GB993243A - Safe deposit box lock - Google Patents

Abstract

993,243. Locks. R. T. ELLIS. Feb. 27, 1962 [Feb. 27, 1961; Sept. 29, 1961], No 7595/62, Heading E2A. A lock for a safe deposit box in which a customer key and a guard key are used comprises a housing, a bolt 45 movable between extended and retracted positions, a first key nose 25 extending within the housing, a plurality of tumblers 70 movable upon operation of a key in the first key nose between a first position in which retraction of the bolt is prevented and a second position in which retraction of the bolt is permitted, and interference means acting between the bolt and the tumblers and being movable to one position in which the bolt, during assembly of the lock, can be moved to its retracted position whilst the tumblers remain in their first position, and movable to a further position in which the bolt, upon subsequent operation of a key in the first key nose, can be moved to its extended position and thereafter cannot be retracted unless the tumblers are first moved to their second position by operation of a key in the first key nose. To retract the bolt 45, a guard key is first inserted into the nose 25 and rotated to engage the edges 85 of some of the floating primary tumblers 70 and to lift them so that their slots 102 are aligned with the pin 99 of a spring-loaded lever 95. The pin 99 springs into the aligned slots 102. A second guard key is inserted into the nose 25 which engages in a reset cam 106 and is rotated to align the remaining primary tumblers 70 so that the pin 99 springs fully into all the slots 102, causing the lever 95 to pivot and draw its blocking end 100 out of alignment with the secondary bolt lug 87 (see Figs. 1 and 5). The customer key is then inserted in the nose 24 and rotated to lift the tumblers 70, through their engagement with secondary tumblers 75, to position their slots 74 opposite the primary lug bolt 48. On further rotation of the customer key the cam plate 124 engages with the projection 128 of the bolt 45 to retract it. To lock the bolt the customer key is rotated anticlockwise, the cam 124 engaging in the surface 131 of the bolt 45 to re-extend the bolt end 46; during this motion the primary tumblers 70 are lowered. The guard key is rotated anticlockwise causing the reset cam 106 to engage the surface 116 of trip dog 110 to press it against the stop 112. Movement of the stop 112 causes the lever 95 to pivot and retract the pin 99 from the slots 102, thus moving the blocking end 100 into the position in Fig. 3 to prevent movement of the bolt 45. The tumblers 70 are provided with randomly spaced holes 140 so that the resonance characteristics differ. During assembly of the lock, when the cover plate is removed, the bolt release lever 95 is pivoted clockwise and the bolt 46 retracted manually so that a rod 101 rides over the surface 138 of the bolt extension, simultaneously bolt lug 48 pivots anticlockwise and rests on the tumblers 20 held by a spring 58. Specification 993,242 is referred to.