User Guide
10 © Copyright 2008 TAC All Rights Reserved. F-26645-7
Canadian Department of Communications (DOC)
Note:
This Class B digital apparatus meets all requirements of the Canadian Interference-
Causing Equipment Regulations.
Cet appareil numerique de la classe B respecte toutes les exigences du Reglement sur le 
material broilleur du Canada.
European Standard EN 55022
Warning:
This is a Class B digital (European Classification) product. In a domestic 
environment this product may cause radio interference in which case the user may be 
required to take adequate measures.
Location
Caution:
Avoid locations where excessive moisture, corrosive fumes, vibration, or 
explosive vapors are present.
Mounting
Caution:
To remain in NEMA 2/IP54 compliance, the MS4X-715X and MS4X-707X series 
actuators should be mounted with conduit end down.
Mount the TAC DuraDrive Actuator directly on the damper shaft in locations that clear the 
maximum dimensions of the actuator case and allow the actuator to be mounted flush to the 
surface of the terminal box and perpendicular to the damper shaft.
MX41-707X and MX41-715X If the universal clamp is not set to 0° on the position indicator, 
manually wind the actuator in the direction indicated with hex wrench from -5° to 0° and lock 
with a screwdriver.
Note:
Some terminal boxes have sheet metal screw heads or other protrusions near the 
damper shaft. In these cases, a spacer or shim may be added under the anti-rotation 
bracket of the actuator to make the actuator perpendicular to the shaft.
Damper Actuator Sizing
Correct sizing of the actuator is necessary for proper control of dampers. The area of 
damper that can be controlled by a given actuator is dependent upon the type of damper, 
the quality of the damper, the pressure drop across the damper in the closed position, and 
the velocity of the air flow through the damper. To obtain actual damper torque 
requirements, contact the damper manufacturer.
Damper Shaft Sizing 
Use the “Long Damper Shaft” mounting instructions if the damper shaft is at least 3-1/2" 
(90 mm) long. 
Use the “Short Damper Shaft” mounting instructions if the damper shaft is shorter than 
3-1/2" (90 mm) or the area around the damper shaft is too narrow to allow standard 
mounting, as described in the “Short Damper Shaft” mounting section. 
Changing Direction of Rotation
The MS40-7043, MS4X-7074, and MS4X-7153 actuators are equipped with a switch to 
control the direction of rotation. The switch can be set to "L” (left) or “R” (right) rotation. An 
actuator set to “L” will have a clockwise rotation when viewed from the left side. When 
viewed from the right side the rotation will be counterclockwise. Refer to Figure-3.
Caution:
These are spring return actuators. It is possible to switch to a direction that 
moves the actuator against the -5° positive stop. Example: Viewing the actuator from the 
left side with the switch set to “R” and an increasing signal. The actuator will attempt to 
rotate beyond the -5° stop and will stall.










