Model 6730, 6735, 6738, 6741 Mechanical Combination Lock
Troubleshooting/Dialing Diagnostics
Broken Lever sPring
Although quite rare, a broken lever spring can produce the
same results as a stuck lever. If the lock is mounted right-
hand, gravity will tend to pull the lever into the wheel and drive
cam gates when they are all lined up properly. A left-hand
mounting configuration orients the lever so gravity works against
a successful safe opening. A non-forced opening requires you
to actually turn the safe upside down. When the weight of the
safe and its environment permit this, it’s a good solution. A
broken lever spring in a vertical-up or vertical-down mounted
lock can sometimes be overcome by dialing so all wheel gates
are under the fence and the drive cam gate is under the lever
nose, then vibrating the safe door with a dead blow hammer.
The dial will have to be moved a few numbers in the direction
which would normally retract the lock bolt after each blow, to
see if the lever has moved in the desired direction. Failing this,
the safe will have to be tipped on one of its sides to accom-
plish a non-forced opening.
The term “handing” can refer to either of two related, yet
distinct aspects of a combination safe lock. One describes
the orientation of the lock after it is attached to the safe
door. The hand of mounting is usually described as right-
hand, left-hand, vertical-up or vertical-down. It is easily
determined by viewing the lock body from the inside surface
of the safe door. If the bolt of the lock points to the right, the
lock is mounted right-hand. If the bolt points left, the lock
is mounted left-hand. A bolt pointing upward indicates a
vertical-up mounted lock, while a downward facing bolt signi-
fies a vertical-down mounted lock.
At one time, it was common to manufacture both right
and left-hand mechanisms. If a lock is mounted left-hand
and its lever fence is located at the top of the lock case,
it is a true left-hand constructed lock. Current production
locks are all, with the exception of some vault locks, true
right-hand mechanisms. Extensive laboratory and field
testing has shown the modern right-hand constructed lock
works equally well when mounted in any of the four common
orientations (RH, LH, VU, VD).
Loose cover screws
If the cover of a lock is loose enough, it can let the relock trig-
ger engage. This is easy to diagnose. After the combination
is entered and the dial is being turned to retract the bold, the
lock will stop about ten numbers before it usually does. For
instance, the 6730 normally stops at about 95 when the bolt is
fully retracted. If the relock trigger is set, it will stop at about
5. If, however, you are working with an unfamiliar lock or one
that has been mis-splined during installation, there is still
an easy method for diagnosing a tripped relock trigger. First,
determine the left contact point of the lock (the number which
comes under the opening index when the lever nose first comes
in contact with the left side of the drive cam gate). Now dial
the combination and turn to retract the combination lock bolt.
The dial will stop before bolt retraction. If the stopping point is
within one or two numbers of the left contact point, something
is preventing the bolt from moving into the lock case. It’s very
likely the relock trigger.
Before you decide to drill, try the following technique: While
exerting very light turning pressure on the dial in the unlocking
direction, firmly rap the door in the vicinity of the lock, using
at least a 2 lb. dead blow hammer (although a metal hammer
and block of wood can be substituted, the dead blow hammer
works best, delivering a much higher percentage of the impact
to the door, rather than bouncing back). Ideally, the shock
will momentarily bounce the lock’s cover up against the case,
resetting the relock trigger for a fraction of a second. If you
maintain light turning pressure on the dial, or try to time your
application of pressure with the hammer blow, the bolt will be
able to move into the case.
LEFT-HAND
VERTICAL-UP
VERTICAL-DOWN
RIGHT-HAND
17
© Copyright 2006, Sargent & Greenleaf, Inc.
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