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By Charles J. Murray, Senior Regional Editor -- Design News, April 5, 1999
Clutch-pulley cuts automotive belt noise
Conventional automotive drive belt assemblies have long provided the power to run alternators, air conditioners, and other accessories. They can, however, suffer from excessive noise. So-called "belt chirp" occurs when accessories overrun the belt during large changes in engine speed. To deal with that problem, engineers at NTN Technical Center have developed an overrunning clutch-pulley for use with automotive accessories. By installing a one-way wrap spring clutch into the pulley assembly, they can decouple accessories during overrunning conditions. Typically, they apply it at the vehicle's alternator. The key, say NTN engineers Randall King and Russell Monahan, is their use of the wrap spring clutch, instead of a roller clutch or sprags. The wrap spring mechanism offers low cost, durability, very high torque capacity, and better performance in a "free-wheeling" mode. NTN Bearing Corp. of America: Product Code 4662
Simplified electro-pneumatic connections
Connecting a ball screw to a pneumatic slide usually isn't easy. In most cases, it requires the addition of a custom adaptor plate that fits between the two components. Now, however, Numation Inc. (Avon, OH) offers a new ball screw gantry with a patented mounting system that enables pneumatic components to mate with electrical products without transition plates. The mounting system, known as NuMate, simplifies the process of connecting two or more working axes. "It eliminates additional cost, installation time, and design time associated with adaptor plates," notes Jeff Schneid, president of Numation. Schneid says that the ball screw gantry and NuMate mounting system can be applied to insertion, load/unload, multiple positioning, and controlled-speed applications. Numation Inc.: Product Code 4666
AC drives available via Internet
Engineers can now purchase ac drives ranging from 0.5 to 50 hp by connecting to the Internet. In the first arrangement of its kind, ABB Drives and Power Products has enabled users to customize drives by power rating, phase, voltage requirements, and other application particulars while on line. A family of low horsepower drives, known as Comp-AC, is available at the site. The family includes: ACS 100, for motors ranging from 0.5 to 3 hp, 230V, single- or three-phase; ACS 140, for 0.5 to 3 hp, 230 to 460V ac, single- or three-phase; and the ACS 400, which serves motors from 3 to 50 hp. Those drives typically serve in a variety of applications, including pulp and paper, converting, textile, and mining, among others. ABB says that the web site's selection process is similar to the kind used by automakers for choosing options on a car. Users fill out a matrix of application requirements in a 10-step process, then return it to ABB for an immediate price quote. ABB Drives and Power Products: Product Code 4663
Modular drive is easy to customize
Unfortunately, industrial drives don't always conform to every industrial enclosure. To address the packaging issues that arise when users try to mate drives and enclosures, engineers from MagneTek have introduced a new unit featuring a modular design. Known as the GPD 515 drive, it employs a "building block" approach that offers commonality of parts for applications ranging from 400A to 1,600A. The building block approach enables engineers to configure the drive for a specific enclosure, or for a specific power requirement. Commonality of parts makes it easy to add modules, thus changing the shape, power output, or current drive characteristics. The GPD 515 serves in applications up to 1,500 hp, including pumps and fans, chillers, pulp and paper manufacturing, mining industry conveyors, rock crushers, and extruders. MagneTek: Product Code 4665
Magnetic coupling protects machinery
For decades, engineers have employed mechanical safety couplings as a means of providing overload protection. But while mechanical couplings do a good job, they can wear out in high-frequency applications. "Mechanical couplings are not designed to engage and disengage a thousand times a day," notes Vic Jha, general manager of Rimtec Corp. (Westmont, IL). To meet the need for greater wearability in certain applications, Rimtec has introduced the MKD family of synchronous magnetic safety couplings. The couplings use rare earth magnets and air gaps instead of the traditional mechanical means. As a result, they can disengage without wear. The synchronous line transmits torques from 10 lb-inch (1.2 N-m) to 1,330 lb-inch (150 N-m). The units are said to be ideal for plastic injection molding machines, packaging machinery, and a wide variety of servo applications. Notes Jha: "If the disengagement frequency is high, you're better off with a magnetic coupling." Rimtec Corp.: Product Code 4664
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