Assembly; Attach The Rail To The Motor Unit; Set The Belt Tension - Chamberlain 3585CS 3/4HP 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 opener.
• Cut tape from rail, belt and styrofoam.
The Chamberlain Group, Inc.
Liftmaster Synchro Drive
• REMOVE STYROFOAM.
Spring Trolley Nut Assembly
3/5/92 - 5/16 /92 - 5/21/92 - 6/2/92
• Position belt over the motor unit sprocket.
6/11/92
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)
To avoid SERIOUS damage to opener, ONLY use bolts/
fasteners mounted in top of motor unit.
USE ONLY THIS
TYPE AND SIZE
BOLT
Spring/Trolley Nut
Figure 1
Figure 2
6
Washered Bolt
5/16"-18x1/2"
Lock Nut
Styrofoam
Rail
Hole
Trolley
Threaded
Shaft
Trolley
Threaded
Shaft
Nut
Ring
Square
End
Nut Ring
Slots