Needle roller bearing components

Needle roller bearing inner rings
SKF supplies inner rings for needle roller bearings separately. They are typically combined with needle roller and cage assemblies or drawn cup needle roller bearings in applications where the shaft cannot be hardened and ground. Inner rings are available in the following two series:
  • IR series (fig. 1), with or without a lubrication hole, with or without a machining allowance
  • LR series (fig. 2)

Inner rings in both series are also available in different widths. Wide inner rings permit greater axial displacement of the shaft, relative to the housing, when compared to standard width inner rings. They also provide an excellent counterface for the lips of contact seals (fig. 3).

Regardless of whether the ring has an interference or loose fit, it should be located on both sides to prevent axial movement. One side can be located against a shoulder. The other side can be located by either a snap ring, a distance ring or a nut.

IR series

IR series inner rings (fig. 1), the standard SKF inner rings for needle roller bearings, are made of carbon chromium bearing steel. The rings are hardened and ground. The raceway surface is precision ground, and has a lead-in chamfer on both sides. The chamfers facilitate assembly and protect the seal lips from damage during the mounting process.

Some sizes of IR inner rings have a lubrication hole (fig. 4). They are identified by the designation suffix IS1. Inner rings with additional lubrication holes are available on request.

Also on request, SKF supplies inner rings in the IR series with a pre-ground raceway and a machining allowance z. These inner rings are identified by the designation suffix VGS. The machining allowance depends on the inner ring raceway diameter and is listed in table 1. They can be finish ground after mounting on a shaft in applications where extremely high running accuracy is required.

LR series

Inner rings in the LR series (fig. 2) are made of carbon chromium bearing steel. The rings are hardened, and the bore and raceway diameter are ground. The side faces are turned and the edges are smoothed. For applications where the larger run-out and width tolerances are less important, these inner rings can be used to provide a cost-effective bearing arrangement.

Needle rollers

SKF needle rollers are made of carbon chromium steel. The rollers have a hardness of 58 to 65 HRC and have a precision ground surface. They can be used to design full complement bearing arrangements for low-speed or oscillating applications. These compact bearing arrangements have a very high load carrying capacity when compared to bearings with a cage and are economical, provided the shaft and housing bore can serve as raceways (→ Raceways on shafts and in housings).

For assistance in designing full complement bearing arrangements or to calculate performance data for these bearing arrangements, contact the SKF application engineering service.

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