Effigy three-28.—Checking the alignment of a connecting rod. REPAIRING CRANKSHAFTS AND JOURNAL BEARINGS The repair of crankshafts and bearings varies depending on the extent of impairment. There is no dubiousness about the necessity for replacing such items every bit cleaved or bent crankshafts. Out-of-round journals may exist reground and undersize begetting shells may be installed, merely this requires personnel skilled in the employ of precision tools. If a new shaft is available, it should be installed and the damaged shaft should be sent to a salvage reclamation middle. Nether certain conditions, scored crankshaft journals or damaged journal bearings may be kept in service if proper repair is performed. Repair of SCORED JOURNALS depends on the extent of scoring. If a crankshaft has been overheated, the effect of the original heat treatment will take been destroyed. In this case, the crankshaft should be replaced. If journal scoring is only slight, yous can employ an oilstone for dressing purposes if you lot take precautionary measures with respect to abrasives during the procedure. During the dressing operation, plug all oil passages within the journal and those connecting the mainbearing journal and the next connecting rod journal. In the dressing procedure, use a fine oilstone, followed with crocus cloth, to polish the surface. Later on dressing journals, always launder them with diesel oil. This procedure must include washing the internal oil passages too equally the outside periodical surfaces. Some passages are large plenty to accommodate a cleaning brush; smaller passages can be cleaned by bravado them out with compressed air. E'er dry out the passages by blowing compressed air through them. NEVER STOW A CRANKSHAFT OR BEARING PART ON Any METAL SURFACE. When you remove a shaft from an engine, place it on a wooden plank with Figure iii-29.—Using a strain or deflection gauge betwixt crank webs. all journal surfaces protected. If the shaft is to be exposed for some time, protect each periodical surface with a coating of heavy grease. Ever place bearings on wooden boards or clean cloths. CRANKSHAFT overhaul consists of an inspection, servicing for scoring and vesture, and a determination of each crank spider web deflection. Accept crank web deflection readings according to the Planned Maintenance System (PMS). A strain gauge, oft called a crank web deflection indicator, is used to take deflection readings. The gauge is only a dial-reading inside micrometer used to measure the variation in the distance between side by side crank webs as the engine shaft is barred over. Figure 3-29 shows a strain estimate between crank webs. When you lot install the guess, or indicator, betwixt the webs of a crank throw, exist sure to identify the gauge as far as possible from the centrality of the connecting rod journal. Residuum the ends of the indicator in prick-punch marks in the crank webs. If these marks are not present, make them and so that the indicator can exist placed in its correct position. Consult the manufacturer's technical transmission for the proper location of new marks. Readings are generally taken at the four crank positions: top dead middle, inboard, well-nigh or at bottom dead center, and outboard. In some engines, it is possible to take readings at bottom dead eye. In others, the connecting rod may interfere, making it necessary to take the reading equally near as possible to bottom expressionless center without having the estimate come in contact with the connecting rod. When the gauge is in its lowest 3-19
Source: http://enginemechanics.tpub.com/14076/css/Repairing-Crankshafts-And-Journal-Bearings-71.htm
Posted by: lunasearly1971.blogspot.com
0 Response to "Can A Damaged Rod Journal Be Repaired On A Crankshaft?"
Post a Comment