NSK 634 DDMC3 (2RS) Kugellager (4x16x5)

At 4x16x5 mm and a unit weight of 0.005 kg, the installation envelope is fixed; further technical details are held in the specification table. This variant features a contact seal. Point contact between ball and raceway keeps frictional torque low, which is why this type runs faster and cooler than any other rolling bearing. 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 contact seal bears against its counterface and closes the rolling chamber against dust, splash water and wash-out; in return it raises frictional torque and limits permissible speed.

Rings and rolling elements are made of through-hardened standard bearing steel. The normal radial clearance recorded corresponds to the standard class and suits ordinary fits and temperature conditions.