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Section 250-0000
Braking System - Air Braking System Schematic
SM 1948 4-00
Solenoid Valve (16) - When the solenoid valve is
activated by the differential lock switch, air pressure
from the primary tank is directed to the differential lock
cylinders. The valve also exhausts air pressure from
the differential lock cylinders.
Differential Lock Cylinders (17) - There are two
differential lock cylinders on each machine. One
mounted on the frame, adjacent to the transmission
and the other integral with the centre differential. When
actuated, the cylinders lock the transmission and inter-
axle differentials. The transmission differential lock
requires air pressure to hold it 'Off', whereas, the
centre axle differential lock requires pressure to hold it
'On'.
Levelling Valve (18) - Maintains the front suspension
at the proper ride height. Refer to Section 180-0022,
LEVELLING VALVE, for detailed operating and
servicing procedures.
Air Springs (19) - Expand or retract according to the
air flow from the levelling valve. Refer to Section
180-0021, AIR SPRING, for detailed operating and
servicing procedures.
Differential Lock Warning Light (Amber) -
Illuminates when the differential lock switch is
activated to the 'ON' position to indicate transmission
and inter-axle differential locks are applied.
Note: Refer to operators handbook for location and
identification of warning light.
Air Pressure Gauge - Located on the instrument
panel it indicates system air pressure.
OPERATION
Numbers in parentheses refer to Figs. 1.
Air from the engine driven air compressor (2) travels
through air drier kit (3) and into primary tank (5) and
front brake tank (6) via pressure protection valve (9).
Primary tank (5) is the outside tank positioned at the
front left-hand side of the tractor frame.
Air is supplied to the suspension system levelling
valve (18) and coolant sensor valve from port 'F' in the
primary tank (5). Air is supplied to solenoid valve (16)
and regulating valve (20) via port 'D' in the primary
tank (5). If air pressure in primary tank (5) falls below
4.1 bar (60 lbf/in²), low pressure switch fitted in port 'A'
sends a signal and the low pressure warning light
illuminates in the cab.
DESCRIPTION
The air brake system is an integral part of the service
brake system. The system is used to supply air
pressure for operating the front and rear pressure
converters which in turn, actuate the front and rear
brake hydraulic systems for applying the disc brakes.
The air system also supplies pressure for operating air
actuated accessories such as the transmission and
inter-axle differential locks, fan clutch, transmission
retarder and the suspension system.
The safety air brake system on the machine has the
following features:
1. Low air pressure warning light which illuminates
when air pressure drops below 4.1 bar (60 lbf/in²).
2. Automatic brake apply when system air pressure
falls below 3.1 bar (45 lbf/in²).
3. Separate front and rear braking circuits with
individual warning lights to warn if system pressure
falls. A buzzer also sounds when pressure falls.
4. Service brake apply to temporarily hold the machine
stationary by moving the park/emergency control valve
lever into the 'EMERGENCY' position. When parking
the machine for an extended period of time apply the
parking brake.
5. Air released - spring applied parking brake
controlled by the park/emergency control valve.
Parking brake is applied when the control valve lever
is in the 'PARK' position.
6. Pressure converters which are equipped with an
overstroke indicator.
AIR SYSTEM AUXILIARY COMPONENTS
Numbers in parentheses refer to Fig. 1.
The following is a list of auxiliary components used in
the air system, with a brief description of each:
Kysor DST Fan Clutch (1) - Direct temperature
sensing fan. Refer to Section 110-0040, KYSOR DST
FAN, for detailed operating and servicing procedures.
Pressure Protection Valve (9) - Supplies air to all
three air tanks for the service brakes, secondary
braking and accessory devices. Refer to Section
250-0290, PRESSURE PROTECTION VALVE, for
detailed operating and servicing procedures.
Courtesy of Machine.Market
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