Abstract:
A manually operable push-type topdresser includes a reciprocating screen apparatus at the bottom of a material hopper that is operable to reduce the particulate material within the hopper to a uniform size before discharging the particulate material onto the surface of the ground. The topdresser includes a ground drive mechanism to power the reciprocation of an upper screen member when the topdresser is moved. The drive mechanism includes a front drive wheel mounted on one end of an axle and a freely rotatable wheel mounted on the opposing end of the axle to facilitate maneuverability of the topdresser in tight spaces. The reciprocation of the upper screen prevents bridging of the particulate material within the hopper. A control linkage shifts the ground drive mechanism between operable and inoperable modes by moving a shift collar to control engagement of the reciprocation drive with a cam member rotatable with the drive wheel.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims domestic priority on U.S. Provisional Patent Application Ser. No. 61/611,120, filed on Mar. 15, 2012, the content of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to an apparatus for distributing granular material, such as sand, top soil, fertilizers, compost and other soil additives over the surface of the ground, including top dressing to the surface of turf-covered ground, and, more particularly, to a topdresser that utilizes a pair of screens arranged in a reciprocating manner to distribute the material within the hopper to the surface of the ground. 
     BACKGROUND OF THE INVENTION 
     Compost is generally defined as any organic material that has undergone a biodegradation process. Typical examples of compost are decomposed leaves, sewage sludge which has been mixed with wood chips or other material to allow air to permeate the sludge, and mushroom soil. Compost is usually applied to golf courses, lawns and park grounds as a thin even top dressing. In the past, the proper application of compost has required the use of small material spreading machines. Whether of the pull type or self propelled, material spreading machines are commonly used for applying dressings to turf-covered ground, such as ground surfaces used for various athletic activities, and especially football fields and golf courses. Such material spreading machines commonly include a hopper and a moving belt which passes within or beneath the hopper to convey the material to a distribution mechanism, such as a rotating brush, that dispenses the material onto the surface of the ground. 
     Typically, compost material spreading machines are equipped with a rotating brush distributing apparatus, which is usually mounted at the rear of a moving belt that carries the compost to the rotating brush distributor. One of the large material spreading machines is found in U.S. Pat. No. 4,804,145, granted to Shaun A. Seymour on Feb. 14, 1989, in which the hopper is a substantially rectangular spreader box with a rotating brush at the discharge end of the spreader box to distribute the compost onto the top surface of the ground. A similar apparatus is disclosed in U.S. Pat. No. 6,202,944, granted to Kevin McCrory on Mar. 20, 2001, wherein the hopper meters the flow of compost into a thin layer to be presented to the rotating brush distributor that dispenses the compost onto the top surface of the ground. 
     In some material spreading machines, such as is depicted in U.S. Pat. No. 4,634,056, issued on Jan. 6, 1987, to Carroll Precure, the compost is distributed directly by the endless belt extracting the compost from within the hopper. In U.S. Pat. No. 4,155,315, issued to John Dobbins on May 22, 1979, the compost is distributed directly from the hopper onto the top surface of the ground, the rate of application of the material from the hopper being controlled by a slidable plate positionable across the opening in the hopper through which the material flows. A ground-engaging roller supported on the frame of the Dobbins material spreading machine provides sufficient vibration to the compost within the hopper to prevent the material from bridging over the discharge opening. A rotary screening device is disclosed in U.S. Pat. No. 6,892,516, granted on May 17, 2005, to Salvatore Ardagna, by which material, including compost, can be sifted and separated for appropriate application subsequently to the separation action of the apparatus. 
     All of these known compost material spreading machines are particularly adapted for utilization on athletic fields and golf courses, as the machines carry large quantities of compost for topdressing large areas of turf-covered ground. None of these known material spreading machines are particularly well adapted for use in small locations, such as a residential yard, in which maneuverability is needed and manual control over the distribution of the compost material over the ground. One of the problems with spreading compost is that compost is not uniformly sized. The variably sized compost particles will not go through a small lawn push spinner spreader or through a small lawn push drop spreader. A V-shaped hopper with a roller at the bottom of the hopper will accommodate the varying particle size, but is only effective if the compost material is dry. Compost material that has moisture will have a tendency to clump and bridge over the opening at the bottom of the V-shaped hopper. Thus, commonly used fertilizer spinner and drop spreaders typically used on small residential lawns, are not effectively operable to provide a topdressing of compost over turf-covered ground. 
     Accordingly, it would be desirable to provide a manually operable push-type configuration of compost spreading machine that can be used in small locations for the application of limited quantities of compost or other granular soil additive materials to the top surface of turf-covered ground. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to provide a manually operable push-type topdresser for spreading compost or other particulate material over the surface of the ground in an even, thinly applied layer. 
     It is another object of this invention to provide a reciprocating apparatus within the hopper of the topdresser to reduce the particulate material being discharged to a uniform size that facilitates the formation of a thinly applied, even layer of particulate material on the surface of the ground. 
     It is a feature of this invention that the reciprocating apparatus is formed as a pair of vertically spaced screens positioned at the bottom of the material hopper, at least one of the screens being reciprocal relative to the other screen. 
     It is another feature of this invention that the upper screen is connected to a drive apparatus to cause reciprocation thereof as the topdresser is moved along the surface of the ground. 
     It is still another feature of this invention that the lower screen is stationary relative to the hopper so that the upper screen reciprocates over the lower screen. 
     It is an advantage of this invention that the particulate material, such as compost, is reduced to a uniform size as the material is being discharged from the hopper onto the surface of the ground. 
     It is another advantage of this invention that the upper reciprocating and lower fixed screens create a sifting action that breaks up the variably sized compost particles to allow the compost particles to drop through the two screens onto the surface of the ground below the hopper. 
     It is another advantage of this invention that the configuration of the push-type topdresser is maneuverable to accommodate utilization within tight confines of a residential yard. 
     It is yet another feature of this invention that the flow of the particulate material for discharge from the hopper is manually controlled. 
     It is still another advantage of this invention that the manual control of the flow of material from the hopper of the topdresser facilitates the application of particulate material in small locations, such as a residential yard. 
     It is yet another advantage that the operation of the manually operable, push-type topdresser is less dependent of the moisture content of the compost being applied from the topdresser. 
     It is another feature of this invention that the material hopper is not provided with a roller to meter flow of particulate material to a distribution device for applying the particulate material to the surface of the ground. 
     It is still another feature of this invention that the configuration of the manually operable push-type topdresser is sized to permit manual operation of the topdresser even when the particulate material being distributed includes a high moisture content. 
     It is still another object of this invention to provide a ground drive mechanism that selectively powers the reciprocation of the upper screen when the topdresser is moved over the surface of the ground. 
     It is a further feature of this invention that the drive mechanism includes a front wheel axle connected to a drive wheel and having a freely rotatable wheel mounted thereon. 
     It is a further advantage of this invention that the freely rotatable wheel facilitates the manipulation of the topdresser is small, tight locations. 
     It is still a further feature of this invention that the drive wheel is operably connected to a rocker mechanism that powers the fore-and-aft reciprocation of the upper screen. 
     It is yet a further feature of this invention that the rocker mechanism includes a lobed cam member that is rotatable with the drive wheel and a laterally shiftable device that moves the reciprocating drive into and out of engagement with the cam member. 
     It is still a further advantage of this invention that the reciprocation drive mechanism is selectively engagable to operate the reciprocation of the upper screen. 
     It is yet another advantage of this invention that the reciprocating motion of the drive mechanism and the reciprocating upper screen creates sufficient vibration that prevents compost material from bridging within the hopper. 
     It is yet another object of this invention to provide a manually operable push-type topdresser for spreading compost or other particulate material that is durable in construction, inexpensive of manufacture, carefree of maintenance, facile in assemblage, and simple and effective in use. 
     These and other objects, features and advantages are accomplished according to the instant invention by providing a manually operable push-type topdresser having a hopper for carrying a supply of particulate material and a reciprocating screen apparatus that is operable to reduce the particulate material to a uniform size and to discharge the particulate material onto the surface of the ground. The topdresser includes a ground drive mechanism to power the reciprocation of the upper screen member when the topdresser is moved along the ground. The drive mechanism includes a front drive wheel mounted on one end of an axle and a freely rotatable wheel mounted on the opposing end of the axle to facilitate maneuverability of the topdresser in tight spaces. The reciprocation of the upper screen prevents bridging of the particulate material within the hopper. A control linkage shifts the ground drive mechanism between operable and inoperable modes by moving a shift collar to control engagement of the reciprocation drive with a cam member rotatable with the drive wheel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The advantages of this invention will be apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein: 
         FIG. 1  is a top plan view of the push-type compost spreading apparatus incorporating the principles of the instant invention; 
         FIG. 2  is a bottom plan view of the push-type compost spreading apparatus shown in  FIG. 1 ; 
         FIG. 3  is a side elevational view of the compost spreading apparatus shown in  FIG. 1 ; 
         FIG. 4  is a front elevational view of the compost spreading apparatus shown in  FIG. 1 ; 
         FIG. 5  is a rear elevational view of the compost spreading apparatus shown in  FIG. 1 ; 
         FIG. 6  is an enlarged partial bottom plan view of the hopper and screen distribution mechanism corresponding to the circle A-A in  FIG. 2 ; 
         FIG. 7  is an exploded view of the hopper and dual screen distribution mechanism; and 
         FIG. 8  is an exploded view of the ground drive mechanism for reciprocating one of the screens of the dual screen distribution mechanism shown in  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIGS. 1-7 , a compost spreading apparatus incorporating the principles of the instant invention can best be seen. Left, right, front and rear references are use as a matter of convenience and are determined by standing at the rear of the apparatus  10  where the push handle assembly  15  is located and facing the push handle assembly  15  to push the apparatus  10  along a forward direction of operative travel. The compost spreading apparatus  10  has a frame  11  supporting a forward pair of ground-engaging drive wheels  12  and a rearward caster wheel  14  that provide mobility for the apparatus  10  over the surface of the ground. The push handle assembly  15  extends rearwardly from the frame  11  to provide the ability to move and direct the movement of the apparatus  10 , as will be described in greater detail below. 
     The rearward portion of the frame  11  is formed with a triangular caster wheel mount  13  that extends rearwardly from the hopper  20  and terminates in an apex where the caster wheel  14  is pivotally supported. The push handle assembly  15  is affixed to the triangular caster wheel mount  13  so that the operator can push on the handle  15  to move the apparatus  10  in a forward direction, or pull the handle  15  to move the apparatus  10  rearwardly, as well as push the handle  15  sideways to turn the apparatus  10 , while the caster wheel  14  allows the turning movement. Pivotally mounted on the push handle  15  is a drive actuator lever  16  that is operable to initiate the ground drive mechanism, as will be described in greater detail below. 
     The hopper  20 , best seen in  FIGS. 1 ,  2   6  and  7 , is formed with vertical walls  21  at the front, back and sides to define a cavity that will contain a supply of compost that is not too heavy, even if containing moisture, that would prevent a single person from moving the apparatus  10  when fully loaded with compost. The hopper  20  is formed with a first stationary screen member  23  fixed to the bottoms of the vertical walls  21  and a second movable screen  25  mounted on top of the first stationary screen  23  for fore-and-aft reciprocal movement over top of the stationary screen  23 . A pair of guide members  26  located at the forward and rearward ends of the hopper  20  restrain and guide the movement of the movable screen  25  within the hopper  20  over top of the stationary screen  23 . The movement of the movable screen  25  creates a sifting action that breaks up the variably sized compost particles to allow the compost particles to drop through the two screens  23 ,  25  onto the surface of the ground below the hopper  20 . 
     The forward portion of the frame  11  includes a drive housing  19  encompassing the front drive axle  32  extending between the front wheels  12 . As best seen in  FIG. 8 , the front axle  32  is attached to one of the front wheels  12   a  through a fastener (not shown) that secures the front axle  32  to the front drive wheel  12   a  so as to be rotatable with the driving front wheel  12   a . The opposing front wheel  12   b  is supported in a bearing  33  that allows the wheel  12   b  to freely turn on the front axle  32 . One skilled in the art will recognize that the ground drive mechanism  30  does not need to be secured to both front wheels  12 , as the freely rotatable opposing wheel  12   b  facilitates the turning of the apparatus  10  when the operator pushes sideways on the push handle assembly  15 . 
     The drive mechanism  30  includes a rocker shaft weld assembly  35  formed with a pair of transversely spaced, star-shaped rocker members  36  centered over the axle  32  with a shift collar  37  mounted on a transverse rod  38  interconnecting the rocker members  36 . The rocker member  36   a  closest to the drive front wheel  12   a  has a cam follower  39  mounted thereon. The cam follower  39  is engagable with a cam member  40  fixed on the axle  32  so as to be rotatable therewith. The cam member  40  is preferably formed with a machined groove therein that establishes a path for the cam follower  39  to engage and follow in a conventional manner to oscillate the rocker member  36  on which the cam follower  39  is affixed. As is best seen in  FIG. 8 , each of the rocker members  36  is formed with an elongated central opening through which the front axle  32  passes. The elongated central opening on the rocker members  36  enables the rocker members  36  to shift forwardly and rearwardly as the cam follower  39  rolls along the machined groove in the cam member  40 . 
     The downwardly extending arm of each of the rocker members  36  is coupled to a longitudinally extending drive arm  42  such that the drive arms  42  are moved forwardly and rearwardly in conjunction with the corresponding movement of the rocker members  36  caused by the cam follower  39  moving along the machined groove in the rotating cam member  40 . As is best seen in  FIG. 2 , the downwardly extending arms of the rocker members  36  project through openings in the bottom surface of the drive housing  19  so that the drive arms  42  can extend rearwardly thereof into engagement with a connecting rib  28  on the front of the movable screen  25 . Thus, when the rocker members  36  move forwardly and rearwardly in conjunction with the cam follower  39  moving on the rotating cam member  40 , the drive arms  42  reciprocate the movable screen  25  longitudinally over the stationary screen  23 . 
     Referring again to the exploded view of the drive mechanism  30  in  FIG. 8 , and to FIGS.  1  and  3 - 6 , the activation lever  16  includes a connecting link  17  that couples the activation lever  16  to a shift lever  18  pivotally mounted on the drive housing  19  to shift the drive mechanism  30  between operative and inoperative configurations. The shift lever  18  is connected to an L-shaped transfer quadrant  43  pivotally supported on a pivot bracket  44  and having a shift driver  45  connected at the forward arm thereof. The shift driver  45  is positioned within the confines of the shift collar  37  mounted on the transverse rod  38  extending between the rocker members  36 . When the activation lever  16  is depressed onto the push handle assembly  15 , the connecting link  17  pulls on the shift lever  18 , which in turn pivotally rotates the transfer quadrant  43  to move the shift driver  45  laterally and, thereby, move the shift collar  37  laterally. The movement of the shift collar  37  causes a corresponding lateral movement of the rocker weld assembly  35  to engage the cam follower  39  with the machined groove in the cam member  40  to effect the reciprocating movement of the movable screen  25 . Conversely, moving the activation lever  16  upwardly away from the push handle assembly  15  results in a lateral movement of the shift collar  37  to disengage the cam follower  39  from the cam member  40 , thereby disengaging the drive mechanism  30  into an inoperative configuration. 
     In operation, the operator would fill the hopper  20  with a supply of compost and push the apparatus  10  into position where a topdressing of compost on the ground is desired. By grasping the handle  15 , the operator can provide the power to move the apparatus  10  over the surface of the ground and to change the direction of travel of the apparatus  10 . Once the apparatus is positioned at the desired location, the operator pulls down the activation lever  16  to shift the rocker weld assembly  35  laterally so that the cam follower  39  mounted on the rocker member  36  can engage the cam member  40 . If the cam member  40  is oriented in a manner that would block the shifting of the rocker weld assembly  35 , the operator will need to move the apparatus  10  slightly to re-orient the cam member  40 , which is fixed to and rotates with the drive axle  32  which is secured to the drive wheel  12   a.    
     With the drive mechanism  30  engaged, the operator pushes the handle  15 , and thus the apparatus  10 , over the surface of the ground over which the topdressing of compost is desired. When the apparatus  10  becomes positioned over a portion of the ground where the topdressing of compost is not desired, the activation lever  16  is raised to disengage the drive mechanism  30  by shifting the rocker weld assembly  35  laterally such that the cam follower  39  is spaced from the cam member  40 . With the drive mechanism  30  engaged, the rotation of the drive wheel  12   a  turns the cam member  40  whereby the machined groove in the cam member  40  provides a surface over which the cam follower  39  moves to oscillate the rocker members  36  longitudinally. The longitudinal movement of the rocker members  36  pushes and pulls on the drive arms  42  connected to the movable screen  25  causing the longitudinal reciprocal movement of the movable screen  25  over the top of the stationary screen  23 . The reciprocal movement of the upper screen  25  creates a sifting action on the compost material and reduces particle size of the compost material until the compost falls through the screens  23 ,  25  and onto the surface of the ground. 
     Furthermore, the reciprocating motion of the drive mechanism  30  and the movable screen  25  creates sufficient vibration that, along with the vertically oriented sides  21  of the hopper  20 , prevents the compost material from bridging within the hopper  20 . Preferably, the stationary and movable screens  23 ,  25  are formed from expanded metal formation techniques; however, the screens could also be formed of sheet metal with pre-punched holes, or plastic screens, which would still allow the passage of compost particles through the screen members  23 ,  25  when the reciprocating shuttling of the movable screen  25  is accomplished. The weight of the apparatus  10  with the hopper  20  completely loaded with compost material is a significant factor in the design and manufacture of the apparatus  10  as the total weight must not be too great to enable the operator to manually move the apparatus  10  over the surface of the ground. 
     It will be understood that changes in the details, materials, steps and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiments of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention. 
     In the way of an example, one skilled in the art would recognize that the removal of the handle assembly  15  and substituting therefor a hitch mechanism (not shown) would enable the compost spreading apparatus  10  to be connected to a prime mover, such as a lawn tractor or ATV, and operated as a pull-type implement. 
     As a further example, the apparatus  10 , including the stationary and movable screens  23 ,  25  can be utilized with a supplemental spreading device (not shown) wherein the apparatus  10  would break up and dispense compost through the screens  23 ,  25  onto the spreading device that would then discharge the dispensed compost over the ground in a swath that can be substantially wider than the apparatus  10 . The drive for the movable screen  25  and for the spreading device can be provided as a ground drive in the substantially the same manner as described above.