651,187. Permutation locks. SARGENT & GREENLEAF, Inc. Sept. 21,1949, No. 24296. Convention date, March 26. [Class 441 In a permutation lock of the type comprising a series of coaxial discs set to align peripheral notches by movements of a central control knob, a sliding bolt 23, Fig. 2, is adapted to be withdrawn by a lever 24 pivoted thereto, having a nose 28 to engage in a recess 12a in the wheel 12 connected to the control knob 13, Fig. 1, by a sleeve 11 and driving the discs 6, 7 and 8. A cross bar 27 on the lever 24 is arranged to enter the aligned notches in the discs as the nose 28 engages the recess 12a, but this movement can be prevented by displacement of a slider 43 mounted on the face of the driving wheel adapted to bridge the notch 12a in one position and in the other position to project a tail piece 43d outside the circumference of the driver wheel 12 to engage stops 60a, 60b to limit the rotation. The slider is formed with arcuate ends so that when in the bridging position the driver 12 presents a smooth circumference to the nose 28 main taining the bar 27 out of contact with the discs. The slider is displaced by a gear wheel 46 engaging a rack 44 formed in an opening in the slider and controlled through the spindle 47 by a key or permutation lock. In operating the lock, the shaft 47 is first turned, e.g. by the key 53 shown in Fig. 1, to set the slider 43 in the bridging position, withdrawing the end 43d to permit full rotation of the driver 12. A lug on the driver engages a projection on the disc 8 which is similarly connected to the next, 7, and that to the last 6 so that the discs are successively set by to and fro rotation of the knob 13. When the discs and the driver are all correctly set the key is turned to move the slider so that the nose 28 engages in the notch 12a and rotation of the knob will then withdraw the bolt. The distance between the stop faces 60a, 60b is sufficient to allow this rotation when the tail 43d is projected. As a further protection against picking the discs are serrated at 100 and co-operate with serrations 101, Fig. 11, on the bar 27. A slightly flattened portion on the circumference of the driver 12 allows the bar 27 to engage the discs when the nose 28 is in this position. To frustrate any attempt to open the lock by forcing the spindle inwards, a rocker 31, Fig. 2, pivoted at 33 normally to retain a spring plunger 34 retracted, but arranged to release the plunger for engagement in a socket of the bolt on inward displacement of the lock spindle 11. In a modification, Fig. 11, the slider 73 (shown in the bridging position), is mounted between guides on the driver 72 and displaced to either position by a cam member 84 engaging in a shaped opening 83. It is retained in the bridging position by a ball catch 77.