Abstract:
The invention is a manually operable control wand for use with hydraulically actuated overhead personnel cranes or &#34;Cherry Pickers&#34;. The wand is fixedly secured to a personnel carrying enclosure and includes a pair of operating shafts operatively coupled together and to a mounting base. A plurality of electrical switches which effect operation of the hydraulic actuator means of the overhead personnel crane and mounted adjacent the operator levers in positions such that movement of the operating levers in positions such that movement of the operating levers in the direction of desired movement of the personnel enclosure produces the corresponding movement of the enclosure.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to hand operated controls for hydraulic devices and particularly to such a device used in conjunction with a hydraulic personnel lifting crane which provides maneuvering of the crane by means of a single operating handle and in which movement of the &#34;bucket&#34; carrying the person is effected by movement of the control handle in the direction of desired movement. 
     2. Description of the Prior Art 
     The mobile aerial tower comprises an elongated, articulated arm which can be extended by means of hydraulic cylinders and related linkages and which has a basket or &#34;bucket&#34; fixed to the distal end thereof for the purpose of elevating workers in such applications as the repair of telephone lines, picking fruit, fighting fires, and the like. Such devices have become known, and are commonly referred to as &#34;cherry pickers&#34;. Such devices are typically mounted on a vehicle such as a truck and provide a convenient and efficient apparatus which enables workers in various occupations to perform their functions in elevated locations. 
     The cherry picker is typically provided with a series of switches mounted adjacent the upper periphery of the personnel carrying bucket. These switches are, in turn, connected to one or more hydraulic valves which control the flow or hydraulic fluid to a plurality of cylinders which effect the raising, lowering, and similar movements of the bucket. This of course enables the operator to position himself conveniently to his work and to otherwise control his position while in the bucket. 
     However, the control switches provided in prior art cherry pickers have comprised a plurality of separate switches, there being a different switch for effecting control of elevation, a second switch for controlling right and left hand movement, and a third switch for effecting forward and reverse movement of the bucket and in some units, a fourth interlock switch for preventing inadvertant movement of the bucket. Reliance on the workers sense of feel is unreliable since the worker is typically wearing heavy work gloves. Accordingly, when utilizing such an arrangement of switches, it is frequently necessary for the operator to remove his eyes from his intended work object to observe the switches and insure that he has selected the proper switch to manipulate the bucket. In the alternative, it is possible for the operator to operate an incorrect one of the switches thereby effecting the movement of the bucket in an undesired direction. This can be not only inconvenient but, in the event that the worker is working adjacent dangerous objects such as high power lines, such inadvert movement can be highly dangerous. 
     SUMMARY OF THE INVENTION 
     The present invention has as its objective to provide a manually operated control handle or wand which is mounted adjacent the upper periphery of the personal carrying bucket and which produces the desired control signals for manipulation of the bucket by a corresponding movement of the wand in the direction of desired movement. Because control of the bucket is thus effected utilizing a single control, it is no longer necessary for operator to remove his eyes from his work object and, because movement of the wand in a particular direction results in corresponding movement of bucket in that direction, precise and predictable control of the bucket results. 
     In its broader aspects, the manually operated control wand includes an elongated handle portion which is mounted to a supporting base for movement in combinations of vertical and horizontal directions and including a slide mounting which enables forward and reverse movement of the wand. The proximal end of the wand assembly engages one or more of a plurality of switches in response to axial movement of the wand which effect movement of the bucket in the desired forward or reverse direction. The wand itself is spring biased to assume a neutral position if the absence of external force. 
     It is therefore an object of the invention to provide and inproved, manually operable switch assembly for use with an overhead personnel crane. 
     Another object of the invention is to provide such an apparatus which permits precise and predictable operation of the crane without visual observation of the operating apparatus. 
     Still another object of the invention is to provide such an operating device which effects movement of the personnel carrying bucket in the direction of movement of the operating wand. 
     Yet another object of the invention is to provide such a device which is simple and rugged in construction and reliable in operation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings wherein: 
     FIG. 1 is an axial sectional view of the operating wand in accordance with the present invention; 
     FIG. 2 is a side plan view of the apparatus; 
     FIG. 3 is a bottom plan view taken along section line 3--3 of FIG. 2; 
     FIG. 4 is a side plan view showing installation of the operating wand on a typical personnel carrying bucket of an overhead personnel crane; and 
     FIG. 5 is a shematic diagram showing the relationship of the wand switches and hydraulic system of a system utilizing the control of the present invention. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     Referring now to the drawings, there is shown in FIG. 1 a manually operable control wand for an overhead personnel crane shown in cross-section and denoted generally by numberal 10. The device comprises a mounting base or plate 12 of generally rectangular cross-section. A circular hole 14 is formed through the center of plate 12, hole 14 being provided with a tapered surface portion 16 at its upper (as viewed in FIG. 1) end 18. An elongated operating shaft 20, which includes an enlarged, spherical portion 22 adjacent its center is received with the spherical portion 22 in the tapered portion 16 of hole 14. 
     A retaining plate 24, is also provided with a central opening 26 and a tapered portion 28 which is received over the spherical portion 22 of shaft 20, recesses 18, 28 defining a socket. The plate 24 is secured by means of threaded fasteners 30 and secures the shaft 20 to the mounting plate 12 while permitting the shaft 20 to be swiveled or moved in any desired or horizontal (as viewed in FIG. 1) direction. 
     A collar 32 made of a rigid material is slidably secured to the outer surface 34 of shaft 20. Collar 32 includes an enlarged tapered flange 36 which abuttingly engages the upper surface 38 of retaining plate 24. 
     A lock ring 70 is fixedly engaged in a complementarly slot 72 provided in the outer surface 34 of shaft 22 about midway between the collar 32 and bottom 66 of handle 60. A compression spring 74 is disposed between the ring 70 and collar 32. 
     Shaft 20 is also provided with a reduced diameter portion 40 at its lower (as viewed in FIG. 1) end 42. A donut shaped collar 44 is fixedly secured to the shaft 20 about the reduced diameter portion 40 in a position with its upper surface 46 disposed in spaced-apart relationship to the under-surface 48 of mounting plate 12. Thus configured, it will be seen that when the shaft 20 is deflected, the flanged collar 32 will be urged upwardly and because of spring 74, will establish a lever force to automatically, in the absence of a deflecting force, cause the shaft to return to its normal centered position as shown in FIG. 1. 
     It can further be seen in reference to FIG. 1 that shaft 20 is hollow, having an internal bore 52 extending longitudinally therethrough. An internal shaft 54 is slidably received in the bore 52, as indicated by arrows 140. 
     The upper end 56 of shaft 54 is threaded at 56. The threaded portion 56 is in turn threadingly engaged with threaded bore 58 provided in a molded, generally cylindrical handle 60. The shaft 54 is further secured by means of lock nut 62 to prevent turning or other disengagement between the handle 60 and shaft 54. 
     Handle 60 is provided with an internal bore 64 extending partially therethrough from its lower (as viewed in FIG. 1) end 66. This bore is dimensioned to slidably engage the outer surface 34 of shaft 22. 
     Fixedly secured to the lower (as viewed in FIG. 1) end 78 of shaft 54 is an elongated retainer 80 of hexagonal cross-section. Ratainer 80 is secured by means of threads 87 therein and on the external surface of end 81 of shaft 54. Retainer 80 secures the collar 44 against a shoulder 83 formed on shaft 20. Retainer 80 has a hollow bore 85 extending from thread 87 to a reduced diameter hole 89 extending through the bottom wall 91 of the retainer 80. A pair of cupped spring retainers 93 are disposed at opposite ends of bore 85 and a compression spring 95 is compressed therebetween. Thus configured, it will be seen that the shaft 54 is normally maintained in a centralized or neutral portion but can be moved upwardly or downwardly in response to forces applied to handle 60. 
     An elongated cam shaft 82 is fixedly secured to and depends downwardly from the shaft 52, shaft 82 being secured by means of threads 87. Shaft 82 is provided at its lower end 84 with an enlarged cam portion 86. 
     The upper end of handle 60 is provided with a second cylindrical bore 90 in which is slidably received a push button 92 which extends outwardly from the upper end 94 of the handle 60. Push button 92 is of stepped diameter and is retained within the bore 90 by a flange 96 which abutingly engages the larger diameter portion 98 of push button 92. Push button 92 is further urged into its upwardly extended position (shown in FIG. 1) by a compression spring 100 which is compressably received between the lower surface 102 of push button 92 and a switch plate 104. An electrical contact is fixedly received in the bottom 97 of the push button 92, contact 106 effecting electrical contact between electrical terminals 108, 110 and switch plate 104, when the push button 92 is depressed as by an operators thumb. 
     A group of four momentary contact switches 112, 114, 116, and 118 are fixedly secured to the bottom surface of a switch mounting plate 120, the latter being secured to the under surface of mounting plate 12. The switches are arranged with their actuating buttons 122 disposed in closely spaced-apart relationship to the outer periphery of collar 44. Thus configured, it will be seen that when the handle 60 is deflected, resulting in corresponding deflection of the shaft 54, collar 44 will engage and thereby actuate one or adjacent pairs of switches 112, 114, 116, or 118. Specifically, movement of the handle which produces movement as indicated by arrows 124, or 126 will effect actuation of either switch 118 or 114, respectively. Similarly, movement in the direction of the arrows 128 or 130 will effect operation of switches 112 or 116 respectively. Movement of the collar in the direction of arrows 132, 134, 136, or 138 will result in actuation of respective pairs of switches 118, 112, 112, 114, 114, and 116, or 116 and 118, respectively. 
     A pair of switches 152, 154 (shown in FIG. 2 only) are fixedly mounted by means of a mounting plate 156 to the shaft retainer 80 with their actuating levers 160, 162 respectively disposed above and below the cam portion 86. Correspondingly, movement of the cam portion in the directions of arrow 140 will result in actuation of switch 152 or switch 154. 
     Referring now to FIG. 5, there shown in schematic form the connection of the switches 104, 112 through 118, and 152, 154 to the hydraulic control system of an overhead personnel crane. 
     The entire assembly 10 is mounted adjacent the upper periphery 180 of a personnel carrying bucket 182 in a position wherein the handle 60 can be easily grasped and manupulated by an operator 184. With the switches connected as shown in FIG. 5, it will now be seen that movement of the handle in an upward direction will result in upward movement of the bucket. Similarly, downward movement, right or left hand movement, or angular movement of the handle 60 will result in corresponding movement of the bucket 182. To prevent inadvertant operation or movement of the bucket 182, push botton 92 provides an interlock which prevents any signal from being transmitted from the switches 112 through 118 or 152, 154 to the hydraulic control system unless the button is depressed by the operators thumb. 
     All of the switches are received inside of a protective enclosure 186. Shaft 22 is enclosed by an accordion folded boot 188 to protect all of the components against dirt, damage, or other environmental factors. 
     In view of the above description, it will now be seen that the operating handle of the present invention provides an exceptionly convenient and predictable means for controlling movement of the personnel bucket 182. All movement occurs in exactly the same direction as movement of the operating handle. Bacause this movement corresponds to the normal movement of the operators hand, and because there is only one operating handle that must be manipulated, it is not necessary for the operator 184 to remove his eyes from his destination or work object thereby insuring more accurate positioning of the bucket 182. Further, since all of the movement results from a single operating handle responding to normal movement of the hand of the direction of desired movement, inadvertant movement of the bucket in an undesired direction cannot result by reason of the operator engaging or otherwise actuating an incorrect one of a plurality of buttons. This is particularly true when operators wearing work gloves, typically the case, which would interfer with his sense of touch. The structure is rugged and relatively fail safe, and does not add significantly to the cost of an overhead personnel crane while significantly enhancing the operating convenience thereof. 
     While there have been described above the principles of this invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of the invention.