Which has a longer service life, the pushrod engine or the chain-driven engine?
1 Answers
Structurally speaking, the chain-driven engine is more advanced and durable. Under the same displacement, the chain-driven engine can increase power by raising the rotational speed. It features a compact size, lightweight, lower mechanical load, precise ignition, and can integrate with many advanced technologies. Therefore, high-performance, large-displacement sports bikes mostly use chain-driven engines, but they also demand higher manufacturing technology. More details are as follows: 1. The pushrod engine itself is not suitable for high rotational speeds, so to play to its strengths and avoid weaknesses, most designs feature a small cylinder bore and large stroke, increasing torque and avoiding the drawbacks of high rotational speeds. This results in strong torque at low to medium speeds, powerful acceleration, excellent climbing performance, and good practicality. Chain-driven engines can also be designed this way—simply adjusting the cylinder bore and stroke will suffice—but they cannot match the high-speed performance of chain-driven engines. 2. Generally, either toothed belts or chains are used for transmission. The advantage of toothed belts is that they do not require lubrication and operate quietly, but their lifespan is slightly shorter compared to chains. In contrast, chain-driven systems require lubrication and produce more noise, but they are highly reliable and can last as long as the engine itself. 3. The camshaft is located in the middle of the crankcase. This valve train mostly uses cylindrical timing gears for transmission, typically requiring only a pair of timing gears from the crankshaft to the camshaft, with an intermediate gear added if necessary. To ensure smooth engagement and reduce noise, helical gears are often used for timing gears. The advantage of gear transmission is its accuracy and reliability, but it tends to generate more noise.
