Page 208 - Gear Technology Solutions

number from the DIN/ISO table of preferred modules, then the rounding to
2.0mm is proposed.

rounded module: mFinal = 2.0mm

This module rounding is without any tangible consequence if the spline shaft
as well as the sprocket spline are together in the design and manufacturing
planning stage. If the sprocket design is done for an aftermarket purpose, and
has to fit on an OEM shaft spline, then the working pressure angle at the refer-
ence diameter might show some mismatch. In the present case the rounding
was only small and pressure angle mismatch will be within an acceptable tol-
erance.

With the new, rounded module the previously calculated addendum and de-
dendum values have to be preserved. However, the original factors for the cal-
culation of addendum and dedendum (hK=0.45*m and hF=0.60*m) have
changed by the module rounding. This fact is not relevant, because the mm-
value of the sum of addendum and dedendum remain the same, as well as the
top-root clearance.

After the module rounding, the pitch diameter and the profile shift factor have
to be recalculated:
d0Final = mFinal*z = 24.00mm

xFinal*mFinal = (d0Final – dRef)/2

xFinal = xInternal = (d0Final – dRef)/(2*mFinal) = –0.572

The spline set always has a V0 profile shift relation which means:

xInternal + xExternal = 0

and xExternal = –xInternal = +0.572

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