TM 9-6115-604-34NAVFAC P-8-633-34d. Inspect.(1)Support the crankshaft in V blocks and use a dial indicator to check full length alignment (A, Figure 9-39), shortbend alignment (B), and nose section and flywheel pilot runout (C).(2)If the TIR for full length alignment exceeds 0.002 inch (0.05 mm), straighten the crankshaft in accordance withstep e, below.(3)If the TIR between adjacent main bearing journals exceeds O.002 inch (0.005 mm) correct for short bendalignment in accordance with step e, below.(4)If the TIR of the nose section or flywheel pilot exceeds 0.001 inch (0.03 mm), correct the runout in accordancewith step e, below.(5)If the crankshaft gear was not removed, position the dial indicator on the gear teeth and check the runout. If theTIR exceeds 0.001 inch (0.03 mm), remove the gear in accordance with paragraph 9-18, and check the gear stepin accordance with step (6), below.(6)Visually inspect the gear step for physical damage, and measure the step size (A, Figure 9-40) and keyway width(B).(7)If the step size and keyway width are not in accordance with the dimensions given in Figure 9-40, the step shallbe chrome-plated and ground to size in accordance with step f, below.(8)Inspect the counterweight capscrew holes and pipe plug holes for damaged or stripped threads. The repair ofstripped threads shall be limited to three repairs per crankshaft. Repair stripped holes in accordance withparagraph 2-12.(9)Inspect the front and rear seal surfaces for grooving caused by the seal lip. If grooving exceeds 0.005 inch (0.13mm), install a wear sleeve in accordance with paragraph 9-28.(10)Using an outside micrometer, measure and record the connecting rod and main bearing journal diameters(Figure 9-41). Using these measurements, determine the feasibility of using the crankshaft as is, or grinding toone of the standard undersizes given in Figure 9-41. Grind the journals as necessary in accordance with step f,below.(11)If any journals show a blue or straw discoloration, heat damage may have occurred. Test these journals usingscleroscope hardness tester ST-1196. Crankshaft surface hardness should be 40 to 52 Rockwell, and corehardness is approximately 26 Rockwell. Make several tests in different areas of the suspected journal untilconsistent readings are obtained. If any area tests below 40 Rockwell, mark that journal for a trial grind andretest. In many cases heat damage is restricted to the surface and the crankshaft can be saved.(12)Inspect the crankshaft using fluorescent magnetic partide inspection in accordance with MIL-1-6868. Usemagnetic inspection unit MIL-M-6867, Type Ill, having a contact head opening of 96 inches (243.8 cm) and a 20inch (50.8 cm) coil. Mount the crankshaft between the contact heads and inspect as follows:(a)Apply at least three successive head shots of 1800 amperes for a duration of 1/2 second each.(b)Examine the crankshaft under black light for longitudinal cracks in accordance with A, Figure 9-42. Thelimits of acceptability shall be in accordance with Figure 9-43. Replace the crankshaft if it is defective.(c)Apply at least eight coil shots along the length of the crankshaft using 4500 to 5000 ampere turns.(d)Examine the crankshaft under black light for transverse cracks in accordance with B, Figure 9-42. Thelimits of acceptability shall be in accordance with Figure 943. Replace the crankshaft if it is defective.(e)If the crankshaft is acceptable, degauss it by activating the demagnetizing cycle before removing it fromthe inspection unit. Test for residual magnetism at several locations using a magnetic field indicator. Theresidual magnetism shall not exceed 3 oersteds (239 A/m).(13)If the crankshaft is to be returned to service at this point, dean it thoroughly in accordance with step c, above.9-76
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