Abstract:
A pick assembly for picking potatoes from a supply in a potato planter and moving them to a discharge position includes an arm that supports a plurality of picks that will engage the potatoes. The arm is mounted on a rotating wheel, and the picks are held in the arm with gently tapered bores in the arm and mating gently tapered conical surfaces on the pick that seat together when the pick is installed in the arm. The picks are maintained under axial compression loads to force the mating tapered surfaces together during use.

Description:
BACKGROUND OF THE INVENTION 
   A picker assembly that is used for picking individual pieces of material, such as seed potatoes from a hopper, and carrying them to a position where they are stripped off the individual picks or spears. As shown, the pieces are dropped through a suitable chute to a furrow being prepared by a planter. The picks or spears are carried on an arm and have conical outer surfaces that fit in matching conical bores and are locked in place by applying axial force to the picks. The picks are secured so they do not tend to work loose during use. 
   The pick assemblies for potato planters are well known and comprise a movable arm carrying the picks and a stationary arm. The arms are mounted on a rotating wheel and the movable arm carrying the picks will move from a position where the picks protrude through an opening in the stationary arm for engaging a seed potato, to a position where it retracts from the stationary arm and the stationary arm acts as a stripper to remove the potato. 
   In the prior art, rotating wheel potato planters have been well known, which include arms that carry picks, or spear-like sharpened columns or spears that will pierce or penetrate a potato as the wheel moves through a potato supply, with each arm picking up one seed potato and carrying it with the wheel in its path of rotation to a second position where the seed potato will be dropped. The arms that are used include a stationary arm, and a movable pick arm that supports the pick, with the pick protruding through an opening in the movable arm. As the arm set moves through the supply of seed potatoes, the pick pierces a seed potato. When the wheel on which the arms are mounted rotates to the position where the seed potato should be dropped for planting, the movable pick-carrying arm is retracted and the stationary arm of that set acts as a stripper to strip the seed potato from the pick. The movable pick arm then moves back to its position (as it enters the potato supply) with the picks protruding from the stationary arm as the arm set enters the seed potato supply so that the arm set will again pick up a seed potato, which usually is a section of a complete potato. 
   Various attempts have been made to maintain the picks securely held in the movable picker arm, but the picks continue to loosen and prematurely wear. For example, one prior pick was passed through a straight hole in the arm and it had a countersunk head held in position by a retainer bearing on the pick head with an axial force to seat the countersunk head. This arrangement failed to maintain the pick tightly in position during use. A straight cylindrical hole where the pick head is held down with a set screw that in turn is supported on a bar or cross member carried on the arm and passing over the pick has also been tried but has not proved satisfactory. Retainers of various kinds have been used, but generally they have failed to hold the pick tightly and securely, and yet allow it to be removed relatively easily for replacement when needed. 
   SUMMARY OF THE INVENTION 
   The present invention relates to a pick mounting arrangement for a pick arm assembly that has one or more picks or spear-like prongs supported on a movable pick arm, with the pick arm mounted adjacent to a stationary arm, with both the pick arm and the stationary arm supported as a pick arm set on a rotating wheel. The wheel passes through a supply of appropriately sized pieces of material that can be impaled on a pick, such as seed potatoes, the picks protruding through the fixed arm to pierce a single piece of material and carry it with the wheel as the wheel rotates. The pick arm is then actuated to retract from the movable arm in a suitable position during the rotation of the wheel, causing the piece of material, as shown a seed potato, to be stripped from the pick and dropped through a chute to a furrow below the potato planter, in a known way. 
   The head portion of the picks and the openings or bores for the picks in the pick arm are formed to securely hold the picks in position without permitting them to prematurely loosen or move in their mounting bores. The picks each have a tapered exterior surface that extends along a tapered mounting head of the pick that is supported in the pick arm throughout substantially the entire length of the bore in the pick arm. The bore in the pick arm is formed with a mating taper, or cone shape, and the picks are made so the top of the pick head will protrude above the surface of the arm opposite from the side where the picks project. When the tapered head end is seated in the bore, a clamp or lock, as shown, is then placed over the top end of the head of the picks and tightened down against the top end of the head of the pick to provide a longitudinal axial force on the end of the pick and force the exterior tapered surface of the mounting head of the pick and the mating tapered interior surface of the bore in the pick arm to seat tightly, and thus be held securely. 
   The length of the taper on the mounting head and bore, which preferably is a majority of the way through the support bar and the relatively shallow cone angle, ensures that the pick will lock into position with the sharpened end that spears or pierces the seed potatoes projecting out. The pick is held securely from side loads and other loads that have caused loosening in the past. The support bars shown are generally {fraction (5/16)} to ⅜ inches thick. 
   If the picks are to be replaced, the clamp bar or lock bar can be removed and the picks driven out in an opposite direction from the tightening direction to unseat the tapered surfaces. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a fragmentary sectional view at the end of a picker arm showing a prior art mounting for picks in such arm; 
       FIG. 2  is a schematic side view of a typical potato planter wheel showing a sequence of positions of a pick arm set comprises a movable pick arm and a stationary arm for planting potatoes; 
       FIG. 3  is a fragmentary schematic perspective view of a potato planter wheel having pick arm sets made according to present invention installed thereon; 
       FIG. 4  is a schematic view of a pick arm set viewed from an opposite side of the rotating wheel shown in  FIG. 3 ; 
       FIG. 5  is an end view of a pick arm and stationary arm of a pick arm set in a position with the picks protruding through the stationary arm; 
       FIG. 6  is a sectional view taken along line  6 — 6  in  FIG. 5 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring first to  FIGS. 2 ,  3  and  4 , a potato planter  10  is shown only schematically, and by way of example only for orientation. The potato planter  10  has a housing  12 , with a potato supply chamber  14 . The housing  12  has a potato outlet chute  16  that leads to a suitable transfer tube and then down to the ground where the potato will be dropped into a furrow being formed by disks in a conventional manner. The housing  12  mounts a potato pick wheel  18 , which is driven from a suitable drive through a shaft  20 , and is rotated in the direction as indicated by the arrows  22 . The seed potatoes shown at  24  in the potato supply chamber  14  are such that the wheel and thus the pick arms will rotate through this potato supply. A diverter wall  26  is used for keeping the supply of potatoes  24  in a desired location. 
   The pick wheel  18  has a plurality of seed potato pick arm sets or assemblies  30  that are shown only schematically in  FIG. 2 . The potato pick arm sets or assemblies  30  have two arms, including a non-movable or stripper arm  30 A and a movable pick arm  30 B in each of a plurality of positions on the wheel indicated at  29 A– 29 H. The term “stationary” means the arm is fixed in position relative to the planter pick wheel, but the arms do move with the wheel relative to the housing  12 . The planter  10  is provided with a cam control to cause the pick arm  30 B of each set to be moved away from the stripper arm and return toward the stripper arm under a spring load. 
   For example, when the movable pick arm and the stripper arm are together, picks  32 , which are slender, sharpened spears that are carried by the movable pick arm  30 B, will protrude through the associated fixed arm, or stripper arm  30 A, as shown in  FIGS. 4 ,  5 , and  6 . In position  29 A, the protruding ends of the pick or picks (four picks are provided) will engage seed potatoes  24  as the wheel rotates and the pick arm sets or assemblies  30  enter the supply chamber  14  and engage seed potatoes  24  in the supply. 
   As shown schematically at position  29 B, the arm sets move through the supply and pick up an individual seed potato (a section of a larger potato) such as that at wheel position  29 C. The potatoes remain impaled on the picks and are carried around to wheel position  29 F, and then a cam will start to move the movable pick arm  30 B away from the stationary arm or stripper arm. A partially separated pick arm is indicated by the lines between station  29 F and  29 G, and when the arm set is at station  29 G directly above the discharge chute  16 , the pick arm will have been retracted or moved to a position so that the picks  32  will have been stripped away from the seed potato and the potato will fall as shown by potatoes  24 A and  24 B. 
   When at station  29 H, the cam has started to release the movable pick arm and a spring load is provided to return the movable arm to position adjacent the stationary or stripper arm. 
   The picks  32  are prongs or spear-like members that are sharp and will spear a piece of material that can be impaled, such as a seed potato, a piece of a vegetable or other items that can be impaled as the pick arm moves through the supply. The piece of material, as shown a seed potato is carried along as described until a movable picker arm is cammed away from the fixed or stripper arm and the piece of material is stripped off the pick or picks. In  FIG. 3 , separate numbering is used but the positioning of the parts is substantially the same as shown in  FIG. 2  schematically. In  FIG. 3  a potato planter pick wheel  40  has a number of stripper arms  42 A,  42 B,  42 C, and  42 D fixed to the wheel by way of illustration. The arms are bolted to the wheel  40  and the wheel is driven by powering a shaft  44  and rotating the wheel in the direction indicated by arrow  46 . Thus, the arms  42 A– 42 D are stationary relative to the wheel  40 , but move with the wheel relative to the housing  12 . 
   In  FIG. 4 , the fixed arm  42  is shown on the pick wheel  40 . Bolts  49  and  52  are used for fastening the inner end of the fixed arm  42  to the wheel  40 . Bolt  52  has an end for pivotally mounting the base end of the movable pick arm  50 . The movable pick arm  50  has an extension with a cam follower roller  54  rotatably mounted thereon. The movable arm extends out past the periphery of the wheel. A pick support plate  56  is formed at the outer end of the movable pick arm  50 . The pick support plate  56  supports a plurality of individual picks or spears  58  (there are support bores for four picks), that are mounted according to the present invention. The picks  58  pass through an opening in a stripper platform  60  at the outer end of the fixed or stripper arm  42  and sharpened ends protrude from the arm  42 . 
   Schematically shown in  FIG. 3  is the action of the picks  58  as carried by the movable arms. In position  42 A, the picks are piercing or spearing and holding a seed potato  64 A for transport to the position  42 B, where the cam roller  54  of the associated movable pick arm  50  at the position  42 B will have engaged a surface  68  of a stationary cam shown schematically at  66 . The cam surface  68 A causes the movable pick arm to pivot about the pivot bolt  52 . At station  42 B, it can be seen that the pick support plate  56  of the movable pick arm has been retracted from the stripper plate  60 , and the picks  58  for that pick arm have been withdrawn from the seed potato  64 B. 
   When the pick arm sets have traveled to the position shown at  42 C, the cam  66  will have retracted the movable pick arm  50  fully, so the picks  58  are completely withdrawn from the seed potato and stripper plate  60 , and the seed potato shown at  64 C will be falling freely down to the planting chute and into the furrow below. 
   The cam  66  then releases the cam rollers and a torsion spring  70  (see  FIG. 4 ) is used to return the movable pick toward the stripper plate  60  to a home or start position. The movable pick arm  50  is thus snapped back to its position with the pick support plate  56  against the stripper plate  60 , and with the picks  58  protruding from the stripper plate. The torsion spring  70  is mounted over pivot bolt  52  and has ends that rest on mounting bolt  49  and on the mounting of the cam roller. 
   The present invention is directed to the mounting of the individual picks  58 , in the manner shown in  FIGS. 5 and 6 . In  FIG. 5 , the stripper plate  60  and the pick support plate  56  of the movable arm  50  are illustrated separately. More than one row of picks can be used, but in the showing in  FIGS. 5 and 6 , there are places for four picks in a row in the pick support plate  56 . One pick has been removed to show a mounting bore. 
   As shown, the sharpened ends of the picks  58  protrude below the stripper plate portion  60  of the stripper arm  42 , through a large opening or slot  72 . The picks  58  have tapered or sharpened points  74 , and exposed shank lengths  76  and  76 A that can be threaded or roughened in some manner, if desired, to increase the friction with the seed potato that has been speared by the pick. A circular cylindrical portion  78  extends through the opening  72 . The shank can be reduced in diameter and roughened or threaded as shown by shank  76 A or smooth, as shown at  76 B. 
   The picks  58  each have a conically tapered, elongated mounting head portion  80 . The mounting head portions  80  have a very gentle taper angle on their outer surface  81 . 
   The tapered mounting head  80  is of length so that it will pass substantially all the way through a correspondingly conically tapered bore or opening  82  in the pick support plate  56 , as shown. The elongated tapered mounting head  80  is made so that the head top end diameter dimension indicated at  84  in  FIG. 6  is greater than the dimension of the opening  82  at the top surface of the pick support plate  56 . 
   Also, the axial length of the tapered mounting head  80  is preferably greater than the axial length of the bores  82  that receive the mounting heads. That leaves a protrusion of the flat upper or top surface  86  of each of the picks above the surface  88  that is the top of the pick support plate. The difference in dimension between the top end of the tapered bore  82  at surface  88  and the top end of the pick mounting heads may be in the range of 0.010 inch. 
   The difference in size is enough so that the end surfaces of the mounting heads protrude upwardly above the surface  88 , and a clamp bar  90  is put into place overlying the top surfaces  86 . 
   One side of the clamp bar  90  rests on a raised boss  91  and the bar is clamped tightly with a suitable strength cap screw  92 . A high compression force is provided axially along the picks to force the tapered outer surfaces of the heads of the picks against the conical surfaces of the bores  82 . The result is a frictional seating and preferably having support along substantially the entire thickness or axial height of the pick support plate  56  to resist fretting or movement. 
   This long, gentle taper of the mounting head is distinguished from the showing in  FIG. 1 , where a head is countersunk at a substantial angle, for example 60 degrees, and then an attempt is made to seat the pick head. The prior art pick  100  in  FIG. 1  is shown with the countersunk head  102 . It can be seen that the countersunk angle permits only a short taper for the countersunk head against which force can be axially applied, using a clamp bar such as  90 A or a set screw bearing on each pick. The round or cylindrical hole for the major portion of the shank of the prior art pick in  FIG. 1 , that passes through the pick support arm  104 , has to be slightly larger than the pick so it can be slid into place. The clearance will permit play or relative movement as the seed potatoes are engaged and dropped. This will cause premature wear, premature looseness and problems in operation thank with the present invention. 
   The movable arm or pick support arm  50  can be cast material and machined to provide for the pivot housing and the tapered bores  82 , and the picks themselves can be made of any suitable material including hardened tips, if desired. 
   While potatoes have been shown as the example for use of this type of a picker, other materials can be handled in the same manner where they are used for individual picking up and dispensing. Vegetables, such as carrots, and many root crops can be handled with this type of a pick and can be used on rotating wheels for picking pieces from a storage and moving and dropping such pieces at a desired location. 
   The taper angle of the conical surface of the mounting head is about a minimum of two degrees, but preferably less than ten degrees. A preferred taper is three degrees measured from the central longitudinal axis as shown in  FIG. 6  at  106 . The included angle thus can be below twenty degrees with the most preferred included angle at six degrees. 
   The pick length is a factor in the length of the conical seating surfaces that are needed. The length of the conical portion of the head of the pick is at least one half of the diameter  84  of the base end of the conical head. The base is where the conical taper starts. The cone length then will securely support a pick. The pick protrudes from the support plate  56  an amount shown by the double arrow  89  in  FIG. 6 , and at the conical and axial length angle as described, the pick will be secure from side loads on the protruding portion. 
   This means that the tapered head does not need to extend out of the support plate  56  as shown in the preferred embodiment. It will still be secure if the conical length is properly proportioned and kept at the cone angles described. The tapered bore of the cone head of the pick does not extend through the support plate  56 . The bore ends in a cylindrical bore portion at the lower or inner end. The pick can have a short length of cylindrical shank such as that shown at  78  in the cylindrical portion of the support plate bore. 
   Again, the extension of the pick from the support plate affects a moment that needs to be resisted by the support of the conical head. Thus, a conical support substantially the entire thickness of the support plate is desired, and preferably the conical head will protrude through the support plate. This insures securing the pick in place, and also makes installation easy. 
   Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.