PREVOST GKN AXLES LIMITED KIRKSTALL DIVISION, Руководство по обслуживанию

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Section 16: SUSPENSION
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6. SUSPENSION AIR SYSTEM
6.1 Description
The suspension air system has its own air reser-
voir (accessory tank) which is located above the
front axle. Pressurized air from the main tank (wet
tank) flows through a pressure protection valve
(PR-2) installed on the accessory air tank, then
flows to the accessory air tank.
The pressure protection valve (PR-2) controls the
pressure at which compressed air would be deliv-
ered to the accessory air tank. The valve remains
closed until a preset pressure is reached (ap-
proximately 75 psi (517 kPa)). It then opens and
passes air out the delivery port.
The main use for this valve is to protect the main
air system by ensuring at all times a sufficient air
pressure in the main system (i.e. air delivered to
the accessories will be shut off in case of a de-
crease in pressure).
Another protection valve (PR-2) is installed on the
manifold block, and insures at all times a minimum
pressure of 75 psi (517 kPa) in suspension air
system in the event that a pressure drop occurs in
either the suspension air system or accessory air
system. This valve is located in the steering com-
partment
Maintenance and repair information on the pres-
sure protection valve is supplied in the applicable
booklet, annexed to Section 12, "Brakes and Air
System" under reference number SD-03-55.
6.2 Inspection
The following inspection should be performed at
established service inspection periods. Performing
these procedures will allow substandard perform-
ance to be discovered before the condition be-
comes bad enough to cause operator complaints
and failure on a run.
1. Visually inspect the suspension air lines for
evidence of chafing on metal parts or other
damage.
2. Visually inspect the air springs for cracks,
abrasion or other damage.
3. Replace any parts found to be damaged.
6.3 Air Line Test
With the main air system at normal operating
pressure (95 - 125 psi (655 - 860 kPa)), coat all
suspension air line connections and air spring
mountings with a solution of soap and water. Air
leakage will produce soap bubbles. Any leak
found must be corrected as no air leakage is per-
missible.
6.4 Air Tank Maintenance
Refer to Section 12, "Brakes and Air System"
under paragraph "2.2 Maintenance" for complete
instructions on air tank maintenance.
7. SUSPENSION HEIGHT
ADJUSTMENT
The flow of pressurized air from the accessory air
tank to the air springs is controlled by three height
control valves. These valves are mounted to the
subframe and connected to the axles through an
arm and link connection. This connection allows
the valves to apportion air pressure in the springs
to the vehicle load, maintaining normal ride height.
Immediate response height control valves in-
crease or decrease the air pressure in the sus-
pension system as required. One height control
valve is located at center of front axle, and regu-
lates air to front axle air springs in order to main-
tain the vehicle at the required height. Two are
located at the drive axle, one on each inner side of
rear wheelhouse. Refer to figure 11.
FIGURE 11: HEIGHT CONTROL VALVE
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