What is the Crank Connecting Rod Mechanism Composed Of?
4 Answers
The crank connecting rod mechanism is composed of components such as the piston group, connecting rod group, crankshaft, and flywheel group. It serves as the main moving part of the engine to achieve the working cycle and complete energy conversion. During the power stroke, the piston moves linearly in the cylinder under the pressure of the combustion gas, converting this motion into the rotational movement of the crankshaft through the connecting rod, thereby outputting power externally. During the intake, compression, and exhaust strokes, the flywheel releases energy, converting the rotational movement of the crankshaft back into the linear motion of the piston. The function of the crank connecting rod mechanism is to provide a combustion chamber, transform the expansion pressure of the gas generated after fuel combustion acting on the top of the piston into the torque of the crankshaft's rotation, and continuously output power.
The crankshaft-connecting rod mechanism is truly the heart of an engine! After years of working with cars, I'm most familiar with this component. It consists of three major parts: the piston assembly, connecting rod assembly, and crankshaft-flywheel assembly. The piston assembly includes the piston with piston rings and piston pin, moving up and down in the cylinder; the connecting rod assembly acts like a linkage, connecting the piston at one end and embracing the crankshaft at the other; while the crankshaft-flywheel assembly is the core, converting linear motion into rotational power. I've personally witnessed small-displacement engines losing power due to deformed connecting rods, and experienced oil burning caused by worn piston rings. The entire mechanism operates under high temperature and pressure, relying entirely on the lubrication system for protection. Using inferior engine oil can make the metal parts grind against each other with unbearable noise. Regular maintenance requires special attention - when this system fails, it's never a minor repair job.
When working on cars, I often deal with the crankshaft-connecting rod mechanism, which consists of three parts working in coordination. The piston assembly mainly includes the piston and piston rings, moving up and down in the cylinder liner; the connecting rod assembly is the connecting rod, linking the piston above to the crankshaft below; the crankshaft-flywheel assembly includes the crankshaft and flywheel, converting the up-and-down motion into rotation. I've listened to the operating sounds with a stethoscope—normally, it's a regular puffing sound, but if a tapping sound appears, it might indicate a loose piston pin. Metal fatigue is a common issue, especially for heavy-duty trucks under long-term high loads—I've seen cases of connecting rod bolt fractures seven or eight times. The assembly precision requirements are extremely high; even a 0.05 mm gap difference in the crankshaft main bearing or connecting rod bearing can cause vibrations. That's why I always use a torque wrench to tighten the bolts in sequence during every disassembly and assembly.
I've disassembled motorcycle engines before. The crank-connecting rod mechanism is the mechanical device where the piston connects to the crankshaft. The piston assembly moves within the cylinder, sealed by piston rings; the connecting rod resembles an iron rod, linking the piston and crankshaft at both ends; the crankshaft tail carries the flywheel. This system converts the explosive force of fuel into rotational power. The most common issue in daily use is carbon buildup on piston rings, leading to oil burning and blue smoke from the engine. When modifying, it's important to note that strengthening this mechanism can increase power, but choosing the wrong piston material or crankshaft counterweight can actually shorten its lifespan.
