What is Included in the Valve Train?

Within an internal combustion engine, the valve train is charged with the management and operation of intake and exhaust valves. While the intake valve supplies the combustion chamber with an air-fuel mixture, the exhaust valve ensures that all spent gases are removed after use. Valve trains are composed of numerous parts that work together, and it is important that they are all well maintained and functional for operations to be carried out properly. In this blog, we will provide a brief overview of the most common valve train components, allowing you to better understand how such devices work.


The camshaft comes in the form of a long shaft passing through the head or engine block, varying based on the type of engine that is present. Lobes are situated along the shaft’s length, and each can be described as “egg” shaped. The dimension of each lobe will have a direct effect on the amount of lift, that of which determines how long each valve will stay open to permit airflow into the cylinder.

Camshaft Followers

The cam follower trails along the camshaft lobes as they rotate, allowing for a low-resistance surface to be provided for the lobes to press on. Cam followers may come in a variety of sub-types, each of which follows configurations based on how they are mounted to a mating component. Often, camshaft followers are featured when the cam is in the block, rather than when it is overhead.


Pushrods will regularly be in engines where the cam is in the block, therefore not always being present in every diesel engine. Generally, such components are rods that push up against rocker arms. The movement of the pushrod is dependent on the movement of the camshaft follower. Beyond such roles, they may also be used to transfer oil up to the cylinder head.


Valves serve as a major element of valve trains, and such components are composed of a valve head and valve stem. The head permits air to enter and escape the cylinder, while the stem is pressed on by the valve train. Generally, engines will feature anywhere from two to four valves per cylinder, heavy-duty types featuring four.

Valve Springs

As the camshaft pushes on the rocker arm, the rocker arm will press down on the valve. When the cam rotates, on the other hand, it will not be able to pull the other components back with it. As such, valve springs are used to create force in the opposite direction so that the valve may be closed again. Generally, the force of the spring will maintain the valve in a closed position until the lobe surpasses its strength.

Timing Belt

To properly turn the camshafts, a timing belt may be implemented in lieu of a timing chain. The inner side of the belt often features square-shaped teeth, ensuring that the belt does not loosen. To keep the timing belt in tension, a belt tensioner in the form of a spring-loaded wheel is used.

Beyond such components, there are other various parts of the valve train that ensure proper operations. If you are maintaining your valve train and find that you require various parts for replacement, let the experts at Fulfillment 3Sixty save you time and money during the purchasing process. Fulfillment 3Sixty is an online distributor of aircraft parts and other various items, providing competitive pricing and rapid lead-times on over 2 billion new, used, obsolete, and hard-to-find items. Take the time to explore our vast offerings at your leisure, and our team of industry experts is always ready to assist you through the purchasing process as necessary. Get started today and see why customers choose to steadily rely on Fulfillment 3Sixty for all their operational needs.


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