What components apply hydraulic force to slow and stop the vehicle?

Calipers and wheel cylinders are the components that apply hydraulic force to slow and stop a vehicle. This is because they are integral parts of the hydraulic braking system. When the brake pedal is pressed, hydraulic fluid is pushed through brake lines to the calipers (in disc brakes) or wheel cylinders (in drum brakes).

In the case of disc brakes, calipers compress the brake pads against the rotors, creating friction that slows down the wheels. Similarly, for drum brakes, wheel cylinders push the brake shoes against the drum, also generating the necessary friction. This hydraulic system is effective because it can amplify the force exerted by the driver on the brake pedal, allowing for effective braking power with relatively little physical effort.

The other components listed, such as brake pads and rotors, are crucial in the braking process, but they do not apply hydraulic force; instead, they are the friction components that work in conjunction with the hydraulic force from the calipers and wheel cylinders. Piston rings and crankshafts are related to the engine's function, not braking. Similarly, absorbers and springs are part of the suspension system, not directly involved in the braking mechanism.