Part 1

SHAFTING, PULLEYS, BELTING AND ROPE TRANSMISSION

THE POWER HANDBOOKS

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BY PROF. AUGUSTUS H. GILL

OF THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY

ENGINE ROOM CHEMISTRY

BY HUBERT E. COLLINS

BOILERS KNOCKS AND KINKS SHAFT GOVERNORS PUMPS ERECTING WORK PIPES AND PIPING SHAFTING, PULLEYS AND BELTING

BY F. E. MATTHEWS

REFRIGERATION. (In Preparation.)

HILL PUBLISHING COMPANY

505 PEARL STREET, NEW YORK

6 BOUVERIE STREET, LONDON, E. C.

THE POWER HANDBOOKS

Shafting, Pulleys, Belting

AND

Rope Transmission

COMPILED AND WRITTEN

BY

HUBERT E. COLLINS

Published by the McGraw-Hill Book Company New York

Successors to the Book Departments of the

McGraw Publishing Company Hill Publishing Company

Publishers of Books for

Electrical World The Engineering and Mining Journal The Engineering Record Power and The Engineer Electric Railway Journal American Machinist

_Copyright, 1908_, BY THE HILL PUBLISHING COMPANY

_All rights reserved_

_Hill Publishing Company, New York, U.S.A._

INTRODUCTION

THIS handbook is intended to furnish the reader with practical help for the every-day handling of shafting, pulleys and belting. These are allied in the operation of plants and it is a pretty generally conceded fact that all three are much neglected by many operators.

A close perusal of these pages will enable the reader to determine the best course to pursue in the most common instances and in various troubles, and in all articles there are suggestions for similar cases which may arise.

For instance, the need of belt dressing as a preservative, now generally conceded by most authorities, is fully covered in Chapter XI and the result of a test made by disinterested parties to find the degree of efficiency of four of the best known dressings is given. The results are of importance to all belt users.

A portion of the book is also given to rope transmission which is in more general use to-day than ever before, and in this connection some advice is offered by experts as to the selection and care of the rope. Rope splices and how to make them will also prove valuable to many engineers.

The author wishes to make acknowledgment to various contributors to _Power_ whose articles are used herein, and to some special contributors, from whose articles small portions have been taken. Acknowledgment is also made to Stanley H. Moore, the author of "Mechanical Engineering and Machine Shop Practice" for the section on splicing.

HUBERT E. COLLINS.

NEW YORK, _November_, 1908.

CONTENTS

CHAP. PAGE

I SHAFTING HINTS 1

II SHAFTING HINTS 21

III SHAFTING HINTS 32

IV TRUING UP LINE SHAFTING 49

V APPARATUS FOR LEVELING AND LINING SHAFTING 54

VI SOME PRACTICAL KINKS 61

VII PRACTICAL METHODS OF LOOSENING PULLEYS 65

VIII SPLICING LEATHER BELTS 72

IX CARE AND MANAGEMENT OF LEATHER BELTS 89

X BELTING--ITS USE AND ABUSE 99

XI A COMPARATIVE TEST OF FOUR BELT DRESSINGS 102

XII BELT CREEP 106

XIII ROPE DRIVES 108

XIV A NEW SCHEME IN ROPE TRANSMISSION 115

XV HOW TO ORDER TRANSMISSION ROPE 122

XVI A BELTING AND PULLEY CHART 129

XVII SPLICING ROPE 135

XVIII WIRE ROPE TRANSMISSION 143

I

SHAFTING HINTS[1]

IN the installation, maintenance and repair of shafting, as in all other things, there is a right and a wrong way; and though the wrong way ranges in its defects from matters causing trivial inconvenience to absolute danger, the right too often--owing to lack of knowledge or discernment--finds but scant appreciation.

[1] Contributed to Power by Chas. Herrman.

Where, as is often the case, the end of a shaft is journaled to admit of the use of an odd, small-bore pillow block or wall-box hanger, the journaled part should equal in length twice the length of the hanger bearing plus the length of the collar. The hanger can thus readily be slid out of the wall box, and the necessity of uncoupling this shaft length and removing it before access to the bearing for purposes of cleaning or repair is done away with.

A plank or board _A_ (Fig. 1), about 1/4 to 1/2 inch longer than the distance from the bottom of the shaft to the floor, can be used to good advantage at such times to free the hanger of the shaft's weight, and to prevent the shaft's springing from its own weight and the pulleys it may be carrying.

Should it become necessary to place a pulley with half the hub on and half off the journaled part, this can readily be done by the use of a split bushing, as shown in sectional view of Fig. 1.

Very often a small-sized bearing is used and the shaft journaled off to act as a collar. Of this procedure it can only be said that if done with the idea of making a "good job" it signally fails of its object; if of necessity (a collar being insufficient), then the shaft is heavily overloaded and serious trouble will result, because of it.

It is advisable to center punch, or otherwise mark, the ends of both shafts held by a compression coupling close up against the coupling, and both edges of the coupling hub should have a punch mark just opposite and close to the shaft punch marks. These marks will serve at all times to show at a moment's glance any end or circumferential slippage of the shafts within the coupling. The same method can be resorted to for proof of pulley slippage.

When a new line of shafting is put up, the foot position of each hanger should be clearly marked out on their respective timbers _after_ the shaft has been brought into alinement. Hangers can thus be easily put back into their proper place should timber shrinkage or heavy strains cause them to shift out of line. This idea can be applied to good advantage on old lines also, but before marking out the hanger positions the shaft should be tried and brought into perfect alinement.

Hangers that do not allow of any vertical adjustment should not be used in old buildings that are liable to settle. Shafting so run pretty nearly always gets out and keeps out of level.

In flanged bolt couplings (Fig. 1) no part of the bolt should project beyond the flanges. And where a belt runs in close proximity to such a coupling, split wood collars should be used to cover in the exposed coupling flanges, bolt heads and nuts. Countershafts have been torn out of place times innumerable by belts getting caught and winding up on the main line.

Whenever possible a space of 8 to 10 inches should be left between the end of a shaft line and the wall. A solid pulley or a new coupling can thus readily be put on by simply uncoupling and pushing the two shaft lengths apart without taking either down. Ten inches does not represent the full scope of pulleys admissible, for so long as the pulley hub does not exceed a 10-inch length the pulley face (the more readily in proportion to the larger pulley diameter) can be edged in between the shafts.

Fig. 2 is an instance of bad judgment in locating the bearings. In one case this bearing overheated; the remedy is either to re-babbitt the old box or replace it with a new one.

Both pulleys were solid and the keys--headless ones--had been driven home to stay. The rims of both pulleys almost touched the wall, and the circumferential position on the shaft of both these pulleys was such as to preclude the possibility (owing to an arm of _a_ being in a direct line with key _B_^1 and arm of _b_ with key _a_^1) of using anything but a side offset key starting drift.

An effort was made to loosen _b_ (which was farthest from the wall) by sledge-driving it toward the wall, hoping that the pulley might move off the key. The key, as was afterward found out, not having been oiled when originally driven home had rusted in place badly; though the pulley was moved by sledging, the key, secure in the pulley hub, remained there.

Ultimately one of us had to get into pulley _b_, and, removing cap _c_, hold the improvised side offset, long, starting drift _D_ in place against _B_^1 at _b_^2 while the other swung the hand sledge at _a_. The entering end of the key, not having been file chamfered off, as it should have been (see _E_), our starting drift burred it up; so, after having started it, we had the pleasure of getting into _b_ to file the key end _b_^2 into shape so as to admit of getting it out.

The solid pulley _b_ has since been replaced with a split pulley.

By the arrangement, as shown in Fig. 3, of the rim-friction clutch on the driven main shaft _B_ and the driving pulley on the engine-connected driving main shaft _A_, no matter whether _B_ shaft is in use or not--_i.e._, whether the clutch be in or out of engagement--so long as _A_ shaft is in motion the belt _C_ is working.

Main line belts come high, and the more they are used the sooner will they wear out. By changing the clutch from shaft _B_ to _A_ and the pulley _D_ from _A_ to _B_, belt _C_ will be at rest whenever _B_ is not in use. Where, however, these shafts are each in a separate room or on a different floor (the belt running through the wall or floor and ceiling, as the case may be) the clutch, despite belt wear, should be placed directly on the driven shaft (as _B_), so as to provide a ready means for shutting off the power in cases of emergency.

Figs. 4, 5 and 6 represent a dangerous mode, much in vogue, of driving an overhead floor. An extremely slack belt connects the driving shaft _A_ and the driven shaft _B_; when it is desired to impart motion to the driven shaft the belt tightener _C_ is let down and belt contact is thus secured.

This tightener system is called dangerous advisedly, for few are the shops employing it but that some employee has good cause to remember it. Unlike a clutch--where control of the power is positive, instantaneous and simple--the tightener cannot be handled, as in emergency cases it has to be.

In any but straight up and down drives with the driven pulley equal to or larger (diametrically) than the driver, unless the belt have special leading idlers there is more or less of a constant belt contact with its resultant liability to start the driven shaft up unexpectedly. When the tightener is completely off, the belt, owing to heat, weight or belt fault, may at any time continue to cling and transmit power for a short space, despite this fact.

These tighteners are usually pretty heavy--in fact, much heavier than the unfamiliar imagines when on the spur of emergency he grapples them, and trouble results.

Tightener (in Fig. 5) _A_ is held in place by two threaded rods _B_--as shown by slot _a_ in _A_^1--and regulated and tightened by ring-nuts _C_ working along the threaded portion of _B_. _C_ (of Fig. 4) is also a poor arrangement. Fig. 6 is the best of them all.

Apropos of clutches, great care must be exercised in tightening them up while the shafting is in motion, for if the least bit overdone the clutch may start up or, on being locked for trial (according to the clutches' structure), continue running without possibility of release until the main source of power be cut off. Nothing can exceed the danger of a clutch on a sprung shaft.

Heavily loaded shafting runs to much better advantage when center driven than when end driven, and what often constitutes an overload for an end drive is but a full load for a center drive. To illustrate, here is one case of many: The main shaft--end driven--was so overloaded that it could be alined and leveled one week and be found out one way or the other, frequently both ways, the next week. Being tired of the ceaseless tinkering that the condition under which that shaft was working necessitated, the proprietors were given the ultimatum: A heavier line of shafting which would be sure to work, or a try of the center drive which, owing to the extreme severity of this case, might or might not work.

A center drive, being the cheapest, was decided upon. Pulley _A_, Fig. 7, which happened to be a solid, set-screw and key-held pulley, was removed from the end of the shaft. The split, tight-clamping-fit pulley _B_, Fig. 8, was put in the middle of the shaft length; the gas engine was shifted to accommodate the new drive, and hanger _C_^1 was put up as a reinforcement to hanger _C_ and as a preventive of shaft springing. After these changes the shaft gave no trouble, so that, as had been hoped, the torsional strain that had formerly all been at point 1 must evidently have been divided up between points 2 and 3.

When a main shaft is belted to the engine and to a countershaft, as shown in Fig. 9, the pulley _A_^1 gets all the load of main and countershafts. In the arrangement shown in Fig. 10 point 1 gets _A's_ load and 2 gets _B's_ load and is the better arrangement.

Where a machine is situated close to one of the columns or timber uprights of the building it is very customary to carry the belt shifter device upon the column, as in Fig. 11. The sudden stoppage of a machine seldom does any damage, whereas an unexpected starting may cause irreparable damage and often even endanger the limb and life of the machine operative.

To avoid the possibility of some passing person brushing up against the shifting lever and thus starting the machine, the tight and loose pulleys of the countershaft should be so placed that when _A_ is exposed--that is, away from the column--its accidental shifting shall stop the machine. Fig 12 makes this point clear.

This arrangement is often used to save a collar (at _A_). The oil runs out between the loose pulley and the bearing, especially if the latter be a split bearing; the loose pulley, instead of being totally free when the belt is on the tight pulley, acts more or less, in proportion to the end play of the shaft, as a buffer between the tight pulley and the bearing; finally, the tight pulley is deprived of the support (which, when under load, it can use to good advantage) a nearer proximity to the hanger would give it.

The shafts of light-working counters should not be needlessly marred with spotting or flats for collar set-screws, nor should cup or pointed set-screws (which mar a shaft) be used. If the collar be sharply tapped with a hammer, diametrically opposite the set-screw, while it is being tightened up, all slack is taken out of the collar; and the hold is such that, without resource to the same expedient when loosening the collar, a screwdriver will scarcely avail against a slotted set-screw.

When required to sink the head of a bolt into a timber to admit of the timbers lying snug in or against some spot, if allowable, the bolt's future turning can be guarded against by cutting the hole square to fit the bolt head. But where a washer must be used, the only positive and practical way to prevent the bolt from turning is to drive a nail (as shown) into _A_ (Fig. 13) far enough for the nail head to flush _B_; now bend the head down behind the bolt toward _c_. It is evident that if the bolt tries to turn in the direction of 3 the nail end (wood held) will prevent it; if toward 4, the nail head will be forced against the wood and catch hold of the bolt head.

Large belts of engines, dynamos, motors, etc., when in need of taking-up are usually attended to when the plant is shut down; that is, nights, Sundays or legal holidays. At such times power is not to be had; and if the spliced part of the belt, which must be opened, shortened, scraped, re-cemented and hammered, happens to be resting against the face of one of the pulleys, is up between some beams or down in a pit, the chances of the job, if done at all, being any good are very slim.

The spliced part of a large belt should be clearly marked in some permanent and easily recognizable way (a rivet, or where the belt is rivet-held at all its joints some odd arrangement of rivets is as good a way as any). This marking will minimize the possibility of mistake and enable the engineer to place the belt splice in the position most favorable for the belt-maker's taking-up.

In wire-lacing a belt, very often, despite all efforts and care, the edges of the belt (_A_, _B_) get out of line, as shown in Fig. 14, and make the best of jobs look poor. By securing the belt in proper position by two small pieces of wire passed through and fastened at 1, 2, 3 and 4, Fig. 15, the lacing can be more conveniently accomplished and the edge projection is avoided. When the lacing has progressed far enough to necessitate the removal of wires _c_ _d_, the lacing already in place will keep the belt in its original position.

A wire lacing under certain conditions will run a certain length of time to a day. On expensive machinery whose time really is money it pays to renew the lacing at regular intervals so as to avoid the loss of time occasioned by a sudden giving out of the lace.

Never throw a belt on to a rim-friction or other kind of clutch while the shaft is in full motion. Belts, when being thrown on, have a knack, peculiarly their own, of jumping off on the other side of the pulley. And should a belt jump over and off on the wrong side and get caught in the clutch mechanism, as the saying goes, "there will be something doing" and the show usually comes high. It pays to slow down.

A mule belt (transmitting in the neighborhood of or considerably over 25 horse-power) that runs amuck through the breaking down of the mule can make enough trouble in a short time to keep the most able repairing for a long while.

No matter what the pulley shafts holding arrangement and adjusting contrivance may be, all of the strain due to belt weight, tension, and the power transmitted falls mainly at points _A_, _A_^1, Fig. 16; and it is here that, sooner or later, a pin, set-screw or bolt gives way and the belt either gets badly torn up, rips something out of place, or a fold of it sweeping to the floor slams things around generally until the power is shut off.

The remedy is obvious: Reinforce _A_, _A'_ by securing _B_, _B'_ to the supporting shaft _c_ at _c_^1, _c_^2. The yoke _x_ is a reliable and practical means to this end. Straps _a_ held by the nuts _b_ hold the yoke securely on the supporting shaft _c_, while the pulley-shaft ends _B_, _B'_ are held in the _U_ of the yoke at _w'_ at any desired distance from _c_ by means of the adjustment provided by the nuts _b_.

The end of a hanger bearing was badly worn (Fig. 17). The cap could be lifted out by removing bridge _A_, but the shaft interfered with the lifting of the bottom out, owing to its being held in the hanger slides. It had to be removed and we were called upon to put it into shape by re-babbitting.

Being a newspaper plant, money was no object; the time limit, however, was three hours, or hands off. Opening the 30-inch engine belt and removing the interfering shaft length was out of the question in so short a time. So the job was done as follows: The shaft was braced against down sag and engine pull along the line _B_ _C_ by a piece of timber at _A_, and against pull on _B_ _D_ by timber arrangement _X_; timber _y_'s points _y_^1 and _y_^2 resting against the uprights at 1 and 2, timber _z_ wedged in between _y_ at _y_^3 and the shaft at 4, thus acting as the stay along line _B_ _D_. The nuts and washers _a_, _a_ were removed; the bolts driven back out of the bracket; the end of a rope was thrown over the shaft at _b_, passed through the pulley and tied to the bracket and hanger which, as one piece, were then slid endways off the shaft and lowered to the floor. The bearing was cleaned, re-babbitted and scraped, everything put back, stays removed and the shaft running on time with a half-hour to the good.

When desirable to keep a shaft from turning while chipping and filing flats, spotting in set screws or moving pulleys on it, it can be done by inserting a _narrow_ strip of cardboard, soft wood or several thicknesses of paper between the bearing cap and the top of the shaft and then tightening the cap down.

The packing, 1-16 to 3-16 inch thick and about as long as the bearing, must be narrow; otherwise, as may be deduced from Fig. 18 (which shows the right way), by the use of a wide strip in the cap the shaft is turned into a wedge, endangering the safety of the cap when forced down. At point 3 packing does no harm, but at 1 and 2 there is just enough space to allow the shaft diameter to fit exactly, with no room to spare, into the cap bore diameter.

As a very little clamping will do a good deal of holding the clamping need not be overdone. A shaft can also be held from turning, or turned as may be desired, by holding it with a screw (monkey) wrench at any flat or keyway, as shown in sectional view, Fig. 19.

When a shaft breaks it is either owing to torsional strain caused by overload, springing through lack of hanger support at the proper interval of shaft length, the strain of imperfect alinement or level, or a flaw.

An immediate temporary repair may be effected by taking some split pulley that can best be spared from another part of the shaft and clamping it over the broken part of the shaft, thus converting it, as it were, into a compression coupling. The longer the pulley hub the better the hold; spotting the set-screws--that is, chipping out about 1/8-inch holes for their accommodation into the shaft--is also a great help.

If when the shaft breaks it has not been sprung by the sudden dropping of itself and the pulleys that were on it, a permanent repair can be effected, after correcting the cause of the break, by the use of a regular key-less compression coupling.

If it has been sprung, a new length comes cheapest in the wind-up; and if overload was the original cause of the trouble, only a heavier shaft or a considerable lightening of the load will prevent a repetition.

In Fig. 20 _A_ shows how to drive to make belt weight count in securing extra contact. In _B_ this weight causes a loss of contact. Bearing in mind that _B_ is not only a loss from the normal contact but also a loss of the extra contact that _A_ gives, it will readily be seen how important a power-saving factor the right sort of a drive is--especially on high-speed small-pulley machines, such as dynamos, motors, fans, blowers, etc.