Patent Publication Number: US-7905297-B2

Title: Automatic connection for mid-mounted implement

Description:
FIELD OF THE INVENTION 
     This invention relates generally to tractors and utility vehicles used for agricultural work and lawn care, and particularly to attaching implements to such tractors or vehicles. More specifically, the invention relates to an automatic connection mechanism for a mid-mounted implement such as a mower deck. 
     BACKGROUND OF THE INVENTION 
     Tractors and utility vehicles used for agricultural work and lawn care may carry a mid-mounted implement such as a mower deck that covers two or more rotary cutting blades on the lower ends of vertically oriented spindles. The implement may be attached to a tractor or other vehicle with mechanical linkages that allow the implement to be carried at a range of different heights, and raised or lowered between each height. Suspension devices may provide a parallelogram linkage arrangement between the front and back portions of the implement and vehicle to assure that as the implement is raised or lowered, the sides, front and rear of the implement are lowered or raised equally. For example, U.S. Pat. Nos. 5,025,617 and 6,584,756 relate to parallelogram lift linkages for mid-mounted implements. 
     Mower decks, snow blowers, and similar implements are not utilized full time with a tractor, so it is desirable that a suspension mechanism allow quick, easy removal and reinstallation of the implement. A mid-mounted implement also must be carefully positioned under the tractor at a specified location where the implement may be connected to the lift system linkage and PTO coupling members. Various mounting points in the lift system linkage must be aligned, and a tractor PTO shaft may be connected and secured to a propeller shaft on the implement using PTO coupling members. 
     Connecting a mid-mounted implement may be difficult due at least in part to the weight of the implement and connection points of the lift system that must be aligned. Additional effort may be required to secure PTO coupling members together. Removing a mid-mounted implement from under a tractor also may be difficult for the same reasons. 
     An automatic connection mechanism is needed for an implement that can be quickly and easily connected and disconnected under a tractor. A PTO coupling is needed that can reduce the difficulty of securing a tractor PTO to a propeller shaft on the implement. 
     SUMMARY OF THE INVENTION 
     The invention provides an automatic connection mechanism for a mid-mounted implement to a tractor. The rear lift linkage includes a pair of rear draft links pivotably connected to a tractor frame. Each rear draft link automatically and releasably engages the rear of the mid-mounted implement. The forward lift linkage is pivotably connected to the front end of the implement, and automatically and releasably engages forward end of the tractor frame. Additionally, a PTO coupling is provided that can automatically and releasably engage a tractor PTO to a propeller shaft on an implement. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a tractor frame with an automatic connection mechanism for a mid-mounted implement according to a first embodiment of the invention. 
         FIG. 2  is a perspective view of front and rear linkages of an automatic connection mechanism for a mid-mounted implement according to a first embodiment. 
         FIG. 3  is a perspective view of a PTO coupling of an automatic connection mechanism for a mid-mounted implement in a first embodiment of the invention. 
         FIG. 4  is a perspective view of a mid-mounted implement with an automatic connection mechanism according to a first embodiment of the invention. 
         FIG. 5  is a perspective view of a mid-mounted implement with an automatic connection mechanism according to a second embodiment of the invention. 
         FIG. 6  is a perspective view of a rear linkage of an automatic connection mechanism for a mid-mounted implement according to a second embodiment. 
         FIG. 7  is a perspective view of a PTO coupling according to one embodiment of the invention. 
         FIG. 8  is a cross section view of a PTO coupling in the first embodiment. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In one embodiment shown in  FIG. 1 , a mid-mounted implement is shown as mower deck  100  covering a plurality of rotary cutting blades, and preferably three cutting blades, on the lower ends of vertically oriented spindles. Alternatively, the mid-mounted mower deck may cover two cutting blades, or more than three cutting blades. The mid-mounted implement may have a top panel  102 , and downward extending edges  104  on its front, rear, left and right sides. The implement may have a total width greater than the track width of at least one set of wheels of tractor  105 , and is shown positioned under tractor frame  107  between front wheels  106  and rear wheels  108 . While a tractor drives over the implement, each front wheel may be supported by plate  109  mounted on the top surface of the implement. 
     In one embodiment, mid-mounted implement  100  may have gauge wheels  110  mounted adjacent the front edge of the implement, and gauge wheels  112  mounted adjacent the rear edge of the implement. In a cutting position, as shown in  FIG. 1 , the mower deck may be at least partially supported by the gauge wheels at various heights, and/or the gauge wheels may be positioned to avoid or reduce scalping of turf by the mower blades. In a drive over position, the gauge wheels may be retracted sufficiently so that the implement rests on the ground surface and is not supported by the gauge wheels. 
     In the embodiment shown in  FIGS. 1 and 2 , the automatic connection mechanism includes rear lift linkage  114  and forward lift linkage  116 , each linkage operating independently of the other. The rear lift linkage can support the rear of the implement at two separate points at or near the rear of the implement, and the front lift linkage can support the front of the implement at or near its front end. The pair of lift linkages together provide a four point parallelogram lift arrangement. Using the pair of lift linkages, a mid-mounted implement may be automatically and releasably connected to tractor  105  after the implement is straddled between the tractor&#39;s front and rear wheels, and preferably after the tractor&#39;s front wheels drive over the implement. After the implement is positioned between the front and rear wheels, the tractor may continue to drive forward so that the front and rear lift linkages automatically connect the implement to the tractor. 
     In one embodiment, rear lift linkage  114  may be pivotably attached to tractor frame  107 . Rear lift linkage  114  may include left and right rear draft links or arms  118 . The first or forward ends of rear draft links  118  may be pivotably attached to the tractor frame  107  or tractor body between the tractor&#39;s front and rear wheels. In the embodiment shown in  FIG. 2 , the first or forward ends of the rear draft links are pivotably attached to left and right rear support brackets  120 , which are attached to the tractor frame or body. Each rear draft link  118  may include a forward facing slot  122  at or adjacent the second or rear end of the rear draft link. Additionally, rear link rod  124  may connect together left and right rear draft links  118  at or adjacent their second or rear ends. Rear link rod  124  may be suspended by left and right rear hangers  132  which are pivotably attached to left and right rear lift support straps  134 . The rear lift support straps are connected to mid rock shaft  136  that is pivotably mounted in bearing blocks  138  secured to tractor frame  107 . 
     In one embodiment, rear lift linkage  114  can automatically and releasably engage two separate attachment members at or near the rear edge of the implement. For example, as shown in  FIG. 4 , the attachment members at the rear of the implement may be a pair of rear implement lift rods  126 , which may be wire forms. As the tractor moves forward, the left and right rear implement lift rods  126  can enter slots  122  in rear draft links  118 . Once rear implement lift rods  126  fully enter slots  122 , the lift rods may be automatically and releasably held in the slots by rear lock plates  128 . The rear lock plates may pivot on pins  129  to ride over and secure the implement lift rods in the slots. Rear lock plates  128  may be biased or urged by gravity to a closed or locked position. Left and right rear mounting plates  130  may provide guide surfaces to help direct rear draft links  118  laterally inwardly so that lift rods  126  are properly aligned to enter slots  122 . 
     In one embodiment, hydraulic lift cylinder  143  may be used to raise and lower rear lift linkage  114 . The hydraulic lift cylinder may be connected to bell crank  140  to assist in lifting or lowering the implement from the ground surface. Alternatively, a manually operated lever (not shown) may be connected to bell crank for raising and lowering the implement. 
     In one embodiment, to adjust the height of the implement once it is lowered, bell crank  140  is provided between mid rock shaft  136  and the rear end of height lock link  142 . A first or front end of height lock link  142  is pivotably connected to height lock lever  144 . Height lock lever pivots inside sector  146  mounted to one of rear support brackets  120 . Stop  148  may be provided in the other of rear support brackets  120  to limit pivotal motion of the first or forward end of the rear draft links  118 . To adjust the cutting height of mid-mounted implement  100 , the operator may pivot height lock lever  144  to extend or retract height lock link  142 , which pivots bell crank  140  to provide a lower stop for the implement once the lift cylinder or manual lever releases the implement. 
     In one embodiment, a first PTO coupling member is attached to PTO shaft  159  from the tractor. The first PTO coupling member may be mounted to the rear lift linkage so that it is properly aligned to automatically and releasably engage a second PTO coupling member attached to the implement. For example, in a preferred embodiment, the first PTO coupling member may be female PTO coupling member  152  mounted to rear lift linkage  114 , as shown in more detail in  FIGS. 2 and 3 . The second PTO coupling member may be male PTO coupling member  168  on the implement. Alternatively, the male PTO coupling member may be mounted on the rear lift linkage and the female PTO coupling member may be on the implement. 
     In one embodiment, during automatic connection of the mid-mounted implement, the first or female PTO coupling member  152  automatically and releasably engages the second or male PTO coupling member  168 . The first or female PTO coupling member may be rotatably mounted in bearing housing or carrier  154 . The bearing housing or carrier is supported by coupler support  156 . Coupler support  156  may be attached to a rear draft link  118  so that the coupler support, and the first PTO coupling member, can move or slide vertically with respect to the rear draft link. 
     In one embodiment, rear mounting plates  130  may guide rear draft links  118  laterally so that rear implement lift rods  126  enter slots  122  in the rear draft links. Rear mounting plates  130  also guide first PTO coupling member  152  attached to rear draft link  118 , into the correct engagement position laterally on the implement. Mounting the first PTO coupling member to the rear lift linkage places the first PTO coupling member in the correct position to engage the opposing second PTO coupling member on the mid-mounted implement. 
     In one embodiment, the second PTO coupling member may be on gearbox  166  on the top surface  102  of mid-mounted implement  100 . For example, the second PTO coupling member may be male PTO coupling member  168  attached to propeller shaft on gearbox  166 . Rear mounting plates  130  guide the rear draft links into alignment, and ensure that the male and female PTO coupling members are in the correct lateral position. Additionally, coupler alignment ramp  170  may be provided on the top surface  102  of the implement to ensure the male and female PTO coupling members are in the correct vertical position for engagement. Coupler alignment ramp  170  may be a sloped surface adjacent the rear edge of the implement. The female PTO coupling member  152  may slide or ride slightly upwardly on the coupler alignment ramp toward the same vertical position as male PTO coupling member  168  on the implement. 
     In one embodiment, the first PTO coupling member can move or slide vertically with respect to the rear lift linkage, and/or pivot on one or more axes. For example, female PTO coupling member  152  may be supported by coupler support  156 , which is attached to rear draft link  118  so that the female PTO coupling member can move vertically and/or pivot on one or more axes. More specifically, coupler support  156  and rear draft link  118  may be connected together using a bolt or rod and bushing  158  that slides vertically within slot  160 . Additionally, coupler support rod  162  may connect coupler support  156  to coupler support plate  164 . Coupler support plate  164  may be pivotably mounted adjacent a rear end of rear draft link  118 . 
     In one embodiment, female PTO coupling member  152  can automatically and releasably engage male PTO coupling member  168  as each coupling member is rotated to various different rotational positions. For example, the female PTO coupling member may be internally splined and the male PTO coupling member may be externally splined. Preferably, the female PTO coupling member has internal splines, and the male PTO coupling member has external splines. The splines provide surface-to-surface contact for rotational engagement. 
     Referring again to the embodiment shown in  FIG. 2 , the four bar parallelogram linkage includes forward lift linkage  116  that is pivotably mounted to mid-mounted implement  100 . The forward lift linkage may include left and right forward links  176 . Transverse rod  182  may be connected to the first or front ends of forward links  176 , connecting the forward links together. The second or rear ends of forward links  176  may include devises  178  for pivotably mounting using a pin to front mounting plates  180  at the front edge of the implement. Guide plates  184  may be provided at the front ends of forward links  176  to provide guide surfaces to help direct transverse rod  182  into slots  186  into a pair of transversely spaced apart and forward opening jaws or hook hangers  188  mounted to the forward end of tractor frame  107 . Additionally, spring  190  and rod  192  are connected between a forward link  176  and front mounting plate  180 , to urge the forward links into position where transverse rod  182  enters and remains in slots  186 . 
     In one embodiment, mid-mounted implement  100  may be quickly and automatically disengaged from tractor  105 . After the operator lowers the implement so that it rests on the ground surface, then the operator may pivot the lock plates  128  before backing up the tractor. The transverse rod  182  of the forward lift linkage automatically unhooks from hangers  188  near the front end of the tractor. Hangers  188  may be located in front of or behind the front wheels of the tractor. The operator also may pivot left and right rear lock plates  128  from the closed or locked position to an unlocked position. As the tractor continues to back up, the tractor completely disengages and separates the front and rear lift linkages, and the PTO coupling members. The rear lock plates automatically reset once the rear lift linkage is disengaged. 
       FIGS. 5-6  show a mid-mounted implement  200  that can be automatically connected to a tractor frame using a second embodiment. The second embodiment of the automatic connection mechanism includes rear linkage  214  and front linkage  216 . The mid-mounted implement may be a mower deck having top panel  202  and downward extending edges  204  on its front, rear, left and right sides. While a tractor drives over the implement, each front wheel may be supported by plate  209  mounted on the top surface of the implement. The implement  200  also may have gauge wheels  210  mounted adjacent the front edge of the implement, and gauge wheels  212  mounted adjacent the rear edge of the implement. In a cutting position, the implement may be at least partially supported by the gauge wheels, and/or the gauge wheels may be positioned to avoid or reduce scalping of turf by the mower blades. In a drive over position, the gauge wheels may be retracted so that the implement rests on the ground surface. 
     In a second embodiment, the mid-mounted implement may be automatically and releasably connected to a tractor after the implement is straddled between the tractor&#39;s front and rear wheels, and preferably after the tractor&#39;s front wheels drive over the implement. After the implement is between the front and rear wheels, the tractor may continue to move forward so that the lift linkages of the present invention automatically connect the implement to the tractor. 
     In a second embodiment, rear lift linkage  214  may be pivotably attached to the tractor frame. Rear lift linkage  214  may include left and right rear draft links or arms  218 . The first or forward ends  215  of rear draft links  218  may be pivotably attached to the tractor frame between the tractor&#39;s front and rear wheels. Rear link rod  224  may connect together left and right rear draft links  218  at or adjacent their second or rearward ends. 
     In a second embodiment, rear lift linkage  214  can automatically and releasably engage a pair of attachment members at the rear edge of the implement. For example, as shown in  FIG. 5 , the attachment members at the rear of the implement may be a pair of rear draft brackets  226  mounted on the implement. Each of the rear draft bracket includes a slot to capture rear link rod  224 . As the tractor moves forward over the implement, rear link rod  224  may enter the pair of rear draft brackets. Once the rear link rod fully enters the rear draft brackets, the rear link rod may be automatically and releasably held there by latches  228 . The latches may pivot on pins  229  to ride over and secure the rear link rod in the rear draft brackets. Latches  228  may be biased by spring  230  to an over center spring lock to a locked position. Additionally, latches  228  may be linked by rod  233  to allow simultaneously closing or releasing both latches. 
     In a second embodiment, the four bar parallelogram linkage may be raised and lowered using hydraulic lift cylinder  243 . Hydraulic lift cylinder  243  may be connected to bell crank  234 . Each rear draft bracket  218  may be suspended by left and right rear hangers  232  which are pivotably attached to left and right bell cranks  234 . The left and right bell cranks are connected to opposing ends of mid rock shaft  236  that is pivotably mounted in brackets  238  and/or bearing blocks secured to the tractor frame. Alternatively, a manually operated lever (not shown) may be connected to bell crank  234  for lifting and lowering the implement. Once the implement is lowered, the cutting height may be adjusted in a manner similar to that shown in the first embodiment. The height adjustment mechanism may provide a lower stop for the implement once the lift cylinder or manual lever releases the implement. 
     In a second embodiment, the automatic connection of a mid-mounted implement includes a first PTO coupling member attached to rear lift linkage  214 . Attaching the first PTO coupling member to the rear lift linkage provides proper alignment that is needed to automatically and releasably engage the first PTO coupling member with a second PTO coupling member on the implement. In a preferred embodiment, the first PTO coupling member may be female PTO coupling member  252  attached to rear lift link rod  224 , and the second PTO coupling member may be male PTO coupling member  268  mounted on the implement. 
     In a second embodiment, during automatic connection of the mid-mounted implement, the first or female PTO coupling member  252  automatically and releasably engages the second or male PTO coupling member  268 . The first or female PTO coupling member may be attached to PTO shaft  257 , and rotatably mounted in bearing housing or carrier  254 . The bearing housing or carrier is supported by coupler support  256 . Coupler support  256  may be attached to rear link rod  224  so that the coupler support, and PTO coupling member, may pivot on a horizontal axis of rear link rod  224 . As a result, the first PTO coupling member is in the correct position to engage an opposing second PTO coupling member on the mid-mounted implement. The opposing second PTO coupling member may be on gearbox  266  mounted on the top surface  202  of mid-mounted implement  200 . 
     In a second embodiment, female PTO coupling member  252  can automatically and releasably engage male PTO coupling member  268  as each coupling member is rotated to various different rotational positions. As in the first embodiment, the female and male coupling members may be splined. For example, male PTO coupling member may have external splines. Alternatively, the female coupling member may be provided on the implement gearbox, and the male coupling member may be connected to the rear lift linkage. 
     Referring still to the second embodiment shown in  FIGS. 5 and 6 , forward lift linkage  216  may be pivotably mounted to the front end of mid-mounted implement  200 . The forward lift linkage may be a U-shaped bar with left and right forward portions  276  and base portion  277  which loops around front mounting plates  280  at the front edge of the implement. A rod or abutment may hold the U-shaped bar in the front mounting plates. Transverse rod  282  may be connected to the first or front ends of forward links  276 . The transverse rod may be connected to the forward links with linkages allowing adjustment of the rod&#39;s position to engage a tractor&#39;s front hangers. Plate  292  may be fastened to the center portion of the forward lift linkage, and spring  290  may urge plate  292  to pivot the forward lift linkage up into position where transverse rod  282  enters and remains in the transversely spaced jaws or hooks at the front of the tractor frame. 
     In one embodiment, mid-mounted implement  200  may be quickly and easily disengaged from a tractor. To disengage the mid-mounted implement, the operator may simultaneously pivot left and right latches  228  to an unlocked position. The operator then may back up the tractor to automatically disengage transverse rod  282  from the hooks at the forward end of the tractor frame. As the tractor continues to back up, it completely disengages and separates the front and rear lift linkages, and the PTO coupling members. Rear latches  228  automatically reset after the rear lift linkage has disengaged. 
     In  FIGS. 7-8 , male PTO coupling member  301  is shown as a generally cylindrical outer body having first end  308  and second end  309 . The male PTO coupling member may have an internal bore  316  to facilitate mounting to an input shaft of a gearbox on a mower deck or other implement. A smaller first diameter  304  of the cylindrical outer body may be adjacent the first end, and a larger second diameter  306  is adjacent the second end. A step  310  may be provided between the smaller and larger diameters of the male PTO coupling member, and the step may be inclined. For example, the step may have dimensions of about 1.5 mm on radius, with an axial length of about 8 mm, and an angle of about 30 degrees. This step provides a circumferential gap as the male PTO coupling member is initially inserted into the female PTO coupling member. 
     In one embodiment, a pair of external splines  312 ,  314  may be provided on the cylindrical outer body of male PTO coupling member  301 , each of the splines separated by 180 degress. Spline  314  may extend axially along the cylindrical outer body of the male PTO coupling member between the first and second ends  308 ,  309 . Spline  312  may have a length about 5 mm to about 10 mm less than spline  314 , and may extend axially from a location about 5 mm to about 10 mm from the first end to the second end of the male PTO coupling member. 
     In one embodiment, each external spline  312 ,  314  may project radially outward about 6 to 10 mm from the cylindrical outer surface of the male PTO coupling member. Each external spline may have a width of about 5 mm to about 10 mm, and the leading edge of each spline may be beveled to a point  318  facing the first end of the male PTO coupling member. 
     In one embodiment, female PTO coupling member  302  may be a sleeve shaped body  321  having a first end  328  and a second end  329  connected to universal joint  326 . The first end of the female PTO coupling member may have a beveled leading edge  330 . Four internal splines  332  may be provided in bore  323  as it extends through the female PTO coupling member, each internal spline positioned 90 degrees from the adjacent internal splines. 
     In one embodiment, internal splines  332  may extend axially through internal bore  323  from first end  328  to second end  329  of the female PTO coupling member. Additionally, each internal spline  332  may be stepped to provide a narrowing clearance, or a stepped surface, in the internal bore for the male PTO coupling member. Adjacent the first end of the female PTO coupling member, a first length  337  of each internal spline may project radially inward about 3 to 5 mm from the internal bore of the female PTO coupling member. Adjacent the second end of the female PTO coupling member, a second length  339  of each internal spline may project radially inward about 6 to 10 mm from the internal bore of the female PTO coupling member. A step  336  may be provided between the first and second splined lengths. The step may be inclined, and may have dimensions of about 1.5 mm on radius, with an axial length of about 8 mm, and an angle of about 30 degrees. The steps on the female splines may be positioned and dimensioned to correspond to the steps on the outer cylindrical body of the male PTO coupling member. Each internal spline  332  in the female coupling member may have a width of about 5 mm to about 10 mm, and the leading edges of each spline may be beveled to a point  334 . 
     In one embodiment, the male and female PTO coupling members can be engaged by axially moving the members together. It is preferred that both PTO coupling members be axially aligned, but they can be engaged successfully even if their longitudinal axes are misaligned initially as much as about 10 degrees. When the male and female PTO coupling members move axially and come into contact, the beveled leading edge of the longer external spline of the male PTO coupling member may contact one of the female PTO coupling member&#39;s internal splines, or the beveled leading edge of the female PTO coupling member. While the PTO coupling members continue to be moved axially together, contact of the longer male spline with the female PTO coupling member causes one or both members to rotate and pivot sufficiently to reduce the axial and radial misalignment, and bring the PTO coupling members into closer alignment. For example, it is preferred that the initial alignment will result in a radial gap of about 2 mm to about 4 mm between the male and female PTO coupling members. This gap may be the actual difference in radial dimensions between the first end of the male PTO coupling member and the first end of the female PTO coupling member. Alternatively, one of the splines in the female PTO coupling member may be longer than the female PTO coupling&#39;s other internal splines. The longer spline in the female PTO coupling member may contact the male PTO coupling member first, and guide both PTO coupling members into alignment. 
     When the male PTO coupling member enters further into the female PTO coupling member, the first, smaller diameter end of the male PTO coupling member enters the second, smaller diameter end of the female PTO coupling member bore. The gap between these may be about 0.20 mm. Additionally, the second, larger diameter part of the male member enters the first, larger diameter bore of the female member, with a clearance of about 0.20 mm on radius. 
     During engagement of the male and female PTO coupling members, one of the splines is sufficiently longer than the other splines so that it initially contacts the opposing PTO coupling member before the other splines. This reduces or eliminates the tendency of splines to catch and hang up on opposing sides of the other PTO coupling member. 
     In an alternative embodiment, the female PTO coupling member may have six internal splines, each spline separated by 60 degrees from the adjacent splines. The male PTO coupling member may have two, three or four external splines to mate with the female PTO coupling member in the alternative embodiment. Preferably, the female member has at least as many splines as the male member. 
     Alternatively, a key coupler may engage the male to the female PTO coupling member, using keys in the female member that line up with slots in the male member. Alternatively, a dog coupler may be used, where limited key width allows for alignment without moving parts. 
     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.