Page 207 - Gear Technology Solutions

The tooth proportions addendum and dedendum relate the depth to the still
unknown module:

Depth = hK + hF = 0.45*m + 0.60*m

This relationship allows to calculate a module of:

m = Depth/1.05 = 1.905mm

With the known module it is now possible to calculate addendum and deden-
dum:

Reference addendum: hK = 0.45*m = 0.857mm

Reference dedendum: hF = 0.60*m = 1.143mm

Both dimensions, hK and hF are reference values which split the tooth depth
into the reference addendum and the reference dedendum. This means that
neither of the values is related to the pitch circle. The pitch diameter is calcu-
lated as for a standard spur gear by multiplying the module with the number of
teeth:

d0 = m*z = 22.857mm

It can be recognized that the pitch diameter is smaller than the minor diameter
of the spline. Because the spline is not a meshing gear member, there is no
working pitch diameter, and the meaning of the pitch diameter is primary im-
portant for the choice of the hob cutter and/or the broach. However, it is mean-
ingful to calculate a reference diameter which separates the reference adden-
dum and the reference dedendum:

dRef = dMinor + 2*hF = 26.286mm

The difference between the pitch diameter and the reference diameter can
now be used to calculate the profile shift, which is:

x*m = (d0 – dRef)/2

or: x = (d0 – dRef)/(2*m) = –0.9

The initially calculated module of 1.905mm will not allow utilizing a standard
broach for the internal sprocket spline. If the module is now rounded to a

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