Technical Information - Airflex - #9

Product Alignment

Good shaft and component alignment is highly desirable to minimize un­necessary mechanical stresses in couplings, clutches, brakes, shafts, bearings and their supporting structure. Perfect alignment, which for all practical purposes is unattainable, can only occur if the dynamic axes of rotation are concentric throughout their entire lengths.

Misalignment is completely described by measurements of parallel and an­gular misalignment. Since both types of misalignment occur in the horizon­tal and vertical planes, top-to-bottom and side-to-side measurements must be taken.

Parallel misalignment, also referred to as offset or run out, occurs when the axes of rotation are parallel to each other. It is measured by attaching a dial indicator to one shaft; rotating the shaft with the indicator about the outside diameter of the other shaft and noting indicator readings.

Angular misalignment, also referred to as gap, occurs when the axes of ro­tation intersect each other Either a micrometer or dial indicator can be used to take gap measurements as shown in the figure.

Parallel and angular measurements are then used to determine the neces­sary adjustments. Initial shaft alignment should be done as accurately as possible. Foundation movement, frame deflection and expansion can change the initial alignment to the point where full misalignment capacity of the product is required. Although shaft speed generally dictates misalign­ment tolerances, the values shown in the table have been found acceptable for the Airflex product lines. The angular indicator reading should not ex­ceed the product of the table value and the diameter at which the indicator readings were taken.

Parallel

Angular

Note:

O Diameter at which measurements are taken.

Copyright Eaton Corporation, 1995, All rights reserved.

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