Torque Transmission's Roller Chain Sprockets Help Darko's Display See the Light of Day

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Case history detailing how Torque Transmission helped solve a problem for a packaging and point of purchase customer.

Torque Transmission faced a major challenge in its quest to effectively help Darko Inc., in Twinsburg, Ohio, demonstrate Darko's latest point-of-purchase display -- Fisher-Price's GeoTrax train system.

"Time was of the essence because initial orders for the display ship out in mid-September," said Gary Rusnak of Torque Transmission's marketing department. "Fisher-Price requested that Darko have the display in place for Toys 'R' Us stores to begin promoting the toy during the coveted holiday buying season."

Darko, a leader in the development and production of point-of-purchase displays, interactivity and integration, custom fixtures, in-store environments and store reimaging, designed the display to have the GeoTrax train move back and forth on a straight section of track using an infrared controller.

Logistics became an issue as the display was constructed, preventing Darko from using the controller. Darko needed to create a mechanical device that mimicked the function of the controller. Under normal conditions, the battery-operated GeoTrax train cars are set on the tracks and move with the assistance of the controller, said Dave Ireland, Darko's engineering manager.

"We needed to demonstrate how the train moves back and forth along the tracks when using the remote control," Ireland said.

Faced with the dilemma of finding a method to accurately demonstrate the movement of the GeoTrax train system, Darko turned to Torque Transmission for help.

Torque Transmission provided the perfect solution -- its roller chain sprockets proved to be an ideal match to mimic the action of the controller. Once Ireland realized sprockets would help to power the GeoTrax train, he placed the production order for several hundred sprockets.

During the assembly process, Darko's engineers quickly discovered that part of the GeoTrax system interfered with other portions of the display. A decision was made to use a 1-inch, 25-pound pitch chain in a long, circular path that was wrapped around one of the Torque Transmission sprockets at each end. The chain went just far enough around the sprocket to drive the train.

To better assist Darko in its quest to produce a high quality display for Fisher-Price, Rusnak paired Darko with Connecticut-based POLYCLUTCH, a manufacturer of miniature clutches, brakes, motors and other motion control devices.

Darko's engineers utilized Torque Transmission's roller chain sprockets, placing a miniature POLYCLUTCH clutch within the drive of the sprocket. With the clutch in place, the sprocket was able to slip -- allowing for flexibility in the train's movement. This action permitted Darko to re-create the reverse movement of the controller.

"With the train securely fitted to the track, it was able to move easily across the track using the roller chain sprockets. The Torque Transmission sprockets provided Darko with the perfect solution for what it needed," Ireland said.

Torque Transmission's roller chain sprockets are manufactured with a glass reinforced nylon body that provides many features, including their availability in a wide selection of teeth from nine to 48 -- all single strand No. 25 inch pitch sprockets, Rusnak said. Hubs can be drilled with cross-holes for dowel pins or set screws.

Darko tested the display by running the train through more than 35,000 cycles. A cycle was measured each time the GeoTrax system, which was attached to a mechanical arm and a lever, moved forward, and then backward. Ireland said Torque Transmission's roller chain sprockets allowed the display to function exactly how it was designed to operate.

The Value To The Customer
An innovator with more than 50 years of designing and manufacturing custom and standard power transmission components for low and fractional drive applications, Torque Transmission was able to provide Darko with an equitable and cost-effective configuration to its problem. In this way, Torque Transmission delivered value and a viable solution to Darko when it needed it the most.

"Part of what we like to say is that we provide value by simplicity," Rusnak said, "With this part item, we did not have to go crazy and do special engineering or tooling to create a new product. Had we done so, the cost to Darko probably would have doubled. The value here lies in the fact that it was simple sprocket modified by a clutch -- and it worked perfectly for what Darko needed."

Because of the positive experience Darko had with Torque Transmission, Darko is well aware that it can find other quality Torque Transmission items -- like pulleys, gearboxes, and ball thrust bearings. These products will come in handy if Fisher-Price, or another company, challenges Darko to develop another working point-of-purchase display.

About Torque Transmission
For more than 50 years, Torque Transmission has designed and manufactured custom and standard power transmission components for low and fractional drive applications. Torque Transmission's wide product line includes worm gear speed reducers, right angle drives, thrust bearings, pulleys, roller chain sprockets, and flexible couplings. Our motion control components are used in industries such as food processing, medical, point of purchase, automotive, printing, semi-conductor manufacturing, sports and many others. For more information, call 800-544-6642 or visit

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Tom Mitchell
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