Article - The Black Bearing

15 February, 2016

Author - Sam Houston Regional Manager SA/NT

The Black Bearing
Author - Sam Houston Regional Manager SA/NT

The Black Bearing is a product developed by CBC in conjunction with NTN Corporation of Japan in order to provide a bearing with enhanced features and improved life for CBC customers in the broad-acre agriculture market.

The Black Bearing range stocked by CBC is the Wide Inner Ring (WIR) series. This particular series of single row ball bearings incorporates an eccentric collar lock. The WIR series in most cases features a spherical outside diameter which fits into a housing with a spherical seat to provide misalignment capability.

In developing the Black Bearing CBC undertook considerable research with end users (primarily farmers) via attendance to regional field days, trade nights and trade breakfasts. Some feedback regarding harvester bearing issues included:

  • The bearing runs dry of grease and is often mounted in a press metal housing without any provision for re-lubrication, which inevitably results in premature bearing failure as lubricant cannot be replenished, seals are damaged, and contaminants cannot be excluded.
  • Many users of broadacre agricultural harvesting equipment (headers) commented that the purchase cost of this machinery is now in excess of $500,000. It was therefore perceived that there was little value in not using the best parts and paying slightly more for a higher performance bearing to match the machine capability & performance made good sense.

A further consideration to the criticality of bearing performance on harvester applications was revealed at regional field days in discussions with local insurance assessors. These assessors confirmed claims have resulted from high value crop losses due to header fires caused by bearing failures.

Others commented that the issue of bearing failures where often compounded by the fact that the bearing corrodes and freezes on the shaft.

This not only makes replacement difficult but also more time consuming (often when the harvester is needed most). When a failure occurs in the process of harvesting the crop the farmer is understandably reluctant to use oxy acetylene equipment for fast removal of the frozen bearing anywhere near his crop.

This often means removal of components to a workshop environment as the least risky option to undertake the repair.

Finally many comments were also noted about harvester bearing failures due to ingress of contaminants. Wheat husks are abrasive and along with the moisture and dust in the operating environment these factors combine to rapidly break down standard bearing sealing arrangements.

CBC started negotiations with NTN Corporation Bearing Engineering Centreto produce a bearing that incorporates design features to overcome these issues and provide extended service life. These features are summarised as follows;

  1. The Black Bearing is black in colour because it undertakes a process where the inner and outer rings are coated with black oxide. While this gives the bearing improved corrosion and fretting resistance over normal high carbon bearing steel finishes. The major advantage is it provides a layer of oxide between the bearing inner ring and the shaft facilitating easy removal. This technology has been proven by NTN with agricultural OEM’s.
  2. The sealing on the bearing was the next area of attention and in this case it was decided to incorporate NTN’s “Trashguard” seal into the Black Bearing. This seal is again proven technology with agricultural OEM’s and features a heavy duty seal plate with a wide land seal lip to keep out contaminants. This seal design is also manufactured by the Timken Bearing Company (USA) formerly Fafnir Bearing Company for the same advantages in Agricultural applications.

This heavy duty “Trashguard” seal utilised in the Black Bearing design does result in some additional frictional drag. Therefore the limiting speed of the Black Bearing is approximately 50% lower than standard bearings. See Figure 1 below. The speed capability of the Black Bearing does exceed the requirement of the majority of agricultural applications.

CBC’s premium sealed range of Triple Lip Wide Inner Ring sealed bearings offers sealing capability in extreme environments however limiting speed capability is further reduced to approximately 20% of the standard bearings. 
Figure 1.
Shaft Diameter
Bearing NumberLimiting Speed RPM
 20 3/4JEL204D1V19
 25 1JEL205D1V19
 30 1-1/8
 40 1-1/2JEL208D1V19
 45 1-3/4JEL209D1V19
 - 1-15/16JEL210-115D1V19 1500
 - 2JEL211-200D1V19 1500

3. The Black Bearings design also incorporates a grease fill of 70% of the bearings internal free space. Bearings prepacked with grease normally have approximately 33% grease fill. This extra grease fill also impacts the Black Bearings limiting speed but adds the advantage of extended lubricant life. To further enhance lubricant life the grease specification is upgraded to a special synthetic formulation, Shell Stamina HDS. This superior duty grease provides excellent water resistance and longer life.

4. Other features incorporated into the Black Bearing include C3 radial clearance to accommodate heat expansion within the bearing and the inner ring eccentric shoulder is subject to a zone induction annealing process to make it tougher and resistant to cracking.

The Black Bearing has proven to be an outstanding success in delivering to our customers greater equipment reliability & extended service life. Although originally designed for broadacre agricultural applications the advantages it provides has seen it incorporated into other industries as varied as conveyors, fruit cleaning and packing machinery, sheep dipping machines, air conditioning fans and cotton processing. 

For further information on CBC’s products contact your local branch outlet or authorised CBC distributor.