In general, the independent-type brake system is used on small aircraft. This type of brake system is termed independent because it has its own reservoir and is entirely independent of the aircrafts main hydraulic system.

The independent-type brake system is powered by master cylinders similar to those used in the conventional automobile brake system. However, there is one major differencethe aircraft brake system has two master cylinders while the automobile system has only one.

An installation diagram of a typical independent-type broke system is shown in figure 12-22. The system is composed of a reservoir, two master cylinders, and mechanical linkage, which connects each master cylinder with its corresponding brake pedal, connecting fluid lines, and a brake assembly in each main landing gear wheel.

Each master cylinder is actuated by toe pressure on its related pedal The master cylinder builds up pressure by the movement of a piston inside a sealed fluid-filled cylinder. The resulting hydraulic pressure is transmitted

Figure 12-22.-Typical independent-type brake system.

to the fluid line, which is connected to the brake assembly in the wheel. This action results in the friction necessary to stop the wheel.

When the brake pedal is released, the master cylinder piston is returned to the OFF position by a return spring. Fluid that was moved into the brake assembly is then pushed back to the master cylinder by a piston in the brake assembly. The brake assembly piston is returned to the OFF position by a return spring in the brake.

The typical master cylinder has a compensating port or valve that permits fluid to flow from the brake chamber back to the reservoir when excessive pressure is developed in the brake line due to temperature changes. This feature ensures against dragging or locked brakes.

Various manufacturers have designed master cylinders for use on aircraft. All are similar in operation, differing only in minor details and construction. Two types of master cylinders, the Goodyear and the Gladden, are described and illustrated in this section.

Figure 12-23.-Goodyear master brake cylinder.