Abstract:
An economical wheeled towable folding wheel rake of robust, largely welded construction utilizing a single hydraulic cylinder to fold two opposed wheel rake assemblies via a four bar linkage. The folding mechanism folds the opposed rake assemblies to a compact, symmetrical, easily locked, vertical orientation for shipping transit and storage. The folding mechanism is simple and utilizes few wearing pivots yet enables flotation of the opposed rake assemblies independent of one another and of the main frame of the wheel rake. The opposed wheel rake assemblies are independently adjustable in raking angle, raking width and raking down pressure.

Description:
FIELD OF THE INVENTION 
     The present invention relates to agricultural implements and, in particular, it relates to towable folding wheel rakes useful to form windrows from cut forage. 
     BACKGROUND OF THE INVENTION 
     A primary goal in the harvesting of hay is to dry the hay as soon as possible and remove it from direct exposure to sunlight. The hay must be dried before storage to avoid the problems of mold and spontaneous combustion. Exposing the cut hay to sunlight longer than is required to adequately dry it, however, can result in unacceptable loss of nutritive value of the hay due to deterioration of the protein level. 
     Typically, hay is harvested into approximately five-foot swaths along the ground, and is exposed to sunlight for the initial stage of the drying process. The swaths of hay are then raked into narrow windrows to remove most of the hay from direct contact with the moist ground. The windrow enhances air circulation within the hay, thereby hastening the drying process. 
     Many types of wheel rakes have existed for decades. These comprise angled, tined wheels that are propelled across the ground of a field of cut forage. Contact with the ground while traveling across the ground rotates the wheels and thereby rakes the hay in a desired direction. Of particular interest are V-rakes in which at least two banks of rake wheels are deployed in the shape of a V during operation. Generally, V-rakes employ an arm on each side of a frame to support the wheel rakes. Such V-rakes are used to rake forage into a swath or windrow by raking the forage from the outer edges of the implement inward. V-rakes are preferably adjustable so that the width of the windrow produced is variable and the swath raked on each pass is optimal for the circumstances encountered. For optimal operation, it is preferable to be able to independently adjust the angle of the wheel banks, and the width of their separation. 
     Wheel rakes are subject to repeated structural stresses due to uneven ground and irregular distribution of forage material when propelled through fields of cut hay to form the hay into windrows. The arm assemblies supporting the wheel rakes must have considerable strength in order to bear such stresses successfully. Welded assemblies are thus preferred for their robustness and durability. 
     Another consideration in wheel rake design is the ability of the rake to compensate for variations in the terrain that it passes over. The raking wheels must have some freedom to move up and down while maintaining a certain amount of downward pressure. This freedom of motion is referred to as flotation and the raking wheel assemblies are said to float to compensate for terrain unevenness. It is preferred that each bank of raking wheels be able to float independently of the other bank and that the raking wheels each have some freedom to float within the bank. Such independent flotation promotes efficient raking, and reduces the risk of operational damage to the equipment. It is further beneficial if the down pressure of the wheel rakes can be adjusted to adapt to varying conditions. 
     Aside from raking forage efficiently, wheel rakes must be readily transportable from storage to field and between fields. This generally involves passing through fence gates and transportation on public roadways. Since the wheel rake implement is configured to rake a wide swath in use, there must be provided a means to configure the rake more compactly for transport. A wide variety of schemes for accomplishing this have been disclosed in the prior art. Some involve folding the V-rake by raising the wheel supporting arms from a horizontal position used when raking a field to a vertical position for transit. This can be accomplished manually or with powered assist, commonly with hydraulics. Hydraulic folding provides for operator convenience as well as improved safety since the operator need not risk contact with the relatively heavy machinery while it is being folded. V-rakes that fold upward to allow for transport include those disclosed in U.S. Pat. Nos. 4,977,734, and 4,974,407 to Rowe et al., 4,753,063 to Buck, 4,214,428 to Caraway and 4,183,198 to Sligter. 
     Wheel rake implements must share the public right of way with automotive and pedestrian traffic. Safety concerns dictate that rake arms folded in a vertical position be securely held in their vertical orientation. Accordingly, many folding wheel rake designs include various safety lock devices, such as chains and locking collars to prevent the movement of the rake arms from a vertical position. Safety lock devices can require relatively complex intervention on the part of the operator to engage. Operation and engagement of safety locks should be as simple as possible, to encourage their routine use. 
     One of the significant costs involved in the production and delivery of hay rakes is that of shipping. Wheel rakes, however, are necessarily bulky in order to accomplish their intended task, and can present extraordinary challenges with regard to shipping. One approach to the challenge of shipping wheel rakes has been to design rakes to be assembled from many small sub-components. Such rakes are shipped disassembled, and can present a quite compact shipping package. This approach, however, creates a rake that is largely bolted together, and more prone to operational damage than a rake that is substantially welded in construction. Additionally, the implement dealer or end user must expend considerable labor to assemble the rake. Welded rakes, on the other hand, offer superior strength and durability but also comprise large individual rake components that do not lend themselves well to compact shipping packages. A V-wheel rake of substantially welded construction, that could be compactly configured for shipping and required minimal assembly upon arrival at its intended location, would provide distinct advantages. 
     Another factor affecting both the manufacturing and operating cost of hydraulically folded wheel rakes is the number of hydraulic components. Many folding rakes employ multiple hydraulic piston and cylinder assemblies to fold the rake arms. Efforts to reduce costs have lead to the development of linkages that allow a single piston and cylinder assembly to fold both arms. In order to raise the rake arms symmetrically, a variable geometry quadrilateral can be employed. A hydraulic piston and cylinder assembly forms the diagonal of a quadrilateral. When the piston and cylinder assembly is extended, the other diagonal of the quadrilateral is shortened to lift the rake arms. When the piston and cylinder assembly is retracted, the other diagonal is extended to lower the arms. In general, these linkages can be somewhat complex, heavy and often have multiple pivots which require frequent lubrication and tend to wear. U.S. Pat. Nos. 5,313,772 and 5,263,306 to Tonutti, assigned to Tonutti S. P. A., disclose examples of wheel rakes employing a single piston and cylinder assembly in conjunction with a quadrilateral linkage. 
     A single piston and cylinder assembly could be used to extend between and interconnect the lift arms directly. Particularly if flotation is allowed at the interconnection points, however, a single piston and cylinder raising approach would tend to lift the arms unequally, with one arm being vertical and the other hanging to one side. This creates the appearance, if not necessarily a greater likelihood, that a rake arm may fall while the rake is in transit. It may create anxiety or concern that the rake arms are not entirely raised in the mind of the operator or motorists passing near the rake while it is in transit. It is preferable that rake arms be raised to a symmetrical vertical position. 
     It would be desirable to produce an economical, towable, folding V-rake, the folding mechanism of which is actuated by a single hydraulic piston and cylinder assembly, which folds the arms to a compact, symmetrical, easily locked, vertical orientation for shipping, transit and storage, without employing a complex linkage. It would be preferable for such a rake to allow for convenient independent adjustment of the angle and width of the raking assemblies and of the down pressure of the raking wheels. The rake would ideally be constructed largely of welded components, to provide a robust wheel rake requiring minimal assembly by the seller or end user. 
     SUMMARY OF THE INVENTION 
     The present invention in large measure solves the above noted problems, providing a folding rake with an improved folding mechanism. The rake hereof employs a single hydraulic piston and cylinder assembly to fold both arms of a V-rake by a simple, light weight mechanism providing for independent flotation, having relatively few wearing pivot points, and yet still raising the rake arm assemblies to secure vertical positions. Additionally, the V-rake hereof provides for independent adjustment of transport wheel width, rake angle, raking width and wheel down pressure. The towable V-wheel rake of the present invention is uniquely foldable for compact shipping and storage, without the necessity of significant disassembly. 
     The folding mechanism comprises a single hydraulic piston and cylinder assembly secured at one end to the rake frame or carriage. The hydraulic piston rod engages a tower on a first wheel rake assembly or subframe and rotates the first wheel rake assembly about a pivot point. A linkage assembly includes a bellcrank rotatable about the same first wheel rake assembly pivot point, with the bellcrank linked to a pushrod which is further linked to a second tower on the second wheel rake assembly or subframe. The bellcrank end of the pushrod and the tower end of the pushrod are configured to travel in unequal arcs while the wheel rake assemblies rotate in equal arcs, thereby enabling the arms of the wheel rake assemblies to be raised to a symmetrical vertical transport position, while still providing for flotation of the lift arms, independent of one another, when in the unfolded working position. 
     When the wheel rake assemblies are in the down, working position for raking, they are supported by adjustable tension compression springs, thus providing for variable down pressure and an independent adjustment of down pressure for each wheel rake assembly. 
     Each wheel rake assembly further includes a beam carrying a plurality of raking wheels. The beam is pivotably adjustable to vary the angle of the wheel bank carried by the beam relative to the direction of travel of the V-rake. This is accomplished by pivotably fixing one end of a rod to the rake arm and providing a series of connection points spaced upon the beam. The second end of the rod is selectively engageable by any of the connection points. 
     Additionally, the raking width may be varied independently for each side of the rake. Each rake arm comprises a slider that telescopes in and out relative to a fixed sleeve, and is selectively fixable at a plurality of different positions of width. 
     The rake frame is carried by ground engaging transport wheels. The wheels are independently adjustable long the width of the frame by clamping them at various locations upon the transverse bar of the wheel rake. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front perspective view of a wheel rake in accordance with the present invention, with the arms of the rake in the horizontal raking position; 
     FIG. 2 depicts detail of area A from FIG. 1; 
     FIG. 3 depicts detail of area B from FIG. 1; 
     FIG. 4 is a front perspective view of the wheel rake with the arms in the vertical transport position; 
     FIG. 5 depicts detail of area C from FIG. 4; 
     FIG. 6 depicts detail of area D from FIG. 4; 
     FIG. 7 depicts detail of area E from FIG. 1; 
     FIG. 8 depicts detail of area F from FIG. 1; 
     FIG. 9 a  is a schematic representation of the relationship of the lengths of the members of a four bar linkage that comprises the folding mechanism of the folding wheel rake in the folded and unfolded configurations showing the need for two different lengths of a pushrod to fold the rake; and 
     FIG. 9 b  is similar to  9   a  but shows how the folding mechanism of the folding wheel rake resolves this problem. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring in particular to FIGS. 1 and 4, a folding wheel rake  10 , in accordance with the present invention, generally includes a primary frame  12 , a right wheel rake assembly  14 , a left wheel rake assembly  16 , a lift assembly  18 , and ground engaging wheels  19 . 
     The primary frame  12  generally includes a draw bar  20 , at the front end thereof, and a transverse bar  22 . The draw bar  20  includes, at its front end, a hitch  24  adapted for connection to a prime mover, preferably a tractor (not shown). The draw bar  20  is removably received within a channel formed by gussets  28 , and is retained therein by bolts or other suitable fastening device. Retainer pins  30 ,  32  can be stowed in apertures placed in gussets  28 . 
     Transverse bar  22  is supported by ground-engaging transport wheels  19 . Wheel strut assemblies  36  are shiftably clamped to transverse bar  22  for support of wheels  19  along the transverse bar  22 . 
     The right end of transverse bar  22  supports right wheel rake assembly retainer  38 . Right wheel rake assembly retainer  38  includes right wheel rake assembly support spring mount  40 . A right wheel rake assembly pivot mount  42  is carried by transverse bar  22  inboard of right wheel rake assembly retainer  38 . A hydraulic piston and cylinder assembly pivot mount  44  is located in the center region of transverse bar  22 . Referring to FIGS. 3,  4  and  6 , right pivot stop  52  and left pivot stop  54  are carried by transverse bar  22 . Left wheel rake assembly pivot mount  46 , left wheel rake assembly retainer  48 , and left wheel rake assembly spring mount  50  are mounted at the left end of transverse bar  22  in a mirror image to similar parts at the right side, and subcomponents thereof that are similar as between the right and left sides of the folding wheel rake  10  are for convenience annotated with like numerals in the drawings. 
     Left wheel rake assembly spring mount  50  (depicted in FIG. 5) and right wheel rake assembly spring mount  40  (see FIG. 1) are carried by the base  56  of right and left wheel rake assembly retainers  38 ,  48 , respectively. The spring mounts  50 ,  40  each include (see FIG.  1  and FIG. 5) a helical compression spring  58 , and a spring cap  60 , secured on top of the compression spring  58 . Spring cap  60  further presents a threaded bore  62  centrally located therein. Adjustment screw  63  is threaded into threaded bore  62 . Spring cap  60  is secured to the top of spring  58  by a plurality of bent tabs  64 , bolts (not shown), or other suitable fastener and includes a recess  65  sufficiently large to receive the head  66  of adjustment screw  63 . The bottom of springs  58  are permanently welded to the base  56  of respective right and left wheel rake assembly retainers  38 ,  48 . 
     Referring to FIGS. 1,  3  and  6 , right wheel rake assembly  14  generally includes right arm assembly  70 , right beam assembly  72 , and right adjustment rod mechanism  74 . Right arm assembly  70  is pivotably secured to transverse bar  22  by pivot pin  76  at right wheel rake assembly pivot mount  42 . 
     Right arm assembly  70  includes sleeve  77  and slider  78 . Slider  78  fits slidably within sleeve  77  in a telescoping fashion. 
     FIG. 7 depicts particular details of right wheel rake assembly  14 . As previously noted, right slider  78  fits slidably within right sleeve  77  in a telescoping fashion. Slider  78  presents slider lock pin holes (not shown) which are alignable with sleeve lock pin holes  81  to receive a lock pin (not shown) therethrough. 
     The distal end of slider  78  further includes beam angle pivot assembly  82 , pivotably supporting right beam assembly  72  about a vertical axis on pivot pin  84 . Beam angle pivot assembly  82  includes beam angle pivot clevis  86 . Beam angle pivot clevis  86  supports beam wobble pivot assembly  88 , including shaft  90  and shaft receiving sleeve  91 , and beam assembly stop  92 . 
     Beam assembly  72  includes beam  96 , rake wheel supports  98 , and rake wheels  100 . Stops  101  are carried on beam  96 , and straddle stop  92 . Shaft  90  of beam wobble pivot assembly  88  is fixedly carried by beam  96 , and is rotatably received within sleeve  91  for pivotal support of the beam assembly  72  by the arm assembly  70 . 
     Referring to FIG. 8, the adjustment rod mechanism  74  comprises adjustable threaded rod  105  extending between multi-point adjustment clevis  102  secured to beam  96 , and adjustment rod attachment  103  carried on the front face of sleeve  77  (see FIG.  3 ). Clevis  102  presents a plurality of angle adjustment apertures  104  each adapted for receiving distal eye  106  of adjustment rod  105 . Distal eye  106  can be secured by angle adjustment lock pin  108 . Referring to FIGS. 3 and 6, proximal eye  110  of adjustment rod  76  is pivotably, removably secured to adjustment rod attachment  82  by pin  112 . 
     Left wheel rake assembly  16  is generally similar to right wheel rake assembly  14 , principally being a mirror image of the right side, and subcomponents thereof that are similar as between the right and left sides of the folding wheel rake  10  are for convenience annotated with like numerals in the drawings. 
     The lift assembly  18  generally includes a hydraulic piston and cylinder assembly  114 , a bellcrank assembly  116 , a pushrod  118  and a crank assembly  120 . 
     The hydraulic piston and cylinder assembly  114  includes a piston rod  122  presenting attachment end  124  and a cylinder  126  having attachment end  128  received by pivot mount  44 . 
     Bellcrank assembly  116  includes piston rod receiving tower  130  and crank arm  132 . Piston rod receiving tower  130  is fixedly secured on top of sleeve  77  of right wheel rake assembly  14 . Piston tower  130  presents flotation slot  134 , the long axis of which is generally parallel to the long axis of sleeve  77 . Crank arm  132  is fixedly secured to sleeve  77  of right wheel rake assembly  14  and rotates about pivot pin  76  received by right wheel rake assembly pivot mount  42 . Crank arm  132  includes locking aperture  136  alignable with a right lock aperture (not shown) in pivot mount  42  when right wheel rake assembly  14  is in the vertical position. Lock pin  138  is receivable through locking aperture  136  and the locking aperture in pivot mount  42 . Crank arm  132  is pivotally coupled to pushrod  118  by pin  140 . Pushrod  118  includes angled stub  142  and a tower link collar  144  at opposite ends. 
     Crank assembly  120  includes pushrod tower  150  and angled lock brace  152 . Pushrod tower  150  is fixedly secured on top of sleeve  77  of left wheel rake assembly  16 . Push rod tower  150  presents push rod tower flotation slots  154 , the long axes of which are generally parallel to the long axis of sleeve  77 . Brace  152  is pivotably mounted at left wheel rake assembly pivot mount  46  and is fixedly attached to sleeve  77  of left wheel rake assembly  16 . Brace  152  includes locking aperture  156  adapted to receive lock pin  158  therethrough. Locking aperture  156  aligns with a locking aperture (not shown) on left wheel rake assembly pivot mount  46  when the folding wheel rake  10  is in the folded position. 
     The hydraulic piston and cylinder assembly  114  is secured at cylinder attachment end  128  to the hydraulic piston and cylinder assembly pivot mount  44  on transverse bar  22 , rotating about pin  146 . Rod attachment end  124  is secured slidably and rotatably within piston tower flotation slots  134  by slot engagement pin  148 . Angled stub  142  is rotatably secured to crank arm  132  by pin  140 . Tower link collar  144  slidably and rotatably secures pushrod  118  to pushrod tower  150  at pushrod flotation slot  154  by link pin  155 . 
     In operation, the wheel rake  10  is towed through the fields to rake forage by a tractor or other prime mover. The general operation of wheel rakes is well known in agriculture and will be apparent to one skilled in the art. Transport of the rake from one field to another is generally accomplished by raising the wheel rake assemblies  14  and  16  to the transport position by application of hydraulic pressure from the tractor&#39;s hydraulic system. This provides clearance to pass through gates and down narrow paths as well as preventing damage to rake wheels  100  when in transit. 
     While normally pulled by a tractor, the folding wheel rake  10  may also be connected to another type of vehicle, such as a pickup truck, for transport. 
     With wheel rake assemblies  14 ,  16  in the raking position, slot engagement pin  148  is centered in flotation slots  134 . This enables freedom of flotation of right wheel rake assembly  14  both upwardly and downwardly from its neutral position. Likewise, link pin  155  is centered in pushrod tower flotation slot  154  when left wheel rake assembly  16  is in the raking position enabling flotation in both directions. 
     When folding of wheel rake assemblies  14 ,  16  is desired, hydraulic pressure is applied to piston and cylinder assembly  114  retracting piston rod  122 . Slot engagement pin  148  is drawn to the medial end of flotation slot  134 . Force is then applied to right wheel rake assembly  14  rotating it upwardly and inwardly. As wheel rake assembly  14  rotates, attached crank arm  132  rotates downwardly and outwardly pulling pushrod  118  at angled stub  142 . Force is transmitted to tower link collar  144  and link pin  155 , drawing link pin  155  medially until it contacts the medial end of pushrod tower flotation slot  154 . Left wheel rake assembly  16  is then rotated upwardly and inwardly until it reaches the upright transport position. Right and left pivot stops  52 ,  54  prevent wheel rake assemblies  14  and  16  from traveling beyond the transport position. Lock aperture  136  is then aligned with right lock aperture  137 , and lock pin  138  may be inserted to secure the right wheel rake assembly  14  in the transport position. Likewise, locking aperture  156  is aligned with left lock aperture  160  and secured by a lock pin  158 . 
     A reverse process enables unfolding of the folding wheel rake  10 . Lock pins  138  and  158  are removed from apertures  136  and  156 . Piston rod  122  is extended from hydraulic piston and cylinder assembly  114  pushing slot engagement pin  148  against flotation slot  134  causing wheel rake assembly  14  to rotate outwardly and downwardly. Integral crank arm  132  rotates so that pin  140  is rotated upwardly and inwardly carrying with it angled stub  142 . Pushrod  118  forces link pin  155  laterally causing pushrod tower  150  to rotate outwardly and downwardly carrying with it left wheel rake assembly  16 . Slot engagement pin  148  and link pin  155  are ultimately approximately centered in their respective flotation slot  134  and pushrod tower flotation slot  154 . 
     It is desirable that wheel rake assemblies  14 ,  16  achieve a symmetrical vertical orientation when folded. Referring to FIGS. 9 a  and  9   b , the presence of flotation slot  134  and pushrod tower flotation slot  154  create free play that is desirable for flotation. However, the free play complicates achieving symmetrical folding. The radius of the arc traveled by pushrod post  140  has been adjusted to vary from the arc of tower link pin  155 . Additionally, the portion of the arc transcribed by pushrod post  140  may vary from that of tower link pin  155 . This arrangement allows pushrod post  140  to travel an arc of approximately 90 degrees while link pin  155  travels an arc of approximately 93 degrees achieving secure, symmetrical, compact, vertical folding as depicted in FIG.  4 . 
     Another way of describing this arrangement is to consider the lift assembly  18  as a four bar linkage in which one of the linkage bars is of variable length. The variable length bar achieves its shortest length when under tension. The other three bars are of fixed length. The ground bar represents the distance between right wheel rake assembly pivot mount  42  and left wheel rake assembly pivot mount  46 . The second bar represents the radius of the arc traveled by pushrod post  140 . The third bar is defined by the radius of the arc traveled by link pin  155  about left wheel rake assembly pivot  46 . The effective length of pushrod  118  forms the fourth bar. Effective length is the straight-line distance between pushrod post  140  and link pin  155 . The effect of tower link pin  155  sliding in pushrod tower flotation slot  155  and of flotation slot  154  turning approximately 90 degrees during the folding process is to vary the effective length of pushrod  118 . 
     If it is desired to rake with only one wheel rake assembly lowered, left wheel rake assembly  16  may be left in the transport position locked by pin  158 . Link pin  155  may be removed from pushrod tower flotation slot  154  and right wheel rake assembly  14  may be lowered independently. To return to raking with both wheel rake assemblies simultaneously lowered pushrod  118  may be reconnected to pushrod tower rotation slot  154  by link pin  155 . 
     With the folding wheel rake  10  in the unfolded, raking configuration as in FIGS. 1 and 7 the folding wheel rake  10  may be drawn by a prime mover, such as a tractor, by attachment of the hitch  24 . The general use of wheel rakes for raking forage is well known in the art. 
     Referring to FIG. 7, the width of separation of the wheel rake assemblies  14 ,  16  may be adjusted by telescoping sliders  78  into or out of sleeves  77 . Sliders  78  may be secured in any of a plurality of positions by inserting a pin (not shown) through a sleeve lock pin hole  81  and one of a plurality of slider lock pin holes (not shown). Other locking mechanisms may be used without departing from the spirit and scope of the invention. 
     Referring to FIG. 8, the angle of beam assemblies  72  may be adjusted relative to the direction of travel of the folding wheel rake  10  independently of width adjustment. Angle adjustment of the right wheel rake assembly  14  is achieved by aligning distal eye  106  of adjustment rod  75  with any of a plurality of angle adjustment positions  104  and inserting a pin  108  therethrough to achieve the desired angle. 
     Raking down pressure may also be adjusted independently of other variables. Referring to FIGS. 4 and 5, rake wheel rake assemblies  14  and  16  are raised to provide access to adjustment screws  63 . The adjustment screw  63  may then be turned into or out of spring cap  60  in order to increase or decrease the length to which it extends from spring  58 . When rake wheel rake assemblies  14  and  16  are lowered to raking position, it will be understood that the spring  58  will be compressed to a greater degree as the screw  63  extends further from the spring  58 . 
     To facilitate shipping and storage the folding wheel rake  10  may be folded to a very compact configuration. Sliders  78  are telescoped fully into sleeves  77 . Wheel rake assemblies  14  and  16  are folded to the transport position. Angle adjustment rods  74  are released. Beam assemblies  72  are then rotated until generally parallel with arm assemblies  70 . Angle adjustment rods  74  are likewise made generally parallel to arm assemblies  70   
     Referring to FIG. 9 a , radius A represents the length of crank arm  132 . Radius B is the length of crank assembly  120 . Length C is the length of pushrod  118  needed with the wheel rake  10  in the unfolded position. Length D is the length of pushrod needed with the wheel rake  10  in the folded position. Angle E and angle F represent the arcs traveled by the right wheel rake assembly  14  and the right wheel rake assembly  16  respectively when moving from the unfolded position to the folded position. 
     If radius A is equal to radius B and tower link pin  155  starts at the center of tower flotation slot  154  then the transition form the unfolded position to the folded position will leave the left wheel rake assembly slightly short of a fully vertical position. This would required that length D be less than length C. It is unnecessarily complex for pushrod  118  to vary in length during the folding process. 
     Therefore (refer to FIG. 9 a ), it is beneficial for radius A to be larger than radius B so that the left wheel rake assembly  16  is pulled to a fully vertical position upon folding. When radius A′ and radius B′ are chosen appropriately it will be seen that length C′ may be equal to length D′ and that left wheel rake assembly  16  travel in arc F′ while tower link pin  155  travels in arc G. This arrangement enables secure, compact, symmetrical folding of both right wheel rake assembly  14  and left wheel rake assembly  16  wheel still employing a simple linkage with few wear points. 
     The present invention may be embodied in other specific forms without departing from the essential attributes thereof; therefore, the illustrated embodiments should be considered in all respects as illustrative and not restrictive, reference being made to the appended claims rather than to the foregoing description to indicate the scope of the invention.