rocker arm

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A pivoted lever used in an internal combustion engine to transfer cam or pushrod motion to a valve stem.

from The Century Dictionary.

• noun An arm or lever attached to a rock-shaft so that it may receive or give a reciprocating angular motion.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a lever pivoted at the center; used especially to push a valve down in an internal-combustion engine