GBR Systems Corp. (Chester, CT) manufactures paper-handling equipment used by printers, marketers and direct mail companies to cut, fold and stitch their printed materials.

Recently, one of its machines began having problems because of the setscrews the company was using to secure a high-speed drive pulley to a 3/8-inch shaft. Specifically, GBR Systems found that the setscrews were loosening over time as a result of repeated clutching and braking at high speeds. This, in turn, would cause the machine to malfunction, often damaging the drive belt. Customers found themselves constantly having to retighten the setscrews, which resulted in lost productivity and increased maintenance costs.

To solve the problem, GBR Systems began securing the pulleys to the shaft using the Concentric Maxi Torque (CMT) system from drive and pulley manufacturer Custom Machine & Tool Co. (Weymouth, MA).

Comprised of a single screw and a hub with a tapered bore to match the CMT bushing, the CMT system allows for precise component positioning and tight runout control for demanding applications. Assembled parallel to the shaft, the system is easy to install, provides a positive connection without damaging the shaft, and eliminates the need for the secondary machining required by setscrews.

In operation, GBR System’s customers found that maintenance costs and downtime were dramatically reduced when supplied with pulleys using the CMT system.

First introduced in 2000, the CMT system can be used to secure timing pulleys, gears, sprockets, pinch rollers and couplings. It is available in 12 sizes for bores ranging from 0.125 inch to 1.187 inch.

With typical radial runout of less than 0.001 inch as assembled, the CMT system enables machine builders to attain higher drive speeds, reduce vibration and maintain concentricity. The mechanical shrink-fit approach of the CMT system provides a torque capacity far exceeding that of a two-setscrew arrangement, thereby offering a robust and reliable connection.

In addition, its compact design eliminates the need for the extended hubs often required to accommodate conventional setscrews, saving space and weight and shrinking design envelopes.

For more information on CMT pulleys and hub-to-shaft connections,