Here at the Air
Lift Company, we understand that air suspension systems are
technically sophisticated. The good news is that once you
understand the fundamentals, your ability to properly operate
and maintain your air suspension system is assured.
Our policy of educating the consumer is consistent with our
value-added approach to customer service, and is based on
our philosophy that an educated consumer is a confident one.
Please feel free to review this FAQ page. We have filled it
with component and system descriptions, information on basic
air suspension operation, and lessons learned. We think that
you'll find the information useful.
Air Suspension Basics
The basic air suspension system comprises a
compressor, storage tank, air springs, lines and fittings,
and a control mechanism. When integrated, these components
constitue the vehicles' primary suspension system, and allow
for adjustable ride height by changing air pressure, which
alters the air spring load and rate characteristics.
For our purposes, the most important consideration is adjustable
ride height. Contemporary sport truck, custom, and street
rod styling mandates a lowered stance, while discriminating
enthusiasts demand technical sophistication. Easy Street air
suspension systems satisfy both requirements. Another important
consideration in this conversion is proper shock absorber
fitment. Easy Street systems include all the bracketry need
to relocate the shock absorber to the optimum position. As
air suspensions become more popular, there is an increasing
emphasis on radical rear suspension modifications, including
frame "notching" and the employment of 3 and 4 link
trailing arm axle locating systems, such as in our 88-98 Chevy/GMC
rear kit (75610). Easy Street systems are designed to allow
for maximum suspension travel "out of the box".
In addition, we offer optional bolt-on and weld-on C-notches,
dropped spindle and disc brake conversion kits, and remote
control. The following air suspension FAQ and component descriptions
provide information relative to basic air suspension design
and performance. If you have a specific question, or are interested
in additional information, please email or call us at 1-800-248-0892,
ext. 249 or ext. 252. FAQ's
How does an air spring work?
An air spring employs a flexible membrane to
capture compressed air. The “spring” is the air, and an air
spring takes advantage of the physical properties of air that
allow it to be compressed. As the bag is compressed, the air
pressure in the bag increases, forcing the bag to seek a return
to its static height, or to “rebound”, similar to a steel
spring.
How is an air spring rated?
The spring load and rate characteristics of
an air spring are determined by its physical configuration,
and manipulated by air pressure.
Spring load is the amount of weight required to compress
a spring to a given height, at a given pressure.
Load is expressed in lbs. Spring
rate is the amount of weight required to compress the spring
one inch, and is expressed in lbs./in. Therefore, the spring
load determines how much the spring can support at a given
height, and the spring rate determines how much the spring
will compress as the loading increases.
What do the terms
convoluted, rolling lobe, and tapered sleeve mean?
Convoluted refers to an air spring constructed
with one, two, or more convolutions, which are defined by
the end plates and equally-spaced dividing rings which have
a lesser diameter than the rubber membrane. This construction
forms a bellows, or “donut” shape. Rolling lobe
and tapered sleeve air springs are cylindrical in construction.
Typically sleeves have a lower rate curve than bellows,
which provides a more comfortable ride when carrying for
lighter loads.
How
durable are air springs?
Air springs are extremely durable and will
last for years, if installed properly and in an appropriate
environment. Air springs fail as a function of abrasion
(contact with suspension and frame components), operation
under extreme over or under-inflation conditions, or gross
misalignment of the air spring.
Generally, a minimum of one inch of
clearance between the bellows and any other structure, when
the air springs are fully inflated, is necessary. Air springs
should never be subjected to prolonged use at maximum pressure,
and a minimum of approximately 20 psi is required to prevent
internal chafing of the air spring.
A physical stop, such as a jounce bumper,
is necessary to prevent the bag and/or suspension from bottoming
out, in the unlikely event of a line or bag failure.
How
is an air suspension system typically configured?
An air suspension system starts with an
onboard air compressor and a reserve tank. The onboard compressor
is necessary to supply the compressed air, and the storage
tank stores the volume of air that is required to inflate
the springs.
From the storage tank, air is routed to
solenoid valves, and then to the air springs, by distribution
lines. Available in 1 /4", 3 /8", and even 1 /2"
OD’s, flexible thermoplastic tubing is the material
of choice.
The most common fittings are push-to-connect
(PTC). PTC fittings are reusable, although the tubing should
be trimmed back occasionally so as to present a fresh surface
for sealing.
What
determines the flow rate of a system?
The flow capacity of a given air suspension
component is called the Cv factor. Cv (“see-sub-vee”)
is a coefficient based on the number of gallons per minute
of water, which could pass through the part with a one psi
pressure differential between the inlet and cylinder ports.
In a pneumatic system, the component that has the lowest
Cv determines the overall flow capacity of the system. Increasing
airline size beyond the flow capacity of the other components
has no net effect. Airline size is a limiting factor ONLY
when it represents the smallest orifice in the system.
What
is a solenoid valve?
A solenoid valve is an electrically actuated
valve. Available as individual units, or mounted as a group
to a base, solenoids offer high flow rates, quiet reliable
operation, and a number of plumbing alternatives. Quality
solenoids are manufactured from brass or hard-anodized aluminum
(extruded aluminum bodies degrade in the harsh under-car
environment), are rebuildable, and usually advertised as
“bubble-tight”.
Is
it possible to combine air springs with other lowering components?
Air springs are physically compatible with
dropped spindles, and are commonly used in conjunction with
dropped spindles. By definition, air springs are a direct
replacement for coils. Most air suspension manufacturers
design their systems to ride at a height that is consistent
with the OEM spring height.... therefore, when driving,
the vehicle assumes a typical “dropped spindle”
attitude. However, air suspensions take advantage of the
fact that you can reduce height, beyond that offered by
the spindle, as a function of deflating the air spring,
when you are posing.
Which brings up a very important point….
although air springs allow for the vehicle to be lowered,
they are not intended for lowering the vehicle on-the-fly,
or for operating the vehicle in an attitude other than that
which is required to maintain proper alignment when the
vehicle is in motion.
Is
alignment different with an air suspension?
For the purposes of alignment, an air spring
should be treated like any other spring: establish ride height
(driving height) and align the vehicle at that point. Yes,
the alignment changes as the suspension moves through its
travel, but this is true of any suspension. Alignment problems
with air suspensions are usually a result of driving the vehicle
at other than alignment (driving height) pressure.
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