Introduction to Hydraulic Rotary Actuators
Hydraulic rotary actuators provide high‑torque rotary motion in a compact, sealed housing, making them an ideal solution when you need to move, hold, or position heavy loads in tight spaces.
Based on the real‑world applications and challenges we support as a hydraulic distributor, this page highlights how these actuators are actually used and which specs matter most when you’re selecting one for your design. Explore common use cases and the most frequently asked questions we get when talking about rotary actuator basics.
Hydraulic Rotary Actuators 101
What are Hydraulic Rotary Actuators?
In its simplest form, a hydraulic rotary actuator is a device that uses hydraulic fluid to generate rotary motion without an external linkage. These devices come in handy when applications call for any form of transporting, securing, or positioning of parts.
How do Hydraulic Rotary Actuators Work?
In terms of design, hydraulic rotary actuators are most often configured as vane type, rack-and-pinion type, or helical spline actuators.
IC-Fluid Power’s rotary actuators are the helical spline design. This means, a piston and a helix, or sliding spline, work together to convert the linear motion of the piston into rotational motion.
Hydraulic rotary actuators are typically designed to operate at low speeds and produce high torque through various custom and standard arc lengths. They can be configured up to 720° or more by making the spline gears longer while maintaining the same diameter.
What Are the Advantages of a Helical Spline Actuator?
Helical designs bring several practical advantages for hydraulic actuator applications. The compact design fits where bulky linkages cannot, making them ideal for tight mobile and off‑highway installations. All moving parts are sealed inside the housing, so there is less risk of contamination, corrosion, and fewer failure modes than with exposed systems, plus fewer pinch points for improved safety. Internal components run in a constant oil bath, creating a self‑lubricating machine with low maintenance needs that withstands heavy cycling and offers a long service life.
Due to the piston and helix design, the actuator exhibits high torque, excellent holding power, and accurate positioning in a single, space‑saving unit.
To get a look at the inner workings and to see how the helical gears function, check out this video. To learn more about how these actuators have fewer failure modes and pinch points, check out the linked videos.
Common Applications
From manipulating the angle of a boom in construction applications to opening or closing flaps in the aircraft and aerospace industries, rotary actuators are dependable and durable devices used for a wide range of uses.
Simple Tool Changes
Gate Valve Control
Tipping Devices
Simple Tool Changes
Hydraulic rotary actuators can function as simple tool changers. One example of this is using a rotary-linear actuator for a pallet changer that weighs 1,000 kg. This device is a combination of a rotary actuator and a dual-action linear cylinder, allowing for full flexibility in a minimal amount of space. Since the rotary actuator and the linear cylinder are hydraulically driven separately, any movement sequences can be selected: for example, rotating to the left and right, extending linearly, and retracting.
Gate Valve Control
A hydraulic rotary actuator could also be used for gate valve control too. While a rotary actuator may be more expensive than pneumatic actuators, these devices have a higher level of precision, require less space, and can achieve high torque outputs. Other uses for rotary actuators include linear actuation, bending machines, work piece positioning, rotational devices, and transport applications.
Tipping Devices
One common application is using a hydraulic rotary actuator for tipping devices. A helical rotary actuator, for example, would be a suitable option for bin tippers in waste management applications due to its high torque in a compact package.
One example of this is in the refuse/waste and recycling tipper market where standard degrees of rotation for tippers include 135° or 180°. The IC40 Series, however, offers rotations of 200° and 220°, adding more extension to the tipper to dump the components of the waste receptacle entirely.
Heavy-Duty Motion Control
A very common use case for hydraulic rotary actuators is heavy-duty motion control and attachment positioning. These are used in a handful of industries like forestry, agriculture, mining, and more.
In forestry, actuators (IC10s) are used in forest and felling equipment to move components, such as grapplers or boom arms, in tree removal and timber harvesting applications.
In agriculture, actuators (IC20s) create rotational movement and control for just about any farm machinery, from folding attachments for on-road transportation to positioning the nozzle of a mobile sprayer in place.
In mining, actuators (IC30s) manipulates the drill arm and has a 360° rotation, enabling a full range of movement where the drill arm might need to create blast holes from the ground to the ceiling.
How to Choose the Right Hydraulic Actuator
Different actuator models typically depend on the system’s operating pressure. This is why it’s important to know the pressure required, along with other key factors including load capacity, rotation angle, rotation speed, and more.
Operating Pressure
First, determine the operating pressure. This is important to ensure the actuator is rated for the system pressure being used.
Torque
The amount of torque helps determine how the actuator will perform and how much it can handle, especially in terms of load capacity. The higher the torque output, the more load capacity the device will have.
Dynamic Movement
Next, determine if the rotary actuator will be used in highly dynamic applications, such as torque/torsion testing. If so, end-cushioning is important to have, along with a servo valve that can be mounted to the actuator to offer more control to the device.
End-Cushioning
End-cushioning is an important factor to consider for highly dynamic applications, such as when the actuator needs to function as an end stop in a load. End-cushioning acts as a hydraulic break to slow down the movement of the actuator so that it doesn’t slam into the end position causing damage to the device or the workpiece. The end-cushioning effect can be finely tuned using built-in orifices and set screws.
Mounting
Actuators can be mounted in different ways, along with different shaft styles. The actuator might have a flange mount, foot mount, or threaded holes in the actuator body. The shaft could be male or female with spline, key, or other shapes; as well as flange style.
Temperature
Typical hydraulic systems operate in an oil temperature range from -4°F to +240°F (-20°C to +60°C) in the same range. Actuators operate in the same range. If actuators need to operate above or below the standard temperature range, then special steels or special seal material may need to be used.
Mediums
The same applies to different mediums. Different mediums could require non-standard seals and different actuator materials.
Side Loads
If the application and actuator have side loads, the side loads need be absorbed separately from the actuator, or the actuator needs to be designed to accommodate the side loads. This is often done through the use of bearings. Eckart usually includes 4-point contact bearings as standard.
General Applications
Finally, it’s important to understand the general application. For example, will the device be going offshore? This might require special paint and special seals to protect the actuator from harsh seawater environments. As mentioned above, it’s important to know if the actuator will be used in testing applications, as special attention would be needed to make low-friction seals and a servo valve adapter plate.
Buying Rotary Actuators from a Distributor
When you buy a hydraulic rotary actuator from a distributor, the most important factor is how well the actuator is matched to your system and application. The right fit for one consumer might vastly differ from the needs of someone else. Some customers need a replacement part that can get there quickly, while others need heavy-duty actuators with highly customized features. A good distributor will help translate your operating pressure, required torque, rotation angle, mounting style, and environmental conditions into a specific model and configuration. This is especially critical with heavy-duty or custom actuators, where options for bearings, end‑cushioning, shaft styles, seals, and surface treatments can significantly change performance and service life.
It’s also useful to understand how the distributor works with their manufacturers. Strong relationships can shorten lead times, open up niche product offerings, and indirectly connect consumers to the engineers who design and build the actuators. For engineering and procurement teams, that means a single point of contact who can troubleshoot applications, coordinate directly with manufacturers, and deliver solutions that fit specific needs and requirements.
Another benefit of buying rotary actuators from a distributor is the range of products they can procure. Instead of shopping around for a single solution, working with a distributor can mean coming with a problem and being offered several solutions. There’s less heavy lifting and more options, including international technology not available in North America.
With decades of experience, Eckart can design and build a quality rotary actuator to your specifications.
The SM4 rotary actuator with an operating pressure of up to 250 bar offers rotary movement with a compact footprint.
The E3 with a maximum operating pressure of 210 bar, is designed for, but not limited to, mobile applications where a flange shaft is desirable.
The E1 rotary actuator with an operating pressure of up to 100 bar offers rotary movement with a compact footprint.
The HyRAV® valve actuator is tailored perfectly to your needs. HyRAV by Eckart, comprises a full series of double-acting or spring return actuators.
The HSE4 rotary-linear actuator combines an independently controllable dual acting cylinder with a rotary actuator.
The PSM2 pneumatic rotary actuator is most suited to applications in small installation spaces with low weight specs.
The Eckart PHSE pneumatic rotary-linear actuator is a combination of a rotary actuator and a dual-action linear cylinder.
Optional load holding valves for intermediate position holding and over center conditions.
