Land vehicles – Wheeled – Coasters
Reexamination Certificate
1996-07-03
2001-02-27
Culbreth, Eric (Department: 3611)
Land vehicles
Wheeled
Coasters
C016S03500D, C280S011231, C280S011280
Reexamination Certificate
active
06193249
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to turning mechanisms for wheeled vehicles. The invention is specifically concerned with those turning mechanisms capable of being adapted to tandem wheeled vehicles.
Many attempts have been made in the past to incorporate turning capabilities in vehicles equipped with tandem wheels. In general, vehicles equipped with tandem wheels are incapable of turning while all the wheels are on the ground. In-line roller skates, for example, suffer from this inconvenience. Typical in-line roller skates employ an arrangement in which three to five wheels are placed in tandem. One of the biggest drawbacks of the in-line roller skate is that the operator is incapable of making right or left turns during single foot skating. Skateboards typically overcome this problem by employing a plurality of suspension frames which carry a wheel on either side, Turning is subsequently accomplished by movement of the suspension frame and not the wheels themselves. A variety of spring and tension assemblies have been employed by the prior art to control the turning of wheels in vehicles where the wheels are in tandem, but these devices are often complicated and difficult to manufacture economically. Accordingly, a simple and inexpensive turning mechanism would be beneficial for tandem wheeled vehicles.
Several designs have been proposed by the prior art to eliminate the problems associated with the turning of tandem wheeled vehicles. For example, U.S. Pat. No. 5,398,949 discloses a roller skate having a steering mechanism which allows the operator to execute figure skating maneuvers. The roller skate includes a steering cushion mechanism and a pivotal-turntable brake wheel mechanism. The steering cushion mechanism utilizes either a combination of screws and springs, or resilient members in conjunction with the axle of each wheel. In certain instances, a combination of resilient members, screws, and springs is utilized. However, the mechanism is still somewhat complicated because the frame must be designed to accommodate all of the additional parts.
U.S. Pat. No. 4,382,605 shows a steering mechanism for tandem wheeled vehicles. The mechanism includes a frame to which a pair of suspension members is attached. Two subsuspension members are also attached to the frame, one at each point of attachment of the suspension members. Each subsuspension member carries two wheels. The subsuspension members allow their respective sets of wheels to turn and follow a curved path dictated by the operator. However, the steering mechanism requires the addition of a suspension member and a subsuspension member, both of which must be attached to the base. These additional members increase the number of parts and create a more complex system.
U.S. Pat. No. 1,778,850 shows a roller skate suitable for figure skating. The roller skate includes a main wheel which is centrally positioned below the skate and a pair of auxiliary wheels, such as casters, at the front and rear positions of the skate. The auxiliary wheels are typically of smaller diameter than the main wheel and capable of swivelling. However, the auxiliary wheels are free to swivel uncontrolled, thereby creating an imprecise control system.
While the foregoing arrangements address the need for providing simple and inexpensive turning capabilities to tandem wheeled vehicles, the problem persists. Most of the prior art focuses on arrangements suitable only for roller skates and figure skating. Others are unable to adequately provide a mechanism that is simple and easy to manufacture. Consequently, it remains difficult to turn tandem wheeled vehicles.
OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, it is an object of this invention to overcome the disadvantages of the prior art.
It is another object of this invention to provide a steering mechanism for tandem wheeled vehicles.
It is yet another object of this invention to provide a steering mechanism for tandem wheeled vehicles which is simple in design.
It is yet another object of this invention to provide a steering mechanism for tandem wheeled vehicles that is inexpensive to manufacture.
In accordance with the objects of this invention, a turning mechanism is provided for vehicles equipped with tandem wheels. The turning mechanism includes a base with a bottom surface to which a caster is mounted. The caster includes an axle and a wheel which is mounted on the axle. Since casters are well known in the field, a detailed description of casters and their components will not be provided. Only the parts essential to providing an understanding of the invention are described. A pair of rotation limiters having resilient properties is positioned with each rotation limiter on one side of the caster. Each rotation limiter is attached at one end to the respective end of the axle corresponding to its position on the side of the caster. The opposite end of each rotation limiter is attached to the bottom surface of the base. Each of the rotation limiters applies a tension force to one side of the caster. The tension force applied by each individual rotation limiter is equal and the tension tends to force the caster to swivel in the direction of that particular rotation limiter. Since this tension force is equal for each of the rotation limiters, the net result is that the two tension forces cancel each other and the caster remains in a straight orientation.
In order to execute a turn, the base is tilted in the desired turning direction. This action forces the caster to swivel in the same direction. The force applied by the tilted base also increases the tension on one of the rotation limiters; the one opposite of the turning direction. This increased tension acts on the caster to reduce the degree of swivelling which would freely occur.
The rotation limiters provide a certain level of stability to the overall operation of the steering mechanism. First, the rotation limiters maintain the caster in a straight orientation. Next, the rotation limiters prevent the caster from swivelling excessively during turns. In order to accomplish this task, it is evident that there are a variety of materials with resilient properties that are capable of being substituted while performing the same function. For example, a band having elastomeric properties may function as a rotation limiter. As yet another example, a spring could also function as a rotation limiter.
In one embodiment of the invention, the turning mechanism is provided with a mounting plate attached to the bottom surface of the base. The mounting plate provides a reinforced surface for attaching the caster. This may be necessary in situations where the material from which the base is constructed is incapable of withstanding the forces that will act upon it during regular operation.
In an application of the invention, a skateboard is equipped with the turning mechanism. The skateboard includes a base which has a bottom surface, a front portion, and a rear portion. A first caster is rotated so that it is facing forwardly and positioned at the front portion of the base. The first caster is then secured to the bottom surface of the base. The first caster includes a first axle and a first wheel which is mounted on the first axle.
A first pair of rotation limiters is positioned with each rotation limiter on one side of the first caster. Each of the first pair rotation limiters is attached at one end to the corresponding end of the first axle. The opposite end of each of the first pair of rotation limiters is attached to the bottom surface of the base. The rotation limiters are preferably selected such that they have resilient properties. Each of the first pair of rotation limiters applies a tension force to the first caster which urges it to rotate in the direction of the rotation limiter. The tension forces applied by each of the first rotation limiters react with each other and cancel. The net result is that the first caster remains in a straight orientation when the base is in a horizontal position.
A second caster is rotated so
Culbreth Eric
The Bilicki Law Firm P.C.
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