can be used to
calculate an appropriate center distance based a given sum for the profile shift
coefficients.
The centre distance C{a} is the theoretical distance between the origins of the
pinion and gear on assembly. The plus button can be used to define an upper and
lower tolerance for the centre distance. The sizing button can be used to
calculate an appropriate center distance based a given sum for the profile shift
coefficients.
Tolerances for the centre distance can be defined using the 
next to the input
field. Normally the tolerances are defined symmetrically so one is positive and the
other is negative.
