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FIELD OF THE INVENTION 
       [0001]    The present invention relates to an arrangement for securing an implement to a carrier mounted to lifting arms, particularly those of a front loader boom, where the implement and carrier can be fastened to each other by movable latch rods that can be moved between latched and unlatched positions either manually or by a remotely controlled motor. 
       BACKGROUND OF THE INVENTION 
       [0002]    A known type of latch arrangement for securing an implement to a carrier mounted to lifting arms of a boom comprises a rod arrangement mounted to the carrier for being shifted laterally between latched and unlatched positions, with the rod arrangement being spring biased to its latched position. The rod arrangement can be either manually or hydraulically moved to the unlatched position, where a secondary latch is engaged by partially rotating the rod by the action of a second spring. The rod arrangement can then be released with the rod arrangement remaining in an arrested unlatched position until an implement coupled to the carrier is rolled back so as to engage the latch rod arrangement causing it to rotate out of its arrested position thereby disengaging the secondary latch permitting the latch rod arrangement to be moved to its latched position by the biasing spring. Such a prior art securing arrangement is disclosed in U.S. Pat. No. 7,001,137. 
         [0003]    Another known type of latch arrangement includes a remotely operable latch rod arrangement which is biased toward a latched position and is selectively moveable to an unlocked position by an extensible and retractable hydraulic cylinder controlled by a solenoid operated valve which is controlled by a circuit including a latching control switch and a height control switch connected in series so that both must be closed to complete a circuit to the control valve so as to prevent unlatching if the height sensing switch senses a height above a preselected safe height for implement detachment. U.S. Pat. No. 7,467,918 discloses such a prior art latch rod control. 
         [0004]    One drawback associated with the patented designs is that a failure of the biasing mechanism when the implement is attached to the boom could result in the latch rod migrating to its unlatched position. Another drawback of the patented designs is that an operator may not be aware if the latching rod arrangement becomes jammed or the like resulting in a partially latched implement. Further, while hydraulic cylinders are effective devices for moving the latching rod arrangements to their unlatched positions, hydraulic fluid leakage is always a problem and the provision of hydraulic hoses and control valves often take up valuable space and require special design considerations resulting in increased cost. 
       SUMMARY OF THE INVENTION 
       [0005]    According the present invention, there is provided an improved remotely operated latching system for detachably connecting an implement to a carrier mounted to a lifting arm. 
         [0006]    An object of the invention is to provide a remotely operated latching system which is compact and reliable. 
         [0007]    A more specific object of the invention is to provide latching system including a latch rod arrangement which is extendable from a latched position to an unlatched position, with a secondary latch arrangement being provided for rotating the latch rod arrangement into an arrested position once the latch rod arrangement in its extended, unlatched position, with an actuator for extending the latch rod arrangement acting to aid rotation of the latch rod arrangement into its arrested position. 
         [0008]    These and other objects are accomplished by using a linear electric motor for operating the latching rod arrangement, with a microprocessor based digital electronic control for the motor including safety interlocks for preventing unlatching of the implement if the boom is not in a lowered position. The electronic control unit also includes a capability to monitor operating conditions and to apprise the operator of the operating condition, through the means of an LEDs, where a slowly flashing light indicates that the latch rod arrangement is being extended to establish an unlocked condition, a quickly flashing light indicates a jammed condition and full extension being indicated by a steady light. The motor control includes an operating switch which may be placed in a manual over-ride mode whereby the operator may cycle the motor to extend and retract the latch rod arrangement such as to use the latching sections of the rod arrangement to “chip” through frozen material, or the like, blocking the passage of the latching sections to the latching position. 
         [0009]    These and other objects of the invention will be understood by a reading of the ensuing description together with the appended drawings 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a right side elevational view of a loader boom having a rear end mounted to a support frame and a front end coupled to an implement carrier to which an implement is attached. 
           [0011]      FIG. 2  is a right rear perspective view of an implement carrier equipped with a remotely controlled latching mechanism constructed in accordance with the principles of the present invention and showing the latch rod arrangement in a latched condition for securing an implement to the carrier. 
           [0012]      FIG. 3  is a right front perspective view of the implement carrier and latching mechanism shown in  FIG. 2 . 
           [0013]      FIG. 4  is an enlarged left bottom perspective view of a right end region of the carrier of  FIG. 2  showing the mount and shield assembly for the electric motor. 
           [0014]      FIG. 5  is a top view of the linear electric motor showing its connection to the right end region of the operating rod assembly of the latch rod arrangement  FIG. 6  is a rear view of the carrier shown in  FIG. 2 , but showing the operating rod in an unlatched position. 
           [0015]      FIG. 7  is a left end view of the carrier shown in  FIG. 6 , but showing the lever arm in phantom so as to show the latch rod positioned in the upper region of the guide slot and the secondary latch rod positioned in a lower region of the guide slot. 
           [0016]      FIG. 8  is a view like  FIG. 6 , but showing the latch rod arrangement in an unlatched, arrested position. 
           [0017]      FIG. 9  is a left end view of the carrier shown in  FIG. 8 , but showing the lever arm in phantom so as to reveal the latch rod arrangement in a lower region of the guide slot and the secondary latch rod below the guide slot, and showing a lower region of the left loader boom arm in dashed lines together with carrier being shown in dashed lines in a rolled back condition wherein an upper surface of the boom arm is in contact with, and holds the latch rod arrangement in a non-arrested position in an upper region of the guide slot, with the secondary latch rod being positioned for re-entry into the guide slot. 
           [0018]      FIG. 10  is a perspective view of a left end region of the implement carrier shown in  FIG. 6 , but showing an alternate embodiment featuring a coil spring which acts in compression to resist movement of the latch rod arrangement from its latched position while at the same time acting in torsion to bias the operating rod towards the bottom of the guide slot arrangement. 
           [0019]      FIG. 11  is schematic of the electrical circuit embodying the microprocessor and sensors used for controlling operation of the electric linear motor and giving an operator visual indication of whether or not the latch rod arrangement is operating correctly. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0020]    Referring now to  FIG. 1 , there is shown a front end loader  10  equipped with an attachment in the form of a bucket  14 . However, it is to be understood that the present invention may be used with other loaders and/or attachments. 
         [0021]    The loader includes a boom  28  comprising left and right, transversely spaced, fore-and-aft extending arms (only right arm  30  being shown) disposed for extending along opposite sides of a tractor (not shown) and each having a rear end pivotally attached, as by a pin  32 , to an upper region of a respective one of a pair of upright masts  34 , the masts  34 , in turn, being fixed to respective upper regions of a pair of upright mounting frames  36  located on opposite sides of, and having lower regions fixed to a frame (not shown) of the tractor. The boom  28  further includes a cross tube (not visible) having opposite ends projecting through, and joining the arms  30  together at a location forwardly of the tractor, with caps  38  being mounted on outer faces of the arms  30  so in closing relationship to opposite open ends of the cross tube. 
         [0022]    Mounted between a lower region of each of the masts  34  and the associated boom arm  30  is an extensible and retractable boom lift cylinder  40  having its rod end coupled to the mast  34  and its barrel end coupled to the arm  30 . An implement carrier  42  is pivotally attached, as at pins  44  to lower front end regions of each of the boom arms  30 , the carrier  42 , in turn, including an upper cross member  46  received within downwardly opening receptacles (not visible) of transversely spaced hooks  48  (only one shown) fixed to an upper region of the a backside of the bucket  14 . The bucket  14  is detachably coupled to a bracket arrangement (not shown) provided on the backside of the bucket  14 , as is described below in further detail. Provided for pivoting the carrier  40  about a horizontal axis defined by the pins  44  are a pair of extensible and retractable bucket tilt cylinders  50  (only one shown), each of which form one link of a leveling linkage  52  coupled, as at a pin  54 , between an upper end of each mast  34  and the implement carrier  42 , with extension of the cylinders  44  effecting clockwise rotation of the carrier  42  and associated bucket  14  about the horizontal axis defined by the pins  44 , while retraction of the cylinders  50  effects counterclockwise rotation of the carrier, and, hence, effects roll back of the associated bucket  14 , such roll back operation being important in the operation of latching the bucket  14  to, and detaching the bucket from, the carrier  42 , as is described below in further detail. 
         [0023]    Referring now to  FIGS. 2 and 3 , it can be seen that the cross member  46  at the top of the carrier  42  has right and left end regions to which are attached right and left vertical plate assemblies. Specifically, the right vertical plate assembly includes a pair of transversely spaced outer and inner loader arm mounting plates  56  and  58 , respectively, having upper ends fixed to the right end region of the cross member  46 . Similarly, the left vertical plate assembly includes outer and inner loader arm mounting plates  60  and  62 , respectively, having upper ends fixed to the left end region of the cross member  46 . The right and left vertical plate assemblies  56 ,  58  and  60 ,  62  each have a fore-and-aft dimension that increases from top to bottom. While not required for carriers of smaller loaders, the carrier  42  further includes right and left, inner strengthening plates  64  and  66  also having upper ends joined to the cross member  46  and having lower ends that terminate forwardly of lower ends of the plates  56 - 62 . The bottoms of the plates  56 ,  58  and the right inner plate  64  are joined together by a right rear cross bar  68 , while lower front regions of the plates  56 ,  58  and  64  are joined together by a right front cross bar  70 . Extending between and fixed to the front and rear cross bars  68  and  70  at respective locations spaced outwardly from the inner plate  66  is an upwardly projecting locking bar receiving plate  72 . Similarly, the bottoms of the plates  60 ,  62  and  66  are joined together by a left rear cross bar  74  having an inner end joined to a bottom rear location of the plate  66 , and being welded within complementary notches provided in the lower edges of the plates  60 ,  62 , while a front cross bar  76  extends between and is joined to lower front regions of the plates  60 ,  62  and  66 . Extending between and fixed to the left rear and front cross bars  74  and  76 , at locations spaced outwardly from the left inner plate  66 , is an upwardly projecting locking bar receiving plate  78 . 
         [0024]    A right tilt linkage mounting hole arrangement includes a pair of horizontal, axially aligned holes (only hole  80  in the plate  58  being visible) provided at an upper region in the right plate assembly comprising the plates  56 ,  58 , while a left tilt linkage mounting hole arrangement includes a pair of horizontal, axially aligned holes (only hole  82  in plate  54  being visible) provided at a mid-height location of the plates  54 ,  56  in axial alignment with the holes  74 . Respectively fixed to outer and inner faces of the plates  56 ,  58  of the right plate assembly are a pair of short cylindrical tubes  84  that are arranged in axial alignment with the holes  70 . Likewise, a pair of short cylindrical tubes  86  are fixed to the inner and outer surfaces of the left plate assembly comprised by the inner and outer plates  54  and  56  so as to be in axial alignment with the holes  82 . Referring back to  FIG. 1 , it can be seen that a pin  88  is received in each of the aligned pairs of holes  80  and  82  and serve to fix one end of a link of the bucket tilt linkage  52  to the right pair of arm mounting plates  56 ,  58  of the carrier  42 . 
         [0025]    A right loader boom mounting hole arrangement includes a second pair of axially aligned holes (only hole  90  in plate  58  being visible) provided at lower rear locations of the plates  56  and  58 , and a left loader boom mounting hole arrangement includes a second pair of axially aligned holes (only hole  92  in plate  60  being visible) respectively provided at lower rear locations in the left pair of plates  60  and  62 . Fixed to outer and inner surfaces respectively of the right plate assembly, comprised of the pair of plates  56  and  58 , so as to be in axially alignment with each other and with the holes  90  are short cylindrical tubes  94 . Similarly, fixed to outer and inner surfaces respectively of the left plate assembly comprised of the pair of plates  60 ,  62  so as to be in axial alignment with each other and with the holes  92  are short cylindrical tubes  96 . When the carrier  42  is mounted to the loader boom  28 , the right pair of boom arm mounting plates  56 ,  58  and the left pair of boom arm mounting plates  60 ,  62  respectively straddle lower front regions of the right and left boom arms  30 , with the holes  90  and  92  respectively receiving the pins  44  (see  FIG. 1 ). 
         [0026]    Spaced below the pair of hooks  48  on the back side of the bucket  14  (see  FIG. 1 ) are right and left, rearwardly projecting mounting lugs (not visible) respectively located for being received between the right strengthening plate  64  and the right latch rod receiving plate  72 , and between the left strengthening plate  66  and the left latch rod receiving plate  78 . Referring now also to  FIG. 4 , it can be seen that a latch rod guide  100  is mounted to an inner surface of the right strengthening plate  64 , the guide  80  including a vertical portion  102  extending parallel to, and being spaced inwardly from the plate  64 , with the vertical portion containing a rod-receiving hole  104  disposed in horizontal axial alignment with rod-receiving holes  106  and  108 , respectively provided in the strengthening plate  64  and the rod-receiving plate  72 . On the left side of the carrier  42 , the loader arm mounting plates  60 ,  62 , the latch rod-receiving plate  78  and the strengthening plate  66  respectively contain axially aligned holes  110 ,  112 ,  114  and  116  that are in axial alignment with the holes  84 - 88  and define a latch assembly pivot axis, these holes being brought into alignment with bores in the mounting lugs (not visible) of the bucket  14  for receiving latch rod elements, described below, to secure the bucket  14  to the carrier  42 . 
         [0027]    The present invention relates to a remotely operable latching mechanism  120  including an actuator arrangement  122  and a latch rod arrangement  124 . 
         [0028]    Referring now also to  FIGS. 3 and 4 , it can be seen that the actuator arrangement  122  includes a motor mount and shield assembly  125  including a vertical motor mounting plate  126  tightly secured against a left face of the right strengthening plate  64  by a pair of bolt and nut assemblies  128 . As can best be seen in  FIG. 4 , the support plate  126  is received within, and is shaped complementary to and is welded to, a right end region of an inverted channel-shaped motor shield  130 , which projects leftward from the strengthening plate  64 . Joined to, and projecting leftward from, a left face of the support plate  126  is a motor mounting clevis defined by upper and lower flanges  132  and  134 , which are disposed in parallel relationship to a top  136  of the shield  130 , the top  136  being inclined downwardly from front to rear. A bolt stem  137  of a motor mounting bolt and nut assembly  138  projects downwardly through the shield top  116  and through the aligned holes provided in the upper and lower flanges  132  and  134  so as to define an upright motor mount pivot axis having a purpose explained below. 
         [0029]    Referring also to  FIG. 5 , it can be seen that a linear electric motor  140  comprises a sealed body  142  which is substantially rectangular in cross section. The electric motor  140  has a built in microprocessor (described in more detail below) which continuously monitors the performance of the motor and can be directly interfaced with programmable controllers. An example of a suitable electric motor are those included in the Electrak Pro Series marketed by Danaher Motion located in Radford, Va. Respectively located at front regions of right and left ends of the motor body  142  in approximate transverse alignment with each other are a mounting lug  144 , defined by a rod, and an extensible and retractable output shaft  146 . The mounting lug  144  contains an upright bore  148  in which the stem  137  of the bolt assembly  138  is received when the motor  140  is mounted beneath the top  136  of the motor shield  130 , as shown in  FIG. 3 , the mounting lug  144  then being received between the motor mount flanges  132  and  134 . 
         [0030]    Referring back to  FIGS. 2 and 3 , it can be seen that the latch rod arrangement  124  includes a horizontal, transverse operating rod assembly  150  including an intermediate coupling rod  152  having a right end loosely received within a left end of a tubular coupler  154  and connected thereto by a bolt and nut assembly  156  wherein the bolt stem is disposed crosswise relative to the motor mounting bolt stem  137 . The motor shaft  146  is loosely received in a right end of the coupler  154  and is connected thereto by a nut and bolt assembly  158  wherein the bolt stem is disposed parallel to the motor mounting bolt stem  137 . A left end region of the coupling rod  152  is tightly received within a right end region of an elongate tubular rod section  160  that is received in an opening  162  provided in the strengthening plate  66 , and in a guide slot arrangement comprising a pair of transversely aligned guide slots  164  respectively provided in the loader boom mounting plates  60  and  62 , with it being noted that slots similar to the slots  164  are provided in the plates  56  and  58  so that during manufacture the plates  56  and  58  are respectively interchangeable with the plates  60  and  62 . As can best be seen in  FIG. 3 , the left end of the tubular rod section  160  is welded within an opening provided between opposite ends of a flat lever arm  166  disposed perpendicular to the rod section  160 . A rod is bent to form a handle  168  having an inner end of a horizontal transverse end section fixed to a rear end of the lever arm  166 , and having an outer end joined to a rearwardly extending hand grip portion. 
         [0031]    The latch rod arrangement  124  further includes right and left latch rods  170  and  172 . The right latch rod  170  includes a mounting portion  174  at its left end which is disposed along a lower front portion of the right end region of the tubular rod section  160 , with a pair of nut and bolt assemblies  176  including bolt stems extending through aligned bores provided in the coupling rod  152  and tubular rod section  160  so as to secure the rod  152  within the section  160  while solidly clamping the latch rod mounting portion  174  to the operating rod assembly  150 . Extending parallel to, and being axially offset to, the latch rod mounting portion  174  is a latch rod latching portion  178 , which is joined to the mounting portion by an intermediate portion  180 . 
         [0032]    As can best be seen in  FIG. 3 , the left latch rod  172  includes a left end region which projects through a hole (not visible) provided in a forward end of the flat lever arm  166  and into a cylindrical tube  182  welded onto an outer surface of the arm  166 . A nut and bolt assembly  184  secures the latch rod  172  within the cylindrical tube  182 . 
         [0033]    When the latch rod arrangement  124  is in a latched position, as shown in  FIGS. 2 and 3 , the latching portion  178  of the right latch rod  170  extends beneath the motor body  142  ( FIG. 3 ) and is received in the axially aligned holes  104 ,  106  and  108  respectively provided in the rod guide bracket  100 , strengthening plate  64  and latch rod receptacle plate  72 . The left latch rod  172  is then received in the axially aligned holes  110 ,  112 ,  114  and  116  respectively provided in the left boom mounting plates  60  and  62 , the latch rod receiving plate  78  and the left strengthening plate  64 . 
         [0034]    Thus, the operating rod assembly  150  forms a leftward extension of the motor output shaft  146  and has a left end region projecting through the guide slot arrangement comprising the pair of transversely aligned guide slots  164  respectively provided in the left pair of plates  60  and  62 . The guide slots  164  are located approximately mid-way between the sets of holes  82  and  92 . As described above, the left latch rod  172  is fixed for movement with the operating rod  132  by the flat lever arm  166 . A secondary latch rod  186  has an outer end welded to a lower middle location of the lever arm  166  and, when the operating rod assembly  150  is in the latched position shown in  FIGS. 2 and 3 , the secondary latch rod projects upwardly to the right through a lower region of the guide slot  164  provided in the outer left plate  60 , with the lever arm  166  then being disposed in a raised position flat against the left surface of the plate  60 . The handle  166  is provided for manual operation of the operating rod assembly  150  in the event of a failure of the electric motor  140 . 
         [0035]    Movement of the latch rod arrangement  124  from its latched position shown in  FIGS. 2 and 3  to an extended unlatched position, shown in  FIG. 6 , is resisted by a coil compression spring  188  received on the operating rod assembly  150  at a region just to the right of the inner boom arm mounting plate  62  and having opposite ends engaged with right and left flat washers  190  and  192 , respectively, with rightward movement of the washer  190  being prevented by a nut and bolt assembly  194  including a bolt stem projecting through the tubular rod section  160 , and with leftward movement of the washer  192  being prevented by the plate  62 . As can be seen in  FIG. 6 , a coil tension spring  196  is coupled under tension with a hook at an upper end being engaged with a coil of the compression spring  188  and with a hook at a lower end being received within a hole provided in the strengthening plate  66 , the spring  196  acting to bias the tubular rod section  160  of the operating rod assembly  150  toward the bottom ends of the guide slots  164  for a reason described below. 
         [0036]    The secondary latch rod  186  is provided for retaining the operating rod assembly  150  in an arrested position, as shown in  FIGS. 8 and 9 , wherein the operating rod assembly  150  has been shifted to the left a sufficient distance to withdraw the secondary latch rod  186  from the guide slot  164 , thereby permitting the action of the tension spring  196  to rotate the operating rod assembly  150  about the latch rod axis into a bottom region of the guide slots  164 , resulting in the end of the secondary latch rod  186  becoming misaligned relative to the adjacent guide slot  164  so as to retain the operating rod assembly  150  in its extended, unlatched position. As can be seen in  FIGS. 7 and 8 , the extended motor output shaft  146  is misaligned relative to the axis of the operating rod assembly  150  which means that the motor housing  142  is rotated downwardly about the upright axis defined by the bolt and nut arrangement  138 , this downward rotation occurring gradually as the output shaft  146  extends with the result that the motor transfers a downward component of force to the operating rod assembly  150  that is added to that exerted by the tension spring  196  so as to aid in moving the operating tubular rod section  160  to the bottoms of the guide slots  164 . 
         [0037]    When the carrier  42  is rolled back, as shown in dashed lines in  FIG. 9 , it can be seen that the tubular rod section  160  of the operating rod assembly  150  comes into contact with a forward surface  197  of the left loader arm  30  and lifts the rod section to the top region of the guide slot  164 , with the secondary latch rod  186  then being realigned with the guide slot  164  so as to permit the operating rod assembly  150  to be retracted to its latched position. 
         [0038]    Referring now to  FIG. 10 , there is shown an alternate embodiment of the manner of effecting the latching of the secondary latch rod  186 . Specifically, the compression spring  188  of the first-described embodiment is replaced by a combined helically wound compression and torsion spring  188 ′, the latter having a straight left end section  198  that extends upwardly behind an abutment pin  200  that is fixed to, and projects to the right from, the plate  62  at a location adjacent an upper end of the adjacent guide slot  164 . A torsion adjustment nut  202  is secured to a right end of the spring  158 ′ and can be advanced toward the left along a threaded section (not shown) of the operating rod tube section  160  to cause an increase in the torsion pre-load of the spring  188 ′. Thus, the reaction of the force exerted by the spring end  198  on the abutment pin  200  is transferred through the spring to the tubular rod section  160  so as to urge the operating rod assembly  150  toward the bottoms of the guide slots  164 . Accordingly, the tension spring  196  used in the previously described embodiment is no longer needed. 
         [0039]    Starting with the implement carrier  42  mounted to the arms  30  of the loader boom  28 , an implement, such as the bucket  14  can be attached to the carrier  42  by positioning the carrier  42  so as to bring the cross member  46  into engagement with the downwardly opening receptacles of the mounting hooks  48  provided at the backside of the bucket  14 , and then by raising the bucket off the ground far enough that it pivots downwardly against the front of the carrier  42 . The transversely spaced pair of mounting lugs (not shown) at the backside of the bucket  14  will at this time be respectively in fore-and-aft alignment with the space between the right latch rod receiving plate  72  and the right strengthening plate  64 , and with the space between the left latch rod receiving plate  78  and the left strengthening plate  66 . The operator will then operate the bucket tilt cylinders  50  to cause the carrier  42  to roll back about its pivotal connections  44  of the carrier  42  with the boom arms  30 . This will cause the arrested operating rod assembly  150  to come into engagement with the front surface  197  of the left loader arm  30  and to be shifted towards the upper end region end of the guide slots  164 . At this point, the right end of the secondary latch rod  186  will come into register with the guide slot  164  in the plate  60 , while cross bores provided in the bucket mounting lugs will be in axial alignment with the holes respectively provided in the plates  64 ,  72  straddling the right bucket lug, and provided in the plates  66 ,  78  straddling the left bucket mounting lug. The motor  140  is then operated to cause it to retract thereby simultaneously moving the right latch rod portion  178  through the bore in the right bucket lug and then into the hole  108  provided in the latch rod receiving plate  72 , and moving the left latch rod  172  through the bore in the left bucket lug and then into the hole  116  provided in the left strengthening plate  66 . 
         [0040]    Referring now to  FIG. 11 , there is shown a schematic of an electrical control system  210  for remotely controlling the operation of the linear electric motor  140 . Specifically, the electric control system  210  includes an electrical control unit (ECU)  212  connected to the motor  140  by a motor activation output signal line  214 . The ECU  212  preferably, but not necessarily, is a microprocessor which is embodied in the electric motor  140  and continuously monitors the performance of the motor. For purposes indicated below, the motor  140  embodies an electronic load sensor  216  and end of stroke limit switches  218  (extend limit) and  220  (retract limit) here depicted as being respectively connected to the ECU by conductors  222 ,  194  and  196 . While not required, the end of stroke positions governed by the limit switches  218  and  220  could be programmable. 
         [0041]    A manually-operated control switch  228  for initiating activation of the motor  140  is located within the cab (not shown) of a tractor and is connected to the ECU  212  by a motor activation input line  230 . The control switch  228  may take various forms including: (1) a momentary “on” rocker switch, (2) a momentary “on” rocker switch with a 1 second delay, (3) a momentary “on” rocker switch with a ½ second delay and a ½ second release window trigger indicated by an LED, (4) a momentary “on” push button switch, (5) a momentary “on” push button switch with a recessed button, and (6) a momentary “on” push button switch with a recessed button with a ½ second delay and a ½ second release window trigger indicated by an LED. Also, instead of a single switch, two momentary toggle switches may be used, with each being toggled in opposite directions. A height sensor  232 , shown mounted on the right mast  34  in  FIG. 2 , is connected to the ECU  182  by a height signal input line  234  and is provided for preventing actuation of the electric motor  140  when the carrier  42  is above a predetermined height off the ground. The boom height sensor  234  detects the pivot angle of the lifting boom  28  about the horizontal axis defined by the coupling pins  32 , which secure the boom arms  30  to the masts  34 . The height sensor  234  may be, for example, a potentiometer or an incremental angle transmitter which transmits this signal to the ECU  212 . Angular regions are stored in memory in the ECU  212 , in which an activation of the motor  140  can be prevented at inappropriate positions of the lifting boom  28 , for example, if it is raised beyond a height considered to be an upper height limit for safe disconnection of an implement from the carrier  42  mounted to the boom arms  30 . The angular regions, in which a signal sent by the height sensor  232  is to be ignored, can be permanently programmed or provided as input by the operator with an input key  236  provided in the tractor cab (not shown) and connected to the ECU by an input signal line  238 . The input key  236  can also be used to program the aforementioned travel end limits of the motor output shaft  146 . 
         [0042]    An LED indicator  240  is provided for apprising an operator of the operating condition of the motor  140  and boom  28  as determined by the load sensor  216 , output shaft end limit sensors  218  and  220 , and height sensor  232 . The LED indicator  240  is coupled to the ECU  212  by an output signal line  242  for receiving operation condition signals from the ECU  212 . 
         [0043]    Remote operation of the latching mechanism  120  through remote actuation of the linear electric motor  140  is described below with reference to  FIGS. 1 ,  2  and  11 . Assuming the implement  14  to be latched to the carrier  42 , as shown in  FIG. 1 , and that the tractor  10  is properly located for depositing the implement  14  on the ground, operation to detach the implement  14  from the carrier is commenced by lowering the loader boom  28  so as to place the implement  14  close to the ground. The bucket tilt actuators  50  are then caused to retract to completely roll back the carrier  42  and associated implement, with the weight of the implement  14  thus being relieved from the latch rods  170  and  172 . The normally “off” switch  228  is then momentarily actuated to its “on” position so as to activate the motor  140  to cause extension of the motor shaft  146  and hence extension of the operating rod assembly  150 . Since the carrier  42  has been lowered, the height sensor  232  will not be activated and the signal sent by the switch  228  to the ECU  212  will result in an operating signal being sent to the motor  140  by way of the output line  214 . The motor  140  will then be activated to cause extension of the output shaft  146  and the operating rod assembly  150 . Assuming the latch rod  172  and the latch rod portion  178  are free to move so that no jamming occurs, extension of the latch rod assembly  150  will take place, causing the latch rod  170  and latch rod portion  178  to be fully pulled out of the associated left and right lugs (not shown) provided at the backside of the implement  14 . During extension of the motor output shaft  146 , the retract limit sensor  220  will initially be activated, then cease to be activated as the shaft moves away from its retract limit position, resulting in the LED indicator  212  receiving a signal causing it to blink slowly indicating continuous outward movement of the output shaft  146 . When the output shaft  146  reaches the extend limit position, limit sensor  218  will be activated, sending an input signal to the ECU  212  resulting in the LED indicator receiving a signal causing it to produce a steady light apprising the operator that the unlatch position has been achieved, with the secondary latch pin  186  then being withdrawn from the left guide slot  164 . The tension spring  196 , together with the motor  140 , which is now angled downwardly to the left, will then act to rotate the operating rod assembly  150  to the bottom end of the slots  164 , resulting in the secondary latch pin  186  becoming misaligned with the adjacent slot  164  so that the latch rod arrangement  124  is arrested in the unlatched position. The boom  28  can then be lowered to disengage the cross bar  46  from the hooks  48  at the backside of the implement  14 , thus permitting the tractor  10  to be backed away from the implement  14 . 
         [0044]    The implement  14  can once again be attached to the carrier  42  by a reverse operation. Specifically, the tractor  10  can be driven toward the backside of the implement  14  and the boom  28  and carrier  42  lowered so as to place the cross bar  46  beneath the downwardly opening hooks  48 . The boom  28  is then raised, with gravity causing the implement  14  to pivot downwardly about the axis of the cross bar  46  and rest against the carrier  42 , with left and right lugs at the backside of the implement  14  respectively being received between the right latch rod receiving plate  72  and right strengthening plate  64 , and between the left latch rod receiving plate  78  and the left strengthening plate  66 . To ensure axial alignment of the bores in the bucket lugs with the holes of the receiving plates  72 ,  78  and the strengthening plates  64 ,  66 , the tilt cylinders  50  are retracted to effect full roll back of the carrier  42  and associated implement  14 . Not only does this result in the desired bore and hole alignment mentioned above, but it also results in the tubular section  160  of the operating rod assembly  150  coming into engagement with the top surface of the left loader boom  30  and being lifted towards the top of the guide slots  164 , this lifting initially resulting in the right end of the secondary latch pin  186  entering the left guide slot  164 . The normally open, motor actuating switch  228  is then manually actuated to send a motor control signal to the ECU  212 . The ECU  212  will then send a motor activating signal causing the motor  140 , at one second intervals, to attempt to retract. If the motor  140  causes the right and left latch rods  170  and  172  to move more than 5 mm., then the motor retracts under full power and the LED indicator  232  blinks slowly. If either one or both of the latch rods  170  and  172  jam, then an overload condition is sensed by the overload sensor  216  which sends a jam signal to the ECU  212  resulting in an output signal being sent to the LED indicator  242  which causes the LED to blink rapidly, with power to the motor  140  via the line  214  being terminated, with the motor  140  going into a latch mode causing the output rod  160  to be retracted. If, instead of a jam occurring, the retract limit of the motor output shaft  146  is reached, the retract limit sensor  220  is activated resulting in the ECU  212  receiving a signal which is processed, the ECU  212  then terminating power to the LED indicator  240 , which shuts off, and with power simultaneously being cut to the motor  140 . 
         [0045]    If jamming happens during latching operation, the operator may use the input key  236  to send an override signal to the ECU  212 , which permits the motor control switch  228  to be intermittently switched “on” and “off” so that the motor  140  is intermittently energized so as to cause the output shaft  146  to extend and retract with the result that the latch rod portion  178  and latch rod  172  are moved back and forth so as to chip away at any material that may be causing an obstruction in the aligned holes provided on the carrier  42  and the lugs (not shown) at the backside of the implement  14 . Upon the material becoming dislodged, the input key  236  can be operated to send a signal to the ECU  212  for resumption of normal operation. 
         [0046]    Thus, it will be appreciated that the electric linear motor  140  makes it possible to remotely effect attachment and detachment of an implement  14  to and from arms  30  of a loader boom  28 , and that the boom height sensor  232  together with the ECU  212  prevents the operator from inadvertently unlatching the implement when the boom  28  is positioned in other than a safe lowered position, while the various motor operation sensors together with the ECU  212  and the LED indicator  240  inform the operator as to whether there is a jam preventing the motor  140  from effecting desired latching or unlatching operations. 
         [0047]    In the event of a failure of the linear electric motor  140 , the motor output shaft  146  can be disconnected from the operating rod assembly  150  by removing one or both of the nut and bolt assemblies  156  and  158 . Operation of the latch rod assembly  124  can then be performed manually. Movement of the operating rod assembly  150  to effect the unlatched arrested position can be accomplished by grasping the handle  168  and pulling outwardly on the operating rod assembly  150  against the bias of the spring  188  until the secondary latch rod  186  is pulled free of the guide slot  164  provided in the left plate  60 . The handle  168  may then be used to pivot the lever arm  166  downwardly so that the operating rod  132  moves to the bottom of the guide slots  164 , with the secondary latch rod  186  then being misaligned relative to the guide slot  164  so as to prevent rightward movement of the operating rod assembly  150  by the compressed spring  188 . The latch rod  172  and latch rod portion  178  are then in respective positions to the left of left and right lugs (not shown) provided at the backside of the implement  14  and disposed between the rod receiving plate  78  and strengthening plate  66 , and between the right receiving plate  72  and strengthening plate  64 . 
         [0048]    Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.

Summary:
A remotely operable latching system is provided for securing an implement to a carrier mounted to a forward end of a lifting arm for pivoting about a horizontal tilt axis. The latching system is mounted to the carrier and includes a latching rod arrangement operated by an extensible and retractable linear electric motor between a retracted latching position and an extended unlatching position. A secondary latch arrangement is provided for rotating the latching rod arrangement to an arrested position preventing movement of the rod arrangement to its latching position once the latching rod is extended to its unlatching position. Movement of the rod arrangement to its arrested position is aided by a spring and by the electric motor. Release of the rod arrangement from the arrested position is done by rolling the carrier back towards the lifting arms bringing the latching rod arrangement into contact with the arm so as to pivot the rod arrangement out of its arrested position. A microprocessor based control unit is coupled to the electric motor and acts in response to a boom height input signals to prevent operation of the motor when the boom is above a preset height. Further, an LED indicator light operates in certain modes which apprise the operator of various operating conditions. For example, the LED light blinks slowly when the latching rod arrangement is being extended to its unlatch position, blinks rapidly if the latching rod jams causing an overload condition and gives a steady light when the latching rod arrangement is fully extended. Various timing requirements are also programmed into the control unit.