Rocker arm
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A cam follower (also rocker arm ) is an in internal combustion engines employed levers for transmitting movements curve of a cam of the camshaft to the intake and exhaust valves .
The rocker arm is a one-way lever . It rotates on one side and rests on the valve at the other end. In contrast to the arrangement on the rocker arm , the camshaft is above the rocker arm . The camshaft operates the rocker arm from above without any intermediate links. Variants with a roller tap on ball bearings are also common. In the case of a roller rocker arm, there is a roller mounted in the engagement area of the camshaft. This role reduces the friction in the valve train by around 30%. Typically, the valve spring pushes the rocker arm back into its starting position as soon as the camshaft has continued to rotate. Some designs have a separate return spring to return the rocker arm to its starting position.
The forces acting on the rocker arm are lower compared to the rocker arm drive. Another advantage is the simple implementation of valve clearance compensation. The pivot point is adjusted vertically to compensate for the valve clearance. The compensation elements are not part of the moving masses, the rocker arm only rests on them.
Rocker arms are usually made of sheet metal or cast steel.
literature
- Richard van Basshuysen, Fred Schäfer: Handbook Internal Combustion Engine: Fundamentals, Components, Systems, Perspectives. 8th edition, Springer Vieweg, Wiesbaden, 2017, ISBN 978-3-658-10901-1 . Pp. 193–217, (209ff., 284 and 285)