The Belimo AMB120-3 is a non-spring-return damper actuator delivering 180 in-lb [20 Nm] of torque with on/off and floating-point control on AC 100-240 V power. It direct-couples to damper shafts up to 1.05 in. diameter and holds its last position on loss of power (it is non-fail-safe, with no spring return), making it a proven member of the AMB platform for commercial HVAC damper control where fail-safe operation is not required.
Specifications sourced from the official Belimo AMB120-3 technical data sheet (rev 2025-12-24).
Overview
Belimo AM-Series actuators are non-spring-return drives for commercial HVAC dampers — they position the damper under power and hold the last commanded position when power is removed (there is no spring-return fail-safe). The AMB120-3 produces 180 in-lb [20 Nm] of torque and mounts directly to the damper shaft. Two-position on/off and 3-wire floating-point control position the damper from a controller or switch.
Best for
- Commercial HVAC damper control where fail-safe return is not required
- Non-spring-return damper and louver positioning (180 in-lb)
- Direct shaft mount up to 1.05 in. diameter
- Line-voltage systems (AC 100-240 V)
Key Features
Non-Spring-Return Design
Holds the last commanded position when power is removed (non-fail-safe). Lower cost and power draw than a spring-return actuator where fail-safe operation is not required.
180 in-lb Torque
Direct-couples to damper shafts up to 1.05 in. diameter and sizes a wide range of commercial dampers and louvers.
On/Off & Floating Point
Accepts two-position on/off or 3-wire floating-point control from a controller, relay or switch.
Line-Voltage Power
Runs directly on AC 100-240 V line power — no separate 24 V transformer required.
cULus Listed & Quiet
Double-insulated (Class 2), cULus listed, ISO 9001 built, and UL 2043 plenum-rated for long, maintenance-free service.
Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | Belimo |
| Part Number | AMB120-3 |
| Actuator Type | Non-Spring-Return (Non Fail-Safe) Damper Actuator |
| Nominal Voltage | AC 100-240 V |
| Nominal Frequency | 50/60 Hz |
| Power Consumption (Running) | 2.5 W |
| Transformer Sizing | 5.5 VA |
| Torque | 180 in-lb [20 Nm] |
| Control Signal | On/Off and Floating Point (3-wire) |
| Angle of Rotation | Max. 95° (adjustable mechanical stop) |
| Running Time (Motor) | 95 s / 90° Running time motor note constant, independent of load |
| Behavior on Power Loss | Holds last position (non-spring-return) |
| Manual Override | Self-locking; declutch / hand crank per model |
| Direction of Motion | Selectable (CW/CCW) |
| Electrical Connection | 18 AWG plenum cable, 3 ft [1 m], 1/2" NPT conduit connector |
| Overload Protection | Electronic, full 0-95° rotation |
| Electrical Protection | Double insulated (Class 2) |
| Enclosure Rating | NEMA 2 / UL Type 2 |
| Ambient Temperature | -22 to 122°F [-30 to 50°C] |
| Agency Listing | cULus (UL60730-1A / -2-14, CAN/CSA) |
| Quality Standard | ISO 9001 |
| Plenum Rated | UL 2043 (suitable for air plenums) |
| Weight | 2.5 lb [1.2 kg] |
| Warranty | 5 Years |
Documentation
Related Products
Accessories & Mounting
Common Belimo accessories for mounting, signaling and protecting the AMB120-3, drawn from the actuator datasheet. All are stocked by ZOT Supply as an authorized Belimo distributor.
Mounting & Shaft
Electrical Add-Ons
Enclosures & Weather Shields
Frequently Asked Questions
What is the Belimo AMB120-3?
The Belimo AMB120-3 is a non-spring-return (non-fail-safe) damper actuator for commercial HVAC. It produces 180 in-lb [20 Nm] of torque, uses on/off and floating-point control on AC 100-240 V power, and holds its last position on loss of power. Its housing is rated NEMA 2.
Is the AMB120-3 a spring-return (fail-safe) actuator?
No. The AMB120-3 is non-spring-return: when power is lost it holds its last commanded position rather than driving to a fail-safe position. If you need the damper to fail to a known open or closed position on power loss, choose a spring-return Belimo AF/AM-Series actuator instead.
What happens to the AMB120-3 when power is lost?
It stays put. A non-spring-return actuator maintains its last position when power is removed and resumes from there when power returns — there is no spring to drive it to a fail-safe position.
What torque does the AMB120-3 provide and what shaft sizes does it fit?
It delivers 180 in-lb [20 Nm] and direct-couples to round or square damper shafts up to 1.05 in. diameter using its universal clamp.
What control signal does the AMB120-3 use?
It uses on/off and floating-point control. On/Off and 3-wire floating-point control are driven from a controller, relay or switch.
What is the running time of the AMB120-3?
Motor running time is about 95 s / 90° Running time motor note constant, independent of load for 90 degrees of travel.
What voltage does the AMB120-3 run on?
The AMB120-3 is a line-voltage actuator: it runs on AC 100-240 V, so no separate 24 V control transformer is required.
Is the Belimo AMB120-3 available from an authorized Belimo distributor?
Yes. ZOT Supply is an authorized Belimo distributor and carries the AMB120-3. Every unit ships factory new with Belimo's full 5-year warranty and application support from our team.
- Actuator Type:
- Non-Spring-Return
- Torque:
- 180 in-lb
- Control Signal:
- On/Off
- Voltage:
- Line Voltage (100-240 VAC)
- Auxiliary Switch:
- No
- NEMA 4X Enclosure:
- No
- Series:
- AMB
