| The needle roller bearings with retaining edge |
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| The retaining edge of heavy duty needle roller bearing is on the outer ring . It can be either fixed or spring lock ring. If the |
| center shaft tray is quenched and ground, the dismountable inner ring can be cancelled.Generally there are one row ne- |
| edle roller which includes NKI,NKIS,NA48,NA49 series needle roller bearings,NA69 series bearings.All those with aper- |
| ture diameter over32mmare doublerow needle roller bearings . There are oil groove or holes on the outer ring which |
| make needle roller bearing easy for lubricating. Only NKI series and the small sized NK19/16 , NK12/16 have neither oil |
| groove nor oil hole . NA49 series bearing have an oil hole on the inner ring. NA49 series needle roller bearings are either |
| one side sealed (RS) or double sides sealed (2RS). |
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| Needle roller bearings without retaining edge |
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| Needle roller bearings without retaining edge is NAO series which have got a smaller needle retainer assembly than the |
| bearing outer ring . Thus , the needle unit can move freely after the bearings are fitted . The axial guidance of the needle |
| unit requires a positioning face on the side. There is a oil groove , a oil hole and two rows of needles in the needle outer |
| ring of wide series, but no oil groove and oil hole in the narrow series which has only one row of bearing unit. |
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| Needle roller bearings without inner ring |
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| Needle roller bearings without inner ring includes NK , NKS ,RNA48 ,RNA49 RNA69 , RNA0 series. The rolling needles |
| roll directly on the quenched and ground shaft. The needle bearings without inner ring are compact in structure. The rot- |
| ating precision will be increased if the shaft is machined with high precision.For those needle bearings without retaining |
| edge or inner ring (RNAO), the outer ring and needle unit can not be exchanged. |
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| Single side and double side sealed needle roller bearings |
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| The sealed needle roller bearings are filled with lithium based grease.For more effective functioning of the sealing in axle |
| movement,there will be no guiding slope on the inner ring which is 1mm higher than outer ring. Ordinary sealed bearings |
| will operate in the temperature range of -30oC-20oC. |
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| Inner ring |
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| The inner ring of IR series is quenched and made with high precision.The dimensional tolerance and the geometric prec- |
| ision of thestandard grade inner ringis in compliancewith PO grade . In using needle roller bearings, the selection of |
| inner ring will enable the bearing to keep a normal operational backlash. |
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| Radical clearance and mounting |
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| Standard clearance of needle roller bearings is in CO group. For special requirements, clearance of C2, C3 AND C4 can |
| be supplied. When needle bearing is mounted in parallel, they should have the same radical clearances so that the load |
| can be distributed evenly. |
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| In general case,the mounting of the needle roller bearings needs compact combination so that the thin wall bush can be |
| well supported.The heavier the load is,the selection combination is bigger,especially when impact load should be consi- |
| dered.Furthermore,it is necessary to consider the combination of materials and temperature differences. |
