SKF 6309-Z/C4 Kugellager (45x100x25)

The dynamic load rating of 55.3 kN characterises this bearing. The static load rating is 31.5 kN. The limiting speed is 9500 rpm. This variant features greatly increased radial clearance (C4). The deep groove ball bearing is the most widely built rolling bearing type, and the reason is how little it asks: it carries radial load, supports moderate axial load in both directions, and demands little of the surrounding design.

The deep, closely conforming raceway grooves in the inner and outer ring capture the balls positively, so the bearing takes radial load and moderate axial load in both directions without a second bearing position to oppose it. Because the ball touches the raceway at a point, friction and heat stay low — the precondition for high speeds and for grease-for-life designs.

The limits follow from that same geometry: the small contact area caps load capacity against a roller bearing of equal size, and the bearing tolerates misalignment within narrow limits only, since angular error transfers straight into the raceway grooves. Seats in shaft and housing must therefore be aligned and geometrically accurate; where shaft deflection is expected, a self-aligning type belongs in that position.

The single shield runs without contact and holds back coarse contamination on its side; the open opposite side is left to the surrounding design, which seals it there or supplies the lubricant. Rings and rolling elements are made of through-hardened standard bearing steel. The strongly increased radial clearance is intended for pronounced temperature differences between the rings or for very tight fits; without those conditions the bearing runs with unnecessary play.

Heavily increased radial clearance C4 — Dimensional/form-fit equivalent — verify suffix-level details for critical applications. Matching suffixes are also listed by FAG (C4), NSK (C4), NTN (C4), NACHI (C4) and Timken (C4).