The Belimo LMCB24-3 is a compact non-spring-return damper actuator delivering 45 in-lb [5 Nm] of torque with on/off and floating-point control on AC/DC 24 V power. It direct-couples to round or square damper shafts from 1/4 in. to 5/8 in. (up to 3/4 in. with an accessory clamp) 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 LMB platform for small to mid-size commercial HVAC dampers. It runs 90° of travel in a fast 35 seconds.
Specifications sourced from the official Belimo LMCB24-3 technical data sheet (rev 2025-10-06).
Overview
Belimo LM-Series actuators are compact non-spring-return drives for small and mid-size 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 LMCB24-3 produces 45 in-lb [5 Nm] and mounts directly to round or square damper shafts from 1/4 in. to 5/8 in. (up to 3/4 in. with an accessory clamp). It completes 90° of travel in a fast 35 seconds. Two-position on/off and 3-wire floating-point control position the damper from a controller or switch.
Best for
- Compact non-spring-return damper control where fail-safe return is not required
- Small to mid-size damper and louver positioning (45 in-lb)
- Direct shaft mount, 1/4-5/8 in. (to 3/4 in. with accessory clamp)
- Faster actuation (35-second run time)
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.
45 in-lb Torque
Sized for small and mid-size dampers; direct-couples to round or square damper shafts from 1/4 in. to 5/8 in. (up to 3/4 in. with an accessory clamp).
On/Off & Floating Point
Accepts two-position on/off or 3-wire floating-point control from a controller, relay or switch.
Fast 35-Second Run Time
Drives 90° of travel in about 35 seconds — faster actuation without a spring return.
cULus Listed & Quiet
Double-insulated (Class 2), cULus listed, ISO 9001 built, UL 2043 plenum-rated for long, maintenance-free service.
Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | Belimo |
| Part Number | LMCB24-3 |
| Actuator Type | Non-Spring-Return (Non Fail-Safe) Damper Actuator |
| Nominal Voltage | AC/DC 24 V |
| Nominal Frequency | 50/60 Hz |
| Power Consumption (Running) | 1.5 W |
| Transformer Sizing | 3 VA |
| Torque | 45 in-lb [5 Nm] |
| Control Signal | On/Off and Floating Point (3-wire) |
| Shaft Range | 1/4 in. to 5/8 in. (to 3/4 in. with accessory clamp) |
| Angle of Rotation | Max. 95° (adjustable mechanical stop) |
| Running Time (Motor) | 35 s / 90° Running time motor note constant, independent of load Noise level, motor 45 dB |
| Behavior on Power Loss | Holds last position (non-spring-return) |
| Manual Override | External push button (self-locking gear) |
| Direction of Motion | Selectable with 0/1 switch |
| 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 | 0.73 lb [0.33 kg] |
| Warranty | 5 Years |
Documentation
Related Products
Accessories & Mounting
Common Belimo accessories for mounting, linkage, signaling and powering the LMCB24-3, drawn from the actuator datasheet. All are stocked by ZOT Supply as an authorized Belimo distributor.
Mounting & Linkage
Electrical Add-Ons
Enclosures & Weather Shields
Frequently Asked Questions
What is the Belimo LMCB24-3?
The Belimo LMCB24-3 is a compact non-spring-return (non-fail-safe) damper actuator for commercial HVAC. It produces 45 in-lb [5 Nm] of torque, uses on/off and floating-point control on AC/DC 24 V power, and holds its last position on loss of power. Its housing is rated NEMA 2.
Is the LMCB24-3 a spring-return (fail-safe) actuator?
No. The LMCB24-3 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 fail-safe operation, choose a spring-return Belimo LF-Series actuator instead.
What happens to the LMCB24-3 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.
What shaft sizes does the LMCB24-3 fit?
It direct-couples to round or square damper shafts from 1/4 in. to 5/8 in. (up to 3/4 in. with an accessory clamp) using its universal clamp.
What control signal does the LMCB24-3 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 LMCB24-3?
Motor running time is about 35 s / 90° Running time motor note constant, independent of load Noise level, motor 45 dB for 90 degrees of travel. That faster run time suits applications needing quicker damper response.
Is the Belimo LMCB24-3 available from an authorized Belimo distributor?
Yes. ZOT Supply is an authorized Belimo distributor and carries the LMCB24-3. Every unit ships factory new with Belimo's full 5-year warranty and application support.
- Actuator Type:
- Non-Spring-Return
- Torque:
- 45 in-lb
- Control Signal:
- On/Off
- Voltage:
- 24 VAC/DC
- Auxiliary Switch:
- No
- Series:
- LMB
