Tighten The Belt And Install The Sprocket Cover - Chamberlain HD920EV Manual

Assembly

5 Tighten the belt and install the sprocket cover

To avoid possible SERIOUS NJURY to finger from moving garage door opener:
• ALWAYS keep hand clear of sprocket while operating opener.
• Securely attach sprocket cover BEFORE operating.
H8
Spring Trolley Nut
5.3
Tighten the spring trolley nut with an adjustable wrench or a 7/16" open end wrench about a quarter turn until the spring releases and snaps the
nut ring against the trolley. This sets the spring to optimum belt tension.
HARDWARE
H9 (3)
Hex Screw #8x3/8"
(Packed with the
sprocket cover)
5.1
By hand, thread the spring trolley nut on the
threaded shaft (H8) until it is finger tight
against the trolley. Do not use any tools.
Remove the screwdriver.
(to motor unit)
Nut Ring
Nut Ring
AFTER
BEFORE
1" 1-1/4"
(2.5 cm) (3.18 cm)
10
5.2
Insert a flathead screwdriver tip into one
of the nut ring slots and brace it firmly
against the trolley.
Nut ring slot
H8
5.4
Position the sprocket cover over the garage
door opener sprocket and attach with hex
screws (H9).
H9