Abstract:
A bumper rail assembly is provided that uses bars of arch-shaped spring steel, mounted in a standing-arch configuration, as shock absorbers for the bumper rails. An end portion of the spring steel bar is shaped into a saddle so that the spring steel bar can be secured indirectly, by means of a metal plate or bracket, to the concrete base. The assembly minimizes shear forces on the anchor bolts, offers performance advantages over conventional shock absorbers such as used tires, and is economically competitive with conventional shock absorbers.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates generally to bumper rails, and more particularly to shock absorbers for bumper rails. 
       BACKGROUND OF THE INVENTION 
       [0002]      FIG. 1  illustrates a go cart track  5  with two bumper rails  6  extending around both sides of the full length of the track  5 . A common bumper rail  6  is configured to deflect when impacted by a cart and comprises a steel band, or suitable material, with an approximate 5-inch by 0.625-inch cross section. The bumper rails  6  are commonly backed by used automobile tires  3  or other rubber devices that serve as shock absorbers for the rails  6 . 
         [0003]    Tires perform their function reasonably well, as long as the impact load on the rail system is low or moderate. But in areas of the track that receive frequent high-load impacts, the tires often become permanently deformed, particularly when the impact loads exceed the elastic limit of the tires. Eventually, the elasticity of many tires decay so much that the tires are rendered crumpled and useless.  FIG. 2  illustrates some tires in the early stages of this deformation process. 
         [0004]    After a tire is spent, it is common to remove the tire, re-straighten the bumper rail, and install a new tire. This type of maintenance may have to be performed many times depending on the track design and usage. 
         [0005]    Despite these inconveniences, used tires are relatively cheap and easy to obtain and relatively easy to install. These and other factors have served to suppress prior art motivation to replace the tires with a different shock absorbing system. 
         [0006]    One of the Applicants owns a small amusement park that includes a go cart track. Applicants, moreover, enjoy making innovations even in areas where a person of ordinary skill, content with conventional techniques, might lack any motivation to innovate. This drive led Applicants to explore replacing tires with leaf springs similar to auto leaf springs. 
         [0007]    Applicants&#39; investigations made them aware of one prior art leaf-spring-based shock absorbing system installed at a track in Florida. The system, which is herein referred to as the “Shaller design,” is illustrated in  FIG. 3 . The Shaller design replaces each tire  3  with an arch-shaped leaf spring  90  installed lying on its side—that is, with its radial cross-section in a horizontal (non-upright) position. One end of the arch-shaped leaf spring  90  is welded to a sleeve  99  which is secured to the concrete base  2  by an anchor bolt  91 . 
         [0008]    Although Applicants were informed that the Shaller design performed well, Applicants also realized that it was relatively expensive to fabricate. So Applicants conceived, tested, and refined alternative systems. Applicants tried different leaf spring sizes, configurations (including a “V” shaped design), and fastening alternatives. Many of Applicants&#39; experimental designs resulted in failures where the spring was anchored to the concrete base, due to the intense side bending loads imposed on the concrete anchor. After repeated refinements, Applicants developed a design that is both economical and robust. 
       SUMMARY OF THE INVENTION 
       [0009]    A spring is provided as a shock absorber for a bumper rail system. The spring—preferably but not necessarily taking the form of a four-inch by one-quarter-inch bar of 5160 spring steel—is shaped into an arch configuration and mounted in a standing arch configuration. An end portion of the spring bar is shaped into a saddle so that the spring bar can be secured indirectly, by means of a metal plate or bracket, to the concrete base. 
         [0010]    The current invention has proven not only to be more effective and robust than used tires, but also competitive in price. The invention is easy to fabricate and easy to install. 
         [0011]    Additional advantages of the present invention—which were not apparent when conceptualizing the design but which became apparent after testing of the invention—included (1) the ability to add more springs between existing ones in high impact areas and (2) the practicality of re-straightening the springs when they become over-stressed. Other environmental, maintenance, and financial benefits include (3) potential savings on new track installations, (4) the ability to retrofit existing tracks while using the same bolt that was used to secure the tire to the rail to secure the spring to the rail; (5) the avoidance of having rainwater and debris collect inside the tires, (6) the fact that it is more feasible to recycle spent steel than spent tires, and (7) the fact that spent steel can be sold at a small profit for scrap, whereas spent tires require a disposal fee. 
         [0012]    Part of what makes the present invention so innovative and remarkable is its simplicity and economy. It comprises only a few different parts and is easy to use. But despite its simplicity, the present invention provides numerous advantages over conventional approaches. Those of ordinary skill in the art will appreciate these and other improvements described further below in the detailed description and the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  illustrates a go-cart track with used tires employed as shock absorbers for the rails. 
           [0014]      FIG. 2  illustrates a portion of a go-cart track with used tires employed as shock absorbers for the rails. 
           [0015]      FIG. 3  illustrates a portion of a go-cart track with shock-absorbing leaf springs lying on their sides and secured to the concrete base of the track by an anchor-bolt sleeve welded to the spring. 
           [0016]      FIGS. 4-6  illustrate a portion of a go-cart track with one embodiment of a bumper rail assembly according to the present invention, including shock-absorbing springs mounted in a standing arch configuration and a saddle for anchoring the springs to the concrete base. 
           [0017]      FIG. 7  is a side view of one embodiment of an arch-shaped spring configured in accordance with the present invention. 
           [0018]      FIG. 8  is a perspective view of one embodiment of an arch-shaped spring configured in accordance with the present invention. 
           [0019]      FIG. 9  is a top view of a bar of spring steel before it is formed into the arch-shaped spring of  FIG. 8 . 
           [0020]      FIG. 10  is a top view of the bar of  FIG. 10 , showing a drilled hole location and lines along which the bar is bent to form the saddle portion and the opposite end portion. 
           [0021]      FIG. 11  is a side view of the bar of  FIG. 9 . 
           [0022]      FIG. 12  is a side view of the bar of  FIG. 10 , after the saddle and opposite end portions have been bent. 
           [0023]      FIG. 13  is a perspective view of one embodiment of an anchor bracket. 
           [0024]      FIG. 14  is a perspective view of one embodiment of the arch-shaped spring and bracket assembly. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]      FIGS. 4-6  illustrate one embodiment of a bumper rail assembly  9  for a go cart track  5 . The bumper rail assembly  9  comprises a track rail  6  in the form of a metal band extending along and near an edge of the track  5 . The track rail  6  has an outer side  7  facing away from the track  5  and an inner side  8  facing the track  5 . The bumper rail assembly  9  is configured to resiliently deflect impacts from go carts. A plurality of bumper rail springs  10 , each taking the form of an arch- or arcuate-shaped leaf spring, back up the track rail  6 . Each bumper rail spring  10  is coupled to and positioned in a standing arch configuration on the outside  7  of the track rail  6 . 
         [0026]    Each arch-shaped spring  10  is fastened to the track rail  6  by means of a fastener  11  that secures a first end of the spring  10  to the track rail  6 . The fastener  11  will often be a bolt  12  ( FIG. 14 ) that is welded to the track rail  6 , which penetrates a hole  55  ( FIG. 10 ) in the first end of the spring  10 . The bolt  12  is secured to the spring  10  by a nut  13  ( FIG. 14 ). In retrofitting situations, the fastener  11  is preferably the same bolt  12  that had been used to secure a tire  3  or other shock absorber. 
         [0027]    An anchor  15  indirectly secures the second end, opposite the first end, of the spring  10  to a concrete base  2  that extends alongside the perimeter of the track  5 . In preferred embodiments, the second end of each arch-shaped spring  10  is formed in the shape of a saddle  30  ( FIG. 8 ), including a bracket or saddle seat  35  and an upturned section  36  ( FIG. 7 ). An anchor bracket  70  ( FIGS. 13-14 ) straddles the saddle  30  to secure the spring  10  to the concrete base  2 . In its simplest form, the anchor bracket  70  comprises a rectangular, planar metal plate ( FIG. 13 ) with a thickness N of about one-half an inch, sides  73  and  74  each having a length L of about six and three-eighths inches, and sides  71  and  72  each having a width M of about two inches. The anchor bracket  70  also includes two nine-sixteenth-of-an-inch-diameter holes  78  and  79  spaced about 4.25 inches apart and otherwise centered in the bracket  70 . The anchor bracket  70  is secured to the concrete base  2  by two concrete anchor bolts  80  and nuts  81 . 
         [0028]    In stating that the anchor  15  indirectly secures the spring  10  to the concrete base  2 , Applicants mean to contrast the anchor  15  from systems that would incorporate a bolt that is inserted through a hole in the spring  10  or through a sleeve or other device welded to the spring  10 . 
         [0029]    The saddle  30  and bracket  70  configuration gives the second end of the spring  10  some play to move laterally with respect to bracket  70  as the spring  10  receives strong compressive forces. The upturned section  36  also accommodates upward deflection of the first end of the spring  10 . 
         [0030]    The saddle  30  and bracket  70  configuration also converts some of the spring compressive force that would otherwise tend to shear the bolts  80  into a tensile force against the bolts  80 . Applicants&#39; experimentation has shown this configuration, on the whole, significantly reduces the problem of anchor bolts  80  being sheared. 
         [0031]      FIGS. 7-12  illustrate the dimensions and formation process of one preferred embodiment of the bumper rail spring  10 . 
         [0032]    To form the bumper rail spring  10 , an elongate flat rectangular bar  50  ( FIGS. 9 ,  11 ) of steel is obtained. In a preferred embodiment, the bar  50  is made of spring steel, and more particularly, 5160 carbon-chromium spring steel. Spring steel is a low alloy, medium carbon steel with a very high yield strength. Objects made of spring steel can return to their original shape despite significant bending and twisting. The bar  50  has a top face  57 , a bottom face  56 , a rail-proximate end  53 , a rail-distal end  54 , and opposing sides  51  and  52 . The bar  50  has a length G of between 2 and 4 feet—in one embodiment approximately 33.5 inches—a width F of approximately four inches, and a thickness E of approximately one-quarter of an inch. The dimensions may be varied somewhat, but Applicants have found through experimentation that the bar  50  should have a cross-sectional surface area substantially greater than 0.5 square inches. As shown in  FIG. 10 , a single hole  55  having a diameter H of about five-eighths of an inch is drilled about one inch from the rail-proximate end  53 , centered between sides  51  and  52 . The hole  55  is meant to accommodate a pre-existing anchor bolt  12  ( FIG. 14 ) welded onto the steel band of a go-cart track. 
         [0033]    As illustrated in  FIG. 12 , a rail-proximate end portion  25  of the bar  50 , having a length D of about 2 inches, is bent along line  61  downward at an angle I of between about 3 and 10 degrees. A short section of the opposite end of the bar  50 , having a length C of about 1.25 inches, is bent upward along line  63  at an angle K of about 20-45 degrees to form the upturned section  36 . An adjoining section, having a length B of about 2 inches, is bent upward along line  62  at an angle J of about 75 to 90 degrees, to form the saddle seat section  35 . 
         [0034]    Finally, a long intermediate section  59  spanning about 28 inches between lines  61  and  62  is bent convexly—from the perspective facing the front face  57 —into an arch  20  having a radius A of approximately 9 inches. The arch does not have to be entirely circular or elliptical. Indeed, it may be skewed so that the portion of the arch  20  closest to the saddle  30  has a flatter curve. 
         [0035]    The present invention also contemplates the following method of improving a go-cart track  5  having a track rail  6  braced with tires  3  or other shock absorber to absorb shock. The method comprises the steps of removing one of the tires  3  or other shock absorbers and replacing it with an arch-shaped spring  10 . The arch-shaped spring  10  is formed from a bar  50  of spring steel, a section of which has been shaped into an arch  20 , and another section of which has been shaped into a saddle  30 . The spring  10  is mounted in a standing arch configuration to the bumper rail  6  and a concrete base  2 . The bar  50  is indirectly anchored to the concrete base  2  by an anchor bracket  70  that straddles the saddle  50  and which is secured to the concrete base  2  by bolts  80 . 
         [0036]    Although the foregoing specific details describe various embodiments of the invention, persons reasonably skilled in the art will recognize that various changes may be made in the details of the apparatus or method of this invention without departing from the spirit and scope of the invention as defined in the appended claims. 
         [0037]    The present invention includes several independently meritorious inventive aspects and advantages. Unless compelled by the claim language itself, the claims should not be construed to be limited to structures that incorporate all of the inventive aspects, or enjoy all of the advantages, disclosed herein.