An actuator rod is the part of any actuator that physically transfers the actuator's mechanical output to the device it is designed to actuate. In most cases, this part is little more than a simple, straight metal bar or rod. Some actuator systems do, however, have fairly complex actuator rod assemblies consisting of several linkages. The design of the rod is largely dictated by the type of actuator, the output torque involved, and the type of device being actuated. Most medium- to heavy-duty actuator rods are made of metal, with lighter duty examples made of aluminum or various grades of plastic.
Actuators are used to provide working motion where human operators can't, such as in locations far from manned installations, in hazardous environments, and where space is limited. They are powered devices that may use electric motors, electromagnetic coils, and compressed gas or oil as power sources. As diverse as they may be in design and function, most of these devices transfer their working motion to their activated device via an actuator rod. This part of the actuator forms the physical link between the power output mechanism of the actuator and the device being activated.
These parts are, in most cases, fairly simple straight components manufactured from round or profiled stock. The large ram on a hydraulic cylinder used to tip the bucket on an earth-moving machine is a good example of a simple actuator rod. In contrast, the tiny plates that move the reader heads on a computer hard drive is also an actuator rod. Straight actuator rods are generally found on actuators, which produce linear, or straight line, outputs. These rods are, in many cases, simply an extension of the internal, power-generating mechanism of the actuator equipped with a yoke or locking pinhole on their ends for connection to the activated device.
Rotary actuators often have oval or half-round cams that transfer their working motion, with some examples being of a modular design, consisting of two or more separate pieces. In both rotary and linear output types, the actuator rod is most often constructed of steel or softer alloys such as brass or aluminum. Heavy-duty actuators that produce large amounts of torque will typically feature heavy, hardened steel rods capable of dealing with extreme loads. Light duty actuators may have rods made of composites or reinforced plastic. Many are hollow in cross section to save weight while benefiting from the inherent strength of cylindrical structures.