"The Commercial Moto
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Tests British Vehicles—
Li
rdcilesell it QNE of the new models put at my disposal was a ‘-"Ford Pilot pick-up, and I collected it from the vehicle park, where it had been serviced after leaving the quayside, in preparation for delivery to the oilfields. There were fewer than 50 miles showing on the meter when I took charge, so in fairness to the operator, I spent half a day running-in the vehicle before starting its trials.
A development of the Ford Pilot car, the pick-up model has the eight-cylindered side-valve petrol engine, which develops g5 b.h.p. at 3,500 r.p.m., and a threespeed synchromesh gearbox. The gear lever is attached to the steering-column tube.
The commercial model retains the transverse semielliptic springs and double-acting hydraulic shock absorbers. Hydro-mechanical brakes take effect on all four wheels.
Equipment for measuring fuel consumption fitted at the Main garage in Abadan, and 10 1-cwt. bags of cement were added as payload. In the oilfields area the pick-up carries pipe-line valves, transport spares, boring equipment, stores and other loads which are either concentrated or bulky. It is a handy vehicle for such duties, having a loading height of 2 ft. 6 ins, and a body 4 ft. 10 ins. long, 3 ft. 10 ins, wide and 1 ft. 6 ins, high at the side boards.
In the course of operations in Iran, the Ford is driven more on the desert than on the road, so my test• combined desert and road work to simulate working conditions. I drove on the road during the running-in period and restricted the speed to 35 Comparative tests made on the smooth surface of the desert produced slightly better results, but the overall difference was too small to make any material difference. Sharp brake applications on the smooth surface caused extensive tyre slip, and similar treatment on the road caused the wheels to lock and bounce from rut to rut. The stopping distances were unsatisfactory in both cases, but there was evidence that, given a good road surface, the braking efficiency would be higher.
Fuel consumption was measured by driving 20 miles on a straight, level road, and returning the same distance on the desert. I saw fewer than a dozen vehicles during these trials, and an average speed of 40 m.p.h. was easily maintained.
There was a slight following wind in the northerly direction. It was blowing from the Persian Gulf, and the atmospheric temperature was in the region of 129 degrees. At the end of the road trial the radiator water was boiling violently, but a special tropical radiator would have been required to keep the water temperature within 100 degrees of ambient. At the end of this run 7.55 pints of petrol were needed to replenish the tank to the original level, which gives a consumption rate of 21.2 m.p.g.
The return journey on the desert was made at a similar speed. Its surface was smoother than the road, but a number of soft patches increased the tractive effort for short periods. Although chassis and body life might be lengthened by running on the desert, I think fuel consumption would be increased. Driving on the desert, my average speed was 2 m.p.h. slower than on the outward test, and the fuel return worked out at 18.7 m.p.g. That the heat of the day has an adverse effect on fuel consumption has been proved by tests made in summer and winter in Iran, and the results of my trials were later confirmed by the ojnrator's experience.
As I was driving into the wind on the return journey, there was a greater volume of air passing through the radiator, and the water temperature dropped to 2 degrees below boiling point. The engine-oil temperature was 204 degrees F. at the start and finish of the return journey.
There was no opportunity of testing the Ford's agility in a level southern area, so I made a short hill-climb with another vehicle at Masjid-i-Sulaiman, which is in the foothills of Iran. It romped up the inclines. The smoothness of the clutch was confirmed by a stop-start test on a gradient of I in 11. Although having an abundance of power on hard road surfaces, there are many occasions when extra pull is required to cross sand dunes when engaged in pipeline repairs. The Ford Pilot has always that additional power in reserve.
IT was only with difficulty that I obtained a Commer I underfloor-engined model for test. The oil compan:. has six of these vehicles under review in the whole of Iran, two being allocated to each of three areas. pursued the course of these Cornrners for several hundred miles, and finally ran one to earth at Masjid-iSulaiman.
The course selected for this model involved a climb over a mountain range, and provided scope for measuring the efficiency of the engine-cooling arrangements and assessing the advantages of an engine-free cab in a tropical area. Although five of the underfloor-engined chassis are fitted with drop-sided bodies, the vehicle tested had a refrigerator body, its daily round of deliveries in the foothills including scaling long gradients.
High-powered Engine It was a standard left-hand-control model, having a six-cylindered 109 b.h.p. overhead-valve petrol engine, which is carried in the frame in a semi-horizontal position beneath the seat of the cab. The cylinder block has a porous chromium deposit on the cylinder bores to improve engine life, and all components and accessories are arranged on the upper side of the power unit to increase accessibility. Cooling is by a centrifugal pump in conjunction with a I9-in. six-bladed cowled fan, and a radiator block located under the cab floor.
Transmission to the rear wheels is through a 12-in.diameter clutch and four-speed gearbox with constantmesh gearing for the third and fourth ratios. The braking system incorporates a vacuum servo operating through a hydraulic system to the two-leading-shoe units at all wheels.
The test chassis had only recently been put into service, having covered 6,000 miles, when 1 located it at the oilfields depot. During the short journey to the workshops to collect the load, the driver complained of heavy steering. This, I found, was caused by insufficient pressure in the tyres. To inflate them was a major task. The first pump failed at half-pressure, and the stand-by machine was a small model which worked only with careful coaxing. The rear-tyre pressures also required adjustment, and to add to the difficulties, the inner wheels had been fitted without positioning the valves opposite an aperture in the outer disc, so that both wheels had to be removed and turned. I look forward to the time when manufacturers will provide a foolproof arrangement to prevent occurrences of this kind.
It was well past midday when the Commer was ready for the road. The petrol tank was filled to overflowing, so that an average consumption could be ascertained over the complete journey. With the tyres inflated to correct pressure, I found the steering to be normal, and although driving at this time of the day was warm work, it was not because of heavy steering.
A Lively Performance Although the road surface was reasonable for the first 10 miles, there were numerous bends and hillocks, which prevented my giving the Commer its head. The addition of a 6-ton load did not greatly affect the liveliness of the high-powered engine, most of the minor gradients being climbed in top gear.
Large cavities in the road restricted speed on the approach to the top of the mountain range, and after a long stretch of driving over such surfaces I realized that the addition of shock absorbers would prevent a lot of driving discomfort and make the chassis more docile.
I took no risks on the 51-mile descent to the plains and engaged second gear for the entire run. The road, following the contour of the mountains, wound round innumerable hairpin bends with a sheer drop to the valley more than 100 ft. below. It was a tedious journey, and I was thankful that the oil-bound road surface was dry, otherwise the descent might have been hazardous in the extreme.
The long, flat roads across the plain invited an increase in pace, and the Commer was accelerated to the maximum. There were many occasions when the speed was over 50 m.p.h., and 45 m.p.h. proved to be a reasonable cruising speed. Having enjoyed a spell of fast driving without infringing the law, I slackened pace to check the chassis performance.
The running weight of the machine was near that of the underfloor-engined Commer that I tested in this country, so I found an interesting comparison in the results, With an atmospheric temperature of 128 degrees F., the van accelerated through the gears to 30 m.p.h. in 50 secs. This is 15 secs. slower than the time taken for the test made in this country.
Tests showed that the efficiency of the brakes, when cold, had not been impaired in the 6,000 miles of service, the stopping distance being 40 ft. from 30 m.p.h. This is within close limits of the figure yielded by my original test.
I drove the next few miles into Dar-i-Khazineh at a steady speed of 40 m.p.h., and stopped in the town with the intention of checking running tern peratures. Unfortunately, the radiator header tank was dry. I therefore abandoned the idea of taking temperatures and made for the nearest water point. As it was mid-afternoon the entire population had retired for its siesta, and to find water, plus a receptacle, was a problem. I could not risk the return journey without replenishing the radiator, because there is no camp or village between D.-i-K. and M.-i-S., a distance of nearly 40 miles.
Iron ingots were carried as a representative payload, and the Commer was driven on its return journey with the same load. I wasted no time in reaching the foot of the mountains, covering the first 12 miles at an average speed of 42 m.p.h. Temperatures taken at this point showed the engine oil at 198 degrees F. and the radiator header tank at 206 degrees F.
A 5+-mile Climb
Third gear was employed for the initial stages of the 5i-mile climb, and gradients of 1 in 11 were scaled with a reserve of power. There was a slight fall in power as the climb continued, and second gear had to be engaged on a section of 1 in 12 near the top of the mountain. It took 18i minutes to climb 9 kiloms., which gives an average speed of 18.3 m.p.h., a remarkable result, considering the gradients and the bends.
There was a stiff breeze blowing at the top of the mountain, where a short bait was made for final temperature readings. I found that the radiator header tank had again boiled dry, but water could be heard bubbling in the cylinder head and pipes. The engine-oil temperature had risen by 20 degrees during the climb and the ambient had fallen to 114 degrees F.
After permitting the engine to idle for a period while it cooled to a normal temperature, the Persian driver took over for the return run to our starting point. Unfortunately, the engine stalled and the starter dog refused to engage on the ring. I was forced to remove the starter motor and make a hurried inspection. The cause of the trouble could not be traced, so I replaced the motor, and the engine started without further loss of time.
The outstanding conclusion reached during this test was that the temperature in the cab was appreciably lower than that of the outside atmosphere. The heat from she engine is conducted away behind the cab, and the driver does not suffer discomfort from over-heated floorboards or bonnet covers. Apart from the suspension and the position of the hand-brake lever, I found the Commer a reasonable vehicle to drive in the tropical areas.
The average fuel consumption taken over the 80-mile run worked out at the rate of 9.8 m.p.g., which is extremely satisfactory having regard to the long climb up the mountain, the high average speed on the plains, and the numerous stops and starts for performance trials.
BORROWING vehicles from an operator for test was
an advantage, because it provided an opportunity of assessing the performance of used machines. The Bedford 5-tonner I selected for trial had covered 24,700 miles, and the vehicle's history card showed that, apart from minor adjustments, the chassis was "as received," no unit changes having been made.
This chassis was a standard left-hand-drive semiforward-control long-wheelbase model equipped with a stake-sided body. It had a six-cylindered overheadvalve engine, which develops 72 b.h.p. at 3,000 r.p.m., and a four-speed gearbox with dog engagement for the direct-drive ratio. Transmission is through two propeller shafts to a spiral-bevel final-drive assembly in the fully floating rear axle. The hydraulic braking system has a vacuum servo. The two brake shoes in each drum are linked to give a marked servo action.
In Good Condition Although approaching the second quarter of its life, according to Anglo-Iranian standards, the Bedford was showing few visible signs of its age. The bonnet sides had been removed, which is customary during summer in hot areas, and the wings had a few bruises. Because of the body overhang there were no wings to the rear wheels. Both doors to the cab could be opened or closed without undue effort, although rough work had caused movement and wear on the hinges and locks. The side lamps had been removed as a precaution against theft, but the head lamps were left in position in case of an emergency.
When I collected the Bedford it was part-loaded with 3 tons of cement in bags, which were to be delivered to Sarri Ghatch, a tank-farm site at the top of the mountain range 10 miles away from Masjid-i-Salaiman. There is no test course in the British Isles comparable in the combination of length and severity of gradient and tortuosity of route.
The petrol tank was filled before leaving the town, and a note made of the mileometer reading. I was accompanied on the trials by, the oilfields transport
officer, Mr. I. Parry, who drove the Bedford to the foot of the mountain. At this point I took the running temperatures, finding the radiator water to be 184 degrees F., engine oil 204 degrees F. and ambient 118 degrees F.
Then began the long, winding climb over the mountain range. There were many points where the Tapley gradient meter registered an incline of 1 in 91, and the average gradient for the first five miles was 1 in 25. This called for extensive employment of second and third gears, and wherever there was a level stretch it was accompanied by a sharp bend which prevented the use of direct drive. Compared with many parts of Iran, the mountain road was in fair condition. It had a rolled oil-bound surface which, although being reasonable to drive on in summer, would be difficult to negotiate in had weather.
Cab Temperature Rise
The Redford climbed gallantly, but the temperature of the cab, floor plates and bonnet increased rapidly with the distance travelled. The floor plates became so warm that the heat penetrated through my shoes, and the bonnet was given as wide a berth as possible. At one point the cab temperature registered 138 degrees F., which was somewhat warmer than the surrounding temperature.
It took 22 minutes to reach the top of the range, the long climb being sufficient to raise the water temperature to boiling point and increase the engine-oil temperature to 232 degrees F.; ambient remained unchanged. The road to Sarri Ghatch ended abruptly at the summit of the mountain range, where a cable railway is employed to lower material down the mountain side. With the trolley detached, vehicles can be hooked on the rope for assistance up or down the gradient of 1 in I. Luckily, 1 was spared this experience, and after taking on the load
for the return trip the Bedford was driven back over its original route.
I drove with care when descending the mountain, selecting third gear and using the brakes only for slowing down at the bends. On many of the curves there was only a shallow crumbling wall between the road and a 103-ft. drop to the valley below. Although the brakes were used more extensively towards the foot of the mountain, they withstood the test without giving me cause for apprehension.
Testing Under Difficulties
Instead of returning direct to the depot, I made a detour towards Bibian, where a short level stretch of road was available for measuring braking distances and checking acceleration rates. These trials were made under difficulties, because there was a humpback bridge at one end of the course and the road surface was badly holed. In addition numerous tests were foiled by pedestrians and mules straying across the road. The acceleration results, when finally taken, showed that the Bedford engine had not deteriorated in power during its 24,000mile life, 30 m.p.h. from rest being reached in 30.2 secs. This must have been an exceptional vehicle, because most engines in tropical areas are ready for rebore at this mileage.
It was difficult to assess braking efficiency because of poor adhesion between the tyres and the rough road surface. As a guide to their effect, the vehicle was brought to rest in 20 ft. from 20 m.p.h. when the pedal was applied in an emergency. The wheels locked, and bumped across the holes for nearly 15 ft. The fuel tank was refilled at the petrol station, 21i litres having been used. This equals a fuel consumption of 0.295 litres per kilom., or 9.6 m.p.g. Considering the long climb and number of stops made in the performance trials, the economy of the Bedford appears to be almost unaffected by tropical operation.