Actuator torque is a quantitative expression of the amount of torque that an actuator is capable of producing. Torque is a term used to define the extent to which a motive force twists an object around its own axis or a fulcrum point. A good example of this is a high-performance race car which tends to twist or lift on one side when the engine is revved. This reaction is caused by the engine's torque, which, although its output force is harnessed to drive the car forward along its own axis, exerts a rotational movement around the car's axis. In simple terms, the more torque a device can generate, the more power it will be able to exert over a wider range of operational loads.
The straight line movement experienced when something is pushed is a practical manifestation of force. Torque, on the other hand, is best described as the result of the application of force to a wrench, which turns a bolt around its axis. The same applies to a screwdriver being used to loosen a very stubborn screw. If the screwdriver handle is well-designed and does not slip in the handyman's hand, a large amount of torque is being generated and applied to the screw by the force applied to the screwdriver handle. The same principles regarding the conditions that influence the ability of similar forces to generate rotary motion also apply to the definition of actuator torque.
Actuator torque is an important part of the rating specifications of any actuator. The torque rating of the device will dictate what type of applications the actuator will realistically be able to handle. A low torque rating will mean that the actuator will be able to maintain its output force over a very narrow load range. As soon as that range is exceeded, the actuator will be “smothered” and will not be able to continue exerting its working motion efficiently. In contrast, a high-torque actuator will be able to comfortably handle a far wider range of load variations.
This concept of actuator torque is perhaps best demonstrated by an automobile approaching a steep hill in top gear. In this gear configuration, the engine is not able to develop much torque and, to efficiently climb the hill, a lower gear will have to be selected. The same principle applies to an actuator with internal mechanism designs dictating how well the actuator motor translates its latent force into usable torque. High torque values are not always called for, so not all actuators develop the same torque outputs even though they may have similar power plants. This makes informed choices critical when selecting devices for applications requiring high actuator torque values.