Control Arm Assembly - Chamberlain LiftMaster Professional SW420 Installation And Maintenance Instructions Manual

Control Arm Assembly

1 Assemble the control arm to the operator hub.
2 Push up the manual release pin (80-2752) from below the
hub and through the control arm. Then retain in place
with the clevis pin (80-2753).
3 Using the 3/8" washers (80-206-65), take up any play
between the clevis pin and the top of the control arm.
4 When the manual release pin is allowed to drop down, the
control arm should swivel freely about the hub. Leave the
arm free to pivot at this time.
5 Fasten the arm stop (07-2705) to the extension arm. Left
hand or right hand installations call for mounting the arm
stop on opposite sides of the extension arm.
CAUTION
If the arm stop is installed incorrectly, the gate will
be prevented from opening and damage to the
operator may result!
6 Assemble the extension arm to the control arm using the
hardware provided as shown in Figure
7 Assemble the gate bracket (10-2111) to the extension
arm as shown.
8 Put the gate in the fully closed position and extend the
arm assembly out to the closed gate. Mark the point on
the gate where the gate bracket will mount to the gate.
IMPORTANT NOTE: The gate bracket must be
installed so that the arm assembly is level and able
to operate smoothly.
9 The gate bracket must be installed on a structural
member of the gate. If required, install a horizontal
support on the gate at the appropriate height.
10 Attach the gate bracket with U-bolts or by welding.
9.
Installation
See Figure 9.
A cotter pin (86-HP-4) keeps the
clevis pin (80-2753) from
vibrating out of place.
Refer to Figure 9 to determine
which way to mount the arm stop.
Use the center hole in the
extension arm. The other holes
may be used for arm adjustment
at a later time.
The gate bracket should pivot
freely on the arm.
Be sure that the control arm is
pressed tightly against the arm
stop.
Doc 01-G0610
15
Rev A