Ok, with permission by db, here are the pics,
No bypass discussion, please.
This is a vintage BELLLOCK.
The key has "BELLLOCK PATENTED", a number, and
The Eagle Lock Co., Terryville, Conn. Made In U.S.A
stamped on it.
The lock itself has the same number and no other markings.
It is BTW *not* an automotive lock.
This is the lock with the keys (it came with a set of 2 keys, both are the same):
The 2 screws are not original of course, in those places were 2 rivets.
When opened, you can see the deadbolt that can be moved by turning the plug by 90 degrees:
And now comes the most interesting part (in my opinion):
The plug (on the right) has *two sets* of wafers that stick out of the plug while no or the wrong key is inserted. One set of (5) wafers fits to one side of the keys I have, and it interacts with the 4 sets of cuts in the housing that you can see as an off-centered "cross". (From this you can also see that the key can be removed in 2 positions, 0 and 90 degrees.)
However, the other set of (4) wafers does not fit to the other side of the keys. But I can still turn the plug, because the housing has cuts all around in the layers where these wafers are. So this second set of wafers does not block the plug from rotation.
It does however block the plug from pushing it further into the lock body.
There is a strong spring and a washer behind the plug:
Now my theory - I believe that this is used for masterkeying:
On the change keys, side 1 is cut to the particular lock, and side 2 is cut to a dummy pattern.
On the master key, it's the opposite - side 2 is cut to match the (4) wafers that usually prevent pushing the plug into the lock. When the master key is inserted, the user pushes the plug into the lock, then the (5) wafers do not block anymore, and the plug can be turned.
An interesting concept for masterkeying.
Finally, this is a picture of the plug - with the (5) wafers on side 1 still inside, while the (4) wafers on side 2 and their springs have been taken out. The long narrow strip of brass is the retainer that keeps the wafers inside:
I hope you like it
Cheers,
mh