FLOW OF AIR; RELEASING OF PARKING BRAKE
1. Knob and pin assembly. 2. Valve body. 3. Spring.
4. Orifice. 5. Outlet (to chamber of the parking
brake). 6. Inlet (from air reservoir). 7. Exhaust (to
atmosphere). 8.
The control valve will be ON when there is little air in
the air reservoir [knob (1) pulled out]. Valve (8) is
against the upper face of valve body) (2) to stop
pressure air to outlet (5) and exhaust (7). Air in the
reservoir goes up to the necessary range.
When the pressure gauge gives the indication that
the necessary air is in the reservoir, push in and hold
knob (1) to release the parking brake. Pressure air from
the reservoir goes in inlet 96), through orifice (4) and
through outlet (5), into the brake chamber, to release the
parking brake. Air pressure holds valve assembly (8)
over exhaust (7).
If the air pressure in the system goes below 40 5
psi (280 35 kPa), spring (3) moves valve assembly (8),
opening exhaust (7). Pressure air goes to the
atmosphere and the parking brake activates.
EMERGENCY BRAKE CONTROL VALVE
EMERGENCY BRAKE CONTROL VALVE
The emergency brake control valve has control over
the supply of air to the emergency pilot valve. When the
engine is first started and the control valve is in the ON
(pulled out) position, the line to the emergency pilot valve
has no pressure in it. The pilot valve is open and air flow
from the reserve tank activates the tractor and scraper
brakes.
When the emergency control valve is in the OFF
(pushed in) position, air pressure then fills the line to the
pilot valve and closes it. Air flow from the reserve tank is
stopped and the tractor and scraper brakes are released.
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