Page images

ent the further the problems in belting are investigated; namely, that what we do not know about belting far exceeds our knowledge of the subject." Mr. CROMWELL in his Treatise on Belts and Pulleys (JOHN WILEY & Sons, 1888) says: "Notwithstanding the fact that many thousands of dollars are consumed every year by the rapid wear and destruction of our machine belts, and the immense field thereby opened for the practical study and application of the principles of economy in this connection there is no branch of machine-construction which is today in as crude and unsatisfactory a state as this all important transmission by belt and pulley."

As nearly all belts are made of leather we will confine our remarks to that class. You all know that the best leather belting is made from the hides of native steers of the North and West raised in the open and slaughtered at the age of four or five years. While the chemist and experimenter have discovered a number of methods of tanning which require a shorter time to accomplish, it is acknowledged generally that none produce such good belting leather as the old fashioned “ lay away" process of oak bark tanning. By this process it takes from nine to ten months from the time the hides are laid away till they are ready for the market. Before being tanned those portions of the hide unsuitable for belting (neck, belly and flank) are cut off leaving what is called the “belting butt," the usual dimensions of which are about six and a half feet long by four feet wide.

After the tanning process the “butts" are dried, in which state they are as hard as a board. They are then stuffed with greases and oils (different processes are used by different curriers) to render them flexible and fit for belting. In this process the cheaper grades of leather much of which is tanned by quick and less costly methods can be so “ loaded ” with glucose, sugar

of lead, heavy oils and greases as to give them the appearance of good leather. To this "loaded" leather is given what is called a "hard finish" which will deceive any but an expert. Thus the unscrupulous belt manufacturer can sell with good profit at a price absolutely prohibitive to a manufacturer who turns out only high grade belting. Both grades look alike and the inferior grade may weigh more per square foot than the other. The other day a belting manufacturer told us he had recently examined a piece of single belt made by another which weighed 26 ounces to the square foot, while his own belt of corresponding thickness weighed but 18 ounces to the square foot.

Under the new Victoria Pure Food Act every parcel of leather exported from Australia has to contain a certain certificate showing the amount of added weighting matter (sugar, glucose, epsom salts, etc.). The Boot and Shoe Manufacturers Association of this country, at their last annual convention passed a resolution designed to secure legislation to prevent or forbid the use of any foreign substance which is only used to add to the weight of sole leather. Whether it is wise or expedient for this Association to consider taking a similar action in reference to belting leather is a subject for consideration.

We are told that up to the present it has not been found possible to imitate the streak which shows the centre or back bone so that it is an easy matter to get belts made of centre stock when it is so specified. Four and a half feet is about the standard length for each sectional piece with laps. As a rule belting of the best stock will not wrinkle or "pipe” when bent back and forth repeatedly at a sharp angle. Sometimes wrinkles show at the ends of laps which are termed "fat" wrinkles. They represent the best possible grade for belting. If such laps do not exceed the standard length there is no cause for claiming that you have been cheated. A good belt should lie straight on the floor and be of uniform thickness.

Most manufacturers make several grades of belting which they usually advertise under special names. Before being made into belts the “butts" are sorted by men trained for the work just as wool and cotton are sorted before they are converted into yarn and cloth. From all this we can see that (as with oil) the buyer is really dependent on the integrity of the manufacturer. Would it not be the part of wisdom to select a concern in whom you have confidence and trust them to supply you with that which is best suited to your conditions? If they are honest they will treat you fairly as to price.

The Encyclopædia (New International) tells us that the annual production of belting and hose leather in the United States has grown in value from less than one hundred and sixtyone thousand dollars ($160,500) in 1850, to more than ten and a half million dollars ($10,623,177) worth in 1900. Surely a product of such value commands our attention and is worthy of the careful study of all who have to do with it.

In view of the many changes tending toward economy and better operation which are continually taking place in other mechanical lines, why has the subject of belts and belt transmission been given so little attention?

Is it because the belting bills are now so small there is no desire for further reduction?

Is it because it is not known that friction costs money and that to permanently reduce it is like discovering a mine from which will flow a steady stream of the much coveted "coin of realm” so long as the wheels of the mill turn? There

may be and doubtless are many reasons. Those which occur to us are:

Because experiments along such lines are left to the mechanical experts or professors of technical institutions who have the time and taste for such investigations.

2. As a rule those trained for superintendents and agents of cotton mills pass through all the departments of the mill except the engine room and the machine shop.

3. The transmission department (engine, belting, etc.) is in charge of one who has all he can do to keep the wheels turning, and who has no time nor inclination for anything that involves extra work.

4. Of the deep rooted trait in human nature to “let well enough alone,” and

5. The subject has not been brought to the attention of those vitally interested in the dividends of a plant with sufficient force to induce them to believe it " worth while."


So far as

our observation goes, except where the method about which we are to speak presently is followed, belts today are run as they were when their use began.

The money losses due to the ordinary management of belts may be classed under two headings:

1. Tight belts.

2. Belt slippage. On this subject Jones & Laughlins quote the following from a New England cotton mill engineer of high reputation : — “I believe that three-fourths of the trouble experienced in broken pulleys, hot boxes and etc., can be traced to the fault of tight belts. The enormous and useless pressure thus put upon pulleys must in time break them, if they are made in any reasonable proportions, besides wearing out the whole outfit, and causing heating and consequent destruction of the bearings. If manufacturers realized how much this fault of tight belts cost them, in running their mills, probably they would' wake up.'”


Below are some figures showing the power it takes in average modern mills, with first class shafting, to drive the shaiting alone (friction load.):

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][subsumed][merged small][merged small][ocr errors][ocr errors][ocr errors][subsumed][merged small][merged small][merged small][merged small][ocr errors][ocr errors][ocr errors]

These may be taken as a fair showing of the power that is required in many of our best (not worst) mills to drive shafting. It will be seen that the percentage is large- from 22 per cent. upwards. It is unreasonable to think that all that power is consumed by a legitimate amount of friction of bearings and belts. It is out of all reason, and I know of no cause for such loss of power but tight belts. These, when there are hundreds or thousands in a mill, easily multiply the friction in the bearings and would account for the figures.

Taking the cost of a horse power at 35 pounds coal per day, per horse power, and allowing 15 per cent. of the whole load as a reasonable loss from friction one can see that the cost of running tight belts is no inconsiderable one, to say nothing about the loss resulting from the shortened life of the entire equipment."

We are told that a mill with 1,000 looms running on print cloth will turn out about 5,000 pieces per week. If there is an average belt slippage throughout the plant of 2 per cent. (Do you take the speed of your various lines of shafting at full load and again at no load to ascertain what the slippage is?) there will be a loss of 100 pieces per week. Figuring the value of each piece at $2, it will amount to $200 per week or $10,000 per year. It will pay to go to a good deal of trouble to prevent such a loss. When is a belt tight in the sense of being “too tight” and

a when is a belt not“ tight enough?” The tightness of a belt is not ordinarily criticised until it causes a hot bearing. On the other hand a belt is considered "tight enough" until slippage becomes apparent to the senses, or until as we have been told it is customary in some mills, the regular time comes round to shorten (tighten) every belt in the plant.

From our point of view any belt is “too tight” that is wasting power in friction that can be easily saved, while any belt is “ tight enough” that runs all right, does not slip, and has sufficient pulley contact to keep well within the strength of the leather to withstand the strain put upon it.

We believe in regularly feeding a belt with that which will make and keep it healthy, just as you believe in regularly oiling a bearing. You, of course, know that every fibre of a belt in motion is constantly changing its position in relation to its

« PreviousContinue »