Fasten The Rail To The Motor Unit; Install The Idler Pulley - Chamberlain POWER DRIVE 248735S 3/4 HP Owner's Manual

ASSEMBLY STEP 2

Fasten the Rail to the Motor Unit

• Insert a 1/4"-20x2" bolt, washer and spacer 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 bolt and lock nut from the top of the
motor unit.
• Attach spreader to the motor unit with two screws.
• Place the "U" bracket, fl at side down onto the bolt
mounted on the motor unit and align the bracket hole
with the bolt holes. Fasten with the previously removed
bolt and lock nut.
• 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.
HARDWARE SHOWN ACTUAL SIZE
Washer 5/8"
Bolt 1/4"-20x2"
ASSEMBLY STEP 3

Install the Idler Pulley

• Lay the chain/cable beside the rail, as shown. Grasp
the end with the cable loop 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.
HARDWARE SHOWN ACTUAL SIZE
Lock Washer 3/8"
Lock Nut
1/4"-20
Spacer
Lock Nut 1/4"-20
To avoid SERIOUS damage to garage door opener,
use ONLY those bolts/fasteners mounted in the top of
the opener.
Bolt
Washer
Spacer
Cover
Protection
Bolt Hole
Lock Nut
Chain and Cable
Screwdriver
Idler
Bolt
Lock
Washer
3/8"
Nut 3/8"
9
Hex Screws
8-32x7/16"
Bolt
Lock Nut
"U" Bracket
SLIDE RAIL TO
STOPS ON TOP AND
SIDES OF BRACKET
Bolt
Pulley
Washer
Trolley
Trolley
Stop Hole Bolt
Grease
Inside Pulley
Idler
Pulley
Nut
3/8"
Cable Link
Bolt 1/4"-20x1-3/4"
Idler Bolt
Chain Spreader
Motor Unit
Sprocket
Rail
Nut
Idler
Lock
Pulley
Nut