TM9-2815-202-34
4-33. PISTON AND CONNECTING ROD MAINTENANCE (CROSS-HEAD) (Cent)
(3) Connecting Rod
(a) Check connecting rod for visual damage. Scrap rod if it is bent, had previous bearing
l
failure. was overheated {blue) at to~ or bottom end, is fretted at split line between rod
and cap, or has excessive pound-in of bolt head or nut.
(b) Check for cracks by magnetic particle method.
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RODS WITH INDICATIONS OVER .DD5 DEEP
SECTION A-A
VIEW A
- A
/
=qg
WA
EXAMPLE OF A TRANSVERSE INDICATION
EXAMPLE OF AN INDICATION
THAT DOES NOT FOLLOW LONGITUDINAL
FOLLOWING
LONGITUDINAL
FORGING FLOW LINES CAN SE EITHER A
FORGING FLOW LINES.
FORGING LAP, HEAT TREAT CRACK, OR
START OF A FATIGUE CRACK.
*
VIEW A
~Not+.i3,T,cALAREA-+
CRITICAL AREA
ACCEPTABLE LIMITS
+
INDICATIONS IN NON-CRITICAL AREAS
ARE ACCEPTABLE UNLESS THEY CAN BE
OBSERVED AS OBVIOUS CRACKS
WITHOUT MAGNETIC INSPECTION.
LONGITUDINAL
INDICATIONS
TRANSVERSE INDICATIONS (ACROSS FLOW LINES).
GRINDING NOTES
FOLLOWING FORGED FLOW LINES ARE
HAVING A MAXIMUM LENGTH OF 1/2, WHICH CAN BE
uSUALLY SEAMS AND ARE NOT
CARE SHOULD BE TAKEN IN GRINDING
REMOVED BY GRINDING NO DEEPER THAN 1/64. ARE
CONSIDERED HARMFUL IF LESS THAN
oUT INDICATIONS TO ASSURE PROPER
ACCEPTABLE AFTER THEIR COMPLETE REMOVAL
1/32 DEEP DEPTH CAN BE DETERMINED
BLENDING OF GROUND AREA INTO
AN EXCEPTION TO THIS ISA ROD HAVING AN
BY GRINDING A SMALL AREA NEAR THE
UNGROUND SURFACE SO AS TO FORMA
INDICATION WHICH EXTENDS OVER THE EDGE OF W
CENTER OF THE INDICATION.
SM~TH CONTOUR.
SECTION AND IS PRESENT ON BOTH SIDES OF THE
FLANGE. IN THIS CASE, MAXIMUM ALLOWABLE
~~
DEPTH IS .005 (SEE SECTION A-A).
POOR PRACTICE
GOOD PRACTICE
(c) Inspect connecting rod bearing
bores for burrs or foreign
particles. Clean up minor burrs
with crocus cloth using circular
motion.
(d) If new connecting rod is required,
stamp cylinder number on
connecting rod (5) and cap (3).
(4) Connecting Rod Bearings
(a)
(b)
Inspect bearing shells for scoring,
pitting, flaking, etching, and dirt
grooving. If any of these defects
are present, discard bearing
shells.
Discard bearing shells with bright
spots on backs indicating
movement in bearing caps or
supports.
5
3
4-136
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