warranties in the industry.

TIP #2

Look for fully integrated systems (suspension, axle and
brakes). With a truly integrated system, each element
is designed and tuned to work together for optimum
performance. Not only does this ensure the system will
perform well, but it keeps weight down and offers
the convenience of a single source for warranty and
technical support.

Hendrickson offers the finest integrated air suspension
systems available. In 1995, Hendrickson introduced
INTRAAX ®, the first integrated trailer air suspension,
axle and brake system. Two years later, Hendrickson
introduced VANTRAAX ®, a tandem air slider system
designed for dry vans and reefer trailers. Hendrickson
continued to integrate more components into a
single suspension system with the introduction of
proprietary wheel-end packages. Launching a new
era of virtually maintenance free suspension systems,
Hendrickson’s leading warranties protect everything
from the integrated suspension, axles, air springs and
shock absorbers to the brakes and wheel-ends.

TIP #4

Look for systems providing minimal maintenance requirements.
This includes a minimum number of fasteners, bushings
and other wear items. Check for fastener re-torque
requirements — again, the fewer the better.

Hendrickson suspensions are designed with very
few wear items to minimize maintenance. In many
applications, our TRI-FUNCTIONAL® Bushings last
the life of the trailer. Unlike most other suspension
brands, our current designs have no re-torque
requirements. With Hendrickson suspensions,
routine maintenance is generally as simple as
a visual inspection.

TFII

TFIII

TRI-FUNCTIONAL® Bushings

10

AIR SUSPENSIONS

5

TIP #5

As for those items that are most likely to need replacing over
time, such as air springs and shock absorbers, check to see
how quickly and easily they can be replaced. Check for easy
access to those parts in the aftermarket.

Maintenance on Hendrickson suspensions is very easy,
thanks to thoughtful designs. Hendrickson parts are
very accessible in the industry. This is due to the vast
number of distributors that stock Hendrickson Genuine
Parts and the large number of suspension units we
have operating around the world.

7

TIP #7

Always consider the application requirements when
spec’ing a suspension system. Capacity and duty cycles
will help determine what suspension system rating will
be needed. Over or under-spec’ing can cause problems:
over-spec’ing a suspension adds unnecessary cost and
weight, while under-spec’ing a system can lead to
premature wear and suspension damage as well as ride
quality and control problems. Know how the vehicle will
be used. Lots of empty backhauls could make a lift kit,
such as Hendrickson’s UBL™ UNDER BEAM LIFT™ a viable
option to reduce tire wear.
Hendrickson’s INTRAAX ® and VANTRAAX ® suspension
families can support a variety of application
requirements, from standard hauling to extreme
heavy-duty, from tankers to flatbeds, from dumps
to vans.

6 8

TIP #8

TIP #6

Be sure to consider suspension system weight. This is
especially important if trailers tend to gross out in weight
rather than max out in cube space. Even if you are not
spec’ing for heavy loads, a lightweight suspension can help
improve fuel efficiency and improve flexibility in accepting
backhaul loads.

Hendrickson delivers some of the lightest air
suspensions in the industry. A lower suspension
system weight will help maximize payload and
add to fuel efficiency.

Look for features and options that make a system easier
and more efficient to use. Slider pin-pull assist mechanisms,
pivot connections that facilitate axle realignment and dock
walk prevention devices are popular. They can save fleets
headaches by improving operating efficiency.

Hendrickson integrated suspension systems feature
value-added items such as QUIK-DRAW ®, QUIK-ALIGN ®
and SURELOK®. These features help improve vehicle
efficiency and add to driver satisfaction.

INTRAAX® A
­ ANLS
­VANTRAAX® HKANT

UNDERSTANDING AIR SUSPENSIONS

11

UNDERSTANDING

UNDERSTANDING

TIREMAAX

®

The majority of truckers agree that tires represent the
most important maintenance item on a trailer. The simple
activities of maintaining proper tire pressure and checking
for irregular wear can extend tire life substantially, reduce
maintenance and save thousands of dollars annually.
Tires remain the number one reason for trailer breakdowns
weighing in at 48 percent of 63,789 road calls, according to a
recently published survey. The Technology and Maintenance
Council (TMC) reports a study of tire pressures on 35,128
vehicles, which revealed that 56 percent of vehicles are
more than 5 psi off target pressure and more than 7 percent
are under-inflated by 20 psi or more.
In terms of fuel economy, an industry rule of thumb
attributes a 1 percent
reduction in miles per
gallon for every 10 psi
under the specified inflation
pressure. Truckers know the
pitfalls of improper tire
inflation: reduction in tread
and casing life, as well as increases in rolling resistance,
which burns more fuel and creates a poor ride.

Even properly maintained tires are subject to air loss
through punctures, road hazards and changes in ambient
temperature. Irregular tread wear can develop when the
pressure of joined dual tires differs by as little as 5 psi.
Without enough air, tires flex too much causing excessive
heat, rolling resistance and corresponding drop in fuel
economy. Tires wear unevenly and become more prone
to damage from road hazards and curbing.
Tire disintegration, exemplified by zipper rips and the
dreaded “alligators” (black shards of rubber seen along
highways), presents more extreme examples of problems
caused by under inflation.
Fleet managers and owner operators continue to struggle
with finding ways to maintain proper tire inflation, when
simply putting a little air in the right place at the right time
can save a lot of effort and expense on trailer operations.

THE HENDRICKSON ADVANTAGE
Hendrickson brings a breath of fresh air to tire pressure pitfalls with its TIREMAAX®
tire inflation systems. Two versions of the popular system are available. TIREMAAX CP
features a simple mechanical design, while TIREMAAX PRO is an advanced automatic
tire pressure control system that actively controls tire pressures by inflating or relieving
air from tires when necessary. TIREMAAX uses the trailer air supply to maintain tire
pressures to a preset level. This can help minimize costly, excessive tire wear and improve
productivity and fuel mileage. The system detects changes in pressure and responds by
directing air to an under-inflated tire. An indicator light alerts the driver to system status.

12

AIR SUSPENSIONS
With the TIREMAAX® CP system, customers enjoy the
simplicity of a continuous pressure system. With robust
components and no electronics, transducers or pressure
switches, TIREMAAX CP is easy to maintain.
The revolutionary TIREMAAX PRO shares all the features
and benefits of the CP system; whereas TIREMAAX CP can
only inflate a tire that drops below the recommended psi,
TIREMAAX PRO addresses the issue of over-inflation.
By responding to changes in ambient temperature,
TIREMAAX PRO has the capability to relieve
air from a tire that is
over-inflated. PRO also
constantly pressurizes
and equalizes trailer
tires, reducing scrubbing between duals and
improving tire life.
With both TIREMAAX
systems, air travels from
the supply tank through
air lines inside the axle to
the wheel-ends, which
eliminates the need to
pressurize the axle tube
and neutralizes a source
for wheel-end contamination. A rotary union that is
integrated into the hubcap allows air to flow from
a non-rotating axle spindle to the rotating hubcap
fitting. Durable tire hoses connect the hubcap to
the valve stems.
All TIREMAAX systems are available with a signal light,
designed for installation in view of the
driver. It alerts the operator to system
status and maintenance activity.
Check valves prevent tire pressure
loss back through the system.

TIREMAAX® PRO
Controller

Manual fill and pressure checks may be accomplished
at the hose ends. TIREMAAX connects all tires to the trailer
air supply and may be combined with any of an extensive
array of wheel-end configurations and spindles available
on INTRAAX®, VANTRAAX® and ULTRAA-K® integrated
suspension systems and TRLAXLE® non-integrated axles.
Hendrickson TIREMAAX systems provide a cost-effective
approach to eliminate
tire pressure problems.
For additional information:
TIREMAAX PRO
Tire Inflation System —
L1199
TIREMAAX
Tire Inflation System —
L1017
TIREMAAX Tire
Inflation System
Installation, Service
and Troubleshooting
Procedures — T51002
Download current literature
at www.hendrickson-intl.com

TIREMAAX® CP
Controller

TIREMAAX® PRO

UNDERSTANDING AIR SUSPENSIONS

13

USER FRIENDLY

UNDERSTANDING

QUIK-DRAW

®

Drivers often struggle to reposition a slider under a trailer.
The net result is often unhappy, unproductive and
sometimes injured drivers. The most common reason for
this situation is difficulty in retracting the lock pins that
hold the slider in a given position on the trailer. Even if
the mechanical linkage used to retract the lock pins
functions properly, the pins can become jammed or
bound against the positioning holes in the trailer’s
body rails. The forces causing this binding can be due
to a number of reasons such as the trailer sitting on
uneven ground or the parking brakes being set while
the lock pins are pushed tightly against the front or rear
of the body rail holes.

moves the rig slightly in an attempt to center the pins in
the body rail holes. This action may have to be repeated
until a position is found that allows the pins to be pulled.
Particularly frustrating with a conventional mechanism,
a single jammed pin can prevent the handle from being
pulled even if the other three pins are free to move.

To aggravate these situations still further, sometimes the
body rail holes wear grooves into the unhardened lock
pins creating a mechanical interlock between the lock
pins and the body rails.

Occasionally after repositioning a slider, a driver forgets
to re-engage the slider’s lock pins. When this happens,
the slider may violently thrust against the slider restraint
bar at the first braking. This can result in a damaged
slider, trailer or payload and possibly even the loss
of the slider from beneath the trailer. These types of
incidents present serious safety concerns as well as
impediments to driver productivity and satisfaction.

When this binding occurs, the driver may not be able to
exert enough force against the pull handle of the lock pin
retraction mechanism to disengage the pins. The driver
then goes back to the cab, releases the parking brakes and

Sometimes, in an effort to bypass this time-consuming
and inconvenient process, the driver will exert extra
effort against the pull handle in an attempt to force the
jammed pins free, risking back and shoulder injuries.
These injuries can result in lost time and worker
compensation claims.

THE HENDRICKSON ADVANTAGE
Hendrickson addresses these
concerns by tapping trailer air
power to make true fingertip
slider pin release a reality with
QUIK-DRAW®. With versions
for VANTRAAX® van and reefer
slider systems and INTRAAX®- SP
platform sliders, QUIK-DRAW
triggers with a simple pull of a knob.
QUIK-DRAW relieves drivers from the tugging, jerking and
hammering associated with releasing locked or jammed
slider pins. With pins released in seconds, slider repositioning

14

becomes faster and more efficient — getting rigs back
on the road sooner.
Standard on all VANTRAAX air slider systems, the patented
van-style QUIK-DRAW features actuators consisting of a
fabric-reinforced rubber tube. Fittings at each end attach
to the inboard ends of our slider’s hardened lock pins.
One actuator per axle controls the two lock pins and
the conventional mechanical linkage components are
completely eliminated. When the knob of the valve is
pulled, these unique actuators are pressurized by the
trailer’s compressed air supply.

AIR SUSPENSIONS
Once pressurized, the actuators increase in diameter
and shorten in length, exerting a powerful pulling force
— several times greater than most conventional mechanisms — to retract the pins. If the pins are free to move,
they all retract, and the slider can be repositioned.
However, even if one or more pins are bound, the actuators
continue to apply pressure. When the driver returns to
the cab to reposition the slider, movement of the trailer
above the slider will “jiggle” the jammed pins free, and
the actuators will retract those pins. The slider can be
repositioned without difficulty.

QUIK-DRAW allows drivers to disengage the slider’s lock
pins using only fingertip effort.

conventional mechanism have been eliminated in the van
version. Hendrickson makes the actuators from the same
sturdy material as an air spring and tucks
them inside the slider frame to protect
from road debris. The actuator
valve meets stringent durability
and environmental conditions
— operating in temperatures
to minus 40 degrees. The valve is
mounted in a recessed manner on a
bracket with a shield to protect the
valve from road debris, snow and ice.
An air-activated QUIK-DRAW comes standard on
INTRAAX® -SP platform slider systems featuring a proven
air chamber actuator with automatic reset. The chamber fits
neatly inside the slider cross member for added protection.

What this means to the fleet owner and
owner operator:

As an additional safety feature, QUIK-DRAW® automatically
resets pins with the release of the trailer parking brakes.
Hendrickson equips the valve of the VANTRAAX® version
with an air-pilot reset plumbed to the parking brake circuit.
If the driver forgets to reset the lock pins before driving
away, simply releasing the parking brake dumps air from
the QUIK-DRAW actuators, shifts the valve knob to the
“pins engaged” position and allows the coil springs to
reset the pins in the body rails. Even if the lock pins do not
align perfectly with the body rail holes, the pressure of the
QUIK-DRAW coil springs pushing the pins outward will be
maintained until engagement occurs. Thus, the pins will be
forced out through the next available set of body rail holes
as the slider moves past.
The durability and reliability of the QUIK-DRAW system
enhances its simplicity. Most moving parts of a

1. Improved driver productivity - QUIK-DRAW
permits a driver to efficiently reposition a slider
with a single operation — even if the lock pins
jam — eliminating the need for multiple trips
between the cab and trailer.
2. Enhanced driver satisfaction - Drivers can easily
disengage lock pins. Simply pull a valve and pins
will retract - no tugging, jerking or hammering.
3. Automatic reset - In the event that a driver
forgets to re-engage the lock pins, QUIK-DRAW
automatically resets them when the trailer brakes
are released.
4. Reduced weight - The QUIK-DRAW van style is
the lightest in the industry compared to other lock
pin release mechanisms.
For additional information: QUIK-DRAW Flyer — L628
Download current literature at www.hendrickson-intl.com

UNDERSTANDING AIR SUSPENSIONS

15

CONTROLLING

UNDERSTANDING

Ride Height
Fleets and owner operators specify trailer air suspensions
for many reasons, including smooth ride regardless of
payload, minimal cargo damage, load equalization and
flexibility to haul a wide variety of freight. To realize these
benefits, the trailer suspension must be set at its proper
ride height.
Ride height is defined as the
measurement from the
suspension-mounting surface
(the bottom of trailer frame
or slider box) to the center
of the axle (figure 1). Air
suspensions are designed to
operate at specific ride heights.
Maintaining a suspension’s
proper ride height is a critical
element of air suspension trailer
performance. The heart and soul of any air suspension
system is the height control valve (HCV). The HCV maintains
the trailer at its designed ride height by automatically adding
and exhausting air to the trailer’s suspension to compensate
for changes in the trailer’s load.
Operating an air suspension at an incorrect ride height
can create improper load equalization, reduce ride quality,
damage cargo / vehicle and result in premature suspension
and component wear. Air suspensions set too high will
cause shocks and air springs to be over extended.

Trailer Frame
Height
Control
Valve

Ride
Height

Axle

Figure 1

A suspension with a ride height set too low experiences
a harsh ride due to the constant thumping against the
air spring bumpers.
When height control valves and ride height settings
are improperly adjusted or otherwise tampered with,
premature component wear may occur. To operate
properly, suspensions must ride at their specifically
designed ride height. While poor ride, premature
component wear or appearance might be signs of
improper height settings, avoid changing ride height
until a careful measurement is taken. This is the only
way to be assured of proper ride height settings. The
correct ride height will allow for the proper amount
of suspension travel, keeping the trailer performing
at peak operating efficiency.

Precise air flow regulation delivered
To deliver the ride quality and other benefits truckers
expect, trailer air suspension systems require precise
air flow management — a key element perfected by
Hendrickson’s standard height control valve (HCV)
and integral HCV with automatic dump valve.
Spec’d from the OEM on new vehicles or through the
aftermarket, Hendrickson’s HCVs offer superb designs
to keep your trailers at correct ride height.

16

Using an advanced Shear-Seal® design to ensure
accurate air flow, Hendrickson HCVs deliver superior
performance and durability. A precise, highly repeatable dead band and high air flow with a proportional
response optimize ride height control to deliver superior
ride quality, while prolonging air spring and shock
absorber life.

AIR SUSPENSIONS
Specially designed and tested for optimum performance
with Hendrickson air suspensions, our HCVs help you
maintain outstanding load stability over the road. In
addition, Hendrickson HCVs minimal dead band and
high flow rate provide compatibility with on-board
trailer weight scales.

All Hendrickson HCVs:
• Operating pressure
— 130 psi (9 bar) maximum
• Operating temperature
— -40°F to +150°F (-40°C to +65°C)
• Maximum flow rate
— 350 L/Min (12.4 cfm)
• Delivery ports
— 1/4-inch NPT fittings
— Dual delivery ports
• Maximum handle movement
— +/- 75° for fill or exhaust
• Options
— Air fittings
— Mounting brackets