All rotating equipment requires timely and effective lubrication to help reduce wear, minimize lubricant consumption, maximize efficiency, and curb unscheduled downtime. For concrete plants, the job can seem daunting. With potentially hundreds of lubrication points and harsh conditions, concrete plants (portable or stationary) face their fair share of lubrication challenges.
There is no shortage in the number and types of lubrication applications in the form of conveyor bearings, chain drives, drum mixer gears and bearings, electric motors, air compressors, fans and blowers, and many others. There also is no shortage of environmental influences, including temperature extremes, dirt, dust, and moisture. All make the case for proper lubrication.
In addition, cracks begin to surface with traditional “manual” lubrication methods. Over- or under-greasing of bearings, which lead to failure, always looms. Lubrication intervals may be sporadic or ill-timed. Contaminants can inadvertently be introduced, equipment reliability ultimately may be compromised, and, in some cases, points simply may be out-of-reach or otherwise impractical for maintenance staff to handle.
This has paved the way for centralized lubrication systems engineered to provide consistent lubricant in the right amount, at the right time, in the right way. Such systems in all their forms feed lubricant from a central source to the points on a machine or machining system where friction occurs.
With centralized lubrication, every bearing receives the proper lubricant in an exact amount to minimize wear and promote longer service life. The problems associated with excessive lubrication can vanish. Lubricant consumption can fall over time, in some applications by as much as 50% compared with inexact manual methods. Also, maintenance time, energy, and costs can diminish. The only requirements: Refill the lubrication reservoir and occasionally inspect the connected lubrication points.
Regardless of their configuration and scope, centralized lubrication systems can add value in concrete plants.System profiles
Centralized lubrication technology generally falls under two broad categories: total loss and circulating oil systems.
In total loss systems, friction points are always supplied with fresh lubricant (oil, fluid grease, or grease) at specific intervals (time or machine-cycle dependent) during the lubricating cycle, such as pump run time.
The lubricant is supplied in the proper quantity at friction points to allow for buildup of an adequate film of lubricant during the subsequent idle period. Over time, aging, evaporation, bleeding, and leaks will contribute to partial depletion of the lubricant at the friction point.
Circulating oil lubrication systems allow the lubricant to flow back into the lubricant reservoir for reuse after passing through the friction points. In this way, the lubricant carries even more benefits as it transfers forces and damps vibrations, removes abrasion particles from friction points, stabilizes the temperature of friction points, prevents corrosion, and removes condensation and process water.
Within the total loss and circulating oil categories, there are primary types of installations. These include single-line, dual-line, and progressive feeder lubrication systems.
- Single-Line: These total-loss lubrication systems supply machinery lubrication points with relatively small amounts of lubricant (oil or fluid grease up to NLGI grade 2) to cover precisely the amount consumed. As such, they operate intermittently. The lubricant can be delivered by manually, mechanically, hydraulically, or pneumatically operated piston pumps or by electrically driven gear pumps.
Piston distributors installed in the tubing system meter out the lubricant. Exchangeable metering nipples on the distributors make it possible to supply every lube point with the requisite amount of lubricant per stroke or pump work cycle. Metered quantities can range from 0.01 to 1.5 ccm per lubrication pulse and lube point. The lubrication pulses also can influence the amount of lubricant to be fed to the lube points.