The US roller-screw specialist Exlar has developed an electric linear actuator which combines a precision inverted roller-screw actuator with a brushless servo motor and amplifier, position controller, and 230/415V power supply. This integrated design is said to eliminate the unreliable multiple connections needed for other servo linear actuators and to do away with the need for the 48V supply that some rival products require.

The Tritex II range, available in the UK from Olsen Engineering, consists, initially, of actuators with 90 and 115mm frame sizes, but larger versions are being developed. These will provide linear speeds from 127-953mm/s, forces from 738N-12kN and stroke lengths up to 455mm.

The actuators are aimed, in particular, at the food and beverage industry where the need for energy efficiency, reliability and cleanliness is persuading many manufacturers to move from hydraulic and pneumatic cylinders to electric actuators. The electrical systems avoid the infrastructure, maintenance and running costs of hydraulic and pneumatic systems, as well as their noise and leakage problems.

Although the electric actuators cost slightly more than their fluid power rivals, Olsen claims that the cost is offset rapidly by energy savings. It says that the actuators have an operating efficiency of more than 80% and use energy only when in operation.

The actuators can be programmed with up to 16 positions. In addition to the standard 8,192-count incremental encoder, an absolute encoder option is planned, as are various bus options.