The SR31 from Exlar Corp. is an inverted roller screw actuator with a lead accuracy of 0.001 inch per foot. It converts rotary motion from a brushless dc motor into linear motion in aircraft-assembly riveting and flight simulators.

"It's a roller screw with a motor wrapped around it," says Brian Bendel, a design engineer at Exlar. "We took the nut and made it into the motor's rotor, then attached a screw to the rod that comes out of the actuator end."

The SR31 is suitable for use in closed loop servo systems where electronic control of positioning and velocity is required. Quadrature encoders provide the position feedback.

The actuator has a 3.3-inch frame size, stroke lengths of 5.9 and 10 inches, and motors with either 20 or 30 in-lb torque. Depending on the motor used, the SR31 has between a 225 and 900 lb thrust capacity. It operates at 10 and 25 inches per second linear speed.

All converting components are mounted within a sealed IP54-rated housing. The housing is made from black anodized aluminum.

A smooth extending rod allows use of a bushing and seals that prevent abrasive particles and other contaminants from entering the actuator's mechanisms. The SR31 replaces ball screws, cams, and hydraulic and pneumatic cylinders. Other characteristics for the linear actuator include front-flange or rear-clevis mounting and shielded cables. The company configures the actuators for compatibility with different brands of servo amplifiers.

Additional Details...Brian Bendel, Exlar Corp., 1470 Lake Dr. W., Minneapolis, MN 55317; Tel: (952) 368-3434; FAX: (952) 368-4877; www.exlar.com or Enter 576