Opinions from Others.
Page 19
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Passing New Motorbuses.
The Editor, THE COMMERCIAL MotoR.
1,117] Sir,—One day last week. I noticed a new motorbus passing along a West-end street ; it was evidently on its way to Scotland Yard. It belonged to the London General Omnibus Co., as it was painted in that company's style. I have heard that considerable difficulty is being experienced in getting the new machines, which this company is reported to have built, "past the Police," on the score of undue noise. I have every reason to believe that the bus I saw last week was one of these new vehicles. If that be so, I should like to say that Scotland Yard, or its expert advisers, must be badly at fault. I have never observed a quieter-running commercial vehicle, and seldom have I met with a pleasure car—even of the highest grade —which could compare with this machine for that quality. Who is the judge in these matters F—Yours faithfully,
Harrow. WALTER WICKHAM.
Two-stroke Engines.
The Editor, THE COMMERCIAL MOTOR.
[1,118] Sir,Your correspondent " Rotax," in his letter on " Steam or Petrol? " in your issue of the 10th inst., draws attention to the claims of the two-stroke engine. Of the example he mentions—the American-built Chise1 have no practical experience, although I am aware that this make of truck bears an excellent reputation in their own country. Air-cooling, however, is not likely to make much headway in this country, and American commercial vehicles are not in the main suited to British conditions; they are essentially town vehicles, and designed for use under favourable circumstances.
There is little doubt but that the two-stroke engine presents considerable potentialities for industrial work. On account of its simplicity. The features that all valve gear is swept away, and that one cylinder gives as good a turning effort as two on the four-stroke principle, are factors deserving of consideration.
Two-stroke engines, for car and marine work, are by no means new, but early examples discredited the type by their excessive fuel consumption, and their liability to overheating. During the last few years, clever brains have been engaged on the problem, with the result that, to-day, we have several cars, and quite a number of motorcycles, fitted with engines of this type, and giving excellent results. The absence of parts requiring attention means that the conventional placing of the engine under a forward bonnet may be dispensed with.
Personally, I think there are distinct possibilities in a horizontal, two-cylinder, opposed, two-stroke engine combined with an epicyclic gear properly designed for heavy work. Such a power plant could be quite well slung beneath the chassis, with a final drive by side chains, or by a single 'chain to a live axle. Except far a dash radiator and driving seat, etc., the entire platform would be available for the load. A shorter wheelbase could be used, without overhang at front or rear, whilst the central disposition of the engine would give it adequate protection from vibration. Mounting the engine directly over the front axle is not good practice, yet it is difficult to do otherwise if a maximum of platform area for a certain wheelbase is to he obtained.
Any attempt at placing the usual type of engine beneath the chassis has heen foredoomed to failure, on account of the inaccessibility, but the only two points likely to require any attention on a two-stroke engine are ignition and carburation; both magneto and carburetter could be brought to the side, so as to be easily inspected. 1 had always honed that industrial-vehicle designers would he free from the conventions which have restricted—in some directions—the evolution of the plea-sure car, but, although they have not been bound by fashion, they have not. displayed ;try great originality. Slow progression is, ‘vithin limits, an excellent thing, but it would be very interesting to see a chassis built on the lines suggested. They are admittedly not new, but the great improvements made in the modern two-stroke engine render such a vehicle quite practical. Pre-ignition overheating, low power for weight and abnormal petrol consumption are no longer defects of the valveless engine, although it must be admitted that economy in fuel requires some improve ment. To compensate for this, however, such engines are adaptable to the use of paraffin, and thus present an opportunity for economy in another way. In any event,
the opinions of some of your readers' on the practicability of the horizontal two-stroke engine for commercial work, would, I am sure, be of great interest, and they might
prove of some service to those who have ideas in this direc tion.—Yours faithfully, GEO. H. CUTBUSH. 49, Jamaica Street, Glasgow.
Fire-Engine Tests at Glasgow.
The Editor, THE COMMERCIAL MOTOR.
[1,1191 Sir.-We notice a letter from Messrs. Merryweather, in your issue of the 3rd inst., regarding the fireengine tests at Glasgow on the 14th ult. Messrs. Merryweather, however, there make certain statements with which we cannot agree.
With regard to the engine powers of our machine and the Merryweather, we note that the Merryweather engine is made out as being very much lower powered than our own. We may say that our engine is a six-cylinder one,
with cylinders 5 in. bore by 51 in. stroke, and, by R.A.C. rating, this gives 60 h.p., not 77 h.p., as Messrs. Merryweather state; working out the power in a proper practi
cal manner, i.e., taking the total cubic capacity in inches of our six cylinders, it works out at 618.5 c. ins. total. The Merryweather is a four-cylinder engine, with cylinders
51t in. bore by 6,1i in. stroke, and the cubic content of this works out at 675.1 c. ins., i.e., their engine has 9 per cent. greater cubic capacity in es-hinders than our own. Fur
ther, Mes.srs. Merryweather seem to be under the impres sion that a six-eylinder engine of the same cubic capacity gives more power than a four-evlinder, but this, we may say. is not the reasou of our fitting our six-cylinder engine, but it is to give a more-efficient and more-reli able engine, with a better balance and a sweeter turning movement, together with less vibration.
There is one rather-interesting. point, in connection
with the Glasgow fire test, which we notice Messrs. Merryweather carefully ignore, namely, the result of the deep
lifting test in the Glasgow central fire-brigade station yard. In that test, we lifted the water from 28 ft., and
showed it pumping through the nozzle in 23 seconds. The Merryweather machine could not lift 28 ft. at all, and, in fact, did not lift the water until the level was raised to 23; ft.: in other words. had the Merrvweather been at a fire where they had required to lift the water from a depth below 231 it.. the machine would have been helpless, and would not have been able to assist in ex
tinguishing the fire at all.—Yours faithfully. HALLEY'S INDUSTRIAL MOTORS. LT , G. H. HALLEY. Managing Director. Yoker. llth March. 1910.
(We shall be happy to publish Messrs. Merryweather's views. They wish it to he known that they have never been able to get more than RI blip. Dom their engine. The comparisons between the three com
peting engines at Glasgow are N
R.A.C. rating ( -2-.5-)-Merryweather, 65 h.p.; Dennis and Halley,
BO h.p. each. (D 9) NA
13.51.31.T. formula 5 I-Merryweather, 654 h.p.;
Dennis, 73.2 h.p,; Halley, 726 h.p. LANCHESTER'S formula ('56 Al x N)-Merryweather, 54 h.p.; Dennis, 89 h.p.; Halley, 5611.p. Readers will note the variations with interest. In these fornuthe, the notation is as follows :-D, diameter of cylinders in ins.; 5, piston stroke in ins.; H, number of cylinders; and ft, the ratio of stroke to bore
stroke_mod bore.