A heavy duty actuator is a fairly generic term used to describe actuators used in applications requiring extreme torque outputs. Defining the exact parameters for the term is difficult, as a heavy duty actuator in one application may be hopelessly underrated in another. Generally speaking, however, the heavy duty actuator may be classified as one capable of producing 1,000 pounds (454 kg) or more of pressure at the actuation point. Heavy duty actuators are available in a number of configurations, including rotary and linear types, with a range of power sources, such as electric, pneumatic, and hydraulic. Although hydraulics have historically been the obvious choice of power source due to the high output rating of hydraulic units, electric actuator technology has advanced to the point were they are also well-suited to these demanding applications.
Actuators used to control earth-moving equipment, high pressure valves, and heavy process machinery are often required to produce outputs rated in thousands of pounds. These heavy duty actuator types are also typically exposed to extremely hot, dusty, and corrosive environments, so they need to be tough and resilient as well as powerful. To this end, they have traditionally been ruggedly build with heavy seals, actuator arms, and internal mechanisms built to exacting standards.
The exact definition of a heavy duty actuator is difficult to quantify. It is safe to assume that any actuator capable of exerting 1,000 pounds (453.6 kg) or more of pressure may be classified as being heavy duty. It is not uncommon for actuators used on ultra-heavy earth-moving machines, for instance, to have ratings of 5,000 pounds (2,268 kg) or more. Actuator types in this category are represented by both linear and rotary output examples with a range of possible power sources. These include electric, pneumatic, and hydraulic actuators, with the hydraulic types being the traditionally favored choice.
Although hydraulic variants have long been considered the ultimate heavy duty actuators, other options are now becoming serious contenders on the back of material and engineering advancements. Electrically-driven heavy duty actuator examples are now capable of producing the high output values previously only associated with pressurized oil systems. In addition, they tend to be a lot quieter than their counterparts and also run cooler with no leaks. This not only makes them viable alternatives, but also, in some cases, superior to their hydraulic peers. In the case of high-pressure butterfly and ball valves, however, the hydraulic quarter-turn actuator is still considered to be the preferable heavy duty actuator.