| 摘要 |
An improved protective device for an ignition lock cylinder of a motorized vehicle comprising an armored cap arranged axially with and covering the cylinder end, the cylinder and cap adapted for mutual rotation about the cylinder axis to activate the ignition when a mating key is inserted through the cap to unlock the cylinder, the cap adapted to be rotated by hand to rotate the cylinder. The improvement comprises a torque-sensitive coupling adapted to be disposed in coupling relationship between the lock cylinder and cap. The coupling is constructed and arranged to transmit torque applied to the cap cylinder of a value below a predetermined maximum value selected to exceed normal torque applied to an unlocked cylinder by hand action of a vehicle operator. The maximum torque value is less than that needed to force rotation of the cylinder when the cylinder is still locked. The coupling is also adapted to disengage between the cap and cylinder when torque above the predetermined maximum value is applied. Whereby the cap and cylinder are positively related to prevent independent rotation of either during normal operation, e.g. to avoid damage to a key that has been only partially inserted into said cylinder, the cap being free to turn in uncoupled relationship with the cylinder when abnormal torque is applied to the cap, thereby to prevent rotation of the cylinder by force of a car thief. In another aspect, a device for aligning the cap and cylinder coaxially is provided, e.g. where a protective coupling is also employed.
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