DEVELOPMENT OF A MECHANICAL CABBAGE HARVESTER By Mohammed Yousry Hamdy AN ABSTRACT Submitted to the Colleges of Agriculture and Engineering of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in ‘ Agricultural Engineering Department of Agricultural Engineering _ 1962 (1)4 ‘“ f’ f .1) ‘ . ' '_ I F; ._ . _. 1: (V ? ' Approved: 4".- //::’5 1/;- z‘; aw" , ‘ . ._,-'..’$t_5*"'aa¢" ' ”L“... , 1/“ q DEVELOPMENT OF A MECHANICAL CABBAGE HARVESTER By Mohammed Yousry Hamdy The objective of this investigation was to develop a mechanical cabbage (Brassica oleracea var. capitata) harvester utilizing some of the design principles of the Scott Viner beet harvester. The major conversion of the beet harvester to a cabbage harvester was accomplished at the Michigan State University Agricultural Engineering Laboratory under the supervision of Dr. B. A. Stout during the winter and Spring of 1961 before this research was started. The conversion primarily consisted of inverting the lifter shoe assembly and the drive sheaves. In this position the lifter shoes raised the cabbage heads and the belts grasped the cabbage plant by the root and elevated it to the trimming mechanism, which was a pair of revolving disc knives mounted on the shaft of the elevator belt sheaves. The belts retained a firm grip on the root as it passed through the cutting knives and discharged it behind the drive belt sheaves. The harvested head and loose leaves, in contact with a fast moving overhead belt, were pushed rearward onto an in- clined slowly-moving belt. The harvested head rolled down the incline to the elevator while the loose leaves were carried up the incline and dropped on the ground. The author's efforts were devoted primarily to improv- ing the pick-up mechanism. That was the major problem in the MOHAMMED YOUSRY HAMDY machine and numerous approaches to solve it were tried. Steel fingers on the lower sheaves of the lifter belts solved the alignment, feeding, and lifting problems. The cut roots presented a minor problem as they accumu- lated on the platform shielding the sheave driving mechanism. A paddle wheel of the proper dimensions moving at the proper Speed completely eliminated this problem. The quality of trimming the cabbage was improved to get a flush trim leaving one to three wrapper leaves on the head. This was accomplished by changing the geometry, sus- pension, and Speed of the overhead belt, together with the position of the adjustable guides located in front of the disc knives. Appreciable improvement was obtained when cabbage was uniformly picked by the sheave fingers. Physical measurements were made on cabbage to collect basic data needed to improve the performance of the machine. The vertical and horizontal forces required to remove the plant from the ground were measured. The gross weight of the plant, the weight of the center head, leaves, and roots were recorded. The alignment of the roots and the heads was estimated. The head size, root diameter, and plant stem length were also recorded. DEVELOPMENT OF A MECHANICAL-CABBAGE HARVESTER By Mohammed Yousry Hamdy A THESIS Submitted to the Colleges of Agriculture and Engineering of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in Agricultural Engineering Department of Agricultural Engineering 1962 (3 gooCA+ {?/? 1/412“;- ACKNOWLEDGMENTS The author wishes to acknowledge all those who have helped make this investigation possible, particularly Dr. B. A. Stout, major professor during the first nine months of his graduate studies for providing encouragement and guidance. (Because of Far East travels, Dr. Stout was absent during the final phases of this study.) The time, efforts, and suggestions of Dr. W. E. Buchele opened new horizons for investigation and improving the machine performance during the last two months of this investigation. The assistance and suggestions of Dr. S. K. Ries of the Department of Horticulture and Mr. Thomas Burenga and his staff made the investigation possible and the tests meaningful. Sincere thanks are due to Dr. F. H. Buelow and Dr. G. H. Martin, members of the Guidance Committee, for their many helpful suggestions. Credit Should be given to Messrs. James Cawood and Glenn Shiffer for their Sincere interest and assistance in advising the author in machine shop work. Appreciation is extended to Professors A. W. Farrall, M. L. Esmay, and J. S. Boyd and other department members who have contributed to the completion of the project. ii TABLE OF CONTENTS Chapter INTRODUCTION LITERATURE REVIEW PHYSICAL MEASUREMENTS Apparatus Results Discussion APPARATUS Description of the Machine Field Tests CONCLUSIONS RECOMMENDATIONS FOR FURTHER STUDY BIBLIOGRAPHY ‘ APPENDIX Appendix I Appendix II Appendix III iii Page 10 12 16 19 19 21 32 33 35 36 37 42 74 Figure 10 11 12 13 14 15 16 LIST OF FIGURES MSU experimental cabbage harvester in a field of head lettuce (1961) . . . . . . . . . . . Picking device of MSU. Experimental Harvester (1961) . . . . . . MSU experimental harvester showing the clean- ing belt and elevator (1961) . . . . . . . MSU experimental harvester showing lifter shoe assembly, disc knives, overhead belt, and gathering chain . . . . . . . . Measurement of the vertical pulling force of cabbage (1962) . . . . . . . . . . . . . . Measurement of the horizontal pulling force of cabbage (1962) . . . . . . Lifter shoes of test (5) showing plows and gathering bars . . . . . . . Lifter shoes of test (7) showing slides and curved shields . . . . . . . . . Lifter shoes of test (9) showing slides and curved plates . . . . Energized gathering device of test (13) Lifter Shoes of test (15) showing slides and the strong Shields . . . . _ . . . . Lifter shoes of test (17) and paddle wheel later mounted in test (19) . . . . . . . . The lifter shoes and paddle wheel of test (22) . . . . . . . . . . . . . . . . Damage of the paddle wheel and fittings because of no slip clutch (test 22) The cabbage harvester during operation Showing the paddle wheel Floating rubber tire to help lift the cabbage (test 25) . . . . . . iv Page 11 ll 44 44 46 46 50 50 56 56 59 59 Figure Page 17 Floating rigid paddle (test 27) . . . . . . . . 61 18 Floating flexible paddle with Slip clutch and rubber lining (test 28) . . . . . . . . . . 61 19 Lifter Shoes of test (29) showing the plow- ing edge . . . . . . 63 20 Lifter shoes of test (30), left Side runner removed to allow for the steel fingers . . . . . 63 21 Lifter shoes of test (31) showing the set of fingers on the top of the right sheave . . . 65 22 Sheet metal steep incline to drop the cut-Off roots . . . . . . . . . . . . . . . . . 65 23 Root-throwing paddle wheel . . . . . . . . . . . 67 24 The double—deck deflecting shield in operation . . . . . . . . . . . . . . . . . . . 67 25 The overhead belt showing its tapered entrance . . . . . . . . . . . . . . . . . . . . 69 26 Spring-loaded suSpension of the overhead belt . . . . . . . . . . . . . . . . . . . . . . 69 27 Spring-loaded SUSpension of the overhead belt, allowing wider swinging . . . . . . . . . 71 28 The cleaning belt and the deflecting shield of test (7) . . . . . . . . . . . . . . . . . . 71 i Velocity diagram of cabbage lifting . . . . . . 27 ii Forces acting on lifter assembly . . . . . . . . 27 N.B.: All negatives are filed at Michigan State University Photographic Laboratory. The information services file number is 621901. INTRODUCTION Cabbage, one of the important vegetable crops in the United States, is grown commercially in about thirty-four states. An average Of 130,000 acres was grown annually for fresh market in the ten-year period (1), 1950-59. The aver- age production from this acreage for the above period was one million tons. The annual farm value of the cabbage produced for the fresh market averaged 40 million dollars. An average of 14,000 acres was grown for sauerkraut during the same period with average production of 200,000 tons. The annual farm value of cabbage produced for sauer- kraut averages 2-1/2 million dollars. Cabbage is harvested by hand with little mechanical aid. In a study Of costs and returns in producing sauer- kraut at Cornell University (2), it was found that labor for hand harvesting costs about $31.59 per acre; the total grow— ing and harvesting costs were $142.12 per acre. The develop— ment of a mechanical cabbage harvester has become necessary for the survival of the sauerkraut grower because of the unreliable source and high cost of hand harvest labor. Cabbage production, and in particular that used for sauerkraut production, is not large in comparison to some (1) Numbers in parenthesis following names corre- Spond to references listed in the bibliography. l other vegetable crops. Farm machinery manufacturers have not been willing to undertake a development program for a cabbage harvester because of the limited potential market for a mechanical cabbage harvester. Because the producers of cabbage need a mechanical harvester, this development program was initiated in 1961 at Michigan State University and this thesis represents the author's participation in this program. LITERATURE REVIEW The most important work of direct concern to this re- search was done at the Michigan Agricultural Experiment Station under the name of ”Project 651 - Basic Principles of Harvesting." Stout reported (3) that the work was initiated in the Summer of 1960 by recording some physical measurements made on cabbage at the Turner farm located near Saginaw, Michigan. The same measurements were repeated in the Summer of 1961. Stout reported: Cabbage plants comprising twenty-head samples were randomly selected. A 100-pound capacity Spring Scale was fastened to the cabbage roots by means of an "S" hook. The plant was then pulled vertically from the ground and the scale indicator observed for its maximum reading. Other data taken included average root diameter, root length, head size, and head weight. The root diameter was measured at ground level. Root length represents the length of the underground main tap root not including the Small portion of that root extending above ground. Head weight represents the weight of the center head. The values reported were comparable to what was ob- tained by the author in the tests conducted at Michigan State University Horticulture Farm in the Summer Of 1962. In another part of his report, Stout said that the cabbage harvester was constructed at the Michigan State University Agricultural Engineering Laboratory during the Winter and Spring of 1961. The harvester was constructed by modifying a Scott Viner beet harvester (Figure 1). 3 Fig. 1. 1'. ‘ '~ I . " ‘flz.."“ 4‘. . . . MSU experimental cabbage harvester in field of head lettuce (1961). a .1 u . ,. s .' t . . 5“- “ 1,1,; xi" g ;.,.2’ ‘ 1. ‘ fi‘. ‘- i ‘5 . f ' . 9‘ u n 1‘ v . ‘ I ‘. ‘ .l!rhv ‘. '2 I f 3 .J ‘5 q The same machine was used by the author in his tests and will be described in more detail in the chapter on the apparatus. The lifting shoes were a pair of two small streamlined shields with a comparatively small area Sliding on the ground (Figure 2). They were not very successful in lifting the cabbage; they pushed it ahead of the machine in most of the tests. The cleaning device at the rear of the machine incorporated a wide, inclined belt placed perpendicular to the direction of travel and moved slowly upwards to the left (Figure 3). The harvested heads fell onto the belt and rOlled down the incline where they were carried away to the right by the elevator while the loose leaves were carried up the incline and dropped onto the ground at the left Side of the machine. The root removing device was composed of two main elements: a square roller placed behind the disc knives to knock the cut—off roots down and a gathering chain under the drive belt Sheaves (Figure 4) to drop them on the ground. The device was not sUccessful, however, because it reversed the direction of motion of the roots. The incoming roots obstructed the cut roots, collected and choked the machine blocking the movement of incoming cabbage plants. Stout presented also in his report an analysis of the economic feasibility of a mechanical cabbage harvester. In this analysis he considered two harvesters priced at $3,000 and $6,000, with a five-year useful life and 60 per cent field efficiency. He concluded that a cabbage harvester . ... L... a“: . .. .c‘u.m,n.2.. k.....\.._\.... 3 a...” ; fie. . .. 3.: a... .- . c ... . 3 an . . . r\ .. . .l. . v \ «w; afar. 22‘] ...n .. VB . 0......J.~\~ 3‘ re . . - $03.57) . I. .. \i “ ', '1 C...‘ .44. .1. .5. I l . L L. U: . I} . . V .1; . n . f D .7... I... 3 o N .01. .b l u 1 I c L. I . V. 3.- p \v 'V b I ~ m .4,» I‘\. .I. \e s w .504 ‘3." t“. could favorably compete with hand harvesting. A profit over hand harvest will be expected with a $3,000 harvester used on a fifty—acre farm or a $6,000 harvester used on a 250- acre farm. Another approach to mechanical harvesting of cabbage was made by Splinter and Wright at North Carolina State University. Their initial objective was to define the physical properties Of cabbage which they felt were pertinent in the design of a mechanical harvester. They started in the Summer of 1961 by making measurements of the following pro- perties: 1. Uniformity of heads. 2. Plant diameter. 3. Stem diameter. 4. Length of leaf stem (portion of stem where leaves are attached). 5. Force to cut stem (knife action). 6. Resistance to drop, etc. They Obtained more of the same measurements in the 1962 sea- Son and utilized the information of the previous year in the design of a field machine. The harvester was tractor— mounted. The cabbage heads were cut from the root by a band saw mechanism; the root or stalk of the cabbage plants were left in the ground. A conveyor system was used to convey cabbage to a cart. (No details regarding the operation of the machine were available at the time of writing this thesis.) Some work was also done by Holmes at the University of Florida, but it was concentrated on the mechanical aids for cabbage harvesting. A survey was conducted in April, 1962 by mailing questionnaires to sixteen leading sauerkraut packers. The objective of this survey was to find the practical answer to the following questions: 1. How Should the cabbage head be cut? Is the height Of cut critical? Is the angle of cut critical? - What size heads are preferred? Is dirt a problem? What kind of washing process is used? Is bruising a problem? What is the price paid to the grower? Is the cost of harvesting available? Answers received from eight companies can be summarized as follows: 1. The cabbage head should be cut as close to the base of the head as possible, with perhaps the outside wrapper leaves partially or wholly cut from the stem. The angle of cut should be as nearly square as possible so as to insure a good job of coring. A cabbage head weighing five pounds and up is generally preferred for kraut. Some surface dirt is not normally a problem, but any dirt that might get into the head would be a problem as the heads are not normally washed. Minor bruising is not too serious, but rough handling that would cause breakage or loosen— ing of leaves would result in more waste. Also, and eSpecially important, if the cab-' bage is stored any length Of time after it is harvested, rot would start in the bruised areas. The average price of cabbage runs between $10 to $15 per ton, delivered. Harvesting costs run about $1.50 to $2.50 per ton. PHYSICAL MEASUREMENTS A knowledge of the force needed to pull the cabbage plant vertically or horizontally from the ground is necessary for designing a mechanical cabbage harvester. The gross weight of the plant and the net weight of the head would help the designer eStimate the material handling arrangements for the different elements of the harvester. A knowledge Of the relative alignment of the plant root and plant head would help him evaluate the expected machine performance in the picking operation. The geo- metrical dimensions of the plant, such as the head Size, the stem length, and the root diameter are also important factors to be considered when designing the harvester or checking the physical dimensions of a commercial harvester to determine if it can be used in a particular area. The following information was obtained at the Horti- culture Farm for the dates shown: 1. Force required to pull the plant vertically from the ground. 2. Force required to pull the plant horizontally from the ground. Plant, gross weight. Head, net weight. LII->00 Root, gross weight. 6. Distance between the root and a thread ex- tended parallel and between the rows. 9 10 7. Distance between the head center and the same thread. 8. Head, mean diameter. 9. Root, mean diameter. 10. Stem length. 11. The average coefficient of friction between cabbage and some materials. Tests 6 and 7 were repeated more frequently as it was believed that the alignment of the roots and of the heads seriously affects the picking operation which was the major problem of the machine. Apparatus The forces required to remove the plant from the ground were measured by a simple apparatus mounted on the left side of a tractor (Figure 5). A rope wound on a hand- rotated shaft and having-the other end hooked to a lOO-pound capacity Spring balance was used to apply the pulling force. A system of pulleys served to double the spring balance capacity to indicate the extra high forces. The apparatus .was designed with a mechanical advantage of 15 to avoid operator fatigue from the repeated tests. A pair of clamps was attached to the movable pulley and could be securely locked around the heads. An arrangement to pull the plant horizontally was pro- vided by a vertical beam (hidden behind clamps in Figure 6) with a pulley freely mounted at its lower end such that it laid below the movable pulley and almost touched the soil surface. An S-shaped hook was placed around the stem and (33‘. age asurerr. .‘-‘x t' ). X ‘— (19o 3‘ t. cat's? V L ~21 nu r timer. 1‘. ."U z; 12 pulled by a rope fixed to the movable pulley assembly. The clamps were kept on the apparatus during this test as the Spring balance-was calibrated to give a zero reading at no load with the clamps attached. A 25-pound capacity table spring balance was calibrated and used to measure the gross weight of the plant and the net weight of the head. A 25-Ounce spring balance was used to weigh the roots after the soil was removed. A large caliper was built and used to measure the head diameter while a commercial one was used to measure the root diameter. The alignment of the roots was determined by stretching a string between two stakes placed at the mid- point between the rows and measuring the distance between the string and root Side and string and head center. A lO-pound Spring balance was calibrated and used to estimate the coefficient of friction between cabbage and some of the commonly used engineering materials. The balance was fastened with an”S" hook to the cabbage at a point close to the surface Of cOntact to prevent any rolling. The balance was then pulled and both the static and dynamic frictional forces were measured and recorded along with the head weight. Results The results of tests and physical measurements con- ducted On samples of cabbage from Michigan State.University Horticulture Farm are listed in Tables I, II, III, IVa, and IVb (Appendix I). The variety was Glory and planted on May 2, 1962. The tests were conducted between September 27 and October 7, 1962. 13 Table I lists the measurements made to investigate the alignment of the roots of five samples varying in size from 30 to 35 heads each. A statistical analysis was con— ducted on the samples, assuming that cabbage population is normally distributed around the mean (4). following: It yielded the Sample Sample Sample Sample Sample 1 2 3 4 5 Sample size (NO. Of heads) 35 35 29 31 33 Max. dist. to thread (in.) 21.5 22 21 22 24 Min. dist. to thread (in.) 16.5 15 l8 18 18 Mean dist. to thread (in.) 18.7 18.6 20.2 19.6 21.8 Max. deviation from mean (in.) 2.8 3.6 2.2 2.4 3.8 Standard deviation (in.) 1.09 1.25 0.72 1.12 1.62 95% of population is expected to lie within 12.2 12.52 $1.47 12.28 $3.3 A Similar analysis was made on the values listed in Table II giving the distance between the thread and the head. 14 II I Sample Sample Sample Sample Sample l 2 3 4 5 Sample size (No. of heads) 35 35 29 31 33 Max. dist. to thread (in.) 22 24 23 25 26 Min. dist. to thread (in.) 16 15 14 19 15 Mean dist. to thread (in.) 18.2 18.7 17.5 22.2 20.7 Max. deviation from mean (in.) 3.8 5.3 5.5 3.2 5.7 Standard deviation (in.) 1.38 2.56 1.96 1.92 2.78 95% of the population is expected to lie within (in.) 12.8 15.2 14.0 13.9 +5.6 The same analysis was repeated on the head Size, root diameter, and stem length which are listed in Table III. == Head Size Root Dia. Stem Length Sample Sample Sample Sample Sample Sample 1 2 1 2 l 2 Sample size (heads) 31 33 31 33 31 33 Max. value (in.) 11.5 11.5 1.2 1.2 3.6 4.0 Min. value (in.) 7 6 0.8 0.6 2.4 1.5 Mean value (in.) 8.5 8.2 0.95 0 98 2.74 2.62 Standard de— viation (in.) 0.95 1.4 0.1 0.16 0.3 0.6 Expected - limits for 90% of popu- 10.1 10.6 1.13 1.25 3.25 3.6 lation 6.9 5.9 0.78 0.71 2.23 1.6 15 A more simple analysis was conducted on the contents of Tables IVa and IVb: Forces to remove cabbage from the ground Vertical Force Horizontal Force (1b.) (1b.) Sample Sample Sample Sample 1 2 1 2 Sample Size (heads) 16 16 15 16 Maximum force (1 pound) 94 78 112 100 Minimum force (1 pound) 56 35 45 42 Average force (1 pound) 74 59 85 65 Weight percentage of plant elements Net Head Leaves Roots Sample Sample Sample Sample Sample Sample 1 2 l 2 1 2 Max. Percent. 74 83 38 38 10.6 11.5 Min. Percent. 55 54 20 9 6.9 6.5 Ave. Percent. 65 71 27 20 7 6 9 The results of the tests conducted to estimate the coefficient of friction between cabbage and some engineering materials can be summarized as follows: Static Dynamic Coefficient Coefficient Steel plates 0.52 0.47 Zinc-coated Steel plates 0.50 0.45 Paper (hard board) 0.62 0.57 Wood (rough) 0.65 0.60 Wood (finished) 0.48 0.43 16 Discussion In the alignment test we were actually interested in investigating how far and how frequently the cabbage roots and heads deviated from the virtual centerline of the row. The results of our investigation may be stated as follows: . . . 95% of the cabbage roots are expected to grow in a 5-inch wide band and 95% of the center of heads are expected to lie in a 10-inch wide band. The above statement depends to some extent on the type and make of the planter used to plant the cabbage, and on the surface and condition of the soil. But the proba- bility factors which determine in which direction the plant will grow are the major variables. The physical dimensions of the plant have a Smaller effect on the design of the machine. The maximum and mini— mum head size, root diameter, and stem length may suggest some of the plant criteria that the machine has to accommo- date. It is true that they will change from field to field depending on the variety planted, the plant Spacing, the soil, the moisture, the amount and kind of fertilizer used, the temperature, etc., but they will not change much in a Single field. Since the machine can be adjusted to handle one field condition, the analysis was presented together with the statistical inference to estimate how seriously these changes are in a single field. Tables IVa and IVb list the force required to remove the plant from the ground, either vertically or horizontally. The pairing technique was used in pulling the heads by both 17 methods to get a more accurate estimate of the ratio between them. This technique reduces the possibility of misleading results in case of any change in properties along the row from which the sample was taken. The magnitude of these forces varied over a relatively wide range, which was not un- expected. The conclusion of the test is as follows: The horizontal force required to remove the plant from the ground is about 10 per cent higher than the vertical force required to pull it from the ground. Combining this result with the estimated coefficients Of friction reveals one of the basic principles of mechanical harvesting of cabbage: Cabbage cannot be dragged out of the ground by a horizontal frictional force produced by a reaction on the rubbing surface equal to the force by which it is anchored in the ground. In fact, this frictional force will be less than half of the horizontal force required to pull the cabbage from the ground. However, it Should be stated that cabbage was freed horizontally from the ground in actual field tests due to direct mechanical push or due to the accumulation of soil ahead of the machine which released the plant before the machine touched it. The same tables also list the gross weight Of the plant and the weights of the head, leaves, and roots. The absolute values of these weights express the same concept of the plant dimensions as discussed previously, but the rela- tive values may Show a new concept which is important for the performance Of the machine. These relative values show the amount of material that must be handled by each machine 18 element. The machine capacity as such was not investigated at this point. The following was concluded: .The expected head weight, leaf weight, and root weight are 67 per cent, 27 per cent, and 8 per cent, reSpectively, of the total plant weight. More accurate measurements could have been obtained; however, the error resulting from the accuracy of the Spring balances was definitely less than the unavoidable error re- sulting from the soil, dirt, and accumulated water in the leaves of the plant. The error resulting from using the extended thread to estimate the alignment of the plant was less than the error made to determine the part of the root to be contacted or the exact center of the head. It was believed, however, that the harvester will not move in a better straight line than that of the thread, and we are actually interested in the alignment of the plant relative to the machine travel. Since this relative alignment could not be measured, the absolute alignment was measured and used instead Of as an estimate. APPARATUS Description of the Machine The Scott Viner Sugar beet harvester was modified by changing some of the machine elements to harvest cabbage. Some initial elements were removed and new ones were added. The following description gives the features and the func- tion of the basic components labeled in the order by which they handled the plant as shown in the assembly drawing (Appendix III). Lifter Shoes (1) were constructed to align and raise the head from the ground, orient it toward the lifter V- belts, and hold it there until it was gripped and lifted. The Shoes Shown on the drawing are one of the tested de- signs, however, no final decision was made regarding the best design as will be discussed later. A pair of slides were located under the lifter assembly; it carried a portion of the weight of the lifter assembly, the lifted heads and the thrust resulting from the pulling forces. The other portion of the weights and thrust was counterbalanced by a tension Spring. The lifter assembly (carried on the Slides) followed contours Of the ground. In some of the designs the Slides had a plowing action that pushed about three inches Of SOil aside and left the plant on a middle ridge which pro— vided a better approach and grip on the stem for the V—belts. 19 20 The lifter assembly (2) consisted Of two hinged beams that were moved in a vertical plane. Each beam carried free- rotating eight—inch diameter sheave at its lower end which supported the lifter V-belts. The gap between the sheaves could be adjusted by a pair of lifter Shoe Spreaders located under the bottom surface of the hinged beams. Each beam had also a set of four-inch spring—loaded idler pulleys hinged to the inner edge which supported and forced the V-belts against each other. The V-belts were thus able to continuously re- tain a firm grip on the plant from the lifter shoes to the trimming disc knives (4). A pair of adjustable guides (3) was placed just be- fore the disc knives. The overhead belt (5) pressed the cabbage against these guides which changed the grip position on the stem in order to locate the plant at the proper height relative to the disc knives for trimming. The disc knives (4) were mounted on the lifter belt drive shafts, cut the roots and outer leaves from the plant. One of the knives had a plain edge and the other was serrated to insure positive feeding of the stem between them. An overhead belt (5), moving at 1.15 times the Speed of the lifter V-belts, pushed the trimmed heads and the loose leaves over the root deflecting shield (7) to the cleaning belt (8) at the rear of the machine. Its lower end could move up and down and was Spring loaded to control the con- tact pressure between the belt and the cabbage. Two small rollers located at the lower third of the belt made the 21 Space taper from front to rear to accommodate different head sizes. The belt was run at a particular Speed in order to cause the angle of trim to be at right angles to the vertical axis of the head. The root thrower (6) was a 12-inch diameter by 9-inch wide paddle wheel with seven separate compartments, each 3— inches deep. It was placed below the disc knives to catch the cut-off roots and throw them backwards. The wheel was driven with a circumferential Speed 1.5 times the V—belt Speed to produce a centrifugal force great enough to keep the root in contact with the lower surface of the deflecting shield (7). The shield ended at a position where the root could be released to fall to the ground behind the driving mechanism. The trimmed heads and loose leaves fell onto an in— clined cleaning belt (8) which moved slowly upwards. The heads rolled down the incline to the step incline (10) where the elevator (11) carried them to a truck moving along the right side of the machine. The loose leaves were carried up the incline and dropped on the ground. The head deflector (9) oriented the heads to the elevator Side and helped to loosen the cut—off leaves which might still be wrapped around the head. Field Tests After the research work conducted on the machine during the 1961 season, it seemed that this approach to mechanical cabbage harvesting was sound. There were, however, four 22 unsolved problem areas in the machine as follows: 1. Liftin .--The machine did not lift the cabbage satisfactorily. In most cases the lifter shoes and lifter belts pushed the plants ahead, col— lected a large amount of soil, trash, and broke the roots at the throat between the belts. 2. Root removal.--A few approaches had been tried to remove the cut—off roots (at a rate equal to the harvesting rate), but none gave satisfactory results. 3. .Head trimming.--The angle and location of trim- ming were not satisfactorily controlled. Fre- quently the machine discharged a head cut into halves or a head with none of the external leaves removed. The heads were not "square trimmed" in most cases. 4. Loose leaf dropping.--The cleaning belt, having been placed perpendicular to the direction of travel (Figures 1, 3), dropped the loose leaves on the left side of the machine. The leaves fell on an unharvested row that would be sub- sequently harvested. When the author started to work on this project, he was informed about the nature of these problems and was sup- plied with photos showing what had been done. It was quite evident that the lifting problem was the primary problem to be solved; the other three could not be evaluated until a sufficient supply of lifted heads was lifted. The author, therefore, concentrated on lifting until reasonable results were Obtained; then he considered the other problems. The details of the field tests, together with the necessary photos, are given in Appendix II. These tests, however, are summarized in the following tables. TESTS ON LIFTING DEVICES 23 Test Date Fi .No. 1962 Page No Description Results 1 6-11 42 -— Two flat inclined Accumulated soil plates 2 6-12 42 -- Curved inclined Accumulated soil plates 3 6-12 42 -- Small sliding Accumulated soil runners 4 6—13 43 2 Curved small shoes Accumulated soil 5 6-18 43 7 Moldboard plows & Dug into soil gathering bars 6 6-21 43 8 Curved large plates Choked cabbage flow 7 6-25 43 8 Curved large plates Satisfactory, needed manual help 8 6-27 45 -- Two sliding runners Pushed cabbage, no soil problem 9 6-28 45 9 Flat plates and Pushed then lifted runners cabbage 10 6-29 47 9 Same shoes with Pushed then lifted wider gap cabbage 11 7-5 47 -- Similar shoes, but Pushed cabbage and smaller soil 12 7-13 47 -- Strong sliding Pushed cabbage, no runners only soil problem 13 7-31 48 10 Gathering V-belts Pushed cabbage and runners 14 8-2 49 10 Above device with Did not work modifications 15 8-8 49 11 Strong curved Did not work Shields 16 8-9 51 8 Device of test 7 Pushed, then lifted cabbage 24 TESTS ON LIFTING DEVICES (continued) Fig. 19 62 Page No . 'Description Results Test Date NO. 17 8-15 18 9-6 19 9-11 20 9—12 21 9-17 22 -9-21 23 9-25 24 9-26 25 9-27 26 9-28 27 10-2 28 10-5 29 10-9 51 52 52 53 54 55 57 57 58 60 6O 6O 62 12 12 12 12 12 13 14 14 15 16 16 17 18 19 Strong curved shields Above shoes at higher Speed Paddle wheel and above shields Above device at higher paddle Speed Same device at faster travel Speed Stronger paddles, New slides, no slip clutch The same device, wider throat Faster paddle Speed, larger slip force Overhead floating rubber tire Same device with refinements Smaller, rigid, floating paddle— wheel Floating rubber- lined paddle- wheel Same device with plowing slides Pushed and lifted cabbage Pushed cabbage Pushed cabbage, paddle Speed too slow Better results, still pushed cabbage Pushed cabbage Rough Operation, paddles damaged Better performance, still pushed soil Equally well, paddles too fast Pushed cabbage, did not work Did not work Moderate performance Poor performance Better performance 25 TESTS ON LIFTING DEVICES (continued) Fig 19 62 Page No .. Description Results Test Date No. 30 10-11 62 31 10-31 64 20 21 Steel fingers on left sheave Steel fingers on on both sheaves Better performance Excellent perform- ance TESTS ON ROOT REMOVAL, TRIMMING, AND CLEANING DEVICES Fig. 1962 Page No . Description Results Test Date No. 1 9-17 2 9-21 3 9-25 4 9—26 5 10-2 6 10-9 64 66 68 68 7O 70 70 22 23 24 25 26 27 Steep inclined shield below disc knives to drop roots Paddle-wheel below knives and shield Same paddle and a double-deck shield Taper entrance for overhead belt Faster paddle- wheel Slower overhead, Spring-suSpended belt Spring-suSpension modified, trimming efficiency esti- mated. Did not work & was clogged Partially successful, needed modifications Paddle-wheel very successful Trimming poor Effective root re- moval, angled trim- ming & bruising of cabbage Less bruising and inclined trimming Less bruising, better trimming, efficiency 96% 26 TESTS ON ROOT REMOVAL, TRIMMING (continued) W Test Date Fig. No. 1962 Page No. Description Results 7 10—24 72 28 Cleaning belt added Cleaning belt clog- (new lifting ged, satisfactory positive feed) trimming due to better picking 8 10-31 73 -- Faster cleaning Better cleaning, belt satisfactory trim- ming and root re- moval Because of the action of the plowing runners, a force analysis was conducted to study the stability Of the lifting shoes. Special care was taken to prevent unstable conditions which would damage the machine. Such a condition results be- cause the greater the plowing resistance, the deeper the plow- ing action which, in turn, creates greater resistance. T 1y - 2v : Pv : 30° _ ,4 x,____; :2 v H T ‘ pR Fig. i. Velocity R diagram. Fig. ii, Forces acting on - lifter assembly. The lifting V-belts run at twice the travelling speed V (Fig.5.). The root diSplacement and the pulling force, therefore, are along the direction P. The action of the pulling force on the shoes has two components, P v and Ph 27 (Fig. ii). The other forces acting on the lifter assembly are: H = horizontal plowing resistance = 2 btp Where: b = width of each furrow t = depth of the furrow p = soil resistance F = Spring force = PC + kt Where: Fo = force when runners are at ground level k Spring constant R = soil reaction HR = soil friction W = weight of the lifter assembly w = weight of lifted heads, equally distributed X & Y = reactions at the hinge A Summation of the moments of the forces around the hinge,to which the relative moment arms are as shown follows: (F + R) x - Pv (1.1x) - (W + w) 0.6x + Ph (0.64x) - (H + pR) 0.7x 0 {a R (l - 0.7p) = 0.6 (W + w) + 0.7H + 1.1 Pv - 0.64 Ph - F ASSUming: p = 0.5 W + w= 400 lb. H = 2btp = 10 pt "U II 0.8 P 64 lbs. Ph = 0.6 P 48 lbs. F = PC + kt = 180 + kt 28 0.65 R 240 + 7 p-t + 70 - 30 — F0 - kt (7 p - k)t + 280 — 180 = (7 p — k)t + 100 '. R = (10 p -l.5k)t + 150. The unstable conditions occur if R increases with the increase in depth which increases the plowing resistance H and, consequently, R. To avoid this 10p - 1.5k should be negative 3. k > 6.5p In average soils, p = 7 -—> 8 psi 3. k a.60 1bs./unit deflection. This average was obtained with proper leverage of the links carrying the lifter assembly. The Sliding runners were also designed to carry up to 500 pounds soil pressure which is greater than the maximum expected value, 150 pounds. Discussion The results of the preliminary tests (tests 1-5) con- ducted On the machine revealed that the major problem was failure of the lifting mechanism to lift cabbage. The im- portance of the problem was not in the value of one lost head of cabbage to every fifty or sixty heads successfully harvested, but rather that the operator of the tractor will not notice that blocking has started until a mass of cabbage, soil, and trash had developed. He has to step the machine, clean it, and start again. The cleaning of the machine takes more time than would be Spent harvesting fifty or sixty heads. Lifting was subdivided into its basic phases. 29 The approach used was to solve each subdivision separately: 1. 2. Contact with the soil cannot be avoided if the machine is required to Operate close to the ground and graSp the Short cabbage stem. A sliding runner was designed to carry a share of the lifter assembly weight, the lifted plant's weight, and the down thrust resulting from the pulling forces. Knowledge of the average values of pull- ing forces and weight of plants reveals the force to be transmitted to the soil and the area of contact. The shape Of the runner, both the sliding and the leading parts, is determined by the performance required, whether sliding on the ground surface or cutting a passageway into the soil. A gathering element was definitely required. It should work to align the Scattered cabbage heads, raiSe them from contact with the ground to give the lifter-belts room for graSping the stem, and to direct the plant, within limits, to the V—belts. The different types of gathering devices were: a. Curved sheet metal shields. b. Straight and curved bars. c. Loop overhanging elements. d. Power-driven belts. e. Steel fingers on sheaves. The first three types could gather cabbage, the fourth one failed. The curved shields, however, accumulated soil and trash, the straight bars caused frequent 3O breakage of stems. The loop type and the steel fingers were the most successful. 3. Since in cabbage harvesting short stems and a comparatively heavy vegetative growth at the top are handled, there is little probability that the stem could be gripped without external help. The gathering device does half of the job; it orients the plant to the throat of the lifter belts. The second half of keeping the plant in place against the pressure of the traveling machine was left to the soil. But the soil resistance is limited, and this explains why cabbage was pushed ahead in an accumulated mound of soil in most of the tests. A positive feeding device is a must for continuous uniform Operation of the machine. The different types tested were: I a. The gathering belts. b. Overhead paddle. c. Overhead tire. d. Steelfingers on Sheaves. The paddle and the fingers were successful because of their positive mechanical action. The fingers, however, had the advantage of eliminating the meshing problem and feeding the stem perpendicular to the lifter belts which resulted in square trimming. The second problem in the machine was how to get rid of the cut-off roots at the same rate they came into the machine. A properly designed paddle wheel and root deflector completely eliminated the problem after a few trials and 31 modifications. The third problem was the proper trimming. ,The force holding the disc knives against each other was increased such that no heads came through partially trimmed. The lo- cation of cut was effectively controlled by the guides placed before the knives and the new design and SUSpension of the overhead belt. The angle of trim was effectively improved to a square trim when the steel fingers were mounted on the sheaves. The lifter belts gripped the stem almost perpendicularly and the proper speed and SUSpension of the overhead belt kept this grip until the cabbage reached the disc knives. The last problem was the dropping of the cut-off leaves On the row which will be subsequently harvested. The design solution as presented in the assembly drawing (Appendix III) appears as a reasonable alternative to the design adopted in tests (6) and (7). It can handle rather uniformly a continuous flow of cabbage and even provide a better removal of leaves as it has a longer length of contact. However, it has the disadvantage of moving the heavy elevator about two feet backwards which affects the maneuverability of the machine. CONCLUSIONS The application of the principles of the Scott Viner beet harvester to cabbage harvesting was a sound approach. After considerable modification, the experimental machine performed satisfactorily. The basic problems of the machine were solved as follows: 1. Continuous uniform lifting of cabbage was se- cured under the test conditions encountered at the end of the harvest season (October 31 and November 7, 1962). The machine successfully handled different varieties of cabbage under different weather conditions. The root removal problem was completely elimin- ated. A square trim was uniformly obtained with a 96 per cent trimming efficiency. The cleaning belt removed the loose leaves from the heads and dropped them behind the machine; however, more adjustments are desirable. It was also Observed that the harvested heads were free from surface dirt. The physical properties of cabbage were measured; the data obtained were comparable to that gathered by previous research workers. 32 RECOMMENDATIONS FOR FUTURE STUDY The Literature Review revealed a lack of information on the mechanical properties of cabbage. A stUdy of the vertical and horizontal pulling forces, the bending strength of the roots, coefficient of friction with different materials, the bruise-producing pressure, and a weight survey for different varieties and their aver- age dimensions would help in the design of a cabbage harvester. New types of picking and lifting devices utilizing different Shapes of steel fingers and new Sliding runners are recommended for additional study. A depth gage wheel may be a good substitute for the sliding runners. The overhead belt should be tested with a concave steel backing to keep the head in the center and help main- tain, with the proper Speed relative to the lifter belts, a square cut at the desirable position. The field capacity of the machine at various Speeds should be investigated. An economic analysis based on actual figures would help to predict its economic feasibility. Evaluation of different cabbage varieties to find the suitable ones for mechanical harvesting, and which can be used for fresh market or sauerkraut production. Trimming may be difficult for both. 33 34 Study of changing the cultural practices to grow cabbage on a central ridge. This change may provide better lift— ing and cleaner handling for the machine. Bulk handling methods of cabbage should be studied to accommodate the introduction of the mechanical harvester. An information exchange with North Carolina State University regarding their approach to mechanical cabbage harvesting is needed to establish a comparative evaluation of the two approaches. The machine should be tested on cabbage treated with gibberillic acid. This acid increased the stem length in previous tests. Probably, plowing can be eliminated and still a good grip on the stem is available. BIBLIOGRAPHY Agricultural Statistics, 1960. USDA. Pincock, M. G. "Costs and Returns in Producing Processing Cabbage," Department of Agricul- tural Economics, Cornell University, 1958. Stout, B. A. Report on Project 651 - Basic Principles of Harvesting. Part III - Cabbage Harvester. For 1961 Agricultural Experiment Station, Michigan State University. Dixon and Massey. Introduction to Statistical Anal sis. New York: McGraw-Hill Book Company, 1957. 35 APPEND IX APPENDIX I TABLE I Alignment of Roots Measured at Michigan State University Horticulture Farm Distance to thread (in.) Head No. Test 1 Test 2 Test 3 Test 4 Test 5 9-27-62 9-27-62 9-28-62 10-7-62 10—7—62 1 17 17 19 20 20 2 18 19 20 19.5 18 3 18 17.5 19 20 21 4 18.5 18 20 20.5 24 5 17.5 17 20 22 21 6 19.5 20 20 19 22 7 19 17 20 19 23 8 19 19.5 20 20 23 9 19.5 17 21 18 22 10 l9 17 22 19 21 11 19.5 17.5 20 19 22 12 20 15 20.5 19 24 13 19.5 16 20.5 22 24 14 20 19 21 18.5 23 15 18.5 20 20 22 23 16 16.5 15 20.5 19 22 l7 l9 18 20.5 19 22 18 19 15 21 19.5 22.5 l9 l9 17 21 19 22 20 20 21 20 19 24 21 21.5 20 20 21 22 22 20 18 20 18 24 23 l9 19 20 19 22 24 19 18 20 20 23 25 19.5 19 20 21 21 26 19 18 20 18.5 23 27 17.5 17 20 21 20 28 18 16 ' 20 19 23 29 18 19 18 20 —- 30 19 16 -- 19 20 31 18 19 -- 18.5 -- 32 18 20 -- -- 19 33 18 20 -— -- 19 34 16.5 22 -- —- 20 35 17.5 20 -- -- 20 37 38 TABLE II Alignment of Cabbage Heads Measured at Michigan State University HOrticulture Farm Distance to thread (in.) Head No. Test 1 Test 2 Test 3 Test 4 Test 5 9-27-62 9-27-62 9-28—62 10-7-62 10-7-62 1 17 22 18 22 19 2 l8 l7 18 22 17 3 l9 l7 17 24 20 4 18 15 17 24 25 5 17.5 l6 14 25 20 6 19 19 14 22 21 7 l9 17 17 22 23 8 19 20 16 24 25 9 17 18 20 21 18 10 17 20 21 21 16 11 19 14 15 21 22 12 19 18 16 22 25 13 20 17 16 25 26 14 l9 l6 18 21 22 15 18 20 14 26 22 16 15 24 17 21 22 17 18 15 17 20 22 l8 19 17 19 22 21 19 18 15 19 22 21 20 19.5 l8 18 22 22 21 22 24 20 24 20 22 20 20 l7 19 24 23 17 21 21 21 19 24 l9 l9 19 22 21 25 19 20 18 22 19 26 19 20 19 19 22 27 17.5 15 16 27 17 28 18 18 20 21 24 29 18 20 17 22 -- 30 l9 l7 -- 19 19 31 18 20 -— 22 -- 32 18 20 -- -- 15 33 18 20 -— -- 18 34 16 23 —- -- 18 35 17.5 20 -- -- 18 39 TABLE III Physical Measurements Made on Cabbage at Michigan State University Horticulture Farm on 10-7-62 Head Stem Length (in) Test72 Root Dia. ITEst 1 Head Size (in) No. (in) Test’l *fiTest 2 Test 2' Test 1 5 5 0277000) 12345 55 5 90/0/70; 5 5 5 700899 67890 1 2 7L5<5 23221 61795 23223 027992 00001.. 000009 10110 555 76797 555 00902017 26 27 28 29 30 124 333 2.8 677 000 0.9 525:5 77:7. 8.5 31 32 33 TABLE IVa Physical Measurements Made on Cabbage at Michigan State Un ty Horticulture Farm on 1versi 10-7-62 Leaves Wt. Root ’Wt. Wt. Wt. NetHHead Wt. Wt. AALA-_A_ gk ing__orce (lb) u Gross L‘A‘_k~._k Head No. (lb) (in) (lb) % (lb) % (lb) % Wt. Horz. Vert. 4O [\P'JNNv-i MVOO‘OOOOOOH V000”) [\mmmm Nfi'u—I HRH NNNMM MMNNNNNNMN NNNN NNNMNC’) NNM NMM NWOOMWMVWO‘VVVHH[\HO‘MMWKDNMOO‘O‘HNNH NHHNMNMNNHNNNMVHMHNNNHVNMHNMNMM IONOl\l\l\v-l[\O‘MNNFMWOO‘WONO‘MO‘BVOOOO‘FO H 11) 10 In") FWOKOOOWOKOKOOOOOOO‘OOO‘N[\[\[\[\OO[\\OO‘HCX)0‘0“) 100‘[\v-‘lr-IOO[\NV'U’NNFWO‘NO‘OOONWOOKJBNB HOlfiv-i \O\O\O\O\O\O\O\O\O[\\O\O\OV)00000000100100 \ONWO WWWWMWO‘OOOOOO‘OHOOOWHNWMHOFWHHFO \OQ’VIOOVWOWNOOOVO‘WO‘WWQOWQOV‘ONQNVQ If) V) V) V) 10'!) V) 1f) If) town/unto V) OFNWO‘NOOCX)O‘ONO‘NFO‘CDHO‘NO‘O‘O‘O‘GOFCDO‘O‘O‘NOO H WNOV'DCX)OBWOOONNWONOOHWHMHHWWONWO‘ OOOO‘OFO‘O‘OOO‘O‘O‘O‘OOMbmwwO‘O‘wHO‘wOOv-IOOCXDO H H F! 1H rdrifl llnlwlOIVfIOIWINIOINIOINIOININIVI Iq-IconolbIHIOIOINIOIOIOOIOOI—IIOOINI H H v-i OIOINIOIOINIOININIOINIVIOINIOIO [\llfil\0l1\I\Oll\|O‘| IO‘II\I\OIO\I\OIl\I\O|® HmmvaIxooooammvmouoooxoammqlnxolxoooov-I HHHHHHHHHHNNNNNNNNNNMM TABLE IVb 4.» a m5: 0 m > a m z“- 4...: m :2 m H a +4 0 H E 3 o a "-10 440 k 0 O m E >. 4.; -H m H o m u > :3 -H '0 g . If“ F3 4.) I“; La H O 10-7-62 Gross Pulling Force (1b) ‘— Physical Measurements Made on Cabbage at Michigan State Un Head NO. % (1b) % (lb) % (lb) (in) Wt. Horz. Vert. 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