Abstract:
An improved boom-mounted jib unit ( 10 ) is provided having an increased range of motion and work envelope, which allows a user to lift heavier loads an otherwise work with less jib interference, as compared with prior jib units. The jib unit ( 10 ) includes a base ( 12 ) and a mounting component ( 28 ) permitting the unit ( 10 ) to be detachable secured to the upper end of a primary boom ( 22 ). The unit ( 10 ) also has a boom arm ( 14 ) made tip of upper and lower arms ( 16, 18 ). The arm ( 14 ) is articulated by a dual piston and cylinder assembly ( 20 ) having first and second piston and cylinder assemblies ( 84, 86 ) coupled between the base ( 12 ) and arm ( 14 ).

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention is broadly concerned with improved jib units of the type which may be mounted on a primary boom to allow a user to lift loads and do other work from a personnel bucket secured to the boom. More particularly, the invention is concerned with such detachable, boom-mounted jib units having a significantly increased range of motion and useful working envelope by provision of a doubly articulating assembly for selective movement of the jib unit when positioned on a boom. Double articulation is provided by means of first and second piston and cylinder assemblies pivotally coupled between the base of the jib unit and the moveable jib arm.  
         [0003]     2. Description of the Prior Art  
         [0004]     Arial booms are used in a variety of contexts in order to raise and lower heavy loads and allow workers to operate from boom-mounted personnel buckets and the like. For example, a vehicle-mounted arial device typically includes a boom which can rotate, pivot up and down, and extend. The boom assembly generally has a lower boom mounted to the vehicle and an upper boom which articulates relative to the lower boom. The tip of the upper boom carries a working platform such as a bucket or basket from which workers can perform various jobs. It is common for this type of arial device to be used in situations requiring the raising and lowering of heavy loads. This task is usually carried out by means of a pivotal jib unit mounted on the tip of the upper boom, with the jib unit supporting a winch assembly.  
         [0005]     U.S. Pat. No. 6,044,991 illustrates such an arial boom device. The jib unit described in the &#39;991 patent has a single piston and cylinder assembly for articulation of the jib arm. This inherently limits the range of motion and useful work envelope of the jib unit. A problem commonly encountered in such cases is that when lifting heavy loads, the jib unit must be positioned in such a location that the load cannot be elevated to a convenient work height. Thus, the user may be forced to bend over the edge of the bucket in order to manipulate the load. This is not only inconvenient, but effectively lessens the loads which the user may be able to handle.  
         [0006]     The prior art describes a vast array of boom designs, both in mobile vehicle-mounted booms and in static units. Some of these designs are illustrated in U.S. Pat. Nos. 4,150,754, 3,774,389, 3,917,088, 4,464,093, 4,660,729, 4,927,315, 6,860,396, 4,027,772, 3,924,776, 4,094,422, 3,991,886, 3,487,964, 4,252,213, 4,222,491, 4,368,824, 4,861,224, 4,456,093, 2004/0262078, 2004/0164042, 3,819,922, 6,843,383, 5,337,854, 4,178,591, 4,582,206, 5,826,859, 4,828,124, 4,053,060, 5,337,854, 4,838,381, 4,063,649, 2,988,040, 4,759,685, GB2148983, GB1400402, DE2807518, DE3633582, DE29801914, DE29619474, DE4203186, DE3112586, SE521093, WO94/27906, EP1512388, EP1000802, and EP0513939.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention overcomes the problems outlined above and provides an improved jib unit of the type designed for detachable connections to the upper end of a primary boom in order to afford greater ranges of motion and useful work envelopes. Broadly speaking, the jib units of the invention comprise a jib arm and a stationary base including coupling structure for selective attachment and detachment of the jib unit to a primary boom upper end. The jib units also includes an articulating assembly operably coupled between the stationary base and jib arm in order to selectively move the jib arm relative to the base. This articulating assembly includes first and second piston and cylinder assemblies operatively pivotally coupled between the stationary base and the jib arm, so that the jib arm is movable in response to extension and retraction of the first and second piston and cylinder assemblies.  
         [0008]     In preferred forms, the jib-mounting coupling structure includes a cylindrical body configured to be received within a socket carried by the upper end of the primary boom. For example, the boom may be equipped with a leveling device for maintaining a personnel bucket in a horizontal position throughout the range of movement of the boom; and this device may be configured to include a socket adapted to receive the cylindrical coupling structure of the jib unit.  
         [0009]     The doubly articulating assembly of the jib unit preferably includes a lower jib arm and an upper jib arm pivotally coupled with the lower jib arm. The lower jib arm is pivotally coupled with the stationary base. In detail, the first assembly is pivotally coupled with the stationary base and the lower jib arm, whereas the second assembly is secured to the lower jib arm and the upper jib arm. In order to minimize the dimension envelope of the articulating assembly, the lower jib arm is positioned between the first and second piston and cylinder assemblies.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a perspective view of a preferred jib unit in accordance with the invention, showing the stowed condition of the unit;  
         [0011]      FIG. 2  is a side-elevational view of the preferred jib unit, shown mounted on a primary boom adjacent a personnel bucket;  
         [0012]      FIG. 3  is a plan view of the jib unit, primary boom, and personnel bucket depicted in  FIG. 2 ;  
         [0013]      FIG. 4  is an enlarged, side elevational view of the unit depicted in  FIGS. 2 and 3 , but showing the jib unit fully extended and in its lowermost position;  
         [0014]      FIG. 5  is a view similar to that of  FIG. 4 , but showing the jib unit fully extended,  FIGS. 4 and 5  together illustrating the range of motion of the jib unit;  
         [0015]      FIG. 6  is an end view of the unit shown in  FIGS. 4 and 5 , but showing the jib arm in its vertical position and carrying a phase-line lifter;  
         [0016]      FIG. 7  is a side elevational view of the jib unit, shown fully extended and in a load-lifting position; and  
         [0017]      FIG. 8  is an end view of the unit shown in  FIG. 7 .  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]     Turning now to the drawings, a jib unit incorporating principles of the present teachings is illustrated in  FIG. 1  and designated generally by the reference numeral  10 . Broadly, the jib unit  10  includes a stationary base  12 , a jib arm  14  including a lower arm  16  and an upper arm  18 , and an articulating assembly  20  operably coupled between base  12  and arm  14  in order to selectively articulate the latter through an extended range of motion. The jib unit  10  is especially designed to be detachably mounted on the upper end of a primary boom  22  (see  FIGS. 2 and 3 ) which also supports a personnel bucket  24 .  
         [0019]     In more detail, the base  12  includes a generally horizontal plate  26  supporting a depending, generally cylindrical mounting component  28  carrying a removable locking pin  30 ; the pin  30  may be alternatively received within a plurality of mounting through-hole pairs  31 . The illustrated through-hole pairs  31  represent substantially orthogonal positions, but more through-hole pairs may be used representing a variety of positions without departing from the scope of the claimed invention. The base  12  also includes a pair of upstanding, laterally spaced apart side frames  32  that are substantially parallel to each other. The horizontal plate  26  and the side frames  32  support the weight of the jib arm  14  and the articulating assembly  20 , as well as any external load on the jib arm  14 , and are therefore constructed of a sturdy and rigid material, such as steel or iron. Reinforcing webs (not shown) extend between the side frames  32  to provide additional rigidity to the base  12 .  
         [0020]     The horizontal plate  26  is preferably between one-sixteenth and one inch thick, and more preferably between one-eighth and one-quarter of an inch thick. Each of the side frames  32  is likewise preferably between one-sixteenth and one inch thick, and more preferably between one-eighth and one-quarter of an inch thick.  
         [0021]     The lower arm  16  comprises a pair of elongated, laterally spaced apart, unitary arms  34  each presenting endmost extensions  36  and  38  separated longitudinally by an elongated and narrower center portion. The endmost extension  36  is substantially downwardly-extending and the endmost extension  38  is substantially upwardly-extending when the jib unit  10  is in the position illustrated in  FIG. 1 . As illustrated in  FIG. 8 , the arms  34  are substantially parallel to each other and of substantially identical shape and size.  
         [0022]     Outboard reinforcement plates  40  and  42  are provided at the regions of the extensions  36  and  38 , and additional reinforcements including cross tubes  39  are interconnected between the arms  34  along the lengths thereof. The reinforcing places  40  and  42  may comprise separate plates rigidly secured to the arms  34 , or may comprising raised portions of the arms  34  integrally formed with the arms  34 . The lower arm  16  is pivotally coupled to upper ends of the side frames  32  of the base  12 . To this end, a laterally extending pivot pin  44  extends through the lower extensions  38  and the corresponding reinforcements  42 , as well as through a journal fitting  46  located between the side frames  32 . The outboard ends of pivot pin  44  are equipped with lobes  48  secured to the adjacent reinforcement  42  by screw  50 . Hence, the lower arm  16  is pivotal about a generally horizontal axis and relative to base  12 .  
         [0023]     The arms  34  are preferably between six inches and three feet in length, more preferably between eight and twenty inches in length; and preferably between one-sixteenth inch and one-half inch in thickness, more preferably between one-eighth and one-half inch in thickness, excluding the reinforcing plates  40  and  42 , which preferably substantially double the thickness of the arms  34 . The shape of the arms  34  illustrated in the various drawings is exemplary, and not limiting, in nature, and it will be appreciated that the arms  34  may be constructed with various different shapes without departing from the scope of the claimed invention.  
         [0024]     Upper arm  18  includes a tubular body  52  having an outermost reinforcing sleeve  54  carrying a hand-actuated positioning pin  56  which is insertable into a through-aperture  57 . The body  52  also supports a hydraulically operated winch and motor assembly  58  and an associated reel  60 . A mounting bracket  62  depends from the underside of body  52  and includes a pair of laterally spaced apart side plates  64 . A tubular extension  66  is slidably received within body  52  and has a pair of spaced apart, pin-receiving positioning apertures  68  and  70 .  
         [0025]     The extension  66  is thus movable between a retracted, stowed position (see  FIGS. 1-3 ) where the pin  56  is inserted through sleeve  54  and positioning aperture  70 , and an extended use position where the extension  64  is shifted outwardly and pin  56  extends through sleeve  54  and positioning aperture  68  (see  FIGS. 4-8 ). The outermost end of extension  66  is also designed to support a detachable working implement such as a pulley unit  72 , secured in place by a detachable pin  74 . The aperture  68  is spaced a sufficient distance from an end of the tubular extension  66  to prevent the creation of a damaging moment between the overlapping portions of the body  52  and the extension  66  when the extension  66  is in the extended use position and supporting a load via the pulley unit  72  or other working implement.  
         [0026]     The body  52  of the upper arm  16  is preferably between six inches and three feet in length, more preferably between twelve inches and eighteen inches in length. The tubular extension  66  is preferably between two feet and twelve feet in length, more preferably between three feet and five feet in length. The diameter of the tubular extension  66  is preferably between one inch and twelve inches in diameter, more preferably between two inches and five inches in diameter. Furthermore, the tubular extension  66  may be substantially solid or substantially hollow.  
         [0027]     The upper arm  18  is pivotally coupled to lower arm  16  by means of pivot pin  76  extending through the outer ends of the extensions  36  and reinforcements  40 , and also through journal  78  extending between the extensions  36 . The pin  76  also has outboard locking lobes  80  secured to the adjacent reinforcements  40  by screws  82 . Hence, the upper arm  18  is pivotal about a generally horizontal axis and relative to the lower arm  16 .  
         [0028]     The articulating assembly  20  includes first and second, hydraulically driven, double acting piston and cylinder assemblies  84 ,  86  (each having a cylinder  84   a ,  86   a  and an extensible rod  84   b ,  86   b ) which are operatively coupled between base  12  and jib arm  14 . In particular, the first piston and cylinder assembly  84  has its rod end pivotally coupled with base  12 , with the cylinder end thereof pivotally secured to extension  36  of lower arm  16 . The rod and cylinder ends are pivoted by means of pivot pins  88  extending through the apertured side frames  32  and the apertured extensions  36 . Each pivotal connection also includes a journal fitting  90  located between the side frames  32  and the extensions  36 . Outboard locking lobes  92  are affixed to the ends of lower pin  88 , and are secured by bolts  94 .  
         [0029]     Similarly, the second piston and cylinder assembly  86  is pivotally coupled between the extension  38  and bracket  62  of the jib arm  14 , with the rod end of the assembly  86  secured to the bracket  62 , and the cylinder end of the assembly coupled to the extensions  38 . To this end, pivot pins  96  extend through the reinforcement plates  42  and extensions  38 , and through the side plates  64  of the bracket  62 . Journal fittings  98  are located between the extensions  38  and side plates  64 . Each of the piston and cylinder assemblies  84 ,  86  is convention in nature and may be, for example, hydraulically actuated via hydraulic line inputs illustrated in the drawings, and in particular in  FIG. 1 .  
         [0030]     Extension of the first assembly  84  causes the lower arm  16  to pivot relative to the stationary base  12  about pivot pin  44  from a position substantially perpendicular to a longitudinal axis of the cylindrical mounting component  28  (see  FIG. 1 ) to a position substantially parallel with the axis of the cylindrical mounting component  28  (see  FIG. 4 ). Conversely, retraction of the first assembly  84  causes the lower arm  16  to pivot relative to the stationary base  12  about the pivot pin  44  from the position substantially parallel with the axis of the cylindrical mounting component  28  to the position substantially perpendicular to the axis. It will be appreciated that the first assembly  84  may selectively assume any position from a fully retracted position to a fully extended position.  
         [0031]     Extension of the second assembly  86  causes the upper arm  18  to pivot relative to the lower arm  16  about pivot pin  76  from a position wherein the upper arm  18  and the lower arm  16  form an acute angle (see  FIG. 1 ) to a position wherein the upper arm  18  and the lower arm  16  form an obtuse angle (see  FIG. 7 ). Conversely, retraction of the second assembly  86  causes the upper arm  18  to pivot relative to the lower arm from the position wherein the upper arm  18  and the lower arm  16  from an obtuse angle to the position wherein the upper arm  18  and the lower arm  16  form an acute angle. It will be appreciated that the second assembly  86  may selectively assume any position from a fully retracted position to a fully extended position.  
         [0032]     The primary boom  22  is entirely conventional and may be an articulated “knuckle” boom or a multiple section extensible boom. The boom  22  carries at its upper end a conventional bucket leveling device  100  which is secured to the personnel bucket  24  and serves to maintain the bucket level during all movement of the boom. The device  100  includes an upper mounting surface  102  with an downwardly extending socket (not shown). This socket is designed to receive the component  28  of jib unit  10 , with the locking pin  30  extending thought the socket-defining body of the device  100  and through one of the locking holes  31 , to detachably mount the jib unit  10  to boom  22 . Note that the unit may be mounted in two positions relative to bucket  24 , by selection of an appropriate mounting hole  31 . Furthermore, the locking pin  30  is hand-removable, thus enabling a user to quickly and easily rotate the unit  10  relative to the personnel bucket  24  by withdrawing the locking pin  30  from the cylindrical mounting component  28 , rotating the unit  10  until the mounting holes  31  are in registry with corresponding mounting holes of the socket (not shown), and inserting the locking pin  30  to lock the unit  10  into the desired position.  
         [0033]     The personnel bucket  24  is designed to hold a worker and allow the worker to manipulate both primary boom  22  and jib unit  10 . Accordingly, as best seen in  FIG. 3 , operator controls  104  for the boom  22  are mounted adjacent the inner sidewall of the bucket. Additionally, a supplemental housing  106  is attached to the sidewall of bucket  24 , with the housing  106  having controls  108  for the jib unit  10 . The controls  104  and  108  are conventional controls that may include, for example, joy-stick levers or similar hand-actuated levers or buttons. Furthermore, the controls  104  and  108  may be purely mechanical controls, may be electronic in nature, or may include a combination of mechanical and electronic elements.  
         [0034]     In the embodiment illustrated in  FIGS. 1-5  and  7 - 8 , the pulley unit  72  is mounted on the outboard end of extension  66 . Also, nylon rope  110  is wound about reel  60  with the free end of the rope trained about pulley unit  72 .  
         [0035]     When the jib unit  10  is not in use, it may be conveniently placed in a stowed position illustrated in  FIGS. 1-3 . In this orientation, the assembly  20  is operated so as to retract both of the piston rods  84   b ,  86   b , and the extension  66  is moved to its retracted position. This involves detachment of positioning pin  56  and manual retraction of the extension  66  until the positioning aperture  70  comes into alignment with the pin aperture  57 . At this point, the pin  56  is reinserted to lock the extension  66  in its retracted position.  
         [0036]     When it is desired to use the jib unit  10 , the above procedure is reversed, i.e, the locking pin  57  is removed, extension  66  is manually shifted outwardly until aperture  68  comes into registry with aperture  57 , and pin  56  is reinserted. At this point, the user may manipulated the controls  108  in order to move jib arm  14  to desired work locations. The opposite ends of the range of movement of arm  14  are shown in  FIGS. 4 and 5 . A typical load-lifting position is illustrated in  FIG. 7 , allowing the user to lift loads up to a convenient height relative to bucket  24 .  FIG. 6  depicts a situation where the jib unit  10  is used to elevate phase lines during work around such lines. In this instance, a known phase lifter device  112  is attached to the outer end of extension  66  in lieu of the pulley unit  72 .  
         [0037]     If desired, a load chart can be displayed adjacent the controls  108  to assist the user, with this display having only one value per jib unit position, based upon the position of the jib arm  14  and the boom angle. Such a single-value load chart eliminates the need for the user to interpolate between multiple charts based on angle, position, or distance of boom and jib components, and load line. Moreover, an electronic version would gather input from angle sensing accelerometers positioned on the lower and upper arms of the jib arm  14 , and on the boom  22 . A jib sensor could also be attached to the jib arm  14  to determine the length of the jib in use. Based upon a combination of these inputs, a single allowable load could be displayed to the user.  
         [0038]     The jib unit  10 , making use of a doubly articulated assembly  20 , provides a working envelope significantly greater than that possible with only a single articulating design. Moreover, the jib unit  10  does not require pinning, unpinning, and repinning to achieve its maximum envelope of usage, as is common with singly articulating, extendable jib unit designs.