September 26, 2003

By: Mark Harris
Website: http://www.bearing-n-bearings.com

Energy-intensive crushing requires a straight or tapered bore bearing equal to the task

As an energy-intensive exercise, crushing efficiently requires the interplay of a number of variables. If one or more of these variables are not functioning properly, costly failure modes may occur.

One of the most essential variables in energy-intensive crushing is the bearing. In crushing applications, self-aligning, anti-friction bearings are utilised. Due to the large bore and severe operating conditions, 231 or 232 series spherical roller bearings are usually used. The internal clearance for these types of bearings is usually at least one designation above normal clearance for that particular bearing (typically C3 or C4). These bearings can be either straight or tapered bore bearings. For ease of installation and removal, taper bore bearings with adapter sleeves can be used. Hydraulic removal features should be incorporated into the shaft or adapter design to aid in the installation and removal process. Sealing is extremely important in these types of applications, and there are a number of options to choose from. A simple axial labyrinth seal is one of the more common types of seals. For greater protection, a combination face rubbing seal (Triple Tect™) that is grease purge-able can be effective. Perhaps the best solution is the auxiliary taconite seal that offers an additional button-head grease fitting for seal purging. For further protection, "flingers" or "planar rings" throw off the larger materials while the grease purging "flushes" out the finer particles.

Another crucial component in the process is proper lubrication. Lubrication will depend greatly upon the application. Typical lubrication systems involve grease, static, or circulating oil. Synthetic grease or oil is also commonly used in these demanding applications. Extreme Pressure (EP) additives provide additional protection by separating rollers from raceways, and therefore help minimise bearing wear.

Without the proper interaction of the above variables, several typical crusher bearing failure modes can occur. These modes generally fall into three interactive categories: contamination, lubrication, and misalignment.

A bearing that has performed well in crusher duty applications is the DODGE® Europe HBND. It is constructed with a one-piece cast steel (GS 45) housing body with bolt-on end covers. The bearing is grease-lubricated through two buttonhead grease fittings, and features both adapter and direct mount options. The HBND also has self-aligning capabilities. Additional features include optional cast-closed end cover, reducing likelihood of contamination by 50%; axial labyrinth seal with positive contact V-Ring (Taconite option which provides additional grease fitting); and bore range from 50mm through 400mm, offering greater choice in sizes.

About The Author:

Mark Harris is a successful author and regular contributor to http://www.bearing-n-bearings.com.  Keep things running smoothly with ball bearings, roller bearings, ball thrust bearings and tapered bearings.