Abstract:
A line marker carries a spray nozzle assembly for marking or painting a line on a horizontal surface. The line marker has a hydraulic circuit which includes a reservoir for holding marking liquid therein and a tank for holding water therein. A pump can pump marking liquid through the spray nozzle during a marking mode of operation or water through the spray nozzle during a flush mode of operation. In the marking mode, at least some marking liquid is recirculated back through the reservoir to help keep the marking liquid in the reservoir agitated and mixed. In the flush mode, water is blocked from entering the reservoir and is recirculated back into the water flow from the tank. In the clean out mode, the hydraulic circuit is operated as if in the marking mode, except that the reservoir is rinsed with an external source of water with the rinse water circulating through the hydraulic circuit and back to the reservoir. At the reservoir, such rinse water is directly conducted by a hose through a drain outlet, thereby speeding the time needed for clean out by avoiding recontamination of the reservoir with rinse water that has already passed through the hydraulic circuit and which is carrying some marking liquid.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of one or more previously filed copending provisional applications identified as follows: Application Ser. No. 60/572,447 filed May 19, 2004. 

   TECHNICAL FIELD 
   This invention relates to apparatus for marking lines or stripes on generally horizontal surfaces, such as sidelines and yardage lines on sports fields, etc. 
   BACKGROUND OF THE INVENTION 
   Line markers, also often called line painters or line stripers, mark lines or stripes on horizontal surfaces. Such markers typically mount a spray nozzle adjacent the front end of the marker. Side shields are sometimes provided on either side of the spray nozzle for spray confinement purposes. As the marker travels over the ground, spray exits from the spray nozzle between the side shields and marks a line on the ground or some other horizontal surface such as a mowed grass surface. 
   One problem with existing line markers is the difficulty in flushing and cleaning the components. Often, many of the components of the hydraulic circuit of the line marker, such as the spray nozzle, valve, liquid supply conduits, etc., must be disassembled for proper cleaning. This is time consuming and messy. Thus, there is a need in the art for a line marker which is easier to flush before short breaks in operation and to clean out before longer breaks in operation. 
   Further, there is a need in line markers to keep the marking liquid held within a reservoir in an agitated and mixed state during line marking operations. Separate agitators have been known for this purpose. However, such agitators add components, complexity and expense to the line marker. There is a need for a simpler and more cost effective way to keep the marking liquid agitated and mixed as it is held in the reservoir awaiting use. 
   SUMMARY OF THE INVENTION 
   One aspect of this invention relates to a hydraulic circuit for a line marker having a spray nozzle for spraying a marking liquid downwardly to mark a line on a horizontal surface. The hydraulic circuit comprises a reservoir for holding a supply of the marking liquid. A pump is provided for pumping the marking liquid from the reservoir and for supplying the marking liquid to the spray nozzle. A selectively operable control valve permits spray of the marking liquid from the spray nozzle when the control valve is in a first state and prevents spray of the marking liquid from the spray nozzle when the control valve is in a second state. A recirculation path is provided for recirculating at least a portion of the marking liquid being pumped by the pump back to the reservoir when the control valve for the spray nozzle is in the second state. 
   Another aspect for this invention relates to a hydraulic circuit for a line marker having a spray nozzle for spraying a marking liquid downwardly to mark a line on a horizontal surface. The hydraulic circuit comprises a reservoir for holding a supply of the marking liquid. A tank is provided for holding a supply of water. An outlet valve draws marking liquid from the reservoir in a marking mode of operation or water from the tank in a flush mode of operation. A pump is provided for pumping whatever liquid passes through the outlet valve to the spray nozzle. 
   Yet another aspect for this invention relates to a method of operating a hydraulic circuit of a line marker, the hydraulic circuit comprising a reservoir on the line marker for holding a supply of marking liquid, a tank on the line marker for holding a supply of water, a pump on the line marker for pumping liquid, and a spray nozzle on the line marker for spraying the marking liquid downwardly to mark a line on a horizontal surface. The method comprises pumping the marking liquid from the reservoir through the pump and to the spray nozzle during a marking mode of operation, and pumping water from the tank through the pump and to the spray nozzle during a flush mode of operation. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     This invention will be described more completely in the following Detailed Description, when taken in conjunction with the following drawings, in which like reference numerals refer to like elements throughout. 
       FIG. 1  is a rear perspective view of a walk behind line marker according to a first embodiment of this invention, particularly illustrating the marking liquid reservoir in an upright operational position; 
       FIG. 2  is a front perspective view of the line marker of  FIG. 1 ; 
       FIG. 3  is a rear perspective view of the line marker of  FIG. 1 , particularly illustrating the marking liquid reservoir in a tipped, drain position for draining unused marking liquid into a five gallon paint bucket; 
       FIG. 4  is a rear perspective view of a riding vehicle line marker according to a second embodiment of this invention, particularly illustrating a five gallon paint bucket positioned beneath the marking liquid reservoir to receive unused marking liquid from the reservoir; 
       FIG. 5  is a partial front elevational view of the line marker of  FIG. 4 , particularly illustrating the operation of the spray nozzle and the sight guide while marking a line; 
       FIG. 6  is a partial front perspective view of the line marker of  FIG. 4 , particularly illustrating the outrigger arm and the spray nozzle carried on the outrigger arm; 
       FIG. 7  is a top plan view of the line marker of  FIG. 4 ; 
       FIG. 8  is a front perspective view of a walk behind line marker according to a third embodiment of this invention, particularly illustrating the outrigger arm and spray nozzle adjacent the left side of the line marker in a rear spray position; 
       FIG. 9  is a left side elevational view of the line marker of  FIG. 8 ; 
       FIG. 10  is a front elevational view of the line marker of  FIG. 8 ; 
       FIG. 11  is a rear elevational view of the line marker of  FIG. 8 , particularly illustrating a five gallon paint bucket positioned beneath the rear of the marking liquid reservoir to receive unused marking liquid from the reservoir; 
       FIG. 12  is a top plan view of the line marker of  FIG. 8 ; 
       FIG. 13  is an exploded perspective view of a portion of the line marker of  FIG. 8 , particularly illustrating the outrigger arm, the spray nozzle, the mounting bracket for mounting the spray nozzle on the outrigger arm, and the side shields for confining the spray from the spray nozzle; 
       FIG. 14  is a front elevational view of what is shown in  FIG. 13 , particularly illustrating the spray nozzle and side shields having been adjusted to spray a relatively wider line; 
       FIG. 15  is a front elevational view similar to  FIG. 14 , particularly illustrating the spray nozzle and side shields having been adjusted to spray a line that is narrower than the line being sprayed in  FIG. 14 ; 
       FIG. 16  is a partial side elevational view of the line marker of  FIG. 8 , particularly illustrating the outrigger arm in a first pivotally adjusted position for carrying the spray nozzle at a first height above the ground; 
       FIG. 17  is a partial side elevational view of the line marker similar to  FIG. 16 , particularly illustrating the outrigger arm in a second pivotally adjusted position for carrying the spray nozzle at a second height above the ground that is higher than the first height shown in  FIG. 16 ; 
       FIG. 18  is a front perspective view of the line marker shown in  FIG. 8 , particularly illustrating the outrigger arm and spray nozzle adjacent the left side of the line marker in a front spray position; 
       FIG. 19  is a side elevational view of the line marker configured in the front spray position shown in  FIG. 18 ; 
       FIG. 20  is a front perspective view of the line marker shown in  FIG. 8 , particularly illustrating the sight guide, outrigger arm and spray nozzle adjacent the right side of the line marker; 
       FIG. 21  is a perspective view of the marking liquid reservoir of the line marker shown in  FIG. 8 , with a portion of the reservoir being broken away to show a reservoir hose as it would be disposed inside the reservoir while operating in a marking mode; 
       FIG. 22  is a perspective view similar to  FIG. 21 , but showing the reservoir hose as it would be disposed inside the reservoir while operating in a clean out mode; 
       FIG. 23  is a perspective view of the hydraulic circuit of the line marker shown in  FIG. 8 , particularly illustrating fluid flow while the hydraulic circuit is operating either in a marking mode or a clean out mode; and 
       FIG. 24  is a perspective view similar to  FIG. 23 , particularly illustrating fluid flow while the hydraulic circuit is operating in a flush mode. 
   

   DETAILED DESCRIPTION 
   The Embodiment of FIGS.  1 – 3   
   A first embodiment of a line marker according to this invention is illustrated generally as  2  in  FIGS. 1–3 . Line marker  2  includes a generally rectangular chassis or frame  4 . A suitable source of power, such as an internal combustion engine  14 , is carried on frame  4 . 
   Frame  4  is supported for movement over the ground by a pair of laterally spaced apart front wheels  6  carried on the front end of frame  4  and by a pair of laterally spaced apart rear wheels  8  carried on the rear end of frame  4 . Wheels  6  and  8  are rotatable about transverse axles that are fixed to frame  4 . In other words, wheels  6  and  8  rotate on the axles to allow frame  4  to roll over the ground, but wheels  6  and  8  do not themselves pivot about a generally vertical axis to permit direct steering of frame  4  through a steering motion of wheels  6  and  8 . Some or all of wheels  6  and  8  could comprise non-steerable caster wheels if so desired, e.g. front wheels  6  could comprise caster wheels. 
   Frame  4  includes a generally U-shaped handle assembly  10  that extends upwardly and rearwardly from the rear end of frame  4 . Handle assembly  10  is much like that found on a lawn mower, handle assembly  10  comprising a pair of laterally spaced apart handle tubes  12  connected to opposite sides of frame  4  with handle tubes  12  being joined together at their upper ends by a transverse crosstube (not shown in  FIG. 1  but shown as  13  in  FIGS. 11 and 12 ). Only a portion of handle assembly  10  is shown in  FIG. 1 , namely the attachment of the lower ends of handle tubes  12  to the sides of frame  4 . Handle assembly  10  allows an operator to walk behind frame  4  during operation of line marker  2  and to guide and manipulate frame  4  by gripping and manipulating handle assembly  10 . 
   Handle assembly  10  allows the operator to turn or steer frame  4  much like an operator turns or steers a walk behind lawn mower. For example, if the operator wishes to turn or adjust the direction of frame  4  towards the operator&#39;s left as the operator stands behind handle assembly  10 , the operator pushes on handle assembly  10  to swing the front end of frame  4  towards the left. Even though wheels  6  and  8  themselves are not steerable, the entire frame  4  executes a turn generally about a point lying on or adjacent the transverse axis that contains the axles of rear wheels  8  of frame  4 . When turning in such a manner, the front end of frame  4  swings or pivots through a much greater range of motion than the rear end of frame  4 . 
   A line marking system is also carried on frame  4 . The line marking system includes a spray nozzle  16  for spraying a marking liquid, a reservoir  18  for holding a supply of marking liquid, and a pump (not shown in  FIG. 1 ) with related connecting conduits or hoses (not shown in  FIG. 1 ) for pumping marking liquid from reservoir  18  to spray nozzle  16 . The pump is driven in any suitable manner from engine  14 . Handle assembly  10  would also carry one or more controls (not shown in  FIG. 1 ) located conveniently close to the operator&#39;s hands for use by the operator for selectively starting and stopping the application of marking liquid through spray nozzle  16 . 
   Spray nozzle  16  is carried on frame  4  through a pivotal, ground following outrigger arm  20 . Outrigger arm  20  is L-shaped having a transverse leg  22  and a longitudinal leg  24 . Transverse leg  22  of outrigger arm  20  is pivotally connected to one side of frame  4  by a fixed pivot hub  26  located on one side of frame  4  between front and rear wheels  6  and  8 . In addition, transverse leg  22  of outrigger arm  20  is provided with a plurality of sets of laterally spaced holes  28  to be able to selectively adjust the distance between the side of frame  4  and longitudinal leg  24  of outrigger arm  20 . 
   A locking pin (not shown) can be dropped down through one set of holes  28  in transverse leg  22  of outrigger arm  20  to prevent leg  22  from being pushed axially inwardly through pivot hub  26 . Transverse leg  22  is long enough to pass all the way through frame  4  and through a matching pivot hub (not shown) on the other side of frame  4 . Then, another locking pin (not shown) can be inserted into a matching set of holes (not shown) on the other end of leg  22  to finish securing leg  22  to frame  4 , i.e. to prevent leg  22  from being pulled axially back out of the hub  26  illustrated in  FIG. 1 . Other ways of pivotally coupling outrigger arm  20  to frame  4  could be used. 
   The rear end of longitudinal leg  24  of outrigger arm  20  carries a rotatable ground engaging wheel  32 . Thus, as frame  4  moves forwardly over the ground, outrigger arm  20  is free to pivot or pitch in either direction about the horizontal axis of pivot hub  26 , as represented by the arrows A and B in  FIG. 1 , to allow the rear end of outrigger arm  20  to move up and down and to follow the contours of the ground. This ground following action of outrigger arm  20  takes place even for very localized changes in ground contour that might not affect frame  4  to the same degree. Longitudinal leg  24  of outrigger arm  20  is long enough so that the axis of rotation of outrigger wheel  32  is located substantially along the axis of rotation of rear wheels  8  of frame  4 , though obviously outrigger wheel  32  is laterally spaced outside of rear wheel  8  carried on that side of frame  4  that mounts outrigger arm  20 . 
   As shown particularly in  FIGS. 1 and 2 , spray nozzle  16  is adjustably carried on outrigger arm  20  to be located between rear wheel  8  on frame  4  and outrigger wheel  32  on outrigger arm  20 . In this respect, an L-shaped cantilever support arm  34  is secured to longitudinal leg  24  of outrigger arm  20  with support arm  34  extending towards the side of frame  4  in front of the gap located between rear wheel  8  and outrigger wheel  32 . A mounting bracket  36  is slidable on support arm  34  and can be clamped in a laterally adjusted position on support arm  34  by a set or thumb screw (not shown) or the like. Thus, mounting bracket  36  can be slid back and forth on support arm  34  in the direction of arrows C and D in  FIG. 3 . 
   A downwardly facing spray nozzle  16  is secured to mounting bracket  36  by an L-shaped mounting arm  38 . The vertical leg of mounting arm  38  passes through mounting bracket  36  to allow spray nozzle  16  to be vertically adjustable towards or away from the surface that is being striped or marked, such surface being depicted by the representation of a plane in  FIGS. 1–3  on which line marker  2  is supported. Again, the vertical leg of mounting arm  38  can be clamped in place on mounting bracket  36  by a set or thumb screw (not shown). The vertical adjustability of spray nozzle  16  is represented by the arrows E and F in  FIG. 2 . 
   The horizontal leg of mounting arm  38  is long enough so that spray nozzle  16  is located on or substantially on the axis of rotation of rear wheels  8  of frame  4 . 
   A sight guide  40  can be provided on frame  4  comprising one or more downwardly facing guide fingers  42 . As shown in  FIG. 1 , a pair of such guide fingers  42  are carried on an arm  44  extending laterally from one side of frame  4 . Guide fingers  42  are slidable along arm  44  relative to each other and can be clamped or locked in place in any suitable manner on arm  44 . Guide fingers  42  are long enough to extend down close to the surface to be marked but terminate slightly above such surface. 
   Arm  44  can either be fixed to frame  4  or can be pivotally carried on frame  4  for pivoting motion about a longitudinal pivot axis (not shown) on frame  4 . When arm  44  is pivotally attached to frame  4 , sight guide  40  can be pivoted upwardly out of the way when desired. The pivoting of sight guide  40  can be done through a lift cable or the like (not shown) extending back to handle assembly  10 . When the operator pulls on the lift cable, arm  44  carrying guide fingers  42  will pivot upwardly on the front end of frame  4  to lift guide fingers  42  up and out of the way as depicted by the arrow G in  FIG. 1 . A stop  46  on arm  44  engages against frame  4  when sight guide  40  is down to define the normal operational position of sight guide  40  as depicted in  FIG. 1 . 
   In using line marker  2  shown in  FIGS. 1–3 , the operator can set a desired width for the line to be marked by adjusting the spacing between rear wheel  8  and outrigger wheel  32 . This is done by adjusting how far outrigger wheel  32  is spaced away from frame  4  using one selected set of locking holes  28 . When the distance between wheels  8  and  32  has been set, then spray nozzle  16  is horizontally adjusted by sliding mounting bracket  36  on support arm  34  to center spray nozzle  16  in the gap between wheels  8  and  32 . If need be, spray nozzle  16  is also vertically adjusted so that the liquid spray exiting nozzle  16  will mark or stripe a line whose width is approximately equal to the distance between wheels  8  and  32 , though spray nozzle  16  could also be vertically adjusted to mark or stripe a line whose width is smaller than the distance between wheels  8  and  32 . The facing surfaces of wheels  8  and  32 , namely the outer side of wheel  8  and the inner side of wheel  32 , are equipped with flat spray shields  48  for spray confinement and wheel protection purposes. Thus, the marking or striping action takes place in the gap between wheels  8  and  32  and such wheels serve to shield or confine the liquid spray. 
   Once spray nozzle  16  is adjusted to provide a desired width of line, guide fingers  42  on sight guide  40  can also be adjusted similarly. In this regard, each guide finger would be adjusted on support arm  34  to be aligned with one edge of the line that is to be marked. For example, the outer guide finger  42  on arm  44  would be slid on arm  44  until the outer guide finger  42  is aligned with the outer edge of the line and then the outer guide finger  42  would be locked in place. The same thing would be done for the inner guide finger  42  except that the inner guide finger would be aligned with the inner edge of the line. Instead of using two guide fingers  42 , only one such guide finger  42  could be used aligned with either the outer or inner edge of the line that is to be marked. 
   After spray nozzle  16  and sight guide  40  are adjusted, the operator can then stand behind frame  4  and grip handle assembly  10  to push and guide frame  4  forwardly in a direction to mark a straight line on a substantially horizontal surface, such as on a paved surface, a turf surface or the like. Frame  4  could be self-propelled from engine  4  using any suitable lawn mower type self propel system. As the operator walks behind the forwardly traveling frame  4 , the operator can use whatever hand control is provided on handle assembly  10  to initiate spraying of the marking liquid held in reservoir  18  through spray nozzle  16 . 
   The operator can use guide fingers  42  on sight guide  40  to help follow and mark a substantially straight line. For example, guide fingers  42  might be used to follow either side of a previously marked but now faded line to enable a new, fresh line to be marked over the faded line. Or, guide fingers  42  might be used to follow a string that marks at least one edge of the desired line. 
   In marking a line, line marker  2  is effective in marking a substantially straight line having a relatively constant width. Spray nozzle  16  is aligned with the axis of rotation of the non-steerable rear wheels  8  on frame  4  which is the axis about which frame  4  pivots when turning. Thus, very little side-to-side motion of spray nozzle  16  will occur even if the operator has to use handle assembly  10  to make some adjustments in the path of travel of frame  4  as the operator attempts to guide frame  4  in a straight path. For example, if frame  4  begins to deviate from its intended course, the operator will have to push on handle assembly  10  to turn frame  4  somewhat to realign guide fingers  42  and thus spray nozzle  16  with the intended direction of travel. However, the rear end of frame  4  along the axis of rear wheels  8  moves very little in such correctional movements and thus the line being marked does not itself appreciably veer or move to the side, which would happen to a much larger degree if spray nozzle  16  were carried on the front of frame  4 . Thus, placement of spray nozzle  16  as shown on the embodiment of the walk behind line marker of  FIGS. 1–3  provides a straighter, less wavy line. 
   In addition, spray nozzle  16  is carried on a separate pivotal outrigger arm  20  such that spray nozzle  16  will move up and down with the contours of the surface over which spray nozzle  16  is passing. This keeps the tip of spray nozzle  16  at a relatively constant distance above the surface. In turn, this ensures that a line of relatively constant width is being sprayed by spray nozzle  16 . Thus, line marker  2  of  FIGS. 1–3  gives a line of more uniform width than many line markers known in the prior art. 
   Reservoir  18  of line marker  2  of  FIGS. 1–3  is pivotally mounted between side brackets  50  on frame  4  for pivotal motion about a substantially horizontal pivot axis  52 . As shown in  FIG. 1 , reservoir  18  has an upper fill inlet  54 , which is shown open in  FIG. 1 , through which a marking liquid can be poured into reservoir  18 . The marking liquid will be drawn through an outlet  56  at the lowermost point of reservoir  18  when the pump is operated to pump the marking liquid through a suitable conduit or hose to spray nozzle  16 . Fill inlet  54  of reservoir  18  is normally closed by a lid or cover  58 , which lid or cover  58  is not shown in  FIG. 1  but is shown in  FIG. 3 . 
   Referring further to  FIG. 1 , reservoir  18  is normally maintained in an upright position in which reservoir  18  is rotated about pivot axis  52  to a forward, generally upright position with the bottom of reservoir  18  resting on a support rail  60  extending between side brackets  50 . The weight of the marking liquid within reservoir  18  as well as the weight of reservoir  18  itself will normally keep reservoir  18  in this normal, upright operational position due to the placement of pivot axis  52  at the rear and upper portion of reservoir  18 . The weight of the marking liquid and the weight of reservoir  18  exerts a torque in the direction of the arrow H tending to maintain reservoir  18  in the orientation shown in  FIG. 1 . 
   However, when it is time to empty reservoir  18  of unused marking liquid after a line marking operation is completed, the operator can grab a handle  62  at the front upper edge of reservoir  18  and tip or rotate reservoir  18  rearwardly about its pivot axis  52 . A drain outlet  64  on the top of reservoir  18  adjacent fill inlet  54  will be rotated with reservoir  18  until drain outlet  64  inclines somewhat downwardly relative to the horizontal in a tipped, drain orientation of reservoir  18  as shown in  FIG. 3 . In this tipped, drain orientation of reservoir  18 , drain outlet  64  is now at or adjacent the lowermost portion of reservoir  18 . Thus, any unused marking liquid remaining in reservoir  18  can drain from reservoir  18  through drain outlet  64  and can be caught in a suitable receptacle. 
   While many receptacles could be used to catch the unused marking liquid draining from reservoir  18 , it is preferred that the receptacle comprise a standard five gallon paint bucket having the usual 15″ height. Thus, the size and shape of reservoir  18 , the location of pivot axis  52  for reservoir  18 , and the location of drain outlet  64  on reservoir  18  are chosen such that drain outlet  64  when inclined downwardly relative to the horizontal will be above the rim of a five gallon paint bucket  66  that is simply sitting on a horizontal surface such as the ground. Thus, in the tipped, drain orientation of reservoir  18  as shown in  FIG. 3 , the lower edge of drain outlet  64  will be at least approximately 15″ high or higher to enable drain outlet  64  to empty into a five gallon paint bucket  66 . This eases cleanup of line marker  2  by permitting easy disposal of marking liquid from reservoir  18  into a standard five gallon paint bucket that is usually readily available and at hand. In addition, the unused marking liquid can then be stored in paint bucket  66  and simply poured back into reservoir  18  through fill inlet  54  the next time line marker  2  is to be used. 
   The Embodiment of FIGS.  4 – 7   
   A second embodiment of a line marker according to this invention is illustrated generally as  2 ′ in  FIGS. 4–7 . Line marker  2 ′ of the second embodiment incorporates numerous component parts which are substantially identical or similar to those employed in line marker  2  of the first embodiment herein. Such component parts have been identified with the same reference numerals utilized herein before, but have been differentiated therefrom by means of prime (′) notations, e.g. line marker  2 ′ instead of line marker  2 . 
   Line marker  2 ′ comprises a riding vehicle having a frame  4 ′ supported by a pair of rear drive wheels  8 ′ and a single front wheel  6 ′ arranged in a tricycle configuration. Rear drive wheels  8 ′ are steerable to change the direction of frame  4 ′ while front wheel  6 ′ is rotatable about a fixed transverse axle. The operator can steer rear drive wheels  8 ′ using a steering wheel  70  located adjacent a seat  72  on frame  4 ′ for carrying the operator. Standard operational controls are also carried on frame  4 ′ adjacent seat  72  to allow the operator to control the traction drive to rear drive wheels  8 ′. Frame  4 ′ carries a power source, such as an internal combustion engine  14 ′. 
   In line marker  2 ′, reservoir  18 ′ is fixed in place on the rear end of frame  4 ′ beneath the operator&#39;s seat  72 . Again, reservoir  18 ′ has an upper, fill inlet  54 ′ normally closed by a lid or cover  58 ′. Reservoir  18 ′ also has an outlet  56 ′ at its lowermost portion for allowing the marking fluid inside of reservoir  18 ′ to be pumped from reservoir  18 ′ by the pump of the line marking system and supplied to spray nozzle  16 ′. 
   In addition, reservoir  18 ′ has a drain outlet (not shown) positioned in the rear or bottom sides of reservoir  18 ′. Reservoir  18 ′ is positioned high enough on frame  4 ′ and frame  4 ′ is itself high enough above the ground that a five gallon paint bucket  66 ′ can be slid beneath the rear end of reservoir  18 ′. When so positioned, the five gallon paint bucket  66 ′ will also be located beneath the drain outlet of reservoir  18 ′. Thus, to drain unused marking fluid from reservoir  18 ′ into bucket  66 ′, the operator need only remove a plug or cap or open a valve on the drain outlet and the unused marking fluid will simply flow by gravity down into bucket  66 ′. This occurs even without having to tip reservoir  18 ′ as in line marker  2  since line marker  2 ′ achieves the same result with a fixed reservoir  18 ′ that is located high enough on frame  4 ′ to allow a bucket  66 ′ to be placed beneath the drain outlet on reservoir  18 ′. 
   In line marker  2 ′, spray nozzle  16 ′ is carried on a pivotal outrigger arm  20 ′ that pivots about a substantially horizontal pivot axis  74  on the front end of frame  4 ′. Outrigger arm  20 ′ has a longitudinal leg  24 ′ and a transverse leg  22 ′. A pair of ground engaging wheels  32 ′ are carried on transverse leg  22 ′ of outrigger arm  20 ′ by a pair of wheel support brackets  76 . Wheel support brackets  76  are slidably mounted on transverse leg  22 ′ of outrigger arm  20 ′ to allow the distance between them to be adjusted. Each of the facing sides of outrigger wheels  32 ′ are provided with planar spray shields  48 ′. Thus, spray nozzle  16 ′ will spray between the two wheels  32 ′ with the planar shields  48 ′ on wheels  32 ′ serving as spray confinement and wheel protection devices. 
   As in line marker  2 , spray nozzle  16 ′ for line marker  2 ′ is also vertically adjustable between outrigger wheels  32 ′ of outrigger arm  20 ′. Spray nozzle  16 ′ faces downwardly and is carried on the vertical leg of a mounting arm  38 ′. The vertical leg of mounting arm  38 ′ passes through a mounting bracket  36 ′ that is fixed to the center of transverse leg  22 ′ of outrigger arm  20 ′. The vertical leg of mounting arm  38 ′ may be locked in a vertically adjusted position by a set screw or set bolt passing through bracket  36 ′ and bearing against the vertical leg of mounting arm  38 ′. The same type of set screw or set bolt may be used to lock each wheel support bracket  76  in laterally adjusted positions on transverse leg  22 ′ of outrigger arm  20 ′. 
   In adjusting spray nozzle  16 ′ of line marker  2 ′, the width of the line being sprayed is established by laterally moving each outrigger wheel  32 ′ on outrigger arm  20 ′ towards or away from spray nozzle  16 ′ until the distance between the two wheels  32 ′ is generally or substantially the same as the width of the line that is to be sprayed. In this regard, spray nozzle  16 ′ remains fixed in place on transverse leg  22 ′ of outrigger arm  20 ′ and the pair of wheels  32 ′ are both adjusted relative to spray nozzle  16 ′ until each wheel  32 ′ is located about the same distance from spray nozzle  16 ′ but on opposite sides of spray nozzle  16 ′. The vertical position of spray nozzle  16 ′ is then adjusted so that the width of the spray as it hits the surface being marked is also approximately equal to the width of the desired line. 
   Spray nozzle  16 ′ in line marker  2 ′ is also positioned along the axis of rotation of the non-steerable front wheel  6 ′ of line marker  2 ′. This means that the operator can correct the direction of line marker  2 ′ to attempt to mark a straight line by steering rear wheels  8 ′ without appreciably affecting the path of motion of spray nozzle  16 ′ and without causing spray nozzle  16 ′ to substantially depart from a straight path. This enhances the ability of line marker  2 ′ to spray a straight, non-wavy line. In addition, because spray nozzle  16 ′ is carried on a pivotal outrigger arm  20 ′, spray nozzle  16 ′ follows the contours of the surface that is being marked to provide a fairly constant line thickness or width. 
   Sight guide  40 ′ of line marker  2 ′ is somewhat different than sight guide  40  in line marker  2 . Sight guide  40 ′ includes a ski-shaped skid  80  carried on the front end of a pivotal arm  82 . Arm  82  pivots at its rear end about the same substantially horizontal axle that carries the non-steerable front wheel  6 . See  FIG. 7 . Arm  82  has an offset angled portion sufficient to allow the front end of arm  82  to be positioned in front of outrigger arm  20 ′ and spray nozzle  16 ′. In addition, skid  80  can also be pivotally mounted on the front end of pivotal arm  82  through any suitable pivot connection  84 . 
   In line marker  2 ′, sight guide  40 ′ also follows the contours of the ground by virtue of the pivotal connection of pivotal arm  82  to frame  4 ′. In addition, skid  80  comprising sight guide  40 ′ can pivot on the front end of arm  82  through pivot connection  84 . The operator can use sight guide  40 ′ to help the operator guide the direction of frame  4 ′ when attempting to mark a straight line. 
   In addition, in line marker  2 ′, the operator&#39;s seat  72  is positioned on frame  4 ′ generally behind or in line with skid  80  and spray nozzle  16 ′, with engine  14 ′ being offset to one side of frame  4 ′. See  FIG. 7 . This allows the operator to clearly see skid  80  and to line up skid  80  with its intended path of travel. This also allows the operator to see and monitor the performance of spray nozzle  16 ′ during line marking. This in line placement of the operator&#39;s seat and the unobstructed view of the operator further enhances the ability of the operator to spray a straight, non-wavy line. 
   The Embodiment of FIGS.  8 – 24   
   A third embodiment of a line marker according to this invention is illustrated generally as  2 ″ in  FIGS. 8–24 . Line marker  2 ″ of the third embodiment incorporates numerous component parts which are substantially identical or similar to those employed in line markers  2  or  2 ′ of the first two embodiments herein. Such component parts have been identified with the same reference numerals utilized herein before, but have been differentiated therefrom by means of double prime (″) notations, e.g. line marker  2 ″ instead of line marker  2  or line marker  2 ′. 
   Line marker  2 ″ shown in  FIGS. 8–24  is a walk behind line marker like that shown in  FIGS. 1–3 . However, instead of having a pair of front wheels  6 , line marker  2 ″ has a single, pivotal, non-steerable front caster wheel  6 ″. The rear wheels  8 ″ are rotatable on a fixed axle or axles carried on frame  4 ″ with rear wheels  8 ″ also not being themselves directly steerable. The operator steers line marker  2 ″ only by pushing on one side or the other of handle assembly  10 ″ to steer line marker  2 ″ like a walk behind lawn mower, e.g. by steering frame  4 ″ about a point on or relatively closely adjacent the rotational axis of rear wheels  8 ″. 
   Outrigger arm  20 ″ of line marker  21 ″ again has a longitudinal leg  24 ″ pivotally connected to frame  4 ″ and a transverse leg  22 ″ which extends laterally of frame  4 ″. Transverse leg  22 ″ carries spray nozzle  16 ″. 
   Longitudinal leg  24 ″ of outrigger arm  20 ″ has an inwardly extending stub shaft portion  23  pivotally carried in a pivot hub  26 ″ on one side of frame  4 ″. Stub shaft portion  23  of longitudinal leg  24 ″ includes elongated slots  86  on the top and bottom thereof with only one such slot  86  shown in  FIG. 13 . Pivot hub  26 ″ includes holes  88  in the top and bottom thereof for receiving a lock pin  89  that passes down through holes  88  and through slots  86 . Lock pin  89  retains outrigger arm  20 ″ within pivot hub  26 ″, but slots  86  allow outrigger arm  20 ″ to be pivotally adjusted on frame  4 ″. 
   A threaded height adjustment rod  90  is carried in a threaded bore  92  on the side of longitudinal leg  24 ″ closest to frame  4 ″. Rod  90  is double headed having an enlarged head  94  on each end. The purpose for making rod  90  double headed will be described later. 
   A wing nut  96  and other jam nuts (not shown) lock rod  90  in a height adjusted position within bore  92 . When wing nut  96  and the jam nuts are loosened, rod  90  can be rotated in one direction within bore  92  to draw rod  90  up within bore  92 . Alternatively, rod  90  can be rotated in the opposite direction within bore  92  to extend rod  90  down out of bore  92 . When rod  90  is in a desired position, wing nut  96  and the jam nuts can be tightened to hold rod  90  in such position. 
   Rod  90  is adjustable within bore  92  to vary or extend the distance between lower head  94  on rod  90  and the underside of outrigger arm  20 ″. Lower head  94  on rod  90  rests on top of a fixed rear stop  98  on frame  4 ″. Since the vertical position of lower head  94  of rod  90  is fixed by rear stop  98 , varying the distance between lower head  94  on rod  90  and the underside of outrigger arm  20 ″ forces outrigger arm  20 ″ to pivot within pivot hub  26 ″ either upwardly or downwardly. Such a pivotal adjustment of outrigger arm  20 ″ adjusts transverse leg  22 ″ of outrigger arm  20 ″, i.e. the portion of outrigger arm  20 ″ that carries spray nozzle  16 ″, to a different vertical height above the ground. 
   The pivotal adjustment of outrigger arm  20 ″ on frame  4 ″ is illustrated in  FIGS. 16 and 17 . As shown in  FIG. 16 , when the distance between lower head  94  of rod  90  and the underside of longitudinal leg  24 ″ is set at a first value l 1 , longitudinal leg  24 ″ of outrigger arm  20 ″ is substantially horizontal relative to the ground to position spray nozzle  16 ″ at a first vertical distance above the ground. If the distance between lower head  94  of rod  90  and the underside of leg  24 ″ is lengthened to become longer as shown by the distance l 2  in  FIG. 17 , then longitudinal leg  24 ″ of outrigger arm  20 ″ is forced by rear stop  98  to incline upwardly relative to the horizontal to raise spray nozzle  16 ″ higher above the ground. The mounting bracket  36 ″ for spray nozzle  16 ″ can be rotated on transverse leg  22 ″ of outrigger arm  20 ″ after such a height adjustment to maintain mounting bracket  36 ″ and the tip of spray nozzle  16 ″ substantially parallel to the ground. 
   Obviously, outrigger arm  20 ″ in line marker  2 ″ is no longer a ground following arm, but is maintained above the ground at a particular fixed position to maintain a desired operational height of spray nozzle  16 ″ relative to frame  4 ″. The height adjustability permits a line having a given width to be sprayed onto a plane arranged at different vertical heights to a reference plance, such as the ground. For example, if a line is being sprayed onto a surface at ground level, then outrigger arm  20 ″ will be adjusted so that the line will be sprayed to its full width just where the spray contacts the ground. But, if the line is desirably being sprayed onto a grass surface which has been mowed to a predetermined height (e.g. 2″ above ground level), then outrigger arm  20 ″ will be raised using rod  90  to raise spray nozzle  16 ″ by the same amount so that the line will be sprayed to its full width at a vertical elevation substantially equal to the height of the grass (i.e. 2″ in the foregoing example). This adjustability also helps keep the lower ends of side shields  48 ″ from dragging through the grass and marring the sides of the marked line, i.e. the sides of the marked line will be sharper and more distinct. 
   Mounting bracket  36 ″ that carries or mounts spray nozzle  16 ″ comprises a downwardly facing U-shaped channel member. Mounting bracket  36 ″ has a pair of spaced side walls  100  that are each split at one end at  102 . Split ends  102  lead to a circular aperture  104  in each side wall  100 . Mounting bracket  36 ″ slides onto the outer end of transverse leg  22 ″ of outrigger arm  20 ″ by passing transverse leg  22 ″ through apertures  104  in side walls  100  of mounting bracket  36 ″. When split ends  102  of mounting bracket  36 ″ are vertically compressed, mounting bracket  36 ″ is clamped or fixed securely to transverse leg  22 ″ of outrigger arm  20 ″. 
   A pair of side shields  48 ″ are adjustably secured to side walls  100  of mounting bracket  36 ″. Each side shield  48 ″ is formed with a transverse slide  106  fixed thereto. Each slide  106  on each shield  48 ″ passes through a pair of aligned square apertures  108  formed on mounting bracket  36 ″.  FIG. 13  shows one aperture  108  in each pair, the other aperture  108  in each pair being similarly located on the other side wall  100  of mounting bracket  36 ″ but being hidden from view in  FIG. 13 . As shown in  FIG. 13 , slide  106  on the outboard side shield  48 ″ passes through the rear pair of apertures  108  while slide  106  on the inboard side shield passes  48 ″ through the front pair of apertures  108 . After passing through their respective pairs of apertures  108 , the outer free ends  107  of each slide  106  will be aligned with a further aperture  110  provided therefor on the other side shield  48 ″. 
   A clamp  112  is provided for clamping mounting bracket  36 ″ on transverse leg  22 ″ of outrigger arm  20 ″ as well as for clamping side shields  48 ″ in laterally adjusted positions on mounting bracket  36 ″. Clamp  112  includes a clamping plate  114  having a first wider section  116  at one end and a narrower tongue  118 . Wider section  116  of clamping plate  114  is wide enough to underlie the bottom edges of side walls  100  of mounting bracket  36 ″ beneath split ends  102  thereof. Narrower tongue  118  of clamping plate  114  fits between side walls  100  of mounting bracket  36 ″ and abuts against the underside of slides  106 . 
   Clamp  112  also includes a plurality of threaded bolts  120 . Bolts  120  extend up through clamping plate  114  and through various holes provided in the top of mounting bracket  36 ″. A wing nut  122  is treaded onto the upper end of each bolt  120  to be able to tighten bolt  120  by drawing bolt  120  upwardly through wing nut  122 . One such bolt  120  is shown in  FIG. 13  with the other bolts  120  omitted from  FIG. 13  for the purpose of clarity. 
   When wing nuts  122  are tightened on bolts  120 , clamping plate  114  is forced upwardly towards the top wall of mounting bracket  36 ″. Two things happen as a result. Wider section  116  of clamping plate  114  squeezes together split ends  102  of side walls  100  of mounting bracket  36 ″ to clamp or secure mounting bracket  36 ″ to transverse leg  22 ″ of outrigger arm  20 ″. Simultaneously, narrower tongue  118  of clamping plate  114  clamps each of slides  106  against the top of apertures  104  in side walls  100  of mounting bracket  36 ″ to also clamp or secure side shields  48 ″ to mounting bracket  36 ″. Obviously, each side shield  48 ″ is first slid to any desired position relative to mounting bracket  36 ″ to adjust the width between side shields  48 ″ before clamping plate  114  is clamped tightly against the bottom of mounting bracket  36 ″. 
   The use of separate bolts  120  and wing nuts  122  on both wider section  116  and narrower tongue  118  of clamping plate  114  allows for release of split ends  102  without necessarily releasing the clamping force on slides  106  of side shields  48 ″. For example, if the operator simply wishes to pivot mounting bracket  36 ″ on transverse leg  22 ″ without changing the position of side shields  48 ″ on mounting bracket  36 ″, only the wing nut  122  on bolt  120  passing through wider section  116  of clamping plate  114  need be loosened. The reverse is also true—the last two wing nuts  122  could be loosened separately from the first wing nut  122  to permit adjustment of side shields  48 ″ without loosening the clamping force holding mounting bracket  36 ″ on transverse leg  22 ″. Obviously, clamping plate  114  could also be split into two separate clamping plates, i.e. a first plate corresponding to wider section  116  and a second plate corresposing to narrower tongue  118 . 
   Spray nozzle  16 ″ is carried on the lower end of a mounting arm  38 ″ that passes downwardly through an aperture in the top of mounting bracket  36 ″ and another aligned aperture in clamping plate  114 . Mounting arm  38 ″ also passes in a relatively close fit through an interior spacer  37  contained within mounting bracket  36 ″. A rotatable set or thumb screw  124  has an inner end  126  that passes through one of side walls  100  of mounting bracket  36 ″ and through an aperture in a near side wall of spacer  37  to engage against the side of mounting arm  38 ″. When set screw  124  is tightened against mounting arm  38 ″ by rotating a knob  128  located outside the side wall of mounting bracket  36 ″, set screw  124  will hold mounting arm  38 ″, and thus spray nozzle  16 ″, in a vertically adjusted position relative to mounting bracket  36 ″ by holding mounting arm  38 ″ against the far side wall of spacer  37 . 
   Preferably, mounting arm  38 ″ comprises a hollow tube to also serve as a conduit for the flow of marking liquid to spray nozzle  16 ″. However, this is not necessary. Mounting arm  38 ″ could be solid with another fluid flow conduit used to carry marking liquid to spray nozzle  16 ″. 
     FIGS. 14 and 15  show different adjusted positions for spray nozzle  16 ″ and side shields  48 ″ to spray lines of different width. Desirably, the spacing between side shields  48 ″ is set in relation to the height of spray nozzle  16 ″ so that the fan shaped spray from spray nozzle  16 ″ spreads out laterally to just cover the distance between side shields  48 ″ at the lower edge of side shields  48 ″. In  FIG. 14 , spray nozzle  16 ″ is raised on mounting bracket  36 ″ and side shields  48 ″ are slid apart on mounting bracket  36 ″ to spray a wider line. Conversely, in  FIG. 15 , spray nozzle  16 ″ is lowered on mounting bracket  36 ″ and side shields  48 ″ are slid towards one another on mounting bracket  36 ″ to spray a narrower line. Once spray nozzle  16 ″ and side shields have been adjusted to provide a line of desired width, transverse leg  22 ″ of outrigger arm  20 ″ can be vertically adjusted upwardly and downwardly as previously described to place such a line onto planes at different elevations relative to the ground, i.e. either at ground level or at planes above ground level. 
   Line marker  2 ″ includes a sight guide  40 ″ comprising a laterally extending arm  44 ″ carried on the front of frame  4 ″ for pivoting about a substantially vertical pivot  43 . A wing nut  130  is provided for locking arm  44 ″ in place on vertical pivot  43 . Arm  44 ″ includes a telescopically adjustable L-shaped outer arm portion  132  having a vertical leg  134 . Again, a thumb or set screw  136  locks outer arm portion  132  in any desired extended position relative to frame  4 ″ to control how far vertical leg  134  of outer arm portion  132  extends beyond the side of frame  4 ″. A ski-shaped skid  80 ″ is vertically adjustable on the lower end of vertical leg  134  of sight guide  40 ″. 
   In using line marker  2 ″ shown in  FIGS. 8–24 , the operator first sets or adjusts spray nozzle  16 ″ and side shields  48 ″ to mark a line of desired width at the bottom of side shields  48 ″. Then, the operator also adjusts the vertical height of outrigger arm  20 ″ above the ground so as to place the marked line at a nominal desired height, i.e. at ground level when marking a paved surface or a few inches above the ground when marking the top of a mowed grass surface. Sight guide  40 ″ is also adjusted by aligning one edge or the other of skid  80 ″ with one side of the line that is to be marked or with a string outlining such a side. 
   With line marker  2 ″ so configured, the operator can then walk behind line marker  2 ″ as spray is being delivered through spray nozzle  16 ″ downwardly to mark the line. As in line marker  2 ″ of the first embodiment, spray nozzle  16 ″ is in a rear spray position that is preferably substantially aligned with (i.e. on or within a few inches either fore or aft of) the rotational axis of rear wheels  8 ″. Thus, any steering mistakes made by the user when guiding line marker  2 ″, or any steering movements needed to correct such mistakes, will not cause spray nozzle  16 ″ to deviate very much from the desired path of the line. This results in a straighter, less wavy line for the reasons enumerated earlier. 
   In some operational situations, having spray nozzle  16 ″ located in a rear spray position on frame  4 ″ is not optimum. For example, assume line marker  2 ″ needs to mark a line all the way up to a fixed object such as a curb or the side of a building. When front wheel  6 ″ of line marker  2 ″ hits such a fixed object, spray nozzle  16 ″ in its rear spray position will still be located well short of the fixed object. Thus, line marker  2 ″ is unable to mark the line all the way up to the fixed object. This is not desirable. 
   In such operational situations, line marker  2 ″ of this invention is designed to allow outrigger arm  20 ″ to be flipped over 180° such that longitudinal leg  24 ″ of outrigger arm  20 ″ now extends forwardly on frame  4 ″ from pivot hub  26 ″ rather than rearwardly. Mounting bracket  36 ″ for spray nozzle  16 ″ is also removed and reinstalled on transverse leg  22 ″ of outrigger arm  20 ″ so that mounting bracket  36 ″ extends forwardly from transverse leg  22 ″ with spray nozzle  16 ″ pointing downwardly towards the ground. When this is done, spray nozzle  16 ″ will be located substantially even or slightly ahead of the front end of frame  4 ″. The front spray position of spray nozzle  16 ″ allows a line to be marked all the way up to a fixed object.  FIGS. 18 and 19  show the front spray position of spray nozzle  16 ″. 
   Obviously, the usual location of sight guide  40 ″ prevents spray nozzle  16 ″ from being placed in the front spray position. However, sight guide  40 ″ is designed to move out of the way to permit such placement. Set screw  136  can be loosened to allow L-shaped outer arm portion  132  to be telescoped into arm  44 ″ and to be rotated approximately 180° so that vertical leg  134  now points upwardly instead of downwardly. Then, wing nut  130  can be loosened to allow arm  44 ″ to pivot rearwardly about its vertical pivot  43 . This permits sight guide  40 ″ to swing rearwardly until L-shaped outer arm portion  132  and skid  80 ″ are nested along and above one side of frame  4 ″ closely adjacent the engine. See  FIG. 18  or  19 . This clears the space that is to be occupied by spray nozzle  16 ″ in its front spray position. Moreover, side shields  48 ″ on mounting bracket  36 ″ can function as sight guides in the front spray position so that sight guide  40 ″ is no longer needed. 
   A front stop  99  similar to rear stop  98  is provided on the side of frame  4 ″ to cooperate with the other head  94  of height adjustment rod  90 , i.e. with what was the upper unused head  94  when spray nozzle  16 ″ was in its rear spray position. When outrigger arm  20 ″ is flipped over and placed into the front spray position, what was the upper head of rod  90  becomes lower head  94  and now cooperates with front stop  99 . Thus, outrigger arm  20 ″ can still be pivoted within pivot hub  26 ″ in the same manner as before to raise or lower the height of spray nozzle  16 ″ above the ground. 
   In some cases, it may be desirable to locate outrigger arm  20 ″, spray nozzle  16 ″ and sight guide  40 ″ on the other side of line marker  2 ″. For example, if a line is to be marked that is parallel to and close to the side of a building which must be approached with the right side of line marker  2 ″ adjacent the building, then spray nozzle  16 ″ would have to be positioned on the right side of frame  4 ″ as opposed to the left side of line marker  2 ″. Thus, a second pivot hub  26 ″, another pair of stops  98  and  99 , and another mount for sight guide  40 ″ are provided on the opposite side of frame  4 ″. This allows alternate placement of outrigger arm  20 ″, spray nozzle  16 ″ and sight guide  40 ″ on the opposite side of frame  4 ″. See  FIG. 20  which shows such alternate placement. 
   Line marker  2 ″ is provided with a hydraulic circuit  140  that includes a reservoir  18 ″ for holding a supply of the marking liquid. Reservoir  18 ″ is shown in  FIGS. 21 and 22  with a portion of reservoir  18 ″ being broken away to show the interior of reservoir  18 ″. Reservoir  18 ″ has an upper fill inlet  54 ″ normally closed by a lid or cover  58 ″. The operator can remove lid or cover  58 ″ and pour marking liquid into reservoir  18 ″ through fill inlet  54 ″. 
   Reservoir  18 ″ has two fittings in the bottom thereof. The first fitting is a reservoir outlet  142  located at the lowest point on reservoir  18 ″ for taking and using the marking liquid from reservoir  18 ″. The second fitting is a reservoir inlet  144  for pumping a liquid, either the marking liquid or a cleaning liquid, into reservoir  18 ″, as will be explained in more detail hereafter. A short length of flexible reservoir hose  146  may be connected to the reservoir inlet  144  to help direct such liquid into or through reservoir  18 ″, again as will be explained in more detail later. 
   In addition to the two fittings provided in the bottom of reservoir  18 ″, a third fitting is provided in a rear wall of reservoir  18 ″. This third fitting is an additional reservoir outlet  148  and is also provided at or adjacent the lowest point of reservoir  18 ″. Reservoir outlet  148  leads to a manually operable drain valve  150  on the rear of reservoir  18 ″. Drain valve  150  has an operating handle  152  to allow the operator to manually open and close drain valve  150 . When drain valve  150  is open, any liquid contained in reservoir  18 ″ will drain through reservoir outlet  148 . 
   As in line marker  2 ″ of the second embodiment, drain valve  150  connected to reservoir  18 ″ has a drain outlet  154  that is high enough to be placed above the rim of a standard 5 gallon paint bucket  66 ″. This is shown in  FIG. 11 . Thus, outlet  154  of drain valve  150  is at least approximately 15″ above the ground. It may also be higher than 15″ as shown in  FIG. 11  where outlet  154  is located a few inches above the rim of paint bucket  66 ″. Thus, line marker  2 ″ can conveniently and advantageously drain unused marking liquid back into paint bucket  661 ″ merely by opening drain valve  150 . 
   Line marker  2 ″ also includes a tank  156  for holding a supply of flush water. Water tank  156  is positioned beneath reservoir  18 ″. Water tank  156  has a removable cap  158  to allow water tank  156  to be filled with water. Thus, line marker  2 ″ carries a sufficiently large onboard supply of water to flush hydraulic circuit  140  of line marker  2 ″. 
   As shown in  FIGS. 23 and 24 , hydraulic circuit  140  includes a pair of interlinked liquid flow control valves beneath the bottom of reservoir  18 ″. These valves comprise an outlet valve  162  connected to reservoir outlet  142  (i.e. to the first fitting of reservoir  18 ″) and an inlet valve  164  connected to reservoir inlet  144  (i.e. to the second fitting of reservoir  18 ″). 
   Outlet valve  162  has a single, continuously open outlet port  166  connected by a first conduit c 1  to the inlet of a pump  168 . In addition, outlet valve  162  has two inlet ports for receiving liquid. One inlet port (not shown) of outlet valve  162  is connected directly to reservoir outlet  142  to be able to pump marking liquid out of reservoir  18 ″. The other inlet port  170  of outlet valve  162  is connected by a second conduit c 2  to water tank  156  to be able to pump water out of water tank  156 . Outlet valve  162  can be selectively shifted by the operator to employ one inlet port or the other at a time, namely outlet valve  162  can be selectively adjusted to pump marking liquid out of reservoir  18 ″ or water out of water tank  156  but does not pump both liquids simultaneously. Outlet valve  162  has a third position in which both inlet ports are closed so that the no liquid can be drawn from either reservoir  18 ″ or water tank  156 . 
   The outlet of pump  168  is connected by a third conduit c 3  to the inlet of a pressure regulator  172 . Pressure regulator  172  has two continuously open outlet ports  174  and  176 . One outlet port  174  of pressure regulator  172  is connected by a fourth conduit c 4  to the inlet of a spray nozzle control valve  178 . The other outlet port  176  of pressure regulator  172  is connected by a fifth conduit c 5  to an inlet port  180  of inlet valve  164 . 
   Inlet valve  164  has two outlet ports. One outlet port  182  of inlet valve  164  is connected directly to reservoir inlet  144 . The other outlet port  184  of inlet valve  164  is connected by a sixth conduit c 6  back to that inlet port  170  of outlet valve  162  which receives water from water tank  156 . Inlet valve  164  is selectively opened or closed by the operator in concert with the operation of outlet valve  162  such that any liquid entering inlet valve  164  is either directed into reservoir  18 ″ or is alternatively sent back to outlet valve  162  through conduit c 6 . Like outlet valve  162 , inlet valve  164  has a third position in which all flow is shut off through inlet valve  164 . 
   A seventh conduit c 7  connects the outlet of spray nozzle control valve  178  to spray nozzle  16 ″ itself. Obviously, conduit c 7  is long and flexible enough to accommodate the three different operational positions of spray nozzle  16 ″ on frame  4 ″ of line marker  2 ″ as shown in  FIGS. 8 ,  18 , and  20 . The operator can selectively open or close spray nozzle control valve  178  by any suitable control mechanism or linkage that is accessible to the user. 
   Outlet valve  162  and inlet valve  164  have previously been described as being interlinked. A control mechanism including a control handle  186  is linked to both of the valves. Control handle  186  extends out through an arcuate slot  188  provided therefor in one side of line marker  2 ″ to be accessible to the user. See  FIG. 20 . Control handle  186  can be moved around the length of slot  188  to select various modes of operation of hydraulic circuit  140 . 
   When control handle  186  is located in a first position in slot  188 , hydraulic circuit  140  is in an “off” mode such that both valves  162  and  164  are closed so that no liquid can pass through either valve. When control handle  186  is located in a second position in slot  188 , hydraulic circuit  140  is in a “marking” mode (or in a “clean out” mode) in which liquid can flow out of reservoir  18 ″ through outlet valve  162  and into reservoir  18 ″ through inlet valve  164 . When control handle  186  has been moved to a third position in slot  188 , hydraulic circuit  140  is in a “flush” mode in which liquid can flow out of water tank  156  through outlet valve  162  and through inlet valve  164  in a loop back to outlet valve  162  but not into reservoir  18 ″. 
   Turning now to the operation of hydraulic circuit  140  in its “marking” mode, the flow in hydraulic circuit  140  is as shown in  FIG. 23 . With pump  168  running, marking liquid is pumped out of reservoir  18 ″ through outlet valve  162 , through pump  168 , and to pressure regulator  172 . From pressure regulator  172 , at least some of the marking liquid is recirculated back into reservoir  18 ″ through inlet valve  164  and another portion of the marking liquid will be made available to spray nozzle  16 ″. However, unless spray nozzle control valve  178  is also opened, no marking liquid will reach spray nozzle  16 ″ and there will be no flow in conduit c 7 . In this event, all of the marking liquid being pumped is in effect continuously recirculating through reservoir  18 ″. 
   Recirculating the marking liquid back through reservoir  18 ″ is desirable to keep the marking liquid in an agitated, fully mixed state. This is enhanced by the short length of reservoir hose  146  provided inside reservoir  18 ″ connected to reservoir inlet  144 . See  FIG. 21 . When this reservoir hose  146  extends and curves over at least a portion of the bottom or reservoir  18 ″, as shown in  FIG. 21 , reservoir hose  146  increases the agitation provided by the recirculated marking liquid over what would occur if reservoir inlet  144  had no such reservoir hose  146  attached thereto. 
   With hydraulic circuit  140  in its “marking” mode and marking liquid being pumped as described above, the operator can selectively start and stop the actual marking of a line by opening and closing, respectively, spray nozzle control valve  178 . When spray nozzle control valve  178  is open, the marking liquid can then also pass through conduit C 7  to spray nozzle  16 ″. Spray nozzle  16 ″ than sprays such marking liquid downwardly to mark a line. While the flow capacity of spray nozzle  16 ″ could equal or exceed the pumping capacity of pump  168 , desirably the flow capacity of spray nozzle  16 ″ is substantially less than the pumping capacity of pump  168  (e.g. ½ gpm spray nozzle capacity vs 4 gpm pump capacity). Thus, a majority of the marking liquid is still recirculated through reservoir  18 ″ even when marking liquid is actually being sprayed from spray nozzle  16 ″ during a line marking operation. 
   There will be times when hydraulic circuit  140  of line marker  2 ″ is desirably flushed to prevent the various components thereof from clogging with dried or partially dried marking liquid. For example, a flush of hydraulic circuit  140  should be done prior to any extended period of inactivity of line marker  2 ″, such as when the operator of line marker  2 ″ temporarily discontinues work and takes a break. Such a flush can be particularly easily and expeditiously accompanied by line marker  2 ″ of this invention when hydraulic circuit  140  is in the flush mode. 
   Turning now to the operation of hydraulic circuit  140  in its “flush” mode, the flow in hydraulic circuit  140  is as shown in  FIG. 24 . With pump  168  running, water is pumped out of water tank  156  through outlet valve  162 , through pump  168 , and to pressure regulator  172 . From pressure regulator  172 , at least some of the water is recirculated through inlet valve  164  and then passes back to outlet valve  162  without entering reservoir  18 ″. Another portion of the water will pass from pressure regulator  172 , through spray nozzle control valve  178 , and then through spray nozzle  16 ″, at least when spray nozzle control valve  178  is open. Thus, in the flush mode, water is taken from water tank  156  and circulated through all the components of hydraulic circuit  140 , save for reservoir  18 ″, as well as the connecting conduits before finally exiting through spray nozzle  16 ″. 
   The operator can perform such a flush operation after first disconnecting outrigger arm  20 ″ from frame  4 ″ of line marker  2 ″. This can be done by pulling lock pin  89  out of pivot hub  26 ″ and by then sliding stub shaft portion  23  of longitudinal leg  24 ″ of outrigger arm  20 ″ out of pivot hub  26 ″. With outrigger arm  20 ″ disconnected, the operator can then lift lid or cover  58 ″ off reservoir  18 ″ and point spray nozzle  16 ″ so that the spray therefrom will pass downwardly into reservoir  18 ″ through fill inlet  54 ″. 
   The operator can then operate hydraulic circuit  140  in its flush mode as described earlier. As water is pumped out of water tank  156 , the water will push the marking liquid ahead of it to first purge hydraulic circuit  140  of such marking liquid. Thus, during the initial purge portion of a flush operation, substantially undiluted marking liquid will first exit from spray nozzle  16 ″ and fall back down through fill inlet  54 ″ of reservoir  18 ″ to rejoin the marking liquid contained in reservoir  18 ″. By observing the character of the spray from spray nozzle  16 ″ as spray nozzle  16 ″ is held over fill inlet  54 ″ of reservoir  18 ″, the operator can tell when the water begins to pass through spray nozzle  16 ″ since the spray will become lighter or more transparent as the marking liquid begins to mix with the water at the end of the initial purge of the marking liquid. The operator then ends the flush operation at this point. As a result, hydraulic circuit  140  has been flushed to clear the valves  162 ,  164  and  178 , pump  168 , pressure regulator  172 , the conduits, etc. of marking material, the purged marking material has been returned to reservoir  18 ″, but no significant amounts of water have been put into reservoir  18 ″. 
   Obviously, hydraulic circuit  140  of line marker  2 ″ of this invention can be easily flushed and cleaned at almost any place and time, even periodically over the course of a day while line marker  2 ″ is far from a maintenance facility. There is no need to have a supply of water on hand since line marker  2 ″ carries its own onboard supply of flush water. There is no need to disassemble or disconnect the various components of the hydraulic system from each other to operate in the flush mode. All that must be done is to place control handle  186  in the position corresponding to the flush mode, which shifts the interlinked outlet and inlet valves  162  and  164  as described above, and then to operate pump  168 . Even outrigger arm  20 ″ is easily removable from frame  4 ″ of line marker  2 ″ to allow spray nozzle  16 ″ to be held over fill inlet  54 ″ of reservoir  18 ″ during operation in the flush mode to return purged marking liquid to reservoir  18 ″. Thus, hydraulic circuit  140  can be flushed with a minimum of effort and mess which is an improvement over the prior art. 
   There will be times when hydraulic circuit  140  of line marker  2 ″ is desirably cleaned out more completely following a flush operation. This might be done at the end of the day or at a time when use of line marker  2 ″ is being discontinued for an extended period of time. In the clean out mode, reservoir  18 ″ is desirably emptied or drained of unused marking liquid and reservoir  18 ″ itself is flushed or cleaned to remove any residue of the marking liquid. 
   In order to perform a clean out operation, the operator might first flush hydraulic circuit  140  as described above in connection with the flush mode of operation. However, this flush step is not essential as the first step in a clean out operation and could be dispensed with if so desired. 
   In every clean out operation, one step that will be performed is to drain any unused marking liquid from reservoir  18 ″. This is done by placing a standard 5 gallon paint bucket  66 ″ beneath outlet  154  of drain valve  150  on reservoir  18 ″. When drain valve  150  is manually opened by the operator, any marking liquid left in reservoir  18 ″ will drain out of reservoir  18 ″ through drain outlet  154  and into paint bucket  66 ″. When the draining operation is complete, the lid of paint bucket  66 ″ can be put back on paint bucket  66 ″ and the unused marking liquid will be conveniently stored in its usual container for reuse at a future time. 
   After the unused marking liquid has been drained from reservoir  18 ″, the operator may then open reservoir  18 ″ by lifting lid or cover  58 ″ off fill inlet  54 ″ of reservoir  18 ″. The operator may then manually redirect reservoir hose  146  into reservoir outlet  148  at the rear of reservoir  18 ″. See  FIG. 24 . Such an orientation of reservoir hose  146  is preferred when hydraulic circuit  140  is placed into its “clean out” mode. 
   With reservoir hose  146  in the position shown in  FIG. 24 , the operator may then place control handle  186  to select the marking mode of operation as described earlier. The operator will also then place an external water hose (not shown) into reservoir  18 ″ through the open fill inlet  54 ″. The external water hose will be connected to a water tap or spigot connected to a high capacity external water source, such as a city water main. The operator will then direct a constant stream of water from this external water source into reservoir  18 ″ using the external water hose to wash out the various interior walls of reservoir  18 ″. 
   As the operator washes out reservoir  18 ″ and with pump  168  running, the water passing into reservoir  181 ″ from this external hose will quickly be pumped out of reservoir  18 ″ by operation of hydraulic circuit  140  in the “marking” mode of  FIG. 24 . This water after passing through hydraulic circuit  140  will then be returned to reservoir  18 ″ through reservoir hose  146  connected to reservoir inlet  144 . However, since reservoir hose  146  has desirably been redirected into the open drain valve  150 , this water will simply be dumped out of reservoir  18 ″ through drain valve  150 . During this type of operation in the clean out mode, line marker  2 ″ will be positioned at a maintenance facility or the like where the water being dumped from drain valve  150  can be directed to a suitable disposal location, i.e. either a floor drain connected to a sewer system where this is permitted or some type of holding tank for containing paint based waste. 
   As in the case of operation in the flush mode, hydraulic circuit  140  can be easily drained of unused marking material and then completely cleaned without having to disassemble or disconnect the components thereof. Reservoir hose  146  in reservoir  18 ″ is desirably redirected into reservoir outlet  148  leading to drain valve  150 , but this is easy to do. The operator must have on hand an external water hose and an external source of water to provide a sufficient volume of water for clean out, but these will be available to most operators of this type of equipment at their maintenance facilities. Hydraulic circuit  140  is then simply operated in the marking mode to discharge the clean out water through reservoir hose  146  in reservoir  18 ″. Thus, the hydraulic flow in hydraulic circuit  140  of this invention is essentially the same in the marking mode or the clean out mode. 
   The marking liquid which is pumped and sprayed in line markers  2 ,  2 ′ preferably comprises a paint, i.e. a liquid containing a pigment which adheres when spread in a thin coat. Other marking liquids or marking materials could be used, though some features of the invention, such as hydraulic circuit  140  described for pumping a liquid, are usable only for liquid marking materials. Other features of the invention are usable with both wet and dry marking materials, e.g. the rear spray position of spray nozzle  16 ″ does not depend upon the nature of the marking material, how side shields  48 ″ adjust, etc. 
   Various modifications of the disclosed embodiments of this invention will be apparent to those skilled in the art. The surface being marked by line markers  2 ,  2 ′ can comprise any more or less horizontal surface, whether paved or unpaved, such as a paved street or parking lot, or an unpaved turf surface such as a baseball, football or soccer field, etc. Thus, the scope of this invention is to be limited only by the appended claims.