A Breakthrough In Precision Steer Wheel Control Technology Does Away With The Costly Heavy Vehicle Operational Problems Caused By the Steering Geometry Design Of The Last Century. The New Technology Advances The State Of The Art In Drivability To A Level Of Perfection Entirely New To The Heavy Vehicle Industry Greatly Reducing Driving Fatigue and Related Highway Safety Problems.

Fundamentally what has been overlooked for so many years is the lack of heavy vehicle directional stability that is caused by the directionally unstable behavior of the steer wheels that the steering geometry still does not control or prevent.

This drivability trouble maker has now been solved by the development of Precision Steer Wheel Directional Control Technology. This document has been carefully edited for accurate verifiable information on solving this industry-wide heavy vehicle design oversight. The Precision Steer Wheel Control System is presently in service on thousands of heavy over-the-road buses, trucks and recreational vehicles that have collectively been driven more than a hundred and fifty million in-service miles.

The service test established that beyond question regardless of make or model, all of the randomly selected heavy vehicles in the test had the same inherent lack of directional stability until they were equipped with the Precision Steer Wheel Control System. During the millions of in-service miles, the drivers universally reported a dramatic reduction in driving fatigue and praised the overall improvement in drivability and steer wheel tire blowout controllability that is also achieved by the precision steer wheel control system.

The verifiable information in this document has been written to be more easily understood by the largest number of readers.

STEERING AXLE INSTALLATION

This document can be found at www.hpcss.com

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The development of Precision Steer Wheel Control Technology advances the state of the art in heavy vehicle directional stability to a level of perfection that is completely new to the heavy vehicle industry, resulting in a vast improvement in drivability and a considerable reduction in driving fatigue. Considering the amazing number of operational and drivability safety problems solved by the new technology, it is beyond question the most important next step to be taken for improving heavy vehicle highway safety.

· Precision Steer Wheel Control completely solves the puzzling long-standing premature steer wheel tire wear problem that was caused by the unstable behavior of the steer wheels. Therefore, the savings in steer wheel tire expense will pay for the new technology many times over during the normal service life of a heavy vehicle ( see page 9).

· Precision Steer Wheel Control achieves an amazing level of steer wheel tire blowout controllability, verified by over twenty documented steer wheel blowouts where drivers report easy vehicle controllability, without the customary directional steering control problem (see page 9).

· Precision Steer Wheel Control does away with the excessive driver steering input required to control the unstable behavior of the steer wheels that conventional steering geometry does not control, thereby making a major reduction in driving fatigue.

· Precision Steer Wheel Control makes a considerable improvement in crosswind drivability, by preventing the steer wheels from caster steering downwind in response to the wind gusts, thereby making a major reduction in crosswind driving fatigue (see page 7).

· Precision Steer Wheel Control completely eliminates road wander that is caused by the unstable behavior of the steer wheels that conventional steering geometry does not control or prevent.

· Precision Steer Wheel Control does away with steering wheel pull on crowned or slanted roads that is caused by steer wheel caster steering to the low side of the road (see page 7).

· Precision Steer Wheel Control greatly reduces the potential for excessive driver oversteer during a highway emergency, thereby greatly reducing the potential for Heavy Vehicle Catastrophic Roll Over Accidents.

· Precision Steer Wheel Control makes team driving safer for two important reasons. The driving is easier and less fatiguing, and drivers report they are able to get more rest and sleep because of the non-swaying directionally stable ride.

· With Precision Steer Wheel Control trucks pulling multiple trailers are not only safer and much less fatiguing to drive, they are also much easier to share the highways with because the trailers stay in line with the directionally stable truck.

· More Effective Driver Training: Driver training instructors report that student drivers easily become proficient in keeping a directionally stable heavy vehicle safely under control and are not as inclined to oversteer, therefore, they are more able to concentrate on learning other important highway safety issues without the distraction of having to concentrate on keeping a directionally unstable vehicle under control.

· Driver Retention: It can be reasoned that dramatically reducing driving fatigue with Precision Steer Wheel Control will improve driver attitude about their profession and will likely be an important factor in reducing the number of heavy vehicle drivers who decide life on the highway is not for them. It can also be an enticement for a number of disillusioned drivers to return to the profession where something far more important than providing a comfortable seat has been done to make the highway a more satisfying place to be. Only time will tell how much this will help to increase the available driver pool. However, judging by the enthusiastic response from the drivers who are presently driving with Precision Steer Wheel Directional Control System, it's a safe bet that the improvement will be significant.

· The Driver Fatigue Studies that have been conducted with trucks equipped with Precision Steer Wheel Control verify a major reduction in Driving Fatigue and may very well have a favorable influence in the Hours Of Service Rules in the future.

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A Word of Caution

The accuracy of the claims in this document are easily verified. Even so there will be skeptics who will be reluctant to accept what they believed was true about conventional steering geometry has now been proven to be wrong.

The Howard Precision Steer Wheel Control System™

is made under U.S. Patent Number 5,536,028. Other Patents granted and pending.

The Critical Need For Heavy Vehicle Directional Stability - The Longest Running Design Oversight

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Considering the many outstanding technical accomplishments made by the heavy vehicle industry, in advancing the state of the art in function and reliability of heavy over-the-road buses and trucks, it is not easy to understand how the very capable heavy vehicle design community could have, for going on a hundred years, failed to recognize the unstable behavior of the steer wheels inherent to state of the art steering geometry, that is responsible for the lack of heavy vehicle directional stability and related highway safety problems.

It can be reasoned that in the beginning of the growing heavy vehicle industry, the need to develop technology to solve the many function and reliability problems that were of a major concern to the consumers, was given priority

over the development of technology to solve heavy vehicle drivability problems that was accepted as normal by the heavy vehicle operators. Therefore, empirical knowledge prevailed, giving credit to the mistaken idea that acceptable drivability could be achieved by the simple low-cost geometry of the steer wheels. There is little doubt that the unproven conventional wisdom influenced the design used throughout the industry by designers who endeavored to achieve acceptable drivability with steering geometry, leaving the lack of directional stability that could not be achieved with the steering geometry to be dealt with by corrective steering input from the vehicle driver. Therefore, driving heavy vehicles lacking in directional stability became accepted as normal in the heavy vehicle industry.

The Pervasive Spread Of Misleading Conventional Wisdom

A good example is the misleading information found in text books claiming the supposed benefits of steer wheel castering, that is to some degree responsible for the long-term industry-wide failure to develop more suitable technology. For example, a current best selling SAE Motor Truck Engineering Hand Book that was first published in 1910 and the current fourth edition of this book published in 1994, repeats the mistaken assumptions that are also

repeated in many other publications with reference to the effect of steer wheel castering. In this SAE book, Chapter XII, page 317 on Steering Geometry, there are two grossly misleading references made which are, "caster maintains a vehicle on an even straightaway course without much steering effort," and the second being, "caster aids materially in ease of steering because the wheel has a natural tendency to align itself."

The Function of a Castered Wheel

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It will come as a surprise to many well informed individuals that steer wheel castering does not "maintain a vehicle on an even straightaway course," as the book states. The unstable behavior of the steer wheels inherent to conventional steering geometry actually allows heavy over-the-road vehicles to be seriously lacking in directional stability that requires an inordinate amount of repetitive driver steering corrections to maintain directional control of the vehicle, greatly adding to driver fatigue.

The second claim that a castered wheel has a natural tendency to align itself and that it aids materially in the ease of steering, is taken out of context and is also not true. A good example of castering is to observe how the castered wheels on a desk chair

are guided in the direction that lateral force is being applied. Rather than making the chair go straight, it allows the chair to be freely moved in the direction of lateral force.

The Definition of a Castered Wheel denotes a wheel that is mechanically arranged so that it trails behind a forward pivot and is guided by the lateral movement of the forward pivot. The castered wheel has a natural tendency to follow the lateral movement of the pivot. This explains why the castered wheels of a heavy vehicle turn downwind in the direction of the lateral movement of the vehicle in response to the wind gust, and must be directionally controlled by corrective steering input from the vehicle driver.

Steer Wheel Caster Is A By-Product Of Achieving Steering Wheel Returnability

Heavy vehicle steer wheel castering is a by-product of slanting the king pin aft at the top end to achieve steering wheel returnability. The steer wheel that turns to the aft side of the slanted king pin lifts the weight of the vehicle creating a turning lift effect. When the vehicle driver releases the steering wheel after turning, the weight of the vehicle returns the steer wheel toward the lower most straight ahead position, where the steer wheel returnability effect becomes inactive. The king pin angle is referred to as the caster angle, giving rise to the mistaken assumption that castering the steer wheels achieves the steering wheel returnability that is actually the result of

the turning lift effect. Two highly important considerations that should be considered are: The steering wheel returnability achieved by the turning-lift effect diminishes as the steer wheels approach the on-center straight-ahead position, and therefore has very little effect on the unstable behavior of the steer wheels when going straight. The second and most important design consideration in achieving heavy vehicle directional stability is, the steer wheels must be controlled in the on-center position with a degree of perfection that cannot be achieved by state of the art steering geometry and related steering components.

The Steer Wheel Turning Lift Effect

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In the beginning when the horseless carriage first took to the road, uncomplicated simple technology was of great importance. As a product improvement, the steering tiller was traded for a steering wheel that initially presented a problem. The steering wheel would stay turned after turning a corner. The lack of steering wheel returnability was solved by the simple method of slanting the steer wheel king pins aft at the top end to accomplish a turning-lift effect created by the steer wheel that turns to the aft side of the slanted king pin , thereby lifting the vehicle by a small amount (page 6, figure E). When the vehicle driver releases the steering wheel after turning, the weight of the vehicle causes the steer wheel that lifted the vehicle to return toward the on-center driving position (figure F). Because the steer wheels are connected by a tie rod, both wheels are made to return to the on-center driving position. To better understand the turning-lift effect, a graphic example that most everyone is familiar with is the post of a farm

gate that becomes slanted due to the weight of the gate in the closed position (figure A). When the gate is opened 90 degrees in either direction, the low end of the gate is lifted by turning to a non-slanting side of the post (figures B and C), creating a turning-lift effect. When the gate is released, the weight of the gate will cause it to swing back to the lower most closed position of the slanted post, where the turning-lift effect diminishes and becomes almost neutral and is not able to hold the gate in the closed position, requiring a suitable method to keep it closed. In a similar manner to the turning-lift of the farm gate, when the steer wheels of a vehicle return toward the on-center driving position, the turning-lift effect also diminishes and does not have enough centering force to keep the steer wheels tracking straight in the on-center driving position. Therefore, the unstable behavior of the steer wheels near the on-center position must be controlled by repetitive driver steering corrections.

The WIDELY MISUNDERSTOOD Adverse Effects of Steer Wheel Castering

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The inherent lack of steer wheel directional stability in the on-center driving position is made worse because the identical slanted king pin angle, that produces the turning-lift effect, also produces a steer wheel castering effect (figure F) that greatly adds to the unstable behavior of the steer wheels during crosswind and crowned road driving conditions. It is amazing that over the many years because of an unintentional misleading choice of terms, the adverse effect of steer wheel castering has failed to be better understood. It can be reasoned that in the beginning, because the turning lift and caster angles are one and the same, the shorter term caster angle was probably chosen over a more complex term such as turning-lift angle. For as long as anyone can remember, the standard reference for the required king pin turning lift angle in vehicle specification manuals has always been referred to in degrees of caster angle. Therefore, it is not surprising that it

has been mistakenly assumed throughout the many years that steer wheel castering in some manner must have been beneficial to heavy vehicle directional stability, when in fact the opposite is true. Over the many years, the majority of the text books and engineering papers that have been written about heavy vehicle steering geometry, have copied and repeated the mistaken assumption that castering the steer wheels makes a contribution to the directional stability of heavy over-the-road vehicles. Unfounded theories attempting to explain how the castered wheel functions to make a vehicle directionally stable, have been repeated in various technical publications, greatly adding to the confusion. It is amazing how someone whose desk chair has castered wheels that allows the chair to freely move in any direction (figure D), could believe in some manner, when applied to a highway vehicle, that castering keeps the steer wheels tracking straight.

LATERAL VEHICLE MOVEMENT GUIDES THE CASTERED WHEELS

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Vehicle in Tow

A convincing example of how the lateral movement of a vehicle guides the castered wheels, is to observe the behavior of the steer wheels of a vehicle that is being towed by another vehicle, using a conventional hookup, whereby the vehicle in tow follows the precise lateral movements of the tow vehicle. As the tow vehicle turns, the castered wheels of the vehicle in tow obediently turn in the direction of the lateral movement with out resisting the deviation from straight line steering as the text book mistakenly claims. (See Figure G)

Tow Vehicle

FigureG

Another example of the castered wheel following the lateral movement of a vehicle, is steering wheel pull on a crowned or slanted road, in response to the tendency of a heavy vehicle to move laterally to the low side of the road.

STEER WHEEL CASTERING: THE PRIMARY CAUSE OF CROSSWIND DRIVING FATIGUE

When driving in a crosswind, the castered wheels are guided downwind by the lateral vehicle movement caused by the wind force acting on the side of the vehicle, requiring a corresponding amount of corrective driver steering input to keep the vehicle under control. Professional heavy vehicle drivers universally agree that crosswind driving is one of the most dreaded driving conditions they frequently must endure. During crosswind driving with The New Precision Steer Wheel Directional Control Technology, the steer wheels are prevented from castering downwind, and made to track exceptionally straight thereby greatly reducing the number of driver steering corrections required to keep the

vehicle under control, resulting in a major reduction in crosswind driving fatigue. Crowned and imperfect road surfaces also cause undesirable steering feedback from the castered wheels that must be counteracted by corrective steering input from the vehicle driver to prevent the vehicle from leaving the road. During adverse driving conditions with The Precision Steer Wheel Directional Control System the steer wheels are made to track exceptionally straight thereby making a considerable reduction in the driver steering input required to keep the vehicle safely tracking straight and under control, reducing driving fatigue and greatly improving highway safety.

ACHIEVING HEAVY VEHICLE DIRECTIONAL STABILITY

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To be directionally stable, a vehicle must be designed so that the steer wheels track exceptionally straight without requiring driver steering corrections to keep the vehicle going straight, thereby greatly reducing the driver work-load. The industry-wide method of slanting the king pins of the steer wheels to achieve steering wheel returnability, also achieves steer wheel castering that greatly adds to the unstable behavior of the steer wheels, resulting in a surprising number of drivability and operational problems (see pages 5 and 6).

While the low-cost simple method of achieving steering wheel returnability is desirable from a manufacturing point of view, the resultant operational problems are very undesirable to the consumers, especially to the heavy vehicle drivers who must endure the million upon millions of miles that are many times more fatiguing to drive than they would be in a directionally stable vehicles. Historians will find it hard to rationalize, how the hundred-year-old method of achieving steering wheel returnability by the turning-lift effect could have been used for so long, without steer wheel castering problems being recognized for the negative effect on heavy vehicle drivability. It was not for the lack of consumer complaints however, about the repetitive steering corrections required to maintain directional

control, road wander, steering wheel pull, crosswind driving fatigue, and the costly steer wheel accelerated tire wear problem.

The possibility of solving so many of the long-standing operational problems that would have been paid for by savings in steer wheel tire expense, must have never been realized by the industry in general. Considering that the simple method of achieving steering wheel returnability with all of the adverse side effects has been accepted for going on a hundred years, it is very likely no one thought it needed to be improved on.

At River City Products, we did not view the lack of heavy vehicle directional stability and other related problems in that manner. Our research established that the lack of heavy vehicle directional stability was a serious drivability problem that needed to be improved on, resulting in the development of The Howard Precision Steer Wheel Directional Control System. It came as a welcome surprise that The Precision Steer Wheel Control System completely solved the puzzling long standing steer wheel accelerated tire wear problem, with the savings in steer wheel tire expense more than paying for the system. Thereby all of the other advantages are achieved at no extra cost.

STEER WHEEL TIRE BLOWOUT CONTROLLABILTY

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An additional contribution to highway safety, of considerable importance that is achieved by The Precision Steer Wheel l Control System, is the amazing improvement in heavy vehicle controllability during steer wheel tire blowouts. A substantial number of verifiable steer wheel tire blowouts have

occurred on trucks and buses that were equipped with the Precision Steer Wheel Control System. The drivers reported easy straight-line controllability in every such event. Out-of-control accidents due to steer wheel tire failure should not occur on heavy vehicles using the Precision Steer Wheel Control System.

THE LONG SOUGHT AFTER SOLUTION TO THE COSTLY

STEER WHEEL TIRE WEAR PROBLEM

The long sought after solution to the costly steer wheel tire wear problem has been completely solved by the new cost effective technology. The Precision Steer Wheel Control System solves the costly steer wheel tire wear phenomenon that has long been a puzzling problem to the heavy vehicle industry. A major tire leasing company first noticed the amazing improvement in steer wheel tire mileage on trucks equipped with the Precision Steer Wheel Directional Control System. The leasing company became interested and conducted an independent investigation comparing the trucks with and without the Precision Steer Wheel Control System. These tests verified an amazing improvement in steer wheel tire service life of over sixty-five percent. Additional tests conducted by over-the-road truck and bus operators using the Precision Steer Wheel Control System, established a sixty to seventy thousand mile improvement in steer wheel tire service life. All of the heavy vehicles using the New Precision steer Wheel Directional Control Technology have a

smooth non-cupping steer wheel tire wear pattern without a trace of the costly irregular wear pattern of the past. Unlike the puzzling steer wheel tire wear problem that has perplexed the heavy vehicle industry for years on end, the explanation for solving the problem is uncomplicated and easy to understand.

First, the costly irregular tire wear pattern only occurs on the front steer wheels due to the unstable behavior inherent to conventional steering geometry.

Second, when the unstable behavior of the steer wheels is prevented by the Precision Steer Wheel Directional Control system, they are made to track directionally stable with the same perfection as the wheels on the non-steering rear axles. Therefore, the tires have the same normal extended service life as those on the fixed non-steering rear axles.

Glossary of Terms and Mistaken Assumptions

Heavy Vehicle Directional Stability: Directional Stability describes a vehicle that has an inherent tendency to remain unvarying on course by resisting lateral forces from the wind and road that require driver steering corrections to maintain directional vehicle control (see pages 3 & 8).

Driver Oversteer: Heavy Vehicle Driver Oversteer is the term for reactive driver steering input that exceeds the amount for safe vehicle control. Over controlled catastrophic roll over highway accidents are more likely to happen to heavy vehicles lacking in directional stability because they are more conducive to driver oversteer.

Crosswind Driving Fatigue: The primary cause of Crosswind Driving Fatigue is the unstable behavior of the castered steer wheels that steer downwind in response to the lateral crosswind gusts (see page 7).

Road Wander: Road Wander is the term heavy vehicle drivers use to describe the lack of heavy vehicle directional stability that requires an inordinate amount of driver steering corrections to maintain vehicle control. It is caused by the lack of inherent precision on-center control of the steer wheels (see page 8).

Steering Wheel Pull: Steering Wheel Pull is the descriptive term heavy vehicle drivers use to describe the tendency of a directionally unstable heavy vehicle to steer to the low side of a crowned or slanted road, requiring counteractive steering wheel pressure to prevent the vehicle from leaving the road (see pages 6 & 7).

Empirical Knowledge: Empirical Knowledge is based on experimental observation rather than scientific methods of establishing accurate conclusions. Therefore Empirical Knowledge has the potential for mistaken assumptions that lead to faulty conclusions.

Mistaken Assumptions About Steer Wheel Castering: The Mistaken Assumptions About Steer Wheel Castering is a classic example of long term faulty empirical knowledge (see pages 3 & 4).

Turning Lift Effect: The function of the Turning Lift Effect is to achieve steering wheel returnability after turning (see pages 5& 6).

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A WORD TO THE WISE IS NOT ALWAYS SUFFICIENT

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The old saying that "If People Knew Better, They Would Do Better," is wishful thinking. A more accurate old saying is "That Which Is Everyone's Responsibility is No One's Responsibility." As the size, weight and speed of heavy over-the-road vehicles increased, directional stability became a more serious need. It was not for the lack of capable engineering that the problem wasn't solved. The heavy vehicle design community is renowned for its technical accomplishments related to the function and reliability of heavy over-the-road vehicles. With all of the serious operational problems that are caused by the lack of steer wheel directional stability, listed on pages 1 and 2 herein, the long standing design oversight was perpetuated because of the status quo syndrome throughout the heavy vehicle industry. Quote, "If It Ain't Broke Don't Fix It" and "Anything We Can Leave Off Won't Cost Anything And It Won't Cause Any Trouble."

The term "Directional Stability" is noticeably absent in the heavy vehicle

vocabulary. There is, however, a typical knee-jerk reaction to the idea of adding to the production cost with something "Not Invented Here." One chief engineer of a major truck company was quick to tell an investigative reporter that heavy trucks needed no improvement. They were easy to steer, giving credibility to the way the lack of heavy vehicle directional stability has been dealt with over the many years, by advancing the state of the art in driver friendly steering , thereby, the heavy vehicle directional control problem is solved by repetitive steering corrections from the vehicle driver, resulting in a major cause of driving fatigue and related highway safety issues.

Some of the major truck lines that have been testing the Precision Steer Wheel Control System have found the driver response to directional stability highly encouraging. They have therefore requested that the manufacturers only quote on new trucks that include the Howard Precision Steer Wheel Directional Control System. Additional truck lines are conducting their own tire mileage verification test.

This Proves That Sometimes A Word To The Wise Is All It Takes.

THE MOST DIRELY NEEDED

HEAVY VEHICLE PRODUCT IMPROVEMENT

· This document presents more in-depth accurate information on improving highway safety by advancing the state of the art in heavy vehicle directional stability than any other known publication.

· The Howard Precision Steer Wheel Directional Control System is presently in service on thousands of heavy over-the-road buses, trucks and recreational vehicles that have collectively been driven more than a hundred and fifty million in-service miles.

· Hours of Service Considerations

Before the development of heavy vehicle directional stability with Precision Steer Wheel Control Technology, the Driver Fatigue studies were based on suitable driver time off and adequate driver rest. The possibility of achieving a substantial reduction in driving fatigue was not considered at the time. The Driving Fatigue studies that have been conducted with directionally stable trucks are very encouraging and may very well have a favorable influence in the Hours Of Service Rules in the future.

· No other product improvement solves so many costly heavy vehicle operational problems (see pages 1 and 2 for details).

· No other direly needed heavy vehicle product improvement is more than paid for by savings in operating cost.

· As a beginning the Howard Precision Steer Wheel Directional Control System will be offered by some manufacturers as an optional equipment item to heavy vehicle operators who request it.

As the size and pulling power of pickup trucks has on some models been increased to 20,000 pounds, the size and weight of the trailers will grow accordingly. Thereby, the lack of directional stability on the many thousands of such vehicles will add significantly to the highway safety problems. The problem can easily be solved by adding the Howard Precision Steer Wheel Directional Control system.

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This Document Can Be Found At www.hpcss.com

This Document Presents More In-depth Accurate Information On Improving Highway Safety By Advancing The State Of The Art In Heavy Vehicle Directional Stability Than Any Other Known Publication

More than ten years and millions of dollars has been invested in developing and testing the Howard Precision Steer Wheel Control Technology that achieves the ultimate in heavy vehicle directional stability. By controlling the steer wheels in the on-center position with a level of precision that is new to the industry, the new technology solves the long-standing industry oversight regarding the unstable behavior of the steer wheels that requires an inordinate amount of repetitive driver steering corrections to maintain directional control of the vehicle, resulting in the primary cause of driving fatigue.

For A More Indepth Overview Of The Long-Standing Heavy Vehicle Design Oversight

The Surprising Number Of Heavy Vehicle Operational Problems That Are Solved With the Precision Steer Wheel Control Technology ..........................................................pages 1 & 2

The Critical Need For Heavy Vehicle

Directional Stability.......................................................page 3

The Widely Misunderstood Adverse Effects

Of Steer Wheel Castering...................................... page 6 & 7

Steer Wheel Tire Blowout Controllability, And

The Long Sought After Solution To The

Costly Steer Wheel Tire Wear Problem.........................page 9

For additional information please contact

River City Products, Inc. • 199 W. Rhapsody • San Antonio, TX 78216

Phone: 210-377-0853

3-03-04