A.K.A Timing Spring

The front spring which is also called the timing spring
or the control spring has a lot to do with the speed of
your machine. A harder front spring will make your machine
faster because the front spring absorbs shock or
recoil when the armature bar is retracted after a cycle.
Because the armature bar gets pulled down by magnets
then released when the magnets turn off, the rear
spring has some tension on it and it bounces back up.
When the rear spring bounces back up it has the armature
bar and front spring attached to it. The front
spring will shoot upwards and it will touch the contact
point. If the front spring is soft it will absorb a lot of energy
and flex. This flex will actually slow the cycle down
while the circuit is re-closing and starting the cycle
again. If you have a harder front spring then there will
be less flex and the circuit can start over a lot faster.