Design Of Raceways
TIMKEN needle roller and cage radial assemblies use the housing bore as the outer raceway and the shaft as the inner raceway. In order to realize full bearing load rating and life the housing bore and the shaft raceways must have the correct geometric and metallurgical characteristics. The housing should be of sufficient cross section to maintain adequate roundness and running clearance under load. Additional design details for housings and shafts used as outer and inner raceway can be found in the engineering section of this catalog. The only limit to precision of the radial clearance of a mounted assembly is the capability of the user to hold close tolerances on the inner and outer raceways. The suggested shaft tolerances listed in Table 2 are based on housing bore tolerance G6 and apply to metric series radial needle roller and cage assemblies with needle rollers of group limits between P0M2 and M5M7.
Suggested Shaft Tolerances For Housing Bores Machined To G6
| Nominal shaft diameter in mm | ≤ 80 | > 80 |
|---|---|---|
| Radial clearance | Shaft tolerance | |
| smaller than normal | j5 | h5 |
| normal | h5 | g5 |
| larger than normal | g6 | f6 |
Axial Guidance Requirements
TIMKEN needle roller and cage radial assembly must be axially guided by shoulders or other suitable means. The end guiding surfaces should be hardened to minimize wear and must provide sufficient axial clearance to prevent end locking of the assembly. Length tolerance H11 is suggested.
If end guidance is provided by a housing shoulder at one end and by a shaft shoulder at the other end the shaft must be axially positioned to prevent end locking of needle roller and cage assembly. The housing and shaft shoulder heights should be 70 to 90 percent of the needle roller diameter to provide proper axial guidance.
Mounting In Sets
Needle roller and cage radial assemblies that are mounted side by side must have needle rollers of the same group limits to ensure uniform load distribution.
