Rotary Actuators
A rotary actuator converts energy into controlled rotational motion over a fixed angle. Most are designed for 90 degrees. When the application calls it, the actuator moves to position and holds there.
They show up wherever repeatable angular movement matters: quarter-turn valve control, flow regulation, damper positioning. Industrial systems, mobile equipment, engine-mounted applications. If something needs to rotate to a known position and stay there, a rotary actuator is doing the work.
This page covers electric rotary actuators built for environments where vibration, temperature swings, and continuous operation are the norm, not the exception.
Electric Rotary Actuator Capabilities
The electric rotary actuators described here fall within the following technical range:
- Torque range: 25 Nm or 125 Nm
- Rotation: 90-degree quarter turn
- Power supply: 24 VDC
- Duty cycle: 100 percent at rated load
- Control options: 0–10 V, 4–20 mA, PWM, SAE J1939 CAN
- Environmental protection: IP67 and IP69K
- Service life: Tested to 1,000,000 cycles at rated load
- Designed for high vibration and mechanical shock environments
This snapshot allows you to quickly determine whether these actuators are relevant to your application before diving into details.
What Is a Rotary Actuator
A rotary actuator produces rotation over a defined range. It is not a motor. It does not spin continuously. Travel limits are set mechanically or electronically depending on actuator type, making positioning repeatable and torque output consistent.
You select one when the application requires controlled angular movement to a known position, whether that is opening a valve, positioning a damper, or moving a mechanism without overshoot.
Types of Rotary Actuators
Rotary actuators come in three main types: electric, pneumatic, and hydraulic. AMOT only manufactures electric rotary actuators. The information below explains how the types differ, so you can confirm that an electric actuator fits your application.
Electric Rotary Actuators
- Powered by electricity, commonly 24 VDC in mobile and engine-mounted systems
- Provide precise positioning and repeatable control
- Easily integrated with electronic control systems and sensors
Pneumatic Rotary Actuators
- Powered by compressed air
- Fast response but limited positioning accuracy
- Typically used in fixed industrial environments with available air supply
Hydraulic Rotary Actuators
- Powered by hydraulic pressure
- Capable of very high torque output
- Used where hydraulic systems already exist, such as heavy machinery
Electric Rotary Actuators for Harsh and Mobile Environments
Most actuators were designed for controlled environments and adapted from there. Factory floors. Climate-managed cabinets. Applications where the hardest thing the actuator faces is being turned on and off.
That is not where these actuators live.
On-engine applications run continuous vibration across a broad frequency range. Mining equipment takes mechanical shock that standard mounts do not survive. Marine and oil and gas environments combine moisture exposure, washdown, and temperature cycling that will find every weakness in a sealed enclosure. Locomotives run cold starts and heat buildup in the same shift. These conditions do not give an actuator time to recover between cycles.
Electric actuators used here need to be designed for it from the start, not rated for it after the fact. That means documented vibration and shock performance, sealed enclosures rated for submersion and high-pressure washdown, wide temperature ratings that hold at both ends, and 100 percent duty cycle at maximum load and maximum temperature. Not under ideal conditions. Under the conditions the application actually runs in.
How to Select a Rotary Actuator
When selecting a rotary actuator, the following factors should be evaluated:
- Required output torque for the load being moved
- Required rotation angle, commonly 90 degrees for quarter-turn applications
- Control and feedback signals needed by the control system
- Available power supply, such as 24 VDC
- Ambient temperature range during operation
- Expected vibration and shock levels
- Duty cycle and expected service life
- Mounting pattern and allowable orientations
- Environmental sealing requirements such as IP ratings
- Body and housing materials, particularly in corrosive, marine, or washdown environments
Common Rotary Actuator Applications
Rotary actuators are commonly used in:
- Quarter-turn industrial valves for flow control
- On-engine valve and air management systems
- Locomotives and rail equipment
- Oil and gas equipment
- Process control systems
- Marine and naval vessels
- Hydrogen fuel cell systems
These applications often combine the need for precise control with harsh operating conditions.
AMOT Electric Rotary Actuator Series Overview
AMOT was sourcing actuators off the shelf for its own valve products and kept running into the same problem: nothing on the market was built to survive the environments its customers actually operate in. So AMOT built one from the ground up.
Both series that came out of that work run on 24 VDC, deliver 90-degree quarter-turn motion, support analog and digital control, and are rated for continuous duty in demanding conditions. The design intent is the same across the family. The only question that determines which unit fits is torque.
| Feature | EHC Series | EH Series |
|---|---|---|
| Torque | 25 Nm | 125 Nm |
| Operating temperature | -40°C to +125°C | -40°C to +100°C |
| Quarter-turn time | 4 seconds | 6 seconds |
| Duty cycle | 100 percent | 100 percent |
| Ingress protection | IP67, IP69K | IP67, IP69K |
| Mass | 4 kg | 11 kg |
| Mounting | ISO 5211 F07 | ISO 5211 F07 and F10 |
| Control options | 0–10 V, 4–20 mA, PWM, J1939 CAN | 0–10 V, 4–20 mA, PWM, J1939 CAN |
Both series carry the same environmental ratings, the same duty cycle, and the same design origin. One sizing question determines the right unit: how much torque does the application require? If the answer is 25 Nm, that is the EHC Series. If the answer is 125 Nm, that is the EH Series.
Electric Rotary Actuator Products
High-torque electric rotary actuators designed for high vibration, shock, and continuous duty applications.
Compact electric rotary actuators for OEM applications requiring reliable quarter-turn control in harsh environments.
Frequently Asked Questions
What is a rotary actuator?
A rotary actuator is a device that produces controlled rotational motion over a fixed angle, typically 90 degrees. It is used when precise angular positioning and defined torque are required.
How is a rotary actuator different from a gear motor?
A gear motor rotates continuously, while a rotary actuator is designed to move to a specific angle and stop. Rotary actuators include internal stops and are optimized for positioning rather than continuous motion.
How much torque do electric rotary actuators provide?
Electric rotary actuators are available in a wide range of torque outputs. The actuators on this page range from 25 Nm to 125 Nm, covering many valve and positioning applications.
What is a quarter-turn rotary actuator?
A quarter-turn rotary actuator rotates 90 degrees from one end position to the other. This is commonly used for ball valves, butterfly valves, and dampers.
What control signals do electric rotary actuators support?
Electric rotary actuators can support analog signals such as 0–10 V and 4–20 mA, digital control such as PWM, and fieldbus protocols such as SAE J1939 CAN.
Can rotary actuators operate in harsh environments?
Yes. Rotary actuators designed for harsh environments can operate under vibration, shock, wide temperature ranges, and exposure to moisture when properly specified and sealed.
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