Patent ID: 7413269

Claim:
A three-stage ball bearing slide and synchronous system therefore, comprising a mobile track, a carrier track and a fixed track; a slide aid being disposed between the mobile track and the carrier track and between the carrier track and the fixed track to facilitate extending the tracks, a positioning structure being disposed on the mobile track to prevent the mobile track from disengaging from the carrier track when pulled to its extreme, and the carrier track being secured when pulled to its extreme in relation to the fixed track, and characterized in that: the carrier track having an arch center in cross-section; a dancer being pivoted to a rear end of the carrier track, the dancer having a plate flushed against the arch center of the carrier track, an indention being formed in a rear end of the plate, a wall facing an inner side of the mobile track being formed in the front of the indention, a resisting bit facing the fixed track being formed in the rear of the indention to pass through the carrier track, a rear end of the wall and a front end of the resisting bit facing each other and expanding outwardly at a certain oblique, an elastic member being connected to the carrier track, another end of the elastic member being connected to one side of a pivoted end of the dancer, the dancer being subject to an elastic pull and automatically maintaining a constant swing; a protruding tongue being provided on the inner side of the mobile track in relation to a space defined by the indention of the dancer; a compression bit protruding from an inner side of the fixed track in relation to the rear end of the carrier track when pulled out, an edge of the compression bit being provided with a shallow slot in relation to the resisting bit of the dancer; the mobile track by having its protruding tongue to extend into the indention of the dancer and uphold against the wall of the dancer to link the carrier track to be pulled out; the fully extended to its extreme by the carrier track being secured by upholding with the resisting bit of the dancer engaged with the shallow slot of the compression bit on the fixed track; the positioning being immediately released when pushed by an external force on the carrier track; and the dancer being linked by the retracted mobile track to release the dancer restricted by elasticity.