TM 9-6115-604-34NAVFAC P-8-633-34(31)Back the wheel out, and measure the journal with a micrometer to determine how much material must beremoved to attain the proper size. Set the feed indicator for this amount.(32)While keeping a careful check on the journal size, slowly feed the wheel in until the correct undersize hasbeen reached, and set the index on the feed indicator to 0. Let the grinding wheel dwell at this point untilspark-out occurs; this will improve surface finish and help prevent grinder bum damage.(33)Back the wheel out and traverse over to the other side of the journal. Feed the wheel in until it just touchesthe journal, and traverse over into the fillet area.(34)Feed the wheel in slowly until the feed indicator reaches 0, and spark-out has occurred. Back the wheelout and check the journal.(35)When checked with an outside micrometer, the journal shall be the correct undersize, and have nodetectable step at the point of wheel overlap.NOTEAlternate each main bearing journal as to which cut it made first If, on the first bearing journal,the right side was full width cut, then on the next journal make the full width cut on the leftside. The results in a more even breakdown of the grinding wheel and aids in producing agood surface finish on the reground journals.(36)Grind all other main bearing journals in accordance with steps (30) through (35) above.NOTEThe crankshaft thrust flange surfaces may be ground to an undersize of 0.010 inch (0.25 mm)or 0.020 inch (0.51 mm). Oversize thrust bearings are available for use with crankshafts whichhave had the thrust surfaces ground to these sizes. Grind each of the thrust surfaces to deanup grooving, abrasions, nicks, and wear. The front and rear thrust surfaces need not beground to the same standard size, but the crankshaft must be stamped to show the thrustsurface size. For uniform loading of the thrust bearing during engine operation, it isnecessary that the thrust surface be ground square with the centerline of the crankshaftwithin 0.002 inch (0.05 mm) TIR. Squareness of the thrust surfaces should be checked with adial indicator indexed near the outer edge of the thrust surface. If there is no damage (nicks,grooves, abrasion) to the thrust surface, up to 0.005 inch (0.13 mm) wear may be tolerated andconsidered as standard. If there is damage, then up to 0.005 inch (0.13 mm) may be removedand the thrust surface may be considered standard. If more than 0.005 inch (0.13 mm) wear ispresent or if more than 0.005 inch (0.13 mm) must be removed to properly dean up the thrustsurface, then it must be ground to accept oversize bearings of 0.010 inch (0.25 mm) or 0.020inch (0.51 mm). A maximum of 0.020 inch (0.51 mm) on each thrust surface may be removed(Figure 9-51).(37) Make a visual inspection of the thrust flange, and determine to what extent grinding must be done to dean up anywear or damage.NOTEIf the thrust flange is within wear limits, and scoring is not over 0.003 inch (0.08 mm) deep,restore the surfaces by polishing, or a very light grinding.(38)Determine the standard oversize that is needed on the front or rear thrust surface.WARNINGWhen grinding, do not traverse the grinding wheel Into the thrust surface. This will cause theside of the grinding wheel to break down, and may cause Injury to personnel, damage toequipment, or grinder bum.(39)Feed the wheel almost to the journal and then traverse it over until it just touches the thrust surface to beground. Then, back the wheel away from the journal until it dears the thrust surface.(40)Traverse the wheel over to make the desired cut. Leave approximately 0.001 to 0.002 inch (0.030 to 0.050mm) for a final cut. For example: if 0.009 inch (0.23 mm) must be removed from the surface, traverse thewheel over 0.007 inch (0.18 mm) and feed in slowly to make the cut. Back the wheel out and traverseover 0.002 inch (0.05 mm) to make the final cut. Feed the wheel in slowly when making the final cut, andallow the wheel to spark-out at the journal.9-92
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