A pushrod is a component found in certain internal combustion engines, particularly those with overhead valve (OHV) configurations. Its primary function is to transfer the motion of the camshaft to open and close the engine's valves.
In an OHV engine, the camshaft is located within the engine block and is responsible for controlling the opening and closing of the intake and exhaust valves. The camshaft has lobes that rotate as the engine operates, and these lobes push against the pushrods.
The pushrods, usually made of metal, are long and cylindrical rods that transmit the motion from the camshaft lobes to the rocker arms or valve lifters. They are typically positioned within the engine block and cylinder head, running parallel to the engine's cylinders.
As the camshaft lobes rotate, they exert pressure on the pushrods, causing them to move up and down. This motion is then transferred to the rocker arms or valve lifters, which ultimately actuate the opening and closing of the engine's valves.
By converting the rotational motion of the camshaft into linear motion, the pushrods play a crucial role in the valve train system of an OHV engine. They help ensure precise valve timing, control the intake and exhaust flow, and contribute to the engine's overall performance and efficiency.
It's important to note that not all engines utilize pushrods. Some engines, such as overhead camshaft (OHC) or dual overhead camshaft (DOHC) engines, employ different mechanisms, such as cam followers or direct-acting camshafts, to operate the valves. These designs eliminate the need for pushrods.