A rotary actuator – sometimes referred to as a rotary drive, rotary cylinder, swivel drive, or slew drive – converts hydraulic pressure into limited-angle rotary motion.
It delivers maximum torque in minimal space, allowing heavy loads to be rotated, pivoted or positioned with precision.

Rotary actuators are used wherever controlled angular motion is required – for example, to rotate a digging bucket, open a heavy safety door, or position a work platform.
They typically operate over angles between 45° and 360°, and special designs can even reach up to 1440°.

Eckart Hydraulics has been a benchmark in this field for over five decades.
Its rotary actuators are frequently referenced in technical publications and trusted worldwide for durability, precision, and reliability.

According to ISO 5598, a rotary actuator is defined as a device that converts hydraulic or pneumatic energy into limited rotational movement.
In Eckart Hydraulics actuators, this movement is generated inside a compact, sealed housing where hydraulic pressure acts on a piston with a helical spline.
The piston’s linear motion is transformed into smooth, powerful rotation of the output shaft.

This design provides:

• Extremely high torque density
• Precise, repeatable angular control
• Constant overall length regardless of angle
• Compact installation space

Eckart actuators operate safely between 20 – 250 bar (290 – 3625 psi), ensuring continuous performance under demanding industrial conditions.

What is the helical gear principle?

In some online sources, terms like “steep thread” or “steep gear” may appear – the correct technical term is helical gear or helical spline.
In Eckart Hydraulics rotary actuators, the helical angle of the spline teeth converts the piston’s linear movement into highly efficient rotary motion.

Advantages of the helical gear principle:

• Outstanding torque in a compact format
• Exceptional holding power and stiffness
• High positional accuracy
• Simplified mechanical integration

While the principle is elegant in its simplicity, its implementation requires micron-precision machining and deep hydraulic expertise – both hallmarks of Eckart Hydraulics.

Helical Spline Actuator
This actuator converts the linear movement of a piston into rotation through a helical spline.
Operating pressures range from 20 bar to 250 bar, making it ideal for compact, high-torque applications such as those based on the Eckart Hydraulics principle.

Vane Actuator
Here, a rotating vane divides two pressure chambers.
It is mainly used in pneumatic or light-duty systems, typically at 50 to 100 bar.

Rack-and-Pinion Actuator
In this design, a linear rack drives a pinion to create rotary motion.
Common in industrial valve automation, it operates between 100 and 210 bar.
However, the external gearing and multiple moving parts make it more susceptible
to wear and leakage under continuous load, which is not uncommon compared to the compact helical-spline designs.

Swivel / Slew Drive
A gear-based mechanism providing limited rotation, often at pressures up to 250 bar.
These systems are suitable for large-scale or low-precision applications,
but due to their size, backlash, and sealing complexity, they are less efficient
and less precise when high torque and repeatable accuracy are required.

For more than five decades, Eckart Hydraulics has been shaping the development of rotary actuators, hub-rotary units, and multi-axis drives.
We are not just manufacturers – we are engineering partners who work closely with equipment manufacturers and system integrators to develop the right actuator for each application.
This approach has made Eckart Hydraulics a trusted choice in industries where heavy-duty truly means heavy-duty.

Our experience from demanding environments such as mining, tunnelling, energy production, and offshore installations has taught us exactly what long-term reliability requires.
Every actuator we produce incorporates knowledge gained from thousands of real-world applications – refined through decades of field experience and continuous in-house research. Our R&D teams focus on materials science, tribology, and sealing technology, ensuring every new generation of actuators performs with even greater efficiency and durability.

Eckart Hydraulics actuators are not off-the-shelf components.
Each model – from SM4 and E3 to the HyRAV valve actuator, and the 2AxA and 3AxA multi-axis systems – is purpose-built for industrial use, combining compact dimensions with outstanding torque, precision, and longevity.
This philosophy results in drives that perform reliably under extreme loads and environmental conditions,
particularly where combined rotary and linear motion is essential.

More than half a million actuators in operation worldwide speak for themselves.
They are used in safety-critical applications such as rescue systems, valve automation, aircraft testing, ship hatches, and heavy construction machinery.
Particularly in underground and mining operations, Eckart Hydraulics actuators are part of safety-relevant systems – from drilling rigs and scraper conveyors to wheel loaders and large-scale excavators.
Across the globe, Eckart components ensure reliable motion wherever heavy-duty performance and absolute dependability are essential.

Top-grade materials, high-precision manufacturing, and lifelong support are standard features of every Eckart actuator. In short, Eckart Hydraulics combines engineering depth, proven field performance, and uncompromising quality — for actuators built to last.

Rotary actuators find applications in various sectors and industries. Our motors are used in construction machinery, vehicle manufacturing, power plants, the food and pharmaceutical industries, underground, on land, and on water.

A special form of rotary actuator is the linear-rotary actuator. In this case, the classic rotary motor is combined with a double-acting linear cylinder. This allows both rotary and linear movements in a confined space. Eckart Hydraulics offers the HSE4 linear-rotary combination, providing full flexibility in tight spaces.

Both units can be controlled hydraulically separately. This enables all possible movement sequences: pivoting left and right, linear extension and retraction. Because the rotary actuator and the linear cylinder can be controlled simultaneously, movements can also be executed synchronously or in any combination as required for the application.

It goes without saying that for these complex and diverse applications, customizations are often necessary. At Eckart Hydraulics, this is part of our fundamental concept. We fulfill customer wishes 100%. You can have a rotary actuator custom-made by us, precisely according to your requirements with our expertise, and as little as one piece.

Each specially tailored drive is based on our proven three model series: SM4, E1, or E3.