end of this radial extension is thickened as shown at 151g to a sufficient extent to make contact during rotation with the projection or tab 173 on the adjacent face of the adjacent lock wheel 161 the lock wheels 161 and 163 may be the same as the lock wheels 61 and 63 in the first embodiment and operate in the same way the thickened portion or lug 151g on the drive wheel 151 thus serves the same purpose or function as the screw 59 in the first embodiment in that it serves to drive the wheel 161 and causes this wheel to drive the next wheel 163 just as in the first embodiment the difference is that this driving lug 151g in the second embodiment is in fixed position and cannot be moved to various positions to alter the combination the way the screw 59 can be shifted to different holes 51c in the first embodiment another difference between the two embodiments is in the latch mechanism in the first embodiment the latch base plate 31 housing 33 latch bolt 35 slide 37 and the springs 39 and 45 were all separate parts which had to be assembled around the bushing 17 because one end of the spring 39 was held in place by contact with the flat side of the bushing as seen in fig2 in.