Mechanisms for reducing power output of a power tool by restricting airflow into the motor of the tool. The power regulator can be implemented in only one of the rotational directions, for example, the forward (or clockwise) direction, and can be independent of the forward/reverse mechanism to avoid a user becoming confused as to the source of tactile feedback. By limiting air input to the motor, rather than bleeding out motor output, the mechanisms prevent wasted power output. Also, the power regulation mechanism can be located near the motor to more effectively restrict airflow.