Abstract:
An improved method of harvesting lettuce provide a frame having ground engaging members (eg. wheels, skids, tracks) that enable the frame to move along the rows of lettuce to be harvested. Powered paddles separate each head of lettuce from its stem and root system, thrusting it through the air to a conveyor. A timing arrangement coordinates the paddle actuation with the speed at which each head of lettuce is encountered. As the head is thrust upward, a spray mist emerges from the tip of one paddle and engulfs the cavity that remains after separation from the stem and root. The spray mist can be a liquid and air mixture that contains a desired chemical to prevent discoloration in the area of the “wound” resulting from being torn from the stem and root system.

Description:
This is a divisional application of application Ser. No. 09/635,120, filed Aug. 9, 2000, now U.S. Pat. No. 6,378,281. 
    
    
     CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable 
     REFERENCE TO A “MICROFICHE APPENDIX” 
     Not applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to harvesting machines and methods of harvesting and more particularly, to an improved method and apparatus for harvesting heads of lettuce. Even more particularly, the present invention relates to an improved method and apparatus for harvesting lettuce that features a dual paddle and actuator arrangement that quickly separates a head of lettuce from its root and stem, throwing it to a conveyor. In one embodiment, a sensor or manually operated switch initiates a timing sequence to activate the actuator. A pair of pneumatic cylinders actuate the paddles or flippers that are positioned on opposed sides of a head of lettuce to be picked. The paddles move at a speed that is sufficient to separate the head of lettuce from its stem and root, thrusting it above the underlying earth in an arcuate path to a waiting conveyor. 
     2. General Background of the Invention 
     Typically, the harvesting of lettuce has been a manual operation. However, some patents have issued for machines that purport to be lettuce harvesters. Early examples of lettuce harvester patents include numbers U.S. Pat. Nos. 3,380,234; 3,380,237 and 3,497,013. Another example of an early patent is U.S. Pat. No. 3,731,477 entitled “Harvester for Headed Vegetables”. The &#39;477 patent discloses a high speed lettuce harvesting machine comprising a vehicle adapted to move along vegetable rows to be harvested, a pair of vegetable head-engaging sensing arms mounted on said vehicle, a plurality of sensor belts mounted on said arms, the sensor belts being adapted to be deflected by the circumference of said vegetable head to guide and actuate a cutting blade toward the stem of the vegetable head so as to sever only fully grown heads and to transport them to a conveyor. 
     U.S. Pat. No. 3,632,919 discloses an apparatus to detect mature heads of lettuce in a cropped row. The apparatus includes a mobile support movable along the row, and a support mounted above row vertically floatable detector unit bearing successively on the heads of lettuce as the support moves, the detector unit including a gauge and detector wheel assembly. 
     U.S. Pat. Nos. 3,800,518 and 3,827,503 show tractor mounted lettuce harvesters. 
     An apparatus for removing loose and/or excess leaves from the head of a leafy edible plant is disclosed in U.S. Patent No. 3,821,987 entitled “Lettuce Harvesting Apparatus”. The apparatus includes a conveyor means for conveying the head after the stump has been removed therefrom, with the residual stump portion arranged at the bottom of the head and with the sides of the head unencumbered, whereby the outermost excess leaves fall by gravity from the head during transport from a first position to a second position. In one embodiment, the head is supported solely between the parallel vertically-spaced adjacent runs of upper and lower endless conveyor means, the horizontal run being less than the diameter of the head, whereby the removal of the excess leaves is greatly facilitated with the aid of gravity. The second position may be higher than the first position, in which event the adjacent parallel runs of the upper and lower conveyors are inclined to the horizontal, thereby further assisting in leaf removal. In a second embodiment, the head is supported by generally horizontal conveyor means that include a pair of parallel spaced adjacent longitudinal runs between which are arranged selectively operable cutter means for trimming the residual stump portion of a head and thereby effect removal of excess leaves therefrom. 
     In U.S. Pat. No. 4,094,238, there is provided a lettuce harvester having a positive means for engaging the stems of lettuce to be trimmed whereby the trim cut is caused to take place at right angles to the stem, and the lettuce is left ready for packaging. 
     The Lenker patent U.S. Pat. No. 4,136,509 discloses an apparatus for harvesting vegetable heads. A sensing means including a pair of parallel, laterally movable, head-engaging units, which are counter-rotated, is fixed to a frame. A cutting means is mounted on the frame and is responsive to the sensing means. The cutting means includes a horizontal knife blade rotatable 180 degree for each head cut. The severed head is removed from the cutting area by a pair of counter-rotating lifter belts. 
     The Gray patent U.S. Pat. No. 4,876,844 discloses a field crop harvesting, carton packaging and packed carton handling machine, which includes transport means having a front section, central section and a trailing section. The front and trailing sections include a ground engaging means and each include a platform mounted on the ground engaging means. The front platform also includes an area for stacking and supplying non-erected cartons and for erecting non-erected cartons. The central section includes a conveyor support including a central conveyor means and a left and right conveyor means. The left and right conveyor means each include erected carton receiving and supplying means. The left and right conveyor means include a series of carton packing stations as well as a conveyor for moving the packed cartons to a central conveyor. The control conveyor includes a rearwardly moving conveyor for transporting packed cartons rearwardly to the trailing platform. The trailing platform includes an area for receiving, handling and sealing the packed cartons and distributing the sealed cartons. The apparatus also includes the method of harvesting, carton packaging and packed carton handling together with the steps of cleaning the crop and sealing the same in the cartons. 
     U.S. Pat. No. 5,310,102 is entitled “Apparatus for Field Sleeving of Lettuce and Other Vegetables”. The &#39;102 patent discloses a vegetable sleever suitable for field wrapping of vegetables such as leaf lettuce at the time of harvesting in order to prevent shipping damage. 
     The Ottaway (applicant herein) patent U.S. Pat. No. 5,560,190 is entitled is “Lettuce Harvesting Method and Apparatus to Perform Same”. The &#39;190 patent discloses a method for the automated harvesting of headed row crops, including lettuce, optionally leaving at least the crop root in the ground, and an apparatus to practice the method. The present invention provides a methodology to locate crop stems, separate the outer leaves from the head, grip the stem and harvest the head. Gripping the stem is accomplished with at least one pneumatic gripping bladder. Substantially simultaneous to gripping the head, the head is separated from the core and stem. One method to accomplish this separation is by means of a pair of differential pneumatic bladders which frees the head from the core at the center of the head, leaving the core and the outer leaves attached to the stem and root. Alternatively, a second separation method taught herein is the application of a downward force applied to the top of the head by a pneumatic bladder. The two separation schemes may be used conjointly or in the alternative. As a further alternative, the present invention teaches a harvesting method which cuts the stem at the core, leaving the core within the head and the outer leaves attached to the stem and root. After harvesting, a conveyor means removes the produce to a bin or other receptacle. 
     U.S. Pat. No. 6,050,073 discloses a harvester and method of harvesting leafy vegetables. The disclosed harvester is designed to harvest vegetables which are delicate and are grown in precisely configured beds of either a rectangular or singular width or a double width. A conveyor/cutter assembly is located on one side of the harvester centerline and has a width somewhat exceeding the width of a single width bed. The wheels on each side are separated by somewhat more than the width of a double bed. The driver and engine is located on the other side of the centerline. Such a harvester can cut single width beds, or can cut double width beds by making a first pass in one direction and a second pass in the other direction. An improved single conveyor/cutter assembly is disclosed along with a method of harvesting and processing leafy vegetables to reduce the amount of debris and unwanted material in the harvested leafy vegetables. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides an improved method and apparatus for harvesting lettuce, preferably two or more rows at a time. The lettuce harvester of the present invention includes a frame and a plurality of ground engaging supports. One of the supports is a central support that travels between two rows of lettuce during use. This central ground engaging support is preferably an endless belt-type track. 
     A plurality of paddles are movably supported upon the frame, including preferably a pair of paddles for each row of lettuce to be harvested. The paddles are positioned on opposing sides of a row to be harvested so that two opposed paddles move toward each other and engage the underside of the head of lettuce to be harvested. 
     A powered linkage is provided for moving the paddles between lower and upper positions. As the paddles travel swiftly from the lower to the upper position, they engage and pick a head of lettuce to be harvested. 
     In the preferred embodiment, one of the paddles engages the head of lettuce to be harvested before the other paddle engages the head of lettuce. The time for striking the head of lettuce is delayed slightly for the second paddle, causing the head of lettuce to be separated from its root and stem and to be thrust upwardly and laterally in an arcuate path to a conveyor. The “late hit” by the second paddle imparts a lateral travel component to the head of lettuce, sending it toward the conveyor. 
     An actuator mechanism is provided that moves the paddles at selected time intervals, the actuator operating the powered linkage to move the paddles in a very fast, arcuate path. In the preferred embodiment, the paddles are preferably pivotally attached to the frame. 
     The paddles move at a speed sufficient to thrust each harvested head of lettuce upwardly a distance above the soil of preferably at least 15 inches and preferably between about 15 and 40 inches. 
     The lettuce harvester of the present invention can include a deflector that alters the travel path of any head of lettuce that elevates too far after it is picked by the paddles. The deflector can be in the form of an arcuate cage that extends from a position above the paddles to a position above the conveyor. 
     The apparatus can include a sensor that senses when a head of lettuce is engaged by the machine as it travels forward. The sensor can be a mechanical member carried by the frame that contacts each head of lettuce sequentially as the harvester moves forward. 
     In the preferred embodiment, the sensor engages each head of lettuce and is deflected away by the head of lettuce. This deflection of the sensor activates a switch that initiates a timing sequence. In this fashion, the sensor determines when the paddles are to be operated in order to harvest each sequentially encountered the next head of lettuce. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein: 
     FIG. 1 is a side elevation view of the preferred embodiment of the apparatus of the present invention shown in the harvesting position; 
     FIG. 2 is a sectional view taken along lines  2 — 2  of FIG. 1; 
     FIG. 3 is a sectional view taken along lines  3 — 3  of FIG. 1; 
     FIG. 4 is a sectional view taken along lines  4 — 4  of FIG. 1; 
     FIG. 5 is a schematic end view illustrating the preferred embodiment of the apparatus of the present invention in both two-row and three-row configurations; 
     FIG. 6 is a schematic, fragmentary view illustrating part of the method of the present invention; 
     FIG. 7 is a fragmentary, perspective view of the apparatus of the present invention, and illustrating part of the method of the present invention; 
     FIG. 8 is a schematic diagram of the preferred embodiment of the apparatus of the present invention; 
     FIG. 9 is an elevation view of the preferred embodiment of the apparatus of the present invention showing the harvester in an elevated, non-harvesting transport position; 
     FIG. 10 is an elevation view of the preferred embodiment of the apparatus of the present invention showing an alternate configuration for the harvester ground engaging supports that travel in opposing furrows on sides of the rows of lettuce to be harvested; 
     FIG. 11 is a perspective, fragmentary view of the preferred embodiment of the apparatus of the present invention illustrating the sensor; 
     FIG. 12 is a fragmentary, perspective view illustrating an alternate construction for the sensor; and 
     FIG. 13 is a fragmentary, perspective view of the preferred embodiment of the apparatus of the present invention illustrating the paddle and its mister arrangement for thrusting a spray mist at each head of lettuce as it is picked. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1-4 show generally the preferred embodiment of the apparatus of the present invention, designated generally by the numeral  10 . In FIG. 8, a schematic diagram of the apparatus of the present invention is shown, designated generally by the numeral  10 . 
     Lettuce harvester  10  includes a frame  11  that can move along rows to be harvested. Frame  11  can be self propelled or it can be pulled by a powered mechanical device such as a tractor  20 . 
     The tractor  20  typically provides a hitch  21  such as a commercially available three-point hitch that attaches to frame  11  as shown in FIGS. 1,  4  and  9 . 
     Frame  11  has an upper end portion  12  and a lower end portion  13 . The frame  11  is supported by a plurality of ground engaging supports such as wheels  14 ,  15 , skids  16 ,  17  and central track  22 . The wheels  14 ,  15  include a right wheel  14  that is mounted to frame  11  in front of right skid  16 . Similarly, left wheel  15  is mounted to frame  11  in front of left skid  17 . 
     As shown in FIG. 4, the harvester  10  of the present invention is used to harvest a pair of rows of lettuce designated generally by the numerals  18 ,  19  in FIG. 4, each of the rows  18 ,  19  having a respective plurality of heads of lettuce  30 ,  31  to be harvested. However, more than two rows can be harvested (see FIG.  5 ). In FIG. 5, a schematic illustration shows that the preferred embodiment of the apparatus of the present invention can be used to harvest either two or three rows at a time. The left hand portion of FIG. 5 illustrates schematically the harvesting of two rows  18 ,  19  wherein frame  11  is provided with a single track  22 . The right hand side of FIG. 5 shows a frame  11 A that has two tracks,  22 A,  22 B, for harvesting three rows  75 ,  76 ,  77  of lettuce. The third row of lettuce  77  includes a plurality of heads of lettuce to be harvested, each designated by the numeral  78 . 
     The right wheel  14  and right skid  16  travel in a furrow  28  as shown in FIG.  4 . The left wheel  15  and left skid  17  travel in a furrow  29  as shown in FIG.  4 . Track  22  is as a central support positioned between rows  18 ,  19  and can be in the form of an endless belt  23  supported by a plurality of support rollers  24  that are mounted on frame  11 . Track  22  is preferably an idler track, but it can be driven. 
     During use, a plurality of heads of lettuce  30 ,  31  are to be harvested from each rows  18 ,  19 . During harvesting, each head of lettuce  30 ,  31  is separated from its root  32  and stem  33  as shown in FIGS. 2-4 and  6 - 7 . Each head of lettuce  30 ,  31  is preferably thrust upwardly and laterally (as shown in FIG. 3) by paddles  39 ,  40  along an arcuate path indicated schematically by arrow  34 . At the end of this travel path  34 , each head of lettuce  30 ,  31  enters a hopper  25  having an open bottom. Under the hopper  25  is provided conveyor  36  having endless belt  37 . The heads of lettuce  30 ,  31  that are harvested fall through hopper to conveyor  36 . At conveyor  36 , lettuce is conveyed to a desired receptacle, trailer, truck, cart, box, or the like. Conveyor  36  can be operated with a hydraulic motor such as the hydraulic motor  69  in FIG.  8 . Hydraulic motor  69  is provided with conventional hydraulic fluid flow lines  70 ,  71  for operating the motor  69 . 
     A deflector  26  can be positioned above each row  18  or  19  of a head of lettuce  30 ,  31  to be harvested. Deflector  26  extends laterally as shown in FIG. 3 to hopper  25 . Deflector  26  can be in the form of a plurality of curved bars  26  as shown in FIGS. 1 and 3. It should be understood that the speed of paddles  39  and  40  which harvest each head of lettuce  30  or  31  can be adjusted by adjusting the speed of operation of cylinders  41 ,  42 . Each head of lettuce  30  or  31  is desirably thrust in an arcuate path  34  that does not cause the harvested head of lettuce  30 ,  31  to actually strike the deflector  26 . However, because of the inconsistency of a product such as a growing head of lettuce, it is possible that a particular head of lettuce  30  or  31  might be thrust slightly higher than the rest of the heads of lettuce  30 ,  31  and strike deflector  26 . 
     The operation of the paddles  39 ,  40  is shown more particularly in FIGS. 2,  3 ,  7  and  8 . In FIG. 7, the paddles  39 ,  40  and pneumatic cylinders  40 ,  41  are shown in a perspective view with frame  11  removed for purposes of clarity. Paddles  39 ,  40  are movably, preferably pivotally attached to frame  11  using, for example, a plurality of padeyes  47  that are connected (for example, welded) to frame  11 . 
     Each pneumatic cylinder  41 ,  42  is mounted to frame  11  using, for example, a plurality of padeyes  45  that are connected (for example, welded) to frame  11 . Each pneumatic cylinder  41 ,  42  has a push rod that is attached to an arm that rotates or pivots a paddle. Pneumatic cylinder  41  has push rod  43  that attaches at pinned connection  51  to arm  49 . Arm  49  attaches at bearing  53  to horizontal rod  48 . Each paddle  39 ,  40  is rotatably (preferably pivotally) connected to frame  11  at padeyes  47  with horizontal rods  48  as shown in FIG.  7 . 
     A similar arrangement is shown for the second pneumatic cylinder  42 . Cylinder  42  has a push rod  44  that is connected at pinned connection  52  to arm  50 . Arm  50  attaches at bearing  54  to horizontal rod  48 . Paddle  40  is attached to horizontal rod  48  as shown in FIG.  7 . Pinned connections  46  can be used to attach the upper end portion of each pneumatic cylinder  41 ,  42  to padeyes  45  as shown in FIG.  7 . 
     The paddle  40  can be provided with a misting device that injects a liquid or liquid/air mixture into the cavity that remains on the head.of lettuce  30  or  31  after it is separated from stem  33 . This liquid or liquid/air mixture can include chlorine, water and/or other chemicals to prevent discoloration in the area of the “wound” resulting from being torn from the stem/root system. 
     In FIGS. 7,  8  and  13 , mist  79  is shown being sprayed from outlet  89  at the tip of paddle  40  opposite horizontal rod  48 . The misting device includes a mixed fluid tank  80  that supplies a desired mixture of fluid via flow line  90  to eductor  81 . Eductor  81  mixes liquid from tank  80  with air that is received from control valve  82 . Control valve  82  can be opened or closed to admit a desired volume of air into eductor  81  and thus into flow line  84  that communicates between eductor  81  and swivel coupling  87  (see FIGS.  7  and  13 ). Control line  83  communicates between electrical control panel  64  and control valve  82 . Fluid flow line  84  is shown in FIGS. 7 and 13 communicating with elbow fitting  86  and swivel coupling  87 . A flow channel  88  is formed (eg. milled) within the combination of horizontal rod  48  and paddle  40  as shown in FIG.  13 . Channel  88  communicates with outlet  89  so that when a mixture of air and fluid or fluid only is transmitted to channel  88  via flow line  84 , it is discharged as a mist  79  at outlet  89 . 
     In FIG. 7, arrow  55  schematically indicates the direction of travel of the harvester apparatus  10  during use. As apparatus travels in a forward direction, sensor  38  engages each head of lettuce  30  or  31  to be harvested. Sensor  38  is movably, preferably pivotally attached to frame  11  so that it engages and is deflected away from head of lettuce  38 , as indicated schematically by the arrow  72  in FIG.  8 . 
     When the sensor  38  is deflected in the direction of arrow  72 , it engages and activates sensor switch  63 . Sensor switch  63  is connected via lines  67  and  68  to an electrical control  64 , solenoid valve  60  and computer  62 . Electrical control  64  communicates with computer  62  via line  66 . An electrical power source is provided at electrical power line  65  for powering electrical controls  64 . When sensor switch  63  is activated, a timing sequence is initiated using electrical control  64  and computer  62  to operate solenoid valve  60 . 
     Solenoid valve  60  is supplied with air via flow line  61 . The valve  60  feeds air to each of the pneumatic cylinders  41 ,  42  via air lines  56 - 59  as shown in FIG.  8 . In the preferred embodiment, the paddle  40  begins its rotational path upwardly in the direction of arrows  72  before the paddle  39 . In this fashion, the paddle  40  first strikes the head of lettuce  30  to be harvested as shown in FIG. 3. A short time (eg. 1/1000 seconds) later, the paddle  39  strikes the head of lettuce  30  or  31 . This action causes the head of lettuce  30 ,  31  to travel upwardly and laterally away from the paddles  39 ,  40  as indicated by the travel path arrows  34  in FIG.  3 . 
     In FIG. 9, tractor  20  has elevated its three-point hitch  21  to illustrate the transport position of the harvester  10  prior to and after harvesting operations. 
     In FIG. 10, the wheel  14 ,  15  and skid  16 ,  17  arrangement is replaced with an alternate construction that includes an endless track  74  supported by a plurality of rollers  75 . 
     FIGS. 11 and 12 show different arrangements for the sensor  38 . In FIG. 11, sensor  38  is partially exposed while in FIG. 12 it is almost totally encased within frame  11 . In FIG. 11, sensor  38  has a center arm  91  that is positioned exteriorly of frame  11  in an exposed position. The sensor arm  38  can be belt driven, such as for example driven by one of the rollers  24  that support track  22 . In such an arrangement, belt  92  is driven by roller  24 . The belt  92  is also supported by sheave  93  that drives shaft  94 . FIG. 11, shaft  94  extends externally of frame plate section  11 B and supports sheave  95 . Arm  91  provides a belt  96  that rotates sheave  97  and roller  98 . The roller  98  actually engages a head of lettuce  30  or  31  to be harvested and travels up and over it as indicated schematically by the dotted line  99  in FIG.  11 . 
     In FIG. 12, the only portion of the sensor  38  that extends externally of the plate section  11 A is the roller  98 . Shaft  100  extends through  101  which is an arcuate slot designed to accommodate movement of arm  91  during use. 
     PARTS LIST 
     The following is a list of suitable parts and materials for the various elements of the preferred embodiment of the present invention. 
     
       
         
               
               
             
           
               
                   
               
               
                 PART NO. 
                 DESCRIPTION 
               
               
                   
               
             
             
               
                 10 
                 lettuce harvester 
               
               
                 11 
                 frame 
               
               
                     11A 
                 frame 
               
               
                   11B 
                 frame plate section 
               
               
                 12 
                 upper end portion 
               
               
                 13 
                 lower end portion 
               
               
                 14 
                 right wheel 
               
               
                 15 
                 left wheel 
               
               
                 16 
                 right skid 
               
               
                 17 
                 left skid 
               
               
                 18 
                 lettuce row 
               
               
                 19 
                 lettuce row 
               
               
                 20 
                 tractor 
               
               
                 21 
                 tractor hitch 
               
               
                 22 
                 track 
               
               
                   22B 
                 track 
               
               
                 23 
                 endless belt 
               
               
                 24 
                 support roller 
               
               
                 25 
                 hopper 
               
               
                 26 
                 deflector 
               
               
                 27 
                 earth 
               
               
                 28 
                 furrow 
               
               
                 29 
                 furrow 
               
               
                 30 
                 head of lettuce 
               
               
                 31 
                 head of lettuce 
               
               
                 32 
                 root 
               
               
                 33 
                 stem 
               
               
                 34 
                 arrow 
               
               
                 35 
                 attachment 
               
               
                 36 
                 conveyor 
               
               
                 37 
                 endless belt 
               
               
                 38 
                 sensor 
               
               
                      38A 
                 sensor 
               
               
                 39 
                 paddle 
               
               
                 40 
                 paddle 
               
               
                 41 
                 pneumatic cylinder 
               
               
                 42 
                 pneumatic cylinder 
               
               
                 43 
                 pushrod 
               
               
                 44 
                 pushrod 
               
               
                 45 
                 padeye 
               
               
                 46 
                 pinned connection 
               
               
                 47 
                 padeye 
               
               
                 48 
                 horizontal rod 
               
               
                 49 
                 arm 
               
               
                 50 
                 arm 
               
               
                 51 
                 pinned connection 
               
               
                 52 
                 pinned connection 
               
               
                 53 
                 bearing 
               
               
                 54 
                 bearing 
               
               
                 55 
                 arrow 
               
               
                 56 
                 air line 
               
               
                 57 
                 air line 
               
               
                 58 
                 air line 
               
               
                 59 
                 air line 
               
               
                 60 
                 solenoid valve 
               
               
                 61 
                 supply air 
               
               
                 62 
                 computer 
               
               
                 63 
                 sensor switch 
               
               
                 64 
                 electrical control 
               
               
                 65 
                 electrical power line 
               
               
                 66 
                 line 
               
               
                 67 
                 line 
               
               
                 68 
                 line 
               
               
                 69 
                 hydraulic motor 
               
               
                 70 
                 oil line 
               
               
                 71 
                 oil line 
               
               
                 72 
                 arrow 
               
               
                 73 
                 arrow 
               
               
                 74 
                 endless track 
               
               
                 75 
                 lettuce row 
               
               
                 76 
                 lettuce row 
               
               
                 77 
                 lettuce row 
               
               
                 78 
                 head of lettuce 
               
               
                 79 
                 mist 
               
               
                 80 
                 mixed fluid tank 
               
               
                 81 
                 eductor 
               
               
                 82 
                 air control valve 
               
               
                 83 
                 control line 
               
               
                 84 
                 fluid flow line 
               
               
                 85 
                 arrow 
               
               
                 86 
                 elbow fitting 
               
               
                 87 
                 swivel coupling 
               
               
                 88 
                 channel 
               
               
                 89 
                 outlet 
               
               
                 90 
                 flow line 
               
               
                 91 
                 sensor arm 
               
               
                 92 
                 beet 
               
               
                 93 
                 sheave 
               
               
                 94 
                 shaft 
               
               
                 95 
                 sheave 
               
               
                 96 
                 belt 
               
               
                 97 
                 sheave 
               
               
                 98 
                 roller 
               
               
                 99 
                 dotted line 
               
               
                 100  
                 shaft 
               
               
                 101  
                 slot 
               
               
                   
               
             
          
         
       
     
     The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.