The dynamic load rating of 47 kN characterises this bearing. The static load rating is 25 kN. This variant features a contact seal and increased radial clearance (C3). The heat balance of this version is asymmetric: on one side the lip introduces frictional heat, on the other the lubricant can carry it back out. In this combination sealing and clearance class are linked through temperature, but not in the same way as in a doubly closed version.
The contact seal on one side lays an elastomeric lip against the inner ring and keeps moisture and fine dust out of the rolling chamber; in doing so it produces a load-independent frictional torque whose heat arises directly at the inner ring and thus warms the very ring whose expansion closes the clearance. The open opposite side counteracts this warming, because lubricant from the surrounding space can reach the rolling contact and carry frictional heat away with it; how large that contribution turns out depends on the assembly and not on the bearing alone.
Increased clearance (C3) holds an allowance ready for the remaining sum of interference fit, seal friction and external heat flow, so that a residual clearance establishes itself in the warm running state at which the rolling contact is not preloaded. If it is set too small, frictional torque and temperature rise further and reduce the remaining clearance additionally; if it is set too wide, the load zone narrows and, at low radial load, the load-free part of the ball set can slide.
The asymmetry also implies a mounting instruction: the seal faces the loaded side, the open side the interior supplied with lubricant, and this assignment is to be recorded because it is not recognisable during assembly. The permissible speed follows from the contact version and not from the clearance class. Through-hardened standard bearing steel sets the frame for hardness and dimensional accuracy of the rings; the temperature limit of the sealing material is to be taken separately from the designation.
Increased radial clearance C3 — Dimensional/form-fit equivalent — verify suffix-level details for critical applications. Matching suffixes are also listed by SKF (HC5C3, HC5C3WT, C3), NSK (C3), NTN (C3) and NACHI (C3).
ManufacturerFAG
Bearing typeDeep-groove ball bearings
Bore d40 mm
Outer Ø D90 mm
Width B23 mm
Dyn. load C47 kN
Stat. load C₀25 kN
Weight0.618 kg
Sealscontact seal on one side
Clearanceradial internal clearance greater than normal
Cagepressed steel cage
Materialstandard bearing steel
Tolerancetolerance class P0/PN (ABEC 1)
Shaft shoulder dₐ49–56.1 mm
Housing shoulder Dₐ73.8–81 mm
Bore typecylindrical bore
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FAG 6308-RSR-C3 Kugellager (40x90x23)
— 40 x 90 x 23 mm
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Same dimensions means the same bearing type and matching main dimensions (d × D × B). Sealing, cage, internal clearance and execution (e.g. material, precision, grease fill) are encoded in the suffix and may differ — please check before ordering. Equivalent additionally means the same sealing, internal clearance and tolerance class; the cage and other suffix features (e.g. lubrication groove) may differ.
