The 785 Gear Rack Kit uses a Hitect HS-785HB rotational servo to create linear motion. Just send the correct PWM signal from your servo controller and any attachments will glide down the track. Made of aluminum Actobotics components and Delrin plastic, the kit is durable and lightweight.
The HS-785HB servo rotates approximately 1.7 degrees/microsecond change in signal. For maximum distance, a signal range from approximately 850-2150usec is needed. On a standard RC transmitter and receiver, components attached to the Gear Rack will travel approximately 6.7 inches.
The ServoCity 785 Gear Rack Kit can be purchased online for $89.99.