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Lock nuts with integral locking device

Lock nuts with integral locking device

These lock nuts of the KMK design (fig 1) have an integral locking device, which takes the form of a pressure plate, the surface of which has a threaded profile. The pressure plate is pressed against the shaft thread by a grub screw, thus locking the nut in position (fig 2).

Mounting and dismounting are simple and the axial location effective and reliable. Neither additional locking washer nor keyway in the shaft is required. The KMK nuts can be re-used.

The KMK nuts have slots in the outside diameter so that they can be tightened using a hook spanner. A hexagonal wrench is needed to tighten the grub screw. Appropriate sizes of spanner and key are provided in the product table. Tighten the grub screw, until the recommended tightening torque quoted in the product table is obtained.


The dimensions and the thread of the KMK nuts are in accordance with ISO 2982-2:2001, except for the width. The grub screw corresponds to ISO 4026:1993, material class 45H.


The metric ISO thread is machined to tolerance 5H according to ISO 965-3:1998.

The maximum runout between the thread and the locating face is 0,02 mm.


SKF lock nuts in the KMK series are made of steel and are phosphated and protected by a solventless rust inhibitor.

Mating shaft threads

SKF recommends that the mating thread on the shaft to be made to 6g according to ISO 965-3:1998.

Bearing accessories | Adapter sleeves | Withdrawal sleeves | Lock nuts | Lock nuts with locking washer or clip | Lock nuts with locking screw | Lock nuts with integral locking device | Precision lock nuts with locking pins | Hydraulic nuts