Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/957021
44 | March - April 2018 | www . machinerylubrication.com ere are some instances in which we have seen a sharp decline in the daily top-up of lube oil. What are the probable causes? Is crankcase ventilation pressure the culprit?" To understand the reduction in oil consumption, you must first determine where the oil is going. is will help diagnose the reason for the measured decline. Some degree of oil consumption is to be expected in all engines. What is considered normal or acceptable will vary based on the application and the design of the engine. Some engines consume oil by design from the very first time they are started. e consumption may be as much as one quart per 1,000 miles and yet still be considered acceptable. "What could cause a substantial reduction in the specific lubricating oil consumption (SLOC) value for a gas engine? "Which would be the best application of oil: an oil lifter (ring and collar) or oil circulation in a ventilator (large roller bearing with medium speed)?" Oil application methods vary based on a number of variables such as speed, size, lubricant viscosity and ambient conditions. You must match the lubricant delivery mechanism with how the machine is expected to operate. Otherwise, large amounts of wear can be generated, causing downtime and potentially excess energy consumption. It is important to understand the benef its and weaknesses of each method. Oil lifting devices are among the oldest lubricant delivery mechanisms. ey utilize the machine's rotational move- ment to pick up oil and transport it to the component that needs to be lubricated. e biggest difference between a ring oiler and a collar oiler is how it is affixed to the shaft. Ring oilers are not attached to the shaft but simply ride on it (sometimes in grooves) and lift the oil where it needs to go. Collar oilers are firmly attached to the shaft and rotate with it accord- ingly. Both ring oilers and collar oilers must operate at a defined shaft speed and be sized appropriately to lift the proper oil volume to lubricate the machine. While these devices are simple and generally require little main- tenance, there are some inherent drawbacks in their use. Perhaps the biggest potential problem involves insufficient oil levels. e oil level inside the machine must be contin- ually inspected to ensure the lifting device can function properly. An oil level that is slightly too high or too low can greatly impact the effective- ness of these devices. In cold conditions, there is also a risk of channeling, which means the lubricant viscosity is too high to be lifted. During startups and shut- downs, rings and collars may simply not lift enough oil to lubricate the machine. is can lead to boundary conditions and increased wear of the internal machine parts. Circulating oil systems are common for large, complex equip- ment, but they can be adapted to work on most oil-filled housings. Machines operating with circulating oil tend to run cooler. e lubricant also tends to last longer in these systems. Circulating oil systems typically have a larger volume of oil, and the additional piping and pumps allow you to better condition the oil with filters and heat exchangers built into the oil loop. Of course, there is added cost for these systems, and they must be monitored for leaks and to ensure the pump is working properly. If feasible, it would be best to go with a circulating system, as its bene- fits far outweigh the negatives. While this will cost more, you can better lubricate your machine if the circu- lating system is installed correctly. To help prolong the life of the machine and potentially the lubricant, be sure to include filtration in this type of system. Over time, this may pay for the upgrade of the system. ASK THE EXPERTS