Gauge Pressure plate Brake housing Master cylinder Clear hose Pressure pot Brake reservoir Pressure gauge Filler plug Air valve D-rigid nozzle Flexible nozzle 13-69 Figure 13-118.  Arrangement for bottom-up pressure bleeding of  aircraft brakes. Fluid is pushed through the system until no air  bubbles are visible in the hose at the top.  Figure 13-117.  A typical brake bleeder pot or tank contains pure  brake fluid under pressure. It pushes the fluid through the brake  system to displace any air that may be present. Figure 13-116.  The distance between the brake housing and the  pressure plate indicates lining wear on some multiple disc brakes. of brake fluid under pressure. When dispersing fluid from  the tank, pure air-free fluid is forced from near the bottom  of the tank by the air pressure above it. The outlet hose that  attaches the bleed port on the brake assembly contains a shut- off valve. Note that a similar source of pure, pressurized fluid  can be substituted for a pressure tank, such as a hand-pump  type unit found in some hangars. The typical pressure bleed is accomplished as illustrated in  Figure 13-118 . The hose from the pressure tank is attached to  the bleed port on the brake assembly. A clear hose is attached  to the vent port on the aircraft brake fluid reservoir or on the  master cylinder if it incorporates the reservoir. The other end  of this hose is placed in a collection container with a supply  of clean brake fluid covering the end of the hose. The brake  assembly bleed port is opened. The valve on the pressure tank  hose is then opened allowing pure, air-free fluid to enter the  brake system. Fluid containing trapped air is expelled through  the hose attached to the vent port of the reservoir. The clear  hose is monitored for air bubbles. When they cease to exist, 