NACHI N311C3 N Cylindrical Roller Bearing 55x120x29 mm, C3

This NACHI range covers 8 single row cylindrical roller bearings in N configuration (two flanges on the inner ring and none on the outer ring), with C3 radial internal clearance. Bores run from 25 to 85 mm (200 and 300 series; outer diameters 62 to 180 mm, widths 17 to 41 mm). Select the size from the drop-down: each size has its own bearing number, load ratings and limiting speeds in the Model Details.

The outer ring can be separated from the inner ring and roller set. It does not take axial load and is used as a float (free) end bearing. Cylindrical roller bearings have line contact between rollers and raceways, which gives a high radial load capacity for the size.

Where this product is used

• Electric motors and generators
• Gearboxes and industrial transmissions
• Pumps, fans and compressors
• Machine tools and general industrial machinery
• Conveyor drives and other heavy rotating equipment

Features

• N configuration, with two flanges on the inner ring and none on the outer ring. The outer ring can be separated from the inner ring and roller set.
• No axial location: does not take axial load, used as a float (free) end bearing
• C3 radial internal clearance, larger than Normal: 35 to 60 µm on a 25 mm bore up to 75 to 110 µm on a 85 mm bore
• Basic dynamic load rating Cr 29.3 to 224 kN and basic static load rating Cor 25.2 to 247 kN across the range; load ratings, speeds and dimensions for every size come from the manufacturer’s catalogue

Key specifications

Available sizes

Limiting speeds are the catalogue table values for machined-cage bearings; for a pressed steel cage (the catalogue standard cage for these sizes) multiply by 0.8.

Selecting the right option

The N configuration has two flanges on the inner ring and none on the outer ring, so the outer ring can slide axially over the roller set. That suits the float (free) end of a shaft, where it takes up thermal expansion, but it does not take axial load. Because the rings separate, each can be given an interference fit when both need one. If the bearing must locate the shaft axially, you need a type with a flange on both rings (see Related products).

C3 radial internal clearance is larger than Normal. The catalogue recommends C3 or larger where the inner ring runs hotter than the outer ring or the shaft deflects a lot. Interference fits also reduce the working clearance, so check it for your fits and operating temperatures.

Both 200 and 300 series bearings are listed. For the same bore the 300 series has a larger outer diameter and width and a higher load rating than the 200 series, so choose on the housing space you have and the load to be carried.

Fitting and use

Check the load and speed against the catalogue figures before ordering and apply a suitable safety factor. Cylindrical roller bearings are mainly for radial load: any axial load must be well within what the flanges can carry by sliding contact, and the limit depends on lubrication and speed as well as the bearing.

The catalogue limiting speeds are for machined-cage bearings; for a pressed steel cage multiply them by 0.8. Pressed steel is the catalogue standard cage for these sizes, so the Model Details show both figures for each size.

These bearings are open: the housing arrangement has to supply and hold the lubricant and keep contamination out. Fit the rings with the housing and shaft tolerances recommended for your application, and keep the shaft and housing seats clean and square.

Related products

More sizes in the same configuration: NACHI N cylindrical roller bearings (25 sizes). Other configurations: NACHI NU C3 cylindrical roller bearings (15 sizes) and NACHI NJ C3 cylindrical roller bearings (12 sizes). For combined radial and axial loads on one bearing, see the NACHI tapered roller bearings (metric series).