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Install the belt and attach the belt capretainer, Assembly step 4, Install the belt and attach the belt cap retainer – Chamberlain WHISPER DRIVE 248754 User Manual

Page 10

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ASSEMBLY STEP 4

Install the Belt and Attach the Belt Cap
Retainer

1. Pull the belt around the idler pulley and toward the

trolley. The ribbed side must contact the pulley.

2. Hook the trolley connector into the retaining slot on the

trolley as shown.

3. With the trolley against the screwdriver, dispense the

remainder of the belt along the rail length toward the
motor unit and around the belt pulley. The belt pulley
teeth must engage the belt.

4. Check to make sure the belt is not twisted. Connect

the trolley threaded shaft with the master link, as
illustrated:

• Push pins of master link bar through holes in end of

belt and trolley threaded shaft.

• Push master link cap over pins and past pin notches.

• Slide clip-on spring over cap and onto pin notches

until both pins are securely locked in place.

5. Insert the trolley threaded shaft through the hole in the

trolley. Be sure the belt is not twisted.

6. Hold the belt at the trolley shaft as you thread the

spring nut by hand onto the shaft until fi nger tight
against the trolley. DO NOT use any tools.

7. Remove the screwdriver.

8. Position the belt cap retainer over the motor unit belt

pulley as shown and fasten to the mounting plate with
8x3/8" hex screws provided.

To avoid possible SERIOUS INJURY to fi ngers from
moving garage door opener:
• ALWAYS keep hand clear of belt pulley while

operating opener.

• Securely attach belt pulley cover BEFORE operating.

HARDWARE SHOWN ACTUAL SIZE

Spring/Trolley Nut (1)

Hex Screw 8x3/8"

Motor Unit
Belt Pulley

Belt Cap
Retainer

Mounting
Plate

8x3/8" Hex Screws

Spring Nut

Master Link
Clip-On Spring

Master Link Cap

Master
Link Bar

Pin
Notch

Trolley
Threaded
Shaft

Hole

Retaining
Slot

Trolley
Connector

Idler
Pulley