Aggregates Manager Digital Magazine
Issue link: https://read.dmtmag.com/i/113147
EQUIPMENT MANAGEMENT McLANAHAN POLYMERS– 1. Spider bushing clearance Failure to monitor or maintain proper spider bushing clearance is one of the most neglected maintenance areas. When spider bushing clearances are excessive, the lower journal (mainshaft) will have misalignment with the eccentric bushing, resulting in a crosscorner contact pattern and improper load distribution. This misalignment can lead to a catastrophic failure of the crusher. Spider bushing clearance should be checked every month, every 500 hours, or at every mantle change, whichever comes first. It is important to note that the spider bushing clearance must be measured at the fulcrum point of the spider bushing bore and while the mainshaft is at its working position. This assures that the most worn area of the mainshaft sleeve is aligned with the fulcrum point of the spider bushing bore. If clearances are found to be out-of-tolerance (excessive), the spider bushing, mainshaft sleeve, or both will need to be replaced. 2. Spider bushing lubrication level Another common maintenance mistake is the failure to maintain proper spider bushing lubricant level. The crusher mainshaft has both rotary and gyratory motion at slow speed and exerts fairly high pressures on both bearing surfaces, the mainshaft sleeve, and the spider bushing. A lubrication pool is used to lubricate these surfaces. The lubricant is retained in the bearing cavity by a spider bushing seal arrangement. It is important to understand that all spider bushing seals will leak a bit. Since ferrous metals are used in both the mainshaft sleeve and the spider bushing, the lubricant should contain an "extreme-pressure" additive. Proper spider bushing lubricant level is maintained at approximately 1.4 inches above the spider bushing flange. A low lubricant level will lead to rapid spider bushing wear, mainshaft sleeve wear, and, eventually, an eccentric bushing failure. The spider bushing lubricant level should be checked every day on a new crusher to determine the normal leakage trend. After a leakage trend has been established, check the lubricant level periodically to assure that the proper level is being maintained. 3. Balance cylinder nitrogen pressure Neglecting the balance cylinder is a somewhat common error. Irregularly shaped feed material, large chunks, or tramp in the crushing chamber of the gyratory crusher sometimes force the mainshaft upward in a quick "jumping" action. A single balance cylinder on some units, or multiple balance cylinders on others, is furnished to make the piston follow the mainshaft up when it is raised by jumping and eases the mainshaft down to its original Rugged Parts For Rugged Equipment! We Manufacture Our Screen Media & Wear Parts With Premium Open Cast Material! Modular & Trommel Screens – Customized For Your Equipment & Application – Replacements For Many Popular Systems – Tapered Openings Resist Plugging – Single & Dual Durometer Customized Urethane Wear Parts – Beaver Tails/Side Liners – Classifier Tank Parts – Trommel Wear Parts – Sand Valves & Seats – Cyclone Wear Parts – Classifier Shoes – Urethane Liner – Pipe Flange Seals – Pins & Bushings SEE US A BOOTH 13 T 35! E-mail: polymers@mclanahan.com mclanahan.com Text INFO to 205-289-3782 or visit www.aggman.com/info McLanahan_AGRM0313pg21.indd 1 AGGREGATES MANAGER March 2013 21 2/12/13 8:41