US2751831A - Soil pulverizers - Google Patents

Description

June 26, 1956 F. E. NULL son. PULVERIZERS 3 Sheets-Sheet l Filed June 4, 1953 INVEN TOR. &? 5. w

June 26, 1956 F. E. NULL SOIL PULVERIZERS 3 Sheets-Sheet 2 Filed June 4, 1955 June 26, 1 6 F. E. NULL 2,751,831

son. PULVERIZERS Filed June 4, 1953 3 Sheets-Sheet 3 $6105 03inch INVENTOR. l :g 4,60%. 9? 33 Xsac.

T 4 g orzzo g limited States Patent 2, ,31, SOIL PULVERIZERS Fay E. Null, Beaver-creek Township, Greene (lgpnty, Obi? Application June 4, 1953, Serial No. 359,490 3 Claims. (Cl. 97.210)

11 is among the b ct of t PI9 in estor is vide a soil pulverizer with rptating claws the]: pick up lumps of soil, and a slide guide to direct them against the blades of a high speed rotor. A

Another object of the present invention is to provide a soil pulverizer that picks up soil by rotary claws sufficiently close together and passing close enopgh to the base of a slide guide to reject the passage of larger stones against the blades of a high speed rotor.

Another object of the present invention is to provide a soil pulverizer with soil pickup claws that be defiected backward upon striking an obstruction such as a stone pressed against the base :of the slide guide, and will exert a component .of force to drive the stone away from the slide end.

Another object of the present inveuti gn is to provide a soil puiverizer with a soil pickup slide guide having a retractible base that upon pressure from an obstrgction such as a stone slides ,back, allowing small roller in the base of the guide to engage the obstrpct on with a low friction contact, so that said obs tru ction can readily be driven downward with respect to the end of the slide guide so that said roller can pass over the obstruetio n.

Another object of -the present invention is to provide a soil .pulverizer that will save po yer, by a slide guide for the soil delivered by a pickup rotor that fine soil to pass through a grating 01) its front; surfaee, but guides all lumps above a specified size to impact against the blades of a high speed rotor.

Another object of the present in vention is to provide a soii pulvs zs w t efiectebl soi Pi ker Elsi t at 1. 1 9 striking a large obstrp ction sueh as the top of a nearly buried boulder, produce lifting force that raises the front end of the pulyerizer, allowing the bettom f rpnt end of the pi p sl e u d o r ll we? th t ii i ss- Another object of the present invention is to provide a soil pulverizer that has a slide guide to direct the clods to be broken in a direction nearly oppoeite to that of the sh st M0? blade 9 t a thsrs st s s i impa t i h a s tha 1. eas the s s; P is- Another obiectof the present invention is to provide a soil pulverizer with a high speed rotor with blades that strike the clods on broad, flat sides, so that the clods are disintegrated by impact crushing which gives much finer soil particles than by cutting edges.

Objects and advantages other than those above set forth will be apparent to thoseskilled the art from the following description when read in connection with the accompanying drawings which illpstrate an embodiment of the invention in the form of a pulverizer tractor at taohrnent, in which:

Fig. l is a plan view of the pulverizer attachment with the top of the shield broken away.

Fig. 2 is a side elfivation illustrating the aetion of the major cfimp 'neuts in pulverizing the 'soil,.yvit h portions of the shield and frame removed to show the function of the pickup rotor and the high velocity impact rotor, with pat of the slide guide broken away to exhibit the passage of the finer soil'through the front grating surface, and with part of the pickup rotor removed to expose its support.

Fig. 3 is a vertical section along line 3-5 in Fig. l part of the soil pickup rotor removed, and some of the interior parts of the slide guide omitted for clarity.

Fig. 4 is an enlarged plan view of a claw and its mounting on the soil pickup rotor.

Fig. 5 is a vertical section along the line 575 in Fig. 4.

Figs. 6, 7, 8, 9, l0, and 11 are schematic views, illustratiiig the interaction of the pickup claws with the retractible plate at the lower end of the slide guide and the roller at the base of the slide, in swallowing small stones, rejecting larger stones, and riding over the tops .of boulders. The shield and one side disc of the pickup rotor have been removed for clarity.

Fig. 12 is an enlarged schematic of the main components of Fig. 3 with the addition of the retractible plate elements in the interior of the slide guide. It illustrates the construction and interacting functions of the pickup claws, the slide guide with retractible end plate and'roller, and the high speed impact rotor blades.

Fig. 13 is an enlarged plan view of the slide guide with part of the top surface broken away, to show portions of the end plate and retraction elements in the guide interior and the openings in the rear side for the exit of fine soil that slips through the grating surface in front.

Fig. 14 is a schematic illustration of the steps involved in the crushing impact of a clod with a high speed rotor blade.

Fig. 15 illustrates given conditions for the calculation for the duration time of the change in momentum of a clod colliding with .a high velocity rotor blade.

Fig. 16 is a diagram of the moments of force involved when the pulverizer is climbing over a stone.

Referring more particularly to the drawings by characters of reference, reference numeral 71 in Figs. 1 and 2, is the pulverizer frame attached pivotally to the tractor drive bars 16 by axle 17. Axle 17 mounts the pulleys 18 and 19 on hearing 20, Said pulley 18 being driven by belt 2; from a tractor power takeoff, and said pulley 19 d i ul e 2 0 h ft .23. w h oun P y 2 and 2 5 to respectively drive pulley 26 on the shaft 27 of the soil pickup rotor 28 at a low speed and pulley Q9 on shaft 30 of the high velocity impact rotor 31 at a high speed.

Fig. 2 shows the elaws 32 of the soil pickup rotor 28 scraping out small pockets of clods 33 which are carried over the plate 35 and directed by the sprface 3,6 of the slide guide 37. The tine soil 4} passes through the gratng surface 36 and out at the rear of the slide guide 37. At the top of the surface 36 the clods leave the claws 3.2 by centrifugal force as at 38 ina direction at only a small angle to the vertical, and impact against the heavy, fiat forged steel blades 39 of the high velocity impact rotor T e sle m v PP ith a v oc V1 s li with the rotor blades 3 moving down at a velocity V so that the relative velocity .of impact is approximately the sum of velocities V1 and Vg.

Ste i t col sio 9 t e sleds h ths est of high speed rotor 31 are illn .rated in Fig. 14. The top view shows a clod $3 striking the blade 39 of the high velocity rotor 31. As shown in the second view from the top the clod is shattered into fragments. Qn impact, each elemental mass of the clod egrperienees g. lerge change in momentum which produces a crushing force on s sh e eme ta v lume eate t an it mor a s nd, and the s d d s ?3I-" i. in o sm ll .fr sosat 4% which still have a high yelocity relative ,to blade 3?. These fragments it impact against the rotor blade 3% and are broken into smaller particles ii which have not yet attained the downward velocity of blade 39 and as shown in the bottom yiew are in turn broken apd swept dow a ea o b ad 9 a f tal t- Asa ex mple o t c ush n t mes mp ied r ct fie a ubic nc f l We in 0-07 l ns. l s 5 skim? in 15 ns a rot g ad? 1 .(illay we hs abss 3 137 lb. per cu. ft., or 137 lb. per cu. ft. divided by the 1728 cu. in. per cu. ft. gives 0.079 lb. per cu. in.) If the ends of the claws 32 move in a circle of 3 ft. circumference at 5 revolutions per sec. (300 R. F. M.), the clod would move upward at a velocity of 5 3=l5 ft. per see. If the blades 39 move in a circle 2 ft. in circumference at 30 revolutions per sec. (1800 R. P. M.), they would have a maximum downward velocity of 30 2=60 ft. per sec. The resultant relative velocity at impact would thus be 75 ft. per see. If for an order of magnitude calculation the velocity is assumed to decrease at a constant rate the equation, F=(Wt./g) (AV/t),' applies, where Wt. is the weight of the impacting mass, g is the acceleration of gravity, AV is the change in velocity, and t is the time in which the change in velocity occurs. Assume to be on the conservative side that a cubic inch clod has sufiicient compressibility to suffer a 5 percent or 0.05 inch compression before cracking. (in estimation of the duration of impact neglect the upward, velocity of the clod 33 which is small compared to the downward velocity of the blade 39, and is an unknown value depending upon the resistance of the clod to compression.) Then in the time the blade 39 moves clown 0.05 inch the clod will have suffered its maximum compressibility. it will then crack unless it is traveling downward with the same velocity as the blade. For the clod to be traveling downward at'the same velocity as the blade at this time, it must have lost its upward velocity of 15 ft. per sec., and gained a downward velocity of 60 ft. per sec. in the time for the blade to move down'0.05 inch.

Substitution in the above formula:

F=(Wt./g) X (AV/t) gives the crushing force F, where g=acceleration of gravity 32.2 ft. per sec.

AV=change in velocity=l5(60)=75 ft. per see.

:time for AV to occur. The maximum value for I is given by the time required for the blade to move down 0.05 inch, or t=(distance/velocity):(005/ 720) =6.94 l sec.

3.22X 6.94X 10 This gives a crushing pressure on the clod of 2660 lb. per square inch, or 383,000 lb. per square foot, which is many times as large as the pressure required to break the average clod.

A very hard clod is relatively brittle, would not have a compressibility as large as 5 percent, and if it did not break, would be stopped and acquire the rotor blade velocity in a considerably shorter time, with :1 correspondingly larger crushing force.

With the above high velocity impact all clods will shatter into fragments. The fragments wi l in turn collide with the high speed rotor blades 39 and become broken into still smaller particles. The resultant fine mulch will be driven downward against the rear top 40 of slide 37 as at 41 and out under shield 42 of Fig. 2. The depth guide 43 is adjustable in height for the desired depth of cut.

. Fig. 3 is a vertical section along the line 33 in Fig. 1. The blades 39 of rotor 31 are welded between the front and back discs 44 (see Fig. l) which are secured to axle 30 which turns in bearings 45. Said bearings 45 are mounted on supports 70 attached to the frame 71. The pickup rotor 28 has two discs 46 welded to axle 27 which turns in bearings 47 carried by support 48 attached to the frame 71. The claws 32 are, pivoted on axles 49 whichare secured between the discs 46 of rotor 28 as in Figs. 4 and 5. The springs 50 attached to the discs at points 51 force the back endsof claws 32 against rod stops 52- extending between the discs 46.

=2.66X 10 lb. 26601b.

As shown in enlarged detail in Figs. 4 and 5 the claws 32 are normally held in a radial position by the springs 50, and the rod stops 52 do not allow any forward motion of the claws 32 in the direction of rotation beyond the radial position, but said springs allow them to swing back from the radial position when they encounter an obstruction such as a stone. The claws 32 are made of forged, high strength, alloy steel to stand up under repeated scraping against stones. The pickup rotor 28 retates at a relatively low velocity, but at high enough speed to make the claws 32 self cleaning by centrifugal force. At this speed at a normal rate of tractor advance, each claw takes a bite which is only a small fraction of the depth of the curved cavity 53 between claw ends. The claws 32 thus literally claw out the soil from in front of the pickup rotor 28, and push it onto the slide guide 37 where the fine soil passes through but the clods are hurled at the high speed rotor 31.

The slide guide 37 is positioned by support 70, and support 54, Fig; 2, secured by crosstie 55 between support members 70 and 48. The retractible plate 35 and roller 56 are shown in enlarged detail in Figs. 12 and 13. The claws 32 scrape out small loads of fine soil and clods as at 57, and push it over the plate 35 and up the slide guide surface 36.' Due to centrifugal force the finer soil is pushed through the grating of surface 36 and at the top of the guide 37 as at 58, the clods 33 leave the claws 32 in a tangential course because of centrifugal force and collide against the high velocity impact rotor blades 39, the resulting fine particles 41 being hurled down the surface 40 of said slide guide 37. The plate 35 slides in the slot guides 59 on the side walls 60 of guide 37. Plate 35 is held in the position of Figs. 12 and 13, by springs 62 between lugs 63 and tab plates 61 attached to the upper end of said plate 35, said springs pulling said slide forward until stops 64 meet said slot guides 59. When the plate 35 meets a solid obstacle it slides back over roller 56 and under surface 36 of slide guide 37, allowing said roller 56 to meet the obstruction.

To make the pulverizer practical for use on stony ground it must be able to pass small stones through its parts without injury, reject larger stones, and to climb over still larger stones that cannot be displaced and driven down below the level of the guide 37. Figs. 6 through 11 illustrate the interaction of the retractible plate 35, the roller 56, and the deflectable claws 32 to In Fig. 6 the claw 32 accomplish the above results. has forced the small stone 65 against the plate 35 which has been driven back into the interior of the slide guide 37 so that said stone is engaged by the roller 56. Claw 32 has been deflected backward and the direction of the force exerted on said stone by said claw is shown by the vector P1. As P1 is well above the axle 61 of roller 56, said stone 65 is pushed on up the surface 36 of the slide guide 37 as in Fig. 7. Roller 56 rather than a sharp edge is used to engage stones driven against slide guide 37 by claws 32, because of its low coefficient of friction. Its rolling action greatly reduces the force required to move a small stone over it, or to reject a larger stone under it. The stone65 is not large enough to damage the'heavy, forged steel blade 39 of Fig. 12 against which it impacts; the stone 65 will be broken by the impact unless it is of the harder type. The fine particles 41 cushion the impact of small stones, propelled downward by rotor blades 39, upon the surface 40 of the slide 'stone 66 is now represented by vector P3 which passes close to the center line of roller 56 so that said stone 66 can not travel any appreciable distance farther forward.

As shown in Fig. 9 the upper part of stone 66 is swung toward the roller 56, and as it can not go further the claw 32 is deflected backward until it can pass over stone 66. The force exerted on said stone by claw 32 is now represented by vector P4 which is well below the axle 61 of roller 56, and said stone 66 is driven downward if the soil is soft. An equal and opposite force P4 is exerted by said stone on the claw 32. The system comprised by the claws 32, pickup rotor 28, and the frame 71 is acted upon by the external force P4 which has the vertical component P4" in Fig. 16. This vertical component P4 will lift the front end of the pulverizer frame 71 if its moment about axle 17 in Figs. 1 and 16, P4" r1, exceeds the downward moment, wt. (weight of pulverizer) Xrz, of the pulverizer center of gravity, C. G., about said axle at radius r2. If the ground is too hard for the stone 66 to be driven down into the soil, the system comprised by the claws 32, the pickup rotor 28, and attached pulverizer frame 71 is acted upon by the external force P4 due to the reaction of the stone and is lifted up about axle 17 to allow roller 56 to pass over said stone 66.

Fig. illustrates the performance of the pulverizer when it encounters a large stone 67. Said stone is too large to be moved so that the claws 32 of the pickup rotor 28 are deflected in a direction opposite to the direction of rotation of said rotor 28. The forces exerted by said stone 67 upon the claws 32 are represented by the vectors P5 and P6. Due to the stiffness of the springs 50, said upward forces P5 and Pa have a greater upward moment about axle 17, Fig. 1, than the downward moment of the center of gravity of the pulverizer about said axle, and the front end of the pulverizer 71 starts to swing upward about said axle 17. (The deflected claws 32 on the periphery of pickup rotor 28 are equivalent to heavy rubber tire treads on a tractor drive wheel in climbing over an obstruction.) Fig. 11 shows the pickup rotor 28 climbing over the top of stone 67, the deflected claws 32 reacting against said stone to produce the vectors P7, P8, P9 and P10 that lift up the front end of the pulverizer attachment, so that said plate 35 will be retracted on contact with the stone 67, and the roller 56 will ride over the top of said stone. The slide guide 37 extends back behind the high speed rotor 31 to protect it from impingement on the stone 67 when the pickup rotor 28 and the slide guide 37 come down on the far side of said stone.

When the pulverizer is used instead of conventional plowing, the power requirements are too great for a small garden tractor if the impact rotor 31 is run at high speed. For the plowing operation said impact rotor 31 is run at about the same speed as the pickup rotor 28. This produces a good preliminary working of the soil, but in general will not produce the fine soil mulch needed for small seeds. If the soil is processed after the equivalent to plowing operation with the impact rotor 31 at high velocity, a very fine seed bed is prepared. The grating surface 36 of the slide 37 allows the fine soil particles 41 to pass through and pass out at the rear of said guide 37. Only those particles larger than the grating gap size are directed upward for collision with the high speed impact rotor 31. This results in a marked saving of power, since eflective crushing and braking of the particles of a clod requires high velocity impact which imparts to the soil a kinetic energy corresponding to the velocity of the blades 39 of said rotor 31, and is directly proportional to the mass of soil to which the velocity is imparted. Thus, if two thirds of the soil is fine enough to pass through the grating of surface 36, and only onethird in the form of clods impacts against rotor 31, the horse power to operate said rotor 31 is approximately only one-third as much, The grating surface 36 thus makes possible a large saving in power, for after the initial plowing type of soil working, the largest power requirement is for the high velocity impact rotor.

It is claimed and desired to secure by Letters Patent:

1. In a soil pulverizer, the combination of, pickup means mounted on a rotor, a soil guide, said pickup means having small clearance with said soil guide, a soil pocket bounded by said guide and two adjacent, undeflected pickup means whose radial depth is small relative to the normal plowing depth, said pickup means being deflectable by a large stone in the opposite direction to the rotation of said rotor, a restoring means attached to each pickup means, said pickup means being able to raise said rotor and said soil guide to pass over a stone when said pickup means are deflected by an amount to shorten their effective radii by substantially the depth of said soil pocket, a retractible slide on the front end of said guide, a roller mounted on said guide behind said slide, said slide being retractible under the push of a stone of appreciable size until it is flush with said roller which has a low coeflicient of friction and can readily roll up the side of a large stone when assisted by the lift of deflected pickup means.

2. In a soil pulverizer, the combination of a soil guide, projections on a soil pickup rotor with a radial depth small compared to normal plowing depth, projection tips with a narrow clearance along said soil guide, said projections being deflectable backwards with respect to the direction of rotation of said rotor upon striking an obstacle such as a stone, a first restoring means that resists backward deflection of said projections and produces a downward force component by said projections on the obstruction causing the deflection, a retractible slide on the lower end of said soil guide, a roller mounted on said soil guide behind said slide, a second restoring force means that resists retraction of said slide, said roller having a low coeificient of friction in engagement of stones that have pushed back said slide under the force of said projections, and said deflected projections, capable of a vertical force component that can lift said rotor and guide, and a horizontal component that can pull said roller over said stones.

3. In a soil pulverizer, the combination of, a soil pickup rotor, a soil guide, claws pivotally mounted on said pickup rotor with a small clearance between adjacent claws, narrow tips on said claws positioned with respect to said soil guide for forming soil pockets too small for stones large enough to damage a high velocity impact rotor, restoring means attached to each claw that resists their backward deflection with respect to the direction of rotation of said rotor, said deflected claws exerting downward forces on stones in their path and producing lifting forces on said pickup rotor and soil guide, a slide retractible against restoring means on the bottom of said soil guide, a low coeflicient of friction roller mounted on said soil guide behind said slide that engages stones that push said slide backward behind said roller, said deflected claws coacting with said roller by lifting said pickup rotor and soil guide and propelling said roller up and over stones of appreciable size.

References Cited in the file of this patent UNITED STATES PATENTS 895,332 Von Bertouch Aug. 4, 1908 922,535 Smith May 25, 1909 1,233,442 Britton July 17, 1917 1,302,883 Tilbury May 6, 1919 1,611,919 Kilborn Dec. 28, 1926 1,850,357 Pitcher Mar. 22, 1932 2,007,646 Gilbertson July 9, 1935 2,368,331 Seaman Jan. 30, 1945 2,466,084 Davis Apr. 5, 1949 2,693,746 Klein Nov. 9, 1954 2,701,105 Edwards Feb. 1, 1955 FOREIGN PATENTS 602,061 Great Britain May 19, 1948

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