What are the main components of the valve train?

[ValentinaRose]

Here is an introduction to the composition and working principle of the valve train: 1. Composition of the valve train: The valve train consists of two groups: the valve drive group and the valve group. The valve drive group includes the crankshaft timing gear, camshaft timing gear, camshaft, tappet, push rod, rocker arm, valve clearance adjustment screw and lock nut, and rocker arm shaft. The valve group includes the valve, valve guide, valve spring, valve spring seat, valve oil seal, and valve seat. 2. Working principle of the valve train: When the camshaft rotates, and the base circle part of the cam is in contact with the tappet, the tappet does not rise, and the transmission parts above the tappet do not move, keeping the valve closed. When the raised part of the cam comes into contact with the tappet, it begins to lift the tappet, thereby opening the valve. When the maximum raised part of the cam contacts the tappet, the valve reaches its maximum opening. Subsequently, the raised surface of the cam in contact with the tappet begins to gradually decrease, and the valve starts to close under the action of the valve spring, reversely pushing the rocker arm and other transmission components, causing the tappet to move downward to maintain contact with the cam. When the raised part of the cam leaves the tappet, the valve is completely closed.

[DelAdaline]

I often encounter the valve train system when repairing cars, which is the key system controlling engine intake and exhaust. Core components include the camshaft, rocker arms, valves, and springs. When the camshaft rotates, its lobes push the rocker arms, which then open the valves to let air and fuel into the cylinders; the springs then pull the valves back to close them. If the camshaft wears out, causing improper valve timing, the engine will lose power and emit black smoke, affecting fuel economy. During routine maintenance, it's important to check the cleanliness of the engine oil to prevent accelerated wear from debris buildup. For example, running at high temperatures can cause rocker arms to stick, affecting idle stability. Remember, timely repairs can save you a lot of money.

[Alessandra]

I've been driving a vintage car for almost ten years, and once had a close call with a breakdown due to a valve train malfunction. From the mechanic, I learned it mainly consists of components like the camshaft, valve group, and rocker arm springs. The camshaft acts like a rotating rod, pushing the rocker arms up and down to control the opening and closing of the intake and exhaust valves. The exhaust valve specifically expels waste gases, while the intake valve draws in fresh air. If these fail, the engine will shake, lose power, and consume more fuel. I always pay attention to changing the oil to reduce friction—this kind of maintenance is simple but crucial. It ensures the engine runs smoothly, especially noticeable during high-speed long-distance drives.

[StAiden]

Think of the valve train as the engine's respiratory system, an analogy I often use in lectures. The core components—camshaft, valves, rocker arms, and springs—work in harmony: as the camshaft rotates, its lobes lift the rocker arms to open the valves for air intake; the springs then close the valves. Precise timing of intake and exhaust valve operation is crucial for controlling the fuel-air mixture flow. Failures like loose rocker arms or broken springs can cause air leaks, reducing compression ratio and affecting ignition. Understanding this mechanism aids in diagnosing common issues like rough idling, while using high-quality engine oil can extend its lifespan.