Abstract:
An adjustable height jib is disclosed for an arm of a hook-lift hoist for loading of equipment, containers or the like onto a truck for transport. The jib has an elongate body with a hook located on each of its opposing end portions. The jib is mounted on the arm for pivotal movement between a first position for loading containers of a first height and a second position for loading containers of a second height. A lock secures the jib in either position. A feature of the adjustable height jib is that, upon release of the lock, it will pivot between positions as the hook-lift hoist is operated toward the loading position.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The invention relates generally to hook-lift hoists mounted on a wheeled chassis and, more specifically, to a hook-lift hoist that has a jib that is adjustable in length to accommodate containers for loading and transport by the hoist of two different heights.  
         [0002]     Hook-lift hoists have been in common use, particularly in European countries, for a number of years. The hoist has a pivotable L-shaped arm with a hook on its distal end portion or jib that is used to engage a detachable truck box. The hook of the jib engages a loading bar of the container or truck box and the arm is pivoted to lift the container onto the chassis for transport of the container and its contents to any location.  
         [0003]     The truck box containers are manufactured in a range of sizes, each having a characteristic size and rated weight capacity. In general, the larger the container, the larger its rated weight capacity and the higher from the ground its loading bar that is to be engaged by the hook on the jib of the hoist. In the past, hoists have generally been engineered to have a loading capacity matched to the maximum loaded weight of the container it can load and transport. Accordingly, the hook of a hoist had a preset height corresponding to the loading bar of the matching container.  
         [0004]     It has become known also to provide the truck chassis with a lift mechanism for tilting of the box atop the chassis to dump the contents of the box rearwardly of the truck. Hook-lift hoists allow for a single truck chassis to be used with a wide variety of truck boxes, each of which has a distinct and advantageous use. A single truck chassis with a hook-lift -hoist can be used, for example, to load, transport and dump open-topped waste receptacles to a disposal site; to load, transport, and unload shipping containers; to mount, use, and dismount road maintenance equipment, such as a salt spreader; to load, transport, and unload wheeled equipment; and so on. This functional versatility makes hook-lift hoists an economical vehicle for transport industries, particularly the street and highway maintenance departments of municipalities, states, and other governmental entities where budgetary constraints and the variety of tasks that must be performed make these multi-purpose vehicles an attractive choice.  
         [0005]     Given the diversity of containers and other types of equipment that are to be loaded and transported on hook-lift hoists, it has become desirable to be able to load and transport containers and other equipment of more than one size onto a hook-lift hoist.  
       SUMMARY OF THE INVENTION  
       [0006]     In accordance with the present invention, a hook-lift hoist is provided which has a jib accommodates the loading and transport of containers of two different sizes. The hoist includes a hook-lift arm that has a jib segment or member. The jib member terminates at its free end portion with a hook for releasably grasping containers and the like. In the preferred embodiment, the jib member pivots on the hook-lift arm between an extended and shortened position to engage for loading containers or the like having loading bars that are at different heights.  
         [0007]     The jib member has a pair of hooks, one at each end portion. The jib is mounted on the distal end of the hook-lift arm about a pivot axis that is closer to one of the end portions than the other. Pivoting the jib about the pivot axis by 180 degrees pivots the jib end-for-end between a first position where a first of the hooks is in operating position and a second position where a second of the hooks is in operating position. Since the pivot axis is closer to one of the hooks than the other, the working length of the jib changes as the jib is pivoted between the two positions. A keeper or latch secures the jib in either selected position.  
         [0008]     Accordingly, an object of the invention is to provide a hook-lift hoist that can load containers or other equipment of more than one height.  
         [0009]     Another object of the invention is to provide a hook-lift hoist wherein the jib is of adjustable length to engage containers of the like of different heights.  
         [0010]     A further object of the invention is to provide a hook-lift hoist wherein the jib pivots between two working lengths by gravity alone during operation of the hook-lift hoist without the need for powered or manual adjustment.  
         [0011]     These and other objects of the invention will be understood by a person skilled in the art upon a review of the specification, the associated drawings, and the appended claims.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a side view of a hook-lift hoist of the present invention including an associated truck and illustrating a container for loading onto the hoist.  
         [0013]      FIG. 2  is an enlarged end view of an adjustable height jib of the present invention.  
         [0014]      FIG. 3  is an enlarged top view of the adjustable height jib of  FIG. 2 .  
         [0015]      FIG. 4  is an enlarged side view of the adjustable height jib of  FIG. 2 , and includes an exploded view of a pivot pin and lock pin of the adjustable height jib.  
         [0016]      FIG. 5  is a side view of the hook-lift hoist of  FIG. 1  showing retraction of the jib member.  
         [0017]      FIG. 6  is a side view of the hook-lift hoist of  FIG. 1  showing movement of the hook-lift arm to a loading position wherein the jib member has pivoted toward its second position.  
         [0018]      FIG. 7  is a side view of a hook-lift hoist of  FIG. 1  in its loading position for a container of a reduced height.  
         [0019]      FIG. 8  is a side view of a hook-lift hoist of  FIG. 1  with the jib pivoted to its first position and in its loading position for a container of an elevated height. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0020]     Illustrated in  FIG. 1 , generally at 10, is a dual capacity hook-lift hoist that is mounted a truck  12  having a chassis  14  and cab  16  supported on front wheels  18  and rear wheels  20 . The hook-lift hoist  10  is used to load and unload objects on the truck  12  such as containers, equipment, and the like and, if desired, to tilt the loaded object for dumping of its contents. A platform  22  is shown in  FIG. 1  as an example of an object to be loaded by the hook-lift hoist  10 . A prior art hook-lift hoist  10  which may be altered to include the present invention is a Model SL-180 hoist sold by SwapLoader USA, Ltd., and as described in U.S. Pat. No. 5,601,393, which is incorporated herein by this reference.  
         [0021]     The operation of a hook-lift hoist  10  is well known in the art and may be exemplified by the apparatus and operation described in the &#39;393 patent. Generally, the hook-lift hoist  10  includes a mainframe  24  that is secured to the chassis  14  rearwardly of the cab ( FIG. 1 ). An articulated hook-lift arm  26  is mounted to the mainframe  24  for pivotal movement about a horizontal axis, indicated at  28 , transverse to the truck  12 . The hook-lift arm  26  has three main components, an inner or base segment  30 , a middle segment  32 , and a jib member  34 , as best illustrated in  FIGS. 6 and 7 . The inner segment  30  includes a frame that interconnects the inner segment  30  to the mainframe  24  for pivotal movement about the aforementioned horizontal transverse axis. In the prior art device, located at the free or distal end portion of the jib member  34 , is a single hook  50 .  
         [0022]     The hook-lift arm  26  is pivoted by a pair of hydraulic cylinders  52  ( FIGS. 6 and 7 ) that are supplied with pressurized hydraulic fluid by a hydraulic fluid supply system. At the initiation of the loading cycle, the hook-lift arm  26  is supported on the mainframe  24 . A jib cylinder (not shown) is extended so that the jib member  34  is adjacent the cab  16  ( FIG. 1 ). From this transport position, the jib member  34  is moved rearwardly by retraction of the jib cylinder, as illustrated in  FIG. 5 . The cylinders  52  are extended to pivot the middle segment  32  and the support jib member  34  relative to the inner segment  30  ( FIG. 6 ). As the cylinders  52  extend further, the hook-lift arm  26  now pivots at the rearward or inner end portion of the inner member  30  about the axis  28  ( FIG. 7 ). At full extension of the cylinders  52 , the hook  50  is positioned below the mainframe  24  in a hooking position for engagement with a ground-supported object to be loaded on the truck  12 , such as a platform  22 .  
         [0023]     Upon engagement of the platform  22  with the hook  50 , the cylinders  52  are retracted to pivot the hook-lift arm  26  upwardly and forwardly, raising the forward end of the platform  22  off the ground and drawing the platform  22  closer to the truck  12 . Continued retraction of the cylinders  52  raises the forward end portion of the platform  22  above the rearward end portion of the truck  12  whereupon the bottom of the platform  22  will be brought into contact with a pair of flanged rollers which serve to decrease the force required to drag the platform  22  onto the truck  12  and to keep it centered relative to the truck  12 . Full retraction of the cylinders  52  brings the hook-lift arm  26  to the same, earlier described position of  FIG. 5  where it and the platform  22  are supported on the mainframe  24 . The jib cylinder  62  is then extended to move the platform  22  horizontally forwardly to a storage and transport position. It will be appreciated that the sequence just described is reversed to unload a platform  22  that has been previously loaded on the truck  12 .  
         [0024]     The improvement of the present invention is a modification to the jib member  34  by the addition of a pivoting jib  70 , shown in expanded view in  FIGS. 2-4 . The pivoting jib  70  has an elongate body section  72  that terminates at each end portion with a hook, namely hook  50  and hook  74 . The pivoting jib  70  is mounted for pivotal movement about pivot axis  76  relative to the jib member  34  by a pivot pin  78  that is mounted in the sidewalls  80   a  and  80   b  of the jib member  34  and passes through a pivot hole  82  in the pivoting jib  70 . Accordingly, the pivoting jib  70  can move between a first position, as illustrated in  FIGS. 1, 2 ,  4 , and  5 , to a second position, as illustrated in  FIG. 7 . The pivot hole  82  is located closer to the hook  50  than to the hook  74 . Accordingly, movement of the pivoting jib  70  between the first position and the second position will effectively elongate the jib member  34  so that the hook  74  is positioned lower or closer to the ground than the hook  50  when in position to load an object ( FIG. 7 ). The pivoting jib  70  is fixed in its desired position by a lock pin  84  ( FIGS. 2 and 4 ) that includes a graspable handle  86  and a release pin  88 . The lock pin  84  passes through a corresponding opening in the pivoting jib  70  to hold it in position when the lock pin  84  is in place but allow pivotal movement of the pivoting jib  70  when the lock pin  84  is removed. The release pin  88  prevents the lock pin  84  from being dislodged from its locking position unless the same is intended by an operator. A second position lock pin aperture  90  is provided in the pivoting jib  70  to hold the jib in its second position, as will be described-in detail below.  
         [0025]     In operation, for example when the pivoting jib  70  starts in its first position, as illustrated in  FIG. 1 , the jib cylinder is retracted to move the hook-lift arm  26  to the position of  FIG. 5 . The operator then removes the lock pin  84  and initiates movement of the hook-lift hoist  10  to pick up a container. As the hook-lift hoist apparatus  10  is moved, the hoist arm  26  begins to raise toward the position illustrated in  FIG. 6 . As the arm  26  tilts up, the pivoting jib  70  will pivot about the pivot axis  76  by the action of gravity, becoming vertical when the main orientation of the jib member  34  is horizontal ( FIG. 6 ). Further movement of the hook-lift arm  26  will bring it to the loading position of  FIG. 7  where the pivoting jib  70  is once more in parallel alignment with the jib member  34 , although it has now moved to its second position wherein the second lock aperture  90  is now aligned with the lock pin position of the jib member  34 . The operator will reinsert the lock pin  84  and release pin  88  to fix the pivoting jib  70  in its second position for picking up a container. In a similar manner, if the pivoting jib  70  is initially in its second position, operation of the hook-lift arm will result in pivotal movement of the pivoting jib  70  to the first position.  
         [0026]     Alternatively, the jib member  34  may start with the jib  70  in the extended position, as illustrated in  FIG. 8 , although it is desired to load a platform of reduced height. The same procedure described above is followed to change the position of the pivoting jib  70  to accommodate the reduced height platform.  
         [0027]     The loading bars of containers and other equipment to be loaded by the hook-lift hoist are at standardized, predetermined height intervals. Two common heights are 36 inches and 54 inches. Accordingly, in the preferred embodiment, the movement of the pivoting jib  70  from its first position to its second position will result in a change from a hook  50  height to accommodate a container having a loading bar height of 54 inches to the hook  74  having a height to accommodate a container having a loading bar height of 36 inches.  
         [0028]     The foregoing description and drawings comprise illustrative embodiments of the present inventions. The foregoing embodiments and the methods described herein may vary based on the ability, experience, and preference of those skilled in the art. The foregoing description and drawings merely explain and illustrate the invention, and the invention is not limited thereto, except insofar as the claims are so limited. Those skilled in the art who have the disclosure before them will be able to make modifications and variations therein without departing from the scope of the invention.