Large-scale, bearing damage is less common today, thanks to improvements in design, education, and training. That said, the need to understand key causes of bearing damage—and how to prevent them—is no less urgent. Take care to adequately lubricate, guard against contamination, avoid overload, and properly handle and install bearings. In doing so, you protect these essential components from damage, increase throughput, prolong service life, and save time and money.
Inadequate lubrication is the most common cause of bearing failure. Below are three key checklist items on lubricating your Morbark horizontal grinder mill bearings*:

1. Repack bearings twice a year or every 1,000 hours, whichever comes first
2. Only use Morbark N3 mill-bearing grease
3. Only fill bottom half of bearing housing

*Note: The new, Morbark 3400XT has a new style bearing on the drive/belt side of the machine. This bearing requires grease every 40 hours. [The opposite side requires twice a year, or every 1,000 hours.]
Tip: Never pump grease into the center of the bearing housing, only onto the ends of the housing. This will grease the dust seal and keep contaminants out of the bearing. To do so, remove the cap from the mill bearings and remove all of the old grease from the housing. Check the clearance on the bearing, and adjust if necessary. Then, pump new, N3 grease into the bottom housing, filling it to the top of the lower housing, being careful not to overfill.
This is, by far, one of the most important maintenance items on your Morbark grinder. While failure is rare, neglect of this item can cause significant downtime, damage to adjacent components such as housings and shafts, costly repairs and potential injury should it fail. This maintenance procedure typically takes 3-4 hours to perform. You will then be ready for another 1,000 hours of safe, productive, trouble-free grinding. Why risk it?