A I R S Y S T E M A N D B R A K E S
S Y S T E M S O P E R A T I O N
sion engages before the wheel
This action keeps the machine
brakes are released.
from free movement
(rolling) when the machine is on a slope.
The emergency and parking brake is controlled
manually by the knob directly under the steering
wheel. The brake will operate automatically if the air
pressure in the system gets too low.
The brake system is divided into four different
circuits: air supply for the air system, air circuit for
the emergency and parking brake, air circuit for the
wheel brakes and hydraulic circuit for the wheel
brakes. The brake system is separated into these four
parts to make its explanation easier.
The air supply provides the air under pressure to
operate the brake system. Air compressor (21), gover-
nor (20) and air reservoir (8) and its valves make up
the air supply. On models 950BNSCE and 950BSCE,
air dryer is also a component of the air supply.
The air circuit for the emergency and parking
brake provides protection for the machine if there is a
failure in the air system. Emergency and parking
brake (15) and its brake chamber (14), quick release
valve (16), air pressure switch (5) and control valve
(3) are components of this circuit.
The air circuit for the wheel brakes sends air
to operate the air horn and to activate the hydraulic
circuit for the wheel brakes. The components of
the air circuit for the wheel brakes are: horn valve
(10), air horns (9), air pressure switch (2) for wheel
brakes, left pedal (12) and its brake control valve
(11), right pedal (30) and its brake control valve
(29), orifice check valve (33), double check valve
(32), air pressure switch (31) for stop lights, and
two air cylinders [part of air/hydraulic cylinders
(22) and (26)].
The hydraulic circuit for the wheel brakes en-
gages the wheel brakes when the air circuit causes
brake fluid pressure in the hydraulic circuit. The
components of the hydraulic circuit are: two master
cylinders [part of air/hydraulic cylinders (22) and
(26)], two brake fluid reservoirs (23) and (27), brake
fluid pressure (overstroke) switches (25) for wheel
brakes and four wheel brakes (34).
When the engine is running, loss of brake air pres-
sure will cause brake air pressure indicator (4) and
master fault light (1) to come ON, the fault alarm
will sound and the emergency and parking brake will
M A S T E R F A U L T L I G H T
When the emergency and parking brake is en-
gaged, and the transmission is disengaged, parking
brake indicator (3) will come ON. When the trans-
mission is engaged and the emergency and parking
brake is engaged, parking brake indicator (3) and
master fault light (1) will come ON, and the fault
alarm will sound. Also, when the transmission is
engaged and the parking brake is engaged, the trans-
mission neutralizer group automatically disengages
Too much master cylinder stroke (loss of hydraulic
pressure) in the front or rear hydraulic circuit will
cause brake fluid pressure indicator (2) and master
fault light (1) to come ON, and the fault alarm will
W A R N I N G
I N D I C A T O R S
2. Brake fluid pressure indicator. 3. Parking brake indica-
tor. 4. Brake air pressure indicator.