Talk:Simpson planetary gearset

3 forward velocities vs 3 forward speeds
Using velocities vs speeds to describe the number of forward gear ratios of a transmission sounds more intellectual but is incorrect!

First of all, a planetary transmission has several gear ratios but has an infinte number of output speeds since the input speed can vary continuously from 0 to its maximum value.

Nevertheless, it has become common usage to refer to the various transmission gear ratios as speeds. Substituting velocity for speed is incorrect because velocity is a vector quantity with magnitude and direction whereas speed is a scalar quantity with just magnitude. The transmission output is angular rotation about a fixed axis. Specifying forward speeds resolves a any uncertainty of direction, therefore the output is correctly described by speed not velocity. 75.72.161.233 (talk) 14:14, 17 November 2022 (UTC)