Section 16: SUSPENSION
PA1562
41
2. Assemble the regulator as shown on the
exploded view.
Torque Table
Item Torque in lbf-inch (Nm)
3 (Screw) 25-35 (2.8-3.9)
17 (Bottom plug) 20-25 (2.3-2.8)
11. LOW-BUOY SYSTEM
The purpose of the low-buoy system is to lower
the whole suspension by about 4” (100 mm) in
order to reduce the overall height for low
clearances. This system can be put into service
during normal vehicle operation.
11.1 PRINCIPLES OF OPERATION
On X3 coaches, the rear low-buoy is added over
the front kneeling system. The control valve on
the left console panel sends an electric signal
from its pressure switch to control the front
suspension as if kneeling. It also removes air
from a relay valve that exhausts air supply to all
leveling valves and the quick release in the rear
section. Air from the rear suspension can then
be depleted through the check valve-quick
release assembly.
Down:
The control valve, on the L.H. control panel, cuts
off air supply, so air is released from air springs.
A relay valve prevents height control valves from
supplying air springs.
Up:
The control valve, on the L.H. control panel,
supplies air to close the passage between both
the delivery and supply ports. A relay valve
opens and provides air springs until the
suspension reaches the normal ride height.
11.2 MAINTENANCE
Refer to the air system schematic diagram “Opt.
Front Kneeling With Rear Low-Buoy
Combination” annexed at the end of this
Section.
12. TROUBLESHOOTING
Condition Cause Correction
Bellows deflate over time 1. Defective check valve assembly.
2. Defective exhaust valve
assembly.
3. Leak in air line and/or bellows.
4. Defective valve cover, rubber
O-rings or gasket.
1. Replace check valve assembly.
2. Replace exhaust valve
assembly.
3. Replace air line or bellows.
4. Replace valve cover, O-rings or
gasket.
Bellows raise to full
height and fail to exhaust
air pressure
1. A clogged exhaust screen in
height control valve assembly.
2. A combination clogged exhaust
screen and defective air inlet
valve assembly.
1. Remove and clean screen.
2. Clean exhaust screen and
replace air inlet valve assembly.
Erratic valve action 1. Dirt or foreign matter in the air
valve lever chamber.
2. Defectives valves.
1. Remove valve cover and blow
out dirt. Install cover using new
gasket.
2. Overhaul height control valve
assembly
Vehicle body fails to
level to satisfactory ride
height
1. Improper height control valve
overtravel lever adjustment
1. Adjust lever as directed.
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