Abstract:
A wheel chock is provided with an upstanding handle to assist in moving the wheel chock into and out of operative engagement with a wheel. First and second photo sensor assemblies are mounted in the wheel chock and the handle, respectively, for sensing the presence of a wheel in close proximity to the wheel chock. A signal light assembly is mounted adjacent a loading dock and is operatively connected to the photo sensor assemblies for indicating whether or not a wheel chock is disposed is blocking relation to a wheel and to indicate when the wheel chock is not connected to source of power.

Description:
BACKGROUND OF THE INVENTION 
     The present invention is directed to a wheel chock having a vertically extending handle secured to the base of the wheel chock to assist in the insertion and removal of the wheel chock relative to a tire and photosensing means associated with the handle and the wheel chock for detecting whether or not the wheel chock is in locking relation to a wheel. 
     The use of wheel chocks for blocking movement of a wheel on a vehicle is old and well known in the art. A conventional wheel chock has a substantially triangular cross-sectional configuration with one of the surfaces extending upwardly from the base having a curvature complementary to the wheel curvature. 
     The U.S. patent to Rennick (U.S. Pat. No. 4,122,629) discloses such a wheel chock used to maintain a truck or a trailer portion thereof in proximate location to a loading dock for loading and unloading thereof. The wheel chock is provided with a wheel operated switch which controls the movement of a gate to raise the gate from a blocking position to a non-blocking position when the wheel chock is in a proper blocking position. Rennick discloses that the switch may be operated by means of a pivoted flap or may be an optical-electrical device employing a photocell or the like for sensing the truck&#39;s presence. 
     U.S. Pat. Nos. 2,496,499, 2,720,285, 5,685,397 and 5,913,389 disclose wheel chocks having various types of handle structures connected thereto. However, none of the handle structures have the shape or orientation relative to the wheel chock as disclosed by the handle structure of the present invention. Furthermore, none of these references disclose the use of any electrical switches or photocells used in conjunction with the handles or the wheel chocks. 
     SUMMARY OF THE INVENTION 
     The present invention provides a new and improved wheel chock assembly having a handle assembly significantly different from the handle structures of the prior art as well as new and improved sensing means associated with the wheel chock per se and the handle structure per se for sensing the presence of a wheel relative to the wheel chock to provide a redundant sensing arrangement not disclosed or suggested by the prior art. 
     The above and other objects, features and advantages of the present invention will be more apparent and more readily appreciated from the following detailed description of preferred exemplary embodiment of the present invention, taken in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of a wheel chock assembly and the relationship of the photocell assemblies on the wheel chock and the handle relative to a wheel. 
     FIG. 2 is a top plan view of the wheel chock assembly as shown in FIG. 1 showing the relationship of the photocell assembly on the handle relative to a tire (shown in phantom lines) when the wheel chock assembly is in wheel blocking relation relative to the tire. 
     FIG. 3 is a front elevational view of the wheel chock assembly showing the orientation of the handle photocell assembly relative to the wheel chock. 
     FIG. 4 is a front elevational view of the wheel engaging surface of the wheel chock showing the photocell as it appears through an aperture in the wheel chock. 
     FIG. 5 is a side elevational view of the wheel chock taken in section to show the mounting of the photocell assembly within the wheel chock. 
     FIG. 6 is a sectional view taken along the line  6 — 6  in FIG.  5 . 
     FIG. 7 is a front elevational view of the wheel chock assembly according to the present invention connected to a loading dock by means of a strap and the wiring connection from the wheel chock to a signal light assembly disposed within a building. 
     FIG. 8 is a view of the strap and associated wiring segment and the connectors at opposite ends of the strap. 
     FIG. 9 is a sectional view taken along the line  9 — 9  in FIG.  8 . 
     FIG. 10 is a schematic circuit diagram for the operation of the electrical system associated with the wheel chock assembly. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1-3 show the general relationship of a wheel chock relative to a wheel and more specifically the orientation of the photocells carried by the wheel chock and the wheel chock handle for sensing the presence of the wheel when the wheel chock is in a wheel blocking position. 
     The wheel chock  10  has a substantially triangular cross-sectional configuration with a curved tire engaging surface  12  having a radius of curvature substantially equal to the radius of curvature of a relatively large truck wheel. A first photocell assembly  14  is mounted within the wheel chock  10  in alignment with an aperture  16  located in the curved surface  12  of the wheel chock  10 . 
     The wheel chock  10  is provided with a handle  18  having a vertical portion  20  and a horizontal portion  22 . The horizontal portion  22  is secured in a complementary groove in the bottom surface of the wheel chock  10 . The wheel chock is provided with a handle portion  24  disposed perpendicular to the side wall of the wheel chock  10 . The handle structure  18  facilitates the placement and removal of the wheel chock into and out of wheel blocking relation with a truck tire. The vertical portion  20  of the handle  18  is provided with a built-in photocell assembly  26 . 
     The orientation of the photocell assemblies  14  and  26 , relative to the wheel  15  is best shown in FIGS. 1 and 2. The light emanating and returning to the photocell assembly  14  is disposed substantially perpendicular to the surface  12  of the wheel chock  10  since the tread of the tire will be disposed in direct overlapping relation with respect to the surface  12  as best seen in FIG.  2 . Since the vertically extending portion  20  of the handle  18  is laterally offset from the side wall of the wheel  15 , as best seen in FIG. 2, it is necessary to angle the photocell assembly  26  to be certain that the light rays emanating from the photocell assembly will definitely engage the side wall of a tire mounted on the wheel  15 . Thus, the angle of the light beam from the photocell assembly  26  relative to the plane of the handle  24  would be approximately 30 degrees, as shown in FIG.  2 . 
     Since the wheel chock  10  is mounted on the ground, the aperture  16  is susceptible of having foreign particles of dirt or stone entering the aperture whereby the photocell assembly would be blocked and rendered inoperative. In order to reduce the likelihood of having the transmitting and receiving lenses of the photocell assembly being blocked simultaneously by a single piece of debris, a vertically disposed divider  28  is located in front of the photocell assembly  26  between the transmitting and receiving lenses. 
     The wheel chock  10  has a substantially hollow interior with the exception of a reinforcement member  30  and the photocell assembly  14  is mounted on a bracket  32  secured to the interior surface of the wheel chock  10  by means of screws  34 . The divider plate  28  is also mounted on the bracket  32  so that the divider plate  28  will be disposed between the transmitting lens  36  and the receiving lens  38 , as best seen in FIG.  6 . 
     In order to transmit signals from the photocell assemblies  14  and  26  to a suitable warning light assembly on a loading dock and to assure the presence of the wheel chock in the vicinity of the loading dock for use when a truck is backed into position adjacent the loading dock, the wheel chock  10  is connected to the loading dock  40  by means of a flexible strap  42 , as shown in FIGS. 7-9 inclusive. The strap may be comprised of any suitable material but a two-ply woven fabric of high strength has proven to be the best material. The two plies of the strap  42  are connected together by means of stitches, rivets or any other suitable means along the opposite edges with the center portions of the two strips of fabric being unattached, as best seen in FIG.  9 . Therefore, the cable  44  which contains the wiring for the photocell assemblies, can extend substantially along the entire length of the strap  42  so that the cable  44  will be protected against any damage. The opposite ends of the cable extend outwardly through grommets  46  and the cable is provided with suitable connectors  48  at opposite ends thereof, as shown in FIG. 8. A pair of triangular connectors  50  are secured to opposite ends of the strap  42  by any suitable means. Preferably, the connectors are sewn between the two plies of the fabric strap  42 . The connector  50  at one end of the strap  42  is secured to the wheel chock  10  as shown in FIG.  7  and the corresponding connector  48  of the cable would be connected to a complementary connector (not shown) which in turn is connected to the two photocell assemblies  14  and  26 . The other connector  50  is connected to a bracket  52  which is secured to the face of the loading dock  40  by means of a bolt  54  or the like. The connector  48  is connected to a complementary connector  56  on the end of a cable  58  extending upwardly from the loading dock through the wall of the building to a signal light box  60  secured on an interior surface of the wall  62 . The signal light box is provided with three lights. The upper light  64  is a red light which, when lit, indicates that the wheel chock is not in wheel blocking relation with a truck wheel. The middle light  66  is a green light which, when lit, indicates that a wheel chock  10  is located in wheel blocking relationship with a truck tire and that it is safe to begin loading and unloading operations. The bottom light  68  is a clear light which, when lit, indicates that the wheel block system is not properly connected and is not functional and ready for use. If for any reason the system is damaged such as a broken cable or the like, the light  68  would be on indicating that the wheel chock is not even available for use at the loading dock. 
     With respect to the functional aspects of the wheel chock, the photocell assemblies and the signal lights, attention is directed to the circuit diagram of FIG.  10 . When the wiring connections from the power source  70  to the photo sensor assemblies  14  and  28  are complete and the cable  44  is not damaged in any way, the relay R 1  will be energized to move the switch  72  from the contact  74  to the contact  76  thereby interrupting the current to the light  68  so that the light  68  will not be lit. If any of the connections are broken or the cable damaged, for any reason, the relay R 1  will be de-energized, thereby moving the switch  72  from the contact  76  to the contact  74  so that the light  68  will be lit. This will be indicative of the fact that there is no wheel chock available and that the system should be checked. 
     If the wheel chock  10  is not in wheel blocking relation to a truck wheel, the relay R 2  will remain de-energized and the switch  78  will remain in the position shown in FIG. 10 so that no current will reach the relay R 3 . Since the relay R 3  is de-energized, the switch  80  associated therewith will remain in the position shown in FIG. 10 whereby power will be supplied to the signal light  64  which is a red light warning dock personnel that no loading or unloading operation should be undertaken. 
     When the wheel chock  10  is in the proper wheel locking position, both of the photo sensor assemblies  14  and  26  will provide output signals. The output signal from the photo sensor assembly  26  will energize the relay R 2  thereby moving the switch  78  from the contact  82  to the contact  84  so that power will be supplied from the output of the photo sensor assembly  14  through the switch  78  to energize the relay R 3 . Upon energization of the relay R 3 , the switch  80  will move from the contact  86  to the contact  88  thereby completing the circuit to the light  66 , which is a green light indicative of the fact that loading and unloading operations can take place. 
     The provision of the photo sensor assembly  26  in the handle provides a redundancy check to be certain that the wheel chock is in proper blocking condition with respect to a truck wheel. The three light signal system provides full information to all dock personnel as to the status of the wheel chock and its relation with respect to a truck wheel. Thus, the entire system provides an enhanced safeguard for all dock personnel. 
     While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.