TM 5-3805-260-24
AIR CHAMBER AND MASTER CYLINDER OPERATION
1. Air chamber inlet
4.
Air chamber assembly.
9.
Master cylinder 12.
Plate.
17. Valve.
passage from brake
5.
Spring.
assembly.
13. Cup.
18. Cup.
valve.
6.
Supply passage.
10. Master cylinder outlet 14. Indicator.
19. Spring.
2. Diaphragm.
7.
Cap.
passage.
15. Piston.
20. Residual
3. Boot.
8.
Bypass passage.
11. Rod assembly.
16. Passages.
pressure
valve (check
valve).
When the brake is pushed, it sends air from the brake
control valve through passage (1) to the air compartment
of air chamber (4). Pressure air will push on the back of
diaphragm (2) and rod assembly ( 11) and move the
diaphragm (2), rod assembly) (11). indicator (14) and
piston (15) to the right. As piston (15) moves cup (18)
past bypass passage (8), brake fluid in the master)
cylinder bore will go through passage (10) and residual
pressure valve (check valve) (20) to the wheel cylinders.
When the brake pedal is released, pressure air is let
out of air chamber (4) and spring (5) moves diaphragm
(2) and rod assembly) (11) to the released position.
Diaphragm (2) and rod assembly (11) moves faster than
piston (15) because of the brake fluid which must be
removed. This will cause a reduction in the pressure
area between cup (18) and residual pressure valve
(check valve) (20). Brake fluid ahead of cup (13) is pulled
through passage (6), passages (16) in piston ( 15) and
past valve (17).
When the brake fluid moves back through residual
pressure valve (check valve) (20), spring (19) moves cup
(18) and piston (15) toward plate (12).
When piston 15) contacts plate (12), bypass passage
(8) is open to the master cylinder bore. Residual
pressure valve (check valve) (20) keeps a small amount
of residual pressure (back pressure) in the brake
hydraulic system Cap (7) has passages to let air
pressure out of the master cylinder reservoir. The brake
fluid pushed
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