A Coal Consumption Test.
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A Comparative Test Between a Rubber-tired and a Steel-tired 5-ton Tractor.
A coal consumption test does not at first sight appear to offer much scope to the journalist in that it would appear to be somewhat barren of any interesting copy. In the particular instance to which we are about to refer there are two other reasons which would to a greater extent, militate against our being able to make this test interesting reading. In the first place the experiment was only a rough one with the object of comparing the amount of coal used on a steel-tired tractor with that used on a similar one fitted with rubber tires. In order that these results might be as useful as possible it was also arranged that the same journey should be undertaken in each case. Consequently, as the only measurements to be made were those of the. coal used on the /load, and as there were no special arrangements being niade either for this or for ascertaining the amount of water used, or oil, we are, therefore, unable to interest our ultra:scientific friends by a description of any apparatus or special methods.
The second factor was that the machines under test were the property of J. Lyons and Co., Ltd., and our readers may remember that, it, is but a short time since we devoted some little space to a description of a portion of its motor transport. We are therefore precluded from making much copy under this head. Nevertheless, at the present three, a 40 or 50-mile run through a country which is at war, and where every different locality has its own particular and special activities relating to the production of munitions, of the training of soldiers and other preparations of a like nature, is not without interest.
Well-known Type of Tractor.
Both machines were of the same type, being the well-known Aveling and Porter compound steam tractor. It should be pointe& out that these machines are fitted with the Relpaire firebar and work at a pressure of 200 lb. per square inch. One of these, called, for want of a better term, the " steel-tired " one, has the usual metal-rimmed front wheels, the rear ones, however, having composite wood and rubber inserts; the other machine differed in respect of the rear wheels, on which the patent MacintoshColeman, triplex, non-skid tires, 1530 mm. diameter, 399 mm. wide over all, were fitted. Each tread is made upof three bands, the outer ones of which are hard rubber, the inner one being much softer, and, owing to its extra resilience, this centre one always stands higher than the others, when not under load, and when loaded a larger area of its surface comes in contact with the ground. When we saw them, these tires had run about 2000 miles, and, although the outer bands were in firstclass condition, the inner ones were considerably cut about.
First Journey on Wheels with Nom-skid "Inserts."
Our first journey was to be made on the " steel-tired" machine. We were informed that the loaded trailer would start out at 9 a.m. prompt, _but, as we expected, we had to wait an hour and half before we set out.' We were informed that this was owing to the fact that our request that the coal might be put up in half-hundredweight bags for convenience in weighing, had been overlooked and the work of so dividing it had still to be done. In the meantime, while this was going forward, we had the pleasure of a stroll round the" yard, and as vehicles of al1,kindf3 were loading up, being checked out or making their departure, there was much to see of interest to the commercial-motor expert.
• Lyons' Catholic Taste.
The first thing that struck us was the catholic taste, if one may put it that way, evinced by Lyons in the selection of their fleet. Every branch of haulage is represented. We observed a pairhorse-drawn van cheek by jowl with a five-ton Foden lorry, and along one side of the yard, which has been specially arrange(' for the purpose, a row of electric vehicles. Arrangements have been made for these to be charged at the same time as they are being loaded. The machine with which we were about to journey constituted a fourth variety. Petroldriven machines were also on view, and up a side alley we discovered an almost unique specimen in the way of a petrolengined vehicle with hydraulic transmission. To the uninitiated we may describe this as being an ordinary petrol lorry as regards its engine and frame, but that in place of the gearbox will be found a set of pumps. These transfer fluid to turbines, or water-motors, which are situated in the rear road wheels. Different speed ratios may be obtained by altering the relative pressure and flow of the fluid from pump to turbine.
Over I lf Tons Total Weight.
At ten minutes past ben we were ready to set out. The coal on board was 7,i cwt. The weight of the tractor ready for the road was 6 tons 13 cwt. 2 qr., the gross weight of the trailer 4 tons 17 cwt. 2 qr., so that it will be seen that the total moving weight was 11 tons 11 cwt. The tare of the trailer being 1 ton 9 cwt., it is evident that the useful load carried was only 3 tons 8 cwt. It was unfortunate that on this occasion, the net load should be so much below the capability of the tractor, as this, of course, must inevitably.militate against a very good result being obtained in respect of low coal consumption for weight carried. Another factor which told against the tractor was the condition of the tarred roads, these, owing to the heat, were soft and dragged considerably.
Two Lines of Trams in a 20 ft. Road.
Our road lay by way of Hammersmith, Chiswick, Brentford Bridge, Isleworth, Hounslow, then through Bag,shot, Farnborough, Aldershot, and Farnham. There was little of incident until we arrived at the narrow stretch of roadway just before crossing Brentford Bridge. This road did not appear to be more than 20 ft. wide, but was, nevertheless,' occupied by tWo lines of tramways and' frequently also by two' lines of trams. The-road surface over the bridge was, as usual, hp. It is rumoured that when one line Of tramrails is not being repairedthe workmen find something to do with the other !
A Ditched Steamer.
After this, as traffic became thinner. progress became a little more rapid, we eyensoccasionally exceeded the speed limit of 5 m.p.h. At.Isleworth we made the first stop of the day, and we gathered that this was the,first meal for the driver. since a very early hour. of the morning.. We then pushed on until we got to Staines at a quarter to one o'clock, where we took advantage of an adjacent horse-pond to ta,ke in a little water. This occupied nearly a quarter of an hour, and advantage was taken of . this period for a little cleaning and oiling as well as firing up, and the transference of three sacks of ,coal from the rear of the trailer to, the bunker of the tractor. We got away again at one o'clock and continued our journey to Sunningdale, where ths second stop for water was made. Somewhere between Sunningdale and Bagshot we passed a steam wagon, which had evidently lost some portion of its steering gear and had been brought to rest in the ditch at the side of the road. Just about here, approaching Aldershot, evidences of military occupation became more frequent. We passed on the way a small Daimler lorry carrying a stock of aeroplane"
_ spares. Later on a MeCurd salvage A46 machine was observed in attendance on another army three-tonner which was evidently suffering from rear-axle trouble.
"Some" Tractor Driving.
Just before entering Farnborough we came up with a large field gun section and, as this was-of some length, we were, unfortunately, compelled to remain behind and continue in that position until we came almost to Aldershot,. Eventually, just before arriving at the lastnamed place, the men came to a stop and, the road being at the time clear, we made a dash to get past .them. On nearing the other end, however, we found a Foden with trailer had entered on a similar sprint, with the result that we were able to witness some very clever manceuvring on the part of the driver of our own tractor, who, with very little more than the width of his own machine between the frightened horses and the other lorry, nevertheless managed to get by. Having made the passage successfully, and put the slowly moving train behind us, we proceeded on our way with some slight increase in speed. A little further on we passed the overturned motorcar which was illustrated in nearly all the daily papers on Tuesday, the 27th July. Just about here also we were passed by a couple of Crossley army wagons, each pulling a two-wheeled trailer conveying aeroplane wings' and we were considerably surprised at the rapidity with which these trailers can be hauled and their ease of handling. From there to Farnham the run was practically uneventful and at the latter place we concluded our journey and observation. We had travelled in all a distancsi of 35 miles and had remaining on the back of the trailer five half-hufidredweight bags of coal, •with another half hundredweight still in the bunker. We had, therefore, used 4 cwt. or 476' lb. This is equivalent to a consuniption of 13i lb. per mile, equalling 1.18 lb. per ton-mile of gross load moved.
. . . .
The Second Journey.
Our second journey was made under weather conditions somewhat different to
those of the first. The morning opened bright and clear, but before we were able to start, these conditions unfortunately had altered considerably, and a heavy thunderstorm, in addition to laying the dust and affecting the road surface, also led to a drop in temperature, so that the tarred road surfaces were not softened to the extent that they were in the first day. The tractor, in the early morning had shown signs of leakage, and it had become necessary to take out a fusible plug seating and replace it. As is frequently the case, this turned out to be a much longer job than was anticipated. It should be noted that the tractor, which is fitted with rubber tires, is the oldest of the three employed by Lyons, and is suffering to a certain extent from the inevitable effects of advancing years. As a matter of fact, the fitting of the rubber tires was in part intended to alleviate the effects of vibration and with a view to lengthening, as far as possible, the life of the machine. It is interesting to note, also, that this tractor had, for a week or 30 before our test, been in the repair shop having new tubes fitted, and that these were held in position by means of Barron expanding ferrules, which are rapidly becoming the standard fitting for this purpose. Eventually we got going at 2.40 p.m.
Total Weight 1l Tons.
The amount of coal carried was 7.1 cwt. This, in addition to the weights of tractor and loaded trailer, which were 6 tons 12 cwt. 1 qr. and 4 tons 16 cwt. 3 qr., respectively, brought the total up to 11 tons 16 cwt. 3 qr. It will be gathered that the gross tonnage was very little different from that of the first trip. The route taken was the same as that previ-, ously, and was to a considerable extent devoid of interest. Passing through Isleworth, we saw a large convoy of Armymotor lorries, which was chiefly remarkable, for its varied composition. It included amongst others. Pierce-Arrow,Peerless, Locomohile, F.W.D., Daimler, L.G.O.C.; Commercar and Dennis vehicles. The running of the rubber-tired machine was undoubtedly much easier
than that of the steel-tired, as might no doubt be expected. This was particularly noticeable on the rough stretch of road between Staines and Egham. Up Egham Rill the road was very slippery indeed, but it was interesting to note that the tractor did not suffer at all from this cause. Rather higher speed is evidently possible with rubber tires on the whole. As the coal-consumption resets will show, the economy in this clirectim is worthy of serious consideration. We eventually left the machine just beyond I3agshot. The distance travelled under our observation was therefore 24 miles, the coal consumed being 21, cwt. or 252 lb. From this it is easy to calculate that the coal used per mile was 101 lb. or .:1 lb. per ton-mile, as compared with 1.18 lb. on the " steel-tired " machine.
Some Figures from Lyons.
The following figures, which were obtained by the foreman driver employed by Lyons, are interesting for purposes of comparison with our own results. They were obtained on the same rubber-tired tractor as that which we ourselves used, the journeys, however, being in the Birmingham and Liverpool directions. In the course of the journey to Birmingham, the driver took the Bull Ring Road, which traverses a very steep hill., and he reports that there was no difficulty at all in climbing this with this tractor, although 84 a rule it is avoided by steeltired haulage machines.
The actual coal-consumption figures are given for a return journey London to Brighton with 8i ton (trailer) on the out ward journey, and 5 to 6 tons on return. ' The actual consumption was 91 cwt.,.
roughly, 11 lb. per mile. He reports that% previously, with steel 'tires, the best con-' sumption was 14 cwt., approximately 151 lb. per mile, under similar circumstances of weight and road surface.
These figures are, of course, only approximate, but, for comparison purposes, they clearly indicate that rubber tires directly make for economical consumption.
Pickford's Evidence Corroborates.
With a view to ascertaining the experiences of other users we called upon Pickford's, Ltd., and gather from Mr. Elliott that the company's experiences in this direction bear out those of Lyons.
Previous to the outbreak of hostilities, the company had a similar Aveling and Porter tractor, fitted in this case with Continental solid band tires, on both front and rear wheels, single 900 mm. by 120 mm. on the front, and twin 1500 mm. by 120 mm. on the rear.
5700 Miles Tires Almost As New.
The mileage rim by this machine before
by was taken over Y the Army authorities was 5700, and the original grooves moulded on the surface of the tire were still in evidence.
Although Mr. Elliott could not provide us with any definite figures he, at the same time, was of opinion figures, considerable economy in coal consumption was effected, and he also stated that the
drivers found that they could run 20 miles without taking in water, instead of as previously from 12 to 1.4 miles only. There is no doubt that the fitting of rubber tires to such machines has also the effect of easing the vibration and of lessening the effect which travelling over rough roads has on the mechanism. Pickford's representative state that, owing to the fact that the driver finds it much more comfortable to run with these tires, he is likely to speed up and work the engine to its limit. The result of forcing a machine of this class is, of course, detrimental to boiler and mechanism.
Not for Universal Application.
Other factors which must be taken into account in considering the advisability of fitting tractors with rubber tires, especially in the case of contractors such as Pickfords, Ltd., is the variety of work which the machines are liable to be called upon to tackle. For fast work on town and country roads, Mr. Elliott thinks that such tires would prove their worth, but where—as is frequently the case—a machine may be occasionally called upon for farm work and work in the fields, these tires cannot be fitted, as they prevent the addition of the spuds or strakes which are generally necessary when working in soft ground. He was strongly of opinion, however, that where a fleet of some half-dozen or so tractors is kept, at least one—or probably two or three of them, according to the class of work to be met with, might vary well be rubbertired.