Step 2 fasten the rail to the motor unit, Step 3 install the idler pulley, Assembly step 2 – Chamberlain CG40D 1/2 HP User Manual
Page 9: Assembly step 3, Fasten the rail to the motor unit, Install the idler pulley
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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
• 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.
• Remove the two bolts from the top of the motor unit.
• Place the “U” bracket, flat side down onto the motor unit
and align the bracket hole with the bolt holes. Fasten
with the previously removed bolts.
• Align the rail assembly with the top of the motor unit.
Slide the rail end onto the “U” bracket, all the way to the
stops that protrude on the top and sides of the bracket.
• Attach spreader to the motor unit with two screws.
ASSEMBLY STEP 3
Install the Idler Pulley
• 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 5.
• Remove the tape from the idler pulley. The inside center
should be pre-greased. If dry, regrease to ensure proper
operation.
• Place the idler pulley into the window as shown.
• 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.
• Rotate the pulley to be sure it spins freely.
• Insert a 1/4"-20x1-3/4 bolt into the trolley stop hole in
the front of the rail as shown. Tighten securely with a
1/4"-20 lock nut.
Bolts
Hex Screws
8-32x7/16"
Chain
Spreader
Motor Unit
Sprocket
"U" Bracket
Lock Nut
SLIDE RAIL TO STOPS
ON TOP AND SIDES
OF BRACKET
Cover
Protection
Bolt Hole
Bolt
Lock
Washer
3/8"
Nut 3/8"
Cable Link
Idler
Bolt
Chain and
Cable
Pulley
Rail
Bolt
Nut
Washer
Trolley
Idler
Pulley
Idler
Pulley
Grease
Inside Pulley
Screwdriver
Trolley
Stop Hole
Bolt
Lock
Nut
Lock Nut
1/4"-20
Bolt 1/4"-20x1-3/4"
HARDWARE SHOWN ACTUAL SIZE
Nut 3/8"
Lock Washer 3/8"
Idler Bolt
Lock Nut 1/4"-20
Bolt 1/4"-20x1-3/4"
HARDWARE SHOWN ACTUAL SIZE