power and stamina, however, it more closely resembles the fine old British Suffolk Punch. On test the Mustang showed exceptional top gear acceleration and generally proved to be fully capable of drawing a heavily laden trailer

The model tested—at present offered only for export—was equipped with the A.E.C. 9.6-litre oil engin and, compared with the smaller-engined home model, the high performance of the export chassis fully justifies the fitting of the more powerful unit Chassis Frame Strengthened In addition to the larger engine, the 9.6-litre chassis has been .modified to afford greater rigidity. The frame side and cross-members are deeper and the frame width has been decreased to permit larger-sectioned tyres to be fitted. To improve suspension and afford better weight distribution, the wheelbase has been lengthened from 16 It. to 18 ft. by altering the position of the rear axle.

The 8-ft. wide model supplied•for my Lest had left-hand steering, and the fuel-injection pump, exhauster and other auxiliaries were arranged on the right-hand side for greater accessibility.

Engine, clutch and gearbox, bolted together to form a unit, are retained in the chassis on a flexible threepoint-controlled rubber mounting. Of unit construction, the David Brown five-speed gearbox has a top ratio of 1 to 1, which, with a finaldrive ratio of 6.5 to 1, affords a maximum road speed of 37-38 m.p.h.

Open tubular propeller shafts, carrying the drive to the rear axle, are retained by a self-aligning bearing housed on the centre cross-member The single rear axle is of fully floating pattern with an overhead-worm drive.

Girling two-leading-shoe wheel units, incorporated in the braking system, arc operated through a Clayton Dewandre servo and Lockheed hydraulic cylinder. A tandem master cylinder is employed as a safeguard against complete loss of braking effort should a pipeline frac ture on the hydraulic system The hand brake, operating on the centre and rear axles, is interconnected and fully compensated between the two axles A number of refinements has been made to the frame, the side and cross-members being increased in depth by 1 in.. and the flange width

is now 2-4 ins. The 8-ft.-wide model has a frame wiath of 2 ft. Ili ins., which is 1 ins, less than in the home chassis of 7-ft. 6-in, overall width. This follows the trend of Continental design and permits 11-in by 20-in tyres to be fitted.

In extending the wheelbase to 18 ft. the rear overhang has been decreased to 4 ft. 6 ins. Formerly carried at the rear of the chassis, the spare. wheel is now located amid

ships. With the larger tyre ecluipment and deeper frame, the loading height has been raised by 21 ins.

The 80-mile route planned for the day's trials included a fair measure

of town operation and sharp, narrow turns in the smaller villages. This, considered, would provide opportunity of assessing manceuvrability, and lightness of control. Collecting the Mustang from the Coventry works, I drove on the outward journey through Kenilworth, Warwick and Stratford, to the old-world village of Broadway.

Because of its width and weight, 1 at first treated the vehicle with caution, but soon gained confidence with the ease of control and the livelines of the power unit. A rapid mental calculation showed that when travelling at 20 m.p.k with top gear engaged, the engine speed was less than 1,000 r.p.m. This provided ample reason to increase speed to 30-35 m.p.h. on major roads.

A right-angle turn in the narrow thoroughfares of Kenilworth demonstrated that the Mustang could he

piloted through restricted areas without causing inconvenience to other drivers. The narrow corner pillars of the cab and the deep windscreen afforded excellent visibility, and the controls were positioned to require the minimum of movement.

A level stretch of road between Stratford and Mickleton was found suitable for the first part of the tests. The acceleration trials showed that the Maudslay did not lack liveliness, 20 m.p.h. being reached from rest in 15 secs. and 30 m.p.h. in 33.1 secs.

Considering the gross weight of the vehicle (over 161 tons) and the comparatively high ratio in the combination of the final drive and tyre size, the top-gear performance reflects credit on the flexibility and torque of the engine at low speeds. There was a slight propeller-shaft rattle between 12 and 16 m.p.h., but apart from this speed was increased smoothly and steadily An average of times recorded shows that from 10 M.p.h., 20 m.p.h. could be reached in 12.8 secs., and 30 m.p.h. in 25.7 secs.

Braking tests were made over the same course, and with emergency applications, the Mustang was brought to rest in 58 ft. from 30 m.p.h. and 31 ft. from 20 m.p.h. In general terms, these results equal efficiencies of 52 and 43 per cent. respectively.

After these trials, I continued to Broadway in preparation for climbing Fish Hill, which presented a 1.8mile gradient equal to about 1 in 8.5. A thermometer was left in the top tank of the radiator to check the rise in temperature, and it registered 121 degrees F. at the foot of the hill. Starting the test in second gear, third and fourth gears were quickly engaged, and held for the first 300 yds., where the steep incline enforced engagement of lower ratios.

Second gear was used for nearly miles, and although the climb was tough, the engine was turning at governed speed for most of the period. The radiator temperature rose steadily to 144 degrees F. for the first four minutes of the climb, and then the cooling-water temperature settled down and remained constant at 145 degrees F. This shows that the cooling system is adequate, even for hot summer conditions, because although the atmospheric temperature at the time was 38 degrees F., the cooling water would still have been below boiling point had the ambient temperature been 100 degrees F.

Ample Power A halt was made on the hill to check ability to start on a gradient. When stationary, the Tapley meter registered a gradient of I in 7i. This provided no problem to the Maudslay, with its high power-toweight ratio, and the start was accomplished in second gear without the slightest difficulty.

Lubricating-oil temperatures were taken at the top of the hill. After the long climb, I expected to find overheating, but the engine oil registered a mere 170 degrees F. When removing the dip-stick to take this reading I found a point to criticize in the shortness of the dipstick handle, and would prefer to see it lengthened for convenience.

A temperature of 252 degrees F. 133 was recorded for the lubricant in the rear axle. Although higher than normal axle temperatures, it is reasonable for a heavily loaded. single-axle-drive six-wheeler.

In descending Fish Hill the brakes were used to check the speed to 25 m.p.h., and by the time Broadway was .reachedthey -were showing obvious signs of overheating. A spot check on the stopping distance from 20 m.p.h. revealed that their efficiency had actually increased, probably because the chassis had covered only a few miles and the continued use of the brakes had rubbed the high spots off the facings, thus increasing the friction area.

Fuel consumption tests were made between Stratford and Kenilworth on the return journey. Starting from the foot of Blackdown Hill, on the outskirts of Stratford, fourth gear was employed until the summit was reached.

Upon driving into Warwick, some slow traffic hindered progress for nearly a mile and intermediate gears had to be used for most of that B4 distance. After a short delay at the traffic lights, the steep climb out of the town again enforced considerable use of indirect gears, and, calculated on a time basis, 22 per cent, of the trial was made in the intermediate ratios.

Conditions were hardly conducive to inflated results, and it speaks well for the Mustang that an average consumption equivalent to 7.73 m.p.g. was maintained. By a direct calculation from the time spent in indirect gears, I concluded that, given a test of average town and country operation, the rate of consumption would be 9-9.5 m.p.g.

It must be appreciated that the machine was carrying over •a ton more than the normal load, and that a vehicle of this capacity is usually engaged on long-distance haulage. An operator using this machine to carry a 10-ton payload on trunk haulage 'should get a fuel return of 10-11 m.p.g.

Acceleration, braking and general handling of the Mustang provide a convincing case of raising to 30 m.p.h. the legal speed of heavy vehicles. Although the vehicle was 8 ft. wide, had left-hand drive and was tested at a high speed over a difficult course, there was no occasion in the 80-mile run when it could be considered unsafe or be said to have caused any impediment to traffic.

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Locations: Coventry, Broadway

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