Manual impact driver 1

The blue sleeve and the yellow core are connected together by a helical joint (helical spline).
When the user strikes the outer sleeve with a hammer (represented by the brown arrow), its downward force works on the spline to produce turning force on the core and any socket (red) attached to it.
The tool translates the heavy rotational inertia of the sleeve to the lighter core to generate large amounts of torque to loosen the rusty or over-torqued screw (pink).
This video was made based on an actual tool shown at:
https://youtu.be/vUKGBv596RI

Видео Manual impact driver 1 канала thang010146