Principles Of Operation; Maintenance; High-Buoy - Pressure Regulator; Adjustment - PREVOST H3-41 Maintenance Manual

be put into service during normal vehicle
operation.
10.1

PRINCIPLES OF OPERATION

The rear high-buoy system is added over the
front kneeling (with front high-buoy). The front
end uses the same valves as the front kneeling
(with front high-buoy). A solenoid valve is added
to send air to the double shuttle valves for the
rear end. It uses the same dash switch as the
kneeling.
UP:
The air coming from the control valve flows
through double shuttle valves, to supply air
springs. The double shuttle valves prevent height
control valves from releasing air from air springs.
DOWN:
The control valve, on the dashboard, cuts off air
supply, so the double shuttle valves allow height
control valves to accomplish their function.
Height control valves release air from air springs
until suspension returns to its normal position.
10.2

MAINTENANCE

Refer to the air system schematic diagram
"OPT. FRONT KNEELING WITH REAR HIGH-
BUOY COMBINATION.
10.3 HIGH-BUOY – PRESSURE
REGULATOR
The H series vehicles pressure regulator is
located on ceiling of the spare wheel and tire
compartment and is accessible through the
reclining bumper. On X series vehicles, the
regulating valve is located in the front service
compartment. This valve should be adjusted to
90 psi (621 kPa).

10.3.1 Adjustment

1. Before turning on system air pressure,
release jam nut (2, Figure 42) then turn
regulator adjustment
clockwise until the load is removed from the
regulating spring.
2. Turn on system pressure.
handle counter-
PA1621 Maintenance Manual All Series | Section revised October 2018
SECTION 16 : SUSPENSION
3. Turn regulator adjustment handle clockwise
until the desired outlet pressure is reached.
4. To avoid minor readjustment after making a
change in pressure setting, always approach
the desired pressure from a lower pressure.
When reducing from a higher to a lower
setting, first reduce the pressure at a lower
pressure, and then increase it to the desired
level of pressure.
5. Tighten jam nut (2,Figure 42) to lock
pressure setting.

10.3.2 Disassembly

1. Shut off inlet pressure and reduce pressure
in inlet and outlet lines to zero. Turn
regulator adjustment handle (1, Figure 42)
counterclockwise until all load is removed
from regulating spring. Regulator can be
disassembled without removal from air line.
2. Disassemble regulator in accordance with
the item numbers on the exploded view.
Torque Table
Item
3 (Screw)
17 (Bottom plug)

10.3.3 Cleaning

1. Clean parts with warm water and soap. Dry
parts and blow out internal passages in body
using clean, dry compressed air.
2. Inspect parts. Replace those found to be
damaged.
Value
25-35 lb-in (2.8-3.9 Nm)
20-25 lb-in (2.3-2.8 Nm)
51