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Happy 0 or Off the Road

7th March 1952, Page 42
7th March 1952
Page 42
Page 43
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Page 42, 7th March 1952 — Happy 0 or Off the Road
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Which of the following most accurately describes the problem?

By L. J. COTTON M.I.R.T.E.

A. GRUELLING 30-mile endurance test across fields and unmade roads, in quarries and in a sand OA, found only minor failings in the Austin A70 pick-up, and these could be overcome by putting the number plates in different positions and making a slight modification to the front .suspension. On a 180-mile road trial its behaviour was again exemplary. It would be a most useful auxiliary for the builder or farmer whose work makes off-the-road operation as important as driving over normal hard surfaces.

I was agreeably surprised at the crosscountry performance, because although this model is based on the A70 car chassis, the pick-up carries much more load and does so without bogging down on soft ground or without anysign of damage to the engine base or other lower c4 parts when the wheels are deep in cart ruts.

With over 11 b.h.p. for every 1 cwt. of its gross weight, it has all the power required for a steady pull through soft ground or in sand, where rolling resistance is at its highest, and this provides a good performance on the road without taking a heavy toll of fuel. The four cylindered overhead valve engine developing 68 b.h.p. works willingly, and its torque at low speed, coupled with a low-ratio axle, is adequate for high traction at the wheels,

The refinements of the car----a synchromesh gearbox with steering-column control, a heating and demisting system and a full complement of instruments on a handsome facia panel—are retained in the pick-up, but it lacks an interior light in the cab.

Good Suspension

With a full load, the suspension is above average in its smooth riding and anti-roll characteristics, but running light the springing is inclined to be, harsh. . However, a pick-up rarely operates light; tricir.e often an overload is carried and the suspension has to be planned for maximum load and rough going.

The rear springs are controlled by double-acting shock absorbers, interconnected by a stabilizer bar, whilst the front wishbones have independent coil springs damped by double-acting shockabsorbers. Under the worst conditions of full lock and climbing a bank obliquely, the front wheels, with large-section tyres, scrubbed against the outer edges of the wings. This is a minor fault which could be rectified by fitting a packing piece under the rubber buffer, thus restricting wheel lift.

Remarkable Acceleration

The pick-up was collected from west London and driven unladen across town. In this form it had remarkable acceleration, even if the suspension made fast driving rather uncomfortable. With 12 gallons of petrol in the tank the pick-up weighed I ton 51 cwt. and a 15-cwt. payload was added to bring the gross weight, with crew, up to 2 tons 31 cwt.

The load naturally slowed the acceleration rate, but, even so, the Austin is one of the fastest 15-cwt. models produced in this country, and its pace compares favourably with that of many cars. After a short journey through south London, when I ,appreciated the smart acceleration and much improved suspension, I drove the A70 across some fields near Westerham and here the stability and sturdiness of the springing showed to advantage.

Gaining confidence in the crosscountry performance, .1 increased speed and, although there was some side-slip on loose ground, the vehicle was driven at normal road speed across rough sloping surfaces: Apart from the inadequate clearance of

the front wings, I could find no fault during this part of the test.

Then followed a hectic period in a chalk pit where the tracks were waterlogged, and the grey liquid-mass concealed deep ruts and holes below the surface. Often the wheels were partly concealed in the mire and the number plates scraped the .ground between. Apart from bending the brackets, there was no other damage.

In their present positions, the plates act as a guide t9t the driver, because if they were fitetd higher on the vehicle, the first warning of

_ insufficient ground clearance might besdamage to the engine sump.

The_sand pits were sodden, and the rolling resistance and tendency for the Wheels to sink, were less than if the sand had been dry. No difficulties were encountered there, even with„ the tyres inflated to maximum pressure, because the water had caused the sand to bind.

$.earby was Succombs Hill, the steepest road gradient in the county, which has proved invincible to many of the heavier and lighter commercial chassis. During the straight climb

• the A70 roared up and over the 1-in5 and 1-in-41 gradients with second gear engaged, and with the momentum gained there was ample power in hand.

Rich Mixture

The hand brake, a pistol-type lever mounted below the instrument panel, held the vehicle stationary at its steepest section. Bottom gear was required for the stop-start test, which was the first occasion of its use. The combined gradient and camber of the road upset the petrol level in the carburetter, causing enrichment of the mixture. This robbed the engine of its zest and careful clutch control was needed to make a start.

Having tried the Austin to the utmost, 1 prepared to examine its thirst and filled the test tank in readiness for the first consumption trial, which was staged over an out-and-return course between Coulsdon and Edenbridge. With its high power-weight ratio, the A70 is a top-gear performer and all gradients, including 1 in 20, were tackled without need for the indirect ratios.

Fast Worker

Although legally restricted to 30 m.p.h., it is much happier above 35 m.p.h., where the maximum torque is available. 1 kept to a limit of 40 m.p.h., which is still far below the normal cruising speed of the A70, and over the course the vehicle averaged 34.75 m.p.h. at a fuel-consumption rate of 24.4 m.p.g.

Because of ice on the road, care was required during a second test with a stop to every mile, and acceleration had to be controlled to prevent wheel-spin when moving away from rest. These precautions may have been responsible, to a small degree, for the economical fuel return of 20 m.p.g., which was obtained at an average running speed of 31.8 m.p.h., ignoring the 15-sec. stops.

This type of service is perhaps the nearest approach to short deliveries c6 of building materials, carrying loads into the fields and similar work, but a further test with 15-sec. stops, four to the mile, was made to represent retail delivery routine.

As the road surface was by this time becoming cleared of ice, greater use was made of the acceleration and deceleration capabilities of the pickup and this was reflected in the high average running speed of 25 m.p.h. The fuel-consumption rate of 13.5 m.p.g. is economical for the transport of a 15-cwt. load with frequent stops, and the ample floor space permits a bulky load to be carried.

The body is practically full-width, measuring 4 ft. 91 ins, across, and has a length of 5 ft. 5L, ins. The rear wheel-arches partially intrude into the body, and for many purposes this is an advantage, because goods can be stacked against the boxes to pre-vent movement, or two additional passengers can be seated.

I have already mentioned that the acceleration rate is well above normal for a commercial vehicle, and during the trials over 30 m.p.h. was cbtained in 8.2 secs. with second gear engaged, and after changing to a higher ratio, 40 m.p.h. was reached in 15.8 secs. from rest. Top gear gave lively acceleration from low speed, and 10-20 m.p.h. in direct drive took 7.6 secs., 10-30 m.p.h. 12.3 secs. and 10-40 m.p.h. 18.0 secs.

As the brakes of the pick-up and car are similar, the commercial version tends to develop reduced effective pedal travel and fade on long descents where the brakes are freely applied. Under normal conditions, there is more than ample retardation and this was proved by all four wheels locking for 33 • ft. in a stopping distance of 57 ft. from 30 m.p.h.

The stopping distance from 20 m.p.h. averaged 28.5 ft., Tapley readings of 65 per cent, being recorded. Hand-brake efficiency had already been proved during the hill trials, but as additional evidence it brought the vehicle to rest in 28.5 ft. from 20 m.p.h. on level ground.

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Locations: Austin, London

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