Monaco DIPLOMAT 2004 Owner's Manual page 367

Accessory air items are other pneumatically operated items such as the
air horns. The accessory air items operate only when air tank pressures
exceed 65 psi. This is done with pressure protection valves. Should an accesso-
ry air item fail, the pressure protection valve (PPV) reserves the remaining air
pressure of 65 psi for braking. This will leave the motorhome with one air tank
fully charged for safety back up.
In another situation, whereby all compressed air has escaped from the rear
air tank, a pneumatic back-up safety valve is installed. This is the safety
inversion valve. The inversion valve senses the absence of rear air tank
pressure. In this case the inversion valve will allow the operator to make a
modulated spring brake application, made in conjunction with the emergency
spring brake relay valve. The inversion valve allows the front air tank
pressure to recharge the rear brake chambers after the modulated spring
brake application has been made. This back-up system implements use of all
the brakes, allowing the operator to bring the vehicle to a safe stop. In case
of all compressed air charge escaping from the front air tank, the operator
will still have full use of the rear brakes.
The Pac Brake exhaust retard system is an auxiliary braking device that is
attached directly to the engine turbocharger. The exhaust brake operates by
using a dash switch. The dash mounted switch will operate the exhaust brake
when dash switch is "ON" and throttle is "RELEASED."
When the exhaust brake is activated, a flapper inside the exhaust brake
moves and restricts the flow of exhaust gases. This causes an increase of
exhaust pressure within the engine. Increased exhaust back pressure quickly
slows the engine speed resulting in powerful engine braking action. When
the exhaust brake is activated, the amount of engine braking power
developed is related to engine speed (RPM). When an exhaust brake
application is made, the engine braking affect increases with higher engine
RPM. The exhaust brake is wired to the electronically controlled
transmission. When the exhaust brake is activated going down a hill, it will
help control road speed or sufficiently slow the road speed until the Allison
Transmission will automatically downshift to the next lower gear.
Downshifting automatically occurs from high gear down to second gear.
Certain road conditions and engine speeds may require the transmission be
manually shifted down in order to generate adequate engine RPM and
increase the engine brake effect.
NOTE: The brake lights will illuminate while the PAC
Brake is applied.
NOTE: The cruise control system cannot be activated with
the exhaust brake switch in the ON position.
CHASSIS INFORMATION
DIPLOMAT 2004
EXHAUST BRAKE
090392
10 • 367