Spring Loaded Thrust Bearings

Spring Loaded Thrust Bearings

Question: Why are there minimum external down thrust requirements for motors built with spring loaded thrust bearings? What are these requirements?

Answer: Motors equipped with a spring loaded thrust bearing require a minimum external thrust load, sufficient to compress upper die springs and unload the lower guide bearing from the axial spring thrust. Refer to Table 5 for required minimum thrust values corresponding to bearing part numbers.

Table 5: Minimum Continuous External Down Thrust

Manufacturer’s Basic Bearing Number	Minimum Continuous External Downthrust
7226BCB	2000 LBS.
7320 BECBM	500 LBS.
7322 BEAMCB - QTY 2	4000 LBS.
29328 EJ	4000 LBS.
29330 EJ	6500 LBS.
29334 EJ	6000 LBS.
29338 EJ	6500 LBS.
29344 EJ	8000 LBS.
29422 EJ	4000 LBS. / 2 POLE
29422 EJ	2000 LBS. / 4 POLE & SLOWER
29426 EJ	3800 LBS.
29428 EJ	4500 LBS.
29430 EJ	4500 LBS.
29438 EJ	10500 LBS.

NOTE: Do not run motor with no load for more than fifteen minutes, as lower bearing damage may occur and improper seating of the thrust bearing may cause vibration.

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