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■Typesso that the rotational accuracy is improved. Also, the shaft rigidity can be improved as the shaft diameter Machined Type Needle Roller Bearings are available can be increased by an amount corresponding to the in various types shown in Table 1.inner ring thickness.Table 1.1 Type of bearing (Standard type)TypeCaged Needle Roller Guide Needle Roller BearingsBearingsCaged Needle Roller Bearings with Inner RingThis type of bearing is used when the shaft cannot be heat-treated and nished by grinding. The outer and inner rings are separable and a small relief clearance SeriesWithout inner ringWith inner ring(1)Without inner ringWith inner ring(1)is provided on both sides of the inner ring raceway to facilitate bearing mounting. In the TRI and BRI series, the width of the inner ring is larger than that of the outer ring.Due to heat expansion during operation or mounting errors, the inner or outer ring may be shifted axially and the whole length of the rollers may not be in con-tact with the raceway. Therefore, attention should be paid to the allowable axial shift S as shown in the table of dimensions.Needle Roller Bearings with SealThese bearings are sealed types of the NA49, NA69 and BRI series bearings, in which a seal is installed on one side (type with one seal) or both sides (type with two seals) of the bearing. The seal is made of special synthetic rubber and effectively prevents dust penetration and grease leakage.Guide Needle Roller BearingsThese bearings are full complement type bearings and use mallet-shaped rollers which are guided accu-rately by the guide rail located at the center of the outer ring raceway and the guide groove of the mallet-shaped roller. This minimizes skewing (tilting of the roller from its rotating axis), which is normally a weak point of full complement bearings, and improves the rotational accuracy. This type of bearing is especially suitable for heavy loads, shock loads and oscillating motions.Bearings with and without inner rings are available. In bearings with an inner ring, the width of the inner ring is larger than that of the outer ring.Dimension series 49RNA 49NA 49Dimension series 69RNA 69NA 69Dimension series 48RNA 48NA 48GTRGTRIFor heavy dutyFor light dutyInch seriesTRTAFBRTRITAFIBRI--Metric seriesTypeCaged Needle Roller Guide Needle Roller BearingsBearingsWithout inner ringWith inner ring(1)Without inner ringWith inner ring(1)Two side sealsRNA 49…UU NA 49…UU One side sealRNA 49…UNA 49…UTwo side sealsRNA 69…UUNA 69…UUOne side sealRNA 69…UNA 69…UTwo side sealsBR…UUBRI…UUOne side seal--------Dimension series 49Dimension series 69Metric seriesSeriesInch seriesTable 1.2 Type of bearing (With seal)Note(1) or Machined Type Needle Roller Bearings with the Needle Roller Bearings and Inner Rings, Inner Rings will be delivered separately. If product is needed as one unit, please contact IKO.Caged Needle Roller BearingsThis type of bearing combines a collared outer ring with the IKO's unique lightweight rigid cage and nee-dle rollers. During operation, needle rollers are guid-ed precisely by the cage, and an ideal load distribu-tion is obtained.The metric series consists of the NA48 and NA49 series of ISO Standard, NA69 and TAFI series which are based on the international dimension series, and the heavy duty TRI series which is widely used in Japan. The TAFI series has a sectional height as low as that of the shell type and is used for light loads.The inch series or BRI series is based on the speci-cations of ANSI Standard of USA.Caged Needle Roller Bearings without Inner Ring As shown in the section "Design of shaft and housing" on page A44, any desired radial clearance can be selected by assembling this type of bearing with a shaft which is heat-treated and nished by grinding.These bearings are free from the effects on dimen-sional accuracy caused by assembling an inner ring, D3
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