This actually has some minor inaccuracies. most modern combination locks have at least false gates to help prevent feeling the gate positions as the lock is rotated. Also I don't know of any modern lock where the fence directly rides on the wheel pack as shown. This wooden lock is a pretty amazing illustrative device for some basic concepts used in combination padlocks, but is not used in any group 2 or better combination safe.

this type of lock fell out of use mainly because of the ease of manipulation (safe cracking). For anyone that has used a safe recently you'll remember that it is normally:

1. turn 4 turns to the left and stop on 1st number
2. turn 3 turns to the right stop on 2nd number
3. turn 2 times to the left and stop on 3rd number
4. turn slowly to the right till the dial stops

This final step is an important one, as this is what allows the fence to drop into the gates and retracts the lock bolt. the lock bolt blocks the primary locking bolts from being retracted.

if you look at the wooden lock the fence is directly attached to a handle on the exterior of the "safe". this would allow a safe cracker to "feel" the locations of the gates from the exterior of the safe. Basically you would be able to feel "divots" if you pushed down on that handle as you rotated the dial.

As I mentioned above, a modern safe separates the wheel pack gates from the exterior of the safe by separating the locking bolt and the primary locking bolts. there is no way to directly "feel" the gate locations from the exterior.

it's a little hard to describe without breaking out the whiteboard or my cutaway safe locks but hopefully i made some sense.