Cost Cutter Gives 25. as an Oiler
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An Operator Installs a Four-cylindered Oil Engine In Place of the Cost Cutter Unit in a Thames 3-tanner Chassis, Using Fittings from a Basic Conversion Set : Economy is Notable, but Acceleration and Hill-climbing Performance are Slightly Impaired
A LTHOUGH the Cost Cutter ok. engine in the Thames 3-tonner is economical in comparison with the former eight-cylindered power unit, there are many operators who look for still greater economy, which is to be found only in an oil engine. British Insulated Callender's Cables, Ltd., transport department were responsible for replacing the Ford V8 petrol engine by a Perkins P4 four-cylindered engine in the ET chassis, and the new Cost Cutter 3-tormer has now been converted.
Interchange of Units
The B.I.C.C. transport department, of Erith, Kent, has achieved more than usual economy, because the four-cylindered units and parts removed in the conversion to oil-fuel operation will be used to replace the V8 engines in Thames 3-ton chassis already operated in the fleet.
To chassis have so far been converted and from experience of altering the prototype, the work has been timed on the second chassis to estimate the cost of future' conversions. The power unit used is the fourcylindered high-rated engine of 52 b.h.p. at 2,400 r.p.m. and 133 lb.-ft. torque, which is supplied complete with a Clayton Dewandre vacuum exhauster.
The front engine brackets are exchanged for those removed from the Thames ET6 petrol-engined chassis and tests are being made with Metalastik mountings used in con verting ET6 and ET7 chassis for Perkins engines. The front brackets are inverted for use in the fourcylinder oil-engined chassis and no additional drilling is required.
Another version of the engine forward mounting now under trial employs brackets supplied in the Perkins ET6 conversion kit and chassis outrigger brackets removed from the ET6 chassis and installed in an inverted position. This arrangement requires additional frame drilling.
At the rear the P6 conversion-kit clutch housing is employed to connect the P4 engine and Thames gearbox, together with a flywheel spigotshaft bearing and exhaust pipe also from. the kit. Slight alterations are required to connect the dynamo and starter wiring into the existing loom and the standard 12-volt batteries are replaced by heavy-duty units.
Additional Auxiliaries
A vacuum reservoir is connected to the exhauster and brake servo motor, and the existing accelerator pedal linkage is modified. Fuel and lubricating-oil filters are attached to the off side of the scuttle and the Kigass container is bolted on the opposite side.
As the Cost Cutter is wired for a 12-volt circuit, no alteration is required to the electrical auxiliaries when the P4 unit is fitted, but the 12-volt windscreen wiper, horn, petrol gauges and voltage regulator of the conversion kit are passed on to the ET6 chassis receiving the Cost Cutter petrol engine. The smaller 12-volt battery is also used in the ET6 conversion.
So it is estimated that the labour involved in converting the Cost Cutter amounts to 44 man-hours, made up of three hours for a fitter to remove the petrol engine, 32 hours to install the P4 unit, six hours to alter the wiring and three hours for welding.
Assuming that, with overheads, labour is charged at i is. per hour, the cost of conversion is £24 4s.; plus engine and material. The petrol engine removed replaces a V-8 unit which has completed its useful life, therefore the B.I.C.C. transport department does not have to dispose of the Cost Cutter engine, which in other organizations might add to the cost of conversion.
Comparative Tests The Commercial Motor participated in the prototype trials, which were staged over the same course as the Thames Cost Cutter road test reported in the previous pages. This prototype had the ET6 conversionkit engine mountings, which proved reasonably effective in isolating vibration from the frame.
The lower torque of the oil engine was noticeable in the steady gradient adjacent to Croydon Airport, which was just outside the capacity of top gear after starting from the airport buildings. This provided an opportunity of demonstrating the lack of vibration when pulling on full throttle at low speed and of showing that with an engine governed to about 2,400 r.p.m., there was sufficient overlapping in the gear spread.
Acceleration trials disclosed that the conversion vehicle was a little below the high standard attained by the Cost Cutter. Whereas with the petrol engine 30 m.p.h. can be reached from rest in second and third gears, direct drive is also required when the oil engine is installed, because the maximum speed in third gear is 28 m.p.h. It took 1 sec. longer (12.4 sec.) to reach 20 mp.h. from rest and at 29.6 sec. was 7.7 sec. slower in reaching 30 m.p.h.
The consumption trials were again conducted between Godstorie and East Grinstead, but the lower acceleration rate was here found to be of no disadvantage in maintaining a normal schedule. Over a 16-mile out-and-return route the converted 3-tonner averaged 27 mph. and used precisely 5 pt. of fuel, which corresponded to 25.6 m.p.g. Large savings will be effected in the contract work on which the Thames chassis are employed by 13.I.C.C.
A further test, for comparative purposes, was conducted with one stop to the mile. On this duty, the oil engine performed efficiently to give a return of 19.65 m.p.g. Although the fan was removed and the radiator was partially muffled, the water temperature remained low, a maximum reading of 149' F. being recorded, against 57' F. ambient. Steps are being taken to raise the coolant to a more efficient level.
Unladen Weight Difference
The gross laden weight of the oiler during this test was a little higher than that of the petrol-engined model, because the converted unit has a kerb weight of 2 tons 7/ cwt., giving a total laden weight, with crew and equipment, of 5 tons 11 cwt. This does not cause tyre overloading because the weight is evenly distributed with under 2 tons on the front axle and the 6.50-20-in. tyre of eightply rating is advocated for a 1-ton 2-cwt. load.
In its hill-climbing performance, the conversion appeared to be slower than the standard model with petrol engine, and although earlier gear changes were required on the test gradients, there was no need to employ lower ratios. If the oiler were continually operated in a hilly area with full toad, the difference in performance would be noticed, but, as seen by the consumption-test results, in general service it would keep pace with a standard Cost Cutter petrol-engined lorry.