Fichet Bauche "3-wheel" combination lock
This one has three wheels. There are also version with four. Each wheel is turned separately with the tip of a Fichet-Bauche key where it makes clicking sounds. So they are not used without a key lock. Each wheel has 20 different positions, so there are 20^3=8000 different and possible combinations. The wheels are reset by turning counter-clockwise where they stop at 0. For unlocking the clicks from this position in clockwise direction have to be counted. So "1" is certainly much more often used than "19". Photo 1 shows the lock locked. The forked locking element on the left is lowered and the bolt work is blocked. Photo 2 shows the lock unlocked. The locking element leaves a gap for the bolt work. Each wheel is round with one edge cut of. When all three cut-offs are correctly positioned the blocking element moves to the open position. On top of photo 3 there is the cut-of turned to the viewer and the lock is locked. On the bottom the cut-of is turned towards the blocking element and the lock is unlocked. The combination can be changed after unlocking the lock and turning a knob at the back.
The lock can be manipulated by sound and feeling.
Martin Hewitt, Investigator Chronicles of Martin Hewitt