For this NTN bearing, 20x52x15 mm and a weight of 0.151 kg apply; the specification table holds the further technical particulars. This variant features a contact seal and increased radial clearance (C3). A contact seal is itself a heat source, and it sits at the inner ring — the heat it introduces consumes clearance from the inside before any external heat source takes effect.
In a version sealed by contact on both sides an elastomeric lip bears against the inner ring and keeps moisture and fine dust away from the rolling chamber. The price for this is a frictional torque that is present independently of the load — and that torque becomes visible not only as lost power but first of all as heat at the place where it arises: at the contact face between lip and inner ring.
As a result the temperature difference that closes the clearance arises partly inside the bearing itself and not exclusively through an external heat source. To this share is added the interference fit on the shaft, which expands the inner ring, and in many applications the ambient heat of the drive as well. Increased clearance (C3) holds an allowance ready for this sum so that a residual clearance establishes itself in the warm running state at which the rolling contact does not run under constraint; if it turns out too small, the frictional torque rises further and the additional heat reduces the remaining clearance further still.
The grease charge is enclosed by the seals and dimensioned for the service life, which is why its ageing at the elevated operating temperature has to be assessed as well — it, rather than material fatigue, frequently limits the life at moderate load. In this version the permissible speed follows from the seal and not from the clearance class: a wider clearance does not raise the limit that the contact version sets.
Through-hardened standard bearing steel determines the temperature and load frame of the rings; the temperature limit of the sealing material is to be taken separately from the designation.
ManufacturerNTN
Bearing typeDeep-groove ball bearings
Bore d20 mm
Outer Ø D52 mm
Width B15 mm
Dyn. load C17.6 kN(Catalogue value, not verified)
Stat. load C₀7.9 kN(Catalogue value, not verified)
Limiting speed17,000 min⁻¹(Catalogue value, not verified)
Reference speed14,000 min⁻¹(Catalogue value, not verified)
Weight0.151 kg
Sealscontact seals on both sides
Clearanceradial internal clearance greater than normal
Cagepressed steel cage
Materialstandard bearing steel
Tolerancetolerance class P0/PN (ABEC 1)
Bore typecylindrical bore
€6.16/ pc
incl. VAT, plus shipping · price drops with quantity
In stock
Typically ready to ship in 1–2 days
In stock · ships via DPD, UPS or Deutsche Post
QtyUnit priceDisc.
1 – 4€6.16—
5 – 9€5.98−3 %
10 – 24€5.86−5 %
25 – 49€5.67−8 %
50 – 99€5.55−10 %
4 more for −3% volume discount
From 100 pcs: price and lead time on request – subject to review.
Total (1 pc)€6.16
NTN 6304 LLUC3/5K Kugellager (20x52x15)
— 20 x 52 x 15 mm
Response within 4 business hours
✓Free shipping over €100 · 14-day returns
✓Purchase on invoice – first order paid before dispatch, then 14-day terms for approved business customers
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.
