Closure

Protects the interior of the ball bearing against contamination and the components surrounding the ball bearing against escaping lubricant. The protection grade depends on the type of closure chosen and on the operating conditions. You will find more information on this in ‘Closures’.

Alignment

Mounting configuration where the axes of the two bearings are identical.

Retainer (Cage)

A ring with equally spaced ball pockets, which separates the balls from each other in the bearing raceway.

Combined Load

A force which is neither purely radial nor axial in nature, but simultaneously perpendicular and parallel to the axis.

Ball Pockets

The inner surfaces of a retainer which touch the ball surfaces.

Raceway Profile

The form of the raceway as seen in cross section.

Roundness

The roundness deviation is calculated by measuring the radius deviation using scanning equipment. You will find detailed information on this amongst other places in DIN ISO 4291 and DIN ISO 6318.

Curvature

The proportion of the radius of the raceway profile to the diameter of the ball.

Curvature [%] = 100 x radius of raceway profile 
                                     Ball diameter

Angular Contact Bearing, non-separable

(AC ball bearing) – Bearings with inner or outer ring lands relieved to facilitate snap-in assembly. This bearing, similar to a magneto bearing, can take axial loads in one direction only.

Angular Contact Bearing, separable

(L2T ball bearing) – Bearings with inner ring land relieved to facilitate removal of inner ring. The ball set is held in the outer ring by a special retainer. This bearing, similar to a magneto bearing, can take axial loads in one direction only.

Quality Grade

Term for the tolerances of a ball bearing. The individual tolerance values are defined in various standards such as DIN 620 T1, ISO 492, ISO 1224, AFBMA Std. 12 and 20. The definitions of the terms are defined among other places in DIN ISO 1132 and the measuring method in DIN 620 T1 and ISO TR 9274.

Full Complement Bearing

A bearing with a maximum number of balls. These bearings have no retainer. See ‘Retainer Types’ about the different types.