We are going to consider this diagram in two
ways.
1. The 15 tooth
gold gear on the right is the driving gear.
The 20 tooth grey driven gear turns more slowly than the driving gear,
since one turn of the gold gear has turned the grey gear through only 15/20th
of its cycle.
However, if we call the push from one tooth of the gold gear "one push",
then each revolution of the grey gear has 20 pushes, so that the force
has been multiplied.
This gear train acts as a force multiplier.
2. The grey gear is now the driving gear.
The gold driven gear completes one revolution before the grey one does.
However, the number of pushes per axle revolution has decreased from
20 to 15.