Final answer:
The assertion that brake wear indicators can only be checked with pressurized hydraulic systems is false. Brake wear can often be assessed visually without pressure, although checking for hydraulic issues may require a pressurized system. Pascal's principle allows a hydraulic brake system to evenly distribute force from the pedal to the brakes.
Step-by-step explanation:
The statement that brake wear indicators can only be properly checked with the brakes applied and hydraulic systems #2 and #3 pressurized is false. In the context of hydraulic brakes which use Pascal's principle, brakes can be checked in several conditions, depending on the specific design of the brake system. Most modern cars allow for brake wear indicators to be visually inspected without the need for the hydraulic system to be pressurized. In Pascal's principle applications, such as automotive brakes, the hydraulic system allows for pressure applied on the brake pedal to be evenly distributed to the brake pads or shoes, creating the necessary force to slow down or stop the vehicle effectively.
Brake wear indicators are often designed to emit a noise or visual sign when the pads are thin and need replacement. This can typically be observed without pressurized systems. However, when referring to hydraulic-specific checks such as inspecting for leaks or checking brake line pressure, the presence of pressurized fluid may be necessary. Nevertheless, it is not required for all types of wear indicator checks. It's also important to note that systems must be free of air, as air is compressible and its presence in the brake lines can lead to inefficiency, requiring bleeding for the brakes to function correctly.