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Mr. GREENE. I wish to say, in the beginning, that I would like to alter the wording of the topic. It would seem to border on presumption for me to say anything on the topic worded exactly as it is. I don't like to speak about the best design for transmitting power; I would prefer to call the topic a design, not the best. I have thought also it would please the members of the Association better for me to say what I have to say, and present a sketch of what I would illustrate, rather than read a paper. So I shall present this drawing,
, which is prepared for the actual case of a mill transmitting about one thousand horse-power, and present it as an illustration of transmitting the power into various rooms.
On this drawing the right-hand sketch represents a transverse section through a rope tower, showing the transmission of power from the main fly-wheel of the engine to the head lines of the main shafts in the various rooms. These head shafts are carried on steel beams which are built into the brickwork of the belt tower, and shown by longitudinal section. This longitudinal section gives the position of the shafts with relation to these beams. The shafts are carried by pillowblock bearings, and extend through thimbles in the wall into the main room. There is no great improvement in that over what is employed in any of our first-class mills.
The simple device I suggest is to place on the shaft, just outside the rope tower wall in the main room, a friction cut-off coupling. I do not propose to discuss the merits of the various kinds of friction cut-off couplings. I suppose all of you have any number of circulars setting forth the merits of these various couplings; but any good friction cut-off coupling can be placed in the main line of shafting, with a lever extending down within reach, possibly not of a man standing on the floor, but by going up a few steps it could be reached. Then, having that so arranged, it could be operated in stopping or starting the shafting in each room. This could be applied at any of the other lines of shafting.
I don't think it wise to enter into a discussion of the question of electric transmission, or having an individual motor placed on any line of shafting.
In this drawing the rope drive shown was arranged for a possible extension of the mill. The drive shown to the right is the one first used. The belt tower, in the event of an extension of the mill, is large enough, and space in the engine room is provided for another tandem compound engine.
If there are any questions which I can answer, I should be very glad to do so.
The PRESIDENT. You have heard the remarks of Mr. GREENE. You will now have an opportunity to ask him any questions, or discuss the subject in any way you choose.
Mr. BOURNE. I would like to ask what system of rope driving he finds to be the best.
Mr. GREENE. In any case where the power is considerable, anything above a hundred horse-power, I have found the English system, the individual ropes, altogether better.
The PRESIDENT. I have no doubt that some of the members present have had something to do with the rope-driving system, and we should be pleased to hear from them. Mr. RUSSELL. What is the life of
What is the life of a rope in comparison with the life of a belt, in a drive of that style?
Mr. GREENE. I don't know that anybody is able to answer that question definitely. Ropes have not been used in this country long enough, and there are no such conditions as would warrant an accurate answer. If I were to give an opinion, I should say that the life of a manila rope, under good conditions, would range from five to seven years. A good belt, if there is put on the amount of leather there ought to be, should have a life of at least twenty years.
The PRESIDENT. We have had them run thirty-nine years or more, and they are in good condition now. I would like to inquire of Mr. LEIGH if he is conversant with the rope drive.
Mr. LEIGH. In England many have gone into rope driving, and it is very popular; but personally I fail to see where the advantage is, except in the first cost. Every few years one or two ropes have to be replaced; whereas a belt, if properly applied, will last for thirty or forty years. I think there is more loss of power on the rope than on the belt system.
Mr. KNIGHT. What is the relative economy, as far as power is concerned, between the belt and rope systems ?
Mr. GREENE. As far as I know, there are no tests which will settle conclusively that question. I can conceive of a rope drive being run where the showing as regards power might be erroneous; but it makes all the difference in the world what the design of the groove is, and the relation of the rope to the groove. I did not intend to spring the question of rope driving on this body, and I want to be explicit on that point. I confined myself to the question I was asked to discuss, and I simply used that drawing in which ropes were used to illustrate my remarks. I am not here to apologise for the rope system. I might say that I have no reason to change the opinion I formed two or three years ago, – that, for a large amount of power,
, anything over five or six hundred horse-power, or where the power is concentrated and needs to be taken off to various head shafts in the mill, I know of no way the problem can be solved so satisfactorily as by the rope drive.
Mr. HERVEY KENT. In regard to rope driving, we have been taking some two hundred horse-power from one wheel with five ropes, between three or four years, and so far it has given us no trouble. We have had nothing to do since we put them on. It is necessary to be a little careful in starting up; we start that wheel a little before the others, so as not to throw the leading on the other side, and unless you have plenty of room you may have trouble in that direction.
Then again, I think it cost eighty-one dollars for the ropes, while the cost of a belt would be three or four times that. So, on the score of
, first cost, the ropes are much cheaper.
Mr. Johnston. How much less do the pulleys cost?
Mr. HERVEY KENT. Very much less; they are much lighter.
Mr. JOHNSTON. It depends on what rope you use.
Mr. HERVEY KENT. We use manila rope. Of course the grooves have something to do with it. I do not see why they may not go another year as well as they do now.
Mr. GREENE. With reference to the matter of trouble and care, in order that my position may not be misunderstood, I will mention one or two instances that came within my observation: Two years ago last June a mill requiring one thousand or twelve hundred horse-power was started with rope transmission, which I designed; there were twenty-seven one and three-quarter inch ropes. In May this year the ropes had been run twenty-three months. Three had never been touched; the others had been taken up once.
There was considerable slack in those three ropes, and it was expected that in two or three months they would have to be taken up. I have not heard of a belt that has been on that time that would not have to be taken up. But for the ropes to do good service they must have room; you cannot draw them tightly and keep taking them up without their giving out.
Unless the conditions are all right for good running, I would advise letting the rope drive alone and take the belt drive.
Mr. BIRKENHEAD. My experience of transmitting power by means of a round band or rope is, that it has never been looked upon in as favorable a light as it otherwise would have been, for this reason; you will find in very many cases where the attempt is made to transmit power from one part of a machine to another with a round belt, or band, the maker of the machine put a groove in his pulleys unsuited for frictional contact. Where positive drive is necessary, you will often
. find the groove that is to receive the band on an angle of ninety degrees, or square; now there is no more frictional contact in this case than there would be if the band lay on a flat surface,