When a wheelchair manufacturer revamped its powered leg-rest design, it wanted to overcome speed and power problems experienced by earlier versions. Invacare Corp., Elyria, Ohio, (www.invacare.com) chose compact electromechanical linear actuators from SKF, Bethlehem, Pa., (www.linearmotion.skf.com) for the job.

Invacare power wheelchairs feature a tilt-recline system, which moves and tilts individuals who are immobilized from the waist or neck down. Power leg rests compensate for lack of leg movement by helping relieve pressures created by sitting for long periods.

Earlier power leg rests used in-line actuators that had power and speed problems in the field. SKF provided a system to overcome these issues and support high loads. In addition, the new actuation system fits in a small design envelope.

In the application, two CAT 21 actuators mount either outside or under the wheelchair's leg rests, which lets them raise or lower as operated by the user from a main controller. The actuators run silently, deliver smooth movement over the full load range, and use reliable ball-screw technology.

What's more, a flexible design lets Invacare meet system requirements without time-consuming or costly customization. Critical internal and external components such as motors, screws, and attachments, can be interchanged for CAT 21 actuators without resorting to specially engineered parts, assemblies, and associated costs.