When the switches from S1 to S3 are pressed for a moment, the motor receives the voltage of B1, B2 B3 more, adding to the voltage of B2 that feeds the circuit. With this it can have a momentary increase in torque, or it can be important to remove an automation from immobility, overcoming inertia. This circuit is from the book Robotics, Mechatronics and Artificial Intelligence by Newton C. Braga.
