NSK 5206 Double-Row Angular Contact Ball Bearing

Two angular contact rows in one bearing for thrust in both directions

The NSK 5206 is a double-row angular contact ball bearing with a 30 mm bore, 62 mm outside diameter and 23.8 mm width. NSK describes this design as essentially a back-to-back mounting of two single-row angular contact bearings whose inner and outer rings are each made as one piece. It can therefore sustain axial loads in both directions and has good capacity for moment loads, and it is often used as the fixed-end bearing in a shaft arrangement. The cage is pressed steel. Compared with a pair of single-row bearings the 5206 is shorter to install and needs no matching, which suits pump shafts, gearbox input shafts, blowers and compressor drives where one bearing must locate the shaft.

Technical specifications

Size table for the NSK 52 series

Rows are open-type double-row bearings from the NSK angular contact bearing table. Shielded (ZZ) and sealed (DDU) versions carry slightly lower ratings, as shown for the 5206 above.

Designation and selection

In the NSK designation the first digit 5 means a double-row angular contact bearing, the next is the dimension series (2 for the 02 series, 3 for the 03 series) and then the bore number. Suffixes ZZ and DDU mean a steel shield or a rubber contact seal on both sides, V and VV a non-contact seal, and a grease code such as NS7 is required when shields or seals are fitted on both sides. The sealed versions in the NSK table are listed as 5206BZZ and 5206BDDU. NSK says to consult it on the clearance of double-row bearings, so state the clearance class and application when enquiring.

The 52 series is not intended for very light loads: some axial or radial load should always be present so the balls roll rather than slide. Where only radial load is present a deep groove bearing such as the SKF 6206-2RS1 is usually sufficient; more bearings are listed under Electric Motors, Pumps and Turbines.

Documents and ordering

Confirm bore, seal type, clearance class, speed, shaft and housing fits and the loads in both axial directions. The attached PDF is a page extract from NSK catalogue Rolling Bearings for Industrial Machinery (Cat. No. E1103b) with the double-row design notes and bearing tables. Seven Star LLC is an independent supplier in Muscat; availability and lead time are confirmed per enquiry.

How the NSK 5206 bearing works

A ball bearing lets a shaft turn inside a housing with low friction while it carries load. In an angular contact bearing the contact line between the balls and the raceways is tilted, so the bearing can carry a combination of radial and axial load. The 5206 has two rows of balls in one set of rings, which is the same as two single-row angular contact bearings mounted back to back. Because of this, the bearing carries axial load in both directions and resists tilting moments, and one bearing is enough to locate a shaft axially. The 5206 has a bore of 30 mm, an outside diameter of 62 mm and a width of 23.8 mm.

Where the 5206 is used

• Pump shafts that need an axial locating bearing.
• Gearbox input shafts.
• Blowers and fans.
• Compressor drives.
• Fixed-end positions in shaft arrangements with a floating bearing at the other end.

Selection checklist for the 5206

• Bore of 30 mm, outside diameter of 62 mm and width of 23.8 mm.
• Open, shielded (5206BZZ) or contact-sealed (5206BDDU) version.
• Basic dynamic load rating of 32,500 N and static rating of 21,100 N for the open type.
• Limiting speed of 7,100 rpm with grease and 9,500 rpm with oil, for the open type.
• Axial load in both directions and the moment load.
• Pressed steel cage.
• Load centre spacing of 31.6 mm for the moment calculation.
• Chamfer of 1 mm minimum, so the shaft and housing shoulders must match.
• Mass of about 0.30 kg.

Installation, commissioning and maintenance notes

Keep the bearing clean until it is fitted, and mount it with a tool that presses on the ring being fitted, never through the balls. Check the shaft and housing seats for size and roundness, and make sure the shoulders clear the chamfer of 1 mm. Use the grease type and quantity suited to the speed, and run the machine and watch the temperature and noise during the first hours. Open bearings need lubrication planning, while the sealed versions are lubricated for life within their limits. Record the designation and the date of fitting in the maintenance log.

Requesting a quotation for the NSK 5206

Send the designation, the version (open, ZZ or DDU) and the quantity. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.

Sealed versions of the 5206

The shielded 5206BZZ and the contact-sealed 5206BDDU have a dynamic rating of 27,800 N and a static rating of 18,200 N. Their grease limiting speeds are 7,100 rpm (ZZ) and 6,300 rpm (DDU).

Equivalent load

For Fa/Fr up to 0.68 the dynamic factors are X = 1 and Y = 0.92. Above that ratio X = 0.67 and Y = 1.41, and the static equivalent load is P0 = Fr + 0.76 Fa.

Compared with two single-row bearings

The double-row design is shorter to install than a pair of single-row bearings and needs no matching of the pair.

Bearing records

Record the designation, the version and the position of each bearing on the machine.