Tumbler wheel for combination lock

The lock 20 has a stack of say three or four tumbler wheels 34-37 rotatable on a hollow tumbler post, assembly 22 and each wheel has an inner hub portion 38 with an opening 38a for journalling on the assembly 22 and an outer rim portion 39 connected with the hub portion 38 to permit combination change. The portions 38, 39 are provided with interfitting teeth 47, 48 and the centre opening surface of portion 39 has a retaining groove 39a to receive a spring wire 49 which forms a many-sided polygon and a part of which is an interference fit with a ramp formation 38a on portion 38, which formation 38a has a pair of surfaces converging to a crest. The portion 38 is moved to elastically deform wire 49 from the position of Figure 7A to the position of Figure 78 and vice versa to give snap action as the wire 49 is distorted over the crest and releases itself. In the released position of Figure 7B portion 38 may be rotated to change combination.