Impact driver

An impact driver is a tool that delivers a strong, sudden rotational force and forward thrust.

Manual impact drivers consist of a heavy outer sleeve that surrounds an inner core that is splined to it.

The tool translates the heavy rotational inertia of the sleeve to the lighter core to generate large amounts of torque.

At the same time, the striking blow from the hammer forces the impact driver forward into the screw reducing or eliminating cam out.

Typical battery-powered impact drivers are similar to electric drills when used to drive screws or bolts, but additionally have a spring-driven mechanism that applies rotational striking blows once the torque required becomes too great for the motor alone.