Patent Publication Number: US-2023150319-A1

Title: Hitch for a Material Handling Vehicle

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 17/132,529, filed on Dec. 23, 2020, which is based on and claims priority to U.S. Provisional Patent Application No. 62/952,868, filed on Dec. 23, 2019. Each of the foregoing patent applications is incorporated herein by reference in its entirety. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not Applicable. 
     BACKGROUND 
     Conventional hitch systems typically require manual operation to engage and attach a hitch to a tow bar of a cart or trailer carrying a load. 
     BRIEF SUMMARY 
     In one aspect, the present disclosure provides a hitch configured to selectively latch to a tow bar. The hitch includes a housing defining a central cavity, a frame defining a receiving cavity, a first aperture, and a second aperture, a moveable arm retained within the first aperture, and an actuator. The actuator is configured to move the arm between an unlatched position and a latched position, wherein in the unlatched position, the moveable arm is only retained within the first aperture, and in the latched position, the moveable arm is retained within both the first aperture and the second aperture. The actuator is activated by a sensor that is provided to sense the presence of the tow bar within the receiving cavity, and a position of the sensor is adjustable to accommodate a variety of tow bar geometries. 
     In one aspect, the present disclosure provides a hitch that includes a housing, a frame defining a receiving cavity, a moveable arm, an actuator configured to move the arm between an unlatched position and a latched position, and a contact sensor mounted within the housing on a slotted mounting plate. The arm is configured to engage the tow bar when in the latched position. The slotted mounting plate is configured to enable a position of the contact sensor to be adjusted based on a geometry of the tow bar. The actuator is activated by the contact sensor sensing the presence of the tow bar within the receiving cavity. 
     In one aspect, the present disclosure provides a method of selectively latching a hitch to a tow bar. The method includes detecting, by a sensor, a presence of a tow bar within a receiving cavity of a frame, the frame defining a first aperture and a second aperture, and moving, by an actuator, an arm between an unlatched position and a latched position. The arm is configured to be retained within the first aperture in response to the detected presence of the tow bar. In the unlatched position, the method further includes retaining the arm only within the first aperture, and, in the latched position, retaining the arm within both the first aperture and the second aperture. A position of the sensor is adjustable to accommodate a variety of tow bar geometries. 
     In one aspect, the present disclosure provides a method of selectively latching a hitch to a tow bar. The method includes detecting, by an optical sensor coupled to an inner surface of one or more hitch plates of a frame, a presence of a tow bar within a receiving cavity of the frame, the tow bar defining an aperture. The method further engaging an arm with the tow bar, moving the arm between an unlatched position and a latched position in response to the engagement of the tow bar with the arm, the arm configured to be retained within the aperture in the latched position. The optical sensor emits a field of view in a direction towards the tow bar, and the frame includes at least two guide plates that are adjustable to accommodate a variety of tow bar geometries. 
     In one aspect, the present disclosure provides a method of selectively latching a hitch to a tow bar. The method includes detecting, by a sensor, a presence of a tow bar within a receiving cavity of a frame, the tow bar defining an aperture, engaging an arm with the tow bar, and moving the arm from an unlatched position to a latched position in response to the engagement of the tow bar with the arm, the arm configured to be retained within the aperture in the latched position. The frame includes at least two guide plates at least two guide plates disposed on opposite sides of the frame, and the at least two guide plates are adjustable to accommodate a variety of tow bar geometries. 
     The foregoing and other aspects and advantages of the disclosure will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration a preferred configuration of the disclosure. Such configuration does not necessarily represent the full scope of the disclosure, however, and reference is made therefore to the claims and herein for interpreting the scope of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The invention will be better understood and features, aspects and advantages other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such detailed description makes reference to the following drawings. 
         FIG.  1    is a schematic of a system that detects and engages a hitch and confirms engagement of the hitch according to aspects of the present disclosure; 
         FIG.  2    is an isometric view of a hitch according to aspects of the present disclosure; 
         FIG.  3    is an exploded isometric view of the hitch of  FIG.  2    with a sensing mechanism; 
         FIG.  4    is a side isometric view of the hitch and the sensing mechanism of  FIG.  3    in an unengaged state; 
         FIG.  5    is a side isometric view of the hitch and the sensing mechanism of  FIG.  3    in an engaged state; 
         FIG.  6    is a side elevational view of the hitch and the sensing mechanism of  FIG.  3    in the unengaged state; 
         FIG.  7    is a rear isometric view of the hitch of  FIG.  2    in an unlatched position; 
         FIG.  8    is a partial bottom isometric view of the hitch of  FIG.  2    in a latched position; 
         FIG.  9    is an exploded isometric view of the hitch of  FIG.  2    with lead-in plates; 
         FIG.  10    is a top plan view of the hitch of  FIG.  9    with a tow bar; 
         FIG.  11    is a flow chart illustrating steps in a method for adjusting the sensing mechanism of  FIG.  3   ; 
         FIG.  12    is a flow chart illustrating steps for detecting and confirming engagement of the hitch of  FIG.  2    with a tow bar; 
         FIG.  13    is a top plan view of the hitch of  FIG.  2    with lead-in plates according to another aspect of the present disclosure; 
         FIG.  14    is a top plan view of the hitch of  FIG.  2    with lead-in plates according to yet another aspect of the present disclosure; 
         FIG.  15    is a top plan view of the hitch of  FIG.  2    with lead-in plates according to still another aspect of the present disclosure; 
         FIG.  16    is a side isometric view of the hitch of  FIG.  2    with lead-in plates according to another aspect of the present disclosure; 
         FIG.  17    is a side isometric view of the hitch of  FIG.  2    with lead-in plates according to yet another aspect of the present disclosure; 
         FIG.  18    is a top plan view of the hitch of  FIG.  2    having a contact plate integrally formed with lead-in plates according to an aspect of the present disclosure; 
         FIG.  19    is a top plan view of a hitch according to another aspect of the present disclosure; 
         FIG.  20    is a top plan view of a hitch according to another aspect of the present disclosure; 
         FIG.  21    is a top plan view of a hitch according to another aspect of the present disclosure; 
         FIG.  22    is a top plan view of a hitch according to another aspect of the present disclosure; 
         FIG.  23    is a top plan view of a hitch according to another aspect of the present disclosure; 
         FIG.  24    is an isometric view of a hitch according to another aspect of the present disclosure; 
         FIG.  25    is a top view of the hitch of  FIG.  24   ; 
         FIG.  26    is a cross-sectional view of the hitch of  FIG.  25    taken along line  26 - 26 ; 
         FIG.  27    is a side isometric view of the hitch of  FIG.  24    with components hidden and a hook plate being transparent; 
         FIG.  28    is a side view of the hitch of  FIG.  24    with the hitch partially receiving a tow ring; and 
         FIG.  29    is a side isometric view of the hitch of  FIG.  28    with the hitch fully latched to the tow ring. 
     
    
    
     DETAILED DESCRIPTION 
     Before any aspect of the present disclosure are explained in detail, it is to be understood that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The present disclosure is capable of other configurations and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
     The following discussion is presented to enable a person skilled in the art to make and use aspects of the present disclosure. Various modifications to the illustrated configurations will be readily apparent to those skilled in the art, and the generic principles herein can be applied to other configurations and applications without departing from aspects of the present disclosure. Thus, aspects of the present disclosure are not intended to be limited to configurations shown, but are to be accorded the widest scope consistent with the principles and features disclosed herein. The following detailed description is to be read with reference to the figures, in which like elements in different figures have like reference numerals. The figures, which are not necessarily to scale, depict selected configurations and are not intended to limit the scope of the present disclosure. Skilled artisans will recognize the non-limiting examples provided herein have many useful alternatives and fall within the scope of the present disclosure. 
     It should be appreciated that vehicles, such as trucks, commonly pull carts or trailers carry a load for many applications. It will be apparent to those of skill in the art that the present disclosure may be provided in various types of material handling vehicle configurations, including, for example, reach vehicles, SWING REACH® vehicles, pallet trucks, order pickers, narrow-aisle turret trucks, and any other material handling vehicle. 
     Conventional hitch systems may require manual operation to engage a hitch or attach the hitch to a tow bar of a load. In some instances, conventional hitch systems may require a truck operator or user to visually detect the presence of a tow bar in the hitch. After manual detection of the tow bar, the hitch may be manually engaged or automatically engaged using a spring mechanism. Consequently, conventional hitch systems are compatible with limited tow bar geometries. Further, conventional hitch systems still require manual operations. 
     In many applications, it may be useful to have an automatic hitch to simplify and shorten the engagement process. Some conventional hitch systems use proximity sensors to detect the presence of a tow bar of a specific geometry designed to fit within the hitch. However, these conventional hitch systems still require manual operation to activate the hitch and engage the tow bar. Further, the sensors and/or geometry of the hitch limit tow bar compatibility. Therefore, a need exists for an automatic hitch that can detect the presence of a tow bar and is compatible with a variety of tow bar shapes and sizes. 
     Referring to  FIG.  1   , the present disclosure generally provides an automatic hitch that may automatically engage a hitch according to a method  50 . In some aspects, the method  50  may include detecting the presence of a tow bar, at step  52 , in a receiving cavity of the hitch. Further, the method  50  may include automatically engaging the hitch at step  54 . For example, the method  50  may include actuating a moveable arm to secure the tow bar of a cart to the hitch, which will be described in greater detail below. In this way, for example, the process of securing the tow bar to the hitch may be shortened and simplified. Once secured, the method  50  may also include confirming engagement with additional sensors at step  56 . More specifically, if sensors detect that a moveable arm is not latched or a tow bar is not engaged, the method  50  may include providing indication to a truck operator or supervisor and/or preventing forward motion of the truck. 
       FIG.  2    illustrates a hitch  100  according to a non-limiting example of the present disclosure. The hitch  100  may include a main body  102  comprising a housing  104  and a frame  106 . The frame  106  comprises a first surface  108 , a second surface  110  spaced from and substantially parallel to the first surface  108 , and a third surface  112  extending between and substantially perpendicular to the first and second surfaces  108 ,  110 , thereby defining a receiving cavity  114 . The first surface  108  and the second surface  110  define a first aperture  116  and a second aperture  118 , respectively. In the illustrated example, the hitch  100  is a pin and clevis style hitch. More specifically, a pin  120  may be removably retained within the first aperture  116  and the second aperture  118 . Further, the pin  120  may be configured to move between a latched position and an unlatched position (see, e.g.,  FIG.  7   ) by a linear actuator  122  disposed in a central cavity  124  of the housing  104 . The second aperture  118  thus is configured to receive the pin  120  when in the latched position. Although  FIG.  2    illustrates a pin and clevis style hitch that uses a linear actuator, the present disclosure may be particularly useful for other hitch styles as well. Particularly, the present disclosure may use a hitch including a moveable arm that is configured to be moved by a linear actuator, a servomotor, or the like to engage a tow bar. According to a non-limiting example, the moveable arm may be a hook that is rotatably received by apertures defined by a main body of the hitch. Alternatively, a hitch according to the present disclosure may comprise a ring or a bar that is configured to receive, mate with, or engage a moveable pin, latch, or a hook. 
     Turning to  FIG.  3   , referring to the illustrated non-limiting example, the third surface  112  includes a plurality of receiving apertures  126 . In the present aspect, the third surface  112  is substantially rectangular in shape and includes four receiving apertures  126  that are positioned near each corner thereof, however, alternative configurations may include more or fewer receiving apertures  126  in a variety of arrangements. A flanged bushing  128  is provided in each of the receiving apertures  126  and is configured to receive and retain components of a sensing mechanism  130  that are provided to sense the presence of a tow bar. For example, the sensing mechanism  130  may include compression springs  132 , standoffs  134 , through bolts  136 , lock nuts  138 , and a contact plate  140 , and may be configured to trigger a contact sensor  144 . The contact plate  140  may include a plurality of securing apertures  146  that are positioned to correspond to each of the receiving apertures  126  of the third surface  112 . Similarly, the sensing mechanism  130  may use an equal number of the compression springs  132 , the standoffs  134 , the through bolts  136 , and the lock nuts  138  to correspond to each receiving aperture  126  and securing aperture  146 . 
     Turning to  FIG.  4   , each of the through bolts  136  may be received by one of the securing apertures  146  of the contact plate  140 . Each of the compression springs  132  may be arranged on one of the standoffs  134 , which may be held by one of the through bolts  136 . The through bolts  136  are further retained by the receiving apertures  126  of the third surface  112 , and secured by the lock nuts  138  (see, e.g.,  FIG.  6   ). The flanged bushing  128  may be sized to have a diameter smaller than a diameter of the compression spring  132  but greater than a diameter of the standoff  134 . Thus, the standoff  134  may be slidably retained within the receiving aperture  126  and flanged bushing  128 , whereas an end of the compression spring  132  may abut the flanged bushing  128 . Consequently, when (or as) the standoffs  134  slide through the receiving apertures  126 , the compression springs  132  compress and extend accordingly. 
     Still referring to  FIG.  4   , because the compression springs  132  are disposed between the contact plate  140  and the third surface  112 , the contact plate  140  is biased away from the third surface  112 . However, turning to  FIG.  5   , the contact plate  140  may be forced toward the third surface  112  by a force, shown by arrow  148 . More specifically, when force  148  is applied (e.g., by a tow bar), the standoffs  134  may slide through the flanged bushings  128 , and the compression springs  132  may compress, thereby allowing the contact plate  140  to move toward the third surface  112 . When (or as) the standoffs  134  and through bolts  136  slide through the third surface  112 , they may trigger the contact sensor  144 , which may activate the linear actuator  122 . Although the hitch  100  according to the present aspect uses compression springs  132  to position the contact plate  140  relative to the third surface  112 , any type of spring/damper system may be used, such as a hydraulically pressurized system, air pressurized system, alternative spring types, or elastic materials, such as rubber. 
     Turning to  FIG.  6   , the contact sensor  144  may be held within the central cavity  124  of the housing  104  by a slotted mounting plate  150 . The slotted mounting plate  150  is provided to allow for the hitch  100  to be adjusted to accommodate a variety of tow bar sizes and shaped. That is, the contact sensor  144  may be secured with fasteners at any point along a length of a slot  152  to be compatible with various tow bar sizes. For example, smaller tow bars would require the contact sensor  144  to be position closer to the third surface  112  than larger tow bars. 
     As mentioned above, referring to  FIG.  7   , movement of the pin  120  is controlled by a linear actuator  122 . Although a linear actuator is used in the present example, alternative non-limiting examples may use other types of actuators, such as, for example, a motor and a pulley, springs, or the like. A flag plate  154  may be provided adjacent the linear actuator  122  so that it moves in conjunction with the linear actuator  122 . Further, a pin raised sensor  156  may be disposed within the central cavity  124  of the housing  104  to sense when the pin  120  is in the unlatched position. More specifically, the flag plate  154  may trigger the pin raised sensor  156  when the pin is completely raised, which would indicate that the pin  120  is in the unlatched position. Similarly, turning to  FIG.  8   , a pin lowered sensor  158  may be provided adjacent the second aperture  118  to sense when the pin  120  is in the latched position. More specifically, when the pin is inserted in and extends through the second aperture  118 , it may obstruct the pin lowered sensor  158 , which indicates the latched position. Each of the aforementioned sensors may be a proximity sensor, laser scanner, pressure sensor, mechanical switch, or another type of sensor. 
     Turning to  FIG.  9   , the hitch  100  may further include optional lead-in plates  160  to guide and center a tow bar. In the illustrated non-limiting example, two lead-in plates  160  are provided on opposing sides of the main body  102  and oriented so that they are symmetrical about the pin  120 . However, one of ordinary skill in the art would recognize that any number of lead-in plates may be used. Each of the lead-in plates  160  include an attachment surface  162  with a plurality of apertures  164  that is secured to the main body  102  using screws  166 , however other methods may be used, such as adhesive, nuts and bolts, clamps, or they may be integrally formed with the main body  102 . Further, any number of apertures  164  and accompanying screws  166  may be used, such as, for example, two, three, four, six, etc. As best seen in  FIG.  10   , a guide surface  168  may extend from the attachment surface  162  at an angle α. In some instances, the angle α may be between 30 degrees and 60 degrees. Further, the angle α may be between 40 degree and 50 degrees. 
     Generally, the sensing mechanism  130  is provided so that it may detect the presence of a tow bar. The tow bar may be a tow bar of a trailer, cart, or the like.  FIG.  10    illustrates a tow bar or a tow hitch  172  having a central opening  174  positioned within the receiving cavity  114 . If applicable, the lead-in plates  160  would encourage and guide the tow bar  172  toward center alignment in the receiving cavity  114 . When (or as) the tow bar  172  is positioned in the receiving cavity  114 , it may contact and forcibly depress the sensing mechanism  130 . More specifically, the tow bar  172  may contact the contact plate  140 , apply the force  148  to the contact plate  140 , which may slide the standoffs  134  and through bolts  136  through the receiving apertures  126  of the third surface  112 , thereby triggering the contact sensor  144 . Once the contact sensor  144  senses the presence of the tow bar  172 , it may activate the linear actuator  122 , which may move the pin from the unlatched position to the latched position. The pin  120  may remain latched until it is manually deactivated. That is, in order to move the pin  120  from the latched position, a button, switch, lever, or the like may be manually triggered to initiate movement of the pin from the latched position to the unlatched position. Additionally or alternatively, an automated system may be used that is configured to release the pin  120  at a particular time or at a designated location. 
       FIG.  11    illustrates a method  200  for installing/adjusting the sensing mechanism to the hitch  100  according to aspects of the present disclosure. As mentioned above, the hitch may be installed and adjusted to accommodate a tow bar having a particular shape and size. For example, the pin may be moved to the unlatched position at step  202 , and a tow bar may be manually positioned in the receiving cavity so that it is aligned with and may be engaged by the pin at step  204 . When in this position, the contact sensor may be manually adjusted so that it will be triggered by the sensing mechanism when the tow bar is positioned in the receiving cavity at step  206 . More specifically, mentioned above referring to  FIG.  6   , the contact sensor  144  may be adjusted and secured with fasteners along a length of the slot  152  to be compatible with various tow bar sizes. 
     Turning to  FIG.  12   , the hitch system according to aspects of the present disclosure may also provide a check system  210  to ensure a load is engaged by the hitch. For example, if the pin raised sensor is activated ( 212 ), the load is not secured, and indication may be provided to a truck operator or supervisor ( 214 ). However, if the pin raised sensor is not activated ( 216 ), and if the pin lowered sensor and the contact sensor are both activated ( 218 ,  220 ), then the tow bar is engaged ( 222 ), and the hitch may move the load. However, if the contact sensor is not activated ( 224 ), but the lowered sensor is activated ( 226 ), the truck knows the tow bar is not engaged ( 228 ). This scenario may provide indication to a truck operator or supervisor, such as, for example, an audio and/or visual alarm. Similarly, if the contact sensor is activated ( 218 ), but the lowered sensor is not activated ( 230 ), the pin has not fully engaged the tow bar ( 232 ). This scenario may also provide indication to a truck operator or supervisor. 
       FIGS.  13 ,  14 , and  15    illustrate the hitch  100  with alternative lead-in plates  360 ,  460 ,  560 , respectively. Referring to  FIG.  13   , each lead-in plate  360  may include an attachment surface  362  secured to the body  102  and a guide surface  368  extending from the attachment surface  362  at an angle β. The angle β may be tuned to meet design requirements or customer preferences. For example, referring to  FIG.  13   , the angle β may be less than 45 degrees. Further, the angle β may be between 20 and 40 degrees. Referring to  FIG.  14   , the lead-in plates  460  each may include an attachment surface  462  secured to the body and a guide surface  468  extending from the attachment surface  462  at an angle γ. The angle γ may be between 40 and 50 degrees. Support ribs  496  may be disposed between the attachment surfaces  462  and the guide surfaces  468 . Similarly, referring now to  FIG.  15   , the lead-in plates  560  may include an attachment surface  562  secured to the body  102  and a guide surface  568  extending from the attachment surface  562  at an angle δ. The angle δ may be greater than 45 degrees. For example, the angle δ may be between 50 and 70 degrees. Support ribs  596  may be disposed between the attachment surfaces  562  and the guide surfaces  568 . 
     Alternatively or additionally, any of the aforementioned the lead-in plates may include slots to slidably retain portions of the contact plate. For example, referring to  FIG.  16   , the hitch  100  may include lead-in plates  660  having slots  676  that are configured to slidably retain and guide extensions  678  of a contact plate  640 . Similarly, referring to  FIG.  17   , the hitch  100  may include lead-in plates  760  having the slots  776  that are configured to slidably retain and guide fasteners  780  that are attached to the contact plate  740 . More specifically, the contact plate  740  may include extensions  778  extending substantially perpendicularly therefrom. The fasteners  780  may be secured to the extensions  778  so that they extend through the slots  776  and slide therealong as the contact plate  740  moves. 
     Turning to  FIG.  18   , the hitch  100  may not have distinct lean-in plates like the lead-in plates  160  shown in  FIG.  9   . Alternatively, the hitch  100  may include lead-in plates  860  integrally formed with a contact plate  840 . The lead-in plates  860  and contact plate  840  are similar to the lead-in plates  160  and contact plate  140  of  FIG.  9   . However, the lead-in plates  860  include an attachment surface  862  that is integrally formed with the contact plate  140 . A guide surface  868  is integrally formed with and extends from the attachment surface  862  at an angle ε. Similar to the angles β, γ, and δ above, the angle ε may be increased or decreased to meet design requirement or customer preferences. 
       FIG.  19    illustrates another non-limiting example of a hitch  900  according to the present disclosure. The hitch  900  may be similar in design and functionality to the hitch  100 , with similar elements identified using like reference numerals, except as described herein to as apparent from the figures. The hitch  900  may include a contact plate  940  having angled surfaces  982   a  symmetrical about the pin  120  and flat surface  982   b . The angled surfaces  982   a  of the contact plate  940  may be angled at varying degrees to meet particular design requirements or customer preferences. Further, unlike the contact plate  140 , the contact plate  940  may include two extensions  984  that are slidably retained by two receiving apertures  926  in the third surface  112  and configured to guide the contact plate  940  toward the third surface  112  during compression of a centrally located spring  986  disposed thereon. These extensions  984  are symmetrical about the centrally located spring  986  and may be integrally formed with the contact plate  940  or connected thereto by way of known methods, such as adhesive, fasteners, press-fit, or the like. Alternatively, the contact plate  940  may include more or fewer extensions  984 . For example, referring to  FIG.  20   , the contact plate  940  may include only one extension  984 . 
     Still referring to  FIGS.  19  and  20   , the centrally located spring  986  may be a compression spring that is positioned at a first end  988  around a cylindrical extension  990  of the contact plate  940 . A second end  992  of the centrally located spring  986  may abut or be secured to the third surface  112  by way of adhesive, fastener, or the like. The cylindrical extension  990  may be integrally formed with the contact plate  940  or coupled thereto using known methods, such as adhesive, fasteners, press-fit, or the like. 
     Therefore, similar to the hitch  100  of  FIGS.  1 - 10   , the hitch  900  is configured so that the contact plate  940  is biased away from the third surface  112  and may be forcibly pressed toward the third surface  112 . By pressing the contact plate  940  toward the third surface  112 , the centrally located spring  986  compresses, and the at least one extension  984  slides through the at least one securing aperture  946  in the third surface  112  until it triggers the contact sensor  144  (see, e.g.,  FIG.  5   ). 
       FIG.  21    illustrates another non-limiting example of a hitch  1000  according to the present disclosure. The hitch  1000  may be similar in design and functionality to the hitch  100 , with similar elements identified using like reference numerals, except as described herein to as apparent from the figures. The hitch  1000  may include a contact plate  1040  having a contact surface  1042  and two extensions  1084  extending through receiving apertures  1026  in the third surface  112 . A centrally located spring  1086  may be disposed between the two extensions  1084  and the third surface  112  so that it will compress if the contact plate  1040  is pressed into the third surface  112 . The contact surface  1042  may have a width w that is less than a width W of the frame  106 . For example, in the illustrated non-limiting example, the width w is less than 50% of the width W of the frame. The two extensions  1084  extend from the edges  1094  of the contact surface  1042  so that they are symmetrical about the centrally located spring  1086 . 
     Still referring to  FIG.  21   , the hitch  1000  may include two lead-in plates  1060  coupled to the frame  106  so that they are symmetrical about the pin  120 . The lead-in plates  1060  each include an attachment surface  1062  that may be attached to the frame  106  with screws and a guide surface  1068  integrally formed with the attachment surface  1062  at an angle ζ. Although the present non-limiting example shows the angle ζ greater than or equal to 45 degrees, similar to the aforementioned non-limiting examples, the angle ζ can be tuned to meet certain design requirements or customer preferences. 
       FIG.  22    illustrates another non-limiting example of a hitch  1100  according to the present disclosure. The hitch  1100  may be similar in design and functionality to the hitch  100 , with similar elements identified using like reference numerals, except as described herein to as apparent from the figures. The hitch  1100  may include a contact plate  1140  having a contact surface  1142  and two extensions  1184  extending through receiving apertures  1126  in the third surface  112 . A centrally located spring  1186  may be disposed between the two extensions  1184  and the third surface  112  so that it may compress when (or as) the contact plate  1140  is pressed into the third surface  112 . In the illustrated non-limiting example, the contact surface  1142  has a width w′ that is less than the width W of the frame  106 , but greater than 50% the width W. The two extensions  1184  extend from the contact surface  1142  so that they are symmetrical about and adjacent the centrally located spring  1186 . 
     Still referring to  FIG.  22   , the hitch  1100  may include two lead-in plates  1160  coupled to the frame  106  so that they are symmetrical about the pin  120 . The lead-in plates  1160  each may include an attachment surface  1162  that is attached to the frame  106  with screws  1166 . Further, the lead-in plates  1160  each may include a guide surface  1168  integrally formed with and extending from the attachment surface  1162  at an angle η. Although the present non-limiting example shows the angle η less than or equal to 45 degrees, similar to the above non-limiting examples, the angle η may be tuned to meet certain design requirements or customer preferences. 
       FIG.  23    illustrates still another non-limiting example of a hitch  1200  according to the present disclosure. The hitch  1200  may be similar in design and functionality to the hitch  100 , with similar elements identified using like reference numerals, except as described herein to as apparent from the figures. The hitch  1200  may include a sensing mechanism  1230  including a contact plate  1240 , standoffs  1234 , through bolts  1236 , lock nuts  1238 . The contact plate  1240  may include a plurality of securing apertures  1246  that are positioned to correspond to receiving apertures  1226  of the third surface  112 . Similarly, the sensing mechanism  1230  may use an equal number of the standoffs  1234 , the through bolts  1236 , and the lock nuts  1238  to correspond to each receiving aperture  1226  and securing aperture  1246 . Each of the through bolts  1236  may be received by one of the securing apertures  1246  of the contact plate  1240 . Each of the standoffs  1234  may be held by one of the through bolts  1236 . The through bolts  1236  are further retained by receiving apertures  1226  of the third surface  112  and flanged bushings  1228  and secured by the lock nuts  1238 . A centrally located spring  1286  is disposed between the two standoffs  1234 , and between the third surface  112  and the contact plate  1240  so that it will compress when (or as) the contact plate  1240  is pressed into the third surface  112 . 
     Still referring to  FIG.  23   , the hitch  1200  may include two lead-in plates  1260  coupled to the frame  106  so that they are symmetrical about the pin  120 . The lead-in plates  1260  each may include an attachment surface  1262  that attaches to the frame  106  with screws  1266 . Further, the lead-in plates  1260  each may include a guide surface  1268  integrally formed with and extending from the attachment surface at an angle θ. Although the present non-limiting example shows the angle θ between 30 and 60 degrees, again, similar to the above non-limiting examples, the angle θ may be tuned to meet certain design requirements or customer preferences. In the non-limiting example illustrated, the guide surfaces  1268  further include support ribs  1296  disposed between the guide surfaces  1268  and the attachment surfaces  1262 . 
     As described herein the hitch system may be designed to include different style hitch mechanisms and different hitching operations. For example, a hitch according to the present disclosure may include a hook plate or latch that is configured to pivotally receive a tow ring upon insertion of the tow ring into the hitch. In some non-limiting examples, the hitch with a hook plate may operate in a passive manner, rather than an active or automatic manner, and the tow ring may be mechanically latched upon insertion into the hitch. The hitch may include sensors to confirm latching and unlatching of the tow ring and to detect the presence or absence of the tow ring within the hitch. These sensors may be utilized to provide a positive indication, for example, to a display or a controller on an autonomous material handling vehicle, that the tow hitch is latched or unlatched. 
       FIGS.  24 - 29    illustrated one non-limiting example of a hitch  1300  that is configured to passively latch to a tow hitch  1302  (see  FIG.  29   ). In the illustrated non-limiting example, the hitch  1300  includes a mounting plate  1304 , an actuator enclosure  1306 , a pulley enclosure  1308 , and a hitch assembly  1310 . The mounting plate  1304  may be attached or coupled to a material handling vehicle (not shown) to couple the hitch  1300  to the material handling vehicle. In general, the hitch  1300  may be coupled to an end of the material handling vehicle. 
     The actuator enclosure  1306  may be coupled to the mounting plate  1304  and may enclose a linear actuator  1312  (see  FIGS.  26  and  27   ). The actuator enclosure  1306  includes a plurality of side plates  1314  that may be coupled to the mounting plate  1304  and a front plate  1316  that is coupled to the plurality of side plates  1314  at an end opposite to the mounting plate  1304 . The pulley enclosure  1308  may be supported by the actuator enclosure  1306  and may at least partially enclose a pulley (not shown) around which an opening cable  1317  is wound. An output shaft  1318  of the linear actuator  1312  may at least partially extend into the pulley enclosure  1308 . The output shaft  1318  may be coupled to an end of the opening cable  1317  to enable the linear actuator  1312  to selectively open the hitch  1300  and unlatch the tow hitch  1302 . 
     The hitch assembly  1310  may include a pair of guide plates  1320 , a pair of hitch plates  1322 , and a hook plate  1324 . The pair of guide plates  1320  may be coupled to the mounting plate  1304  and may be arranged on laterally-opposing sides of the actuator enclosure  1306  and the hitch plates  1322 . Each of the guide plates  1320  may include a guide surface  1326  that are arranged at an angle relative to the hitch plates  1322 . In the illustrated non-limiting example, an acute angle may be formed between the guide surfaces  1326  and the laterally-outer surfaces of the hitch plates  1322 . In this way, for example, the guide surface  1326  may direct the tow hitch  1302  in a direction toward the hook plate  1324  during latching. 
     The hitch plates  1322  may be coupled to and extend from the actuator enclosure  1306 . Each of the hitch plates  1322  may define an open end  1328  from which a hitch slot  1330  extends at least partially through the respective hitch plate  1322 . In the illustrated non-limiting example, the hitch slot  1330  includes a tapered portion  1332  that angles in a direction perpendicular to the guide surfaces  1326  on the guide plates  1320 . The hitch slots  1330  may transition from the tapered portion  1332  to a planar portion  1334  that terminates with a semi-circularly-shaped ending of the hitch slots  1330 . 
     The hook plate  1324  is arranged laterally between the hitch plates  1322  and is pivotally coupled between the hitch plates  1322 . In the illustrated non-limiting example, the hook plate  1324  includes a hook portion  1336  arranged at one end thereof and a pivot portion  1338  arranged at an opposing end thereof. The pivot portion  1338  is coupled to the hitch plates  1322  via a pivot pin  1340  that allows the hook plate  1324 , and specifically the hook portion  1336 , to pivot relative to the hitch plates  1322 . A tab  1342  may extend downwardly (e.g., from the perspective of  FIG.  26   ) from the pivot portion  1338 . The opening cable  1317  may be coupled to the hook plate  1324  at an upper region of the hook portion  1336 . A coil spring  1343  may be biased between one end of the hook plate  1324  and the front plate  1316  of the actuator enclosure  1306 . 
     With specific reference to  FIG.  27   , the hitch  1300  may include a first sensor  1344 , a second sensor  1346 , and a hitch sensor  1348 . The first sensor  1344 , the second sensor  1346 , and the hitch sensor  1348  may be coupled to an inner surface of one of the hitch plates  1322  and may be arranged between the hitch plate  1322  and the hook plate  1324 . The first sensor  1344  and the second sensor  1346  may be proximity sensors that are configured to detect if the sensor is being blocked by a component (e.g., the hook plate  1324 ). The hitch sensor  1348  may be an optical sensor that is configured to detect the presence of the tow hitch  1302 . In the illustrated non-limiting example, the hitch sensor  1348  emits a field of view in a direction toward the hook portion  1336 . 
     Turning to  FIGS.  27 - 29   , in operation, the hitch  1300  may be configured to latch to and unlatch from the tow hitch  1302 . When the tow hitch  1302  is not being inserted into the hitch  1300 , the hook plate  1324  may be in a first position ( FIG.  27   ) where the first sensor  1344  is blocked by the hook plate  1324 . Upon insertion of the tow hitch  1302  into the hitch slot  1330 , the tow hitch  1302  may engage the hook portion  1336  of the hook plate  1324  and cause the hook plate  1324  to pivot to a second position ( FIG.  28   ). In the second position, the first sensor  1344  may be unblocked (i.e., the hook plate  1324  pivots a sufficient distance to not block the first sensor  1344 ). The transition between the first position and the second position may compress the coil spring  1343 , which may provide a force on the hook plate  1324  that biases the hook plate  1324  back toward the first position. 
     As the tow hitch  1302  is continued to be inserted through the hitch slot  1330 , the tow hitch  1302  eventually reaches a position where a ring  1350  defined by the tow hitch  1302  aligns with the hook portion  1336  of the hook plate  1324 . When the ring  1350  is aligned with the hook portion  1336 , the hook plate  1324  pivots back to the first position, via the force from the coil spring  1343  and the hook portion  1336  extends through the ring  1350 , thereby latching the tow hitch  1302  to the hitch  1300  ( FIG.  29   ). The latching of the tow hitch  1302  may be confirmed by the hitch sensor  1348  sensing the presence of the tow hitch  1302 . In some non-limiting examples, the combination of the first sensor  1344  being blocked and the hitch sensor  1348  sensing the presence of the tow hitch  1302  may be used to confirm that the tow hitch  1302  is latched. In some non-limiting examples, the first sensor  1344  transitioning from a blocked state to an unblocked state, and then the hitch sensor  1348  sensing the presence of the tow hitch  1302  may be used to confirm that the tow hitch  1302  is latched. In any case, the sensors on the hitch  1300  may be used to provide a positive indication that the tow hitch  1302  is latched, which may enable an autonomous material handling vehicle to confirm the presence of a tow cart being attached thereto. 
     The tow hitch  1302  may be selectively unlatched from the hitch  1300  via actuation of the linear actuator  1312 . For example, the linear actuator  1312  may be in communication with a controller on a material handling vehicle that controls the actuation of the output shaft  1318 . The output shaft  1318  may be selectively actuated from an extended position to a retracted position, which, in turn, pulls on the opening cable  1317  and the pulley and pivots the hook plate  1324  from the first position to the second position. In the second position, the tow hitch  1302  may be unlatched and removed from the hitch  1300 . 
     Within this specification embodiments have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the invention. For example, it will be appreciated that all preferred features described herein are applicable to all aspects of the invention described herein. 
     Thus, while the invention has been described in connection with particular embodiments and examples, the invention is not necessarily so limited, and that numerous other embodiments, examples, uses, modifications and departures from the embodiments, examples and uses are intended to be encompassed by the claims attached hereto. The entire disclosure of each patent and publication cited herein is incorporated by reference, as if each such patent or publication were individually incorporated by reference herein. 
     Various features and advantages of the invention are set forth in the following claims.