Chamberlain HD520EV User Manual page 9

Assembly
STEP 4 Install the belt
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 (Figure 1).
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 (Figure 2). The sprocket teeth must engage
the belt.
4. Check to make sure the belt is not twisted. Connect the trolley threaded shaft with the master link
(Figure 3).
Push pins of master link bar through holes in end of belt and trolley threaded shaft.
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Push master link cap over pins and past pin notches.
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Slide clip-on spring over cap and onto pin notches until both pins are securely locked in
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place.
5. Remove the spring trolley nut from the threaded shaft.
6. Insert the trolley threaded shaft through the hole in the trolley.
Threaded Shaft with Spring Trolley Nut
Master
Link
HARDWARE
Figure 1
Trolley Connector
Retaining
Slot
Figure 3
Front Rail
Section
(TO DOOR)
8
Figure 2
Sprocket
Master
Link
Idler
Pulley
Threaded Shaft