In this case, they’re being used to create a basic PWM motor controller. The trick is to set the 555 up in astable mode, and use diodes and a potentiometer in the charge/discharge loop.

Maxon Precision Motor's ESCON 50/5 OEM module is a 4 quadrant Pulse Width Modulated (PWM) servo motor controller that can efficiently control permanent magnet brushed DC ...

Running a brushed motor in muddy or dusty environments takes a toll on controllers, with both heavy back EMF and high stall currents. This explains one of the challenge in Europe’s Hacky Race… ...

Permanent magnet dc motors need a chunky inductor in series with them if they are fed from an SCR (thyristor) based mains power controller. It is (probably!) possible to safely interface an Arduino to ...