THE YORKSHIRE OILER
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-FASTED IN THE PENNINES THREE main considerations lay behind the policy of the Yorkshire Patent Steam Wagon Co. in producing the oil-engined goods vehicle which was seen last November at the Olympia Commercial Motor Show. One was the technical progress of the oil engine. the company having preferred to wait until design became steady and maintenance figures had been established at a low level. The second was the question of taxation, the 1933 Budget announcement giving the answer that had been awaited. The third was the possibility of employing, in conjunction with the oil engine, a preselective gearbox that could be thoroughly relied upon.
The vehicle exhibited at Olympia has, in the intervening months, been subjected to rigorous trials, in the course of which it has covered 5,000 miles. As the result of this L no important change has been suggested. The Wilson gearbox was dismantled at the end of this period by the maker, the E.N.V. Engineering Co., Ltd., London, and no replacement was found to be necessary. We are informed by the E.N.V. concern that it was in every way satisfied with the way the gearbox was standing up to arduous demonstration work in a heavy commercial chassis.
Two Unusual Features in the New Vehicle.
Unorthodoxy of appearance and transmission system are the features of this new machine which first attract attention, and the interest in this road test, of course, centres around the performance, viewed from every angle, of the new transmission.
From the driver's aspect, the aim of providing a control so simple to work that steam-wagon drivers can, without difficulty, change to the new machine, is, we may say, achieved. The control is very easy indeed to operate. Any desired gear is preselected by means of the small finger-operated lever on the steering column and is engaged by pressing the pedal provided, with the left foot, this taking the place of the ordinary clutch pedal.
The epicyclic gears are constantly in mesh and are engaged by self-adjusting friction bands, so that whilst a judgment of relative gear speeds is still a useful factor in the making of a good driver, the care that must be exercised in engaging rotating gears is not necessary, The really bad driver is thus capable of getting along moderately well with the vehicle, for the gear is designed to withstand quite a fair amount of abuse.
Quick Manceuvring and Security in Traffic.
It is not necessary to say much more about this feature of easy control for every reader who has driven motor vehicles will appreciate the benefits of constant mesh and friction engagement. We may stress, however, that for manceuvring fore and aft in confined spaces the Wilson gearbox reduces trouble, also that it gives a. sense of security in circumstances of traffic, especially on hilly roads.
More important, to our way of thinking, are the effects on the general efficiency of the vehicle. The very fact that the driver is not tempted to minimize gear changes means that the engine is working at efficient speeds for a bigger proportion of its running time.
Whenever road conditions show that a gear change, up or down, is about to become necessary, the driver moves the preselector to the desired gear, and, feeling confident that a tap on the pedal will ensure the engagement, he is free:to choose thepropitious moment for making the change.
In particular this is appreciated in hilly country. With this in mind we chose for the main run of the day a route which was more than normally difficult, going from Leeds across the Wharfe Valley to Harrogate and then over the main Pennine watershed through Blubberhouses, turning south-east again at Bolton Bridge and reaching Leeds via Ilkley and Otley.
From the fuel-consumption point of view it might be taken as fairly representing the class of work hauliers have to undertake in that part of England, but from the point of view of the transmission it gave a particularly good chance of testing performance.
Using the Correct Gear for the Gradient.
In really hilly country one meets with a large proportion of climbs which the lorry would negotiate on second gear if only one could make the change from first to second gear without losing road speed. With the preselective gearbox one can effect such changes and make use of the higher gear.
Fuel consumption is a reliable measure of efficiency, and the fact that we obtained on this 61.6-mile circuit a figure of 12 miles per gallon ,of Light Diesoleum is, we think, sound testimony in this regard. On a long mainroad run probably 14 m.p.g. would be averaged. The test was made by first filling the tank to the neck of the orifice and then refilling with careful measurement after completing the journey and parking the lorry in precisely the same position on the works floor.
The take-up of the drive in each gear was not so smooth as it should be, but this appears to have been due to slight maladjustment following the recent dismantling of the gearbox, for we were assured by the Yorkshire company that the symptom was a new one, and by the E.N.V. concern that it was not a frequent trouble and could be corrected by adjustment.
The reluctance of the oil engine to lose crankshaft speed when the foot is removed from the accelerator pedal causes considerable work to be put on to the friction faces of the gearbox and makes the test driver feel that serne simple means for slowing up the engine might be an all-round advantage. This is stressed by the ease of changing down as compared with changing up, the latter requiring a long wait to ensure a smooth engagement.
Certainty of Gear Change in Emergency.
With friction engagement, however, one is always sure of being able to make a quick gear change whenever necessary, irrespective of this question of engine speed. That accounts for the brief pauses shown in our acceleration graph, the performance in this case being obtained with a certain amount of snatch. The snatch was noticeable when starting from rest on a gradient, and such restart tests were made on gradients as steep as I in 6.
Considering further this subject of gear engagement, it is to be noted that the top-speed cone has a friction area of 33 sq. ins., but that it is called upon to take only a proportion of the engine torque. In the case of the
fourth and third gears the friction-band area is 50 sq. ins, and in the case of secoud, first and reverse gears the area is 39 sq. ins.
The E.N.V. concern states that the particular gearbox employed on the Yorkshire vehicle is of more than ample torque capacity to suit the torque of the engine without it being necessary to interpose any form of clutch between the two units.
As for the power of this vehicle, it is sufficient, even with the full 7-ton pay-load, to give a performance which
will allow an average speed of 16.1 m.p.h. to be maintained on a hilly journey such as that of our fuelconsumption test, and on long level stretches a speed
well over 30 m.p.h. can be attained with ease.
It is difficult to state the maximum speed because above 25 m.p.h. -the acceleration is naturally not marked, but the fifth gear is unquestionably a great advantage
in keeping up the average on a long run while maintaining a low engine speed. Also, of course, it is a great help in hill-climbing.
The main hill-climb test was the ascent westward on the Blubberhouses-Bolton Bridge road, which rises to an altitude of 1,000 ft. A climb 1i mile long leads to a summit at the twelfth milestone from Harrogate.
This required the continual use of second gear, the road speed averaging 8 m.p.h. The engine pulled manfully and without vibration (it is rigidly
mounted in the frame) and we were not surprised that the
radiator water boiled as we neared the crest. The air tem
perature was 48 degrees F., but there was a following wind. Later in the day we climbed Gleclhow Lane, Leeds (1 in 7) in first gear with plenty of power in band. The water temperature in normal running was 150 degrees.
On this 1-in-7 gradient we demonstrated that either foot brake or hand brake easily held the 114 tons, and would arrest the vehicle when moving. The vacUum reservoir, acting through one large Dewandre cylinder, gave six good applications after the exhauster had been stopped, and even without vacuum assistance the foot 3510 brake securely held the vehicle on the same incline. On the level road the brakes proved correspondingly efficient, as our graph indicates. There was an absence of time lag in the working of the servo, also a complete freedom from squeaking.
The vehicle tested had Marks steering gear which was light and slightly self-centring, but not quite irreversible in action. The turning circle is commendably small, the wheelbase being 12 ft. 4-hins.
The other controls are all convenient except the ac celera,tor pedal, the vertical shaft of which, however, has been replaced in production models by a more comfortable arrangement. The cab is roomy and the engine housing keeps fairly cool, although it might be improved by thorough lagging with sound-deadening material. The springing and lateral stability of the laden lorry are good. The front panel of the cab is a unit hinged at its top edge, and when raised gives access to the wiring side of the instrument board, also to the radiator block and the forward engine auxiliaries. A bulkhead trapdoor in front of the mate's seat has the tool box attached to its anterior face—a highly practical arrangement Removal of this trapdoor facilitates reaching the engine from the -front. The front chassis cross-member is tubular and detachable, enabling the power unit to be removed forward.
This new cab design strikes one as excellent in every way. The gearbox is separately mounted so that it can be lowered and there is a floor trapdocir to facilitate this, Drake adjustments are all accessible.
The Yorkshire oil-engined vehicle is a new model designed without need for conforming to a prototype, and its first 5,000 miles of road -trials have shown that its unorthodox features have distinct possibilities.