GB410698A - Improvements in locks - Google Patents

Abstract

410,698. Locks; switches. SMITH, B. C., Pope, Mississippi, U.S.A. Dec. 4, 1933, No. 34079. [Class 44.] A lock controlled by a slider is provided with permutation mechanism which operates to block the bolt against withdrawal by the key if, in an attempt to pick the lock, the slider is lifted above the normal amount. The bolt can be withdrawn by the key only when the permutation discs have been reset. In the normal operation of the lock, the key 14 after insertion through a key-barrel 25 is turned clockwise first to raise the slider 28 out of engagement with a stop 19 on the casing, then to retract the bolt 10 by engagement with a shoulder 22, and finally to allow the slider to fall and engage behind the stop 19 to hold the bolt retracted. A projection 23 on the bolt prevents rotation of the key through a full 180� so that it cannot be withdrawn from the lock while the bolt is retracted. The bolt is formed in two parts and the head 10 is retracted through lugs 12, 15 when the tail 13 is retracted ; the head 10 is pressed outwards by a spring 17 co-operating with the lug 12 and a fixed lug 16 on the casing, which latter serves also to limit the outward movement of the bolt tail 13. The key 14, Fig. 7, has cut-away parts 33 and projections 34 to co-operate respectively with the slider 28 and the bolt, notches 36 being provided to receive the edges of the keyhole 26 in the lock casing as the key is turned. If, while the bolt 10 is shot, the slider 28 is raised more than its normal amount, the lower end 67 of a recess 66 therein engages with a pin 56 on a permutation disc 45 (rotatable on a spindle 40) to rotate the disc so that a notch 46 is removed from the end of a pivoted pawl 53 ; the pawl is thus lifted into the path of and blocks the upper end of a lever 50 which at its lower end engages with a recess 49 in the bolt tail so that the bolt is blocked against operation by the key. To reset the permutation disc 45, the slider 28 is raised by turning the key through 90� so as to disengage an arm 60 on the upper end of the slider from a notch in a second disc 44 to free it ; rotation of the disc 44 by a graduated knob 43 rotates the disc 45 by the co-operation of pins 57, 58 on the discs so as to bring the notch 46 under the end of the pawl 53 and the disc 44 can then be returned to bring its notch under the arm 60. A single spring 63, 64 mounted on a pin 62 is provided for the slider 28 and the pawl 53. As applied to the steering column of a motor vehicle, the bolt 10 engages with a hole 38 in the steering shaft F. The ignition circuit of the vehicle is closed when the key is inserted by the end of the key pressing in against a spring 76 a cylindrical plunger 74 of insulating material so that a conducting ring 77 thereon abuts against contacts 78.