Opinions from Others.
Page 20
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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 type-written by preference. The right of abbreviation is reserved, and no responsibility for the views expressed is accepted. In the case of experiences, names of towns or localities may be withheld.
Why the Heavy Road Locomotive ?
The Editor, THE COMMERCIAL MOTOR.
[1,397] Sir,—In a letter signed " Change " in your 20th July issue, claim is made that an internal-combustion tractor can haul three or four times its own weight. While any tractor may do so on good level road, I question if it is possible in general work. I recently saw a 14-ton compound engine drawing about 26 tons total up a steep rough hill. Presently the driving wheels, the plates on which were good, slipped, and, moreover, the front wheels lifted at times. At such moments, the whole weight of the engine is on the driving wheels, yet the load had to be divided, and taken up in instalments. How could a lighter oil tractor dobetter ? Would it not slip earlier, under similar conditions of road and load ? The failure was due to lack of adhesion, not from want of power. I do not see that any other point of attachment for the drawbar could have helped much. ---Yours faithfully, "ENQUIRER."
rhe Hardening of Steel.
The Editor, THE COMMERCIAL MOTOR.
[1,398] Sir,—Having read the articles on steel that have lately appeared in your journal, I think it might be of considerable interest to others if the following very practical device were known.
As pointed out by the author of these recent articles, steel to be hardened requires quenching at the point of recalescence. Now at that point there is no magnetism. Hence a horseshoe magnet with elongated pole pieces can be used to pick the portion to be hardened out of the fire. The magnet may be held over a bath of oil or water, so that when the steel piece at the ends of the magnet cools and recalescence occurs the latter will drop off and be quenched. What more simple and effective application of these known principles is possible ? I believe that Mr. Mudford of Holloway and Mr. Taylor (of Taylor, Taylor and Hobson) of Leicester were jointly the first authors of this device, and I also believe they sell a simple apparatus for carrying out the operation for small work. I, at any rate, can vouch for the excellency of small tools hardened in this manner.—Yours faithfully,
F. HERON ROGERS, Broad Sanctuary Chambers,
Westminster, S.W.
Petrol Storage Plants.
The Editor, THE COMMERCIAL MOTOR.
[1,399] Sir,—In reply to your correspondent " Trincomalee," we beg to state that "London Works'" letter was sent to our New York office for consideration ; their reply has not yet been received. In order to set your correspondents' minds at rest we will state briefly a few facts about the hydraulic system for the storing and handling of petrol.
The cost of the system is immaterial, as the saving due to the lack of evaporation, the minimum of time and labour required to draw petrol, and the freedom from carburetter troubles caused by dirt in the petrol, more than pay for the system inside of a year's time. In a number of installations the reduction in insurance premiums for the first year has more than equalled the cost of installing the system.
Petrol and water will not mix, and the surest way to prove this is to fill a bottle, half with water and half with petrol, then shake the bottle, and watch the re sult; the petrol will immediately rise to the top of the bottle, leaving the water, which, of course, is heavier, at the bottom. The reason, doubtless, why "London Works" raised this point is because of the fact that in all other systems the petrol is pumped from the bottom of the tank, where, of course, all the water and dirt settle ; whereas, in the hydraulic system, the petrol is drawn from the top of the tank ; under no circumstances whatever can water, dirt, or other foreign matter mix with the spirit.
As petrol and water will not mix, and as, in the hydraulic system of storage, the petrol never goes be
low the bottom of the tank, it is absolutely impossible for any petrol to be discharged into the drain. This can very easily be proved. by bearing in mind the fact that the underlying principle of the system is a " U " tube with unequal legs, the water being in the shorter leg and the petrol in the longer one. S,uppose that a glass " U " tube be taken with one leg 8 in. long and the other leg 10 in. long : pour water into the shorter leg until it overflows ; the water will now stand m the longer leg at the same level as the top of the shorter leg ; now pour petrol into the longer leg, and water will immediately overflow from the shorter leg. If we continue to pour in petrol until it overflows the top of the longer leg, we are forced to the conclusion that that is all the petrol that can be got into the tube. It will then be found that the separation between the two fluids will be about 41 in. below the top of the shorter leg, the water and the petrol heads being in the ratio of 12 to 17. On a real system, this separating line represents the level of the bottom of the tank. As the petrol cannot be forced below this level, and as the water flowing from the tank carries no petrol mixed with it, it is evident that no petrol can be carried into the drain.
The head of water necessary for the delivery of the petrol is obtained from the water float box, which is situated about 3 ft. above the floor level. The water supply of the building need only be sufficient to raise the water to the float box and any public water supply will do this. The certain head of water is used to raise the petrol to the required height to be fed into vehicle tanks, while the speed of delivery of the petrol can be controlled by adjusting the quantity of water entering the tank ; for instance, if 10 gallons of water per minute are allowed to enter the tank, 10 gallons of petrol will be delivered in the same time ; while if 30 gallons of water per minute are allowed to enter, naturally 30 gallons of petrol will be forced out. To prevent the water from freezing there is a drainage attachment which keeps all the water below ground. In Detroit, the home office of the company, ' we have this system installed all over the city, and as the temperature there during the winter drops down to 20 or 30 degrees below zero without inconveniencing the system, we see no reason why the milder winters of London should affect its operation. If your correspondents would care to go further into the matter, the writer would be pleased to meet them by appointment and show them the many advantages of the hydraulic system over any other way of storing and handling petrol.—Yours faithfully,
HYDRAULIC OIL STORAGE COMPANY, HARVEY E. NEWELL, Sales Manager.