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© Copyright 2006, Sargent & Greenleaf, Inc.
Model 6730, 6735, 6738, 6741 Mechanical Combination Lock
Troubleshooting/Dialing Diagnostics
coMBination changing Mistakes
The combination changing process presents a lot of opportuni-
ties for a lockout. Even for an experienced technician, a mental
lapse can cause minor or major headaches. Sargent & Greenleaf
key changeable locks come in two varieties: zero change and
regular change. A zero change lock uses a single index on the
dial ring to open the lock and to change the combination.
It’s impossible to choose the wrong index when setting new
numbers.
The regular change lock has a changing index approximately 8
1/5 numbers to the left of (or counterclockwise from) the opening
index. Presented with two choices, the chance of an error in
combination changing increases dramatically. You should
always check your combinations at least three times before
closing the safe door, so a momentary lapse of concentration
that nudges you into setting a new number on the wrong index
is caught while the error is merely an aggravation, rather than
a catastrophe. Safe owners and end users have been known to
be less cautious, however. It is also a good idea to check your
combination setting prowess by dialing the set numbers 1/2
number lower and 1/2 number higher than what you set. For
instance, if you set a combination of 22 - 67 - 38, you would
dial a trial combination of 21 ½ - 66 ½ - 37 ½. Next, dial a
trial combination of 22 ½ - 67 ½ - 38 ½. The lock should open
both times if you have done a good job of setting the combina-
tion and the lock components are all within spec and working
as they should. Some locks will let you dial as much as a full
number lower and a full number higher than what is set. This
is called "dialing tolerance." Without this tolerance, it would
be extremely difficult to dial open a mechanical lock.
A mistake in combination changing usually means one or more
wheels are 8 1/5 numbers lower than expected. Unfortunately,
we don’t know for sure which wheels are affected. Use the
chart, which follows to work seven combinations. If the problem
is indeed use of the wrong index, one of these possibilities
should work. A fifth of a number is pretty hard to keep track of
when dialing, so we will round the distance between the indices
off to an even eight numbers. Remember to oscillate the dial in
the lock’s contact area after working each combination.
CHANGING INDEX
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