Chamberlain CG40DM - Manual (Page 9)

9
To avoid SERIOUS damage to garage door opener,
use ONLY those bolts/fasteners mounted in the top of
the opener.
ASSEMBLY STEP 2
Fasten the Rail to the Motor Unit
1. Insert a 1/4"-20x1-3/4" bolt into the cover protection
bolt hole on the back end of the rail as shown. Tighten
securely with a 1/4"-20 lock nut. DO NOT overtighten.
2. Remove the two bolts from the top of the motor unit.
3. Use the carton to support the front end of the rail.
4. Place the “U” bracket, fl at side down onto the motor
unit and align the bracket holes with the bolt holes.
Fasten the “U” bracket with the previously removed
bolts; DO NOT use any power tools. The use of power
tools may permanently damage the garage door
opener.
5. Attach spreader to the motor unit with two screws.
ASSEMBLY STEP 3
Install the Idler Pulley
1. Lay the chain/cable beside the rail, as shown. Grasp
the end of the cable and pass approximately 12"
(30 cm) of cable through the window. Allow it to hang
until Assembly Step 4.
2. Remove the tape from the idler pulley. The inside
center should be pre-greased. If dry, regrease to
ensure proper operation.
3. Place the idler pulley into the window as shown.
4. Insert the idler bolt from the top through the rail
and pulley. Tighten with a 3/8" lock washer and
nut underneath the rail until the lock washer is
compressed.
5. Rotate the pulley to be sure it spins freely.
6. Locate the rail tab. The rail tab is between the idler bolt
and the trolley in the front rail section. Use a fl at head
screwdriver and lift the rail tab until the tab is vertical
(90°).
HARDWARE SHOWN ACTUAL SIZE
Lock Nut
1/4"-20
Bolt 1/4"-20x1-3/4"
Hex Screws
8-32x7/16"
Bolts
Lock Nut
Cover
Protection
Bolt Hole
Chain Spreader
“U”
Bracket
Bolt
1/4"-20x1-3/4"
Lock
Washer
3/8"
Nut 3/8"
Cable Link
Idler
Bolt
Trolley
Idler
Pulley
Grease
Inside Pulley
Screwdriver
Chain
and Cable
Rail
Tab
CORRECT
INCORRECT
Rail Tab
HARDWARE SHOWN ACTUAL SIZE
Lock Washer 3/8"
Nut 3/8" Idler Bolt