Patent Publication Number: US-2003221908-A1

Title: Foldable safety apparatus for an upper region of a ready-mix concrete truck

Description:
TECHNICAL FIELD  
       [0001] The present invention related generally to ready-mix concrete trucks, and more particularly, to safety apparatus including a safety railing or guard for an elevated element or platform on a ready-mix truck which railing is deployable above and in outwardly extending relation to the elevated element or platform for providing a passage for movement onto and off of the element or platform and also protection against falling for a person or operator when on the elevated element or platform and when moving onto or off of the element or platform, the railing or guard being storable when the element or platform is not in use so as to be less likely to come into contact with elevated structures, apparatus, equipment, and/or objects typically located in the loading area of a concrete plant where ready-mix trucks are loaded with material, and at job sites and other locations.  
       BACKGROUND ART  
       [0002] Commonly, persons such as concrete plant operators, drivers, laborers and the like, are required to occasionally climb to elevated regions on a ready-mix concrete truck, particularly, elevated regions in the vicinity of the elevated open end of the rotatable concrete mixing drum thereof, for inspecting the contents thereof, and/or for servicing, maintaining, or cleaning aspects of the truck located in this region, such as the fill chute, and the like, and for placing admixes and other agents in concrete present in the drum. Typically, the truck includes a ladder or other apparatus which can be climbed for accessing the elevated region of the truck, and, in many instances, a platform is provided adjacent the upper end of the ladder, on which a person can stand for inspecting or performing work required at the elevated location. To allow proper access to the equipment at the elevated location, the upper regions of the ladder and the platform, if provided, will typically be 7 to 10 feet above the ground or other surface on which the truck is located, making it desirable to provide safety apparatus for persons thereon.  
       [0003] One known safety apparatus usable is a harness or sling to be worn by the person and attachable to an upper region of the truck. However, it is anticipated that sometimes the person will forget to wear the apparatus, or intentionally will not wear it due to discomfort, heat, or for other reasons. Also known is to use a chain or movable guard railing section or gate securable between supports on opposite sides of an access region of an elevated region or platform. However, such known chains and gates provide no fall protection for a person when moving onto or off of an elevated platform and at other times when the chain or gate is not in place. Securing a chain or gate once a person is on the platform, and unsecuring it to leave, can also require a person to make difficult moves, such as turning around on the platform, which can increase potential for falling and injury. Additionally, and importantly, ready-mix trucks often must be maneuvered into position beneath a fill chute of a concrete plant for receiving a load of concrete therefrom, and often will have to be maneuvered at job sites where the concrete is to be placed, at which locations various structures, apparatus, equipment and other obstacles at about the same height as the upper areas of the ready-mix truck may be present, thereby providing a danger of damage to the structure and/or equipment and/or any elements on or protruding from upper regions of the truck which come into contact with the equipment or other obstacles. In this regard, to minimize the occurrence of accidental contact between the elements on the upper regions of a ready-mix truck and equipment and other obstacles present at cement plants, job sites, and the like, is desirable to minimize the profile of the upper regions of the truck and the number of items extending outwardly therefrom.  
       [0004] Thus, what is sought is safety apparatus for an elevated region of a ready-mix concrete truck which provides desired fall protection for a person working in the elevated region, and/or when entering or leaving the region using a ladder or other climbable element, which safety railing or guard provides easy access to and from the elevated region, can be stored when not in use in a non-obtrusive manner or location with respect to the front and rear profile of the truck, and which safety railing or guard can be easily, safely, and conveniently moved between its deployed and stored positions.  
       DISCLOSURE OF THE INVENTION  
       [0005] According to the present invention, safety apparatus for an elevated region of a ready-mix concrete truck which provides many of the sought after properties discussed above, is disclosed. According to a preferred aspect of the invention, the safety apparatus includes at least one elongate, rigid railing element having opposite end portions and a concave portion disposed therebetween, the end portions being supported by structure on the truck for pivotal movement of the railing element between a deployed position located generally above and extending around a peripheral portion or region of the elevated region, and a stored position angularly related to the deployed position above or below the deployed position, and an element positionable in a predetermined position for holding the railing element in the deployed position. In the deployed position, the railing element provides a passage through which a person can move between a ladder or other climbable element and the elevated region while providing protection against the person falling outwardly away therefrom.  
       [0006] Preferably, the element positionable in the predetermined position for holding the railing element in the deployed position includes an elongate arm connected to and extending downwardly from the railing element and connected to a pivotally mounted ladder portion, such that when the ladder portion is pivotally moved to a position for climbing thereon to the elevated region, the railing element is held by the ladder in the deployed position. More particularly, the preferred construction includes a conventional ladder including an upper ladder portion fixedly mounted to the truck, the above-discussed pivotal ladder portion being mounted for pivotal movement relative to the upper ladder portion between a folded position oriented generally parallel to or at a small acute angle to the upper ladder portion and an unfolded position generally parallel to and extending downwardly from the upper ladder portion, and the element positionable for holding the railing element in the deployed position includes an arm connected between the railing element and the lower ladder portion and including a linkage arrangement operable for positioning the railing element in the deployed position when the lower ladder portion is moved to the unfolded position, and positioning the railing element in the stored position when the lower ladder portion is moved to the folded position.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0007]FIG. 1 is a fragmentary simplified schematic representation of one side of a rear end of a representative conventional ready-mix concrete truck including foldable safety apparatus for an elevated region of the truck according to the present invention;  
     [0008]FIG. 2 is a fragmentary simplified schematic perspective representation of the truck and safety apparatus of FIG. 1, illustrating a person in the elevated region;  
     [0009]FIG. 3 is another fragmentary simplified perspective schematic representation of the truck and safety apparatus of FIG. 1;  
     [0010]FIG. 4 is an enlarged fragmentary perspective view of an arm and linkage arrangement of the safety apparatus of FIG. 1, showing connection thereof to a lower ladder portion of a foldable ladder of the truck of FIG. 1;  
     [0011]FIG. 5 is a front view of an elevated platform and the foldable ladder of the truck of FIG. 1 in an unfolded position, for positioning the safety apparatus in a deployed position as shown;  
     [0012]FIG. 6 is another front view of the elevated platform and ladder of the truck of FIG. 1, showing the ladder being moved from the unfolded position (in phantom) to a folded position for moving the safety apparatus from the deployed position (in phantom) to a stored position;  
     [0013]FIG. 7 is another fragmentary perspective view of the truck and safety apparatus of FIG. 1, showing the safety apparatus in the stored position;  
     [0014]FIG. 8 is an enlarged fragmentary perspective view of the foldable ladder and aspects of the safety apparatus, illustrating one embodiment of apparatus for holding the foldable ladder in the folded position for holding the safety apparatus in the stored position;  
     [0015]FIG. 9 is a fragmentary side view of the elevated platform of the truck of FIG. 1, including an alternative railing construction and the foldable safety apparatus of the invention thereon;  
     [0016]FIG. 10 is a fragmentary front view of the elevated platform, railing, and safety apparatus of FIG. 9; and  
     [0017]FIG. 11 is a fragmentary rear view of the elevated platform, railing, and safety apparatus of FIG. 9. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0018] Referring now to the drawings wherein preferred embodiments of the present invention are shown, in FIG. 1, a rear end  10  of a typical ready-mix concrete truck  12  is shown, including foldable safety apparatus  14  constructed and operable according to the teachings of the present invention, for providing fall protection for a person located on an elevated region of truck  12 , as generally denoted by region  16 . Here, elevated region  16  generally includes an elevated platform  18  conventionally mounted to structure on the upper regions of rear end  10  at an elevation of about 7 to 10 feet above a surface  20  on which truck  12  is located, such as the ground or pavement, and also upper regions of a foldable ladder  22  disposed between surface  20  and platform  18 . Truck  10  includes a rotatable hollow drum  24  having an open end  26  which is elevated relative to an opposite end thereof, for receiving ready-mix concrete from a concrete plant (not shown) through a chute  28  mounted on truck  12  in alignment with open end  26 . Drum  24  includes at least one internal helical flight or rib extending therearound (not shown) which mixes the ready-mix concrete in the drum when rotated in a first direction, and dispenses the concrete through open end  26  when rotated in the opposite direction. Truck  12  additionally includes a pair of wheels  30  mounted on a pivotal armature  32  for movement between a position generally in or adjacent to elevated region  16  when not in use, and a lowered position in contact with surface  20  for better distributing heavy loads, as required.  
     [0019] A person such as an operator, driver, or laborer will typically climb ladder  22  to reach platform  18  and stand thereon for performing any of a variety of functions, including, but not limited to, inspecting concrete in or flowing into drum  24 ; placing an admixture, such as a colorant, cure retarder, or other chemical therein; cleaning; maintaining; and/or repairing apparatus in or near elevated region  16 . Platform  18  and ladder  22  can be rendered slippery by the presence of water and/or mud or other slippery agents on the person&#39;s shoes or boots and/or on the surfaces of platform  18  and/or ladder  22 , such that it is possible that the person could fall from platform  18  or ladder  22  when standing thereon or climbing therebetween. Persons have also been known to fall from platforms such as platform  18  and ladders such as ladder  22  due to inattention, and/or loss of grip, and/or improper climbing technique. Due to the height of platform  18  and upper regions of ladder  22 , which as noted above can be about 7 to 10 feet above surface  20 , the possibility of injury from a fall is significant.  
     [0020] Ladder  22  includes an upper ladder portion  34  fixedly mounted to appropriate structural elements of truck  12 , such as straps, braces and the like. Ladder  22  includes a lower ladder portion  36  mounted to upper ladder portion  34  for pivotal movement between an unfolded position extending downwardly toward surface  20  as shown in FIGS. 1, 4 and  5 , and a folded position generally beside and parallel or near parallel to upper ladder portion  34 , as illustrated in FIGS. 6, 7 and  8 .  
     [0021] Referring also to FIGS. 2 and 3, truck  12  includes a fixed safety railing  38  of bent or welded together tubular members, including end portions  40  and  42  fixedly connected to elevated platform  18  adjacent to opposite forward and rear outer corners thereof by welding or other suitable attachment, railing  38  extending upwardly from end portions  40 ,  42  to a pair of bends  44 ,  46 , respectively, located a predetermined distance above platform  18 . Railing  38  extends generally horizontally from bends  44 ,  46  sidewardly generally toward drum  24  and chute  28 , to an inward railing portion  48  which spans a forward to rearward extent of platform  18  along a peripheral edge thereof closest to drum  24 . Fixed safety railing  38  essentially has a U-shape profile when viewed from above or below, extending around the forward and rearward peripheral edges of platform  18  and the sideward peripheral edge thereof closest to drum  24 , such that a sidewardly open access region  50  is defined between upstanding portions of railing  38  between end portions  40 ,  42  and bends  44 ,  46  above a corresponding peripheral edge or region of platform  18 . As shown in FIG. 1, railing  38  is at a representative height, denoted by distance A, above platform  18  of about 36 inches, which provides adequate safety for a person standing on platform  18 , while still allowing the person to reach beyond inward railing portion  48  to chute  28  and other regions of truck  12 . Platform  18  is shown located a representative distance, denoted by distance B, above surface  20 , of about 7 to about 10 feet. Upper ladder portion  34  of foldable ladder  22  extends upwardly to and preferably connects to platform  18  adjacent the connection of end portion  40 ,  42  thereto, such that a person can climb between ladder  22  and platform  18  through access region  50 . When a person is at this height on platform  18 , or is climbing onto or off of platform  18  in or in the vicinity of access region  50 , as illustrated by person  52  in FIG. 2, there is the possibility of being injured by a fall, particularly by falling outwardly away from platform  18  and ladder  22 .  
     [0022] To reduce the possibility of such an injury, foldable safety apparatus  14  is configured and intended for providing fall protection for a person while on platform  18  and climbing or moving between platform  18  and ladder  22 . Apparatus  14  includes a rigid elongate first railing element  54  preferably of tubular metal or other suitable material including a first end portion  56  and a second end portion  58  opposite end portion  56 , and an intermediate portion  60  extending between end portions  56 ,  58 . Intermediate portion  60  shown has an arcuate or curved concave shape defining and extending partially around a passage or area  62 , as shown in FIGS. 2 and 3, above and in alignment with access region  50 , through which the upper body portion of a person, such as person  52 , can pass when climbing onto or off of platform  18 . End portions  56  and  58  are mounted on and supported for pivotal movement relative to, upstanding support members  64 ,  66  mounted to railing  38  adjacent bends  44 ,  46 , respectively. End portions  56 ,  58  are pivotally connected to support members  64 ,  66 , respectively, by suitable pivotal elements, such as pins  68  shown, such that railing element  54  is pivotally movable about a generally horizontal axis between a generally horizontally extending deployed position (FIGS. 1, 2,  3 , and  5 ) and a folded or stored position oriented at a large acute angle to the deployed position, preferably extending downwardly (FIGS. 6 and 7). Here, it should be noted that intermediate portion  60  of railing element  54  has a sideward extent, generally perpendicular to an imaginary horizontal axis through pins  68 , which makes area  62  sufficiently large to allow passage of the upper body of a person therethrough when climbing onto or off of platform  18 , but which still positions railing element  54  for providing fall protection for the person, both when climbing to or from and also when standing on platform  18 . This combination of accessibility and fall protection is a function of the elevation of railing element  54  a suitable distance above distance A, which is preferably about 6 inches or so, which locates railing element  54  about 42 inches above platform  18 , and the outward extent of the concave intermediate portion thereof, as will be discussed.  
     [0023] To optionally and preferably provide additional fall protection for a person climbing between platform  18  and ladder  22 , safety apparatus  14  includes a second railing element  70  also preferably of rigid tubular metal or other suitable construction pivotally supported on and movable relative to a pair of upstanding support members  72  and  74  adjacent opposite sides of the upper end of upper ladder portion  34 , for pivotal movement between a generally horizontal deployed position (FIGS. 1, 2,  3 , and  5 ) and a folded or stored position (FIGS. 6 and 7). Second railing element  70  includes opposite first and second end portions  76  and  78  which are pivotally connected using suitable members, such as pins  80 , to support members  72  and  74 , respectively, and an intermediate portion  82  extending between end portions  76 ,  78 . Intermediate end portion  82  has an arcuate or curved concave shape defining and partially surrounding a second area  84  which, when railing element  70  is in its generally horizontal deployed position, is slightly larger than and located spaced below area  62  defined by railing element  54  essentially forming a passage in combination therewith. Referring more particularly to FIG. 2, such passage is desirably sufficient for a person to pass through when making the transition between platform  18  and ladder  22  while railing elements  54  and  70  provide fall protection for the person, as illustrated by representative person  52 .  
     [0024] Here, it should be noted that although intermediate portions  60  and  82  of railing elements  54  and  70  are shown as having curved or arcuate shapes, other concave shapes, such as rectangular, hexagonal, oval, or the like, and other shapes which provide desired degrees of accessibility and fall protection, can be used, as desired. It should also be noted that although apparatus  14  is shown connected to platform  18  and railing  38  by upstanding support members  64 ,  66  and  72  and  74 , other apparatus or members could be used for positioning and supporting apparatus  14  as desired and required for a particular ready-mix concrete truck application or configuration.  
     [0025] Due to the possibility of space constraints in the loading areas of concrete plants, job sites and other locations, it is preferred that railing elements  54  and  70  be pivotable to stored locations which reduce the overall sideward profile of truck  12 , to lessen the potential for damaging contact with apparatus, equipment and structures located at about the same elevation as the railing elements. It is also desirable for the railing elements, or at least one of them, to serve as a barrier to entry onto platform  18  when the railing elements are in the stored position, such that a person will not be easily able to inadvertently or intentionally climb onto platform  18  without the railing elements being deployed.  
     [0026] Referring more particularly to FIGS. 4, 5 and  6 , lower ladder portion  36  and ladder  22  is mounted for pivotal movement relative to upper ladder portion  34  by a pair of pivots  86 , to allow manually moving lower ladder portion  36  between the unfolded positions (FIGS. 4 and 5) and the folded position (FIG. 6). It is desirable for lower ladder portion  36  to be in its folded position when truck  12  is moving, and when there is otherwise no reason for a driver, operator or other person to be on platform  18 . This coincides with the times when railing elements  54  and  70  are to be in their stored positions, for decreasing the profile of the upper portions of truck  12  when viewed from the front and rear, for reducing the possible occurrence of contact with elevated structures, apparatus, and equipment, and also for providing an impediment or barrier for a person attempting to climb onto platform  18 , or the upper rungs of ladder  22 , for safety purposes.  
     [0027] Generally, at any time that lower ladder portion  36  is unfolded, first and second railing elements  54  and  70  are preferably deployed. To accomplish this, it is desirable that railing elements  54  and  70  be deployable from a location beneath platform  18 , and most preferably by the movement of lower ladder portion  36  from the folded position to the unfolded position, such that the person is less likely to fail to deploy the present safety apparatus. This is preferably accomplished utilizing a combination of an elongate arm  88  and a linkage arrangement  90  connected between lower ladder portion  36  and railing elements  54  and/or  70 . In the preferred embodiment, arm  88  has a lower end connected by a pivot  92  to lower ladder portion  36  adjacent the upper end thereof. Arm  88  includes an upper end pivotally connected by a pivot  94  to a first link  96  of linkage arrangement  90  fixedly connected to railing element  54  at about a perpendicular angle to intermediate portion  60  thereof, as best shown in FIGS. 5 and 6. Linkage arrangement  90  additionally includes a connecting link  98  pivotally connected to both railing element  54  and railing element  70 .  
     [0028] Referring in particular to FIG. 5, when lower ladder portion  36  is unfolded and extending downwardly from and generally parallel to upper ladder portion  34 , arm  88  will hold first link  96  in a downward position, such that railing element  54  fixedly connected to link  96  will be maintained and held in the deployed position, extending generally outwardly as shown. Connecting link  98  is connected between railing elements  54  and  70  so as to position railing element  70  in its deployed position as also shown. Then, referring more particularly to FIGS. 6 and 7, when lower ladder portion  36  is pivotally moved to its folded position, denoted by arrow C, arm  88  is driven or displaced upwardly thereby so as to pivot railing element  54  downwardly, as denoted by arrow D, to its stored position as shown. At the same time, due to the pivotal connection of connecting link  98  between railing elements  54  and  70 , railing element  70  is pivoted downwardly, as denoted by arrow E, to its stored position, as also shown. Deployment of railing elements  54  and  70  is accomplished by pivotally moving lower ladder portion  36  in the direction opposite direction C, which serves to pull or allow arm  88  to move downwardly to pivot railing elements  54  and  70  upwardly to the deployed positions thereof, in the direction opposite arrows D and E, respectively. Here, it should be observed that railing elements  54  and  70  when in their stored positions, are preferably intentionally located so as to effectively serve as barriers to movement of a person onto platform  18  from ladder  22 . It should also be noted that the pivotal movement of lower ladder portion  36  to the position of FIG. 5 is sufficient to hold railing elements  54  and  70  in the deployed position, even when a weight or load is exerted thereagainst, such as in the event an adult person falls or leans against either or both of railing elements  54  and  70 , thus providing the desired safety and fall protection. Contributing reasons for this effect include the weight of lower ladder portion  36  and the mechanical advantage exerted thereby over arm  88  by virtue of the greater distance between the center of gravity of ladder portion  36  and pivot  86  compared to the distance of pivot  92  to pivot  86 , providing an over center clamping or holding effect.  
     [0029] Referring to FIG. 8, it is desirable to provide elements for holding lower ladder portion  36  of ladder  22  in its folded position beside upper ladder portion  34 , both to prevent damage to ladder  22  when truck  12  is moving, and to prevent inadvertent or accidental deployment of railing elements  54  and  70 . This can be accomplished utilizing any suitable structure, including, for instance, a pawl  100  pivotally mounted on lower ladder portion  36  and receivable in a slot  102  between a bracket  104  and a rail of lower ladder portion  34 , pawl  100  being rotatable when in slot  102  to a position for engaging bracket  104  for holding ladder portions  34  and  36  together.  
     [0030] Referring to FIGS. 9, 10 and  11 , foldable safety apparatus  14  is shown directly mounted to a fixed safety railing  38  located a desired distance above platform  18  and operable in the above-described manner, the advantage achieved being the elimination of any necessity for additional support members  64 ,  66 . For instance, the upper portion of fixed safety railing  38  could be located at a distance of about 42 inches above platform  88 , as desired. It should also be remembered that it is contemplated according to the present invention that the present foldable safety apparatus can utilize as few as one or as many as several pivotally mounted railing elements, at different locations above platform  18 , even with platform  18 , and/or below platform  18 , as desired. Thus, a single pivotal railing element could be provided adjacent to the upper portion of safety railing  38 , between railing  38  and platform  18 , or below platform  18 , as desired.  
     [0031] Here, it should be noted that although safety apparatus  14  as disclosed and described above is utilized in association with a fixed railing extending at least partially around an elevated platform of a ready-mix truck, the present invention could be utilized in association or connection with other elevated apparatus and structures, including, but not limited to, just the upper regions of a ladder, or a platform without a ladder per se associated therewith. Additionally, it should be noted that alternative constructions, for instance, the upper end of arm  88  could alternatively be connected to railing element  70  instead of to railing element  54 , and could be connected directly to the railing element, instead of by connecting link  98 . However, an advantage of connection using a linkage arrangement such as arrangement  90  including a link such as link  96  arranged and located as shown is that loads applied against arm  88  when deploying railing elements  54  and  70  are in tension, and any loads exerted, for instance, by a person falling against either railing element  54  or element  70 , are in tension, and thus would not tend to exert a buckling or bending force against arm  88 , or link  96 . Also, use of link  96  enables arm  88  to be spaced a desired distance from other structural elements of truck  12 , including ladder  22 , such that potential pinch points are avoided. In this regard, it should be noted that it is contemplated that arm  88  could be advantageously positioned for use as a hand rail and could be located at any desired location in the vicinity of ladder  22 . Arm  88  could also alternatively be connected to other apparatus on truck  12  so as to be movable for moving the railing element or elements between the stored and deployed position, such as a hand or foot operated lever or the like. The railing element or elements could also be deployed automatically using a fluid cylinder or cylinders, a servo, or other actuator. As noted above, railing elements  54  and  70 , when in their folded positions, reduce the forward and rearward profile of truck  12  compared to when deployed, and provide a sufficient impediment or barrier to moving or climbing onto platform  18 , such that it will be less likely that a person would climb to a dangerous height without first deploying railing elements  54 , and/or  70 . It should be noted, however, that alternatively, railing elements  54  and/or  70  could have a stored position which extends downwardly at a more vertical orientation, or upwardly at a desired orientation, as desired.  
     [0032] Lastly, referring again to FIG. 5, first railing element  54  is shown having an outward horizontal extent, denoted by distance F as measured from pin  68  which is preferably equal to from about 15 to about 24 inches, which has been found to provide an area  62  (FIG. 2) large enough for an average adult male to pass through, while providing adequate fall protection. Similarly, second railing element  70  has an outward extent, denoted by distance G, which is preferably from about 30 to about 42 inches as measured from pin  80  and provides an area  84  (FIG. 2) sufficiently large for passage of a person when climbing onto or off of platform  18 , while providing the desired fall protection for the person. Here, it should be noted that distances F and G are measured from pins  68  and  80 , respectively, the locations of which pins generally correspond to the outer peripheral edge of platform  18  and also access region  50  (FIG. 2). It should also be noted that distances F and G can be different and varied for a desired application or truck, to provide a desired or required space for passage of a person through areas  62  and  84  as well as the level of fall protection sought.  
     [0033] It will be understood that changes in the details, materials, steps, and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention. Accordingly, the following claims are intended to protect the invention broadly as well as in the specific form shown.