Howard Power Center Steering

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Howard Power Center Steering | Manualzz
 RIVER CITY PRODUCTS, INC. |
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4 № |
_— HOWARD
RE PRECISIÓN STEER WHEEL |
MD. CONTROLSYSTEM™ J
Howard
Precision Steer Wheel
Control System™
SERVICE MANUAL
River City Products, Inc.
199 W. Rhapsody
San Antonio, Tx 78216
1-800-879-4277
Web Site
hpcss.com
10-31-03
DESIGN FEATURES
Booted End Rod
Push Pull
End Cap
ee
Pull Piston
Trim Solenoid
Trim Piston Trim End
Stop Block
Hydraulic
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Po 20 vole End Cap
Push Piston
CYLINDER
Zero backlash power centering 6. Double wall construction
Infinite trim control Li High quality finish
High quality Parker seals 8. DOT hydraulic fittings
Shaft protection boot 9. Oil filtration screens
Preloaded rod end bearings for “0”
slack
10. Continuous duty trim solenoid
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Heavy wall aluminum construction
Easy to read fluid level sight glass
High quality Parker seals
Rugged Nitrile bladder
Automatically expels moisture
ACCUMULATOR/COMPRESSOR
PANEL
8. Continuous duty solenoids
9. Quality Bosch relays
10. Dependable Thomas Air
Compressor
11. Airdryer/filter moisture trap
Automatically charges & discharges 12. DOT hydraulic fittings
air
Multiple mounting brackets
13. Galvanized mounting panel
14. Color coded wiring harneses
PUSH TO TRIM BUTTON SYSTEM PRESSURE GUAGE
AIR REGULATOR MASTER ON-OFF SWITCH
CONTROL WITH CIRCUIT BREAKER
CO Г, РАМЕ RIZON
BRO a Lid CONTROL PANEL IN
VERTICAL ORIENTATION]
CONTROL PANEL
Precision molded ABS housing 4, Push button trim control
and face
J. Easy to read air pressure gauge
Combination master switch/circuit
breaker 6. Multiple mounting position
hardware
Easy to turn air pressure regulator
7. Lighted for night operation
SAFETY
Power Steering Safety Switch additional method of turning the
automatically cuts the system off system off.
in the event power steering
fails. 4. When unit is off, there is no
effect on the conventional
Master Switch/Circuit Breaker steering system.
shuts unit down manually or
automatically in the event of a >;
short circuit.
Carefully engineered heavy duty
centering cylinder mounting
brackets provide maximum
Air Pressure Regulator can be
turned down to “0” PSI as an
“holding strength” during Steer
Wheel Blowout.
10-22-03
4
Table of Contents
TOPIC PAGE
s DESIGN FEATURES N are
* DEFINITIONSDISCLAIMER + ..............
“INTRODUCTION сс ee
* HYDRAULIC & AIR SCHEMATIC (with Kit Compressor) ..............
* ELECTRICAL SCHEMATIC (with Kit Compressor) ..............
« ELECTRICAL SCHEMATIC (with Kit Compressor)- 24vdc ..............
* GENERAL DESIGN € OPERATION Ls
* SUB ZERO “WINTER” OPERATION eens
« MAINTENANCE CHECK LIST = ..............
s GHECRINGELUIDLEVEL: Restan rezar
« TROUBLE SHOOTING ~ TECHNICAL = = = cscs
SETTING TRIM = TIE ROD CLAMP. = = seein
* SETTING TRIM- SLIDER PLATE MOUNT ..............
* TOOLS & MATERIALS REQUIRED FOR SERVICING ..............
¢ TOROUE CHARTS asses
ADDITIONAL STEERING SYSTEM MAINTENANCE TIPS ..........
« ADDITIONAL STEERING TIPS = Lessons
o FINAL INSPECTION. = se
NOTICE: FAILURE TO FOLLOW THE INSTALLATION
INSTRUCTIONS IN THIS MANUAL, OR FAILURE TO
INSTALL THE COMPLETE KIT FOR SPECIFIC CHASSIS
WITH ACCEPTABLE WORKMANSHIP, MAY RESULT IN
VOIDING THE WARRANTY.
DEFINITIONS
NOTE!: A “Note” gives key information to make a procedure easier or
quicker to follow or understand.
CAUTION!: A “Caution” refers to those procedures that must be followed to
avoid damage to the vehicle or the steering system.
WARNING!: A ” Warning” refers to those procedures that must be followed for
the safety of the driver and the person installing, inspecting or
repairing the vehicle or steering system.
DISCLAIMER
The information contained in this Installation and Service manual is compiled with
due diligence and accuracy. However, nothing contained here-in should take precedence
over reasonable judgement pertaining to a proper installation.
The basic components of the HOWARD PRECISION STEER WHEEL
DIRECTIONAL CONTROL SYSTEM are manufactured to high standards. To achieve
the intended benefits of this product, we invite the installing agency to play a major role in
providing a professional high quality installation. In the event the Mounting Brackets or any
other component supplied with this kit are not applicable to the particular chassis being
worked on, please call CUSTOMER SERVICE at 1-800-879-4277. By teamwork between
the installation technician and our engineering service department, we will be able to solve
installation problems that may happen because of differences in chassis that have not been
noted before.
At River City Products, Inc. we are dependent on the installer for a quality end
product. We appreciate and thank you for helping to make PRECISION STEER WHEEL
DIRECTIONAL CONTROL work as it should, and to make heavy vehicle driving more
enjoyable and safer.
NOTE!: Field Modifications to mounting brackets are NOT recommended
without consulting River City Products’ Installation Service
Engineering.
INTRODUCTION
This service manual is an important guide for installing and servicing
the Howard PRECISION STEER WHEEL DIRECTIONAL CONTROL™
System.
The “General Design and Operation” section addresses the major
components of the PRECISION STEER WHEEL CONTROL System and
explains how they function together. The knowledge you acquire from
reviewing this section should assist you in solving any problem you
encounter when installing, servicing, or trouble shooting the system.
This manual also contains trouble shooting information and check
lists. With these, you can diagnose a problem without having to remove
any components from the vehicle. If you must service a system for repair
work, the check list will help you determine where the problem may be.
When necessry, reference will be made to the schematic diagrams
provided in this manual. As you gain experience in the installation, servicing
and trouble shooting of the Howard PRECISION STEER WHEEL
DIRECTIONAL CONTROL™ System, you may find that some information
in this manual could be stated more clearly and more completely. If so, let
us know about it. Don’t try to second guess the manual. If you have
questions about an installation, contact us. Installing and servicing this
system should be a safe, straight forward and productive proceedure.
Pay special attention to all NOTES!, CAUTIONS!, and WARNINGS!.
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GENERAL DESIGN AND OPERATION
SYSTEM DESIGN
CYLINDER
The centering and trim cylinder is
comprised of three inner cylinders and one
outer cylinder. The inner cylinders house
pistons, which allows the cylinder to function
in three modes. The trim end of the cylinder
1s fitted with a trim control box, which is
attached to the outer cylinder. A series of
check valves and solenoids control fluid flow
to and from the cylinder. The design is
such that the cylinder is self bleeding. The
centering end of the cylinder houses the
push-pull rod, which moves the push piston
and the pull piston off their shared piston
stop block. The trim shaft is connected to
ACCUMULATOR
This component is comprised of a
heavy duty aluminum body, an upper and
lower cast aluminum cap, two normally
open continuous duty solenoids, a polycar-
bonate oil level sight glass, a nitrile bladder,
and a combination moisture trap filter
assembly. D.O.T. fittings are used to
attach air and hydraulic lines to the
accumlator. Design is such that the charg-
ing and discharging of the accumulator is
done automatically each time it 1s turned on
and off. Venting design of the accumulator
prevents overfilling the oil reservoir.
10
the trim piston which is housed and contained
by the trim cylinder. The complete cylinder
is mounted to the vehicle with brackets via
two heavy duty rod ends. A flexible heavy
duty shaft boot protects the push-pull rod
from the elements. Nylon stand-off washers
inside the boot keep the boot aligned with
the rod. The end caps, the outer cylinder,
and their corresponding threads have
withstood straight pull pressures of 16,000
Ibs. without parting. Quality long-lived
Parker seals are used throughout the cylinder.
The trim shaft rod is protected from the
elements by corrision treatment
SYSTEM AIR
DUMP VALVE
ma F
NITRILE
BLADDER
==.
PRESSURE
CHAMBER
HYDRAULIC
FLUID
RESERVOIR
SYSTEM AIR
DUMP VALVE
SYSTEM DESIGN continued....
POWER STEERING PRESSURE High Pressure
SENSING SAFETY SWITCH )
Tee Fitting to
fit as rquired
The power steering safety switch is
designed to withstand pressures in excess
of3,000 P.S.I.. These switches are provided
with multiple mounting fittings for the various
chassis’. Itis connected in-line with the high
side power steering hose. It automatically
shuts the Precision Steer Wheel Directional
Control System down in the event of power
steering failure.
Steering Gear
Pressure Switch
(normally open)
CONTROL PANEL
PRESSURE UP
— ==
PRESSURE DOWN SYSTEM PRESSURE GAUGE
MASTER ON-OFF SWITCH
WITH CIRCUIT BREAKER
PUSH TO TRIM BUTTON PANEL - VERTICAL
POSITION
Figure 11a: Power Center Steering Control Panel (as shown, Orientation may vary with:
-R= Right Hand Orientation: -V= Vertical Orientation; -L= Left Hand Orientation)
CONTROL PANEL.
The control panel houses the master/circuit breaker on-off switch, the trim momentary
switch, the miniature air regulator, and the air gauge. The control panel is designed for
various mounting methods; flush, stand-off, or bracket mounted. Optional is a PVC Side
Cover Mount.
SYSTEM DESIGN continued...
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MODEL N
ACCUMULATOR/COMPRESSOR PANEL
Designed and offered for those vehicles that require operating pressures above available
chassis air pressure. It consists of an accumulator, a compressor, fitted with an intake filter,
dryer/filter/moisture trap, Bosch relay, and an air pressure cut-off switch. All components
are pre-mounted and assembled on a galvanized panel for ease of installation.
VENT BOTTLE
The vent bottle is designed to allow con-
nection to the cylinder via two 1/4” lines.
This reservoir is essential in assuring that
only clean air is vented in and out of the
cylinder chambers as it operates. It also
will capture some fluid in the event of an
internal seal failure. The lid is sealed to
prevent any fluid being added.
OPERATION
The Howard POWER CENTER
STEERING System does what has never been
accomplished before in automotive history. It
power centers the steered wheels to a perfect,
driver selected position, for straight ahead driving
stability, which is not accomplished by any other
method.
The power source 1s air pressure
controlled by continuous duty 12 V.D.C. solenoid
valves, which charges an air-over hydraulic
accumulator. The accumulator transfers the air
pressure to hydraulic fluid via a nitril bladder. The
pressurized hydraulic fluid provides the force,
which holds the steering cylinder and steering
tires on a driver selected center. The vehicle’s
existing power steering system is many times
stronger than the power centering system.
Therefore, each system does what the other does
not do, and a most desirable working relationship
is established.
Whenever the vehicle’s steered wheels are
turned left or right by the power steering, the
power centering cylinder’s push or pull piston is
forced away from its center stop position . When
the steering wheel is released, the hydraulic
pressure acts as a springagainst the cylinder
piston, thus pushing the piston back against the
center stop block, thus re-centering the steering.
The fixed stop that the push-pull pistons
rest against gives the steering wheel an on-center
feel, which is also most desirable. This on-center
feel helps prevent drivers from oversteering the
vehicle, thus reducing unwanted rock and roll or
exaggerated tail swing.
As you know, driving down a road does not
always mean that the steering wheel will be
centered. Depending on road conditions and wind
conditions, holding off-center is sometimes
necessary and tiring in order to navigate a straight
line. This is where the trim cylinder, located
oposite the centering cylinder comes into play.
The trim piston is held in place by a liquid lock.
When the trim solenoid valve is opened, the
trim piston is free to travel to its driver selected
position. When the trim solenoid is closed,
the piston is again in a liquid lock state and cannot
move. This unique liquid lock system gives the
trim cylinder infinite adjustment and relieves the
driver of the unwanted strain of continually
holding against the wind or slanted road
condition*.
The control panel gives the driver
manual authority over use of the system and
allows the driver to adjust the sensitivity of the
steering wheel by regulating the amount of air
pressure going to the accumulator. The driver can
turn the system “on” or “off” as desired and, with
the use of the push button trim control, it is
possible to operate the trim cylinder while driving.
The “on-off” switch receives 12 V.D.C. power and
supplies power to the power steering safety
switch and the trim button. The power steering
safety switch supplies power to the air supply
valves and accumulator dump valves. The two
accumulator dump solenoid valves are normally
open, which leaves the bladder open to
atmosphere. They both close to trap the regulated
air pressure when they are engergized. The air
supply cut-off solenoid is normally closed
and opens when energized. The trim solenoid
valve 1s normally closed and only opens
when the trim button is pushed.
* NOTE!: To use the steering trim system, the pressure
must be set at 100 lbs. or above. The system trim works more
efficiently at higher pressure settings.
¡o
Sub Zero Winter Operation
NOTICE:
When operating in near or below zero temperatures, special MIL-H-5606 fluid
must be used. MIL-H-5606 fluid is available from RCP, PSWC Dealers, Pennzoil, Exxon,
Chevron, Mobil, Shell, Texaco, and others.
NOTE - in southern states, this low-temp fluid may not be readily available
from automobile service stations. It is widely used in aircraft and should be
available from those sources.
When using MIL-H-5606 fluid, the PSWC system will operate satisfactorily at
temperatures down to 40° below zero. This compares to a low limit of 10° above zero for
the standard power steering fluid that has been used in all earlier production units. Unless
winter operation in near zero temperatures is anticipated, power steering fluid works very
well and is more readily available.
Beginning in March 1997, all units produced will have MIL-H-5606 fluid suitable for
40° below zero operation. These units will be indentified by a decal on the accumulator
reservoir and the centering cylinder will have a “MW?” stamp in the end of the trim box.
SPECIAL NOTICE:
When operating in temperatures below 10° above zero, the fluid must be changed
to MIL-H-5606. Refer to Service Bulletin -05 for fluid change procedures.
Should winter operation be necessary with fluid other than MIL-H-5606 in
temperatures lower than 15° above zero, the system must be turned off well
before the 15° above zero temperature is reached. It must be left in the “off”
position until warmer temperatures prevail.
NOTE: Units producedprior to March 1997 were serviced
with standard power steering fluid. For owners that do not
anticipate winter travel in temperatures below 15° above zero,
there is no urgent need to change to the MIL-H-5606 fluid.
These units may continue to be serviced with power steering,
fluid.
14
5,000 Mile Maintenance Checks
1. Check the system’s Fluid Level.
| WARNING!:Never open fluid portion of the system when pressurized}
2. Check the Cylinder Mounting Brackets for looseness and safety retainer
cotter pins.
3. Check the Cylinders Protective Rubber Boot for tears or loose clamps.
4. Check the Hydraulic Lines and the Air Lines for chafing or abrasion.
5. Check the system's Wiring for chafing or abrasion.
6. Check the Vent Bottle for damage or fluid contamination. The Vent Bottle
should be clean and free of any fluids inside.
NOTE!: Fluid in Vent Bottle may indicate internal seal leakage.
7. Check the Power Steering Pressure Sensing Switch. With the System turned
“on” and the Regulator turned up to Maximum, turn the ignition switch to the
“on” position. The system’s Air Pressure Gauge should not read any
pressure at this point. Then start the vehicle’s engine. The Air Pressure
Gauge should now show air pressure building up.
WARNING!: Should the Air Pressure Gauge indicate Air
Pressure when ignition switch is only in the “on” position - without the
vehicle’s engine running - TURN THE SYSTEM “OFF”. DO NOT
use the system again until the Power Steering Pressure Sensing Switch
can be adjusted, repaired, or replaced.
WARNING!: When checking Cylinder Functions, keep
yourself clear of all Steering System Moving Parts. DO NOT put your
HANDS on the Cylinder when the Steering Wheel is being turned or
moved by someone else.
WARNING!: DO NOT loosen or remove any HYDRAULIC,
PNEUMATIC, or SOLENOID FITTINGS when the system is
energized. When working on this type of Pressurized system. WEAR
SAFETY GLASSES.
Js
Checking the System's Fluid Level
The Accumulator/Reservoir is equipped with a sight glass which indicates the
system's fluid level. When the fluid level reaches the add mark on the side of
the Accumulator, add the specified Hydraulic Fluid to bring the fluid level back
up to the top of the Fill Cap.
Only use fluid that meets specification MIL-H-5606 if sub zero winter
operation is anticipated or 1f the accumulator is marked with a decal indicating
low temperature fluid. If accumulator is not marked with the low temp fluid decal
and no zub zero winter driving is anticipated then standard power steering fluid
may be used. Only check fluid level when the cylinder is centered!
WARNING!: NEVER OPEN the Fill Cap when the System is Pressurized.
Care must always be taken to keep dirt or debris from entering the Accumulator Before
removing the Fill Cap, clean all dirt, grease, or debris from the Fill Cap area.
Due to its design, the Accumulator/Reservoir cannot be overfilled. However, the
Accumulator/Resrvoir can appear to be full of fluid if the steered wheels are not in the
straight ahead position. Therefore, checking the fluid level should be performed according
to the following procedure:
Start the Vehicle’s engine.
Turn the PSWC System “on” and adjust pressure over 100 P.S.I..
With your hands off the the steering wheel, move the vehicle forward or backward to
allow the PSWC System to center itself.
Turn both the Engine and the System “off”. The correct fluid level will now be indicated
in the system’s sight glass.
Replenish the system fluid* to maintain the level at the top of the Fill Cap Threads.
* See Note Box above or refer to page 14 of this manual for proper fluid callout.
NOTE!: If the correct sequence for checking oil is not followed, the system
can appear to be overfilled. This means that the Centering Cylinder was not
centered properly and fluid will escape the Accumulator/Reservoir when the
Fill Cap is removed. Should this occur, repeat procedures 1-5 and then re-
check fluid level.
16
TROUBLESHOOTING - TECHNICAL
PRELIMINARY CHECKS
It goes without saying, that the best
diagnostic tool you have available to you is
the degree of knowledge you acquire about
new products as they enter your chosen
professional atmosphere. Do not create
problems that do not exist - the PSWC
System 1s new technology - but 1s not
mysterious - only new. It’s design is straight
forward - pneumatics and hydraulics
controlled by 12 V.D.C. switches and
solenoid valves.
Preliminary Test: Set the parking
brake on the vehicle. Jack the front axle up,
raising the front tires off the ground. Place
the appropriate jack stands under the front
axle, being sure they will not interfere with
any steering components movement. Start
the vehicle engine and turn the power system
on. Turn the air regulator knob fully
clockwise till it stops. The air pressure gauge
should be reading above 100 P.S.I.. The
power center system should return and hold
the steering wheel and front tires straight
ahead. Turn the steering wheel 1/2 turn to
the left and release. The wheel should return
to center hands off. Repeat 1/2 turn to the
right. The wheel should return to center. Test
the trim function. Turn the steering wheel 1/
2 turn to the left and press the trim button
for 15 seconds. Release the trim button and
the steering wheel. The steering wheel should
be off-center approximately 1/3 turn to the
left. Turn the wheel one full turn to the right
and hold the trim button down for 15
seconds again. Release the button and the
steering wheel. The steering wheel should
be off-center approximately 1/3 turn to the
right.
Equi Distant
9-10 o'clock 7 Г
position
12 o'clock position >
After Trimming to Left
Wheel stays Left
Steering wheel at
Straight Ahead
Equi Distant 3 odos
| / position
After Trimming to Right
Wheel stays Right
If the PSWC System functions as
described each direction but not equally in
each direction or only in one direction, go to
“Setting the Trim (Centering)”.
If it does not function as described,
proceed to the troubleshooting guide and
search for the symptom you are experiencing.
The troubleshooting guide that follows
is divided into three columns: Symptoms,
Causes, and a Check List. The guide will
refer you to the appropriate schematic as
needed.
NOTE!:
items. Do
without fir
approval.
The internal parts of the cylinder and tri
not replace it out of your soci
st contacting our customer ser
This quick phone call can easi
incurring ynnecessary expenses.
vice department for
ly prevent anyone from
box are not field service
or order a replacement
TROUBLESHOOTING GI
(Syste
SYMPTOM
Air Compressor does not
come on / No air pressure
registers on guage
NOTE!: The easiest
way to check voltage at the
solenoids 1s to disconnect
the wires coming off the
solenoids that go to
chassis ground. Place
your test light or test meter
between each wire and
chassis ground. This
procedure will also
eliminate the possibility of
a corroded or faulty
ground connection. Loss
of voltage to any of the
components (a-e) will
disable the system.
CAUSE
Loss of electrical power.
Vehicle engine must be
running and power steering
pressure must be adequate to
trigger the power steering
safety switch. This switch
provides voltage to all other
electrical components.
CAUTION!: Before you
unscrew the trim solenoid
from the trim box, care
must be taken to clean all
dirt, grease. or debris
from around the base of
the valve. Malfunction of
the cylinder due to
contamination does not
constitute a faulty
component.
18
Loss of continuity (open
circuit) from compressor
pressure switch to ground
(switch 1s normally “closed”
and “opens” when system
reaches cut off pressure)
Faulty compressor switch
UIDE
m using Kit Furnished Air Compressor)
CHECKLIST
Start engine. Turn pressure
regulator fully clockwise to
stop. If air pressure does not
come up- then proceed.
Follow “System with kit
supplied air compressor
Electric schematic”.
Check voltage at:
a. 20 amp. circuit breaker
constant 12V power
supply
b. bosch relay on compressor
panel
1) 12ga. red wire
(constant12V рут.
supply)
2) 14ga. orange wire -( power
steering s pressure sensing
switch)
Check ground wire from:
a. compressor switch to
panel (chassis ground)
b. continuity across
compressor switch
lead wires
Replace compressor pressure
switch.
SYMPTOM
CAUSE
Air compressor “cycles” on Air leak (s) in system
or won 't shut off
The system returns the wheel
from a left and right hand
turn, but will not trim right
or left.
System pulls to the left or
right when turned “on” and
trim won't respond
NOTE!: Do notuse a
knife or sharp
instrument to slice the
tubing over the barbs.
Nicking the barbs will
result in an air leak
when the hose is
reattached.Use a small
flame or heat gun to
soften tubing, then pull
it off. Trim damaged
tubing and reinstall
Supply side is 1/4” black
& regulated pressure side
1/4” blue line
1. Loss of voltage or chassis
ground to the trim solenoid
valve.
2. System “off-center” or
“out of trim range”
see- “Setting the trim-
Centering”- page 20-21
CAUTION!: Before
you unscrew the trim
solenoid from the trim
box, care must be taken
to clean all dirt, grease.
or debris from around
the base of the valve.
Malfunction of the
cylinder due to
contamination does not
constitute a faulty
component.
CHECKLIST
See system air & hydraulic
schematic- perform soapy
water test for air bubbles.
a. After compressor is
running- adjust air pressure
regulator counter-clockwise
to stop (adjust to “zero”psi)
b. 1f compressor shuts off
check blue line for leak
c. trace black line if
. compressor continues to run.
1. Start engine and turn
system on. Follow the
System Electrical
Schematic.
a. Disconnect the ground
lead of the trim solenoid.
Depress the trim button
and test voltage from this
wire to ground. You should
read approximately
12VDC. If you do not,
check connections to the
trim button and the wire
leading to the solenoid. If
you have voltage to the
solenoid, but do not have
voltage from the solenoid
ground lead to chassis
ground, turn the system
and engine “off”.
See Caution and proceed. Clip
the leads, grabbing the
knurled brass base,
unscrew it like a light bulb
and screw the new valve
in firmly by hand. Do not
use any tools to tighten the
solenoid valve.Reconnect
the wires. Repeat
Preliminary Test
on page 17.
=.
—
Setting the Trim (Centering)
STEP 1: Start engine, turn Precision Steer Wheel Directional Control System “on”
(this centers the steering position).
STEP 2: CENTERING TRIM END: Turn the steering wheel to the direction that moves
the WRENCH FLAT on the TRIM SHAFT out from under the ALIGNMENT MARKER.
With the wheels turned, PRESS THE TRIM BUTTON to position the edge of the wrench
flat at the edge of the MARKER RING. (Figure 20a)
Figure 20a: [xiv END OF CYLINDER PL AS T I C
IS CENTERED WHEN ALIGNMENT oe
EDGE OF PLASTIC SLEEVE ik
SLEEVE IS ALIGNED WITH
EDGE OF WRENCH FLAT
WITH PLASTIC SLEEVE
PUSHED AGAINST END OF
CYLINDER ——
HERE =>
| e
Raita
WRENCH FLAT
STEP 3: CENTERING THE CYLINDER: Loosen the four (4) CLAMP BOLTS so that
TIE ROD BRACKET can slip as the cylinder finds center. Straighten the front wheels as
discussed in step 4. When the wheels are centered, securely tighten the four (4) bolts
(Torque to 30-35 Ft/Lb). (Figure 20b) NOTE: A U-Bolt type Clamp Bracket may be
used.
Figure 20b:
CAST TIE ROD
CLAMP WITH
BOLTS
U-BOLT TYPE
TIE ROD
CLAMP
STEP 4: CENTERING THE WHEELS: This is done by sighting along the OUTSIDE
of the Front Tires looking towards the Rear Tires. (Figure 20c) Turn the steering wheel
as required to even the Line-of-Sight Interception at the Rear Tires. A creeper may be
useful.
Figure 20c:
= 4 RE CS SAAL Ca
( ) I] 1e J) = Gi | me =
f — | E
É | É EJ =
=
= +
| Always double check the vehicle to MAKE SURE that the TRIM is CENTERED
PROPERLY. NEVER ASSUME!!!
20
SYMPTOM
CAUSE
Air compressor “cycles” on Air leak (s) in system
or won 't shut off
The system returns the wheel
from a left and right hand
turn, but will not trim right
or left.
System pulls to the left or
right when turned “on” and
trim won't respond
NOTE!: Do notuse a
knife or sharp
instrument to slice the
tubing over the barbs.
Nicking the barbs will
result in an air leak
when the hose is
reattached.Use a small
flame or heat gun to
soften tubing, then pull
it off. Trim damaged
tubing and reinstall
Supply side is 1/4” black
& regulated pressure side
1/4” blue line
1. Loss of voltage or chassis
ground to the trim solenoid
valve.
2. System “off-center” or
“out of trim range”
see- “Setting the trim-
Centering”- page 20-21
CAUTION!: Before
you unscrew the trim
solenoid from the trim
box, care must be taken
to clean all dirt, grease.
or debris from around
the base of the valve.
Malfunction of the
cylinder due to
contamination does not
constitute a faulty
component.
CHECKLIST
See system air & hydraulic
schematic- perform soapy
water test for air bubbles.
a. After compressor is
running- adjust air pressure
regulator counter-clockwise
to stop (adjust to “zero”psi)
b. 1f compressor shuts off
check blue line for leak
c. trace black line if
. compressor continues to run.
1. Start engine and turn
system on. Follow the
System Electrical
Schematic.
a. Disconnect the ground
lead of the trim solenoid.
Depress the trim button
and test voltage from this
wire to ground. You should
read approximately
12VDC. If you do not,
check connections to the
trim button and the wire
leading to the solenoid. If
you have voltage to the
solenoid, but do not have
voltage from the solenoid
ground lead to chassis
ground, turn the system
and engine “off”.
See Caution and proceed. Clip
the leads, grabbing the
knurled brass base,
unscrew it like a light bulb
and screw the new valve
in firmly by hand. Do not
use any tools to tighten the
solenoid valve.Reconnect
the wires. Repeat
Preliminary Test
on page 17.
Setting the Trim - Adjustable Slider Plate Mount
Centering the Cylinder (Adjustable Slide Mount with Clamp Angles)
(Complete Steps 1,2 and 4 on previous page before proceeding with the folowing.)
Loosen the four (4) CLAMP BOLTS so that the Adjustable Slider clamp can slip on
the base plate as the cylinder is allowed to find center. Straighten the front steer wheels
as discussed in (Centering the Wheels) on page 21. When the wheels are straight ahead,
securely tighten the four (4) 1/2 flanged clamp bolts. Torque to approximately 85 ft/lb..
CENTERING
CYLINDER
FRAME MOUNT BRACKET so A
CLAMP BOLTS (4 EA) se ul
SLIDE PLATE ADJUSTMENT - LOOSEN
CLAMP BOLTS AND ALLOW PLATE TO
MOVE TO CENTER CYLINDER
Other Driving Situations:
Sympton: Vehicle wanders and won't track straight (when trimmed for
straight) as expected.
Cause: Toe-In not set to specs.
° Check Toe. Total Toe for all chassis needs to be set at 1/8” positive.
(Toed in)
o Check to make sure tie rod ends are twisted (see page 23) to take
out any rotational slop. This includes tie rods on straight axles and
drag links on independent front suspensions.
° Check to make sure joints are well lubricated.
: Check mounting bracket for loose bolts and or clamps.
° Check cylinder rod ends for “looseness”.
, Check chassis for worn or loose bushing (i.e. track bars, stabilizer
bars..).
Prior to chassis alignment, mark position of system tie rod or drag link
clamp bracket for proper trim operation after alignment.
Call 1-800-879-4277 for additional assistance.
e-mail: [email protected]
Drivability Symtoms:
Vehicle Eccessive Wandering:
Check Toe In. Toe needs to be set at 1/8” positive.
With Power Center Steering the recommended Toe-In Setting is 1/8”.
Its been proven with thousands of power centering systems in service for
millions of accumulated miles driven with the 1/8” Toe-In setting, tire wear
is not affected.
A major tire company conducted a study on trucks and buses with and
without Power Center Steering. The tire company reported a 55%
improvement in Steer Wheel Tire Life on vehicles with Power Center Steering
because of the non-cupping smooth tire wear pattern.
The illustration below shows the almost unmeasurable difference in
Tire Foot Print between 1/16” and 1/8” toe settings which explains why no
difference in tire wear could be expexted because of increased toe.
F FRONT DISTANCE IN 1/32" ——
1 1 /64 H / N 1 /6 4 Li | N E dim =
A | N / \
1-1/2 THOUSANDTHS
OF AN INCH EQUALS 1/2 THE
THICKNESS OF THIS PAPER)
1-12 THOUSANDTHS | | 7/77 77
OF AN INCH A
1/64" OUT Z > 1/64” OUT
-— REAR DISTANCE OUT 1/32" -
DIFFERENCE FROM 1/16" TO 1/8" TOE-IN
22
Trim doesn’t seem to hold properly:
Check for eccessive Tie Rod Rotation
Minimizing Excess Tie Rod Motion
On SOLID FRONT AxleT!lE
Vehicles, the Tie Rod System КОР) = TROL FROM ROD
— г END SLACK
will rock Front-and-Back when
the Steered Wheels are turned
left and right with the Power
Center Steering System engaged.
To Minimize this motion:
a) Loosen a Tie Rod End Clamp,
b) Offset the Tie Rod Ends in
opposite directions (Figure 23a)” TIE ~~ ROD
- backing off only slightly after C LA MT
; ; BRACKET
rotational movement in each
direction stops, and с)
Retighten the Tie Rod Clamp.
This proceedure is highly
recommended for all TIE ROD
MOUNTED systems also
including mounting on the Drag
Link.
TWIST ROD ENDS OPPOSITE
DIRECTIONS TO TAKE OUT
Figure 23a: ROLL SLACK
Tools Required for Installing
Howard Precision SteerWheel Directional control System
The following general list identifies tools commonly used in each PSWDC
installation:
* 1/2” Impact Wrench* (to break nuts loose)
e 1-1/8” Deep Impact Socket
» Torque Wrench (if available, this is preferred method to retorque the
nuts to factory specs)
* 3/8” thru 1-1/8” Combination Wrench Set
« SCREW GUN with Phillips & Standard Heads, 1/4” Socket,
5/16” Socket, and 3/8” Socket
° Phillips Screwdriver
* Standard Screwdriver
Tape Measure
* 3/8” Cordless Drill, Electric Drill, or Air Drill
Medium Ball Peen Hammer
* Wire Cutters, Crimpers, & Stripping Tools
* 12-volt “hot wire” Test Light
* Razor Knife or Plastic Tubing Cutter
24
+ Hydraulic Fluid that meets the specification MIL-H-5606 as
manufactured by:
Pennzoil, Exxon, Chevron, Mobil, Shell, Texaco, etc..
* Air Brake Hose Fittings, Air Brake Tubing, and General Purpose
Electrical Wiring used for servicing the PSWDC System must meet
D.O.T. Specifications for the application.
SAE Guidlines for Maximum Allowable Torque
for Fine Thread Series Bolts
* When installing Bolts, it is good
practice to use torque wrenches (when
available) to determine when bolts have
been adequately tightened.
CAUTION!: Impact wrenches can
over or under torque the bolt, thus
resulting in a failure to the bolt by over
torquing or the slipping or failure of
component brackets by undertorquing.
* The Torquing chart in the next column
shows the Maximum Allowable Torque
on Bolts - Fine Thread Series.
* Consult the original equipment manual
on recommended torques.
Maximum Allowable Torque
Fine Thread Series
Dia. Size Max.
and Torque
Threads/Inch | Grade Ft.- Lbs.
3/8 - 24 NF 5 35
8 45
7/16 - 20 NF 5 55
8 70
1/2 - 20 NF 5 92
8 129
9/16 - 18 NF 5 131
8 185
5/8 - 18 NF 5 181
8 256
3/4 -16 NF 5 316
8 446
7/8 - 14 NF 5 502
8 710
1-14 NF 5 748
8 1,057
1-1/8 - 12 NF 5 949
8 1,522
1-1/4 - 12 NF 5 1.313
8 2,107
26
Additonal Vehicle Steering System
Maintenance Tips
Prevent internal “bottoming” of the steering gear. Carefully check Steering
Stops to be sure that they meet the manufacturer’s specifications.
Regularly check the PSWDC System’s Fluid Level in the accumulator sight
glass as well as the Fluid Level in the Power Steering System Reservoir.
Keep the tires inflated to the correct pressure.
Investigate and immediately correct the cause of play, rattle, or shimmy in
any part of the steering linkage or steering mechanism.
Remove the cause of Steering Column Misalignment.
After any vehicle accident, inspect for any damaged PSWDC System
Components or Power Steering Component damage.
Do not attempt to weld any broken steering component. Replace the component
with original Equipment Replacement Parts only.
Do not straighten any bent steering component - not by cold bending or by
heating the component for bending.
Always clean dirt and debris off of the PSWDC System Fill Cap Area before
removing the Fill Cap. Prevent dirt or debris contamination of your PSWDC
System.
Investigate and correct any found external leaks, no matter how minor.
Replace filters and pumps in compliance with specifications.
Have the vehicles’ alignment checked annually, front and rear, by a qualified
shop.
King Pins/Ball Joint Lubrication should be done with tires off the ground.
Check the Cylinder Mounting Brackets for both looseness and that the
Safety Retainer Cotter Pins have been installed.
Additional Steering Tips
* (Check the Hydraulic Lines and the Air Lines for Chaffing and Abrasions.
Also check Line Connections for loosenes.
* Check the systems Wiring for Chaffing and Abrasiouns.
* Check the overall condition of the Vent Reservoir Bottle. The bottle should
be clean andfree of any excessive moisture .
NOTE!: Never Add Fluid to the Vent Reservoir Bottle!
* Check the Power Steering Pressure Sensing Switch. With the System turned
“on” and the Regulator set to mid-range, turn the ignition switch to the “on”
position. Do not start the engine. The system’s Air Pressure Gauge should
not read (indicate) any pressure at this point. Start the vehicle’s engine.
The PCS System will now turn “on” (activate).
WARNING!: Should the Air Pressure Gauge indicate Air Pressure when the
Ignition Switch in the “on” position - without the vehicle s engine running
- TURN THE SYSTEM “OFF”. DO NOT use the system again until the
Power Steering Pressure Sensing Switch can be replaced.
WARNING!: When checking Cylinder Functions, keep hands and arms clear
of all Steering Sytem Moving Parts. DO NOT put your HANDS on the Cylinder
when the Steering Wheel is being turned or moved by someone else.
WARNING!: DO NOT loosen or remove any HYDRAULIC FITTINGS,
PNEUMATIC FITTINGS, or SOLENOID FITTINGS when the system is
energized. When working on any type of Pressurized System
- WEAR SAFETY GLASSES!
— 1.
Final Inspection
ACCUMULATOR: Start engine.Turn PCS System “on” and straighten the steered
wheels. Turn Engine “off”. Check the Accumulator Sight Glass. No air Gap should
be visible. Top-Off as required. Check for leaks (AIR or FLUID). NOTE: Check
fluid level in Power Steering Reservoir... Replenish if required.
CYLINDER: Check mounting bolts and pins for looseness or missing cotter pins.
Check routing of harnesses for interference with suspension moving parts. Check
for leaks (FLUID and AIR). Turn wheels left and right, Lock to Lock, to Check
Cylinder clearances. Make sure that the steering stops on the spindle are contact-
ing the axle before the cylinder bottoms out internally.
Also double check that the TIE ROD CLAMP does not interfere with the TIE ROD
TUBE travel (i.e.: shock mounts, sway bars, etc.).
NOTE: If the Tie Rod Tube contacts the centering cylinder in a full left-hand turn
or right-hand re-adjust the clamp bracket if possible. RE-CHECK for contact. If
there is still interference then call Customer Service.
CONTROL: Turn the PCS “off”. -Air Gauge should bleed to O PS.I.. Turn system
back “on” - rotate regulator clockwise to stop. Maximum pressure is about 170
PS.I.. Turn the regulator counterclockwise to stop. System Air Pressure Gauge
should bleed to 0 PS.I.. Reset sytem to 100 PS.I.
POWER STEERING PRESSURE SENSING SWITCH: Check for leaks (FLUID).
Turn Engine “off”. System Air Pressure should bleed to O PS.I.. Turn ignition to
“on” position - System Air Pressure should remain at O PS.I.. Start engine, system
Air Pressure should return to previous setting.
AIR SUPPLY SOLENOID (Installed in kits without compressors): If Sytem Air
Pressure registers when system is turned on - solenoid is OK.
TRIM BUTTON: With the wheels straight ahead, turn the steering wheel one (1)
revolution to the LEFT, push and hold TRIM BUTTON while another person watches
the TRIM END of the Cylinder - Cylinder should move toward tie rod end. Turn
steering Wheel two (2) revolutions to the RIGHT and repeat the TRIM TEST. This
time the Cylinder should move away from the tie rod end. Re-center Trim Piston.
NOTE: Cylinder movement “toward” and “away from” Tie Rod End might be
reversed from above depending upon final installation orientation of the cylinder.
28
Lubricate all Front-end components.

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