The triennial IFPE show, scheduled for March 7-11 in Las Vegas, is an opportunity to learn more about the latest in hydraulic rotary actuators. Following is a description of how and why you use them in mobile machinery, as well as a listing at bottom of what IFPE booths you can visit for more information on these very useful actuators.
Rotary actuators provide torque movement through a limited range of motion, contrasting with hydraulic motors, which can rotate in one or two directions indefinitely. Rotary actuators are used in any application where a known arc of travel is to be achieved repeatedly and accurately, such as the swing arm on a conveyor or the rotation of a boom crane.
Rotary actuators have two main configurations, using either cylinders or internal vanes. The cylinder style actuator has two opposed hydraulic pistons, attached with a common spur gear rack. Each of the two pistons can push toward the opposite piston, pushing the rack across the pinion, rotating the mechanism. The degrees of rotation are limited by the stroke of the cylinder(s) and the number of teeth on both the rack and pinion. They are often sold in combinations of 90° rotations, with 360° typically as the upper limit. This type of rotary actuator is capable of high torque and load, but requires a lot of real estate because of the length of the cylinders. Often times, two cylinder/rack assemblies are juxtaposed to each other, each pushing in opposite directions and double the torque.
The second of the main rotary actuator types is the vane style, which uses vanes in a housing with stops in one or more locations. A single vane, for example, might rotate up to 270°, but with just one vane in the housing, it is limited in torque. A dual vane actuator will have two opposed vanes, enabling twice the torque but half the rotation.
Rack and pinion configurations typically handle more shaft load capacity, sometimes supporting large booms. This configuration can also be easily positioned, and stopped and started repeatedly at the same location. A vane type rotary actuator works well for indexing, moving the full length of its available rotation during every cycle, although electronics and closed loop control can enable them to be highly accurate in their positioning.
Rotary actuator manufacturers and suppliers at IFPE
(Please note, list may not be complete as changes are made regularly to the IFPE suppliers’ categories pages.)
Exhibitor Booth Number Helac Corp. C21053 HKS Dreh-Antriebe GmbH G72021 IC-Fluid Power Inc. S80406 Ligon Hydraulic Cylinder Group S82916 SungJi Hydraulics Co. Ltd. G73608