Bearing Products for Hammermills and Grinders

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Hammermills and grinders have optimized modern grain processing. But these devices and their components need to be tough. Grain processing requires equipment that can run at high speeds, create heavy shock loads, operate in a heavily contaminated environment, and generate high temperatures. With all these factors in mind, it’s critical that the mounted spherical roller bearings are up to the task. If they’re not, equipment will fail, leading to downtime for the processing facility.  

When choosing mounted spherical roller bearings, you want to make sure your bearing has the optimal bearing seal, retainer material, clearance, and shaft locking type. These factors are critical to the performance and uptime of this equipment.  

Bearing Seals 

Hammermills and grinders generate a tremendous amount of fine dust and contaminants, which can destroy a bearing. This damage, however, can be minimized by choosing the correct seal. One challenge in choosing a seal that fights contamination ingression is that all seals are speed limited. Before any seal upgrade, you must ensure that the operating speed does not exceed the seal’s capabilities.  

The Rex™ line of bearings from Regal Rexnord offers several solutions to the contamination issue:  


The M-seal is a buna rubber, heavy-contact, spring-loaded lip seal. This seal is an outstanding performer against dry and wet contaminants. The rubber outside diameter seals up against the housing.  This works together with a heavy spring-loaded lip to provide a sealing solution that’s difficult to beat. Although it is speed limited, many of these applications operate at a safe speed for the M-seal. If the temperature exceeds 225°F, we can also supply the M-seal in Viton rubber, which is capable of 400°F.  


The K-Seal features a metal carrier with a molded, buna rubber light contact lip. The light contact lip generates less heat. It can be operated at a higher speed and is an ideal solution where the speed is too high for the M-seal.  

If your application speed exceeds the capabilities of the K or M-seal, we still have a solution. Rex offers bolt-on cast iron auxiliary caps. Combined with the standard clearance Z-seal, the bearing is capable of running at its max-rated RPM. Auxiliary caps offer a five-part sealing system, protecting the primary bearing seal. This provides the ultimate protection against contamination. The only limitation: you need extra length along the shaft to accommodate them. 

Bearing Retainers 

High shock applications can often challenge the capability of the bearing retainer or cage. The Rex™ standard cage material is engineered polymer, suited for most mounted roller bearing applications. If the shock is extreme, change to a steel retainer. Rex brand bearings offer a steel cage as an option. On the Link-Belt™ brand of roller bearings, steel is standard. 


Whether in high shock, high temperatures, or high speed, internal clearance is critical to the optimum performance for mounted roller bearings. The prominent feature of both Rex and Link-Belt roller bearings is that the bearing clearance is adjustable in the field and at the factory. Our Application Engineering team can specify the best bearing clearance for the application. We can increase clearance, for example, to reduce temperature and allow higher speeds. Reducing the operating temperature can be extremely important when operating in an explosive environment, a hazard in grain processing. It is also possible to reduce clearance to limit the effect of shock loading. With Rex and Link-Belt we can fine-tune the bearing clearance for the specific application. 

Shaft Locking Mechanism 

High shock and speed also challenge the capability of the shaft locking device. With setscrews continually working back and forth, you’ll see standard set collars can often coming loose in these applications. Over time, this action will cause the bearing to come loose on the shaft, resulting in a catastrophic failure. To virtually eliminate this failure mode, we recommend using a tapered adapter mount.  

Rex offers the premium 6000 series Shurlok Tapered adapter with easy on/easy off capability. The Shurlok utilizes a unique locknut and sleeve assembly. The assembly is threaded onto the inner ring of the bearing. This connection provides easy installation, as well as easy removal. The Shurlok, once installed per the service instructions, provides one of the most robust and reliable shaft locking mechanisms available. 

Shock, speed, contamination, and temperature create a hostile environment for mounted roller bearings. Choose wisely to make certain that your mounted bearing is configured for optimum performance in your operation’s grain-processing equipment. Remember, downtime is money. Contact us for more information 

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Mark Czubak

Mark Czubak is a Principal Engineer with the Rexnord Bearing business. He has spent nearly 40 years with Rexnord where he has managed all facets of engineering, including application, design and manufacturing, giving him a cradle to grave knowledge of mounted roller bearings. With this experience, Mark shares his passion and knowledge through bearing training, application assistance and installation. “Bearings are overlooked for the more expensive components of the system, but a bearing failure can cause just as much downtime as any other component so choose your bearings wisely, and save time and money.”