Abstract: A cylinder lock with a removable plug incorporates a series of spring biased combinating disc tumblers which cooperate with a first key in normal lock operation. An additional, unbiased control tumbler at the end of the plug cooperates with a retention flange associated with the cylinder to retain the plug against removal from the cylinder while permitting rotation of the plug in the cylinder. The control tumbler includes a notch for receipt of the first key as well as a second, plug removal key. The first key acts against one edge of the notch to displace the control tumbler into a position which ensures that the tumbler will remain engaged with the plug retention flange regardless of the orientation of the plug.

Abstract: An improved locking system for a series of vertical arrayed drawers includes a plurality of dogs mounted on a pivot rod attached to a panel adjacent the series of drawers. The dogs pivot in response to an actuator plate which is driven by cam drive associated with movement of the drawers. The mechanism is useful for operation of a series of drawers in vertical array to maintain all of the drawers closed or to maintain selected drawers in a closed condition.