Holiday Neptune 2004, Owner'S Manual

Page: 355 / 416

CHASSIS INFORMATION --- SECTION 10 • 355
NEPTUNE 2004
10
Three height control valves (HCV) inflate or deflate air springs, maintaining
proper suspension height throughout the load range. Two valves are used at the
rear drive axle to control rear suspension height and left or right tilt of the
motorhome. One valve controls front suspension height. Height control valves
mount to the main frame of the motorhome, above the axles, with a linkage rod
connecting the valve to the axle.
Ride height is a pre-determined setting of the relationship between the axles
and frame to optimize operation of the air spring and other chassis systems.
Leveling valves are mounted to the frame of the chassis, with a rod linkage
connecting to the axle. Ride height can be adjusted with the rod linkage. Actuating
components inside the valves are oil dampened to reduce valve reaction to
momentary suspension bounce and rebound. When a constant suspension change
occurs, such as a load change or weight transfer through a sustained corner, the
valve reacts, adding or purging air from the air springs accordingly in order to
help maintain proper ride height. Proper ride height specifications for the air
suspension is 6 ½" Front and 8" Rear, plus or minus ¼". This measurement is
taken from the top side of the top plate to the bottom side of the bottom plate of
the air spring.
The air springs mount between the axles' frame assembly and the two main
frame rails. Air spring support plates mount to the main frame rail and the axle
frame assembly. It is extremely important to always operate the vehicle at the
designed ride height. The air spring must maintain a specified distance between
the mounting plates. Other than specified distance between the plates not only
compromises ride quality and handling, it adversely affects shock absorber travel,
drive shaft angle and various other running gear components.
Should it become necessary to check the suspension ride height, start with the
motorhome on a flat level surface. The air system must be fully charged with the
suspension normalized at ride height. Measure the distance between the mounting
plates of the air springs. Specified distances may vary plus or minus ¼". Make
adjustments in small increments. Small offset adjustments to the rear valves may
be necessary to compensate for slight tilt. Example: Adjusting the curbside rear
height control valve up will pivot the roadside front corner down.
NOTE: Drive shaft angle is affected by the suspension ride
height. Improper drive shaft angle can damage suspension or
shorten the life of universal joints. Shock absorbers and air
springs are in travel centers at proper ride height.
RIDE HEIGHT
VALVES