Page 218 - Gear Technology Solutions

15.7 Summary

Spline misalignment is a common problem, which is present in any spline con-
nection. Very small misalignments in the single angular minute range can be
compensated with increased backlash. Increased backlash is not always an
acceptable solution because of the unbalancing and the compromising of the
load transmission capability. Barrel shaped spherical splines are common. The
design calculation of the face radius and the root-based relief radius has been
shown in this chapter. A disadvantage of a barrel shaped spline is the increase
of interference fit when misalignment is applied, and the reduced contact zone
even without any misalignment.

If the misalignment is known, then the alternative of a roof top spline appears
an elegant solution because it compensates for the misalignment perfectly and
does not lead to an increase of interference. The calculations for dimensioning
a roof top spline are shown in this chapter. The roof top spline will, in operating
conditions without misalignment, ensure a contact surface area without load of
about 30% of the spline flank surface. In the case of the predetermined misa-
lignment, the contact area, in case of no load or low load, will be 50% of the
flank surface and increase under load accordingly.

15.8 Literature

[1] AGMA 945-A18 “Splines - Design and Application”, published by the Ameri-
can Gear Manufacturers Association, November 2018

[2] ANSI B92.1 Standard, Involute Splines and Inspection, published by So-
ciety of Automotive Engineers, 1996

[3] ISO 4156-2005 “Standard, Straight cylindrical involute splines - Metric mod-
ule, side fit”, published by International Organization for
Standardization, 2005

[4] ISO 14 “Standard, Straight-sided splines for cylindrical shafts with
internal centering - Dimensions, tolerances and verification”,
published by International Organization for Standardization,
1982

[5] Hong, J. “Load distribution analysis of clearance fit spline joints using
Talbot, D. finite elements”; Mechanism and Machine Theory, Vol 74,
Kahraman, A. 2014, pages 42-57

[6] Städeli, O “Toothed Couplings” Company Publication, MAAG, Zurich,
Switzerland, February 1987

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