NACHI NU203 NU Cylindrical Roller Bearing 17x40x12 mm

This NACHI range covers 23 single row cylindrical roller bearings in NU configuration (two flanges on the outer ring and none on the inner ring), with Normal (CN) radial internal clearance. Bores run from 17 to 85 mm (200 and 300 series; outer diameters 40 to 160 mm, widths 12 to 37 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 inner ring and roller set can be separated from the outer ring. 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

• NU configuration, with two flanges on the outer ring and none on the inner ring. The inner ring and roller set can be separated from the outer ring.
• No axial location: does not take axial load, used as a float (free) end bearing
• Normal (CN) radial internal clearance: 20 to 45 µm on a 17 mm bore up to 50 to 85 µm on a 85 mm bore
• Basic dynamic load rating Cr 12.6 to 190 kN and basic static load rating Cor 7.95 to 205 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 NU configuration has two flanges on the outer ring and none on the inner ring, so the inner ring and roller set can slide axially in the outer ring. That suits the float (free) end of a shaft, where it takes up thermal expansion, but it does not take axial load. If the bearing must locate the shaft axially, you need a type with a flange on both rings (see Related products).

These are Normal (CN) clearance bearings. If the inner ring will run hotter than the outer ring, the shaft deflects a lot, or the fits are tight, the C3 versions in the Related products section may suit better.

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.

If you are replacing a bearing, check the full number stamped on it, including any letters after the digits, and send AIMS the number or the dimensions if you are not sure.

Related products

More sizes in the same configuration: NACHI NU C3 cylindrical roller bearings (15 sizes). Other configurations: NACHI NJ cylindrical roller bearings (19 sizes) and NACHI N cylindrical roller bearings (25 sizes). For combined radial and axial loads on one bearing, see the NACHI tapered roller bearings (metric series).