Chassis - Introduction; Air Supply System - Holiday Rambler Imperial 2008 Owner's Manual

CHASSIS INFORMATION — 10

CHASSIS - INTRODUCTION

This section contains information and
instructions regarding various components of
the motorhome chassis. Follow the guidelines
and procedures to help understand and operate
the motorhome. Complete instructions for the
engine and transmission are located in their
respective operator's manual included in the
Owner's Information File Box.
WARNING:
When welding is involved for
motorhome repair or modification,
only qualified, experienced technicians
should weld on the chassis. Improper
welding procedures and materials
may weaken the assembly or result in
damage that is not obvious and may not
cause an immediate problem or failure.
Unauthorized modifications or repairs
to the chassis could result in a forfeiture
of warranty coverage.
DANGER:
Due to the sensitive nature of the
electronics on the chassis, the following
precautions are required to protect
electrical components in the motorhome
chassis:
1. Disconnect the (+) positive and (-)
negative battery connection.
2. Cover electronic control components
and wiring to protect from hot
sparks.
3. Disconnect the terminal plugs from
the engine Electronic Control Unit,
located on the curbside side of the
engine block.
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4. Disconnect all the plugs from the
transmission Electronic Control Unit,
located in the storage bay between
the frame rails.
5. Disconnect the wiring from the
alternator.
6. DO NOT connect welding cables to
electronic control components.
7. Attach the welding ground cable no
more than two feet from the part to
be welded.
The Roadmaster chassis is a semi-monocoque
design using all tubular steel. The semi-
monocoque design provides greater structural
integrity and overall uniform stress distribution.
Incorporated in the Roadmaster chassis is the
exclusive cushion air glide suspension system
using eight outboard and two inboard mounted
air springs and ten Bilstein shock absorbers.
The location of the air springs and shock
absorbers combined with the semi-monoque
chassis provides the smoothest ride, best
handling and trouble free service while
delivering top notch drivability. The chassis has
a three-point hydraulic leveling system or an air
leveling system or both.
The front and drive axles are affi xed in the
chassis with trailing arms in a parallel four link
arrangement while the tag axle uses leading
arms. A panhard bar attached to the axle and
frame prevents side motion of the axle in the
chassis. The front and drive axles are mounted to
a wide platform H-frame that carries the coach
body on eight outboard mounted air springs,
four front and four rear. The tag axle uses two
in-board mounted air bags. Suspension bushings
require no lubrication for ease of maintenance.
Unlike suspension that uses springs, the air
2 00 8 I MP E R I A L
suspension system automatically maintains the
same attitude and ride height throughout the
entire load range.
The towing receiver is rated at 10,000 lbs.
towing weight and 1,000 lbs. tongue weight.
Tag located on curbside frame behind front wheel
and in generator compartment.

AIR SUPPLY SYSTEM

The air compressing system on the motorhome
includes a compressor, governor, dryer, front
tank and rear tank. The compressed air system
operates several items, including brakes,
suspension, air horns, air gauge and the stepwell
cover. The air system is charged by a gear
driven air compressor mounted on the engine.
As engine speed increases, compressed air
output increases. When the air is compressed,
heat is generated. Heat dissipates as the air
is discharged from the compressor. Moisture
condenses in the compressed air as it cools and
enters the air dryer to be fi ltered. The fi ltered
air charges the front air tank, which is divided
in to a wet and dry side. The compressed air
enters the wet side before entering the dry side.
A discharge line from the dry side of the front
air tank charges the rear air tank. Discharge lines
use in-line check valves to prevent a back fl ow
of compressed air.
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