#Makerbot #Patents
A bearing that provides contact force to engage a filament with a drive gear has a movable axis that can be controllably moved toward and away from the drive gear in order to engage and disengage the filament. A bearing is spring-biased toward the drive gear, and a bistable lever mechanism is provided with a first stable position in which the bearing is engaged with a filament and a second stable position in which the bearing is disengaged from the filament. By providing a mechanism that locks in both positions, loading and unloading of filament can be facilitated.