WHAT ARE THE REASONS WHY CONNECTING ROD BOLTS ARE PRONE TO BREAKAGE IN OUR FASTENER INDUSTRY? TODAY, LET'S LIST THEM OUT.THE DIESEL ENGINE SERIES IS HIGHLY REINFORCED, AND THE CONNECTING ROD IS SUBJECTED TO GREATER IMPACT LOADS, MUCH LARGER THAN ORDINARY DIESEL ENGINES. THE REPEATED USE OF CONNECTING ROD BOLTS CAN EASILY LEAD TO BREAKAGE, DAMAGE TO THE ENGINE CYLINDER BLOCK, AND RESULT IN ENGINE SCRAPPING. ALTHOUGH SOME UNITS HAVE REPLACED THE CONNECTING ROD BOLTS, THERE HAVE ALSO BEEN FRACTURE FAULTS, AND A FEW ENGINES HAVE EXPERIENCED SUDDEN BREAKAGE OF THE CONNECTING ROD BOLTS DURING OPERATION.THE CONNECTING ROD BOLTS OF DIESEL ENGINES ARE DISPOSABLE AND ARE NOT ALLOWED TO BE REUSED. IF THE CONNECTING ROD BOLTS ARE REUSED, DUE TO THE HIGH STRESS, THE BOLTS WILL ELONGATE, WHICH CAN EASILY CAUSE THE BEARING TO ROLL AND BURN DUE TO INSUFFICIENT TIGHTENING FORCE OF THE BOLTS. AT THE SAME TIME, DUE TO INSUFFICIENT FASTENING FORCE, THE CLEARANCE BETWEEN THE BEARING AND THE CRANKSHAFT JOURNAL INCREASES, RESULTING IN LOW OIL PRESSURE AND EXCESSIVE WEAR OF THE BEARING, LEADING TO BEARING BURNOUT ACCIDENTS.PREVENTIVE MEASURES:① DURING THE SECOND LEVEL MAINTENANCE OF THE 12000KM RUN, THE ENGINE OIL PAN SHOULD BE REMOVED AND THE USE OF THE ENGINE BEARING SHELLS SHOULD BE CHECKED. IF INDIVIDUAL BEARING SHELLS HAVE EXCESSIVE CLEARANCE, THEY SHOULD BE REPLACED. AT THE SAME TIME, THE CONNECTING ROD BOLTS SHOULD ALSO BE REPLACED. IF THE ENGINE RUNS UNEVENLY OR MAKES ABNORMAL NOISES DURING NORMAL OPERATION, IT SHOULD BE STOPPED AND CHECKED IN A TIMELY MANNER.② DURING EACH MAINTENANCE, THE NEWLY REPLACED CONNECTING ROD BOLTS SHOULD BE INSPECTED, PAYING ATTENTION TO WHETHER THERE ARE CRACKS OR DENTS IN THE HEAD, GUIDE PART, AND THREAD OF THE BOLTS, AND WHETHER THE TOOTH SHAPE AND PITCH OF THE THREADS ARE ABNORMAL. IF THERE ARE ANY ABNORMAL SITUATIONS, THEY SHOULD BE AVOIDED.③ WHEN ASSEMBLING THE CONNECTING ROD CAP, USE A TORQUE WRENCH TO TIGHTEN IT ACCORDING TO THE SPECIFIED STANDARDS TO PREVENT EXCESSIVE OR INSUFFICIENT TORQUE.④ SELECT CONNECTING ROD BOLTS PRODUCED BY SUPPORTING FACTORIES.ANALYSIS OF THE CAUSE OF THE MALFUNCTION:① EXCESSIVE TIGHTENING TORQUE AND UNEVEN FORCE DURING ASSEMBLY. DUE TO THE LACK OF STRICT USE OF TORQUE WRENCHES DURING ASSEMBLY AND A LACK OF UNDERSTANDING OF THE SPECIFIC TIGHTENING TORQUE, IT IS BELIEVED THAT THE TIGHTER THE TORQUE, THE BETTER; A LONGER FORCE ROD IS USED TO TIGHTEN THE CONNECTING ROD BOLTS, AND THE TIGHTENING TORQUE IS TOO HIGH, EXCEEDING THE YIELD LIMIT OF THE BOLT MATERIAL, CAUSING THE CONNECTING ROD BOLTS TO YIELD AND DEFORM, RESULTING IN EXCESSIVE ELONGATION AND FRACTURE UNDER IMPACT LOADS. IT SHOULD BE EMPHASIZED THAT THE CONNECTING ROD BOLTS MUST BE TIGHTENED ACCORDING TO THE STANDARD, AND IT MUST NOT BE ASSUMED THAT THE TIGHTER AND STRONGER THE FORCE, THE BETTER.② THE CONNECTING RODS OF DIESEL ENGINES ARE DIVIDED INTO MULTIPLE LEVELS, AND ATTENTION SHOULD BE PAID TO NOT USING DIFFERENT LEVELS OF CONNECTING RODS DURING MAINTENANCE. IF THE CONNECTING ROD CAP IS MESSED UP OR INSTALLED INCORRECTLY DUE TO CARELESSNESS DURING MAINTENANCE, IT WILL RESULT IN A LOOSE FIT OF THE CONNECTING ROD BIG END JOINT SURFACE, WHICH WILL CAUSE THE CONNECTING ROD CAP TO LOOSEN AND LEAD TO THE FRACTURE OF THE CONNECTING ROD BOLT DURING ENGINE OPERATION. THE CONNECTING ROD BIG END OF WD615 SERIES DIESEL ENGINES IS OF A BEVELED MOUTH TYPE, WITH A BEVELED ANGLE OF 45 °. THE JOINT SURFACE BETWEEN THE CONNECTING ROD CAP AND THE CONNECTING ROD BIG END ADOPTS A 60 ° SERRATED POSITIONING STRUCTURE, WHICH HAS THE CHARACTERISTICS OF TIGHT FITTING, ACCURATE POSITIONING, RELIABILITY, AND COMPACT STRUCTURE. IF THE CONNECTING ROD CAP IS MESSED UP OR INSTALLED INCORRECTLY DURING MAINTENANCE, IT WILL INEVITABLY CAUSE POOR POSITIONING OF THE JOINT SURFACE SERRATIONS, WHICH CAN EASILY CAUSE THE ENGINE TO LOOSEN THE CONNECTING ROD CAP DURING OPERATION AND LEAD TO THE FRACTURE OF THE CONNECTING ROD BOLTS.③ DURING THE OPERATION OF THE DIESEL ENGINE, IF THERE IS A RUNAWAY FAULT OR THE PISTON BURNS OUT IN THE CYLINDER, THE CONNECTING ROD BOLTS WILL BE PULLED OFF. IF THE ENGINE HAS EXPERIENCED A RUNAWAY FAULT DURING USE, A COMPREHENSIVE INSPECTION OF THE ENGINE SHOULD BE CONDUCTED, PREFERABLY BY REPLACING THE CONNECTING ROD BOLTS; IF SOME CYLINDERS HAVE EXPERIENCED SEVERE CYLINDER PULLING DURING OPERATION, THE CONNECTING ROD BOLTS SHOULD ALSO BE REPLACED WHEN REPLACING THE CYLINDER PISTON COMPONENTS.④ MATERIAL ISSUES, PROCESSING DEFECTS, AND HEAT TREATMENT PROCESS ISSUES CAN ALSO CAUSE CONNECTING ROD BOLTS TO BREAK DURING ENGINE OPERATION.