Assembly; Attach The Rail To The Motor Unit; Set The Belt Tension - Security + Elite 3885C Owner's Manual

ASSEMBLY STEP 1

Attach the Rail to the Motor Unit

To avoid installation difficulties, do not run the
garage door opener until instructed to do so.
• Remove the bolt and lock nut from the top of the
motor unit.
• Place rail onto the bolt mounted on the motor unit
and align the back hole with the hole in the top of
the unit.
• Fasten rail with the washered bolt and lock nut
previously removed. Tighten securely. Remember
to use only these bolts/fasteners! Any other
bolts/fasteners will cause serious damage to The Chamberlain Group, Inc.
Liftmaster Synchro Drive
the opener.
Spring Trolley Nut Assembly
3/5/92 - 5/16 /92 - 5/21/92 - 6/2/92
• Cut tape from rail, belt and styrofoam.
6/11/92
• REMOVE STYROFOAM.
• Position belt over the motor unit sprocket.
ASSEMBLY STEP 2

Set the Belt Tension

• By hand, thread the spring trolley nut on the
threaded shaft until it is finger tight against the
trolley (Figure 1). Do not use any tools.
• Insert a screwdriver tip into one of the nut ring
slots and brace it firmly against the trolley
(Figure 2).
• Place a 7/16" open end wrench on the square
end. Rotate about 1/4 turn until the spring releases
and snaps the nut ring against the trolley
(Figure 3).
This extends the spring for optimum belt tension.
Trolley Nut Ring
BEFORE
1" (2.5 cm)
Figure 3
Trolley
Nut Ring
AFTER RELEASE
1-1/4" (3.18 cm)
WARNING
CAUTION
To avoid SERIOUS damage to opener, ONLY use
bolts/fasteners mounted in top of motor unit.
USE ONLY THIS
TYPE AND SIZE
BOLT
Figure 1
Figure 2
6
Washered Bolt
5/16"-18x1/2"
Lock Nut
Styrofoam
Rail
Hole
Trolley
Threaded
Shaft
Spring/Trolley Nut
Nut
Ring
Square
End
Trolley
Threaded
Shaft
Nut Ring
Slots