Problems of the
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HAULIER
AND
CARRIER
Types of Oil Engine. Running Costs of Oil engined Buses
ESPECIAL interest is lent to the subject of the present series of articles by announcements which are appearing concurrently regarding the activities of oil-erigiiie makers, such as L. Gardner and Sons, Ltd., the Associated Erquipment Co., Ltd., and John rowler and Co. (Leeds), Ltd. The A.E.C. concern pro,duces now a new model of its oil engine, which was shown at the annual meeting of the managers' section of the Municipal Tramways and Transport Association last week. It now develops 130 b.h.p. in its six cylinders of 115 mm. and 142 mm. bore and stroke. As the technical description shows, this 130 b.h.p. is developed at slightly over 2,000 r.p.m. and 140 b.h.p. is reached at 2,500 r.p.m. with a fuel consumption of less than half-apint per b.h.p. per hour. The weight of this engine is only 1,400 lb., which is equivalent to 10 lb. per b.h.p.
The Fowler engine, although not capable of such high Speeds, nevertheless has many interesting features.
The latest Gardner LW engine, described in this issue, is light, refined and economical.
Reference to these matters reminds me that I have not yet dealt with certain queries which have been pt to me relative to the types of engine on the market, particularly as to whether one form is more suitable to the hauliers' purpose than another. As a general rule I prefer to take the line that purely technical questions are outside my scope as not having any direct bearing on the operation side of commercial-vehicle work, which is my concern. I can, however, without much expenditure of time or space, give readers a line of thought which may he of assistance to them in coming to a decision on the matter. Considering the subject nontechnically, the most obvious difference between the two classes of engine now in use is that of speed of rotation. The A.E.C. is almost in a class by itself in
being capable of being revved up to 3,000 r.p.m. The 141XiDDIM speed with any other is about 2,000 r.p.m. and the normal speed is, as a rule, round about 1200, r.p.m., as compared with the 2,000 r.p.m. of the A.E.C.
The other point of difference is in the method of starting. The high-speed engine usually carries an electric starter and requires the use of electrical heating plugs for starting. The other type may have an electric starter but does not utilize external means of heating. Generally a number of the cylinders is put out of action for starting and one—at half compression —provides the start, being swung by hand in the ordinary way, using the handle..
Now, so, far as my observations go, and according to the experiences of hauliers with whom I have come into
contact, there is very little to choose between the two types. For rough haulage work, perhaps, the slowspeed engine is really as good as any other. It really starts quite easily and its moderate rotational speed is DO disadvantage. It is used also for passenger work.
Now to return to a consideration of cost of operation. In the previous article (published September 8th) I dealt with goods-carrying vehicles. This week I give figures for motorbuses. The method oi arriving at the figures is very much the same as that described in the other article. I must refer readers thereto for details. Slight differences in the actual method of arriving at the figures arise from differing conditions. The cost of maintenance, for example, will not be in proportion as much more in the case of an oil-engined bus as it was in the case of a goods vehicle because in the figures for maintenance of buses there is a bigger proportion involved in upkeep of coachwork. That is, of course, net affected by the oil engine.
In the case of the items depreciation and interest on first cost, too, the percentage increase is not so great because, whilst the increase in cost of the complete vehicle may be the same, the total cost of a bus is so much greater than the total cost of a goods vehicle that the percentage increase becomes less.
I only need to add the customary warning, that these figures are in no sense of the word arbitrary. They are, in the first instance, based on averages; therefore they are capable of improvement under favourable conditions and equally likely to be increased under un
favourable conditions. S.T.R.