Shafting, Pulleys, Belting and Rope Transmission

by Hubert E. Collins

Fig. 32.

It is evident that neither method 1 nor 2 can here be applied to solve the alinement problem. If the driving pulley B and the driven pulley A are both in place, the following method can be used to advantage.

Fasten, or let somebody hold, one end of a line against pulley B's rim at B¹; carry the line over to A at A²; now sweep the loose A² end of the line toward pulley A until the line just touches pulley B's rim at B². When the line so touches—and it must just barely touch or the measurement is worthless—A¹ and A² of pulley A must be just touched by or (if B and A are not of a like face width, as in Fig. 32) equidistant from the line.

A single, two-hanger-supported length of shafting thus lined is bound to be in parallel; but where the so adjusted shaft line consists of two or more coupling-joined lengths supported by more than two hangers, only pulley A's supporting portion of the shaft between its immediate supporting hangers 1 and 2 is sure to be lined; the rest may be more or less out.

To make a perfect job, fix a string in parallel with shaft length 1 and 2, stretching along the entire length of the adjusted shaft, and aline the rest of the shaft length to it.

When there are no pulleys in place to go by, or when, as occasionally happens, the wabbly motion of pulley B (when running) indicates that, having been inaccurately bored or bushed, or being located on a sprung shaft length, its rim line is not at right angles to the shaft line, the method shown in Fig. 33 can be resorted to.

Instead of the nail used in methods 1 and 2, use a board about 8 to 12 inches long and of a width equal to considerably more than half of shaft B's diameter. By nailing this board x to the measuring rod c at any suitable angle, you will be enabled to reach from the end a well into the shaft B, as at b, and from b′ well into A, as a′. By keeping the board x along its entire length in full contact with the shaft B at both 1 and 2, the angular position of rod C is bound to be the same in both instances, and you will thus (by the use of a square, as in Fig. 31) be enabled to aline A parallel with B.

Fig. 33.

In all instances of parallel adjustment here cited it is assumed that both the alined and the alined-to shafts have been, as to secure accuracy of result they must be, properly leveled before starting to aline.