Abstract:
A crane is disclosed, with one or more moveable components. Manually-articulable controls (such as joysticks) are provided for controlling movement of the components. First, second, and third control circuits responsive to varied positions of the control are optionally connected to the control to provide first, second, and third sets of control signals each with differing responses to the control in a given position so as to move the components in a manner which mitigates instability or inaccuracy due to the physical acuity of the operator.

Description:
TECHNICAL FIELD 
     The present invention relates generally to cranes, and more particularly to circuitry and apparatus which are manually variable for controlling moveable components of the crane, such as booms, lift frames, winches, trolleys, hydraulic cylinders, hydraulic motors, valves, and wheels which move the cranes. 
     BACKGROUND OF THE INVENTION 
     Cranes, such as gantry cranes are used for lifting and handling loads. In particular, gantry cranes are used to lift such as truck trailers, cargo containers, boats and the like. The cranes normally have a gantry structure that spans over the load(s). For example, in intermodal applications, the crane may span over two adjacent railroad cars, a truck trailer adjacent a railroad car or side-by-side stacks of containers. Gantry cranes are frequently self-mobile, moving on tracks or wheels. 
     Conventionally, some sort of apparatus, such as a lift frame or a lifting yoke, is suspended from the gantry structure to engage and lift loads. Such apparatus must be moveable at least up and down. For intermodal applications the apparatus is also preferably moveable side-to-side and may be tilted end-to-end and side-to-side. 
     Movement of the crane itself and its moving components is generally accomplished directly, or indirectly, by the operator using control circuitry and apparatus which is manually-actuated and articulated to achieve desired variable speeds and directions. Controls, such as, joysticks, manually-rotatable wheels or roller balls, foot pedals and the like are moved and positioned by an operator. The movement and position are translated into a control signal to move and position a given component of the crane itself. 
     These controls must provide a wide range of control. For example, to engage loads and to maneuver in limited spaces, the controls must provide for slow and careful movement of the crane and its components. On the other hand, because of the high duty cycles required for efficient commercial operations, the controls must also provide for higher speeds when such precision of movement is not required. Also, for speed and efficiency of operation, an operator must be able to quickly and continuously vary the speeds from low to high and any appropriate speeds in-between. 
     Accordingly, conventional control systems provide manual controls permitting a continuous range of vehicle and component movement speed from a minimum to maximum speed which is relatively broad. Thus, accuracy and consistency of speed and direction affected by the manual controls on the vehicle or a given component is a function of the physical acuity of the operator attempting to physically position the control appropriately between its maximum and minimum value. 
     This poses a problem during operations which require a great deal of very precise, or slow, movement such as encountered by operators when positioning the crane or its lifting apparatus for proper engagement with, or over, a load. 
     For example, when using a conventional joystick to control the crane or its other moveable components, the operator can repeatedly overshoot, or undershoot, the position desired to properly align a lifting apparatus over the load. This is particularly problematic when twist locks are involved where all four corners of a lifting apparatus must be aligned with all four upper comers of a container to be lifted. Using the mechanical range and variable response of a conventional joystick to properly align the twist locks can be difficult and time consuming. 
     Another example of an operation which requires precision of speed and direction of movement is found in marine applications where the crane wheels must be directed on narrow sea walls in order to position the crane over a boat in the water. Such sea walls are frequently not much wider than the wheels of the crane and a small control error by the operator could be disastrous. 
     The present invention is proposed to solve these problems and to provide other advantages not provided in the same manner by conventional apparatus. 
     SUMMARY OF THE INVENTION 
     The present invention provides a control apparatus which changes the response of a moveable component of a gantry crane or the gantry crane itself, to a manually-articulable control when more precision of movement is desired. More particularly, a means is provided for changing the response to a given manual control when the means is activated. The means may either scale the range of response or provide a single constant output in response to manual activation. 
     In one embodiment of the invention, electronic circuitry, in the form of first and second control circuits, is used to control the rate, amount or direction of movement of the component or components. A manually-articulable control is provided which has a physical, mechanical range of movement. The manually-articulable control can be switched between the first and the second control circuits. 
     When connected to the first control circuit, a first range of control signals is generated in response to the manually-articulable control, the value of the signal corresponding to the mechanical range of manipulation of the control. Thus, when the first circuit is connected to the manually-articulable control, the control signal is dependent upon, and proportional to, a crane operator&#39;s manual articulation over the entire mechanical range of manipulation of the control. Accordingly, the rate and amount of movement of the moveable component are proportional to the crane operator&#39;s manual input over the mechanical range of manipulation of the manually-articulable control between a maximum and a minimum speed or amount of response. 
     When the manually-articulable control is connected to the second control circuit, a preset control signal is produced in response to any motion or position of the manually-articulable control after actuation. Thus, regardless of the precision or steadiness of the operator&#39;s physical manipulation of the manually-articulable control, the movement of the component is at a constant speed. Alternatively, the second circuit could be separately controlled by a second control. 
     In another embodiment of the invention, when the manually-articulable control is connected to the second control circuit, a second range of control signals is produceable in response to manipulation of the manually-articulable control over its entire range of manipulation. The second range of control signals is scaled to be a fraction of the first range of control signals. In other words, over the entire range of mechanical manipulation of the manually-articulable control, the first control circuit will produce movement of the moveable component from a minimum speed to a maximum speed. On the other hand, over the entire range of physical manipulation of the manually-articulable control, the second control circuit will produce movement of the moveable component from the minimum speed only up to a fraction of the maximum speed provided by the first control circuit. 
     According to another aspect of the present invention, the second control circuit has a means for variably adjusting the scaling of the second range of control signals or adjusting the preset constant speed control signal. 
     According to another aspect of the invention, means are provided to permit the operator to select either a second range of control signals, or a single preset signal provided by second and third control circuits. 
     According to another aspect of the invention, conveniently operable and accessible means are provided for switching between the first and second circuits. 
     Other advantages and aspects of the present invention will become apparent upon reading the following description of the drawings and detailed description of a preferred embodiment of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a gantry crane having control circuitry according to the present invention; 
     FIG. 2 is a block diagram of an electro-hydraulic circuit having first and second control circuits according to the invention; 
     FIG. 3 is a schematic representation of a top view of a swiveling operator chair having an actuator connected thereto; 
     FIG. 4 is a schematic side view of a multipurpose joystick illustrating its different ranges; 
     FIG. 5 is a block diagram of another embodiment of the present invention showing electronic circuitry having first, second, and third control circuits; and, 
     FIG. 6 is a schematic representation of foot pedals for actuating alternate circuits. 
    
    
     DETAILED DESCRIPTION 
     While this invention is susceptible of embodiment in many different forms, there is shown in the drawings-and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated. 
     FIG. 1 discloses a gantry crane  10  comprising a plurality of stationary components, which form the gantry frame  12 , and a plurality of moveable components connected to the stationary components. While there are numerous moveable components on the gantry crane  10  (discussed in detail below), the components primarily used to ensure proper position for engagement of loads are wheels  14 ,  16 ,  18 ,  20  and a lift frame  22 . 
     Gantry Frame 
     The gantry frame  12  has four vertical columns,  24 , 26 , 28 , 30 . Columns  24  and  30  are connected by a lower sill beam  32  and an upper sill beam  34  to form a first side frame  40 . Columns  26  and  28  are similarly connected by a lower sill beam  36  and an upper sill beam  38  to form a second side frame  42 . The first and second side support frames  40 , 42  are interconnected by a main support beam  48  at end  50  of the gantry crane  10  and by trolley beams  44 ,  46 . The trolley beams  44  and  46  are preferably I-beams and are mounted on upper side beams  34 , 38 . A vertically moveable operator cab  52  is mounted on one side support frame of the gantry frame  12 . The gantry frame  12 , thus formed, is an open-ended boxlike structure sufficient to span over adjacent loads, such as two railcars or a railcar adjacent a truck trailer, -or merely single loads. The benefits of the present invention, however, can be realized with other structures. 
     The Moveable Components 
     FIG. 1 discloses wheels  14 ,  16 ,  18 ,  20 , which are each individually powered by a dedicated hydraulic motor to make the gantry crane  10  self-mobile. The gantry crane  10  could also be self-mobile by means of railroad-track wheels, link-belt-type tracks, or the like. 
     The lift frame  22  is moved side-to-side by pairs of trolleys  54 ,  56 . Lift cables  58 ,  60  provide for vertical lifting of the lift frame  22 . 
     A first end  66  of a lift frame body  62  is suspended from the trolleys  54  by the lift cables  58  by suitable reeving (not shown) coupled to the trolleys  54 . A second end  68  of the lift frame body  62  is suspended from the trolleys  56  by the lift cables  60  in a similar manner. Lift cables  58 , 60  extend from the reeving on the trolleys to first and second winches, respectively (not shown) which are mounted on the gantry frame  12  through suitable reeving for independent vertical movement of the ends  66  and  68  of lift frame  22 . The first and second winches are each individually powered by a dedicated hydraulic motor (not shown but further explained in connection with FIG.  2 ). The first and second ends  66 , 68  of the lift frame  62  are permitted to be raised and lowered independently of one another to properly position the lift frame  62  when the load to be lifted is seated at an angle relative to the gantry frame  12 . 
     Trolleys  54 , 56  move laterally on first and second trolley beams  44 , 46  via cables attached between the trolleys  54 , 56  and third and fourth winches (not shown). The third and fourth winches are each powered by a dedicated hydraulic motor (also not shown but further explained in collection with FIG.  2 ). The trolleys  54 , 56  move independently on the trolley beams  44 , 46  so as to provide parallel alignment of the lift frame body  62  with loads which are not parallel with side support frames  40 , 42 . 
     The lift frame  62  is equipped with moveable spreaders  70 , 72 . The spreader  70  has moveable arms  74 , 76  that depend from the lift frame body  62 . Arms  74 ,  76  have a pivotal pivot shoes  78 ,  80 . 
     Similarly, spreader  72  has moveable arms  82 , 84 . The arm  82  has a pivot shoe  86  and arm  84  has pivot shoe  88 . The pivot shoes  78 ,  80 ,  86 ,  88  may be pivotally rotated to engage under a load, such as a cargo container. 
     When it is desired or necessary to engage a load at its top, the arms  78 ,  80 ,  82 ,  84  can rotate upward, out of the way, and the load can be engaged by specialized twist locks  90  located on the lift frame  62  (only two of the four twist locks  90  are shown). 
     Lift frame body  62  can be extended or retracted longitudinally as necessary to space spreaders  70 ,  72  or twist locks  90  to adjust to various load lengths. The lift frame body  62  includes various hydraulic mechanisms such as hydraulic cylinders or motors to move the above-described moveable components, as is conventional. 
     The gantry crane  10  is also equipped with stabilizing apparatus  92  to prevent unwanted sway of the lift frame  62  within the gantry structure  12 . The stabilizing apparatus generally includes a horizontal stabilizing beam  94  with vertical guides  96 ,  98  to prevent longitudinal and lateral sway, i.e., pendulous motion of the lift frame  62 . The stabilizing beam  94  operatively connects the lift frame  62  to the gantry structure  12 . 
     The lift frame  62 , is pivotally connected to the stabilizing beam  94  by a gimbal  100 . First and second ends  94   a ,  94   b  of the stabilizing beam  94  are connected to the first and second vertical guides  96 ,  98  which are connected to the first and second side support frames  40 ,  42 , respectively. A more detailed explanation of the structure and operation of the stabilizing apparatus  92  can be found in U.S. patent application Ser. No. 08/377,427 filed Jan. 24, 1995, which is specifically incorporated herein by reference. 
     Control of the Moveable Components 
     The above-described moveable components are moved by way of hydraulics, and suitable hydraulic circuitry is provided for conducting the necessary hydraulic fluids. Both cylinders and hydraulic motors used for moving the components are controlled by hydraulic spool valves which regulate the flow of hydraulic fluid. The spool valves are controlled by stepper motors which are controlled by electric control circuits linked to manually-articulable controls as will now be described in general. 
     FIG. 2, schematically discloses a moveable component  102  (such as one of the wheels  14 ,  16 ,  18 ,  20 ) which is driven by a hydraulic motor  104 , and controlled by a hydraulic valve  106 . The hydraulic valve  106  is controlled by a stepper motor  108 . As is known in the art, the amount of hydraulic fluid permitted to be delivered to hydraulic motor  104 , by the hydraulic valve  106 , as well as the rate of fluid transfer, determines the amount the hydraulic motor  104  moves, and the speed at which it moves. Accordingly, this controls the amount which the moveable component  102  moves as well as its speed. The change in position of the moveable component  102  is based upon the length of time the hydraulic valve  106  is permitted to deliver hydraulic fluid to the hydraulic motor  104  times the rate at which hydraulic fluid is being delivered to the hydraulic motor  104  over that time. 
     Electronic circuitry comprising stepper motor  108 , a first control circuit  110 , an actuator  114 , and a manually-articulable joystick  116  is provided to control the amount and rate of hydraulic fluid through the hydraulic valve  106  to control at least one aspect of the movement of moveable component  102 . Thus, in general operating modes where a wide range of speeds, and movement are needed, the first control circuit  110  responds to the position of the joystick  116  to provide a control signal to the stepper motor  108 . It will be appreciated by those skilled in the art that a circuit, such as circuit  110 , can also provide independent control signals to more than one moving component in response to the position of the joystick  116 . For example, in many cranes with wide spans between wheels the Ackerman Steering Principal is applied to turn each wheel to a different steering angle to accomplish a given turn in response to a joystick or steering wheel so as to avoid undue stress or wear on the wheels or gantry frame. In a second mode of operation, where more precision control of the moveable component  102  is desired (also referred to herein as an “inching” mode), a second control circuit  112  is employable. In the inching mode, the operator engages actuator  114  to connect the second control circuit  112 . The second control circuit  112  then generates a control signal to the stepper motor  106  in response to the position of the joystick  116 , to control the moveable component  102 . 
     Thus, over the range of physical manipulation of the joystick  116 , the circuits  110  and  112  provide independent, first and second ranges of control signals for controlling the movement of component  102 . The first range of movement is from a minimum to a maximum desired speed and range of movement. The second range speed is scaled to a desired fraction of the first range between minimum and maximum values. Thus, at any position of the joystick  116  when engaged with the second control circuit  112 , the moveable component  102  will only move at that desired fraction of the speed it would have moved at that same position under control the first control circuit  110 . 
     In an alternate embodiment, the second control circuit  112  can be used to provide a single preset signal, causing a single preset rate of movement of the moveable component  102  when the joystick  116  is moved, or actuated. This rate is usually relatively slow so that the moveable component  102  can be “inched” into position, such as to properly align the gantry crane  10  or lift frame  22  over a load. In this mode, the length of time the operator engages the joystick  116  is determinative of the movement, not the relative position of the joystick after engagement. 
     It should be noted that the second control circuit  1   12  may include an adjustment component to adjust either the preset constant signal to a desired level or to adjust the range limits of the reduced response to the joystick  116 . 
     Also, the actuator  114  may be in the form of a manual switch such as a foot switch, a flip switch, or a particular zone of physical position of the manually-articulable control. Alternatively, two controls could be implemented. The first and second control circuits in this instance would each be responsive to first and second control, respectively. Additionally, the actuator  114  could be a cam switch on one of the first or second controls. Such actuators are exemplified by the embodiments below. 
     In a preferred embodiment, the actuator  114  is located inside the operator cab  52  (FIG.  1 ). Specifically, as shown in FIG. 3, a swiveling operator seat  118  is located inside the operator cab  52 . The actuator  114  is affixed to a foot rest  120  on the seat  118  so that as the operator seat  118  swivels, the actuator  114  travels with it. The actuator  114  shown in FIG. 3 is a normally-off-biased foot switch; however, as mentioned above, the actuator  114  can take on a variety of forms. An advantage of the foot switch  114  is that an operator may engage or actuate the second control circuit  112  for the moveable component  102  (or for other components) without taking his or her hands away from other hand controls such as joystick  116  located on the control pads of the chair  118  (other controls shown but not numbered). 
     In a preferred embodiment, a control hierarchy exists between the first control circuit  110  and the second control circuit  112 . The first joystick  116  has a neutral position where no signal is generated, and non-neutral positions which generate control signals in a first range dependent on the non-neutral position of the joystick  116 . The actuator  114  cannot actuate a second control, and therefore, the second control circuit  112  when the first control, i.e. joystick  116 , is in a non-neutral position. 
     FIG. 4 discloses a multifunction joystick  122  which can be used in place of joystick  116  and actuator  114 . The joystick  122  has a lever handle  124  which is capable of being positioned in a neutral range N, a fixed rate range F and a variable rate range V. The fixed rate range F may further include a forward fixed rate range F f  and a reverse fixed rate range F r . Likewise, the variable rate range V may include a forward variable rate range V f  and a reverse variable rate range V r . By placing the joystick handle  124  in the forward fixed rate range F f , a preset forward control signal will be generated for moving the moveable component at a desired constant forward speed. Similarly, by placing the joystick handle  124  in the reverse fixed rate range F r , a preset reverse control signal will be generated for moving the moveable component at a preset constant reverse speed. Placement of the joystick handle  124  in.the forward-variable rate range V f  or the reverse variable rate range V r  will produce signals which vary according to the position of the joystick lever  124  within the variable rate range V. 
     FIG. 5 discloses an alternate embodiment where a third control circuit  126  is employed with first and second control circuits  110 ,  112 . An alternate actuator  128  has three positions so that it is capable of actuating any of the first, second, or third circuits  110 ,  112 ,  126  depending upon its position. For example, the actuator  128  may include first and second foot pads  130 ,  132  as schematically shown in FIG.  6 . When neither the first nor second foot pads  130 ,  132  are depressed, the gantry crane  10  operates in standard operating mode. However, by depressing the first foot pad  130 , the second control circuit  112  is actuated to move the moveable component  102  at a preset desired constant speed. Releasing the first foot pad  130  deactuates the second control circuit  112  and returns control to the first control circuit  110 . Similarly, by depressing the second foot pad  132 , the third control circuit  126  is actuated to provide a scaled signal range to reduce the response of the moveable component  102  to a given manipulation of the joystick  116 . Again, by releasing the second foot pad  132 , the third control circuit  126  is deactuated and control is returned to the first control circuit  110 . 
     While the specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention and the scope of protection is only limited by the scope of the accompanying claims. For example, It is contemplated that a manually-articulable control can be any device which is dependant on the operator&#39;s physical acuity to position or time its operational effectiveness, such as: a joystick, like joystick  116 ; a spring-loaded button or foot pedal; a steering wheel; a computer mouse; or, any switch which is biased against operation without physical contact or time-dependant in effecting its operational function. It is also contemplated that devices of the present invention would be advantageous on other than gantry cranes, for example, for controlling moveable components of a mobile boom-type crane.