Vanmark Corporation
Good Bearing Maintenance Lowers Costs

Proper bearing maintenance is one of the most important aspects of keeping equipment with rotating parts in good working order and minimizing downtime. It is a subject we get lots of inquires about. To understand the importance of good bearings, we first have to understand what they do. The primary functions of the bearings in a peeler are to support the load, keep the shafts aligned, and allow smooth rotation of the rolls. If any of these functions is compromised, it results in downtime and added operating costs.

It takes an excellent bearing to stand up to abuse inside a peeler running constantly for hours, sometimes days, on end. This is especially true of the bearings at the discharge end where the bearings are exposed to the harshest conditions. Vanmark uses a custom-designed bearing made especially for our Series 27, 2700 and 2800 peelers. These bearings are Timken tapered roller bearings capable of handling 2680 lbs of radial load and 1250 lbs of thrust load at a maximum speed of 4000 RPM. These bearings also provide true rolling motion with minimal friction. The inner race and rollers are made of case-hardened alloy steel to provide long service life under severe operating conditions.

Contamination is the bearing’s worst enemy. These bearings are protected by both internal and external seals to guard against contamination reaching the interior (see photo below). The internal seals (B) are actually inside the bearing and hidden from view.  The external seal (A) is a "face-riding" V-ring contact seal which rotates with the shaft. This rotation helps prevent contamination build-up by “flinging” debris away from the sealing area. The seal operates with less friction than radial “lip-type” seals, helping to reduce heat generation and wear. Standard bearings use labyrinth seals which may allow a direct channel for water to enter the bearing.

Contamination and water are the number one cause of bearing failure and can usually be traced to one of three things: (A) Improper lubrication, (B) Cleaning with high pressure sprays, or (C) Not installing new seals when the bearing is replaced.
Whether lubrication is done manually or automatically, we suggest the machine be properly greased and bearings checked immediately after each washdown to see that seals are tight against the face of the bearing. Both of these are important. Here is why.

Assume we have a typical machine which has been run for one or more shifts and is now shutdown for cleanup. During high pressure washdown and the bearings at the discharge end of the bed were inadvertently hit with this high pressure spray. A seal was dislodged by the spray and water has now accumulated on the bearing face. Cleanup is complete, but the bearings were not greased and the machine will sit for hours waiting for morning startup.

In normal operation, the bearing will run somewhat warmer than its surrounding environment and expands slights. At shutdown the metal bearing cools to room temperature and also shrinks. This normal contraction of the bearing acts like a siphon to draw the water and liquid contaminants sitting on the bearing face into the interior. The internal components now start to oxidize. This process can be accelerated when washdown water contains chlorine, since chlorine tends to enhance oxidation.

Greasing after washdown helps displace any water that may have been allowed to enter during cleanup. A simple visual inspection of the external seals after washdown, followed by proper greasing would have prevented the bearing’s contamination by washdown liquids and the next day’s operation. Preventative maintenance is always better than breakdown maintenance.

Don’t wait for the bearings to completely fail to let you know they need to be replaced. Routinely check for “play” or movement in your rolls and listen for unusual sounds during operation. Any amount of motion signals bearing wear.

When bearings are replaced we strongly recommend that external seals on both sides of the bearing be replaced as well. (see photo below)  Why use old seals with new bearings -- especially when new ones are provided free? When we hear some of our customers request that we not send seals “because we have a whole drawer full of them,” it tells us that there are a lot of new bearings out there being compromised by old seals and headed for premature failure. Vanmark supplies two external seals with every new bearing and we urge you to use them.

Although bearings do wear out, with proper installation and maintenance, bearing life can be extended dramatically and the extremely high cost of unscheduled downtime can be reduced or avoided.