Land vehicles – Wheeled – Articulated vehicle
Reexamination Certificate
2002-08-22
2003-08-12
DePumpo, Daniel G. (Department: 3611)
Land vehicles
Wheeled
Articulated vehicle
C280S414500, C280S442000, C280S137500
Reexamination Certificate
active
06604753
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a steering process which allows long vehicles to make sharp turns. More specifically, the present invention pertains to a rear wheel steering process for long vehicles, including among others, trucks, busses, stretch limos, and semi-tractors and trailers, enabling their vehicles to safely and easily clear the curb when making sharp turns on narrow city streets.
2. Description of the Related Art
Presently, long vehicle turns in tight situations can be quite dangerous. For example, when turning from one city street to another, the driver of a large trailer rig must begin the turn in the second lane over from the curb, thus taking up both lanes of traffic, in an effort to prevent the rear tandem wheels of the rig from running over the curb and perhaps up on the sidewalk. Similarly, long vehicle turns across four lane intersections can be dangerous. If the trailer is crossing a four lane road, it may take two lanes into the intersection, and take two lanes as it turns.
If the semi is pulling two trailers, the above problem is compounded. In such a situation, the semi turns into the intersection, the first trailer cuts across the curb, and the second trailer crosses on the sidewalk. Long trucks, busses and stretch limos, like the trailers, also must take more than their share of the road when turning sharp corners.
There have been several attempts to overcome the above disadvantages. Some long ladder fire trucks and ladder trailers have a seat and steering wheel over the rear wheels, and a fireman steers the back wheels so as to miss the curb. Steering the back wheels of a vehicle is old art. An early automobile had both front and back wheels that were steerable. Yet, directly steering the rear wheels of a vehicle has its share of problems as well, including the need of an additional driver, just to name one.
It would be beneficial to provide a rear wheel steering system that a single driver can operate by the push of a button. Such a system would improve truck hauling safety. In view of the prior art it can be seen that there is a need for a modified rear wheel steering system for long vehicles. It is to the provision of such a system that the present invention is primarily directed.
BRIEF SUMMARY OF THE INVENTION
The present invention is a rear wheel steering process that enables a long vehicle to make tighter turns than are possible with conventional steering assemblies. The present rear wheel steering system requires only minimal intervention by the driver, and allows the trailer-rig, truck or bus to make sharp turns without crossing into the other lane, yet providing for the rear wheels to miss the curb.
The present rear wheel steering process comprises a control system and a rear wheel guidance system. The control system is capable of automating the steering process of the rear wheels, while the rear wheel guidance system is capable of defining the path for the rear wheels to follow. Preferably, the rear wheel guidance system comprises a guide control wheel that lowers to the travel surface in response to the control system. The rear wheel guidance system can further comprise a gyrocompass assembly housed on a pivotal rear wheel unit.
The description of the present invention will include specific references to a tractor-trailer vehicle type, but it will be understood that the steering system is useful in all manner of vehicle types that incorporate rear wheel assemblies.
Further, the term “centerline” will be used in references with the vehicle and the wheels of the vehicle, and will be understood to mean as described below. The term “vehicle lengthwise centerline” will refer to the centerline of the vehicle in its direction of travel. For example, when describing a semi, the tractor-trailer lengthwise centerline will be the centerline running between the front and back ends, from the cab to the end of the trailer.
Similarly, the centerline of a particular wheel of the vehicle will refer to the centerline of the wheel in its direction of travel. Thus, for example, in a “normal driving state”, wherein the semi is traveling general straight down the road, the tractor-trailer lengthwise centerline, and all the centerlines of the wheels, would be in generally parallel orientations. It will be understood that if a particular wheel of the vehicle is pivotally enabled on the vehicle, the centerlines of the vehicle and wheel may not always be generally parallel. For example, in a turn (or “turning state”), the centerline of the vehicle may rotate out of alignment from the centerline of the pivotal wheel. If the rear wheel(s) of a vehicle were pivotal, and the front wheel(s) of the vehicle were to initiate a turn of the vehicle, while the centerline of the vehicle rotated along the radius of the turn, the rear wheel, free to pivot, might continue to travel in the direction of the vehicle before the turn, because of surface friction, before the rear wheel would rotate into the turn.
Likewise, the “rear wheel unit centerline” may, or may not, lie on the lengthwise centerline of the cab. During normal hauling, the centerlines would lie on atop the other. But when the rear wheel unit pivots relative to the length of the trailer, the rear wheel unit lengthwise centerline will similarly angle away from the trailer's lengthwise centerline.
The present steering system has a “normal driving state” and a “turning state”. In the normal driving state, the rear wheels are locked in alignment with the vehicle's centerline, like any standard trailer. The normal driving state is the typical highway hauling use of the vehicle. As the long vehicle approaches a sharp turn, the driver of the vehicle activates the control system of the rear wheel steering system from the normal driving state to the turning state, wherein the rear wheels are then steerable.
Preferably, the invention is a process of rear wheel steering for a vehicle traveling on a driving surface comprising the steps of resisting the rear wheels from pivoting during the normal driving state so the centerline of the rear wheel remains generally parallel to the centerline of the front wheel. In this way, during highway driving, for example, the rear wheels of the semi can be locked from free pivot. Upon initiation of a turn, the invention maintains the rear wheels in a straight line of travel, although the vehicle has begun to turn on its front wheels. This step of the invention comprises guiding the pivoting of the rear wheel upon entrance of the turning state, and preferably includes the lowering of a guide control wheel. At a preset condition, the rear wheels are then freed from guidance prior to exit of the turning state, so the rear wheels may now pivot, and the vehicle complete the turn.
The control system of the present invention determines when to initiate the step of guiding the pivoting of the rear wheel, and preferably when to initiate the step of freeing the rear wheel from guidance.
The rear wheel(s) of the vehicle may be located on a rear wheel unit. The pivotal rear wheel unit enables the rear wheels to turn through a turning angle about the lengthwise centerline of the vehicle. In city driving applications, the wheels may be powered by fluid cylinders, electric motors or other standard means.
While the vehicle is on the straight highway, the system is in the normal driving state, and the present system is deactivated. The driver can then activate the system via the control system when entering a turn. Upon activation of the present system, the rear wheel guidance system will lower a guide control wheel to safely keep the rear wheels in alignment as the trailer makes its turn down the side street.
If the tandem rear wheel unit is free to pivot on the trailer, it will guide itself straight down the road, without any other means of guidance. However, one cannot safely steer the wheels in this manner. The reason is that if one set of the tandem's wheels are on dry pavement and the other set is on a wet road or ice and t
DePumpo Daniel G.
Schneider, Esq. Ryan A.
Troutman Sanders LLP
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