TM 5-3825-226-24
Brakes Applied
When the brake pedal is pushed down, both
reaction pistons (2) and (11) go down against valves (6)
and (12). As the pistons contact the valves, they first
seal exhaust passages (8) and (16). If the piston is
pushed down farther, the valves are pushed down
farther and the inlet passages are opened. When the
inlet valves (4) and (15) open, air will go from the supply
passages over the valve and out the delivery passages
(I) and (13).
Hold Position
If the pedal is held in the APPLIED position, force
from the delivery air pressure will move reaction pistons
(2) and (11) up against the metering spring (3). If the
pedal is pushed a small amount (metering spring force
low), the force of the delivery air pressure will raise the
reaction pistons and valves (6) and (12) enough to seal
the inlet part of the valves. In the HOLD position, the
delivery pressure raises the pistons and valves enough
to shut off its supply. If the delivery pressure goes
down, metering spring (3) opens the valves to let supply
air go in. The action of the metering spring and the
reaction pistons keep the delivery pressure constant at
each pedal position. The harder the pedal is pushed,
the higher the pressure delivered. Passage (9) keeps
equal delivery air pressure between the front and rear
brakes. To do this, passage (9) lets balance pressure
act on each reaction piston. If one brake system (tractor
or water distributor) should fail, push rod (10) will let the
valve stay in operation.
Brake Released
All force is removed from metering spring (3) and
reaction pistons (2) and (11) move up. Air flow from the
two supply ports is blocked by both inlet valves (18) and
(20). Both delivery passages (17) and (19) are open to
exhaust.
Air Chambers and Master Cylinders
The brake system for the tractor has one air
chamber and one hydraulic brake master cylinder. The
brake system for the water distributor has one air
chamber and one hydraulic brake master cylinder. The
air chambers activate the pistons of the hydraulic brake
master cylinders. Compressed air in air chamber (A) is
pushed against diaphragm (B) to move the air chamber
rod (D) out. When the rod is moved out, it will push on
the back of piston (E). The diaphragm and rod are
pushed back by spring (C) when the air pressure is
released.
AIR CHAMBER AND MASTER CYLINDER
A. Air chamber. B. Diaphragm. C. Spring. D. Rod. E.
Piston.
WATER DISTRIBUTOR AIR CHAMBER AND
MASTER CYLINDER
7. Master cylinder. 8. Air chamber. 9. Air line.
10. 011 line to water distributor brakes. 11. Valve.
12. Stroke Indicator. 13. Quick release valve.
NOTE: The valves (3) and ( 1) let about 3 to 6 psi (20 to
40 kPa) oil pressure to be in the lines. This pressure will
be enough to let the brake pads release from the brake
discs but will keep a small amount of pressure so that
the brake pads will clean themselves.
TRACTOR AIR CHAMBER AND MASTER CYLINDER
1. Air line. 2. Master cylinder. 3. Valve. 4. Oil line to
tractor brakes. 5. Air chamber. 6. Stroke Indicator.
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