NTNDeep Groove Ball Bearing Open 65x140x33 mm Heavy 6300 Series Pressed Steel Cage

Product Description

What this part is

This is a single row deep groove ball bearing measuring 65 mm bore by 140 mm outside diameter by 33 mm wide. It is open on both sides — no shields, no seals — with a pressed steel cage and standard CN radial internal clearance. There is no oil hole or lubrication groove in the outer ring. Deep groove ball bearings of this type carry radial load as their primary duty plus moderate axial load in either direction, and they are the highest-speed, lowest-friction rolling bearing type for a given envelope.

Decoding the designation

6313 splits into two meaningful parts. The 63 identifies a deep groove ball bearing in ISO dimension series 03, which is the heavy series. The 13 is the bore code, and bore codes in this range multiply by five: 13 × 5 = 65 mm bore. The designation carries no suffix, which identifies the bearing as open, normal tolerance class, and normal (CN) internal clearance.

The 6300 versus 6200 versus 6000 series distinction

This is the single most important thing to understand before ordering, because it is where buyers most often get it wrong. All three of those series use the same bore code system, so a 6013, a 6213 and a 6313 all have exactly the same 65 mm bore. They are not otherwise the same bearing. Each step up in series increases the outside diameter and the width, which means bigger balls, a deeper groove, and substantially more load capacity and shock tolerance.

Concretely: a 6213 is 65 x 120 x 23 mm. This 6313 is 65 x 140 x 33 mm. Both slide onto a 65 mm shaft. Neither fits the other’s housing bore — the outside diameters differ by 20 mm and the widths by 10 mm. Cross-shopping on bore diameter alone, or matching a number off a worn part where only the first digits are legible, produces the wrong bearing. The outside diameter of the bearing being replaced, or the housing bore, is the deciding measurement.

The reason the heavy series exists is capacity. The larger balls and deeper races of the 6300 series give it markedly higher dynamic and static ratings than the 6200 series at the same bore, which is why it turns up in electric motors under heavy belt load, gearboxes, pumps, crushers and drive shafts that take shock. The penalty is size, weight and a slightly lower speed limit than the lighter series.

Published ratings and mounting data

Bore diameter d: 65 mm. Outside diameter D: 140 mm. Width B: 33 mm. Number of rows: 1. Cage: pressed steel. Dynamic radial load rating Cr: 103 kN. Static radial load rating C0r: 60.0 kN. Limiting speed: 4,900 rpm with grease lubrication, 5,800 rpm with oil. Radial internal clearance: CN (normal). Closure: open, no shields or seals. Lubrication features: no oil hole, no oil groove. Operating temperature range: −40 to +120 °C. Mass: 2.080 kg.

What these specs mean in practice

The dynamic rating of 103 kN is the load at which the bearing achieves its nominal fatigue life under rotation, and it is the figure that feeds an L10 life calculation. The static rating of 60.0 kN is the different question of how much load the bearing can take at rest, or under momentary shock, before the balls permanently indent the raceways. On ball bearings the static figure is typically well below the dynamic figure — the opposite of what appears on full complement roller bearings — because a ball makes point contact and concentrates its load into a very small area. That is precisely why a heavily shock-loaded application often wants a roller bearing instead, and why a ball bearing rated 103 kN dynamically will not necessarily survive a 100 kN standing impact.

The two limiting speeds reflect lubrication method rather than the bearing itself. Grease has to be churned by the rolling elements and generates heat doing it, so 4,900 rpm is the practical ceiling on grease. Circulating oil carries heat away and permits 5,800 rpm. An application sitting near either number makes the lubrication decision part of the bearing decision.

The −40 to +120 °C range is the bearing steel and standard dimensional stabilisation limit, not a lubricant limit. Grease is almost always the narrower constraint in a hot application, so the grease specification governs whether the upper figure applies to a given installation.

Being open matters for sealing and relubrication

This bearing has no closures, which has two direct consequences. First, it depends entirely on the housing for contamination exclusion — there is no lip or shield keeping dirt and water out of the raceways. In a dirty or wet environment an open bearing needs a properly sealed housing or an external seal, or it will fail from contamination long before it fails from fatigue. Second, and more usefully, being open means grease can pass through it. Where the housing has a lubrication port, the bearing can be relubricated on a schedule and old grease purged, which extends service life considerably compared to a sealed-for-life bearing that gets one fill and no more.

For reference, NTN’s closure suffixes on this family are ZZ for metal shields on both sides, LLB and LLU for contact rubber seals, and NR for a snap ring groove in the outer ring. This bearing carries none of them. A shielded or sealed version, or a snap ring for axial location in a through-bored housing, is the suffixed part number rather than this bare open one.

Interchange guidance

6313 is an ISO-standard designation, so a 6313 from any major manufacturer shares the same 65 x 140 x 33 mm envelope. Search forms that reach this part include 6313, 6313C3 (increased clearance version), 6313ZZ and 6313LLU (shielded and sealed versions of the same size), and NTN 6313. The suffix and the clearance class should be verified against what the application actually requires — the size is standard, but the closure, clearance and cage are not.