Shafting, Pulleys, Belting and Rope Transmission
The Power Handbooks Library
9781465637116
400 pages
Library of Alexandria
Overview
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. 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. 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. 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.
