Installation and removal

KMT precision lock nuts have slots around their circumference to accommodate a hook or impact spanner (fig. 1 and fig. 2). The designations of the appropriate spanners are listed in the product table. For more information about the appropriate spanner, refer to Bearing fitting tools. KMT precision lock nuts with a thread ≤ 75 mm (sizes ≤ 15) have additionally to the slots two opposed flats to accommodate a spanner. Those lock nuts with a thread ≥ 80 mm (sizes ≥ 16) have six slots and no flats.
KMTA precision lock nuts have holes around their circumference and in one side face (fig. 3). They can be tightened with a pin wrench or a pin-type face spanner. Appropriate spanners in accordance with DIN 1810 are listed in the product table. KMT and KMTA precision lock nuts are designed for frequent installation and removal (provided they are not damaged).
  1. With the bearing in position, screw the lock nut into place.
  2. Tighten the nut with a hook or impact spanner making sure not to over tighten it.
  3. Tighten the grub screws carefully until the locking pins engage the shaft thread.
  4. Tighten the grub screws alternately with a torque wrench until the recommended torque value, listed in the product table, is achieved.

KMT and KMTA precision lock nuts should not be used to drive a bearing up onto a tapered seat.


KMT and KMTA lock nuts are adjustable. 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.

Adjustments can be made using the following procedure (fig. 4 and fig. 5):
  1. Loosen the grub screw(s) at the position showing the greatest deviation.
  2. Tighten the remaining screw(s) equally.
  3. Retighten the screw(s) that were loosened.
  4. Check that the alignment of the nut, relative to the shaft, is currently as required.
  5. Repeat the procedure if necessary.
When removing KMT and KMTA lock nuts, the locking pins can still engage the shaft thread even after the grub screws have been loosened. Using a rubber hammer, tap the nut lightly in the vicinity of the pins to loosen them.
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