Machinery's Handbook, 31st Edition
Involute Splines
2337
Table 3. Basic Dimensions for Involute Splines ANSI B92.1-1996
Min Effective Space Width (BASIC), S v min 30 deg φ 37.5 deg φ 45 deg φ
Min Effective Space Width (BASIC), S v min 30 deg φ 37.5 deg φ 45 deg φ
Circular Pitch, p
Circular Pitch, p
Pitch, P / P s
Pitch, P / P s 2.5 ∕ 5
1.2566 0.6283 0.6683 1.0472 0.5236 0.5569 0.7854 0.3927 0.4177 0.6283 0.3142 0.3342 0.5236 0.2618 0.2785 0.3927 0.1963 0.2088
… 20 ∕ 40 … 24 ∕ 48 … 32 ∕ 64 … 40 ∕ 80 … 48 ∕ 96 … 64 ∕ 128
0.1571 0.0785 0.0835 0.0885 0.1309 0.0654 0.0696 0.0738 0.0982 0.0491 0.0522 0.0553 0.0785 0.0393 0.0418 0.0443 0.0654 0.0327 0.0348 0.0369
3 ∕ 6 4 ∕ 8
5 ∕ 10 6 ∕ 12 8 ∕ 16
0.0491 0.0393
… … … … … …
0.0277 0.0221 0.0138
0.3142 0.1571 0.1671 0.1771 80 ∕ 160
10 ∕ 20 12 ∕ 24
0.2618 0.1309 0.1392 0.1476 128 ∕ 256 0.0246
16 ∕ 32 … … … … … Tooth Numbers.— The American National Standard covers involute splines having tooth numbers ranging from 6 to 60 with a 30- or 37.5-degree pressure angle and from 6 to 100 with a 45-degree pressure angle. In selecting the number of teeth for a given spline application, it is well to keep in mind that there are no advantages to be gained by using odd numbers of teeth and that the diameters of splines with odd tooth numbers, particularly internal splines, are troublesome to measure with pins since no two tooth spaces are dia- metrically opposite each other. 0.1963 0.0982 0.1044 0.1107 Types and Classes of Involute Spline Fits.— Two types of fits are covered by the American National Standard for involute splines: the side fit and the major diameter fit. Dimensional data for flat root side fit, flat root major diameter fit, and fillet root side fit splines are tabu- lated in this standard for 30-degree pressure angle splines, but for only the fillet root side fit for 37.5- and 45-degree pressure angle splines. Side Fit: In the side fit, the mating members contact only on the sides of the teeth; major and minor diameters are clearance dimensions. The tooth sides act as drivers and centralize the mating splines. Major Diameter Fit: Mating parts for this fit contact at the major diameter for centraliz ing. The sides of the teeth act as drivers. The minor diameters are clearance dimensions. The major diameter fit provides a minimum effective clearance that will allow for con tact and location at the major diameter with a minimum amount of location or centralizing effect by the sides of the teeth. The major diameter fit has only one space width and tooth thickness tolerance which is the same as side fit Class 5. A fillet root may be specified for an external spline, even though it is otherwise designed to the flat root side fit or major diameter fit standard. An internal spline with a fillet root can be used only for the side fit. Classes of Tolerances.— This standard includes four classes of tolerances on space width and tooth thickness. This has been done to provide a range of tolerances for selection to suit a design need. The classes are variations of the former single tolerance which is now Class 5 and are based on the formulas shown in the footnote of Table 4. All toler- ance classes have the same minimum effective space width and maximum effective tooth thickness limits so that a mix of classes between mating parts is possible.
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