This is the model of an impact drill / driver mechanism. The rotary and translational motions related to the motor input are applied on the camshaft, which is connected to a hammer through a (both tortional and translational) spring which causes the hammer to vibrate freely as it impacts repeatedly on the anvil. The translational and rotational motions of the hammer, which moves along the groove on the camshaft, are related by the cam lead and the relative angle between the camshaft and the hammer.

After each impact, the hammer rebounds by a small amount. This allows the hammer to climb over the anvil and impact with the anvil again in the next 180 degrees (Pi rad). The hammer hits the anvil every 180 degrees and produces the impact torque to push the screw into the wood.

The sliding friction that holds the screw in the wood is modeled as a function of the angular velocity of the screw. This friction approximates the sum of Stribeck friction and Coulomb friction.