OPINIONS FROM OTHERS.
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The Editor invites correspondence on all subjects connected with the use of .commercial motors. Letters should be on one side of the paper only and typewritten by preference. The right of aboretiation is reserved, and 92.0 respotisibility for Mews expressed is accepted.
Cable v. Tractor Ploughing.
.2;he Editor, Tim OoviumaiAL MOTOR.
[1560] Sir,—In view of the urgency of more acreage being ploughed this season for a greatly-increased corn harvest in 1918, and the urgent and almost tearful appeals to farmers for bigger efforts, it would be instructive if youor the readers of your paper could tell me why the W.D., through the A.S.C., are using very large Fowler 10 h.p. nominal steam ploughing engines, brand new, and 'fitted with cable gear and rope complete for cable ploughing, for the purpose of hauling baled hay or clover straw to stations with rarely more than a five-ton load, occasionally on A.S.C. horse vehicles?
These engines are yery urgently needed in this district for ploughing, and there are several men in this particular locality patiently waiting delivery of sinlilar engines from Messrs. Fowler. Engines of the size in question are ideally suitable for ploughing in the small fields which pertain in these parts' and are niO're suitable than the larger ones for the time of the coming year. Their light weight (except Fowler's big 14 h.p. and 16 hp. nominal engines) would not cut up the land so much.
I must add that an ordinary five-ton tractor in private users' hands will probably do double the work these big engines are doing, and cost one half the money to buy, using less than half the steel plate, besides operating at one-third the cost with not a tithe of the damage that these big engines do to the roads.
It is a great pity that a quarter of the money spent on tractor ploughs had not been spent on these steam ploughing sets 4for PLOUGHING when we might easily have ploughed the acreage asked for, and without necessitating the importation of fuel from abroad.
—Yours faithfully, CONTRAcToR, Halstead, Essex.
" Some Bus."
Tire Editor, THE COMMERCIAT :VICTOR.
[15611 Sir,—We attach herewith the copy of a letter sent by a customer of ours to a well-known insurance company. We consider it excruciatingly funny, and suggest that you publish it, if only as a ..tribute to the manufacturers, Messrs. Dennis Bros., Ltd.
' The L.G.O. Co. must sit up and take notice.—Yours faithfully, FEATICERSTONS (LONDON AGENTS), LTD., G. T. HUNT, Director.
• (copy.) Dear Sir,—Re insurance on the lorry that Messrs. Featherstons are supplying to me. As I have agreed to buy it right-out, Messrs. Featherstons will have no right to insure it with you or anyone 'elseat present.
I am not intending to insure it, and if I was I should insure it with the — company, as that is the company that my other car is insured in for fire. I cannot, however, see the use of insuring it against anything else in any company, as you all state that the insurance is void if overloaded. Well, as a matter of fact, my car is overloaded 99 times out of a 100. The ear is a twin-cylinder Dennis. The makers class it as a one-ton van. I have from 30 cwt. to 2 tons on her. For instance, I have seating accommodation for 17 persons inside, with room for /2 eat. of goods. You see, she is already overloaded now. I often (especially in the summer) get 22 inside. They sit on each others' laps or on the bags of sugar or cases of soap, or whatever else there happens to be inside. When I cannot cram another inside, I put them on top by means of a ladder, getting the women on top first and carrying the babies up to them afterwards. I have had as many as 13 on top, including the children, and two men on the bonnet of the engine. The passengers do not care how or where they ride 60 long as they get on the car. Country passengers are not like Londoners. They don't keep grousing because there isn't any room. Any passenger will offer her lap to another. My passengers are nearly always women.
The machine was nine years old when I bought it, arid I have run it two years without accident at present, and it has not been in the garage for more than four days, and that was the fault of the garage people breaking a part of the magneto in dissembling it, and they had to send it away for a new part. Under your system of insurance, by what I can see, for a country carrier to insure, in plain English it would cost him h—I and all, and then when an accident occurs there would be the quibble, "Oh! you are overloaded ;we can do nothing for you."—Yours, etc.
[Owing to the gift of vivid humorous imagination possessed by this correspondent, we wonder if be would favourably consider a Rudyard Kipling
fee for a contribution to our Christmas Number _Err.]
The Live Axle—Is It Dying?
The Editor, TEEE COMMERCIAL. MOTOR.
(du] Sir,—The recent letter from Messrs. David Brown and Sons, Ltd., • is goad evidence that the opinions of "The Inspector" are wide of the mark.
-" The Inspector " has evidently, like the writer, had a prolonged experience of motors, but unfortunately his technical conclusions appear to be at fault. •
He cites the early 10 h.p. chain-driven Wolseley as an example of the high efficiency of the chain drive, and then proceeds to • " wonder " Whether the efficiency of a good chaia drive makes "the chain drive preferable to the live axle." The ambiguity of "The Inspector's" article makes it misleading ; theefficiency of the early Wolseley has nothing whatever to do with the relative merits of the modern dead or live axle,, for the reason that the' early Wolseley engines were placed crossways to the chassis, whilst all modern engines are placed lengthways. Compare a modern dead arid live axle. In both cases we have a right-angle drive, but the dead axle has, in addition, two driving chains, which are bound to absorb a certain_ percentage of the power on its way to the road wheels. When these chains are exposed, as is generally the case, road grit soon works its way into the numerous rollers or joints, resulting in loss of efficiency and excessive wear and tear with the possibility of sudden breakage. These breakages not only cause delay on the road, but they are a source of clanger owing to the fact that the brake behind the gearbox is rendered inoperative. The use of the engine as an emergency brake is, in like manner, rendered impossible. The chain-driven light motoscar is practically extinct; the higher efficiency of the live-axle has won the day. What, then, hinders the universal adoption of the live axle on standard subsidy lorries ? There are three obstacles, inexperience, prejudice and road clearance.
• 1.—Inexperience. Those acquainted with the history of the M.T. in France since 1914 know that certain live axles were failures due to faulty design. When " The Inspector" refers to torque tubes causing great anxiety he is partially correct; certain makes, badly designed and badly constructed, have given repeated trouble. It is not, however, the principle which is wrong but the manufacturer.
2.—Prejudice. Certain motor critics, who are not actual designers, note the failure of certain live axles and condemn the system as applied to the three-ton lorry. This superficial criticism draws no distinguishing line between faulty design, faulty workmanship and faulty principle.
3.—Road clearance. This presents no difficulty under ordinary conditions. In Flanders, however, when one side of a lorry is low down in a sea of mud and the other side high up on a pave road, axle casings have been known to bump. But these lorries were designed for ordinary use. A well-known make of motorcar has again and again had the bottom of its eng.ine bumped on the pave roads of Flanders. The petrol engine is not, however, to be condemned on this account. The design merely requires modification.
Now, it is easier to raise an engine than a rear axle, because the position of the centre of the latter depends upon the size of the rear road wheels. Road clearance can be increased, however, by reducing the size of the axle casing, i.e., by the use of a smaller gear. A northern firm, making a speciality of worm gear, by a new process of manufacture, has been able to reduce the size of the gear without interfering with its load-carrying capacity. This, new improvement overcomes about the only remaining obstacle to the universal adoption of the live axle. It is noticeable that "The Inspector" talks about "torquetubes and their attachments" as a "necessary evil of the live axle" whilst he' omits all mention of the "necessary evil" of chain adjustment. Should one chain be more worn than the other, and both correctly adjusted, then the rear axle will be thrown out of line.
In my opinion the up-to-date manufacturer is now able, with the experience of the present war, to produce a live axle for heavy lorries which will outclass any chain-driven lorry ever made, and in course of time this latter typeof vehicle will, as in the case of the light motorcar, become practically extinct. '26, Russell Square, DRIVER DESIGNER. London, W.C. 1.
A Comment from " Agrimot."
The Editor, THE COMMERCIAL MOTOR.
[1563] Sir,—I must thank your three correspondents for their kind criticisms. "J.H." clearly explains the true motion of the spuds, and his conclusion is, in my opinion, quite a sound one. Sets of spuds are cheap,-and a variety could be stocked by tha farmer, who would be able to judge, after a little experience, which type was best suited to any one of the various grades of soil of which his holding consists. I think " Vectis's " criticism, even if it were founded on fact, could be described as a quibble. If the de pression and raising are simultaneous, which I cannot believe, the ultima' e, employment of the horse-power is still the same—depressing the soil. The horse power of a car engine is expended. in turning the axle shafts, and this takes place, to all intents and purposes, at the same time as the car wheels are being revolved. The main fact, that the ultimate employment of the horse-power is in driving the car, remains unaltered. That there is no actual lift and fall of the tractor wheels is plain to be seen.
Contrary to " Vectis's " belief, there is little or no power expended in driving the spuds into the ground. The main loss is, as I stated, in rolling, over them when they are in the ground. This is occasioned by the disturbance of the soil, already compressed by the weight of the machine, which must take place before, the spuds can move through the angle between the position at which they enter the soil and which they occupy when withdrawn. As regards the spuds, ease of attachment and detachment is essential for many reasons, but least of all for use on the roads.—Yours
faithfully, AGRIMOT. C53'
The Wood-Milne Cylinder.
The Editor, THE COMMERCIAL MOTOR.
[1564] Sir,—During the last two months the motoring public have been attracted by the claims put forward by the Wood-Milne Co. regarding a fabrie and rubber cylinder or "bolster." Without a full knowledge of the construction of the cylinder, it is difficult for any engineer to check whether the results claimed are within the bounds of possibility or not. From the information given in the various advertise
ments and descriptions which have appeared in the Press, it may be safely assumed that the " bolster " is constructed of cotton motor tyre canvas and rubber,' made in the same manner as a motor tyre.
Now for a few facts. The claim put forth that the " bolster " will withstand a working load of 1800 lb. per square inch, with a cylinder (internal) 12 ins. diameter. A simple calculation shows this to give a hoop tension of 10,800 lb. per square inch. Now, to withstand this load, a very elementary knowledge of textile strength will show that we should require about 60 layers of canvas of about 12 .oz-s. per square yard each. Allowing a fadtor of safety of 4, which would be considered small for this work, we have to use 240 layers of canvas, which, I submit, would be very much thicker than l ins, as stated.
I am fully convinced that the "bolster," as at present advertised, will not withstand a pressure of 600 lb. per square inch.—Yours faithfully, &rum..
The Tractor Question.
The Editor, THE COMMERCIAL MOTOR.
[1565] Sir,—Regarding " H.N.H.'s " letter in your issue of 22nd November, I can confirm his experience up to the hilt.On what principle—if any principle at all—the men to whom the handling of agricultural tractors is entrusted are appointed it is difficult to see. I know personally of men having little engineering training, or indeed none whatever, who have been appointed at good salaries to supervise the running and maintenance of the tractors, and who have repeatedly given proof of deplorable incompetence, causing great expense and the loss of valuable time.
Surely there should be some test applied before a man can call himself an engineer, and in this case he should be put through a searching examination as to his knowledge of the principles and practical working and repair of internal-combustion engines. If, this were done, there would be some fine weeding out of incompetents. Some ludicrous tales could be told about the type of man mentioned when up against a refractory engine. In some cases the farmer himself has had to step in and show the Man how to do it
But the sinful waste of time andmoney make it a very serious matter, and a heavy responsibility lies upon those who appoint these men.—Yours faithfully, RURAL. '
Wear on Chain-track Tractor Shoes.
The Editor, THE COMMERCIAL MOTOR.
[1566] Sir,—With reference to the remarks of your correspondent " Agrimot" (in your issue of the 22nd ult.) concerning the effect of wear on chain-track constructions, we have pleasure in directing your attention to the drive wheel and chain-tread construction of the Monarch rail-track tractors. In this design of -tractor this point has been fully met, as the driving wheel sprockets are doubled and so arranged that each pair of sprocket teeth_ meshes with two track shoes. As you will readily understand, all the pull of the drives comes on the rear track shoes, those forward of these.servin g. only to assist them. The pull, therefore, is not taken through the track pins, but directly by the track shoes, and wear on the pins, therefore, does not throw the shoes out of alignment. The makers tell us that these tracks will wear for years, although the pins are ordinary ones made from soft steel, and can be renewed when required very oheaply.--Yours faithfully,
Coventry, THE POWER FARM SUPPLY CO.