NSK 52208 Double-Direction Thrust Ball Bearing

A double-direction thrust ball bearing for reversing axial load on 30 mm shafts

The NSK 52208 is a double-direction thrust ball bearing of the 522 series. It has a 30 mm shaft washer bore, a 40 mm housing washer bore, a 68 mm outside diameter and a height of 36 mm. A thrust ball bearing is made of a washer with a raceway on each side of a central shaft washer, with a ball and cage set on either side, so axial load can be taken in both directions. NSK states that thrust ball bearings can sustain axial loads but no radial loads, so a radial bearing must carry the radial force and keep the shaft centred.

The single-direction 51208 on this site has the same 40 mm bore but takes axial load in one direction only; the 52208 is the choice where the load reverses or the shaft must be located axially both ways, for example on vertical pump shafts, machine tool tables, crane and swivel mechanisms, worm gear shafts and screw presses. The flat-seat version suits housings with an accurately machined support face; NSK also lists aligning-seat versions (54208) and aligning seat washer versions (54208 U) in the same table for housings where the face may be out of square.

Technical specifications

Neighbouring sizes in the 522 series

The rows come from the NSK catalogue table for double-direction thrust ball bearings with flat seat, covering the 20 to 35 mm shaft washer bore range around the 52208. Ca and C0a are the basic dynamic and static axial load ratings; the speeds are limiting speeds for grease and oil lubrication.

Selection, minimum load and installation

NSK advises applying some axial load to a thrust bearing to prevent slippage between the rolling elements and the raceways, and refers readers to its minimum load guidance. Without sufficient preload from the application, balls can skid, particularly at higher speed or with rapid acceleration; a light spring preload is common practice. The 52208 is limited to 2,600 r/min with grease and 3,800 r/min with oil, so it is a moderate speed bearing.

In mounting, the shaft washer must sit on the shaft with the interference fit chosen for the application, while the housing washers sit in the housing with clearance so they can centre on the balls. The central washer should abut a shoulder or spacer on the shaft; check the abutment dimensions in the table above or the NSK catalogue so the support faces cover the raceway. Order the correct seat type: the 52208 has flat seats, while 54208 and 54208 U need matching spherical seating surfaces. For radial support, a compact deep groove ball bearing such as the SKF 6206-2RS1 is a common partner. All ball bearings are grouped under Ball Bearings.

Related NSK products: NSK 51208 Thrust Ball Bearing, NSK 5206 Double-Row Angular Contact Ball Bearing, NSK QJ210 Four-Point-Contact Ball Bearing, NSK 7208A Single-Row Angular Contact Ball Bearing, NSK 6208DDU Deep Groove Ball Bearing and NSK 7304AWDT Matched Angular Contact Ball Bearings.

Documents and ordering

The attached PDF is a two-page extract from the NSK catalogue Rolling Bearings for Industrial Machinery (Cat. No. E1103b): the thrust ball bearing design and minimum axial load notes, and the double-direction table for bore diameter 10 to 55 mm. The photograph shows a 52205 bearing of the same type, because NSK publishes a series image rather than one image for each size. Send the designation 52208, the seat type you need and the quantity. Seven Star LLC is an independent supplier in Muscat; availability and lead time are confirmed per enquiry.