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Precision lock nuts with locking pins

KMT and KMTA lock nuts are intended for applications where high precision, simple assembly and reliable locking are required1. The three, equally-spaced locking pins enable these lock nuts to be accurately positioned at right angles to the shaft. However, they can also be adjusted to compensate for slight angular deviations of adjacent components.

KMT lock nuts

  • are available for thread M 10x0,75 to M 200x3 (sizes 0 to 40) and Tr 220x4 to Tr 420x5 (sizes 44 to 84) (fig. 1)

KMTA lock nuts

  • are available for thread M 25x1,5 to M 200x3 (sizes 5 to 40) (fig. 2)
  • have a cylindrical outside surface and, for some sizes, a different thread pitch than KMT lock nuts 
  • are intended primarily for applications where space is limited and the cylindrical outside surface can be used as an element of a gap-type seal

Features and benefits

  • Maximum axial run-out between locating face and thread (up to size 40): 0,005 mm
  • Adjustable to compensate for slight angular deviations (fig. 3)
  • Fine thread pitch
  • Withstands high axial loads
  • Reliable, effective locking mechanism
  • Simple installation and removal
  • No keyway required1
  • Reusable
  • Designed for frequent installation and removal

The locking principle

KMT and KMTA series precision lock nuts have three locking pins equally spaced around their circumference (fig. 4, fig. 5 and fig. 6) that can be tightened with grub screws to lock the nut onto the shaft. The end face of each pin is machined to match the shaft thread. The holes for the locking pins and grub screws are drilled with their axis parallel to the loaded flank of the shaft thread (fig. 7). The locking screws, when tightened to the recommended torque, provide sufficient friction between the ends of the pins and the unloaded thread flanks to prevent the nut from loosening under normal operating conditions (→ Product data). Because the locking pins are tightened against the unloaded flank of the shaft thread, they are not subjected to any application loads imposed on the nut.
  1. 1)KMT and KMTA lock nuts should not be used on shafts with keyways in the thread or adapter sleeves. Damage to the locking pins can result if they align with either.
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