PREVOST H3-41 Maintenance Manual page 452

SECTION 12: BRAKE AND AIR SYSTEM
hold solenoid is normally open and the release
solenoid is normally closed, such that the PMV
nominally allows air to flow through. This design
allows for air delivery to brake chambers in the
event of electrical trouble. This is an "On/Off"
type valve, i.e., during an antilock activity, the
valve exhausts air from the brake chamber when
in a ABS event, the electronic unit senses that
the corresponding wheel speed is decreasing in
relation to the other wheels.
The EC-80 controller also utilizes an additional
PMV for control of the trailer service brakes
during stability interventions.
6s/5m Configuration
Prevost vehicles utilize a 6 sensors/5 pressure
modulator valves configuration, with the tag axle
having two sensors, but only one Pressure
Modulator Valve. In this case, the PMV controls
both wheels on the tag axle. The tag axle wheels
would receive equal brake pressure, based on
the wheel that is currently experiencing the most
wheel slip.
FIGURE 52: M-40QR PRESSURE MODULATOR VALVE
Maintenance
NOTE
On older vehicles, when replacing for the first
the modulator
time older
modulator
newer M-40QR
to replace both left and right valves on the
vehicles drive axle or front suspension.
Modulator valve model can be easily identified
by their different side cover and exhaust section.
48 PA1621 Maintenance Manual All Series | Revised June 2020
the
valve M-32QR by
valve, it is important
Mixing valve type on the left and right sides of
the vehicle may result in slight pull to one side
when braking.
Maintenance, removal
information of this valve is supplied in Bendix
booklet, found on your Technical Publications
USB flash drive, under reference number
SD-13-4958.
23.3 ABS WITH ELECTRONIC STABILITY
CONTROL (ESC)
Overview
Bendix ESC stability system reduces the risk of
rollovers, jackknifing and other loss of control.
ESC features include Roll Stability Program
(RSP) and Yaw Control. During operation, the
ECU of the Bendix ABS system constantly
compares performance models to the vehicle's
actual movement, using the wheel speed
sensors of the ABS system, as well as lateral,
yaw, and steering angle sensors. If the vehicle
shows a tendency to leave an appropriate travel
path, or if critical threshold values are ap-
proached, the system will intervene to assist the
driver.
Roll Stability Program
Bendix RSP, an element of the overall ESC
system, addresses rollover conditions. In the
case of a potential roll event, the ECU will
override the throttle and quickly apply pressure
at all wheel ends to slow the vehicle. The level of
braking application during an RSP event will be
proportional to roll risk.
Yaw Stability
and installation