Install the belt and attach the belt cap retainer, Warning caution warning warning, Assembly step 4 – Chamberlain WHISPER DRIVE 248739 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 sprocket. The sprocket teeth
must engage the belt.

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

FLAT side of the trolley threaded shaft is facing the rail.
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 and the FLAT
side of the trolley threaded shaft faces the rail.

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

spring nut by hand onto the shaft until finger tight
against the trolley. Do not use any tools.

7. Remove the screwdriver.

8. Position the belt cap retainer over the motor unit

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

To avoid possible SERIOUS INJURY to fingers from moving
garage door opener:
• ALWAYS keep hand clear of sprocket while operating opener.
• Securely attach sprocket cover BEFORE operating.

WARNING

CAUTION

WARNING

Trolley
Connector

Idler Pulley

Retaining
Slot

Round
Hole

Master Link
Clip-On Spring

Master Link Cap

Trolley
Threaded
Shaft

Master
Link Bar

Pin
Notch

Hex Screw 8x3/8"

HARDWARE SHOWN ACTUAL SIZE

Spring/Trolley Nut

Spring Nut

Motor Unit
Sprocket

Mounting
Plate

Hex Screws
#8x3/8"

Belt Cap
Retainer