The SKF 6311-2RS1/C3 is a single row deep groove ball bearing with a 55 mm bore, 120 mm outside diameter and 29 mm width, fitted with a contact rubber seal on both sides (2RS1) and C3 radial internal clearance. It belongs to the SKF Explorer performance class and, per SKF, carries a basic dynamic load rating of 74.1 kN and a basic static load rating of 45 kN.
The designation can be read directly: 6 = single row deep groove ball bearing, 3 = ISO dimension series 03 (medium), a heavier cross-section with larger balls for higher loads on the same shaft size; 11 = bore code for 55 mm (11 x 5); 2RS1 = contact seals on both sides; C3 = radial internal clearance greater than normal.
The contact seals rub lightly on the inner ring, which keeps grease in and dust, water and washdown spray out better than a shield. The price of that protection is speed: SKF lists a limiting speed of 3,800 r/min for this sealed version, against 6,300 r/min for the shielded 6311-2Z/C3.
Technical data
| SKF designation | 6311-2RS1/C3 |
|---|---|
| Bearing type | Single row deep groove ball bearing |
| Dimension series | 63 – ISO dimension series 03 (medium) |
| Bore diameter (d) | 55 mm |
| Outside diameter (D) | 120 mm |
| Width (B) | 29 mm |
| Basic dynamic load rating (C) | 74.1 kN |
| Basic static load rating (C0) | 45 kN |
| Reference speed | 12,000 r/min |
| Limiting speed | 3,800 r/min |
| SKF performance class | SKF Explorer |
| Sealing | Seal on both sides (contact) |
| Radial internal clearance | C3 (greater than normal) |
| Cage | Sheet metal (pressed steel) |
| Bore type | Cylindrical |
| Lubricant | Grease, no relubrication feature |
| Material | Bearing steel |
| Net weight | 1.38 kg |
| Condition | New, original SKF |
Typical applications
- Heavier electric motors and generators
- Idlers, pulleys and tensioners
- Agricultural and food-processing machinery that is washed down
- Textile, packaging and bottling machines
- Like-for-like replacement of a worn SKF 6311-2RS1/C3
Compatibility and replacement
Every 6311 bearing made to ISO 15 has the same 55 x 120 x 29 mm boundary dimensions, so this bearing fits wherever a 6311 with contact seals and C3 clearance from another maker was used. Suffixes differ between brands: shields are often marked ZZ or 2Z, contact seals 2RS, 2RS1, DDU or LLU, and the clearance C3 may appear as “C3” or “/C3”. Always match the sealing arrangement and the clearance class shown on the old bearing; if your machine needs the other closure, the 6311-2Z/C3 is the same size.
Frequently asked questions
What is the difference between 6311-2RS1/C3 and 6311-2Z/C3?
Only the closures. The 6311-2Z has non-contact steel shields; the 2RS1 version has contact rubber seals. Per SKF, the limiting speed is 6,300 r/min for 2Z and 3,800 r/min for 2RS1; the load ratings are the same. Choose shields for speed and low friction, seals for dirt and moisture.
Does the 6311-2RS1/C3 need greasing?
No. Per SKF it is supplied filled with grease and has no relubrication feature, so it is mounted as delivered and not washed out. Net weight per SKF is 1.38 kg.
What does C3 mean, and can I use a bearing without it?
C3 is a radial internal clearance greater than normal. It leaves room for the inner ring to expand with a tight shaft fit or with heat, which is why electric motors and hot-running machines often specify it. Fit the clearance class the machine maker specifies or that is marked on the old bearing; do not swap C3 for normal clearance without checking.
Related parts
- SKF 6311-2Z/C3 (shielded version)
- SKF 6310-2RS1/C3 (50 mm bore)
- SKF 6312-2RS1/C3 (60 mm bore)
- All SKF 6300 Series Bearings
Part of the SKF 6300 series stocked by RendatSP for electric motors, gearboxes, pumps, fans, conveyors and general industrial machinery, with fast shipping to Iraq, Saudi Arabia, UAE, Egypt, Yemen, Libya and across the Middle East and Africa.
Every part RendatSP supplies is new and original, carries a 1-year warranty and ships worldwide by air in 5 to 7 days once ready (shipping, payment and warranty). Send us the part number and quantity on WhatsApp or through the inquiry form and we will quote the same working day. Agents in Saudi Arabia, Iraq, the UAE, Egypt, Oman, Libya, Morocco, Mauritania, Yemen, Algeria and Jordan.
