Brake mechanism for spool

Abstract

A brake mechanism for controlling a ribbon spool wherein a brake member is disposed in braking relationship with the spool for retarding rotation thereof. The brake member has a brake actuator projecting therefrom. An elongated follower pivotally bears against the spool to follow any decrease in the diameter thereof. The follower has an adjustment member which creates a cammed relationship with the brake actuator for progressively moving same and decreasing the brake torque as the follower pivotally moves in response to a decrease in spool diameter. This adjustment member is positioned to impose either a zero or a minimum torque on the brake member when the spool is empty. When in this empty-spool position, the adjustment member can be initially adjusted in a direction substantially parallel to the radial direction of the brake actuator so as to not affect this zero or minimum brake torque. However, this adjustment causes the adjustment member to swing about a different arc when the follower pivots due to being engaged with the full ribbon spool, whereby the movement imposed on the brake actuator is correspondingly changed so that the maximum brake torque for any selected spool diameter can be adjusted without affecting the zero or minimum torque for the empty-spool condition.