Repair a Worn
Mortise Cylinder
Here we are with a worn mortise cylinder. The cylinder exhibits all the symptoms of loose
cam screws. The key enters and
operates the cylinder properly,
but when the key is pulled, the
plug moves out with the key far
enough to prevent the combinat-ing pins from exiting the plug
and sliding up into the upper pin
chambers. The key cannot be removed without applying pressure
on the face of the plug. When
pressure is applied to the face of
the plug, the key is released and
slips easily from the plug.
The problem is wear in the
Raised Ring at the rear of the
cylinder, allowing too much axial
movement of the cylinder plug.
Tightening the cylinder cam
screws may improve the key pull,
but there remains a catch when
the key is being pulled from the
cylinder.
This is an easy problem to
remedy. It doesn’t even require
disassembly of the cylinder.
Remove the cylinder cam
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Figure 1.
screws and cam. Lay the cylinder
on a flat surface, causing the plug
to be pushed up. “Flat File” the
rear of the plug, as you see in
figure 1, to bring the length of the
plug down to meet the surface of
the raised ring. The object is to
file only the plug without touch -
ing the raised ring. File carefully,
holding the file as flat as possible
to the rear of the cylinder. Reinstall the cam and cam screws.
Test the cylinder for proper
operation and satisfactory key
pull. If there is any binding of the
plug, as it is rotated through its
360° of rotation, Rotate the plug
to the position of the bind, and
tap the cam lightly with a small
hammer. In most cases, this will
eliminate the binding.
g
Repair a Worn Rim Cylinder
Wear, between the cylinder
plug retainer and cylinder is a
common cause for complaint.
This problem usually occurs on
out swinging doors with latch, or
emergency exit hardware. The
customer inserts and turns the
key to release the latch, then
tugs on the key to pull the door
open. This will cause wear between the plug retainer and the
rear of the lock cylinder. After a
few years of this treatment, the
call comes in: “I can’t get the key
out of the lock.”
The key is not jammed in
the lock, as it still rotates freely.
The problem is that the plug is
moving outward, as the key is
pulled. A misalignment of the
“top pin” holes and the cylinder
plug prevents the key from being
removed. Holding the plug in
the cylinder, while pulling the
key, instantly releases the key.
Axial free play movement of the
plug prevents the key from being
removed. The repair is to remove
the axial free play of the plug.
To repair this cylinder, it is
necessary to reduce the axial
