Product Overview

bracket has two (2) locator holes (dimension E in Figure-3) for

3" (76 mm) stroke actuators and two (2) locator notches

(dimension F in Figure-3) for 4" (102 mm) stroke actuators;

the choice of a locator being based on whether clockwise or

counterclockwise rotation is required as the piston shaft is

extended by increasing signal pressure.

The pre-assembled crank arm is then slipped over the damper

shaft extension and, when properly positioned, the bracket is

secured to the duct surface by driving sheet metal screws

through its mounting holes, using care not to obstruct

movement of the damper blades. If the duct is to be insulated,

suitable standoff posts and bolts should be substituted for the

sheet metal screws.

Note:

3" stroke actuators use the middle pivot hole of the

crank arm; 4" stroke actuators use the outermost pivot hole.

The final installation step of locking the crank arm to the

damper shaft extension should be done when control air is

available or by means of a squeeze bulb:

a. For a normally closed damper, apply air pressure to

the actuator equal to the low end of its spring range,

e.g.: 5 psig (34 kPa) for a 5 to 10 psig (34 to 69 kPa)

spring, then close the damper blades against their

stops; a slot in the end of the extension shaft

indicates blade position. After assuring that it is

parallel to the duct surface, clamp the crank arm to

the extension shaft by tightening the two (2) hexhead

screws. When air pressure is removed from the

actuator, its residual low end spring force will provide

additional damper close-off pressure.

b. For a normally open damper, apply air pressure to the

actuator equal to the high end of its spring range, e.g.:

10 psig (69 kPa) for a 5 to 10 psig (34 to 69 kPa)

spring, then close the damper blades against their

stops. Secure the crank arm to the drive shaft as

described above. Signal pressure above the spring

range will then provide additional close-off force.

Note:

The standard actuator hardware will rotate a damper

90° for full actuator stroke.

Figure-3 M573 and M574 Right Angle Mounting Dimensions for External Applications.