Abstract: A pick-resistant-multiple-pin-tumbler cylinder for a lock is disclosed, the principal embodiments of which include an integral, key-displaceable, booby-trapped, lock-up element within the cylinder shell, and slidably mounted in relation to a portion of the rotationally displacable cylinder plug and in which the lock-up element contains a T-shaped peripheral notch which engages and receives a fixed pin or lug projecting from the bore and is thus both slidably and rotatively received in the shell and spring pressed axially for engagement of its shaped notch with the pin, whereby the peripheral dimension of the notch limits the rotation of the plug to a small angle until the lock-up trapping element is thrust towards the rear of the cylinder through the insertion into the plug's keyway of a properly profiled key, imparting a predetermined linear displacement effecting disengagement of the lock-up element.

Abstract: A pick-proof lock of the cylinder type primarily intended for use in doors, which includes a locking collar or sleeve slidably mounted around a portion of the cylinder plug and which contains a notch to receive a spring pressed pin which is contained in the cylindrical shell of the lock. The collar or sleeve is slidably and rotatively received in the shell and spring pressed for engagement of its notch with the pin, whereby rotation of the plug within the shell can only be accomplished to effect unlocking of the lock when the spring urged locking collar has been displaced rearwardly of the lock from a projected locking position to a retracted unlocking position. Since the locking collar and the pin which locks said collar to the shell do not communicate with the keyway of the plug, tools and other instruments normally used for picking locks are ineffective in picking the lock.

Abstract: A pick-proof lock of the cylinder type primarily intended for use in doors, which includes a locking collar or sleeve slidably mounted around a portion of the cylinder plug and which contains a notch to receive a spring pressed pin which is contained in the cylindrical shell of the lock. The collar or sleeve is slidably and rotatively received in the shell and spring pressed for engagement of its notch with the pin, whereby rotation of the plug within the shell can only be accomplished to effect unlocking of the lock when the spring urged locking collar has been displaced rearwardly of the lock from a projected locking position to a retracted unlocking position. Since the locking collar and the pin which locks said collar to the shell do not communicate with the keyway of the plug, tools and other instruments normally used for picking locks are ineffective in picking the lock.