US3559805A - Stone and rock removing device - Google Patents

Abstract

A device for removing stones and rocks intermixed with harvested potatoes comprising a conveyor for receiving and conveying same one by one in contiguous relationship with a sensor transmitting mechanical vibrations whereof those vibrations caused by a stone or rock exceed a predetermined level and whereby such discrete vibrations are converted by a crystal pickup to signal voltages and in conjunction with circuit means therefor energize a solenoid operatively connected to a valve to effect communication from a pneumatic source to an air cylinder to reciprocate a plunger ram to eject such stone or rock.

Description

United States latei [72] Inventors Richard Nelson Cragg, deceased Cohocton, N.Y.; Patricia A. Cragg, Administratrix; William E. Cragg, Administrator [21 Appl. No. 742,042

[22] Filed July 2, 1968 [45] Patented Feb. 2, 197] [54] STONE AND ROCK REMOVING DEVICE l9 Claims, 11 Drawing Figs.

52 use: v. 209 73,

209/82 511 lnt.Cl 1mm 5 54 501 FieldoiSearch ..209 s2,73,

[56] References Cited UNITED STATES PATENTS 2,712,753 7/1955 Campbell 324/80X 3,435,950 4/1969 Suverkrop 209/1 1 1.9X

Primary Examiner-Allen N. Knowles AtI0mey-Lowe and King ABSTRACT: A device for removing stones and rocks intermixed with harvested potatoes comprising a conveyor for receiving and conveying same one by one in contiguous relationship with a sensor transmitting mechanical vibrations whereof those vibrations caused by a stone or rock exceed a predetennined level and whereby such discrete vibrations are converted by a crystal pickup to signal voltages and in conjunction with circuit means therefor energize a solenoid operatively connected to a valve to efiect communication from a pneumatic source to an air cylinder to reciprocate a plunger ram to eject such stone or rock.

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STONE AND ROCK REMOVING DEVICE The present invention generally relates to separating apparatus, and in particular to agricultural separating apparatus utilizing mechanical sensing means wherein harvested crop and foreign object mixtures are transported past density responsive sensing means, and control signals are generated to eject the foreign objects from the mixture.

The problem of the art to which this invention apertains is the need for a stone and rock removing device which will function and operate economically to remove stones and rocks intermixed with harvested potatoes. The potato, as one of the world s most valued and widely grown vegetables, grows 4 in relatively poor soil with little attention. Upon harvesting potatoes grown in soil containing stones and rocks, the stones and rocks are harvested along with the potatoes. This described situation requires the expenditure of time, money and effort in removing the stones and rocks from the harvested potatoesusually by hand. The increasing cost factor of labor necessary to remove the intermixed stones and rocks from the harvested potatoes grown in such soil militates against such growing of potatoes. With such increasing cost factor of labor, it becomes increasingly uneconomic to grow and harvest potatoes in marginal soil having stones and rocks.

According to the present invention, an agricultural separating apparatus for sorting foreign objects such as stones and rocks from harvested crops, such as potatoes, comprises a conveyor for receiving and transporting the intermixed foreign objects and harvested crops in one-by-one seriatim fashion. The sensing means are positioned beside the conveyor so as to have a contiguous relationship with the intermixed foreign objects and harvested crops. The sensor means is responsive to the differences in density or momentum between the foreign objects and harvested crops as they are transported along the conveyor; the sensor means generates pickup signals indicative of these differences. Control means receive the pickup signals generated by the sensor and control ejecting means such as a plunger ram to eject the foreign objects from the intennixture.

A feature of this invention is that sorting apparatus transports an intennixture of objects to be sorted past sensing means in one-by-one seriatim and contiguous fashion. The sensing means is responsive to the physical property of density or to the momentum of the intermixed objects, and generates signals in response thereto. Certain of the intermixed objects, i.e., rocks and stones, will have a large enough density such that the signal generated by the sensor will activate control means to cause ejection of those objects from the mixture.

It is, accordingly, an object of the present invention to provide a new and improved agricultural separating apparatus for removing foreign objects from harvested crops.

Another object of the present invention is to provide an agricultural separating apparatus for automatically removing foreign objects such as stones and rocks from harvested crops.

Another object of the invention is to provide a new and improved agricultural separating apparatus for sorting foreign objects and harvested crops, and operating on the physical property of densities of the intermixed objects.

Another object of the invention is to provide a new and improved agricultural separating device wherein every object to be sorted by the device contacts a sensor.

This object and other objects of the invention should be discerned and appreciated from the detailed specification taken in conjunction with the drawings, wherein like reference numerals refer'to similar parts throughout the several views, in which:

FIG. 1 is an elevation view of the device showing potatoes being collected in a collecting bin;

FIG. 2 is an end view of the device in the direction of the arrow 2"ofFlG. 1;

FIG. 3 is a perspective view of the device;

FIG. 4 is a perspective view of the sensor and the box housing the crystal pickup;

FIG. 5 is a representation of the topology of the circuit utilized in the invention;

FIG. 6 is a block diagram representing the subfunctions of the electrical circuit;

FIG. 7 is a representation of the AC signal voltage generated by the crystal pickup;

FIG. 8 is a representation of the signal voltage of FIG. 7 as amplified by the amplifier stage;

FIG. 9 is a representation of the amplified signal voltage of FIG. 8 as rectified by the rectifier stage;

FIG. 10 is a representation of the rectified signal voltage of FIG. 9 as sensed by the detector in excess of the detect level causing the electronic switch to operate;

FIG. 11 is a representation of the relay or solenoid energized by the electronic switch characterized in FIG. 10.

Reference is now made to FIGS. 1, 2 and 3 wherein numeral I generally refers to the invention of the stone and rock removing device. Harvested potatoes containing intermixed stones and rocks 3 are shown carried on a conveyor belt 5 of a conventional potato harvester. These harvested potatoes 3 are deposited upon the conveyor belt 7 of the invention.

The conveyor incorporated in the device is of the gravitydischarge type. Its continuous conveyor belt 7 is trained around idler pulley 9 and driven pulley 1 1. Driven pulley I1 is fixed to common shaft 13 to which driven pulley 15 is corotatably mounted. Drive is imparted to driven pulley 15 by means of drive motor 17 having a drive pulley 19 fixedly mounted on its drive shaft with a V-pulley belt 21 trained over the driven pulley 15 and drive pulley 19.

Frame 23 slidably mounts a plate 25 on each side of the idler pulley 9. Each plate 25 journals the end of the shaft carrying the idler pulley 9. Each plate 25 is adjustably movable in a horizontal direction, as viewed in FIG. 1, by tightening or loosening of nut 27 on screw rod 29 fixed to plate 25. Plates 25 with their associated nuts 27 and screw rods 29 function with respect to frame 23 as a pulley tightener for conveyor belt 7 by appropriate tightening of nuts 27.

Common shaft 13 is mounted in bearing 31 upstanding from frame 23 and joumaled in journals 33 and 35 upstanding from frame 23.

As viewed in FIG. 1, the legs depending from the left side of frame 23 are relatively higher than the legs depending from the right side of frame 23 such that the conveyor of the device with its associated conveyor belt 7 will function and operate as a gravity-discharge type of conveyor in order that potatoes deposited and conveyed on the conveyor belt 7 from the left side to the right side will fall by gravity into the collecting bin 37.

As viewed in FIG. 2, the leg 39 depending from the right side of frame 23 is higher than leg 41 depending from the left side of frame 23 in order that the potatoes, stones and rocks being conveyed on conveyor belt 7 will be constrained by gravity to be carried therealong in abutting and guiding relationship by back wall 43 upstanding from guide plate 45 carried on frame 23.

As shown, guide plate 45 is substantially of L-shaped configuration with its bottom plate 47 disposed horizontally and backwall 43 disposed vertically. Backwall 43 has a section 49 articulated angularly. with respect to backwall 43. The terminal end portion 51 of this articulated section 49 is arranged and constructed to be disposed in proximal relationship with the sensor 53 of crystal pickup 55 (FIG. 4) housed in box 57 containing insulation 59 for vibration dampening.

Bottom plate 47 mounts box 57, as shown. Carried beneath bottom plate 47, as shown, is box 61 which houses the electrical components of the invention. Carried on bottom plate 47, as shown, is a common commercial pneumatic valve 63. Mounted on bottom plate 47 by U bolts 65, as shown, is the air cylinder 67.

Pneumatic valve 63 is of the common commercial type such as the Versa valve, Model No. FSG-4322, manufactured by Versa Products Co., Inc., Coolidge Avenue, Englewood, New Jersey. Valve 63 comprises a solenoid or relay 69 whose armature is compression-spring biased foi' return upon deenergization, a valve body 71 whose two-way piston is operatively connected for reciprocation to the solenoid armature, an intake port 73 in communication with a pneumatic source (not shown) by air hose connection 75, and two outlet ports 77 and 79 communicating by respective air hoses 81 and 83 to respective inlet ports 85 and 87 of air cylinder 67. Air cylinder 67 has a plunger ram 89 operatively connected to a two-way piston housed within air cylinder 67.

When solenoid 69 is energized, communication with the pneumatic source is established to intake port 73, through the left side of the two-way piston in valve body 71 as viewed in FIG. 3, to outlet port 77, through air hose 8], to inlet port 87, thereby reciprocating the two-way piston of the air cylinder 67 outwardly with plunger ram 89 ejecting from conveyor belt 7 any stone or rock which at the instant of activation of ram 89 is in front of ram 89. The outward position of plunger ram 89 is shown by dashed lines in FIGS. 2 and 3. When solenoid 69 is deenergized, its operatively associated compression spring constrains the two-way piston of the valve body to its return reciprocating movement thusly establishing communication with the pneumatic source through the right side of the twoway piston in valve body 71 as viewed in FIG. 3, to outlet port 79, through air hose 83, to inlet port 89, thereby reciprocating the two-way piston of the air cylinder 67 inwardly with plunger ram 89 disposed in its retracted position shown by the solid lines in FIGS. 2 and 3. While solenoid 69 is deenergized, plunger ram 89 is maintained in its retracted position by the communication established with the pneumatic source, as described. It should further be appreciated that, whether in the operative or retracted position of plunger ram 89, the pressurized air from the pneumatic source is continuously being bled to atmosphere to facilitate the reciprocation of the air-cylinder piston in its operative and retracted movements.

It should further be appreciated that the described gravitydischarge type of conveyor of the invention, along with the described tilted conveyor belt 7, arranged and constructed with the backwall 43 and its angularly articulated section 49, cooperatively functions to convey potatoes, stones and rocks one at a time in contiguous, touching relationship with sensor 53 thereby imparting mechanical vibration signals to sensor 53.

inasmuch as the stones and rocks have a greater density and hardness than potatoes, a different mechanical vibration is imparted to the sensor 53 when same is struck or touched by stones and rocks as compared to potatoes. These mechanical vibration signals are in turn transmitted to the crystal pickup for conversion into voltage signals by the transducer function of the pickup. The crystal pickup 55 is covered with a plastic material to insulate it against other than the discrete mechanical vibrations transmitted by the sensor 53. The insulation 59 in box 57 additionally provides protection against jarring or external vibrations that might be transmitted to the crystal pickup 55 and likewise serves to attenuate such externally transmitted vibrations such as through frame 23.

The function of the electrical circuit is to energize solenoid or relay 69 whenever discrete mechanical vibrations imparted to sensor 53 and transmitted to crystal pickup 55 in turn generate AC signal voltages which exceed a predetermined level.

The subfunctions of the electrical circuit are represented in FIG. 6. The AC signal voltage generated by crystal pickup 55 is represented by FIG. 7. The subfunction of the amplifier of increasing or amplifying the AC signal voltage generated by the crystal pickup to a higher amplitude is represented by FIG. 8. The subfunction of the rectifier is to cause the AC portion of the voltage to be all on the same side with reference to the initial DC level and is represented in FIG. 9. The subfunction of the detector is to sense only that portion of the signal voltage that exceeds the detect level and will cause the electronic switch to operate, and is represented in FIG. 10. The subfunc tion of the electronic switch, in turn, is to cause the solenoid or relay 69 to energize and is represented in FIG. ll.

The topology of the circuit used in this invention is shown in FIG. 5. Crystal pickup 55 generates the AC signal voltage which is coupled by the capacitor 91 to the first amplifier stage comprising resistor 93, resistor 95, transistor 97, resistor 99, resistor 10], transistor 103 and resistor 105. The first amplifier stage, in addition to amplifying the voltage, also provides an impedance match for the reason that this configuration has a high input impedance and a low output impedance. Capacitor I07 couples the AC portion of the voltage from the first to the second amplifier stage. The second amplifier stage comprises resistor 109, resistor 111, resistor 113, transistor 115, resistor 117, transistor 119, resistor l2], transistor 123 and resistor 125. Two stages of amplification are required to achieve the level of amplification that isnecessary. Capacitor 127, connected across the 12 volt power source 129 between the first and second amplifier stages, as shown, functions to prevent feedback by filtering the power supply voltage. Capacitor 131 couples the AC portion of the voltage from the amplifier to the rectifier comprising transistor 133 and resistor 135. Transistor 133 is connected in a manner that operates exactly the same as a diode by allowing current to pass in only one direction and thereby allowing only a negative voltage that is proportional to the signal voltage to appear at the junction of transistor 133 and resistor 135. A diode can be used in place of transistor 133 if desired. The detect circuit comprises resistor 137 and potentiometer 139, in conjunction with resistor 141 and transistor 143. Potentiometer 139 is a variable resistor that can control the detect level for optimum operation. The electronic switch comprises transistor 143, resistor 145 and transistor 1'47. Transistor 143 is normally in saturation. A negative going voltage at the base of transistor 143 will cause it to cutoff. When transistor 143 cuts off, the collector goes positive and causes the transistor to go from a cutofi condition to a saturated condition, which, in turn, causes relay or solenoid 69 to become energized. Capacitor 149 isused to store energy in order to prevent relay 69 from chattering.

Potentiometer 139 permits circuit tuning to allow mechanical vibrations from stones or rocks of a predetermined level, converted into electrical signals, to pass through the circuit to energize solenoid 69. The device may be utilized to separate stones and rocks intermixed with harvested beets, onions, etc.

From the description of the construction, function and operation of the various components of the invention, it should be appreciated that the speed at which conveyor belt 7 is driven, and the proximal relationship of the terminal end portion 51 of section 49, sensor 53 and ram 89, and the timed sequence of ejection and retraction of ram 89 controlled by the electrical circuit, are necessarily of a mutually dependent relationship that, as individual potatoes, stones or rocks are being conveyed one by one along and up section 49, the sequential action of ejection and retraction of ram 89 will be practically instantaneous to eject a stone or rock and then retract so as not to interfere with an immediately following potato; moreover, the necessity of instantaneous recycling of the ram 89 should be obvious in the situation of another immediately following stone or rock.

There has been disclosed a new and improved agricultural separating apparatus useful for separating foreign objects such as stones and rocks from harvested crops such as potatoes, beets and onions, for example. The invention operates on the principle of transporting an interrnixture of the foreign objects and harvested crops in a one-by-one seriatim fashion past a contiguous physical property sensor responsive to the density of the intermixed objects. The sensor operates to generate activating signals indicative of the higher density objects such as rocks and stones while permitting the harvested crops to pass through without generating such an activating signal. The activating signal is utilized to energize an ejecting mechanism to separate those foreign objects from the intermixture.

While there has been described and illustrated one specific embodiment of the invention, it will be clear that variations of the details of construction which are specifically illustrated and described may be made without department from the true spirit and scope of the invention as defined in the appended claims.

lclaim:

l, A device for removing stones and rocks intermixed with harvested potatoes; said device comprising a conveyor, sensor means, control means and a plunger ram; said conveyor receiving and conveying the intermixed stones, rocks and potatoes by said sensor in a one-by-one contiguous relationship with said sensor means, said sensor means, generating pickup signals proportional to the density of each stone, rock and potato touching said sensor means and transmitting said pickup signals to said control means, said control means controlling the operation of said plunger ram, and said plunger ram ejecting said stones and rocks.

2. A device for removing stones and rocks intermixed with harvested potatoes in accordance with claim I, wherein said conveyor further comprises a backwall and an angularly articulated section, wherein said backwall and articulated sectiori are vertically disposed relative to said conveyor, wherein said section is articulated angularly relative to said backwall, and wherein said backwall and articulated section cooperate to convey the potatoes, stones and rocks one by one by said sensor means.

3. A device for removing stones and rocks intermixed with harvested potatoes in accordance with claim 1, wherein said conveyor further comprises depending legs, a backwall and an angularly articulated section, wherein said depending legs are of such relative height to slope said conveyor downwardly toward its discharge end, wherein said backwall and articulated section are vertically disposed relative to said conveyor, wherein said section is articulated angularly relative to said backwall, wherein said depending legs further are of such relative height to tilt said conveyor relative to said backwall, thereby cooperating to convey the potatoes, stones and rocks one by one by said sensor means.

4. A device for removing stones and rocks intermixed with harvested potatoes in accordance with claim 1, wherein said conveyor further comprises a backwall and an angularly articulated section, wherein said backwall and articulated section are vertically disposed relative to said conveyor, wherein said section is articulated angularly relative to said backwall, wherein said articulated section has a terminal end portion, and wherein said terminal end portion, sensor means and plunger ram are in such proximal relationship that said plunger ram effects instantaneous ejection of a stone or rock touching or striking said sensor means.

5. A device for removing stones and rocks intermixed with harvested potatoes in accordance with claim 1, wherein said conveyor further comprises depending legs, a backwall and an angularly articulated section, wherein said depending legs are of such relative height to slope said conveyor downwardly toward its discharge end, wherein said backwall and articulated section are vertically disposed relative to said conveyor, wherein said section is articulated angularly relative to said backwall, wherein said depending legs further are of such relative height to tilt said conveyor relative to said backwall, thereby cooperating to convey the potatoes, stones and rocks one by one by said sensor means; wherein said articulated section has a terminal end portion, and wherein said terminal end portion, sensor means and plunger ram are in such proximal relationship that said plunger ram effects instantaneous ejection of a stone or rock touching or striking said sensor means.

6. A device for removing stones and rocks intermixed with harvested potatoes in accordance with claim 1, wherein said control means further comprises circuit means, a solenoid, pneumatic source and air cylinder, wherein said circuit means converts discrete transmitted vibrations into electrical signals to energize said solenoid, whereimsaid solenoid operatively establishes communication from said pneumatic source to said air cylinder, wherein said air cylinder has a piston, and wherein said air cylinder piston is operatively connected to said plunger ram.

7. A device for removing stones and rocks intermixed with harvested potatoes in accordance with claim I, wherein said control means further comprises circuit means, a solenoid, pneumatic valve, pneumatic source and air cylinder, wherein said circuit means converts discrete transmitted vibrations into electrical signals to energize said solenoid, wherein said solenoid is operatively connected to said pneumatic valve to actuate same, wherein said pneumatic valve has communication from said pneumatic source to said air cylinder, wherein said air cylinder has a piston, and wherein said piston is operatively connected to said plunger ram.

8. A device for removing stones and rocks intermixed with harvested potatoes in accordance with claim 1, wherein said conveyor further comprises a backwall and an angularly articulated section, wherein said backwall and articulated section are vertically disposed relative to said conveyor, wherein said section is articulated angularly relative to said backwall, and wherein said backwall and articulated section cooperate to convey the potatoes, stones and rocks one by one by said sensor means; wherein said control means further comprises circuit means, a solenoid, pneumatic source and air cylinder, wherein said circuit means converts discrete transmitted vibrations into electrical signals to energize said solenoid, wherein said solenoid operatively establishes communication from said pneumatic source to said air cylinder, wherein said air cylinder has a piston, and wherein said air cylinder piston is operatively connected to said plunger ram.

9. A device for removing stones and rocks intermixed with harvested potatoes in accordance with claim I, wherein said' conveyor further comprises depending legs, a backwall and an angularly articulated section, wherein said depending legs are of such relative height to slope said conveyor downwardly toward its discharge end, wherein said backwall and articulated section are vertically disposed relative to said conveyor, wherein said depending legs further are of such relative height to tilt said conveyor relative to said backwall, thereby cooperating to convey the potatoes, stones and rocks one by one by said sensor means; wherein said control means further comprises circuit means, a solenoid, pneumatic valve, pneumatic source and air cylinder, wherein said circuit means converts discrete transmitted vibrations into electrical signals to energize said solenoid, wherein said solenoid is operatively connected to said pneumatic valve to actuate same, wherein said pneumatic valve has communication from said pneumatic source to said air cylinder, wherein said air cylinder has a piston, and wherein said piston is operatively connected to said plunger ram.

10. A device for removing stones and rocks intermixed with harvested potatoes in accordance with claim 1, wherein said conveyor further comprises depending legs, a backwall and an angularly articulated section, wherein said depending legs are of such relative height to slope said conveyor downwardly toward its discharge end, wherein said backwall and articulated section are vertically disposed relative to said conveyor, wherein said section is articulated angularly relative to said backwall, wherein said depending legs further are of such relative height to tilt said conveyor relative to said backwall, thereby cooperating to convey the potatoes, stones and rocks one by one by said sensor means; wherein said articulated section has a terminal end portion, and wherein said terminal end portion, sensor and plunger ram are in such proximal relationship that said plunger ram effects instantaneous ejection of a stone or rock touching'or striking said sensor means; wherein said control means further comprises circuit means, a solenoid, pneumatic valve, pneumatic source and air cylinder, wherein said circuit means converts discrete transmitted vibrations into electrical signals to energize said solenoid, wherein said solenoid is operatively connected to said pneumatic valve to actuate same, wherein said pneumatic valve has communication from said pneumatic source to said air cylinder, wherein said air cylinder has a piston, and wherein said piston is operatively connected to said plunger ram.

11. A harvesting device for density sorting an intennixture of foreign objects and harvested crops comprising sensing means for generating control signals indicative of the density of each said foreign object and crop in said intermixture, means for transporting said foreign objects and crops in a oneby-one sen'atim and contiguous .fashion past said sensing means, and means actuated by said control signals and capable of distinguishing between control signals indicative of said foreign objects and said crops for ejecting said foreign objects from said intermixture.

[2. The process of density sorting harvested crops from an intermixture of foreign objects and harvested crops comprising the steps of transporting said intermixture in a one-by-one seriatim fashion past a sensor. contacting said sensor with each foreign object and harvested crop in said intermixture, generating a control signal proportional to the density of each foreign object and crop in said intennixture, and actuating a sorting mechanism with said control signals generated when said objects contact said sensor whereby said foreign objects are sorted from said intcrmixture.

13. The harvesting device of claim 11 wherein said sensing means comprises a crystal pickup device having a sensor arm which is contacted by each foreign object and harvested crop in said intermixture.

14. The harvesting device of claim 13 wherein said sensing means further comprises a plurality of crystal pickup devices having sensor arms. and said intermixture is transported in a plurality of one-by-one seriatim contiguous relationships past said sensing means.

15. The device of claim 1 wherein said sensor means comprises a crystal pickup device having a sensor arm which is contacted by each stone, rock and potato in said intcrmixture.

16. The device of claim 1 wherein said sensing means further comprises a plurality of crystal pickup devices having sensor arms, and said intermixturc is transported in a plurality of onc-by-one seriatim contiguous relationships past said sensing means.

17. The device according to claim 1 wherein said control means comprise an amplitude discriminator.

18. The harvesting device of claim 11 wherein said means for ejecting said foreign objects from said intermixture comprises an amplitude discriminator.

19. The harvesting device of claim 11 wherein said means for ejecting said foreign objects from said intermixture further comprises a plunger ram.

Claims (19)

1. A device for removing stones and rocks intermixed with harvested potatoes; said device comprising a conveyor, sensor means, control means and a plunger ram; said conveyor receiving and conveying the intermixed stones, rocks and potatoes by said sensor in a one-by-one contiguous relationship with said sensor means, said sensor means, generating pickup signals proportional to the density of each stone, rock and potato touching said sensor means and transmitting said pickup signals to said control means, said control means controlling the operation of said plunger ram, and said plunger ram ejecting said stones and rocks.

2. A device for removing stones and rocks intermixed with harvested potatoes in accordance with claim 1, wherein said conveyor further comprises a backwall and an angularly articulated section, wherein said backwall and articulated section are vertically disposed relative to said conveyor, wherein said section is articulated angularly relative to said backwall, and wherein said backwall and articulated section cooperate to convey the potatoes, stones and rocks one by one by said sensor means.

3. A device for removing stones and rocks intermixed with harvested potatoes in accordance with claim 1, wherein said conveyor further comprises depending legs, a backwall and an angularly articulated section, wherein said depending legs are of such relative height to slope said conveyor downwardly toward its discharge end, wherein said backwall and articulated section are vertically disposed relative to said conveyor, wherein said section is articulated angularly relative to said backwall, wherein said depending legs further are of such relative height to tilt said conveyor relative to said backwall, thereby cooperating to convey the potatoes, stones and rocks one by one by said sensor meanS.

4. A device for removing stones and rocks intermixed with harvested potatoes in accordance with claim 1, wherein said conveyor further comprises a backwall and an angularly articulated section, wherein said backwall and articulated section are vertically disposed relative to said conveyor, wherein said section is articulated angularly relative to said backwall, wherein said articulated section has a terminal end portion, and wherein said terminal end portion, sensor means and plunger ram are in such proximal relationship that said plunger ram effects instantaneous ejection of a stone or rock touching or striking said sensor means.

5. A device for removing stones and rocks intermixed with harvested potatoes in accordance with claim 1, wherein said conveyor further comprises depending legs, a backwall and an angularly articulated section, wherein said depending legs are of such relative height to slope said conveyor downwardly toward its discharge end, wherein said backwall and articulated section are vertically disposed relative to said conveyor, wherein said section is articulated angularly relative to said backwall, wherein said depending legs further are of such relative height to tilt said conveyor relative to said backwall, thereby cooperating to convey the potatoes, stones and rocks one by one by said sensor means; wherein said articulated section has a terminal end portion, and wherein said terminal end portion, sensor means and plunger ram are in such proximal relationship that said plunger ram effects instantaneous ejection of a stone or rock touching or striking said sensor means.

6. A device for removing stones and rocks intermixed with harvested potatoes in accordance with claim 1, wherein said control means further comprises circuit means, a solenoid, pneumatic source and air cylinder, wherein said circuit means converts discrete transmitted vibrations into electrical signals to energize said solenoid, wherein said solenoid operatively establishes communication from said pneumatic source to said air cylinder, wherein said air cylinder has a piston, and wherein said air cylinder piston is operatively connected to said plunger ram.

7. A device for removing stones and rocks intermixed with harvested potatoes in accordance with claim 1, wherein said control means further comprises circuit means, a solenoid, pneumatic valve, pneumatic source and air cylinder, wherein said circuit means converts discrete transmitted vibrations into electrical signals to energize said solenoid, wherein said solenoid is operatively connected to said pneumatic valve to actuate same, wherein said pneumatic valve has communication from said pneumatic source to said air cylinder, wherein said air cylinder has a piston, and wherein said piston is operatively connected to said plunger ram.

8. A device for removing stones and rocks intermixed with harvested potatoes in accordance with claim 1, wherein said conveyor further comprises a backwall and an angularly articulated section, wherein said backwall and articulated section are vertically disposed relative to said conveyor, wherein said section is articulated angularly relative to said backwall, and wherein said backwall and articulated section cooperate to convey the potatoes, stones and rocks one by one by said sensor means; wherein said control means further comprises circuit means, a solenoid, pneumatic source and air cylinder, wherein said circuit means converts discrete transmitted vibrations into electrical signals to energize said solenoid, wherein said solenoid operatively establishes communication from said pneumatic source to said air cylinder, wherein said air cylinder has a piston, and wherein said air cylinder piston is operatively connected to said plunger ram.

9. A device for removing stones and rocks intermixed with harvested potatoes in accordance with claim 1, wherein said conveyor further comprises depending legs, a backwall and an angularly articulated section, wherein said depending legs are of such Relative height to slope said conveyor downwardly toward its discharge end, wherein said backwall and articulated section are vertically disposed relative to said conveyor, wherein said depending legs further are of such relative height to tilt said conveyor relative to said backwall, thereby cooperating to convey the potatoes, stones and rocks one by one by said sensor means; wherein said control means further comprises circuit means, a solenoid, pneumatic valve, pneumatic source and air cylinder, wherein said circuit means converts discrete transmitted vibrations into electrical signals to energize said solenoid, wherein said solenoid is operatively connected to said pneumatic valve to actuate same, wherein said pneumatic valve has communication from said pneumatic source to said air cylinder, wherein said air cylinder has a piston, and wherein said piston is operatively connected to said plunger ram.

10. A device for removing stones and rocks intermixed with harvested potatoes in accordance with claim 1, wherein said conveyor further comprises depending legs, a backwall and an angularly articulated section, wherein said depending legs are of such relative height to slope said conveyor downwardly toward its discharge end, wherein said backwall and articulated section are vertically disposed relative to said conveyor, wherein said section is articulated angularly relative to said backwall, wherein said depending legs further are of such relative height to tilt said conveyor relative to said backwall, thereby cooperating to convey the potatoes, stones and rocks one by one by said sensor means; wherein said articulated section has a terminal end portion, and wherein said terminal end portion, sensor and plunger ram are in such proximal relationship that said plunger ram effects instantaneous ejection of a stone or rock touching or striking said sensor means; wherein said control means further comprises circuit means, a solenoid, pneumatic valve, pneumatic source and air cylinder, wherein said circuit means converts discrete transmitted vibrations into electrical signals to energize said solenoid, wherein said solenoid is operatively connected to said pneumatic valve to actuate same, wherein said pneumatic valve has communication from said pneumatic source to said air cylinder, wherein said air cylinder has a piston, and wherein said piston is operatively connected to said plunger ram.

11. A harvesting device for density sorting an intermixture of foreign objects and harvested crops comprising sensing means for generating control signals indicative of the density of each said foreign object and crop in said intermixture, means for transporting said foreign objects and crops in a one-by-one seriatim and contiguous fashion past said sensing means, and means actuated by said control signals and capable of distinguishing between control signals indicative of said foreign objects and said crops for ejecting said foreign objects from said intermixture.

12. The process of density sorting harvested crops from an intermixture of foreign objects and harvested crops comprising the steps of transporting said intermixture in a one-by-one seriatim fashion past a sensor, contacting said sensor with each foreign object and harvested crop in said intermixture, generating a control signal proportional to the density of each foreign object and crop in said intermixture, and actuating a sorting mechanism with said control signals generated when said objects contact said sensor whereby said foreign objects are sorted from said intermixture.

13. The harvesting device of claim 11 wherein said sensing means comprises a crystal pickup device having a sensor arm which is contacted by each foreign object and harvested crop in said intermixture.

14. The harvesting device of claim 13 wherein said sensing means further comprises a plurality of crystal pickup devices having sensor arms, and said intermixture is transported in a plurality of one-by-one seriatim contiguous relationships past said sensIng means.

15. The device of claim 1 wherein said sensor means comprises a crystal pickup device having a sensor arm which is contacted by each stone, rock and potato in said intermixture.

16. The device of claim 1 wherein said sensing means further comprises a plurality of crystal pickup devices having sensor arms, and said intermixture is transported in a plurality of one-by-one seriatim contiguous relationships past said sensing means.

17. The device according to claim 1 wherein said control means comprise an amplitude discriminator.

18. The harvesting device of claim 11 wherein said means for ejecting said foreign objects from said intermixture comprises an amplitude discriminator.

19. The harvesting device of claim 11 wherein said means for ejecting said foreign objects from said intermixture further comprises a plunger ram.

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