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32.8 m.p.g. with 1-ton Load

26th February 1954, Page 148
26th February 1954
Page 148
Page 149
Page 150
Page 148, 26th February 1954 — 32.8 m.p.g. with 1-ton Load
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by Laurence J. Cotton.

BY judicial selection of transmission ratios, the designer of the Dodge 3-tonner has provided a degree of fuel economy above the average while retaining a reasonable performance in respect of hill climbing and acceleration with full load. The return of 32.8 . m.p.g., when carrying 3i tons, sets a high standard, but if the Dodge is operating in flat country it might be possible to improve on this because part loads would possibly be carried on return journeys. From its acceleration rate the chassis is not over-geared for economical part-load work.

Although its economy is a keynote there are other likeable characteristics about the Dodge 3-tonner. The engine mounting, for instance, is as nearly perfect as I have yet met and in addition to smooth running the unit is well insulated in the cab iron) the sound and heat angles. The degree of engine noise noted in the cab is no greater than that of a normal-control model.

The mounting arrangements of the Perkins four-cylindered engine and Unit-mounted gearbox, include a Metalastik sandwich component below crankshaft level at the front en, and bonded units, in compression and shear, adjacent to the clutch housing.

The engine is a " non-exhauster " type and fits snugly into the chassis, requiring only slight modification to the standard cowling in the cab_ There is a slight bulge at the rear of the cowl to clear the cylinder head. The engine is the high-rated version, being set to give 55 b.h.p. at 2,400 r.p.m., and has an 11-in.-diameter clutch, making for prolonged service before requiring adjustment. There is nothing unconventional in the chassis, which is built with sturdy components and planned for good weight distribution between axles. Although having no vacuum servo, brake-pedal operation is reasonably light and on a good concrete-surfaced road I found that emergency applications brought the vehicle smartly to rest with a tendency to lock all wheels.

My test of the Dodge was spread over 125 miles. The starting point was the factory at Kew where a payload of concrete blocks was added and well battened down against movement. The vehicle was the normal-wheelbase chassis with art 11-ft. 6-in, drop-sided body, but there is an alternative model, of 13-ft. 9-in.wheelbase which accommodates a 15-ft. body.

After leaving Kew the first objective was Harrow Hill. There are several gradients leading up to the school, including a 1-in-9 section on Grove Hill, which was climbed in second gear at 8 m.p.h. Then followed a steeper trial on George Street where the Dodge was pulling well in second gear until traffic caused an enforced stop on the 1-in-5i section. Starting from rest at this point, with the front wheels on full lock, is no mean task but no difficulties,were encountered and the transmission take-up was smooth.

From Harrow I drove to Bagshot, my initial impression of its good behaviour in traffic being later confirmed when getting through Slough and Windsor. Here the roads are narrow and progress was further hindered by parked cars and lorries. On the main road between Harrow arid Slough the Dodge was put through its paces and a governed speed of 42 m.p.h. was recorded.

Consumption Trial • At Bagshot the auxiliary fuel tank was connected to the injection pump for economy trials to Farnham and back. In addition to undulating ground, the first trial-, which was intended. be non-stop, ,waS hindered by a min..hold-up in Farnborough, and later by two,tratliczlight delays. Altogether, in a 9-mile run, the engine was idling for 1 min. 40 sec.. with the vehicle at rest.

Occasional use had to be made of the indirect gearratios, and the Dodge did well to make a return of 24.425 m.p.g. at an average running speed of 27 m.p.h.

A second out-and-return run, with one stop to the mile, afforded a fuel consumption rate of 22.3 m.p.g. In making a hasty change from third to top gear, I inadvertently pulled the lever over the " gate " to reverse. This was not an isolated mistake, and I would prefer to see a higher step, or a stronger spring for positive lift on the gear lever, to engage the reverse ratio.

Initial Stiffness

This is my sole criticism of an otherwise excellent vehicle. The fact that the chassis was new and the initial stiffness was still apparent in gear changing, tended to aggravate jumping the gate. It is understood that a stronger spring may be fitted.

From Bagshot the Dodge was driven to the Heathrow circuit for further consumption trials over ground which would compare with operation in Fenland. Cyril Kent, representing the engine makers, was my driver for this test, and, apart from the traffic-light delays. the vehicle was kept at a steady 30-35 m.p.h. on the 1217-mile triangularshaped circuit. The axle ratio was well suited to such work and only 3.1 pints of fuel were used on the first lap, corresponding to 32.8 m.p.g. and at an. average speed of 29.4 m.p.h.

A second trial, with one-stop-per mile to represent local service operation, was staged over the same course and here the Dodge made a return of 26.7 m.p.g. Such economy, is exceptional. The axle ratio of 5.85 to 1, in conjunction with the engine power available, will ensure even greater economy with reduced. or no payload.

The acceleration and braking trials came afteryver 100 miles' work, and at a period when the drums were

warm following spells of ?milk driving. from .20 m.p.h. the lorcy came sharply to rest in 21 ft without excessive pedal pressure or wheel locking.

This standard of retardation Was retained from 30 m.p.h., but here the tyres marked the road heavily. and there was a tendency 'towards wheel locking at both axles. I do not consider ther& is any need for a. servo with the present braking gear provided.

The acceleration tests indicated average performance for an oilengined chassis. From rest to 30 m.p.h. occupied 38.6 sec., and the direct-drive test from 10-30 m.p.h., 42 sec. Undoubtedly this is slower than the performance of most petrolengined lorries, but I would not suggest improvement on this at the cost of fuel economy. Drivers will have to be educated to accept this standard, especially if they are changing from a petrol-engined 3-tonner equipped with a unit which might also be common to a 5-tonner.

Although tested M sunny weather there was a stiff, cold wind blowing, giving a day temperature of 49° F., and the radiator water temperature remained low. In general driving the water temperature was 115°F,, indicating that partial blanking of the tube stack might have been beneficial.

I have mentioned that engine-noise in the cab was well modulated, and this applies to the heat insulation because the cowl projecting into the driving compartment was cold at all times-as were the crew, the windows being wound up and the air vents closed all day.

In its steering and riding characteristics the Dodge stands high in my esteem, and I liked the position of a24 the long gear lever, which is sited close by the steering wheel. After more than 120 miles, alternatively driving and observing, I felt no suggestion of tiredness, and, as measure of the economy of the Dodge, the fuel-tank gauge wavered about the full" mark at the end of the day's work although about half the mileage, including the hill climbing, had been covered on the main supply. I would suggest that a smaller tank might meet the needs of a 2-3-ton lorry of this type.


Locations: Slough, Windsor

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