Final answer:
In an ADVANCED leading/trailing type drum brake system, various springs are utilized and a hydraulic system based on Pascal's principle allows even force distribution across wheel cylinders. Power brakes in larger vehicles incorporate a motorized pump to assist with force application.
Step-by-step explanation:
The ADVANCED leading/trailing type drum brake system uses several types of springs to operate efficiently. A key component to this system is the hydraulic system, which operates on Pascal's principle. This principle ensures that when the driver exerts a force on the brake pedal, this force is multiplied by a combination of a simple lever and the hydraulic system. The increased force is then evenly distributed to the wheel cylinders, which in turn press the brake shoes against the drum to create the necessary friction to stop the vehicle. In more complex systems, such as power brakes found in commercial vehicles or heavy machinery like bulldozers, there is an additional motorized pump that further assists in applying the required force to stop the vehicle.