What is the composition of the valve train assembly?
2 Answers
The valve train assembly consists of the valve timing gear, camshaft and its components, rocker arm shaft and rocker arm assembly, valve pushrod, valve, cylinder head, valve seat, valve guide, valve spring, valve lock and its components, valve adjusting screw, and other parts. Below is a related introduction: 1. Camshaft: It is the main component of the valve train assembly, responsible for controlling the opening and closing of the valves and the variation pattern of their lift. In engines with a lower-mounted camshaft, it also drives devices such as the fuel pump, oil pump, and distributor. 2. Tappet: Its function is to transmit the thrust generated by the rotation of the camshaft to the pushrod (in lower or mid-mounted camshaft configurations) or directly to the valve (in overhead camshaft configurations). Tappets are generally made of wear-resistant alloy steel or cast iron. 3. Pushrod: In valve trains with a lower-mounted camshaft, there are slender pushrods that transmit the camshaft's thrust from the tappet to the rocker arm mechanism. 4. Rocker arm: It changes the direction of the force transmitted by the pushrod or camshaft and applies it to the valve to open it. The rocker arm assembly mainly consists of the rocker arm, rocker arm shaft, support seat, and valve clearance adjusting screw.
The valve train plays a crucial role in the engine, responsible for controlling the opening and closing of valves to allow smooth intake of fresh air and exhaust of combustion gases. Based on my years of auto repair experience, its components are quite straightforward: the camshaft is the core—when it rotates, it pushes the tappet, which connects to the pushrod. The pushrod transmits force to the rocker arm, which acts like a lever to open the valve. Every part matters. For instance, the camshaft determines valve timing, pushrods need lightweight design to reduce inertia, and rocker arms must ensure sufficient force to open valves. Poor maintenance can lead to issues: insufficient oil causes tappet noise, worn rocker arms result in incomplete valve opening, and the engine instantly loses power. I recommend frequent oil changes and regular valve clearance checks—this improves fuel efficiency and extends engine life, especially valuable in city traffic jams.
