Abstract:
A truck tractor fifth wheel for semi-trailer trucks includes a built-in structure and mechanism for supporting and deploying a T-shaped retaining activation bar. The bar is carried underneath the fifth wheel and is supported on side walls of a support block cast integrally with the fifth wheel body. Upon being deployed in a jackknifing situation, an end of the bar comes into contact with a stop block underneath the trailer. Anti-jackknifing components are included in the fifth wheel design from the outset, thus avoiding difficulties associated with after-market installation of such components. Integral casting of components provides increased strength of the overall structure.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to apparatus for preventing jackknifing between tractors and connected trailers of semi tractor trucks.  
         BACKGROUND OF INVENTION  
         [0002]    A continuing problem arising in connection with operation of semi trailer trucks is the tendency of these vehicles to become jackknifed under certain conditions. Tractor and trailers are conventionally coupled together by a fifth wheel on the tractor in which a kingpin secured to the trailer is pivotally received. This coupling enables the tractor to pull the trailer and provides for relative pivotal movement for maneuvering the vehicle. Jackknifing occurs when the trailer pivots relative to the tractor to an extent such that the operator can no longer maintain or recover control over the vehicle. Typical driving conditions, which may cause jackknifing, are those in which the tractor wheels are made to lock and slide or to spin: in either case, the direction of the wheel can no longer be controlled, and it takes the path of least resistance. Improper braking or steering and accelerating or decelerating too fast can all cause jackknifes, especially on roads made slick by rain, snow, or ice. Anti-jackknifing arrangements have been developed to prevent or minimize jackknifing action by limiting the allowable pivotal movement between the tractor and trailer. Various anti-jackknifing devices for installation on trailer trucks are disclosed in prior patents. In general, these devices include a first stop retractably mounted on either the fifth wheel or on a wear plate under the trailer and a pair of cooperative stops mounted spaced apart on the other of these members. The pair of stops limits pivotal, movement beyond a predetermined angle when engaged by the first stop. These prior devices in general present a disadvantage in that they require cutting into the fifth wheel of the tractor and/or the wear plate of the trailer in order to provide necessary slots or recesses for operation of the movable stop members. This requirement makes installation of components on the fifth wheel and trailer difficult, and the resulting slots or recesses may substantially reduce the strength of the fifth wheel and trailer plate, in effect compromising the design and creating weak points susceptible to U.S. Pat. No. 4,991,863, issued Feb. 12, 1991 to the present applicant failure and which is hereby expressly incorporated by reference, largely avoids cutting into existing parts to provide slots or recesses but instead employs a framework of supporting gussets welded to the forward end of the fifth wheel and a forwardly extending plate outside the periphery of the fifth wheel. A latch block is pivotally mounted to the support frame and arranged for upward movement between gussets and into position to come into contact with stop blocks on the trailer. While this apparatus has been demonstrated to be effective, it has not found acceptance in the market place. Welding of a framework of gussets to the fifth wheel is considered enough of a change to cause concerns about an impact on pre-existing designs, as well as potential liability and insurance problems. In view of difficulties inherent in considering anti-jackknifing devices as being appropriate for treatment as “add-on” or after market equipment, applicant has concluded that a better approach is to provide an entirely new design in which anti-jackknife capability and components are included in the fifth wheel and trailer structure from the outset. This could overcome obstacles to acceptance as discussed above and would promote wider use to an important safety measure.  
         SUMMARY OF THE INVENTION  
         [0003]    The present invention is directed to an anti-jackknifing system operative to limit allowable pivoting motion between a fifth wheel mounted on a tractor and a trailer coupled to the fifth wheel by a kingpin. A T-shape retaining activation bar is carried at the forward end of the fifth wheel in position for being deployed above the plane of the fifth wheel so that ends of the bar will come into contact with stationary blocks placed on the underside of the trailer at prescribed angular locations. All necessary structure for supporting both the bar and for supporting all necessary components to bring about deployment are cast in place in the fifth wheel body, thus avoiding subsequent steps such as cutting slots in the fifth wheel or welding extensions or supporting gussets to it. As a result questions regarding integrity of the fifth wheel design upon adding anti-jackknifing capability will not be presented.  
           [0004]    The fifth wheel of the present invention may have a generally circular shape at its forward end and a forked configuration at the rear to allow connection to a kingpin. Overall the fifth wheel has an inverted pan structure; with a flat upper contact surface and shallow sidewalls around its periphery perpendicular to the flat surface. To enable support for the retaining activation bar and components required for its deployment a support block including a mount is provided in a position spaced forward from the fifth wheel center and a pair of side support walls are placed for defining a pocket at the forward end of the fifth wheel. The side support walls have apertures for receiving a pivot pin, and the space between the walls is configured to allow necessary movement of the rear end of the bar. The location of this pivot pin is inside the circular periphery of the fifth wheel, thus allowing for shorter, more compact connecting rods and other components, in contrast to the prior arrangement where support was provided by an extension plate well forward of the fifth wheel periphery. Other features normally included in fifth wheels for purposes unrelated to prevention of jackknifing are also provided in the cast fifth wheel. In particular a pair of aperture tabs at both side walls for connection to pins that ride in bearings of support blocks attached to a tractor frame, a stabilizer bar connected to rear positions of forked legs of the fifth wheel and a slanted, thinner portion at ends of the legs to facilitate hook-up movement.  
           [0005]    Inclusion of all features necessary to accommodate and support anti-jackknifing components in an integral cast fifth wheel at the outset enables these aspects to be given full consideration at an early design stage, in contrast to an “add-on” approach, which could compromise the integrity of the fifth wheel. Casting also provides better strength and wear properties than rolled plate metal. By placement of the pivot pin supporting the rear leg of the activation bar inside the periphery of the fifth wheel a shorter more stable mechanism is obtained.  
           [0006]    It is therefore an object of this invention to provide an anti-jackknifing system using a cast fifth wheel including in the casting features for support of deployable components.  
           [0007]    Another object is to provide such a system wherein a deployable retaining activation bar is located in a position such that pivoting of the bar around a pivot at its rearward end occurs within the forward periphery of a fifth wheel.  
           [0008]    Another object is to provide a cast fifth wheel including as integral components thereof elements for support of a deployment mechanism.  
           [0009]    Yet another object is to provide a more compact anti-jackknifing system having higher strength.  
           [0010]    Other objects and advantages of the invention will be apparent from the following detailed description and the appended clams. 
       
    
    
     BRIEF DISCRIPTIN OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a pictorial view of the fifth wheel embodying the invention installed on a frame of a truck trailer.  
         [0012]    [0012]FIG. 2 is a partially diagrammatic view taken from below showing a restraining activation bar mounted underneath the fifth wheel of FIG. 1.  
         [0013]    [0013]FIG. 3 is a pictorial view of structure for supporting the fifth wheel.  
         [0014]    [0014]FIG. 4 is a sectional view of the fifth wheel taken along line  4 - 4  of FIG. 2.  
         [0015]    [0015]FIG. 5 is a perspective view of a restraining activation bar as installed on the fifth wheel.  
         [0016]    [0016]FIG. 6 is a perspective view of a pneumatic cylinder for deploying the bar of FIG. 2.  
         [0017]    [0017]FIG. 7 is a side view, practically broken away showing deployment structure in place under the fifth wheel.  
         [0018]    [0018]FIG. 8 is a perspective view taken from below, showing a kingpin and stop blocks installed under a tanker trailer.  
         [0019]    [0019]FIG. 9 is an enlarged view showing details of stop blocks of FIG. 8.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0020]    Referring to FIG. 1 of the drawings, there is shown a fifth wheel  10  mounted to a frame  12  of a tractor disposed for coupling with a trailer. The fifth wheel has front portion:  14  adapted to come into contact with a wear plate underneath the trailer body. Forked legs  16 ,  18  are provided at the rear of the fifth wheel. The legs have downwardly slanting rear portions  20  to facilitate making connecting with the trailer. A slot  22  is defined between the legs and terminates at a kingpin reception end  24 . A stabilizer bar  26  extends across a lower portion of the slot to provide bracing. Side walls  28  perpendicular to flat surface  14  extend downward around the periphery of the fifth wheel.  
         [0021]    Mounting tabs  30 , 32  placed on opposite side walls  28  have an aperture for receiving a pivot pin  34  which connects the fifth wheel to a pair of bearings  52   a ,  52   b  (FIG. 3).  
         [0022]    Spaced apart vertical stubs  36 , 38  having a generally rectangular cross section, are located at a center front edge of the fifth wheel, defining the outer portion of channel  40  for movement of a retaining activation bar (FIG. 2). An inner portion of this channel is formed by a slot  41  in the outer periphery  42  of front portion  14  of the fifth wheel.  
         [0023]    Bearings  52   a ,  52   b  are supported on generally triangular mounting blocks  59   a ,  59   b  are carried on a supporting structure. Longitudinal side frame members  53 , 55  are connected along their length to angle steel bars  43   a ,  43   b  to provide more strength. A lower steel plate  44  extends across the width of the frame and is connected to angle steel bars on both sides. A pair of upper support plates  46   a ,  46   b  is placed on top of the lower plate at end locations. Mounting blocks  59   a ,  59   b  are secured on top of upper plates  46 ,  48 . Bolts as shown by bolt holes  54  may used to make connection of the various plates.  
         [0024]    As Shown in FIG. 2 a T-shaped retaining activation bar  78  is supported under front portion  14  of fifth wheel  10  in a manner such as to facilitate deployment into position to come into contact with a stop block on the trailer when required. The fifth wheel has a supporting rib  56  across its width forward of slot end  24 . A U-shaped support block  58  (FIG. 4) spaced apart forward to rib  56  has a pair of facing side walls  60 ,  62  in between which is located a mount  64 . The mount has a pair of tabs  68 ,  70  that receive a lug  72  of air cylinder  66 . (FIG. 6) An aperture  73  extends through the support block and the mount for placement of a pivot pin  74 . Piston rod  76  propelled by the cylinder has a clevis  80  penetrated by aperture  83  at its outer end for engagement with lug  78 , by means of pivot pin  84 . Middle leg  90  of bar  78  is pivotally mounted on pivot pin  79  extending through side walls  60 ,  62  of support block  58 , well within the outer perimeter of fifth wheel portion  14 .  
         [0025]    [0025]FIG. 4 shows support block  58  with downwardly extending walls  60 ,  62  cast integrally with vertical stubs  36 ,  38  forming a cavity or channel  40  for movement therein of tee  90  of bar  78  and the propelling air cylinder  66 . This arrangement enables a more compact mechanism with highest strength.  
         [0026]    Details of retaining activation bar  78  are shown in FIG. 5, the bar in this view being in inverted position. The bar is T-shaped with a rectangular body portion made up of arms  86  and  88  and intersected by a mounting leg  90 . At its outer end leg  90  has a corner notch  94  defined in its upper face to enable clearance around adjacent components during deployment and retraction. An aperture  92  parallel to the outer end of leg  90  enables passage of a pivot pin  79  connecting the bar to the fifth wheel. Lower edge  93  of the arm is rounded off to further facilitate movement of the bar. Ends  99   a  and  99   b  of arms  86  and  88  each have a corner notch  100   a  and  100   b  at their lower sides to provide for intermeshing with complementary features of stop blocks as will be explained below. Corner surfaces  102   a  and  102   b  are rounded off to enable smooth interlocking action. Contact surfaces  104   a  and  104   b  are arranged to come into flush contact with stop block surfaces when deployed. In its retracted position bar  78  is located below the plane of fifth wheel surface  14 , and when deployed it moves upward into position wherever its upper surface becomes coplanar with the fifth wheel.  
         [0027]    [0027]FIG. 6 shows an air cylinder  66  which may be used for deploying and retracting bar  78 . The cylinder has a lug  72  at its inner end connected to mount  64  by means of pivot pin  74 . A piston rod  76  extends from its outer end and has a clevis  80  for making connection with lug  82  located on the lower side of bar  78 . The cylinder is powered by compressed air delivered from a source (not shown). Sensors  106 , and  108  for measuring angular displacement may be located on the cylinder and held in place by bands  110  and  112 .  
         [0028]    As shown in FIG. 7, restraining activation bar  78  moves upward into deployed position by action of air cylinder  66 , causing pivoting around pin  79 . This location is spaced inside the arcuate periphery of the fifth wheel, which coincides with the inner side of projecting stub  38 .  
         [0029]    Placement of stop blocks on the underside of a trailer is shown in FIG. 8. In this embodiment the trailer  112  is a tanker trailer having a heavy plate positioned at the front end of the trailers, with a kingpin  118  mounted on the plate for engagement with a fifth wheel of a tractor. Side beams  116 ,  116   b  are used to connect the plates to the trailer. Stop blocks  120 ,  122  are connected to the plate at locations such that sides of the blocks will be contacted at surfaces  130  or  131  by a mating surface  104   a  or  104   b  of bar  78  when deployed and when the trailer undergoes pivotal movement beyond a predetermined angle.  
         [0030]    Stop blocks  120 ,  122  as shown in FIG. 9 have a generally rectangular body portion  124 ,  125  slanted inward to an inward corner at the forward end. A projecting end portion  128 ,  129  of one half the thickness of the block is provided at the bottom side of the block in order to intermesh with corner notches  100   a  and  100   b  so as to secure bar  78  from being sprung downward past a stop block upon occurrence of jackknifing. Corners indicated at  132  are preferably rounded off to facilitate deployment. Connection of the blocks to the wear plate may take the form of bolts (not shown) inserted in holes  134 ,  135 . It is noted that blocks  120  and  122  are each designed for placement on a specific side of the trailer, here the blocks being mirror images of one another.  
         [0031]    Components underneath the trailer are located and sized as follows blocks  120  and  122  are spaced  20  inches from the kingpin. The blocks each have a thickness of 3 inches, an overall length of 21 inches and a width of 7 inches. Projecting end portions  128 ,  129  have a thickness of 2 inches and a width of 4 inches. The blocks are installed parallel to sides of plate  114 , and contacting surfaces of ends of the blocks have an angle of 36 degrees with respect to the center line of the kingpin so as to come into flush contact with the bar upon deployment.  
         [0032]    The system described above may be controlled by use of sensors, switching devices and electronic components as described in applicant&#39;s prior patent, referenced above. In particular, deployment and retraction of the retaining activation bar, carried out by turning the compressed air supply off and on, may be coupled to a speed-responsive signal generator so that the air may be turned on and off at predetermined speeds. This feature, for disabling of the system at a selected low speed such as 15 miles per hour is provided to enable the truck to make sharp turns when needed as in certain city traffic. In addition the control system may include a memory device which records time and date information in conjunction with deployment and retraction of bar, this providing an accurate record of jackknifing events.  
         [0033]    While the invention is described above in terms of specific embodiments, it is not to be understood as limited thereto but is limited only as indicated by the following clams.