harmonic balancer

The main drive pulley of an engine; mounted on the fromt end of the crankshaft. Harmonic balancers are weighted to keep the crankshaft balance in order to reduce vibration.

Frank: The dang harmonic balancer is frozen to the crankshaft!
Allan: Probably gonna have to use a harmonic balancer puller, Frank.
Frank: Wow! They actually make those?!
Allan: Yep