T 13 convince a representative of the newly forr Bombay State
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transport organization that the engined light passenger chassis could give a gi performance under the most adverse conditions 345-mile trial was planned, to include scaling the Wesi Ghats from sea level, fording a river and running long distances over roads normally considered unfit this class of vehicle.
The subject of this test was a Commer Comma, chassis fitted with a Perkins P6 oil engine. It was first of a batch of 66 of the same make and type wl were to be added to the Bombay transport fleet at rate of 12 every fortnight, and was the organizati, first oiler. The 30-seater body, which survived the tr without undue wear and tear, was built by McKern Ltd., Bombay.
Major H. Walmsley, the deputy general manager the Bombay State transport authority, together with representatives of the bodybuilder and chassis distributor, were present on the trials as observers. Sandbag ballast weights were carried to give a total running weight of 14,448 lb. (6 tons 9 cwt.).
Starting the tests from Bombay, at sea level, the first 63 miles of the reasonably level and good road Was covered at an average speed of 31 m.p.h. Considering that the maximum governed speed was 36 m.p.h., the
:nt Commer maintained a remarkably fast schedule. The Bhor Ghat, a climb of 1,604 ft. in 6 miles, with an average gradient of 1 in 20, required full use of the intermediate gears, and 1-in-6 gradients were sealed in second gear.
Although the day temperature was 87 degrees F., arid the engine was pulling at maximum revolutions for 33 minutes, the highest temperatures recorded for the engine oil and radiator top tank were 167 degrees F. and 147 degrees F., respectively. Because of the good steering lock, numerous hairpin bends encountered during this climb were negotiated without the necessity of reversing on any occasion.
Katraj Ghat presented an 11-mile
itted With Perkins acclivity from Poona, rising from
1,887 ft to 3,034 ft. above sea level.
:r Most Exacting This required comparatively little tern Ghats. No effort from the Commando, the at Altitudes as climb being made using the third
and direct-drive ratios. There was
ye Sea Level a slight increase in operating temperatures, but the highest readings were recorded on the Khambatgi Ghat, where the water temperature reached 190 degrees F., and the sump oil 194 degrees F. Atmospheric temperature at the peak was 83 degrees F.
The most difficult climb of the course was from Wai to Parsini Ghat, where the road rose from 2,467 ft. to 4,133 ft. in 8 miles, an average gradient of I in 25. -1-his was a test for the engine, because it was expected that there would be a definite power loss at high altitude. Although on full throttle, there was no trace of smoke from the exhaust, and the engine continued to pull steadily without apparent deterioration in power. Atmospheric and running temperatures, at the peak of the Parsini Ghat, were a few degrees lower than on the previous climb.
The gradient continued, to a lesser degree, for a further 15 miles, by which time we had reached Mahableshwar, 4,626 ft. above sea level. This was the highest point of the route, and the start of a 23-mile descent of an average gradient of I in 20.
Testing for Brake Fade To test the efficiency and possible fading of the brakes, top gear was engaged for the descent, and speed held in check by applying the brakes. Hairpin bends were negotiated at the rate of two to every mile, and although on a bad road surface, there was no occasion for apprehension for the lack of stopping power. This serious misuse of the brakes was all part of the test, but for the safety of passengers service drivers should be instructed to use an intermediate gear for a similar descent.
For the next 80 miles, we travelled over deep potholed earthen road surfaces, which are normally thought unfit for this class of traffic, providing an excellent test for the suspension. The bus swayed and bounced, even at the comparatively low speed of 18-20 m.p.h. The Commando suspension and bodywork survived this trial without fracture or weakening. A further obstacle was provided at the river crossing at Pen, where the Irish Bridge, constructed in 1850, would not take the weight of the fully laden Commer Fortunately it was not the monsoon season, and the water lesel was fairly low The driver decided to risk fording the river, and the water rose above axle level. No apparent harm was done to the chassis, although the brakes lost some of their efficiency for a short period Once on dry soil, a few sharp applications of the brakes were made to help to dry the facings, .ind their efficiency was rapidly restored.
A close check was made on the fuel consumed, and at the end of the course a total of 22 gallons 3i pints had been used. This corresponds to 15.3 m.p.g., which
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might be considered a creditable result for such a hazardous course requiring constant use of intermediate gears and with a fully laden vehicle. The oil consumption was practicallY. negligible, requiring only 1} pitits to restore it to the original level. This isequivalent to 2,070 m.p.g.
After these trials, the Commando was taken, without preliminary adjustments, to a level stretch of road in the Bombay area, where acceleration. braking, consumption and other tests were made.
It was established that from 20 m.p.h. the vehicle could be brought to rest in 20.5 ft. and from 30 m.p.h. in 35.8 ft.—exceptional braking, considering that both axles had been immersed in water when fording the river, and that the brakes had been used continuously for the descent from Mahableshwar.
Acceleration was well within standard performance, 30 m.p.h being reached from rest in 25 secs. Most outstanding in the performance results was. the fuelconsumption test, which was conducted over a flat road at an average speed of 20 m.p.h. The results showed a fuel-consumption rate of 22.5 m.p.g.
Good Average L'needs The 187 miles from Bombay to Mahableshwar were covered in an actual running time of 7 hrs. 19 nuns. Considering that the steep ascent of the Ghats had been made and 10 per cent. of the distance covered at a height of over 4,000 ft. above sea level, the average speed of 25.7 m.p.h. is an excellent recommendation for the flexibility of the power unit.
During the return circuit, the 80 miles of bad road surface between Poladpur and Chowk severely restricted the speed, which reduced the overall average for the complete trial. The average speed for the 158 miles required to complete the return journey was 20 m.p.h. Only 18 miles of this part of the journey was over road surfaces which could compare with the Class I roads in this country.
In his comments on the trials, Major Walmsley attached great importance to the fuel economy, especially to the test with a measured half-gallon, which he termed "the final highlight of the tests." He considered the course to be most severe, and said that the Commer Commando had proved its ability to operate, with full satisfaction, in any part of the Bombay area.
Mr. Hootihan added that the machine used had been chosen at random from the first batch of vehicles received, and that the tests had revealed a better performance than that claimed by the manufacturer.