Peterbilt 325 2017, Operator'S Manual

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OPERATING THE BRAKE SYSTEM
WARNING!
The brake system is a critical vehicle
safety system. For the safety of you
and others around you, have the ve-
hicle submitted for periodic preven-
tive maintenance checks as well as
having any suspected problems im-
mediately checked by an Authorized
Service Center. Failure to properly
maintain your brake system can lead
to serious injury accidents.
Brake Components
The following is a brief description
of the hydraulic brake system. It is
intended to supply you with general
information on how the system works.
For complete information see the
Peterbilt Medium Duty Maintenance
Manual.
Anti-Lock Brake System (ABS)
Modulator Valve Body:
adjusts brake
fluid flow between the master cylinder
and the wheel calipers to avoid wheel
lockup.
ABS Warning Lamp: lights when the
ABS controller detects wheel lock-up
while driving and activates the ABS.
Lights also when a fault in the ABS is
detected.
Brake Fluid Reservoir: stores brake
fluid and offers a place to replenish
when needed.
Brake Master Cylinder: translates
brake pedal force into hydraulic fluid
pressure in the primary and secondary
circuits.
Brake Pedal: applies actuation force
from operator's foot to the master
cylinder pistons.
Brake Warning Lamp: illuminates
when either power steering fluid flow
is interrupted or when a pressure
differential is present in the primary
and secondary brake fluid pressure.
Either case adversely affects braking
operation.
Differential Switch: measures the
hydraulic fluid pressure difference
between the primary and secondary
circuits.
Electrohydraulic Pump: The
Electrohydraulic (EH) pump is used as
a backup boost pump. The EH pump
turns on and provides fluid pressure
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