LiftMaster BG770 Industrial-Duty Single Arm Barrier Gate Operator - Manual (Page 9)

9
I N S T A L L A T I O N
MODEL BG790: WISHBONE COUNTERWEIGHTED ARM
1. Bolt counterweights to ends of arms clamps (Figure 7). Use
caution lifting 57 lb. weights.
2. Bend and fasten the two arms together (Figure 8). If an
extension arm is required, sandwich the extension arm
between the two halves of the wishbone arm before bolting
together. Refer to Arm Fabrication on page 6 for extension
arm preparation.
3. Assemble the two 3/8" threaded rods to the arms for center
support.
4. Be prepared for gate to start when you turn the power on. Turn
on power and test the gate.
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.
WARNING
Figure 8
Figure 7
(2) 1/2"-13 Hex Nuts
(4) 1/2" Lock Washers
(4) 1/2"-13 x 2-1/4"
Bolts
(8) 1/2"-13 Hex Nuts
(8) 1/2" Lock Washers
Wishbone Arm Arc of Travel
Ensure adequate clearance for travel of arm.
(2) 1/2"-13 Hex Nuts
(2) 1/2" Lock Washers
(2) 1/2" Flat Washers
(8) 1/2"-13 x 2-1/4"
Hex Bolts
(2) 1/2"-13 x 3" Bolts
(2) 1/2" Flat Washers
3/8"-16 Nut
3/8" Flat Washer
(2) 3/8"-16 x 18"
Threaded Rods
(8) 3/8"-16 Nuts
(4) 3/8" Lock Washers
(8) 3/8" Flat Washers
(4) 1/2" Flat Washers
Counterweight
See Detail A
30" Radius
18-5/8"
Arm Clamp
Wishbone Arm
Extension Arm