The term “groove” refers to a channel in the inner or outer ring of a rolling bearing or in the housing. This channel is used either to locate a snap ring or to lubricate the rolling bearing (often in conjunction with one or several lubrication holes). But how do the different types of groove differ from each other and what characteristics do they possess? In the following sections we describe the lubrication groove and the retaining groove by means of three examples and explain the purposes for which they are used.

Snap ring groove in deep-groove ball bearings

The snap ring groove in a single-row deep-groove ball bearing (suffix N, also referred to simply as ring groove or circumferential groove) is located on the outer ring of the bearing and can be used to locate a snap ring. This snap ring facilitates the axial fixation in the housing. The bearing thus operates with very low friction, achieves high rated speeds and is designed for low noise and vibration levels. This ensures that the bearing requires less maintenance effort. Furthermore, combined radial and axial loads can be supported in both directions. The version with the corresponding snap ring has the suffix NR.

Retaining grooves in four-point contact bearings

For the four-point contact bearing “QJ” the situation is somewhat different. Here, the retaining groove is again used to secure the bearing. In this case, however, two retaining grooves on opposite sides of the end face of the outer ring, i.e. offset by 180°, prevent the outer ring from rotating (suffix N2). This is achieved by securing the corresponding mating part at these positions during assembly. The bearing is thus designed to support a (large) axial load.

Lubrication groove and retaining groove in cylindrical roller bearings

For cylindrical roller bearings that are subject to large loads, a version is available with two retaining grooves and one lubrication groove in the outer ring. For bearings subject to high axial loading, a tight fit on the shaft and in the housing bore is not sufficient. For this reason, an additional attachment method, i.e. means of fixing the bearing, should be implemented, for example using retaining rings. Designations with the suffix 2NR indicate that the bearing has two retaining grooves and is supplied together with two loose retaining rings (WRE + dimensions, e.g. WRE280).
To guarantee a long service life during intensive use, these bearings also have a lubrication groove in the middle of the outer ring. In conjunction with the lubrication hole in the inner ring, the bearing can also be regularly relubricated during use, which contributes to the long service life of the cylindrical roller bearing.