Hydraulic & Electric Actuation Systems Comparison
Actuators have long played an important role in nearly every type of machine with moving parts converting some sort of energy into the motion that allows machines to operate and perform the functions they are designed for.
They are essential for many different types of mobile and industrial equipment and manufacturing operations. In addition, more recently, they are being incorporated into many robotic and automated machines.
Actuation systems are classified by the type of motion they produce, i.e. linear or rotary, and by the type of energy source they use to produce motion. Two of the most popular types of actuators are hydraulic-driven and electric-driven, each with their own advantages and disadvantages.
Hydraulic Actuation Systems
Hydraulic actuators operate by using pressurizing fluid and converting it to linear or rotary motion. They generally incorporate a hydraulic power unit (HPU), valves that divert fluid flow, hoses that connect with cylinders, and cylinders that perform the work. These systems are known for their high-power density, robustness and up-front cost effectiveness and are most commonly used for heavy duty work. Forces and speeds of hydraulic actuator systems can be increased by sizing the HPUs with larger motors, pumps and reservoir tanks that allow them to be used on very large systems.
Hydraulic actuator systems have drawbacks. The major issue with these systems is their tendency to leak creating unplanned downtime, extensive maintenance, and safety concerns. In addition, hydraulic systems are not energy efficient, often running continuously and have efficiency losses from fluid flowing through hoses, valves and fittings. To maintain operating performance, hydraulic systems need periodic fluid changes that create environmental issues from waste oil disposal and significant expense for disposal and replenishment.
Electric Actuation Systems
Electric actuators, often referred to as electro-mechanical actuators (EMAs), utilize electric power to energize an electric motor that converts the energy into torque. These systems are made up of several mechanical components including screws, bearings, drive nuts and gears. They’re known for being very responsive, precise and are best suited for light or medium duty applications.
When used as an alternative to hydraulic actuators, electric actuators eliminate the potential for leakage and use ‘power on demand’ that saves on energy consumption.
The drawbacks of electric actuators are that they have a much lower power density than hydraulic systems and are limited to applications that do not experience shock loads, side loading or concentrated loading. Their complex mechanical design and higher number of components increases the risk for unplanned breakdowns, and they require regular maintenance and lubrication to prolong operating life.
Kyntronics’ SMART Electro-Hydraulic Linear Actuator
Considering the high operating costs and other challenges associated with hydraulic and electro-mechanical actuation technologies, Kyntronics decided to develop an alternative actuator technology. We combined the best features of both actuator types while eliminating the inherent disadvantages of both.
The Kyntronics SMART Electro-Hydraulic Linear Actuator (SHA) is a servo motor-driven actuator that utilizes an internal pump, hydraulic cylinder and a small amount of fluid. It is a totally sealed system that does not require fluid changes. The SHA provides highly precise control of position, force and speed and high force operation rated up to 150,000 LBs (667 kN) of force.
The totally sealed system design eliminates leaks and is highly energy efficient utilizing power-on-demand operation. The internal cylinder allows the SHA to be used on applications having shock load and side loading risk without damaging the actuator. Preventative maintenance is limited to a rod seal change after 50,000,000 inches of travel.
The SHA improves process quality control, provides data for analysis, reduces maintenance, supports IoT and Sustainable Manufacturing.
