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Install the belt and attach the belt cap retainer, Assembly step 4 – Craftsman 139.53915D User Manual

Page 10

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10

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.

Hex Screw 8x3/8"

HARDWARE SHOWN ACTUAL SIZE

Spring/Trolley Nut

Spring Nut

Belt Cap
Retainer

Mounting
Plate

Motor Unit
Sprocket

Hex Screws
#8x3/8"

Trolley
Connector

Idler Pulley

Retaining
Slot

Hole

Master Link
Clip-On Spring

Master Link Cap

Trolley
Threaded
Shaft

Master
Link Bar

Pin
Notch

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.