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Rev. A.3, 5/00 Page- 12
In the case of very tall and large gates, a levering problem can exist. By this we mean that an
intruder may be able to flex the gate enough to take up the slack in the strike mounting screw
and then lever off the strike plate. If the installer or user determines that this may happen, a
single Magnalock will not provide adequate security and two must be used, typically at the top
and bottom of the gate.
Figure 11 (above) shows preferred special techniques for Magnalock mounting on 3 types of
gates. The first drawing shows a
single swinging gate. The general technique follows the
principles discussed above but the use of Securitron's Z bracket which creates a neat
installation is also shown. Note that in some cases, the post which mounts the magnet is
hollow. It is possible to use the "F" version (without conduit fitting) and pull the wires through
the post which may yield a neater and more secure installation.
The second drawing shows a
double swinging gate which presents a unique problem. The
Magnalock is mounted in the same general way as on a single swinging gate but since both
arms move, an intruder pushing on the gate exerts a shearing force on the Magnalock.
Electromagnets are not at all strong in this orientation of attack. Therefore, as the drawing
shows, Securitron's Z bracket should be used with an interference piece which blocks the
shearing effect while the strength of the magnet blocks one arm moving while the other is
stationary. For this technique to work, the motorized operator must be
coordinated which
means that one arm must move first to clear the interference piece before the other arm starts
moving. Gate operators can normally accomplish this.
The final drawing on Figure 11 shows a special mounting technique for
sliding gates. We
recommend the use of the "GF" type magnet and two 3" angle brackets (available from
Securitron) for a neat installation. A special strike mounting technique is shown in the drawing
which improves reliability. The problem is that if the strike is mounted normally to the angle
bracket and the gate is a powerful one which slams shut, the magnet may be impacted to the
point where its mounting screws loosen or the bracket bends. The strike mounting technique
that is shown creates a "shock absorber" effect by the use of lock nuts at the rear of the strike
and the rear of the bracket together with a spring. A through hole (rather than tapped) is
drilled in the angle bracket mounting the strike and extra long roll pins are used. When the
gate closes, the strike moves in against the spring which is the shock absorbing action.
2.7 USE OF DRESS COVERS
Once the physical installation is complete, you may want to consider the use of a dress cover.
Dress covers are metal stampings which slip over the magnet body and are affixed with
permanent double stick tape (supplied). The dress cover accomplishes three functions: First,
it makes for a more attractive installation by concealing the strike plate and mounting holes.
All that is seen is an attractive rectangular form on the door. Second, the cover provides an
extra degree of tamper proofing and finally it allows easy alteration of the finish for
architectural compatibility. Dress covers are available in clear aluminum, satin black aluminum,
polished stainless and polished brass finishes.
Double dress covers are also available for installations on double doors. In this case, the cover
fits over two locks so long as they are not separated by more than 2" (50mm). Double dress
covers have all the advantages mentioned above and in addition produce the appearance of a
single device which inside is really two. Consult the catalog for dress cover part numbers.
2.8 TAMPER PROOFING THE MAGNALOCK
In situations where vandalism is expected, the Magnalock should be protected from tampering.
The magnet itself is inherently tamper-proof being totally sealed. The magnet mounting screws
are vulnerable in that the magnet can be dismounted if the screws are loosened. The allen
holes on the screws can be filled with a potting compound, such as Devcon, or silicone.
Alternately, the entire hole in the magnet where the screw heads fit could be filled. Butyrate
caps are supplied to close the mounting holes. These provide some tamper proofing as they
can't be removed by hand, but can be pried out with a tool. Regarding the strike plate
mounting screw, it is covered by the strike when the magnet is energized. If tampering is
anticipated when the door is open, the screw socket head may be filled.
Another possibility is that
Securitron inventories special tamper proof screws for both
magnet and strike mounting. These screws are identical allen head types except that it
requires a special key to install and remove the screws. It is unlikely that a vandal would have
access to this type of key. Securitron optionally supplies the tamper proof screw sets with keys
both in the form of a manual allen wrench and in a bit key usable with a drill.