New bearing technology helps resolve age-old conveyor challenges.

While bulk conveyors routinely carry heavy loads for the aggregate industry, they can carry daunting operating challenges along the way, too. As an all-too familiar example, the ingress of dirt, sand, and grit at critical rolling bearing positions, historically, has caused production headaches when contaminants first damage bearing housing seals, then invade the bearings, and, ultimately, subject conveyor systems to unplanned shutdowns costing thousands of dollars and tons of time.

The problem can often be traced to the traditional use of unsealed, open-type bearings with standard housings and seals in a conveyor head and tail pulleys and take-up pulleys (among other locations). These types of bearings and housings offer little, if any, protection from abrasive contaminants, prompting some operations to respond by pumping large quantities of grease continuously into a bearing’s housing as a first line of defense. While this re-greasing may help, somewhat, in the short term, downsides can develop over the initial cost of lubricant and subsequent issues and costs associated with increased labor, need for constant lubricant disposal, and potentially adverse environmental impact.

An increasingly popular alternative is to operate unsealed, open-type bearings mounted in a split housing equipped with contact or auxiliary taconite seals. This offers improvement over minimally protected open bearings in standard housings, but space limitations may be a problem as taconite seals can be relatively costly and may increase the axial length of an assembly. These seals can also pose difficulties in achieving proper alignment.

The encouraging news is that leading manufacturers in the rolling bearing industry have continued to develop more advanced technologies to help keep conveyors up and running.

New generation of bearings

An entirely new generation of higher performance spherical roller bearings has injected new life into bearing reliability and service along the conveyor line. A combination of improved bearing material, unique bearing design, and upgraded manufacturing processes has helped to maximize the effect of lubrication and minimize the effects of wear and contamination, while reducing friction. The result: A proprietary performance class of spherical roller bearings providing higher load-carrying capacity and extended bearing service life.

A new generation of roller bearings has increased reliability along the conveyor line.

These are well suited for the rigors of conveyor applications in the aggregate industry due to an optimized design that benefits from refined internal geometry tolerances and improved surface structures. From the perspective of materials, the bearings are manufactured from high quality, clean, and homogenous bearing steel that undergoes a unique heat-treatment process, increasing the bearing’s wear resistance. The purity of the steel imparts the bearings with strength and durability, and the specialized heat treatment creates a combination of hardness and dimensional stability.

One key to improved performance is the redesigned internal geometry. Using proprietary software, engineers analyzed the interrelationship of the bearing’s rolling elements, raceways, and cage. Then, they devised methods to reduce friction, heat generation, and wear in the bearing, while increasing the ability to withstand heavier radial and/or axial loads.

The bearing’s rolling elements are manufactured to extremely close tolerances to reduce vibration levels and equalize load distribution. Cages are enhanced to improve guiding of the rolling elements and optimize the effect of the lubricant while lowering heat, friction, noise, and vibration levels. The surface topography of the bearing’s rolling elements and raceways enhances the formation of a hydrodynamic lubricant film, maximizing the effects of the lubricant, while reducing heat generation and wear. Ultimately, they minimize environmental impact by reducing lubricant and energy consumption.

Both during testing and in real-world applications, these bearings have been shown to run cooler, smoother, and longer than standard rolling bearings, particularly in heavy load slow-rotation applications, such as bulk conveyors.

Triple protection barrier

One of the technology developments engineered for conveyors — a three barrier solution — has introduced an environmentally friendly and cost-effective bundle of technologies to extend bearing service life and help prevent premature bearing failures without resorting to complicated auxiliary taconite seals and/or large quantities of grease.