Using the Brake System Operating Instructions
– 90 – Y53-6008
Medium Duty (R10/06)
Brake Master Cylinder: translates brake pedal force into
hydraulic fluid pressure in the primary and secondary cir-
cuits.
Brake Pedal: applies actuation force from operator's foot to
the master cylinder pistons.
Brake Warning Lamp: illuminates when either power steer-
ing 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 to the hydraulic booster in the event
power steering fluid stops flowing through the booster head.
Front and Rear Wheel Calipers: translate hydraulic fluid
pressure into force applied at each wheel-end brake rotor to
retard wheel motion.
Hydraulic Booster: The hydraulic booster applies additional
hydraulic force from the power steering gear to the master
cylinder piston when the brake pedal is applied.
Parking Brake Lamp: illuminates when the parking brake is
engaged (the lever is in the up position.)
Parking Brake Lever: the hand lever located in the cab
which engages or disengages the driveline drum brake.
Power Steering Flow Switch: senses flow of power steering
fluid.
Power Steering Fluid Reservoir: stores power steering fluid
and offers a place to replenish when needed.
Power Steering Gear: assists the steering operation and
sends pressurized power steering fluid to the brake booster.
Power Steering Pump: draws power steering fluid from the
reservoir and sends it to the power steering gear.
Warning Buzzer: sounds when either power steering fluid
flow is interrupted or when a pressure differential is present
between the primary and secondary brake fluid pressure.
Either case adversely affects braking operation.
