Mounting a bearing in the NN 30 K series using a GB 30 series gauge

To mount a bearing in the NN 30 K series, SKF recommends using a GB 30 gauge, a bore gauge and the appropriate hydraulic tools to drive the bearing up onto its seat. Provisions for oil injection are useful for dismounting
(→ Provisions for mounting and dismounting). The typical mounting procedure comprises the following steps:
  1. Mounting the outer ring
    • Heat the housing to the appropriate temperature and slide the outer ring in position.
  2. Preparing the gauge
    • Let the housing and the outer ring cool to ambient temperature. Set a bore gauge to the raceway diameter and zero the indicator (fig.1).
    • Place the gauge in the centre of the gauging zone of the GB 30 gauge (fig.2). Adjust the GB 30 gauge, using the adjustment screw until the bore gauge indicates zero minus the correction value listed in the GB 30 user instructions.
    • Increase the inside diameter of the GB 30 gauge by the value of the desired preload or reduce the inside diameter by the value of the desired clearance, using the adjustment screw. Then set the GB 30 gauge indicator to zero. Keep this indicator setting unchanged during the mounting process.
  3. Mounting the inner ring (trial)
    • Coat the tapered shaft seat with a thin layer of light oil and push the inner ring, roller and cage assembly until the bearing bore makes good contact with its seat.
    • Expand the GB 30 gauge with the adjustment screw, place it over the roller set and release the adjustment screw so that the gauge makes contact with the roller set (fig.3).
    • Drive the inner ring roller and cage assembly together with the gauge further up on its seat until the indicator on the gauge reads zero. The inner ring is now in the correct position for the desired preload or clearance.
    • Expand the gauge using the adjustment screw and remove it from the roller and cage assembly.
  4. Mounting the inner ring (final)
    • Measure the distance between the bearing side face and the shaft abutment using gauge blocks (fig.4). Take measurements at different diametrical positions to check accuracy and misalignment. The difference between the single measurements should not exceed 3 to 4 μm.
    • Grind a pre-machined spacer ring to the measured width.
    • Remove the inner ring, mount the spacer ring, and drive up the inner ring again, until it firmly abuts the spacer ring.
    • Place the GB 30 gauge over the roller set as described earlier. Release the adjustment screw. If the indicator reads zero again, the inner ring is properly mounted. Remove the gauge and locate the inner ring, using a suitable locking device.
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