RADIOLOGICAL DETECTION RESISTANT COMBINATION LOCK

A combination lock of the type adapted for changing of the combination by a change key, a lock case housing, a stack of a plurality of tumbler wheels loosely journaled on a tumbler post for rotation about its axis and each including an annular outer rim portion and an inner annular hub portion having teeth releasably intercoupling the hub portion and rim portion at any of a plurality of relative angular positions. The rim portions of the tumbler wheels have specially shaped peripheral gates to receive confronting portions of a fence on the fence lever when the tumbler wheels are properly aligned. The tumbler post is supported within the tumbler wheel hub portions for nonrotatable axial movement to shift the hub portions axially relative to the outer rim portions between coupled and decoupled relation. An actuator is activated by rotation of the change key for axially moving the tumbler post and the tumbler wheel hub portions to shift the hub portions to decoupled relation for combination change and a secondary change fence number is moveable into inserted relation in the tumbler wheel gates and retractable therefrom upon movement the of the actuator to selectively hold the rim portion against rotation.