The connecting rod upper and lower shells (i.e. the connecting rod large head cover and the connecting rod body) are the key transmission components of the XGC55 crawler crane engine (such as Cummins QSB6.7 or Shangchai SC7H series). They cooperate with the connecting rod bearing bush to convert the reciprocating motion of the piston into the rotating motion of the crankshaft. Forged with high-strength alloy steel (such as 40Cr or 35CrMo), the hardness is HRC28-32, and the design life matches the engine overhaul cycle (about 12,000-15,000 hours).
