Replacing Pneumatic Clutch Brakes in High-Speed Feeder Rollers

In 1992, Chicago Dryer Company introduced a cornerless spreader/feeder, revolutionizing how commercial laundry is processed. Today, their Edge TriMaxx stands as the fastest laundry feeder in their product family, designed to separate, spread, and feed sheets into ironers with high precision. However, maintaining that precision over millions of cycles required overcoming the limitations of traditional pneumatic components.

For the Edge Series machines, the engineering team needed to control rollers that drive a sheet through, locate the last corner, and present it to the ironing machine. Originally, this function was driven by an induction motor utilizing a pneumatic clutch-brake to engage and stop the rollers. While the system functioned, the nature of pneumatics introduced performance variability over time.

This variability meant the stopping position, critical for properly spreading the sheet, could drift as components wore or air quality fluctuated. To ensure the machine met the high standards of Chicago Dryer’s customers, the team looked for a fully electronic alternative.

The application required the precision of a servo but did not warrant the complexity or cost of a full multi-axis motion control architecture. The goal was to find a device that could handle specific velocity profiles without occupying significant space in the machine.

The team selected Teknic’s ClearPath-MC, an integrated servo system. Because ClearPath combines the motor, encoder, drive, and controller into a single compact package, it saves cabinet space and simplifies machine wiring. Specifically, the ClearPath-MC series allows for precise velocity control and simple, yet high-precision positioning without the need for an external motion controller—ideal for replacing variable speed conveying applications.

A three-speed motion profile was configured triggered by machine sensors. The system is designed to "run the sheet through fast and then slow down a little bit and then just finish it off at a really slow speed," allowing the machine to maximize throughput while maintaining precise control.

By replacing the pneumatic clutch-brake with a direct-drive servo solution, Chicago Dryer eliminated the mechanical variables that caused timing drift. The friction and air pressure issues associated with the old design were replaced by closed-loop servo performance, eliminating long term variations in response.

Beyond the performance gains, the switch improved the operating environment of the machine. The new setup is "stable and quiet," removing the noise associated with pneumatic engagement.