Related Resources: gears

Involute Spline ANSI B92.1 Equations and Design

Gear Design and Engineering

American National Standard Involute Splines - These splines or multiple keys are similar in form to internal and external involute gears. In general manufacturing external splines is facilitated either by hobbing, rolling, or on a gear shaper, and internal splines either by broaching or on a gear shaper. The internal spline is held to basic dimensions and the external spline is varied to control the fit. Involute splines have maximum strength at the base, can be accurately spaced and are self-centering, thus equalizing the bearing and stresses, and they can be measured and fitted accurately.

Equations for Involute Spline Basic Dimensions ANSI B92.1-1970, R1993

 Term Symbol 30 deg φD 37.5 deg φD 45 deg φD Flat Root Side Fit Flat Root Major Dia Fit Fillet Root Side Fit Fillet Root Side Fit Fillet Root Side Fit 2.5/ 5 - 32/ 64 Pitch 3 /6 - 16 /32 Pitch 2.5/ 5 - 48/ 96 Pitch 2.5/ 5 - 48/ 96 Pitch 10/ 20 - 128/ 256 Pitch Stub Pitch Ps 2P 2P 2P 2P 2P Pitch Diameter D N/P N/P N/P N/P N/P Base Diameter Db D cos φD D cos φD D cos φD D cos φD D cos φD Circular Pitch p π/P π/P π/P π/P π/P Minimum Effective Space Width sv π/(2P) π/(2P) π/(2P) (0.5π + 0.1) / P (0.5π + 0.1) / P Major Diameter, Internal Dri (N + 1.35)/P (N + 1)/P (N + 1.8)/P (N + 1.6)/P (N + 1.4)/P Major Diameter, External Do (N + 1)/P (N + 1)/P (N + 1)/P (N + 1)/P (N + 1)/P Minor Diameter, Internal Di (N - 1 )/ P (N - 1 )/ P (N - 1 )/ P (N - 0.8 )/ P (N - 0.8 )/ P Minor Dia. Ext. 2.5/5 thru 12/ 24 pitch Dre (N - 1.35)/ P (N - 1.8)/ P (N - 1.3)/ P … 16/ 32 pitch and finer (N - 1.2)/ P 10/ 20 pitch and finer … (N - 1 )/ P Form Diameter, Internal DFi (N + 1) / P + 2cF (N + 0.8) / P - 0.004 + 2cF (N + 1) / P + 2cF (N + 1) / P + 2cF (N + 1) / P + 2cF Form Diameter, External DFe (N - 1)/ P - 2cF (N - 1)/ P - 2cF (N - 1)/ P - 2cF (N - 0.8)/ P - 2cF (N - 0.6)/ P - 2cF Form Clearance (Radial) cF 0.001 D, with max of 0.010, min of 0.002

π = 3.1415927

Note: All spline specification table dimensions in the standard are derived from these basic formulas by application of tolerances.