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At Buchanan, in the State of Michigan, at the flour mill of Bainton Bros., three years ago, a second dam was built 1,100 feet down stream from the main dam, and the power of a second water wheel was carried back to the mill with an American system rope transmission put in by Dodge Manufacturing Company, thus enabling the power of the water to be used again after it had passed. When more power shall be required, another dam and another transmission will provide it. But an interesting incident of this transmission must not be overlooked. Two years ago a freshet carried away the main dam, and, while it was being rebuilt, the second, with its transmission, continued to run the mill.
When the transmission covers a long distance, economy and convenience require that the power shall be carried over by the fewest possible passes of the rope, and it was, at first, usual to employ a single rope, having a diameter sufficient to carry the power, using winders at each end to obtain the required adhesion to the driving and driven wheels.
It is manifest that the splice must be the weakest point of the rope and that it will be most likely to fail at that point while it is passing the laboring side of its circuit. It will be equally evident that a failure of the rope, while under greatest strain, will be most likely to lead to disasters.
To reduce this liability to the lowest point, we therefore resort to what we term a double wind. That is, the rope passes twice between driver and driven, and the laboring strain is divided. Several important points are gained. The cost is not increased materially because a smaller rope may be employed. Only one-half the laboring strain is imposed upon the splice, and smaller wheels may be employed.
The value and importance of the American System of Rope Transmission is shown by the fact that this system originated with the Dodge Manufacturing Company only five years ago, and has only been before the public about four years, during which time not less than twelve to fourteen hundred transmissions have been sold by this company, and a number of imita
tors have been attracted to this new field. Imitation is the sincerest testimonial to novelty and utility.
The advantages to be derived from rope drive are numerous, and to summarize :
(1) Small first cost, which also applies to renewals.
(2) Losses of time by stoppages reduced to a minimum (3) Small space required for large powers.
(4) No slip.
(5) Light running, less noise and a more positive drive. (6) Adapted to carry any power any distance and at any angle.
(7) A saving of fully fifteen per cent. of power under the most favorable circumstances for a belt, and in some cases would equal fully sixty per cent. saving in power, as in long distances.
I have written thus fully in reference to the American System of Rope Transmission, not because it is my wish to foster or bring to the front any particular patent, but as there appears to be an especial interest manifested in rope driving, and, as far as lay in my power, to oblige your worthy association.
Mr. President, I should like to ask Mr. DODGE two questions; the first in regard to what he has found to be the preferable form or angle for the groove in the pulleys transmitting the power by rope, and, secondly, what he considers the safe and desirable strain to be applied to ropes in transmission. That is, what portion of the breaking strength of the rope is it safe to apply?
Mr. DODGE. We have adopted, in our practice, the United States Standard V thread angle (of about sixty degrees) for the grooves in our wheels; one that allows the rope to bind firmly on two sides, and, at the same time, will lift easily out of the groove, without any stick or hang, after having done its work. In answer to the second part of the question, we assume that it is safe to use, in indoor practice, from two to three per cent. of the breaking strain of the rope; and in outdoor practice, as in long-distance transmissions, a greater per cent. may be used; say from three to five per cent. of the breaking strain of the rope.
Mr. DODGE then explained a device in use in his company's works, whereby notice was given to the engineer, by an electric alarm, in case a breakage of the fibres of the rope should take place, causing the least strand of the fibre to stick out so as to strike the device and instantly alarm the engineer, and also automatically throw the clutch out of friction and stop the transmission, thus preventing damage.
Recently we had a boy, wiping the machinery, who let a small piece of waste get fast on the rope, and, as the rope came around, it struck the tell-tale (as we call it) and automatically threw out the friction clutch and turned in the alarm. It was supposed that the rope had given out in some part, but upon examination the little piece of waste was found clinging to the tell-tale. It was not more than two or two and a half inches long, very light, perhaps four or five threads. This little piece of waste set the alarm bell to ringing, and it would not stop until attended to. I cite this little incident to show how perfectly under control a rope drive may be held, and when a
break occurs in the rope, it is but a few minutes' work to resplice it; and I think the liability of a rope breaking is less than that of a belt.
Mr. GARSED. If you have a continuous rope passing twentyfour times around a drum, that would be one twenty-fourth of a belt transmitting the same power. Now, if that rope breaks, the whole power of the machinery is relieved, and the engine continues on under that pressure. Now, I claim that a twentyfour-inch belt would not be so apt to break without showing it as one twenty-fourth part of the rope. Which would be most likely to give out, a belt twenty-four inches wide, or a rope of one inch?
Mr. DODGE. We are using, in our main transmission, a rope of about that size, and we are using only one or two per cent. of the strength of the rope. When a belt is used for a like transmission, the same will hold good (one or two per cent. only being used); but the belt is required to have a large surface in contact with the wheels to transmit the power, and must usually have a large, heavy tightener, which makes the belt more liable to breakage. The labor of the rope being very light and of even tension, it is not liable to break, or, at least, not any more so than is a belt.
A MEMBER. Mr. Chairman, it would be interesting if Mr. DODGE would tell us something about the difficulties to be overcome in running his rope out of doors; how much the atmospheric and climatic effect is upon a rope, - snow and rain.
Mr. DODGE. The atmosphere does not affect the rope to any great extent, as a rope will run just as well out of doors as in doors. My theory is that when a rope is constantly bending around a wheel, either in or out of doors, air is being constantly worked through it, and serves to preserve it. If a new rope should be hung up in an old apple tree, it would deteriorate very rapidly, and would be worthless in a short time; but, on the contrary, we have ropes running that have been doing so constantly for two or three years, out of doors, and are apparently in good condition. However, a rope running out of