Method and apparatus for parking and releasing a magnetic head

An information storage device (10, 510, 610, 710) includes a cradle (12, 512, 612, 712) which can removably receive a cartridge (11, 411, 511, 611, 711). The cartridge has a sealed housing (59) which contains a rotatably supported disk (91, 326-327), and a pivotal actuator arm (101) that supports a magnetic head (107, 331-334) for movement adjacent the disk. When the cartridge is removed from the cradle, the head is moved to a parked position with respect to the disk, in which a magnetically permeable part (116) on the actuator arm is in close proximity to a magnetic arrangement (141) disposed within the housing. The magnetic arrangement exerts a strong magnetic force that resists movement of the arm and head away from the parked position. The cradle has a shunt (142) which, when the cartridge is removably inserted, interacts with the magnetic field through a wall of the sealed housing, in a manner which reduces the effective magnetic force that tends to retain the arm and head in the parked position.