Drill trigger: working principle

The trigger is a simple electronic device which regulates the voltage output to the DC-motor. The battery pack is at 14.4V, but the trigger enables you to send a lower voltage to the DC-motor by pressing it less, as can be seen in de video above.

Right above the trigger, there's a slide switch. This inverts the voltage to DC-motor. Enabling you to make the drill spin in the opposite direction.