Pressure Type Slipping Clutch; Solenoid Actuated Brake - Chamberlain LiftMaster Professional SL540 Manual

The clutch is shipped from left the factory completely loosened.
In this position, it will not allow the operator to move the gate, so
it must be adjusted. Due to the internal speed sensor, you may
get obstruction sensing reaction during the clutch adjustment
procedure. You must adjust the clutch so that it produces just
enough force to move the gate, but yet will easily slip when the
gate meets with an obstruction.
ADJUSTING
Adjust the clutch nut gradually until there is just enough tension
to permit the operator to move the gate smoothly through a
complete open/close cycle, but to allow the clutch to slip if the
gate is obstructed.
The brake minimizes over-travel caused by gate coasting. An
added feature of the brake is to assist in preventing backdriving
of the gate. The brake is spring-applied whenever the motor is
not running. Anytime the motor is running, the electric solenoid
physically releases the brake.
ADJUSTING
1. Tighten lock nut on brake lever until brake lever is horizontal.
2. Loosen lock nut until brake lever drops 1/8" to 3/8".
3. Operate gate briefly and check lever position. If the 1/8" to 3/8"
dimension is not maintained in the power off position, tighten
or loosen the lock nut as required.
P R E S S U R E T Y P E S L I P P I N G C L U T C H
Clutch
Adjustment
Lock Nut
S O L E N O I D A C T U A T E D B R A K E
WARNING
To avoid SERIOUS PERSONAL INJURY or DEATH
DISCONNECT electric power BEFORE adjusting clutch.
CAUTION
WARNING
This friction clutch system is NOT an automatic reversing
device. It only serves to minimize damage to the gate operator
CAUTION
and gate, and to HELP minimize vehicle damage. If you need
an external automatic obstruction sensing device, items such
as gate edges and photo beams are available to help protect
pedestrians.
WARNING
To avoid SERIOUS PERSONAL INJURY or DEATH
DISCONNECT electric power BEFORE adjusting clutch.
CAUTION
Lock Nut
24
Brake lever should be
close to horizontal when
motor is running
1/8" to 3/8"
Brake lever should be
as shown here when motor
is not running