Patent Publication Number: US-2005133619-A1

Title: Rotor type sprinkler with insertable drive subassembly including horisontal turbine and reversing mechanism

Description:
FIELD OF THE INVENTION  
      The present invention relates to irrigation equipment, and more particularly, to sprinklers of the type that use internal turbines to rotate a nozzle to distribute water over turf or other landscaping.  
     BACKGROUND OF THE INVENTION  
      Many regions of the world have inadequate rainfall to support lawns, gardens and other landscaping during dry periods. Sprinklers are commonly used to distribute water over such landscaping in commercial and residential environments. The water is supplied under pressure from municipal sources, wells and storage reservoirs.  
      So called “hose end” sprinklers were at one time in widespread use. As the name implies, they are devices connected to the end of a garden hose for ejecting water in a spray pattern over a lawn or garden. Fixed spray head sprinklers which are connected to an underground network of pipes have come into widespread use for watering smaller areas.  
      Impact drive sprinklers have been used to water landscaping over larger areas starting decades ago. They are mounted to the top of a fixed vertical pipe or riser and have a spring biased arm that oscillates about a vertical axis as a result of one end intercepting a stream of water ejected from a nozzle. The resultant torque causes the nozzle to gradually move over an adjustable arc and a reversing mechanism causes the nozzle to retrace the arc in a repetitive manner.  
      Rotor type sprinklers pioneered by Edwin J. Hunter of Hunter Industries, Inc. have largely supplanted impact drive sprinklers, particularly on golf courses and playing fields. Rotor type sprinklers are quieter, more reliable and distribute a more precise amount of precipitation more uniformly over a more accurately maintained sector size.  
      A rotor type sprinkler typically employs an extensible riser which pops up out of a fixed outer housing when water pressure is applied. The riser has a nozzle in a rotating head mounted at the upper end of the riser. The riser incorporates a turbine which drives the rotating head via a gear train reduction, reversing mechanism and arc adjustment mechanism. The turbine is typically located in the lower part of the riser and rotates about a vertical axis at relatively high spend. Some rotor type sprinklers have an arc return mechanism so that if a vandal twists the riser outside of its arc limits, it will resume oscillation between the arc limits to prevent sidewalks, people and buildings from being watered. Rotor type sprinklers used on golf courses sometimes include an ON/OFF diaphragm valve in the base thereof which is pneumatically or electrically controlled.  
      Rotor type sprinklers include a large number of relatively small parts that must be assembled, either all by hand, or by a combination of hand and automated assembly. Heretofore these parts have been assembled vertically in stages and the assembled parts have been inserted into a riser. It has been tedious and difficult to assemble these rotor type sprinklers and impractical to disassemble them in the factory to fix any failures.  
      One of the primary reasons for failures of rotor type sprinklers in the field is the presence of dirt, grit and other debris which fouls the delicate turbine, gears and seals.  
     SUMMARY OF THE INVENTION  
      It is therefore the primary object of the present invention to provide a rotor type sprinkler with a reduced parts count.  
      It is another object of the present invention to provide a rotor type sprinkler having an improved architecture that makes the assembly thereof quicker and easier.  
      It is still a further object of the present invention to provide a rotor type sprinkler that can be readily disassembled and repaired at the factory to fix any failures.  
      It is another object of the present invention to provide a rotor type sprinkler that has a reduced parts count, is easier to assemble and has an adjustable arc feature desired by most customers.  
      It is still another object of the present invention to reduce the failure rate of rotor type sprinklers in the field due to the presence of dirt, grit and other debris.  
      According to the present invention, a sprinkler includes an outer housing having a lower end connectable to a source of pressurized water and a riser that is vertically reciprocable within the outer housing along a vertical axis between extended and retracted positions when the source of pressurized water is turned ON and OFF. A nozzle is mounted at an upper end of the riser for rotation about a vertical axis. A turbine is mounted inside the riser for rotation about a horizontal axis, as distinguished from the vertical axis. A drive mechanism connects the turbine to the nozzle so that when the source of pressurized water is turned ON the resulting rotation of the turbine by the pressurized water will rotate the nozzle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a side elevation view of a rotor type sprinkler in accordance with the preferred embodiment of the present invention.  
       FIG. 2  is a vertical sectional view of the sprinkler taken along line  2 - 2  of  FIG. 1 .  
       FIG. 3  is a top plan view of the sprinkler taken from the upper end of  FIG. 1 .  
       FIG. 4  is a vertical sectional view of the sprinkler taken along line  4 - 4  of  FIG. 3 .  
       FIG. 5  is a horizontal sectional view of the sprinkler taken along line  5 - 5  of  FIG. 4 .  
       FIG. 6  is a bottom plan view of the sprinkler taken from the lower end of  FIG. 1 .  
       FIG. 7  is a horizontal sectional view of the sprinkler taken along line  7 - 7  of  FIG. 1 .  
       FIG. 8  is a horizontal sectional view of the sprinkler taken along line  8 - 8  of  FIG. 1 .  
       FIG. 9  is a greatly enlarged fragmentary portion of  FIG. 2  showing details of the reversing mechanism of the sprinkler.  
       FIG. 10  is a greatly enlarged fragmentary portion of  FIG. 4  showing further details of the reversing mechanism of the sprinkler.  
       FIG. 11  is a side elevation view of the riser of the sprinkler of  FIG. 1 .  
       FIG. 12A  is a side elevation view of the riser rotated one hundred and eighty degrees relative to  FIG. 11 .  
       FIG. 12B  is a top plan view of the riser of  FIG. 12A .  
       FIG. 13  is a vertical sectional view of the riser taken along line  13 - 13  of  FIG. 12A .  
       FIG. 14  is a vertical sectional view of the riser taken along line  14 - 14  of  FIG. 12A .  
       FIG. 15  is a vertical sectional view of the riser taken along line  15 - 15  of  FIG. 12B .  
       FIG. 16  is a horizontal sectional view of the riser taken along line  16 - 16  of  FIG. 15 .  
       FIG. 17  is a greatly enlarged version of  FIG. 16 .  
       FIG. 18  is a side elevation view of the drive subassembly, shift disk and turret coupling assembly of the sprinkler of  FIG. 1 .  
       FIG. 19  is a top plan view of the turret coupling assembly taken from the upper end of  FIG. 18 .  
       FIG. 20  is a vertical sectional view of the drive subassembly, shift disk and turret coupling assembly taken along line  20 - 20  of  FIG. 19 .  
       FIG. 21  is a vertical sectional view of the drive subassembly, shift disk and turret coupling assembly taken along line  21 - 21  of  FIG. 20 .  
       FIG. 22  is a greatly enlarged fragmentary portion of  FIG. 20  showing further details of the turbine, gear train reduction, reversing clutch and driven bevel gears of the drive subassembly.  
       FIG. 23  is a greatly enlarged fragmentary portion of  FIG. 21  showing further details of the reversing clutch, driven bevel gears and toggle over-center mechanism of the drive subassembly.  
       FIG. 24  is a greatly enlarged fragmentary portion of  FIG. 20  showing further details of the reversing clutch, driven bevel gears and toggle over-center mechanism of the drive subassembly.  
       FIG. 25  is a side elevation view of the drive subassembly, shift disk and turret coupling assembly of the sprinkler of  FIG. 1  taken from the left side of  FIG. 18 .  
       FIG. 26  is a horizontal sectional view taken along line  26 - 26  of  FIG. 25 .  
       FIG. 27  is a bottom plan view of the drive subassembly taken from the lower end of  FIG. 25 .  
       FIG. 28  is a vertical sectional view of the drive subassembly, shift disk and turret coupling assembly taken along line  28 - 28  of  FIG. 25 .  
       FIG. 29  is a vertical sectional view of the drive subassembly, shift disk and turret coupling assembly taken along line  29 - 29  of  FIG. 25 .  
       FIG. 30  is a vertical sectional view of the drive subassembly, shift disk and turret coupling assembly taken along line  30 - 30  of  FIG. 25 .  
       FIG. 31  is a greatly enlarged version of  FIG. 26  illustrating details of the drive subassembly, shift disk and drive basket.  
       FIG. 32  is a greatly enlarged fragmentary portion of  FIG. 28  illustrating further details of the toggle over-center mechanism of the drive subassembly.  
       FIG. 33  is an enlarged, fragmentary perspective view of the upper portion of the drive subassembly and the turret coupling assembly.  
       FIG. 34  is an enlarged, fragmentary perspective view of the upper portion of the drive subassembly and the turret coupling assembly similar to  FIG. 34  but taken from a slightly different angle.  
       FIG. 35  is an enlarged perspective view of the twin lever assembly of the over-center mechanism of the drive subassembly.  
       FIG. 36  is a side elevation view of the twin lever assembly.  
       FIG. 37  is an end elevation view of the twin lever assembly taken from the left side of  FIG. 36 .  
       FIG. 38  is a bottom plan view of the twin lever assembly taken from the lower end of  FIG. 36 .  
       FIG. 39  is a sectional view of the twin lever assembly taken along line  39 - 39  of  FIG. 38 .  
       FIG. 40  is a greatly enlarged side elevation view of the reversing clutch and driven bevel gears of the reversing mechanism of the drive subassembly of  FIGS. 18-34 .  
       FIG. 41  is a front elevation view of the reversing clutch and driven bevel gears taken form the left side of  FIG. 40 .  
       FIG. 42  is a horizontal sectional view of the reversing clutch and driven bevel gears taken along line  42 - 42  of  FIG. 40 .  
       FIG. 43  is a vertical sectional view of the reversing clutch and driven bevel gears taken along line  43 - 43  of  FIG. 41 .  
       FIG. 44  is a cross-sectional view of the reversing clutch and driven bevel gears taken along line  44 - 44  of  FIG. 43 .  
       FIG. 45  is a cross-sectional view of the reversing clutch and driven bevel gears taken along line  45 - 45  of  FIG. 43 .  
       FIG. 46  is a cross-sectional view of the reversing clutch and driven bevel gears taken along line  46 - 46  of  FIG. 43 .  
       FIG. 47  is a diagonal sectional view of the reversing clutch and driven bevel gears taken along line  47 - 47  of  FIG. 43 .  
       FIGS. 48 and 49  are two different perspective views taken from different angles of the reversing clutch and driven bevel gears of the reversing mechanism of the drive subassembly of  FIGS. 18-34 .  
       FIG. 50  is an enlarged, fragmentary perspective view of the lower portion of the drive subassembly illustrating details of its adjustable stator.  
       FIG. 51  is an enlarged perspective view taken from the upper end of the valve member and spring of the adjustable stator.  
       FIG. 52  is an enlarged top plan view of the valve member and spring of the adjustable stator.  
       FIG. 53  is an enlarged perspective view taken from the lower end of the valve member and spring of the adjustable stator.  
       FIG. 54  is an enlarged side elevation view of the valve member of the adjustable stator.  
       FIG. 55  is an enlarged side elevation view of the valve member and spring of the adjustable stator rotated ninety degrees from its position illustrated in  FIG. 54 .  
       FIG. 56  is an enlarged vertical sectional view of the valve member and spring of the adjustable stator taken along line  56 - 56  of  FIG. 55 .  
       FIG. 57  is an enlarged bottom plan view of the valve member of the adjustable stator taken from the lower end of  FIG. 55 .  
       FIG. 58  is top plan view of the turret coupling assembly of the sprinkler of  FIGS. 1, 2  and  4  taken from the top of  FIG. 62 .  
       FIG. 59  is a vertical sectional view of the turret coupling assembly taken along line  59 - 59  of  FIG. 58 .  
       FIG. 60  is a horizontal sectional view taken along line  60 - 60  of  FIG. 70  illustrating further details of the turret coupling assembly and illustrating the shift disk that cooperates with the turret coupling assembly.  
       FIG. 61  is an inverted vertical sectional view through the turret coupling assembly and shift disk taken along line  61 - 61  of  FIG. 60 .  
       FIG. 62  is a side elevation view of the turret coupling assembly and shift disk.  
       FIG. 63  is a vertical sectional view of the turret coupling assembly taken along line  63 - 63  of  FIG. 62 .  
       FIG. 64  is a vertical sectional view of the turret coupling assembly and shift disk taken along line  64 - 64  of  FIG. 58 .  
       FIG. 65  is a horizontal sectional view taken along line  65 - 65  of  FIG. 59  illustrating details of the conical drive basket of the turret coupling assembly and the shift disk.  
       FIG. 66  is a horizontal sectional view taken along line  66 - 66  of  FIG. 59  illustrating further details of the turret coupling assembly and shift disk.  
       FIG. 67  is a perspective view of one side of the turret coupling assembly and shift disk.  
       FIG. 68  is a perspective view of the other side of the turret coupling assembly and shift disk.  
       FIG. 69  is a vertical sectional view of the drive subassembly, turret coupling assembly and shift disk of the sprinkler of  FIGS. 1, 2  and  4  taken along line  69 - 69  of  FIG. 70 .  
       FIG. 70  is a side elevation view of the drive subassembly, turret coupling assembly and shift disk of the sprinkler of  FIGS. 1, 2  and  4 .  
       FIG. 71  is a vertical sectional view of the drive subassembly, turret coupling assembly and shift disk of the sprinkler of  FIGS. 1, 2  and  4  taken along line  71 - 71  of  FIG. 70 .  
       FIG. 72  is a vertical sectional view of the drive subassembly, turret coupling assembly and shift disk of the sprinkler of  FIGS. 1, 2  and  4  taken along line  72 - 72  of  FIG. 70 .  
       FIG. 73  is a horizontal sectional view taken along lines  73 - 73  of  FIG. 69  illustrating further details of the drive subassembly, turret coupling assembly, conical drive basket, over-center mechanism and shift disk.  
       FIG. 74  is a horizontal sectional view taken along lines  74 - 74  of  FIG. 70  illustrating further details of the turret coupling assembly, conical drive basket, drive subassembly case members, over-center mechanism and shift disk.  
       FIG. 75  is a side elevation view of the drive subassembly, turret coupling assembly and shift disk of the sprinkler of  FIGS. 1, 2  and  4  rotated ninety degrees about a vertical axis from the side elevation view illustrated in  FIG. 70 .  
       FIG. 76  is a top plan elevation view taken from the top of  FIG. 72  illustrating further details of the turret coupling assembly.  
       FIG. 77  is a horizontal sectional view taken along line  77 - 77  of  FIG. 79  illustrating further details of the bevel gear reversing mechanism.  
       FIG. 78  is a vertical sectional view taken along line  78 - 78  of  FIG. 76 .  
       FIG. 79  is a vertical sectional view taken along line  79 - 79  of  FIG. 78  illustrating further details of the drive subassembly, bevel gear reversing mechanism, over-center mechanism, shift disk and turret coupling assembly.  
       FIGS. 80 and 81  are vertical sectional views of the sprinkler of  FIG. 1  similar to  FIGS. 2 and 4 , respectively, illustrating the riser in its extended and retracted positions.  
       FIG. 82  is a fragmentary vertical sectional view of the lower end of an alternate embodiment of the sprinkler of the present invention taken along line  82 - 82  of  FIG. 90  illustrating its bi-level strainer and scrubber.  
       FIG. 83  is a horizontal cross-sectional view taken along line  83 - 83  of  FIG. 82 .  
       FIG. 84  is a side elevation view of the lower end of the alternate sprinkler embodiment illustrated in  FIG. 82 .  
       FIG. 85  is a cross-sectional view taken along line  85 - 85  of  FIG. 84 .  
       FIG. 86  is a vertical sectional view of the alternate embodiment of the sprinkler taken along line  86 - 86  of  FIG. 89 .  
       FIG. 87  is a horizontal sectional view of the lower end of the alternate embodiment taken along line  87 - 87  of  FIG. 86 .  
       FIG. 88  is a horizontal sectional view of the alternate embodiment taken along line  88 - 88  of  FIG. 90 .  
       FIG. 89  is a top plan view of the alternate embodiment.  
       FIG. 90  is a side elevation view of the upper end of the alternate embodiment.  
       FIG. 91  is a fragmentary side elevation view of the lower end of the riser of the alternate embodiment of the sprinkler showing its ribbed inner cylindrical housing.  
       FIG. 92  is a fragmentary side elevation view of the lower end of the riser of the alternate embodiment of the sprinkler showing its ribbed inner cylindrical housing and rotated ninety degrees about a vertical axis from the view of  FIG. 91 .  
       FIG. 93  is a vertical sectional view taken along line  93 - 93  of  FIG. 92 .  
       FIG. 94  is a vertical sectional view taken along line  94 - 94  of  FIG. 92 .  
       FIG. 95  is a vertical sectional view taken along line  95 - 95  of  FIG. 93 .  
       FIG. 96  is a bottom plan view of the riser of the alternate embodiment of the sprinkler taken from the lower end of  FIG. 92 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
      In accordance with the present invention, a pop-up rotor type sprinkler  10  ( FIG. 1 ) includes an outer cylindrical housing  12  having a lower end connectable to a source of pressurized water (not illustrated) and an inner cylindrical riser  14  ( FIGS. 11-15 ) that is vertically reciprocable along a vertical axis within the outer housing  12  between extended and retracted positions when the source of pressurized water is turned ON and OFF. The retracted or lowered position of the riser  14  is illustrated in  FIGS. 2 and 4 . The extended or raised position of the riser  14  is illustrated in  FIGS. 80 and 81 . The sprinkler  10  is normally buried in the ground with its upper end level with the surface of the soil. The riser  14  pops up to spray water on the surrounding landscaping in response to commands from an electronic irrigation controller that turn a solenoid actuated water supply valve ON in accordance with a water program previously entered by a homeowner or by maintenance personnel. When the irrigation controller turns the solenoid OFF, the flow of pressurized water to the sprinkler  10  is terminated and the riser retracts so that it will not be unsightly and will not be an obstacle to persons walking or playing at the location of the sprinkler  10 , or to a mower.  
      The riser  14  ( FIGS. 2 and 3 ) is biased to its retracted position by a large coil spring  15  that surrounds the riser  14 . The lower end of the coil spring  15  is retained by a flange  14   a  ( FIG. 4 ) formed on the lower end of the riser  14 . The upper end of the coil spring  15  is retained by a female threaded cap  16  that screws over a male threaded exterior segment  12   a  ( FIG. 4 ) at the upper end of the outer housing  12 . A nozzle  17  is mounted in a rotatable head or turret  18  ( FIGS. 11-15 ) at an upper end of the riser  14  for rotation about a vertical axis.  
      A turbine  20  ( FIGS. 4 and 22 ) is mounted inside the riser  14  for rotation about a horizontal axis, as distinguished from the vertical axis. A drive mechanism hereafter described in detail connects the turbine  20  to the turret  18  containing the nozzle  17  so that when the source of pressurized water is turned ON the resulting rotation of the turbine  20  by the pressurized water will rotate the nozzle  17  about the vertical axis. The turbine  20  drives a gear train reduction  24  ( FIG. 15 ) that in turn drives a reversing mechanism  26  ( FIG. 9 ). Except for the various springs and axles and the elastomeric components specifically identified, the components of the sprinkler  10  are made of injection molded thermoplastic material.  
      The outer housing  12 , the inner housing  14 , and the cap  16  are preferably molded of UV resistant black colored ABS plastic. A cap member  27  ( FIGS. 2-4  and  13 ) covers the upper end of the turret  18 . The cap member  27  is molded of a UV resistant black colored elastomeric material and has three cross-hair slits  27   a ,  27   b  and  27   c  ( FIG. 3 ) through which the shaft of a conventional HUNTERS® hand tool may be inserted to raise and lower a flow stream interrupter, adjust one of the arc limits or actuate a flow stop valve.  
      The turbine  20 , gear train reduction  24  and reversing mechanism  26  are assembled inside one of two case members  28  and  30  to form a self-contained drive subassembly  32  ( FIGS. 25-30 ). The case members  28  and  30  extend vertically and form opposite halves of a hollow container. The case members  28  and  30  are joined together along planar abutting peripheral flanges such as  28   a  and  30   a  visible in  FIG. 18  before being inserted into the cylindrical inner housing  34  that forms the exterior of the riser  14 . The case members  28  and  30  may be joined by sonic welding, adhesive, or other suitable means once the drive mechanisms mounted therein have been tested and found to be fully operative.  
      The importance of the architecture of the drive subassembly  32  will not be lost on those familiar with the manufacture of rotor type sprinklers. The turbine  20 , as well as the axles and the tiny spur and pinion gears of the gear train reduction  24  and the reversing mechanism  26 , and their related linkages, can be automatically or manually laid in place inside corresponding slots and depressions molded into the case member  28  when laid flat with its open side facing upwardly. The other case member  30  can then be snapped in place, with the aid of mating projections and detents, over the case member  28 . The drive mechanisms inside the drive subassembly  32  can then be tested on the assembly line and the case members  28  and  30  can be snapped apart to replace any defective components or fix any jams. Once the drive mechanisms have been tested and shown to be functional on the assembly line, the case members  28  and  30  can be permanently joined in claim shell arrangement and slid into the inner cylindrical housing  34  of the riser  14 . This is a greatly advantageous arrangement to that employed in conventional rotor type sprinklers in which a free-standing vertical stack of tiny gears and other drive components must be assembled in tedious fashion and inserted into the riser, from which they cannot be easily removed for repair. Also, as will be apparent from the drawings and accompanying description, the parts count in the sprinkler  10  is significantly less than that of conventional arc adjustable rotor type sprinklers.  
      The turbine  20  ( FIGS. 4, 15 ,  20  and  22 ) is a Pelton type turbine that includes a central cylindrical hollow shaft  36  ( FIG. 22 ), a disc  38  and a plurality of equally circumferentially spaced cups or buckets  40  formed on the periphery of the disc  38 . The buckets  40  each have an identical wedge shape that includes a beveled or sharp leading edge and a hollow, rearwardly facing opening against which a stream of water is directed. The turbine  20  is mounted for high speed rotation within mating annular housing portions  42  and  44  ( FIG. 18 ) of the case members  28  and  30 , respectively. The cylindrical hollow shaft  36  of the turbine  20  is mounted in a bearing  46  ( FIG. 22 ). A pinion gear  48  formed on one end of the shaft  36  engages and drives a spur gear  50  forming part of the gear train reduction  24 . The bearing  46  also functions as a seal to prevent a continuous flow of water from the turbine housing formed by the housing portions  42  and  44  into the hollow portions between the case members  28  and  30  that enclose the gear train reduction  24  and the bevel gear reversing mechanism  26 . These areas fill up with water since the case members  28  and  30  are not hermetically sealed together. However, there is no continuous flow of water through the areas of the drive subassembly  32  containing the gear train reduction  24  and the reversing mechanism  26  that could carry grit to these sensitive mechanisms and cause them to fail.  
      A vertically elongated rectangular hollow chute  52  ( FIG. 18 ) provides a water flow path to a pair of inlet holes  53  ( FIG. 7 ) to the housing portion  42  for directing a stream of water against the hollow rearward facing sides of the buckets  40  of the Pelton turbine  20 . The chute  52  extends tangentially to the outer circumference of the turbine  20  for maximum efficiency in directing the stream of water that flows through same to impart rotation to the turbine  20 . Pressurized water enters the cylindrical outer housing  12  through its female threaded lower inlet  12   b  ( FIG. 4 ) and passes through a frusto-conical screen or strainer  54 . A first portion of this water then passes a finer mesh section  54   a  of the strainer  54  and then through the chute  52  ( FIG. 18 ) and the inlet holes  53  ( FIG. 7 ) and drives the turbine  20 .  
      A second portion of the water flows through a coarser mesh section  54   b  of the strainer  54  and then vertically through the space  56  ( FIG. 14 ) between the exterior of the drive subassembly  32  and the cylindrical inner housing  34  of the riser  14  and out the nozzle  17 . The first portion of water that drives the turbine  20  passes out of the drive subassembly  32  through a round outlet aperture  58  ( FIG. 18 ) in a lower part of the periphery of the annular housing portion  44 . The outlet aperture  58  is illustrated in phantom lines in  FIG. 18 . The first portion of the water exiting the outlet aperture  58  joins the upwardly flowing second portion flowing through the space  56  ( FIG. 14 ) and ultimately exits the riser  14  via the nozzle  17  along with the second portion of the water. Less than five percent of the water flowing through the sprinkler  10  actually drives the turbine  20 . The remainder flows directly to the nozzle  17  via the space  56  between the drive subassembly  32  and the inner housing  34 . Since the bulk of the water never reaches or comes into contact with the sensitive mechanisms inside the drive subassembly  32  it need only be coarsely filtered, and the reach of the stream of water ejected from the nozzle  17  is maximized.  
      My sprinkler  10  advantageously divides the water that flows into the riser  14  into two different portions and subjects them to different levels of filtering. A first portion that enters the drive subassembly  32  must pass through a finer mesh section  54   a  ( FIG. 2 ) of the strainer  54  than the second portion. The second portion of the water only flows around the drive subassembly  32  and therefore only passes through a coarser mesh section  54   b  of the strainer  54 . The mesh sections  54   a  and  54   b  represent separate filters for different portions of the water inflow. The water that comes into contact with the delicate turbine  20  is subject to more intensive filtering than the water that only flows around the drive assembly  32 . However, it is still necessary to subject the water that bypasses the turbine  20  to some degree of filtering to prevent the smallest orifice in the nozzle  17  from becoming clogged.  
      The self-contained clam shell drive subassembly  32  of my sprinkler  10  is advantageously suited for assembly line production. The Pelton turbine  20 , the various gears of the gear train reduction  24 , the parts of the reversing mechanism  26 , as well as various additional mechanisms hereafter described can be manually or automatically laid into the corresponding recesses and compartments formed in a first one of the two case members  28  and  30  when it is laid horizontal. The second case member can then be snapped into place over the first case member. The completed drive subassembly  32  can then be inserted into the inner cylindrical housing  34  of the riser  14 .  
      On occasion it would be desirable for the sprinkler  10  to rotate its nozzle  17  much more rapidly than during normal irrigation. For example, a higher than normal nozzle rotation speed may be desirable for dust control, washing of chemicals from turf and plants, and the protection of vegetation from near freezing or freezing conditions. A quick application of water via high speed rotation of the nozzle  17  is an acceptable way to accomplish these beneficial results. The sprinkler  10  incorporates a manually adjustable stator  60  ( FIGS. 50-57 ) that is mounted within the riser  14  directly beneath the drive subassembly  32  for varying a nominal rotational speed of the turbine  20  for an expected water pressure. The stator  60  includes a vertical central box-like frame portion  62  that encloses a coil spring  64 . The lower end of the spring  64  surrounds a cylindrical mandrel  66  ( FIG. 56 ) seated on the bottom wall of the frame portion  62 . Spaced apart flat valve members  68  and  70  ( FIGS. 51 and 57 ) extend horizontally from the upper end of the frame portion  62  and are reinforced by triangular ribs  72  and  74  ( FIG. 55 ), respectively. The spring biased valve members  68  and  70  of the adjustable stator  60  slide up and down relative the lower end plate  76  ( FIGS. 14 and 18 ) of the drive subassembly  32  in a manner that has the effect of changing the pressure of the first portion of the water that drives the turbine  20 . This results in a change in the speed of rotation of the turbine  20 .  
      The location of the adjustable stator  60  within the drive subassembly  32  is illustrated in  FIGS. 15 and 20 . The upper end of the coil spring  64  presses against the disc-shaped housing portion  78  of the drive subassembly  32  that encloses the spur gear  50  of the gear train reduction  24 . The horizontal valve members  68  and  70 , and their supporting ribs  72  and  74  slide up and down relative to the end plate  76  on either side of the disc-shaped housing portion  78 . The end plate  76  is formed with a pair of apertures  80  and  82  ( FIG. 27 ) that are complementary in shape, and aligned with, the valve members  68  and  70 .  
      The vertical position of the cylindrical mandrel  66  is adjustable by placing the tip of a screwdriver or other tool (not illustrated) in a diametric slot  84  ( FIG. 57 ) formed in the lower end of the mandrel  66 . The screwdriver can be inserted through a round hole  85  formed in the bottom wall  62   a  ( FIG. 53 ) of frame portion  62  of the adjustable stator  60 . The screwdriver is twisted to unlock mating detents and projections (not illustrated) formed on the mandrel  66  and the lower end of the frame portion  62 . This allows the mandrel  66  to be moved to one of a plurality of predetermined vertical positions within the frame portion  62  where it can be twisted again and locked into a new position. This adjusts the downward biasing force exerted by the coil spring  64  against the adjustable stator  60 . This changes the pressure of the first portion of the water entering the threaded lower inlet  12   b  that drives the turbine  20 , thereby varying the speed of rotation of the turbine  20 .  
      Details of the reversing mechanism  26  ( FIG. 9 ) will now be discussed. It includes upper and lower parallel bevel gears  86  and  88  ( FIGS. 24, 29 ,  33 ,  34 , and  40 - 49 ) that are simultaneously driven in opposite directions by a central bevel pinion gear  90  (FIGS.  40 ,  42 - 44 ). The bevel pinion gear  90  is indirectly driven by the turbine  20  through the gear train reduction  24  that includes spur gear  92 . A reciprocating cylindrical clutch  94  ( FIGS. 23, 24 ,  34 ,  40 ,  41  and  43 ) slides up and down around a central vertical drive shaft  95  ( FIGS. 24, 33  and  34 ). The clutch  94  has radially extending teeth  96  ( FIG. 23 ) and  98  ( FIG. 40 ) formed on the upper and lower sides thereof. The teeth  96  and  98  selectively engage with radially extending teeth  100  and  102  ( FIG. 43 ), respectively, formed on the lower and upper sides of the bevel gears  86  and  88 . This provides a positive driving engagement between the clutch  94  and either of the bevel gears  86  and  88 .  
      The clutch  94  is moved up and down by a vertically reciprocable horizontally extending yoke  104  ( FIGS. 9 and 23 ) that partially encircles a smooth central cylindrical portion of the clutch  94 . The yoke  104  engages upper and lower shoulders  94   a  and  94   b  ( FIG. 9 ) of the cylindrical clutch  94  to drive the same up and down. This selectively engages the upper teeth  96  or the lower teeth  98  of the clutch  94  either with the teeth  100  of the upper bevel gear  86  or the teeth  102  of lower bevel gear  88 . The clutch  94  is vertically reciprocable, but splined to, the vertical drive shaft  95 . The upper end of the drive shaft  95  is rigidly secured to the lower end of an inverted conical drive basket  106  ( FIG. 13 ). The drive basket  106  rotates the turret  18  containing the nozzle  17  clockwise and counter-clockwise through a turret coupling assembly  124  described hereafter in detail. The drive basket  106  includes four circumferentially spaced, upwardly diverging arms  106   a  ( FIG. 21 ) between which the water flows in order to reach the nozzle  17 . The bevel gears  86  and  88  ( FIG. 40 ) are both continuously and simultaneously rotated in opposite directions by the bevel pinon gear  90  as long as the turbine  20  rotates. The clutch  94  is moved up and down to selectively couple either the upper bevel gear  86  or the lower bevel gear  88  to the vertical drive shaft  95 . The drive shaft  95  rotates freely in the opposite direction of the particular one of the bevel gears  86  and  88  to which it is not coupled.  
      Gear driven rotor type sprinklers need to have a mechanism for shifting the reversing mechanism thereof. My sprinkler  10  incorporates a unique toggle over-center mechanism  108  ( FIGS. 10, 23 , and  32 - 39 ) which shifts the reversing mechanism  26 . The toggle over-center mechanism has a only single spring  118  and has no “dead spot.” . The drive subassembly  32  includes, as part of the reversing mechanism  26 , the toggle over-center mechanism  108 . The toggle over-center mechanism  108  moves a link arm  110  ( FIGS. 23, 32  and  34 ) up and down. The yoke  104  is connected to the lower end of the link arm  110 . The link arm  110  slides within a conformably shaped guide portion  112  ( FIG. 18 ) of the case member  28  which serves to retain the link arm  110  in position. The link arm  110  has a pair of upper and lower shoulders  110   a  and  110   b  ( FIG. 23 ) that are engaged by the rounded outer end of a first lever  114  ( FIG. 36 ) to move the link arm  110  between raised and lowered positions that selectively couple the clutch  94  to the upper bevel gear  86  and the lower bevel gear  88 , respectively.  
      The over-center mechanism  108  further includes a second lever  116  ( FIG. 36 ). The two levers  114  and  116  are held against each other by the spring  118  ( FIG. 39 ) which functions as an expansion spring. The first lever  114  is formed with a pair of trunnions  120  ( FIGS. 35, 36  and  38 ) that act as a fixed center bearing point. The second lever  116  does not have a fixed center point but is instead formed with a pair of C-shaped recesses or bearing surfaces  123  ( FIG. 39 ) that have a flat center section and curved end sections. The first lever  114  is formed of parallel, spaced apart, arrow-head shaped, flat side pieces  114   a  and  114   b  ( FIG. 35 ). The second lever  116  is formed of parallel, spaced apart, triangular side pieces  116   a  and  116   b  ( FIG. 35 ). The trunnions  120  ( FIGS. 35, 36  and  38 ) are formed on one set of ends of the side pieces  114   a  and  114   b . The bearing surfaces  122  ( FIG. 39 ) are formed intermediate the lengths of one set of straight edges of the triangular side pieces  116   a  and  116   b . The first and second levers  114  and  116  are mated so that each of the trunnions  120  engages a corresponding one of the bearing surfaces  123  as best seen in  FIGS. 35, 36  and  39 . The spring  118  ( FIG. 39 ) holds the first and second levers  114  and  116  together.  
      A first C-shaped end  118   a  ( FIG. 39 ) of the spring  118  is retained about a post  114   c  formed at one end of the first lever  114 . A second C-shaped end  118   b  ( FIG. 39 ) of the spring  118  is retained about a post  116   c  formed at one end of the first lever  116 . The second lever  116  is formed with an upstanding L-shaped actuating arm  121  ( FIGS. 32 and 35 - 37 ). The actuating arm  121  extends through a slot in formed in the upper ends of the case members  28  and  30  where they mate and is engaged and moved back and forth by the spaced apart legs  122   a  and  122   b  ( FIGS. 31 and 32 ) of a horseshoe-shaped shift disk  122  ( FIGS. 33, 34 ,  60 ,  62 ,  65 ,  66 ,  68 ,  73  and  74 ).  
      The two levers  114  and  116  ( FIG. 36 ) of the over-center mechanism  108  are held against each other by the spring  118 . The trunnions  120  of the first lever  114  function as fixed center point bearings for the lever  114 . The second lever  116  does not have a fixed center point but its triangular side pieces  116   a  and  116   b  are formed with the C-shaped bearing surfaces  123  ( FIG. 39 ). The trunnions  120  are received in corresponding bearing surfaces  123  and can slide back and forth along the straight segments of the surfaces  123  between the curved end segments thereof. As the levers  114  and  116  rotate relative to each other against the contraction force of the spring  118 , a line of force will eventually cross a center point and levers  114  and  116  will continue to rotate in the same direction but now in response to, and with the aid of, the contraction force of the spring  118 . Thus the over-center mechanism  108  can operate with a single spring  118  and produce a similar effect to prior art over center shifting mechanisms requiring both a clutch spring force and a separate reversing force.  
      Flat angled surfaces  14   d  and  14   e  ( FIG. 36 ) on each of the arrow-shaped flat side pieces  114   a  and  114   b  of the first lever  114  respectively engage the flat surfaces  116   d  and  116   e  of the triangular side pieces  116   a  and  116   b  of the second lever  116  to limit the angular rotation between the first lever  114  and the second lever  116 . The flat surfaces  116   d  and  116   e  extend on either side of the C-shaped bearing surfaces  123  ( FIG. 39 ). This architecture of the toggle over-center mechanism  108  ensures that it will not have a locked position or dead spot that would cause the turret  18  and nozzle  17  to stall.  
      The shift disk  122  ( FIG. 67 ) has a main ring-shaped annular portion  122   c  ( FIG. 65 ) with an actuator post  122   d  that extends vertically from a horizontal tab  122   e  that extends horizontally from the annular portion  122   c  opposite the two legs  122   a  and  122   b . The annular portion  122   c  of the shift disk  122  surrounds the narrow lower end of the conical drive basket  106 . Another pair of vertical actuator posts  122   f  and  122   g  ( FIGS. 65 and 67 ) extend vertically from corresponding legs  122   a  and  122   b  of the shift disk  122 . As will be explained hereafter in detail, the actuator posts  122   d ,  122   f  and  122   g  cooperate with tabs  106   d  and  130  to cause the shift disk  122  to actuate the over-center mechanism  108  of the reversing mechanism  26  to shift and cause the turret  18  and the nozzle  17  therein to rotate back and forth between predetermined limits. In this manner, the nozzle  17  ejects a stream of water over a prescribed arc, which is adjustable in size.  
       FIGS. 58-79  illustrate details of the turret coupling assembly  124  that connects the drive shaft  95  of the reversing mechanism  26  to the turret  18  containing the nozzle  17 . The turret coupling assembly  124  includes the inverted conical drive basket  106 . The shift disc  122  works in conjunction with the turret coupling assembly  124  and the over-center mechanism  108  to cause the turret  18  and the nozzle  17  contained therein to rotate back and forth through an adjustable arc. Referring to  FIG. 69  the lower cylindrical end  106   b  of the inverted conical drive basket  106  is splined to the upper end of the drive shaft  95 . The upper ring-shaped end  106   c  ( FIG. 70 ) of the drive basket  106  is formed with a plurality of equally circumferentially spaced vertical drive lugs  107  that fit between mating vertical drive lugs  126   a  formed on the lower end of a cylindrical housing coupling  126  ( FIG. 69 ). A cylindrical adjusting sleeve  128  sits on top of the housing coupling  126 . The adjusting sleeve  128  has a bull gear  128   a  ( FIGS. 69 and 70 ) formed at the upper end thereof. A shift tab  130  ( FIGS. 59, 69 ,  71  and  75 ) extends vertically downwardly from the adjusting sleeve  128  and engages the vertical actuator post  122   d  ( FIG. 65 ) of the shift disk  122  to rotate the same, flipping over the actuating arm  121  ( FIG. 32 ) of the over-center mechanism  108 . A thrust washer  132  (FIG.  69 ) sits on top of the adjusting sleeve  128  and its ribbed outer surface engages a shoulder  134  ( FIG. 4 ) of the inner cylindrical housing  34  of the riser  14 . Upper and lower elastomeric thrust washer seals  136  and  138  ( FIG. 36 ) are co-molded to the rigid plastic thrust washer  132 .  
      The nozzle  17  ( FIG. 4 ) inside the turret  18  ( FIG. 13 ) is part of a unitary plastic molded structure that includes a vertical cylindrical hollow shaft  139  ( FIG. 4 ) that extends through a cylindrical opening  140  ( FIG. 69 ) through the turret coupling assembly  124  and seats inside the upper ring-shaped end  106   c  of the inverted conical drive basket  106 . Water that has mostly flowed around the drive subassembly  32 , and the remainder that has driven the turbine  20 , all eventually flows through the upwardly angled arms  106   a  of the inverted conical drive basket, through the hollow shaft  139  and out the nozzle  17 .  
      The inverted conical drive basket  106  has a vertical shift tab  106   d  ( FIG. 68 ) which extends downwardly from the upper ring-shaped end  106   c . The rotation of the turbine  20  is carried through the gear train reduction  24  and reversing mechanism  26  to turn the drive shaft  95 . The drive shaft  95  turns the turret  18  via the drive basket  106  of the turret coupling assembly  124 . As the turret  18  rotates the actuator post  122   d  ( FIG. 67 ) of the shift disk  122  alternately engages the shift tab  130  ( FIG. 69 ) of the adjusting sleeve  128  and the shift tab  106   d  of the conical drive basket  106 . This rotates the shift disk  122  so that its actuator posts  122   f  and  122   g  ( FIG. 65 ) move the L-shaped actuating arm  121  of the over-center mechanism  108  back and forth, driving the clutch  94  ( FIGS. 9 and 43 ) up and down and reversing the rotation of the turret  18  ( FIG. 13 ).  
      The shift tab  106   d  is the “fixed” arc limit on one end of the adjustable arc whereas the shift tab  130  is the adjustable arc limit. The shift tab  130  extends downwardly from the adjusting sleeve  128  ( FIG. 69 ). The bull gear  128   a  ( FIG. 70 ) at the upper end of the adjusting sleeve  128  may be engaged by a pinion gear  142  ( FIGS. 2, 8  and  88 ) at the lower end of a hollow cylindrical arc adjustment shaft  144 . The adjustment shaft  144  is vertically reciprocable within a cylindrical sleeve  146  formed in the turret  18 . A split drive collect  148  is connected to the upper end of the adjustment shaft  144  and may be engaged by the lower end of the conventional HUNTER® hand tool (not illustrated) to move the arc adjustment shaft  144  downwardly to engage the pinion gear  142  with the bull gear  128   a  ( FIGS. 8 and 88 ). Once the pinion gear  142  and the bull gear  128   a  mesh, the tool is rotated to move the annular position of the shift tab  130  and thereby establish the arc size. The riser  14  of the sprinkler  10  has a ratchet mechanism hereafter described that allows it to be rotated relative to the outer housing  12  in order to ensure that the selected arc coverage is oriented with respect to the turf other landscaping to be watered. Once the position of the shift tab  130  has been set, the arc adjustment shaft  144  is lifted or raised to disengage the pinion gear  142  with the bull gear  128   a . The collet  148  is accessible from the top end of the sprinkler through the cross-hair slits  27   b  ( FIG. 3 ) of the elastomeric cap member  27 . The arc adjustment shaft  144  may be biased by a spring (not illustrated) to its raised position. However, more preferably, the arc adjustment shaft  144  and the collet  148  can be locked in their raised and lowered positions without the need for a spring. See U.S. Pat. No. 6,042,021 of Mike Clark granted Mar. 28, 2000, entitled “Arc Adjustment Tool Locking Mechanism for Pop-Up Rotary Sprinkler”, the entire disclosure of which is hereby incorporated by reference.  
      My sprinkler has a vandal-resistant arc return feature. If a vandal rotates the turret  18  outside of its arc limits, the turret  18  will return to oscillation within its preset-arc limits, so that pavement, windows, people, etc. will not be watered beyond the initial single pass of the nozzle  17 . Referring to  FIG. 64 , the shift tab  106   d  and the shift tab  130  each have a horizontal cross-section that is slightly bent or “dog-legged”. The actuator post  122   d  has a tapered inner wall  150  and the shift tabs  106   d  and  130  are sufficiently flexible in the radial direction so that either shift tab  106   d  or  130  can momentarily bend or defect radially a sufficient amount to ride over and past the wall  150  when the turret  18  is rotated past its arc limits. Thereafter, once the vadal has let go of the turret  18 , the turbine  20  will drive either shift tab  106   d  or  130  until it engages an abutment wall  152  ( FIG. 66 ) on the actuator post  122   d  which is configured so that the shift tab  106   d  or  130   d  cannot radially deflect and move past the same. This causes the shift disk  122  to actuate the over-center mechanism  108 , reversing the rotating of the turret  18 . The turret thereafter continues to oscillate between its originally set arc limits.  
      In some instances it would be desirable to shut off the flow of water through the sprinkler  10  when the irrigation controller is still causing pressurized water to be delivered to the sprinkler  10  so that the riser  14  is in its extended position. This will permit, for example, the nozzle  14  to be replaced with a nozzle providing a different precipitation rate. See for example U.S. Pat. No. 5,699,962 of Loren Scott et al. granted Dec. 23, 1997 entitled “Automatic Engagement Nozzle”, the entire disclosure of which is hereby incorporated by reference. Therefore, the sprinkler  10  is constructed with a pivoting flow stop valve  154  ( FIG. 2 ). The flow stop valve  154  has a rounded perimeter and is curved in cross-section. The flow stop valve  154  pivots within the hollow shaft  139  ( FIG. 2 ) about an axis that traverses its diameter. A spur gear segment  156  ( FIG. 4 ) extends from one side of the valve  154 . A worm gear  158  on the lower end of a valve adjustment shaft  160  engages the spur gear segment  156 . A slotted collet  162  connected to the upper end of the valve adjustment shaft  160  can be engaged by the lower end of the conventional HUNTER® hand tool inserted through the cross-hair slits  27   c  in the elastomeric cap member  27 . The tool can be rotated to turn the valve adjustment shaft  160  to pivot the valve  154  between opened and closed positions. Further details of the flow stop valve mechanism may be found in my allowed U.S. Pat. application Ser. No. 09/539,645 of Mike Clark et al. filed Mar. 30, 2000 and entitled “Irrigation Sprinkler with Pivoting Throttling Valve”, the entire disclosure of which is hereby incorporated by reference.  
       FIGS. 82-96  illustrate an alternate embodiment  164  of my sprinkler which is similar to the sprinkler  10  of  FIGS. 1-81  except that the sprinkler  164  has a scrubber  166  ( FIG. 82 ) that scrapes and cleans dirt, algae and other debris off of a bi-level screen or strainer  168  each time the inner riser  170  vertically extends and retracts. In addition, the inner riser  170  of the sprinkler  164  incorporates a novel ratchet mechanism that allows normally fixes the rotational position of the inner riser  170  within the outer housing  172  but permits the inner riser  170  to be rotated relative to the outer housing  172  to orient the selected arc over the desired area of coverage. The bi-level strainer  168  is formed with a integral ratchet projections in the form of a plurality of rounded projections or teeth  174  ( FIGS. 85 and 96 ) on an upper ring portion  169  ( FIG. 92 ) thereof. Due to the resilient flexible construction of the strainer  168  the teeth  174  can deflect radially inwardly past mating vertical ribs  176  ( FIG. 85 ) molded on the interior wall of the outer housing  172 . This permits the inner riser  170  to be rotated to a fixed position and maintain that position after arc adjustment.  
      The scrubber  166  ( FIG. 82 ) has a vertically split frusto-conical configuration. The lower end of the scrubber  166  has an annular ring  178  ( FIG. 82 ) that snaps into a conformably shaped annular recess in the lower end of the outer housing  172 . The scrubber  166  has multiple vertically extending slits defining resilient arms  180  ( FIGS. 82 and 86 ) each provided at its upper end with a curved wiper blade  182 . The arms  180  firmly press the blades  182  against the strainer  168  as the riser  170  extends and retracts.  
      While I have described a preferred embodiment of my revolutionary rotor type sprinkler with an insertable drive subassembly including a horizontal turbine, it will be apparent to those skilled in the art that my invention can be modified in both arrangement and detail. For example, the Pelton turbine  20  could be replaced with a Francis turbine or a Kaplan turbine, or any other type of turbine heretofore used in conventional rotor type sprinklers. The particular configurations of the gear train reduction  24 , reversing mechanism  26  and over-center mechanism  108  can be varied to suit particular needs.  
      Therefore the protection afforded my invention should only be limited in accordance with the scope of the following claims: