Pillow block, flange, and stretcher unit take-up
NTN bearing units can be easily installed with a diversity of mounting methods, allowing full design performance to be achieved. When installing them, however, observe the following precautions to ensure that the bearings will work properly for their full design life.
- Bearing housing mounting face must be sufficiently rigid.
- Bearing housing mounting face must be as flat and smooth as possible (when placing the bearing housing on the frame, the housing must be stably seated without any excessive play) (Fig. 1). Flatness:Max. 0.1(0.05 is more useful.)
Installing a bearing housing to an uneven frame deforms the bearing housing, causing the bearing to become deformed too, possibly resulting in premature failure of the bearing.
- The tolerance of the angle between the bearing housing mounting face and the shaft should be ±2° max. (for narrower outer ring type, ±1° max.) for convenience of grease injection. For covered units, the tolerance should be ±1° max. (Fig. 2).
- The pillow block type and flange type bearing housings are provided with dowel-pin seats for correct positioning.
- Excessive tightening of the mouting bolts may cause the housing to deform. Tightening the bolts to the proper torque can avoid this issue. Also, NTN recommends using a washer with the bolt when mounting the housing as the bolt alone may cause damage to the housing.
Cartridge type bearing unit
For normal operating conditions, the cartridge type bearing housing fit must be H7. The housing bore must be finished so that the bearing unit can move freely in the axial direction.
Take-up type bearing unit
To install the take-up type bearing unit, fit the unit in the guide rail on a frame, and secure the inner ring of the bearing to the shaft. Then, install the adjusting bolt and nut, and lock the bearing unit with a tapered pin. Then finally, correctly position the bearing unit.
For dimensions and machining precision of the guide rail, adjusting bolt and nut, refer to the separate catalogue "Bearing Unit."