Lock nuts

SKF supplies lock nuts in a wide range of sizes; they are also referred to as shaft or withdrawal nuts, depending on their use. They are used to locate bearings and other components onto a shaft as well as to facilitate mounting bearings on tapered journals and dismounting bearings from withdrawal sleeves. SKF lock nuts offer five different ways of locking on the shaft, as described below.

Locking washer

Locking washers are simple, stable and reliable fastening elements. The washer engages a keyway in the shaft and locks the nut in position if one of the tabs is bent over into one of the slots around the circumference of the nuts. Locking washers are used with lock nuts in the KM and KML series as well as for the lock nuts with inch dimensions in the N and AN series (fig 1).

Locking clip or plate

Locking clips are attached to the nut using a bolt to engage a slot in the nut and a keyway in the shaft. Locking clips are used with lock nuts in the HM 30 and 31 series (fig 2).
Locking plates are attached to the nut using two bolts to engage in a keyway in the shaft. Locking plates are used with lock nuts with inch dimensions in the N 0(00) series (fig 3).

Locking screw

A small part of the nut thread is pressed into the shaft thread by a locking screw to prevent the nut from turning. Neither additional locking washer nor a keyway in the shaft is required. Lock nuts with locking screw (fig 4) are designated KMFE.

Locking device

A steel insert, an integral part of the nut thread, can be pressed against the shaft thread by a grub screw to prevent the nut from turning. Neither additional locking washer nor keyway in the shaft is required. Lock nuts with this kind of locking device (fig 5) are designated KMK.

Locking pins

Three locking pins are equally spaced around the circumference of the nut. The pins are arranged at the same angle as the thread flanks and can be pressed into the shaft thread by grub screws. The pins not only lock the nut but also accurately locate it at right angles to the shaft. No keyway in the shaft is required. Locking pins are used with the precision lock nuts in the KMT and KMTA series (fig 6).