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AME Offers Unique Locknut Design

Improves efficiency and bearing reliability on industrial compressors and other applications; positive locking WITHOUT washers and keys; supports extreme thrust loads

Advanced Machine & Engineering Co., (AME) Rockford, IL provides its unique Spieth locknuts for accurate rotor positioning and reliable thrust bearing retentionon compressors, shafts, spindles and other industrial/commercial applications, in a unique engineering achievement.

In a compressor application, for example, the locknut can play a key role in establishing the clearance between the rotor and the compressor housing, where too little clearance causes seizure, while too much reduces compressor efficiency, due to leakage around the rotor body.

While the standard Spieth locknut configuration had considerable appeal for the application, several design refinements were deemed highly beneficial for this application.  “We liked the positive locking feature without washers and keys, plus the locknut’s ability to support extreme thrust loads by providing full 360º contact around the thread flanks,” according to one application engineer contacted for this story.

Key features that led to one compressor manufacturer’s selection of the Spieth product from AME included:

  1. Square face to thread precision, for better bearing reliability and compressor efficiency, due to accurate rotor positioning
  2. Lock screw adjustment does not reduce end clearance or negatively impact reliability
  3. Absolutely no locknut movement in operation
  4. AME’s flexibility to cost-effectively customize the design for the application
  5. AME’s product quality and delivery performance record

The full circumference contact of the Spieth locknut was designed to ensure the locknut would not back off, even when subjected to extreme shock loads.  It further aligns its contact face with either a zero runout or, as needed, it can be adjusted to suit the inaccuracies of the in-line connecting components, thus compensating for minor errors of parallelism due to the stack-up of mating parts.  Uneven bearing loading is thus compensated and its impact minimized.

The basic design of the Spieth adjustable locknut involves two axially arranged radial grooves, one from the outside and one from the inside, which result in a diaphragm-like cross-section to give the locknut a predetermined axial elasticity.  The internal groove divides the locknut into a clamping and a locking section.  Depending on the nut size, multiple axially arranged socket head set screws are used to clamp the sections together.  This eliminates the thread flank clearance between the rotor and the locknut, allowing for shockproof clamping.

In installing the locknuts, a consistent tool torque setting was found sufficient to achieve parallel locknut body and threads. Thus, the face of the thread flank and centerline of the shaft were always in ideal alignment.  This was done to provide a square thrust collar for thrust bearing reliability and rotor positioning.

Other applications for Spieth locknuts typically include shaft and spindle retention on bearings, where displacement, axial preload and clearance issues are critical.  The unique design of this locknut ensures no back-off, even when subjected to extreme shock loads.  In machine tool and heavy equipment use, for example, spindle runout due to uneven bearing loads can be eliminated, due to the full 360º contact around thread flanks.  Spieth heavy-duty locknuts can be used with needle and roller thrust bearings, plain thrust bearings or taper roller bearings on ballscrews, worm drives, bevel gears and other high-thrust carrying components.

For technical questions on this article, please contact Shane Hatfield (shane@ame.com) at AME.

Advanced Machine & Engineering Co., is a manufacturer located in Rockford, IL, serving the Machine Tool Industry with precision components and accessories, including spindle interface components, workholding devices, and, through our sister company, Hennig, machine enclosures, chip removal and filtration systems.  The Fluid Power – Safety markets are served with cylinder rod locks and safety catcher devises; and the Production Saw market with our Amsaw carbide saw machines and Speedcut blade products.  AME has manufacturing partners and customers around the world and across the U.S.  To learn more, visit www.ame.com.

Hennig, Inc. design and produces custom machine protection and chip/coolant management products for state-of-the-art machine tools.  Hennig products are designed to protect against corrosion, debris and common workplace contaminants.  Manufacturing facilities located in the U.S., Germany, Brazil, India, Japan, China and South Korea.  Repair centers are located in Machesney Park, IL; Chandler, OK; Livonia, MI; Blue Ash, OH; Mexico City, Mexico and Saltillo, Mexico.  To learn more, visit www.hennigworldwide.com.

For more information, contact:

Tim Waterman
2500 Latham St.
Rockford, IL 61103
Phone: 815-316-5277
Fax: 815-962-6483
E-mail: info@ame.com

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