The Afb And Afx Series Actuators Provide True Spring Return Operation For Reliable Failsafe Application And Positive Close-Off On Air Tight Dampers. The Spring Return System Provides Constant Torque To The Damper With, And Without, Power Applied To The Actuator. The Afb And Afx Series Provides 95° Of Rotation And Is Provided With A Graduated Position Indicator Showing 0° To 95°. The Afb24-Sr And Afx24-Sr Uses A Brushless Dc Motor Which Is Controlled By An Application Specific Integrated Circuit (Asic) And A Microprocessor. The Microprocessor Provides The Intelligence To The Asic To Provide A Constant Rotation Rate And To Know The Actuator's Exact Fail-Safe Position. The Asic Monitors And Controls The Brushless Dc Motor's Rotation And Provides A Digital Rotation Sensing Function To Prevent Damage To The Actuator In A Stall Condition. The Actuator May Be Stalled Anywhere In Its Normal Rotation Without The Need Of Mechanical End Switches. The Afb24-Sr-S And Afx24-Sr-S Versions Are Provided With Two Built-In Auxiliary Switches. These Spdt Switches Provide Safety Interfacing Or Signaling, For Example, For Fan Start-Up. The Switching Function At The Fail-Safe Position Is Fixed At +10°, The Other Switch Function Is Adjustable Between +10° To +90°. The Afb24-Sr, Afb24-Sr-S, Afx24-Sr And Afx24-Sr-S Actuator Is Shipped At +5° (5° From Full Fail-Safe) To Provide Automatic Compression Against Damper Gaskets For Tight Shut-Off. Made in United States. Manufactured by Belimo Air Controls.