Abstract:
A safety cage improves the safety of workers servicing tanker vehicles having top side hatches. A part or parts of the cage can be repositioned to permit the hatch cover to be opened and then can be returned to a safety enhancing position.

Description:
BACKGROUND OF THE INVENTION 
     Loading tanks of transport trucks is a hazardous and dangerous task. To prepare the tank for loading, it is necessary for a worker to open the hatch or hatches on the upper surface of the tank. The upper surface of the tank is typically cylindrical and often slippery causing frequent slips and falls by workers. Further, the worker must access the top surface again after the tank is loaded to close the hatch or hatches on the tank. Because of these hazardous conditions, it is known in the art to use safety cages to protect the workman, such as the one disclosed in U.S. Pat. No. 7,216,741. 
     Most safety cages in the art are ineffective in providing fall protection for transport trucks such as dry bulk transport trucks. The typical standard operating procedure for loading dry bulk transport trucks is to open the hatch at one location, drive the truck to a loading station for loading, and then close the hatch at the second location or return the truck to the original or another location suitable for closing the hatch. The hatch cover is normally hinged on a horizontal axis extending in the longitudinal direction of the tank and truck. When the hatch cover is opened, it is desirable to pivot the hatch cover to a fully open position in which the top of the cover rests on the upper part of one lateral side of the tank. If the side railing of a safety cage is spaced laterally outward a sufficient distance to permit the hatch cover to be fully opened, the side railing is positioned too far laterally to prevent the worker from falling. It also may be too far away to be used by the worker as a grab bar to regain balance or to stop a fall. Conversely, if the side railing of a safety cage is spaced laterally inward a sufficient distance to prevent the worker from falling, the hatch cover is not permitted to be fully opened. 
     SUMMARY OF THE INVENTION 
     The present invention includes an apparatus for providing safe access to the top of a mobile container having a hatch cover positioned at the top of the mobile container that pivots between an open and a closed position. In one embodiment of the invention, the apparatus includes a gangway capable of being raised and lowered and a cage having a first end attached to the gangway and an opposing second end. The cage may also include a first lateral side, a second lateral side, a joining side for joining the first and second lateral sides at the opposing second end of the cage, and a partial floor adjoining the first and second lateral sides at the first end. The partial floor may pivot about an axis extending parallel with the first end of the cage. Further, the joining side may have a gate that slidably engages the joining side. The gangway or cage is typically attached to a service station platform for preparing the mobile container for loading. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of an access platform, the gangway and the safety cage positioned above the hatch of a dry bulk material tank mounted on a truck; 
         FIG. 2  is a top view of the safety cage and the gangway shown in  FIG. 1 ; 
         FIG. 3A  is a side view of the safety cage and the gangway in the stored position; 
         FIG. 3B  is a perspective view of the safety cage and the gangway in the stored position; 
         FIG. 4A  is a side view of the safety cage and the gangway in the extended loading position; 
         FIG. 4B  is a perspective view of the safety cage and the gangway in the extended loading position; 
         FIG. 4C  is a close-up view from  FIG. 4B  of the roller feature of the safety cage. 
         FIG. 5A  is a side view of the safety cage and the gangway in the extended loading position with the gate raised; 
         FIG. 5B  is a perspective view of the safety cage and the gangway in the extended loading position with the gate raised; 
         FIG. 6A  is a side view of the safety cage and the gangway in the extended loading position with the cage floor pivoted upward; 
         FIG. 6B  is a perspective view of the safety cage and the gangway in the extended loading position with the cage floor pivoted upward; 
         FIG. 7  is a front view of an access platform, the gangway and the safety cage positioned above the hatch of a dry bulk material tank mounted on a truck with the hatch open for loading; and 
         FIG. 8  is a front view of an access platform, the gangway and the safety cage positioned above the hatch of a dry bulk material tank mounted on a truck returning from loading in the opposite direction of  FIG. 7  with the hatch open and cage floor raised for closing the hatch. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is related to a safety cage and gangway that is particularly suitable for use when opening and closing the hatch of a tanker truck and in particular a dry bulk material tanker truck. Although primarily described herein in terms of its use with tank trucks and service station platforms, it will be clear that the present invention can also be used in connection with a variety of other mobile containers and service station configurations. The invention will be described with reference to the figures forming an integral non-limiting part of the instant specification. Throughout the description similar elements will be numbered accordingly. 
       FIG. 1  illustrates a tanker vehicle in the form of a dry bulk material tank truck  11  positioned for servicing at a standard hatch opening and closing station that includes a worker access or service platform  12  with a floor  13 , typically supported by one or more pillars  14 , and a stairway or ladder  16 . Typical dry bulk material handling tanker vehicles have a hatch  17  on the top of a tank  18  with a hatch cover  19  which is pivotally hinged to the hatch  17  on a horizontal axis  21  extending in the longitudinal direction of the vehicle, that is, in a fore and aft direction. The open position of the hatch cover is shown by broken lines  22 . 
     In order to enhance the safety of workmen who open and close the hatches of the tanker vehicles, a safety cage  20  is provided, which is designed to be placed in encompassing relation to the hatch  17 . The safety cage  20  is supported on the free end of a gangway  30 . As more fully discussed below, gangway  30  includes an access stairway  33  having steps that may be self leveling and body  34  supporting the stairway  33 . Gangway  30  is affixed to platform  12  so that it can be raised to a stored positioned, as shown in  FIGS. 3A and 3B , and lowered to an access position, as shown in  FIGS. 4A and 4B . Access to tank trucks of differing heights is facilitated by the use of self leveling steps in stairway  33 . 
     As shown in  FIG. 1 , the access stairway  33  of gangway  30  has been lowered to its safety enhancing position in which the bottom of the safety cage  20  encircles the hatch  17  and rests on the top of the tank  18  of the tank truck  11 . In a preferred embodiment, the bottom of the safety cage  20  includes a rubber padding, which reduces scratching and movement between the cage  20  and the tank  18 . 
     Referring to the embodiment shown in  FIGS. 2 through 6 , the safety cage  20  forms an open-ended quadrilateral shape and is comprised of two opposing upright sides  40  and  50 , a joining upright side  60 , and a partial pivotable floor  70 . Floor  70  is positioned adjacent to the gangway  30 . The safety cage  20  is open-ended to allow access from platform floor  13  and gangway  30  to floor  70  of cage  20 . To provide additional safety, cage  20  may be only partially opened between gangway  30  and floor  70  of cage  20  or include an entry way that is capable of being closed when a worker is within cage  20 . 
     The first upright side  40  includes a bottom horizontal rail  41 , an intermediate horizontal rail  42 , and an upper horizontal rail  43 . The first upright side  40  also includes a first vertical rail  44  positioned adjacent to the gangway  30 , an intermediate vertical rail  45  that intersects the horizontal rails  41 ,  42 , and  43 , and a third vertical rail  46  positioned adjacent to joining upright side  60 . Bottom horizontal rail  41  is secured to the lower end of the vertical rails  44 ,  45 , and  46 , intermediate horizontal rail  42  is secured in approximately the middle of the vertical rails  44 ,  45 , and  46 , and upper horizontal rail  43  is secured to the upper end of the vertical rails  44 ,  45 , and  46 . The horizontal rails  41 ,  42 , and  43  and vertical rails  44 ,  45 , and  46  are rigidly secured at their respective points of intersection by techniques such as welding or providing bolt-type attachments. 
     The second upright side  50 , which opposes first upright side  40 , includes a bottom horizontal rail  51 , an intermediate horizontal rail  52 , and an upper horizontal rail  53 . Similar to the first upright side  40 , the second upright side  50  also includes a first vertical rail  54  positioned adjacent to the gangway  30 , an intermediate vertical rail  55  that intersects the horizontal rails  51 ,  52 , and  53 , and a third vertical rail  56  positioned adjacent to joining upright side  60 . Bottom horizontal rail  51  is secured to the lower end of the vertical rails  54 ,  55 , and  56 , intermediate horizontal rail  52  is secured in approximately the middle of the vertical rails  54 ,  55 , and  56 , and upper horizontal rail  53  is secured to the upper end of the vertical rails  54 ,  55 , and  56 . The horizontal rails  51 ,  52 , and  53  and vertical rails  54 ,  55 , and  56  are rigidly secured at their respective points of intersection by techniques such as welding or providing bolt attachments. 
     The joining upright side  60  includes an intermediate horizontal rail  62  and an upper horizontal rail  63 . The ends of horizontal rails  62 ,  63  are secured to vertical rail  46  of the first upright side  40  and vertical rail  56  of the second upright side  50 . In the embodiment shown in  FIGS. 3 through 6 , vertical rails  46  and  56  are taller than the remaining vertical rails  44 ,  45 ,  54 , and  55 . Upper horizontal rail  63  is positioned between the upper ends of vertical rails  46  and  56  and intermediate horizontal rail  62  is positioned in approximately the middle of vertical rails  46  and  56 . Vertical rails  46  and  56  are generally U-shaped with their open ends facing inward towards each other. The horizontal rails  62  and  63  and vertical rails  46  and  56  are rigidly secured at their respective points of intersection on the outer back side of the U-shape of vertical rails  46  and  56  by techniques such as welding or providing bolt attachments. 
     The joining upright side  60  further includes a gate  80  that vertically slides relative to vertical rails  46  and  56 . In the embodiment shown in  FIGS. 3 through 6 , the gate  80  includes a bottom horizontal member  81 , a top horizontal member  84 , and two intermediate horizontal members  82  and  83 . Each horizontal member has a handle  85  extending inward towards the center of cage  20 . Gate  80  also includes a first vertical member  86  positioned adjacent to and within the U-shape of vertical rail  46  and a second vertical member  87  positioned adjacent to and within the U-shape of vertical rail  56 . The horizontal members  81 ,  82 ,  83 , and  84  are positioned between vertical members  86  and  87 . Typically, first and second vertical members  86  and  87  are approximately the same height as vertical rails  46  and  56 . 
     As shown in more detail at  95  in  FIGS. 4B &amp; 4C , vertical rails  46  and  56  have cut-out portions  90  along the back side of the respective U-shapes with a roller  91 , such as a nylon roller, affixed therein. In the embodiment shown, each rail  46  and  56  includes two cut-out portions  90  and rollers  91 . Each roller is positioned and stabilized inside the cut-out portion  90  by pin  92 . The pin  92  is inserted through one lateral side of the U-shape of the respective vertical rail  46 ,  56 , through the roller  91 , and then through the opposing lateral side of the respective vertical rail  46 ,  56 . Pin  92  extends parallel with the first and second upright sides so that the roller  91  rotates around an axis that is parallel with the first and second upright sides  40  and  50 . Vertical member  86 , shown in  FIGS. 5A &amp; 5B , is positioned adjacent to the rollers  91  on vertical rail  46  and vertical member  87 , also shown in  FIGS. 5A &amp; 5B , is positioned adjacent to rollers  91  on vertical rail  56 . Gate  80  is held in place and unable to fall away from joining side  60  because of the position of vertical members  86  and  87  within the U-shape of vertical rails  46  and  56 . Alternatively, instead of forming a U-shape, vertical rails  46  and  56  have stop members or gate  80  has holding means to restrain gate  80  from falling away from joining side  60 . Further, tabs  93  affixed at the upper end of vertical members  86  and  87  and positioned to extend at least partially over a portion of the U-shape of vertical rails  46  and  56  keep gate  80  from sliding below cage  20 . Alternatively, stops affixed to the bottom of the U-shape of vertical rails  46  and  56  keep gate  80  from sliding below cage  20 . 
     As shown in  FIGS. 5A and 5B , when a worker grasps handle  85  and applies upward force to gate  80 , vertical members  86  and  87  slide upward along rollers  91  and within the U-shape of vertical rails  46  and  56 . Because joining upright side  60  does not have a bottom horizontal rail, a gap or opening is formed in cage  20  allowing the hatch cover  19  of tank truck  11  to be fully opened so that the top of the hatch cover  19  rests on the upper part of one lateral side of the tank  18  of tank truck  11 . 
     Spring loaded reels  88  may be used to assist movement of gate  80  in the upward direction along rollers  91  and are beneficial in preventing cage  20  from lifting upward due to the upward force and movement of gate  80 . In the embodiment shown, three spring loaded reels  88  are affixed to intermediate horizontal rail  62  at approximately equal spacing between vertical rails  46  and  56 . As more clearly shown in  FIG. 6A , the reels  88  each include cables  89 , which extend from the reels to the bottom horizontal member  81  of gate  80 . Alternatively, counterweights may be used to assist movement of gate  80 . 
     Partial pivotable floor  70  of cage  20  is positioned between the two opposing upright sides  40  and  50  and at the opposing end of cage  20  from joining upright side  60 . As shown in  FIGS. 2 and 6B , floor  70  is generally quadrilateral in shape and has a first side  71  adjacent to gangway  30 , a second side  72  adjacent to upright side  40 , a third side  73  opposing first side  71 , and a fourth side  74  adjacent to upright side  50 . 
     As more fully shown in  FIG. 2 , bottom horizontal rails  41  and  51  include stops or tabs  75  that support floor  70  at the intersection of sides  72  and  73  and the intersection of sides  74  and  73 . Tabs  75  are typically welded to bottom horizontal rails  41  and  51  but other attachment or forming techniques may be used but must be rigid and secure enough to support the weight of a worker. Floor  70  also includes a pivot axis  76  that runs along first side  71  of floor  70  and connects to first vertical rails  44  and  54  of opposing lateral sides  40  and  50 , respectively. As shown in  FIGS. 6A and 6B , floor  70  rotates around pivot axis  76 . Tabs  75  stop floor  70  from rotating to a position below bottom horizontal rails  41  and  51  of cage  20 . Stops may also be located on or approximate to vertical rails  44  and  54  to stop floor  70  from rotating to a position beyond vertical rails  44  and  54 . 
     In the embodiment shown, pivot axis  76  extends through first vertical rail  44 , through floor  70  along first side  71 , and then through first vertical rail  54 . Pivot axis  76  is secured on the outer side of the first vertical rails  44  and  54  using a bolt and nut type assembly, which secures axis  76  to cage  20  but still allows floor  70  to rotate with respect to axis  76 . 
     As shown in  FIGS. 7 ,  6 A, and  6 B, when a worker standing on the upper part of the tank  18  of tank truck  11  applies upward force to floor  70 , floor  70  pivots with respect to axis  76  to an upward position. The upward position is shown in  FIG. 6B  and is also illustrated in  FIGS. 6A and 7  by dotted lines. When floor  70  is in the upward position, an opening is formed between cage  20  and hatch  17  of tank  18 . The opening is large enough for the hatch cover  19  of hatch  17  to be fully opened so that the top of the hatch cover  19  rests on the upper part of one lateral side of the tank  18  of tank truck  11 . After the hatch cover  19  is opened, floor  70  is again lowered to its downward position either resting on tabs  75  or a portion of tank  18 , whichever is higher, so that the worker can walk safely back to the gangway  30  and platform floor  13 . 
     As discussed above, gangway  30  includes an access stairway  33  having steps and a body  34  for supporting the stairway  33 . Gangway body  34  typically incorporates treads for securing the steps of stairway  33 . Gangway  30  also includes vertical posts  35  extending upward and approximately in line with the vertical rails  44 ,  45 ,  46  of cage  20  on a first lateral side  31  and vertical posts  35  extending upward and approximately in line with vertical rails  54 ,  55 ,  56  of cage  20  on a second lateral side  32 . Handrail  36  connects vertical posts  35  on the first lateral side  31  and handrail  37  connects vertical posts  35  on the second lateral side  32  of gangway  30 . The handrail of gangway  30  may be extended on one or both sides to block the exit so that a worker is unable to easily access the access or ladder  16  while the gangway is in the down position. In the embodiments shown, handrail  37  is extended. 
     As discussed above, gangway  30  is connected to platform  12  and is pivotable between a raised stored positioned, as shown in  FIGS. 3A and 3B , to a lowered access position, as shown in  FIGS. 4A and 4B . Frequently, at least the first and last steps of stairway  33  are self leveling so that the gangway  30  can adjust to varying heights of tank trucks and resting positions of cage  20 . For example, as shown in  FIG. 1 , gangway  30  is positioned parallel with platform  12  and the bottom of cage  20 . In contrast, as shown in  FIGS. 7 and 8 , gangway  30  is positioned at a downward angle with platform  12  and the bottom of cage  20 . 
     Cage  20  is supported on the free end of gangway  30 . In the embodiment shown, a portion of body  34  of gangway  30  extends under a portion of cage  20  including first vertical rails  44  and  54  of lateral sides  40  and  50 , respectively. Cage  20  is secured to gangway  30  by a bolt  38  extending through the portion of body  34  extending under cage  20  and into first vertical rail  44  of lateral side  40 . Cage  20  is also secured to gangway  30  by a bolt  38  extending through the portion of body  34  extending under cage  20  and into first vertical rail  54  of lateral side  50 . The portion of body  34  that extends under cage  20  is positioned low enough so that it will not interfere with the pivoting of floor  70  about axis  76 . Other securing mechanisms may also be used to secure cage  20  to gangway  30 . Furthermore, cage  20  may be secured directly to platform  12  thereby eliminating the need for a gangway. 
     It should be noted that there are several configurations suitable for the design of cage  20 , and the number of vertical and horizontal rails and members discussed above are for example only and represent but one of these configurations. Other configurations altering the number and positions of rails and members could be employed to demonstrate the invention. Further, several configurations suitable for the design of gangway  30  and the number of posts and steps discussed above are for example only and represent but one of these configurations. Other configurations altering the number and position of posts and steps could be employed to demonstrate the invention. All configurations known in the art are intended to be encompassed by the present invention and the description and drawings should not be deemed to narrow the scope of the present invention in any way. 
     In performing servicing operations, gangway  30  is in its stored position so that safety cage  20  is also in an elevated position. The tank truck  11  is driven beneath the safety cage  20 , and the gangway  30  and safety cage  20  are then lowered to the safety enhancing position shown in  FIG. 1  wherein the cage rests on the top of tank  18  of tank truck  11 . Gangway  30  may be lowered using varying techniques such as by releasing a foot lock on the body of gangway  30  or by pneumatic or hydraulic actuators. Extended handrail  37  blocks the stairs or ladder  16  of the platform  12  so that the worker is hindered from exiting without raising the gangway  30  and cage  20  to the stored position. After the cage is lowered to its safety enhancing position, the worker opens the latches that secure hatch cover  19  to hatch  17 . The hatch cover  19 , however, is not capable of being pivoted to its fully open position shown in broken lines  22  because of the bottom horizontal member  81  and its corresponding handle  85 , which is spaced laterally from the hatch cover a distance less than the width of the hatch cover  19 . As shown in  FIG. 8 , upon applying upward force to gate  80 , the worker can then fully open hatch cover  19  by pivoting the hatch cover  19  under extended gate  80 . Gate  80  is then released so that it returns to its lowered position and the worker exits the safety cage  20  and returns to platform  12 . The gangway  30  and cage  20  are then raised such as by exerting force downward on extended handrail  37  of gangway  30  until the gangway has raised up enough to allow the foot lock to engage or by pneumatic or hydraulic actuators. In the stored position, extended handrail  37  no longer blocks the stairs or ladder  16  of the platform  12  so the worker can easily exit the platform  12 . The truck  11  is then driven to a loading station, not shown, to receive bulk material such as cement. 
     Alternatively, if the tank truck  11  approaches the service station in the opposite direction or hatch cover  19  was pivotally hinged to hatch  17  on a horizontal axis on the opposing side of hatch  17  to horizontal axis  21  (such as shown in  FIG. 7 ), the hatch cover  19  would not be capable of being pivoted to its open position because of floor  70 , which is spaced laterally from the hatch cover a distance less than the width of the hatch cover  19 . However, the hatch cover  19  can be opened by applying upward force to floor  70 , which causes floor  70  to pivot with respect to axis  76  to the upright position depicted by dotted lines in  FIG. 7 . After the hatch cover  19  is fully opened, floor  70  can be released so that it returns to its downward position either resting on tabs  75  or a portion of tank  18 , and the worker can exit the safety cage  20  and return to platform  12 . The gangway  30  and cage  20  are then raised, and the truck  11  is driven to a loading station, not shown, to receive bulk material such as cement. 
     After material has been loaded, tank truck  11  is then driven back to the servicing station where a worker closes the hatch cover  19 . The hatch cover  19  is closed using the same techniques discussed above. The technique used, pivoting of the floor  70  or lifting of gate  80 , depends on the direction that the tank truck  11  approaches the service station and which side the hatch cover  19  is hinged to the hatch  17 . 
     Optionally, gates and/or floor panels may also be added to other sides of cage  20 . For example, if the hatch cover  19  opens on a horizontal axis perpendicular to axis  21  and extending in the lateral direction of the vehicle, upright sides  40  and/or  50  may be configured to include a gate similar to gate  80  and the bottom horizontal rail  41  and  51 , respectively, would be at least partially removed or positioned so that it does not interfere with hatch cover  19 . Alternatively, upright sides  40  and/or  50  may be configured to include a floor panel similar to the configuration of floor  70  with a pivoting axis. 
     While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example, and not limitation. It will be apparent to persons skilled in the relevant art(s) that various changes in form and detail can be made therein without departing from the spirit and scope of the present invention. In fact, after reading the above description, it will be apparent to one skilled in the relevant art(s) how to implement the invention in alternative embodiments. Thus, the present invention should not be limited by any of the above described exemplary embodiments. 
     In addition, it should be understood that the figures, which highlight the functionality and advantages of the present invention, are presented for purposes of example only. The architecture of the present invention is sufficiently flexible and configurable, such that it may be used in ways other than that shown in the accompanying figures. 
     Further, the purpose of the Abstract of the Disclosure is to enable the U.S. Patent and Trademark Office and the public generally, and especially the scientists, engineers, and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The Abstract of the Disclosure is not intended to be limiting as to the scope of the invention in any way.