Method for sensing cartridge decoupling in tape drive

An apparatus and method for controlling the movement of an elevator mechanism in a tape drive system. The mechanism of the present invention employs a tachometer to detect the magnetic decoupling of a cartridge from a cartridge reel motor. A holding torque is placed on the cartridge reel motor. A voltage or current ramp is supplied to the elevator mechanism, wherein the elevator mechanism raises and magnetically decouples the tape cartridge from the cartridge reel motor. As the coupling force is broken, the torque placed on the cartridge reel motor causes the motor to turn. The tachometer detects the magnetic decoupling of the cartridge from the cartridge reel motor by sensing the angular displacement of the motor. In response, the controller decreases the voltage or current ramp to adapt to the load reduction on the elevator mechanism, and thereby more smoothly continue the elevator motion.