What are the components of the valve train?
3 Answers
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. Content expansion: 1. When the camshaft rotates and the base circle part of the cam contacts the tappet, the tappet does not rise, and the transmission parts above the tappet do not move, because the valve is closed. 2. When the raised part of the cam contacts the tappet, it starts to lift the tappet, thereby opening the valve. When the highest raised part of the cam contacts the tappet, the valve reaches its maximum opening. 3. 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. 4. When the raised part of the cam leaves the tappet, the valve is completely closed.
I've been learning car repair recently and discovered that the valve train is actually the core component controlling the engine's intake and exhaust system. It mainly consists of valves (including intake and exhaust valves), camshaft, rocker arms, valve springs, and timing belt or chain. The valves act like small gates, with the camshaft determining their opening and closing timing through rotation, while the rocker arms and springs help transmit force and maintain sealing. My friend's car was shaking badly last time, and after inspection, we found that a valve spring had broken, causing improper intake and exhaust which affected power output. When driving normally, pay attention to wear on these components, especially the timing system - if the chain becomes too loose it can deviate from timing position. For new car maintenance, regularly replacing the chain can save money. Neglecting this might leave your entire vehicle stranded. Understanding these basics can help us beginners get started with car maintenance faster.
I've been driving trucks for over a decade, and I'm quite familiar with the composition of the valve train: components like valves, camshafts, rocker arms, pushrods, and valve springs work together. The camshaft drives the rocker arms, which push the valves open and closed, while the springs ensure a tight seal. In older engines, there are also lifters and bushings involved. In daily use, issues often arise with the timing chain. Wear on the chain can lead to incorrect valve timing, and in severe cases, cylinder damage. I've encountered this a few times—when the speed gets high, the engine misfires, and upon inspection, it turns out the chain needs replacing. During maintenance, keeping the engine oil clean is crucial to prevent carbon buildup from clogging the valves. I recommend that vehicle owners check every 50,000 kilometers—don’t wait until there’s strange noise to panic. It saves both money and hassle.
