In its simplest form, a rotary actuator is a device that uses hydraulic fluid to generate rotary motion without a linkage. These devices come in handy when applications call for any form of transporting, securing, or positioning of parts. 

How Do Rotary Actuators Work?

In terms of design, rotary actuators are most often configured as vane type, rack-and-pinon type, or helical spline actuators.

Our 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. Helical spline actuators function when the piston is axially displaced using hydraulic pressure causing simultaneous rotation of the piston.

Hydraulic rotary actuators are typically designed to operate at low speeds and produce high torque through arc lengths ranging between 90°, 180°, 270°, and 360°. They also can be configured up to 720° or more by making the spline gears longer while maintaining the same diameter.

Common Applications of Rotary Actuators

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.

One common application is using a 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. 

Additionally, 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.

A rotary actuator could also be used for gate valve control too. While a hydraulic 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.

Hydraulic Rotary Actuator Benefits

Hydraulic rotary actuators are known for their strong ability to produce power quickly. In comparison to pneumatic and electric rotary actuators, hydraulic actuators are the most powerful and have the capacity to achieve a torque output up to 2,200,000 Ibs-in (250,000 Nm) as a helical spine actuator and even higher as a rack and pinion actuator.

Rotary actuators also require a minimal amount of space while delivering high performance and flexibility due to its compact design. They also have high-efficient end cushioning and wear-resistant sliding surfaces.