Arm Attachment - Chamberlain LiftMaster Professional BG770 Owner's Manual

ARM ATTACHMENT

For easier access during installation, the top cover of the unit may
be opened by removing the two wing nuts from underneath,
inside the cabinet.
MODEL BG770: STANDARD ARM
Attach arm to the arm hub flange (Figure 5).
MODEL BG770: OPTIONAL ARM
Attach arm to the arm hub flange (Figure 6).
Figure 6
(4) Hex Bolts
Extension Arm
S Screw
I N S T A L L A T I O N
See Detail A
Lift Arm
WARNING
When following the procedure below, the motor belt will turn
and the drive shaft will move during some of the steps. Keep
hands and tools out of the gate cabinet and away from the
belt and drive shaft or SERIOUS INJURY may result. Be sure
to DISCONNECT power while installing the arm attachment.
Figure 5
Gate Arm
Hex Bolt
1/2"-13 x 2-1/4"
Lock Washer and
1/2"-13 Hex Nut
Hex Bolt
(2) Flat Washers
DETAIL A
See Detail B
Threaded Rod
Hex Bolt
Flat Washer
DETAIL B
8
Hub Flange
(2) Flat Washers
Hex Nut
Hex Nut
Hex Nut
Flat Washer
Threaded Spacer
Flat Washer
Flat Washer
Hex Bolt