Abstract:
This invention is directed to a method of lubricating an object. The method involves the steps of spraying lubricant on a rotating object, and synchronizing the duration of spray to the rotation of the object so that the spray continues only for an interval of spray time corresponding to rotation of the object through a predetermined range of rotation. Apparatus for spraying lubricant on a rotating object is also disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of pending U.S. application Ser. No. 09/382,739 filed Aug. 25, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates in general to fluid dispensing apparatus, and more particularly to a method of and apparatus for lubricating an object by spraying the lubricant on the object. 
     The invention has been developed primarily though not exclusively as a means for efficiently and reliably carrying out in the field the lubrication of threaded connections of drill tubes used to bore long holes used in various operations ranging from oil and gas exploration to communication cable installation, lubrication of the threaded connections facilitating the end-to-end assembly of the drill tubes. Heretofore, lubrication of such connections has generally been carried out either manually or (frequently inadequately) with air-operated pumps. Manual lubrication requires the drilling operator to lose productive time by having to get out of his cab to apply the lubricant to the threaded connection by hand. Application by use of air-operated pumps to spray the lubricant on the threaded connections is generally ineffective to provide a good quality spray at temperatures ranging from +160° F (+71° C.) to −20° F. (−29° C.); at low temperatures air-operated pumps may even become inoperable. The invention has also taken into account the problem that certain zinc or copper-based greases specially formulated for lubricating drill tube connections are very difficult to pump and spray, and the further problem that prior methods of application have sometimes resulted in applying too much or too little lubricant to the connections. 
     SUMMARY OF THE INVENTION 
     Accordingly, among the several objects of the invention may be noted the provision of lubricant dispensing apparatus particularly for reliably and efficiently spraying lubricant on the threaded connections of drill tubes or open gears, even at low temperatures in the field, and enabling use of the aforesaid specially formulated lubricants; the provision of such apparatus which is readily adjustable to dispense or spray charges of lubricant of different selected volumes (ranging, for example, from 0.5 cubic inch to 2.00 cubic inches); the provision of such apparatus which obtains power for a spraying operation solely from pressure of lubricant supplied thereto; the provision of a method of spraying lubricant on a rotating object, including (but not limited to drill tube threads), with the duration of spray being synchronized with the rotation of the object to provide for a more accurate distribution of lubricant on the object; the provision of such a method which is applicable to spraying lubricant on the drill tube of a directional boring machine and other drilling/boring machines; and the provision of apparatus for carrying out the aforementioned method; and the provision of such method and apparatus in which the pattern, pressure, volume and duration of spray are controllable, as required by circumstances; and the provision of such apparatus which is readily mountable on a drilling/boring machine for applying lubricant to the threaded connections of the drill tube sections. 
     While the invention as it has been developed has been embodied in apparatus for spraying a charge of lubricant on a blast drill tube threaded connection, it is to be understood that the principles of the invention are also applicable to dispensing apparatus for fluids other than lubricants, for example sealants and adhesives, and to dispensing apparatus useful in packaging operations for dispensing measured or metered charges of fluid to packages. The term “fluid” as used herein is intended to cover principally any non-gaseous fluid, including viscous fluids such as greases. 
     In general, a method of the present invention involves the steps of spraying lubricant on a rotating object, and synchronizing the duration of spray to the rotation of the object so that the spray continues only for an interval of spray time corresponding to rotation of the object through a predetermined range of rotation. 
     Lubricant spray apparatus of the present invention can be used for spraying a rotating object with lubricant. The apparatus comprises a dispenser for spraying a volume of lubricant adapted for connection in a system for supplying lubricant under pressure to the dispenser for charging it with lubricant to be sprayed. The apparatus further comprises a delivery system for delivery of said volume of lubricant to be sprayed by the dispenser, including a discharge valve adapted to be closed for the charging of the dispenser and to be opened for spraying said volume; and a controller for controlling the timing of the opening and closing of the discharge valve so that the spray continues only for an interval of spray time corresponding to rotation of the object through a predetermined range of rotation. 
     In another aspect, this invention is directed to a directional boring machine for rotating a drill rod comprising a series of separate longitudinal sections having threaded ends for connection of the sections end-to-end. The boring machine comprises a chassis, a system for rotating the drill rod relative to the chassis, and dispensing apparatus mounted on the chassis for spraying lubricant on the threaded end of a drill rod section as it rotates. 
     In one embodiment, a lubrication system of this invention dispenses a lubricant to threads of a drill tube of a horizontal directional boring machine. The lubrication system comprises a pumping system comprising a lubricant reservoir, a pump, an applicator, and a lubricant supply conduit coupled between the pump and the applicator. A controller coupled to the pumping system is operable in response to an operator signal to activate the pumping system to dispense lubricant over a circumferential surface of the threads of the drill tube. 
     In a further aspect, a method of the present invention dispenses a lubricant on the threads of a drill tube held by a chuck of a horizontal directional boring machine. The method comprises rotating the chuck and/or drill tube, dispensing lubricant to the threads of the drill tube, and controlling the dispensing of lubricant to dispense lubricant over a circumferential surface of the threads of the drill tube. 
     In yet a further aspect, a lubrication system of the invention dispenses a lubricant to threads of a drill tube of a horizontal directional boring machine. The system comprises a pumping system comprising a lubricant reservoir, a pump, an applicator, and a lubricant supply conduit coupled between the pump and applicator. A heater is coupled to the pumping system, the heater heating lubricant within the pumping system. A controller is coupled to the pumping system. In response to an operator signal, the controller activates the pumping system to dispense a volume of lubricant from the applicator to the threads of the drill tube. 
     In another embodiment, a lubrication system of the invention comprises a body defining an expansible and contractible chamber, a pump for pumping lubricant to the chamber, a spray nozzle in communication with the chamber, and a device for contracting the chamber to force lubricant out of the chamber and through the spray nozzle at a pressure sufficient to effect spraying of the lubricant, without mixing the lubricant with air under pressure, on a part to be lubricated. 
     In still a further aspect, a directional boring machine of the present invention rotates a drill tube comprising a series of longitudinal sections having threaded ends for connection of the sections end-to-end. The boring machine comprises a chassis, a system for rotating a drill tube section, and dispensing apparatus mounted on the machine for spraying lubricant on the threaded end of the drill tube as it rotates. The dispensing apparatus comprises a body defining an expansible and contractible chamber, a pump for pumping lubricant to the chamber, a spray nozzle in communication with the chamber, and a device for contracting the chamber to force lubricant out of the chamber and through the spray nozzle at a pressure sufficient to effect spraying of the lubricant, without mixing the lubricant with air under pressure, on a part to be lubricated. 
     In another embodiment, a method of this invention involves spraying a part with lubricant. The method comprises pumping lubricant to an expansible and contractible chamber thereby to fill the chamber, and contracting the chamber to force lubricant out of the chamber and through a spray nozzle at a pressure sufficient to effect spraying of the lubricant on the part without mixing the lubricant with air under pressure. 
     Other objects and features will be in part apparent and in part pointed out hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view in elevation of one side of a dispenser of the invention (this side being referred to as the right side); 
     FIG. 2 is a view in plan of the dispenser; 
     FIG. 3 is a view in end elevation of the dispenser as viewed from the right of FIGS. 1 and 2 (a view of what may be referred to as its forward end); 
     FIG. 4 is a view in vertical longitudinal cross section in part (the upper part) on a vertical longitudinal plane through the center of the accumulator and a pressure switch of the apparatus and in part (the lower part) on a vertical longitudinal plane through the axis of a cylinder of the apparatus, these planes being offset one from the other; 
     FIG. 4A is a fragmentary vertical section generally on line  4 A— 4 A of FIG. 6 illustrating a port for entrance and exit of fluid (lubricant) to and from the cylinder; 
     FIG. 5 is a fragmentary horizontal transverse section taken generally on line  5 — 5  of FIG. 3; 
     FIG. 6 is a fragmentary horizontal transverse section taken generally on line  6 — 6  of FIG. 3, showing diagrammatically in phantom an outlet line extending from the outlet of the dispenser to a spray nozzle positioned to spray lubricant on a threaded connection; 
     FIG. 7 is a diagrammatic view of the dispensing apparatus of this invention in its entirety including the dispenser, the system for supplying fluid (lubricant) thereto, the system for delivery of fluid (lubricant) from the dispenser, and the energy accumulator; 
     FIG. 8 is a schematic view illustrating a dispenser of the present invention mounted on the frame of a vertical drilling/boring machine for spraying the threaded end of a drill tube; 
     FIG. 9 is a schematic view illustrating a dispenser of the present invention mounted on the chassis of a horizontal drilling/boring machine for spraying the threaded end of a rotating drill tube; 
     FIG. 10 is a view similar to FIG. 1 showing an alternative embodiment of the dispenser; 
     FIG. 11 is a sectional view along lines  11 — 11  of FIG. 10 showing a heater mounted in the body of the dispenser; 
     FIG. 12 is a sectional view along lines  12 — 12  of FIG. 10; and 
     FIG. 13 is a sectional view similar to FIG. 6 showing the spray nozzle mounted in a separate body remote from the portion of the dispenser containing the piston. 
     Corresponding reference characters indicate corresponding parts throughout several views of the drawings. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings, which illustrate a preferred embodiment of the invention, a dispenser for ejecting a measured volume of fluid on each operation thereof is indicated in its entirety by the reference numeral  1 . The dispenser is adapted for connection thereof and is shown in FIG. 7 as connected in a system designated in its entirety by the reference numeral  3  including a pump P for supplying fluid to be ejected thereby with the fluid so supplied under pressure for charging the dispenser with said fluid to be dispensed. A system designated in its entirety by the reference numeral  5  (FIG. 7) is provided for delivery (ejection) of the stated measured volume of fluid on each actuation of the dispenser. This system  5  includes a discharge valve  7  adapted to be closed for the charging of the dispenser  1  and to be opened for ejection of said measured volume of the fluid by the dispenser  1 . An energy accumulator indicated in its entirety by the reference character A is provided for accumulating energy (power) for actuating the dispenser  1  to eject the stated volume of fluid (the charge), said accumulator being accumulative, i.e., adapted to accumulate, of the stated dispenser-actuable energy in response to the supplying of fluid under pressure to the dispenser for charging it. 
     In the specific aspect of the invention, the fluid which the dispenser  1  is to eject in measured volume on each actuation is a lubricant, such as one of the special greases above mentioned. For blast hole drill tube connection lubrication purposes, the volume may range from 0.5 cubic inch to 2.00 cubic inches, depending upon the size of the threaded connection, the dispenser being constructed in a manner for such volume adjustment as will appear. Broadly, the dispenser is an expansible chamber device having a rearward and a forward aspect and a member  11  movable in the device between a rearward retracted position and a forward position. More particularly, the dispenser  1  (the expansible chamber device) is a cylinder and piston device comprising a body or block  13  having a bottom  15 , top  16 , sides  17  and  18 , side  17  being referred to as the right side, a rearward end  19  and a forward end  21 , the body or block being formed with a cylindric bore  23  (FIG. 4) extending from its rearward end  19  toward but terminating somewhat short of its forward end  21 . The bore  23  is drilled with its axis extending horizontally in the central vertical plane of the body adjacent the bottom  15  of the body and constitutes the cylinder of the cylinder and piston device, said device having piston  11  (the movable part) slidably reciprocal in sealed relation in the cylinder between the retracted position in which it is shown in solid lines in FIG. 4 adjacent the rearward end of the cylinder and a forward position such as shown in phantom in FIG.  4 . The forward movement of the piston from its said retracted to its said forward position may be referred to as its forward delivery or ejection stroke, and its rearward movement from its forward position back to its retracted position may be referred to as its return stroke. 
     As shown, the piston  11  has a central portion  25  of a diameter corresponding to the internal diameter of cylinder  23  and rearward and forward reduced diameter extensions  27  and  29  having slightly enlarged tapered ends. The piston is provided with suitable seals such as indicated at  27   s  and  29   s  surrounding the piston extensions for sealing slidably against the surface of the cylinder  23 . The rearward side of the seal  27   s  and the rearward side of the rearward extension  27  constitute the rearward side or face of the piston; the forward side of the seal  29   s  and the forward extension  29  constitute the forward face or side of the piston. 
     The rearward retracted position of the piston  11  (solid lines, FIG. 4) is determined by engagement of the end of the rearward extension  27  of the piston with a stop  31  at the rearward end of the cylinder  23 . The stop is adjustable axially of the cylinder to vary the retracted position of the piston thereby to vary the volume of lubricant ejected on a delivery or ejection stroke of the piston. As shown, the stop  31  comprises a relatively short length of rod slidable axially with respect to the cylinder in a bore  33  in a fitting  35  threaded as indicated at  37  in the rearward end of the cylinder, the stop (the rod) being backed by an adjusting screw  39  threaded in an axially extending tapped hole  41  in the fitting with a lock nut  43  for locking the screw in axially adjusted position. The forward end of bore  33  is tapered as shown in FIG.  4 . The fitting has a hexagonal head  47  for application of a tool for threading it in the rearward end of the cylinder and is formed for provision of a seal  49  for sealing it in place. A seal  51  is provided for the stop (the rod)  35  in bore  33 . The arrangement is such that by adjusting the screw  39  to hold the stop from backing off (moving rearward) in the fitting  35  from a selected position with respect to the fitting, different selected retracted positions may be determined for the piston, the retracted position being determined by engagement of the rearward end of the rearward extension  29  of the piston with the forward end of the stop and engagement of the stop with the screw  39 . 
     The piston  11  divides the space in cylinder  23  into a forward expansible and contractible chamber  53 , which may be referred to as the first chamber, and a rearward expansible and contractible chamber  55  which may be referred to as the second chamber. The body (or block)  13  has an inlet  57  for lubricant under pressure in its forward end  21  and passaging  59  (FIG. 5) providing communication from the inlet to the stated first or forward chamber  53  in cylinder  23 . The body  13  is adapted for connection thereof and is shown in FIG. 7 as connected in the system, indicated as aforesaid at  3  in its entirety, for supplying lubricant under pressure to the forward (first) chamber  53 , the pressurized lubricant supplied to chamber  53  being operable to drive the piston  11  rearward to its retracted position against the forward end of stop  31  and thereby to expand and fill the forward (first) chamber  53  for a dispensing operation. Thus, pressurized lubricant delivered by pump P (see FIG. 7) to said forward chamber  53  is operable to drive the piston  11  rearward to its retracted position determined by engagement of the piston (more particularly by engagement of the rearward end of piston extension  27 ) with the stop  31 , thereby to expand the forward chamber  53  which becomes filled with lubricant. 
     The above-noted system  3  (diagramed in FIG. 7) for supplying lubricant (the fluid to be ejected) under pressure to the dispenser  1  for ejection thereby is shown primarily to comprise the pump P which takes in lubricant from a lubricant supply indicated diagrammatically at  63  (the lubricant reservoir or container). The pump has an outlet indicated at  65 , which may have an outlet check valve as indicated at  65   v , connected as by the lubricant supply line indicated at  67  to inlet  57  of the dispenser  1  for charging the dispenser. The inlet  57  is at the forward end of the dispenser body. Extending rearward from the inlet in the body is passaging  71  (FIG. 5) leading to cross-passaging  73  including an inlet check valve indicated in its entirety at  75 , from which cross-passaging a passage  77  extends generally tangentially with respect to passage  73  forward from the latter to a vertical passage  79 . Passage  77  is drilled in to passage  79  from the forward end  21  of the body  13  and is provided at its outer end (at the forward end of the body) with a pressure relief valve  81  adapted to relieve pressure in passage  79  should it become excessive-over 4000 psi, for example. Valve  81  is a conventional pressure relief valve such as a Model 90942 valve sold by Lincoln Industrial, of St. Louis, Mo. It will be observed that the vertical passage  79  is offset from the vertical plane of the axis of cylinder  23  toward the right side  17  of the body  13  although appearing in FIG. 4 as in the same vertical plane as said axis in FIG. 4 for convenience of illustration. 
     Passage  79  extends down to a bore  83  (see FIGS. 4 and 6) which extends transversely with respect to the body  13  somewhat forward of the forward end of the cylinder  23 . Bore  83  is drilled into the body  13  from the right side  17  of the body, terminating short of the left side  18 . The vertical passage  79  and bore  83  are coplanar in a vertical transverse plane of the body somewhat forward of the forward end of the cylinder. A fluid pressure (lubricant) switch PS such as a Model 92201-BB3 switch sold by Barksdale of Los Angeles, Calif. is sealingly secured at its lower end on top of the body  13  in a pipe thread  79   c  at the upper end of passage  79 . A passage or port  85  (see FIG. 6) extends rearward from the bore  83  to the forward end of the cylinder  23  providing communication between them. The arrangement is such that lubricant delivered under pressure to the dispenser inlet  57  by the pump P via line  67  flows through passage  71  to passage  73 , opens the inlet check valve  75 , flows through passage  77  to vertical passage  79 , thence via bore  83  and passage or port  85  into the forward end of cylinder  23 . The pressure switch PS, which is normally open, is closed when the pressure reaches a predetermined value. The pressure switch PS may be set at the factory to close at a fixed pressure, or it may be field adjustable to vary the pressure at which the switch closes. 
     As shown in FIG. 5, the inlet check valve  75  comprises a valve seat  87  press fitted into a fitting  91  that is upstream from passage  71 . The fitting  91  is threaded in and closes the outer end of passage  73  and has a bore  93  in which a valve ball  95  is movable into and out of engagement with the seat, being biased to closed position engaging the seat by a coil compression spring  99 . The fitting has a reduced-diameter section  101  providing an annular chamber  103  around said section in passage  73 , the tangential passage  77  extending forward from the lower region of this chamber to said vertical passage  79 . The fitting  91  has radial ports such as indicated at  105  communicating with annular chamber  103 . Seals for the inlet check valve are indicated at  106 . The arrangement is such that lubricant delivered under pressure to the dispenser inlet  57  flows through passage  71  into passage  73 , opens the ball  95  against the bias of spring  99 , flows through the bore  93  of the fitting  91 , and then flows through radial ports  105 , chamber  103  and passages  77  and  79 , bore  83  and passage (port)  85  into the forward end of the cylinder  23  (i.e. into the forward expansible chamber  53  of the cylinder). The forward chamber  53  of the cylinder is thus charged with lubricant, the charge being a metered (measured) volume (or charge) as will be later explained. 
     The system indicated in its entirety by the reference numeral  5  is provided for the flow of the metered (measured) volume of lubricant constituting the charge of lubricant from the forward chamber  53  of the cylinder  23 , i.e. for ejection of said metered volume of lubricant from cylinder  23 , for being sprayed via a spray nozzle  107  (FIG. 6) on a drill tube threaded connection  109  to be lubricated on forward movement of piston  11  from its retracted position through a forward (delivery) stroke. This system includes a lubricant outlet passage  111  in body  13  for flow of lubricant from the forward chamber  53  via bore  83  to a lubricant outlet  113  in the forward end  21  of body  13 , with discharge valve  7  mounted in said bore  83  on the right side of  17  of the body  13 . The spray nozzle  107  is at the end of a lubricant line  117  connected to the lubricant outlet  113 . The line  117  may comprise a short nozzle adapter shown in FIG. 6 or a long line for spraying at a location remote from the body  13 . The spray nozzle can, if so desired, be configured to provide a selected fluid spray pattern, such as nozzle Model No. TP 2500080 TC sold by Spraying Systems Co., of Wheaton, Ill. The spray nozzle preferably has a removable spray tip with an orifice which is sized and configured for providing a desired spray pattern. To change the pattern, the tip is simply replaced with a different tip. The discharge valve  7  is a solenoid valve adapted to be closed when de-energized to block flow of lubricant to the spray nozzle so as to enable the supply of the forward cylinder chamber  53  with lubricant and to be opened on being energized for the delivery of said metered volume of lubricant (the charge) to and through the spray nozzle  107  onto the threaded connection  109  to be lubricated (the point of lubrication). The discharge valve  7 , or accumulator A, among other elements, can be located remote from the body  13  without departing from the scope of the present invention. 
     As shown in detail in FIG. 6 the discharge valve, such as model # SV58-26-0-P-00, manufactured by Hydraforce Inc., of Lincolnshire, Ill., comprises a non-magnetic core  119  having a hexagonal head  121  and a threaded extension  123  threaded in the outer end of the bore  83  with a seal  124 . It further comprises a coil  125  on the core and a magnetic valve member  127  slidable in a bore  129  in the core, the valve member comprising an elongate magnetic rod actuable by energization of the coil having a tapered tip  131  engageable with (and disengageable from) a valve seat  133  lodged in a reduced-diameter inner end of core extension  123  with a seal  137 . The core extension  123  has a reduced diameter section providing an annular chamber  139  in passage  83 . The core extension  123  has radial ports  141  that permit flow of lubricant from the annular chamber  139  to outlet passage  111 . The passage or port  85  provides for communication between the annular chamber  139  and the forward end of the cylinder  23  (the forward chamber  53  of the cylinder). The aforesaid vertical passage  79  extends down to the annular chamber  139 . As shown in FIGS. 1-3 the discharge valve  7  is mounted on the right side  17  of the body  13  and functions to close and open communication between the forward end of the cylinder  23  and outlet  113 . However, in FIG. 7 the discharge valve  7  is shown in line downstream from the body  13  for convenience of illustration. 
     Mounted on top of the body  13  (along with pressure switch PS) is the energy accumulator A, which may also be referred to as a power accumulator, for accumulating energy (power) for driving the piston  11  forward in cylinder  23  through a forward delivery stroke (after expansion and filling of forward chamber  53  of the cylinder) to eject the stated metered volume of lubricant, delivering it through spray nozzle  107 . Accumulator A is accumulative of piston-driving energy (power) in response to the supplying of lubricant under pressure to the forward chamber  53 . For this purpose, the accumulator is a pressurized gas device, which acts to accumulate energy (power) for actuating the piston  11  (the “movable member”) through a delivery stroke in response to the supplying of lubricant under pressure to the forward chamber  53  of the cylinder  23 . Thus, the accumulator A acts like a compression spring, storing energy on compression of the spring, or like a tension spring, storing energy on tensioning thereof, all in response to movement of the piston from its forward to its retracted position on loading of the forward expansible and contractible chamber  53  (with the resultant expansion of the forward chamber  53  and contraction of the rearward chamber  55 ). The accumulator of the present invention may comprise a spring or other alternate type of device for storing energy without departing from the scope of this invention. 
     In detail, the accumulator A comprises a hollow body  145  having what in a broad sense amounts to a movable partition or separator  147  therein dividing the space in the hollow body into an expansible and contractible gas chamber  149  on one side (the top side as illustrated) of the separator and an expansible and contractible chamber  151  for hydraulic fluid such as oil on the other side (the bottom side) of the separator. The movable separator  147  is specifically a flexible diaphragm made of nitrile, for example, with a corrugation for flexibility, and will be so referred to hereinafter. The hollow body  145  is made up of an upper generally cup-shaped or bell-shaped part  153  disposed open end down and a lower generally cup-shaped or bell-shaped part  155  disposed open end up, the diaphragm being sealingly clamped all around its peripheral margin between the open ends of the members  153  and  155 . The cup-shaped parts are held together with the margin of the diaphragm clamped between members  153  and  155 , which are welded together. 
     The gas chamber  149  which is the upper of the two chambers  149  and  151  as the accumulator A is mounted on top of the body  13 , is charged with gas, e.g. nitrogen, under pressure, e.g. 1500 psi, and up to 2000 psi. The upper cup-shaped part  149  has a suitable check valve means such as indicated at  162  at the top for the charging of chamber  149  with the nitrogen (or other gas). This gas charge is a precharge, done at the place of manufacture, and is a permanent charge, sealed in the gas chamber  149  so that further recharging is seldom if ever ordinarily needed. The check valve means  162  is illustrated as having a spring-biased ball check  163  and a screw-threaded cap  164  (resembling a conventional tire valve). 
     Adjacent its rearward end  19  the dispenser body  13  has a vertical passage  165  (see FIG. 4) with a thread  167  at its upper end, this passage extending down to cylinder  23  adjacent the rearward end of the cylinder in the same vertical longitudinal plane as the vertical longitudinal plane of passage  79  (offset to the right of the vertical longitudinal plane of the axis of cylinder  23 ), although appearing in FIG. 4 as being in the same vertical plane as said axis for convenience of illustration. The accumulator A has a necked-down lower end  169  threaded on a tubular fitting  171  in turn threaded in the thread  167  with seals as indicated at  173  for the mounting of the accumulator A on the top of the body  13 . 
     The hydraulic fluid (oil) chamber  151 , the tubular fitting  171 , the lower part of the thread  167  below the lower end of the fitting, the vertical passage  165  and the rearward chamber  55  of the cylinder  23 , are charged with hydraulic fluid such as oil. This charge may be regarded as a permanent charge, effected at the place of manufacture of the dispenser  1  via a charging check valve  174  (FIG. 1) placed in a pipe thread in side  17  of body  13  which connects with passage  165 . The check valve  174  may have a conventional valve ball and spring design, such as Lincoln model 130021-3, and it is arranged to open for the charging operation and to close via spring bias or pressure of hydraulic fluid (oil) in passage  165 . In FIG. 7, there is shown a line  181  for the charging operation, check valve  174  being shown in line  181  for convenience of illustration. 
     A discharge valve  175  (FIG.  4 ), comprising a valve seat  177 , valve ball  179 , and a threaded plug  180  (or set screw), are placed in a threaded hole in rearward end  19  that connects to passage  165 . In normal operation the valve ball  179  is held against seat  177 , and the plug prevents any leakage of fluid. If the accumulator A unit is to be serviced, the hydraulic charge may be released to atmosphere by loosening the plug  180 . This will allow the hydraulic pressure to move the ball  179  off the valve seat  177  and around the ball, out to atmosphere. 
     In dispensing apparatus of this invention for spraying lubricant such as grease on the part to be lubricated, the pump P is what is termed a lance pump for pumping lubricant from a drum containing lubricant, more particularly a pump of the type shown in the co-assigned U.S. patent application Ser. No. 09/151,526 filed Sep. 11, 1998 entitled Pump and especially a pump sold by the assignee&#39;s related company Lincoln Industrial, of St. Louis, Mo., under the trademark FLOW MASTER, Model No. 85483. This pump is driven by a rotary hydraulic motor indicated at  183  in FIG. 7, preferably a rotary hydraulic motor such as a Roller Vane rotor hydraulic motor sold by Parker Hannifin Corp. of Greeneville, Tenn., U.S.A. The hydraulic motor is under control of a solenoid valve  185 . The hydraulic motor has an inlet indicated at  187  with an inlet check valve indicated at  189  and an outlet indicated at  191  (all in FIG.  7 ). A line  193  for supplying the motor with hydraulic fluid under pressure from a source thereof (not shown) is connected to an inlet  194  of the solenoid valve  185  and a line  195  extends from an outlet  197  of the valve to the inlet  187  of the motor. At  199  is shown a hydraulic fluid return line extending from the outlet  191  of the motor  183  back to the source (not shown) of motor-operating hydraulic fluid. This source may be one such as typically associated with drilling operations such as described above, e.g. a standard hydraulic fluid pump operable to pump hydraulic fluid from a sump, with return of said fluid to the sump. The solenoid valve  185  is connected in a line  201  by-passing the motor  183 , the arrangement being such that the solenoid valve, when de-energized, acts to effect a by-pass via  199 ,  201 , the valve and line  197  around the motor  183  as shown in FIG. 7, and when energized acts to deliver hydraulic fluid from the aforesaid source under pressure via line  195  to operate the motor and drive the pump P. 
     Referring to FIG. 7, there is indicated at  203  a controller with which is associated a push button control switch  205  (a manually operable switch) operable to start a cycle of operation of the apparatus to be described. The switch  205  may be an illuminated switch having a lamp under the control of the controller  203 . When energized, the lamp illuminates the switch  205  to indicate that the system is ready to start a cycle of operation. The lamp is de-energized to indicate that the system is not ready to start a cycle, as will be described. A controller which has been used for the apparatus is a “Logo” Model 24R controller sold by Siemens A. G. Automation and Drives Division of Nuremberg, Germany. The controller is connected in a circuit indicated at  207  with the pump-motor-controlling solenoid valve  185 , also connected in a circuit indicated at  209  with the pressure switch PS, and further connected in a circuit indicated at  211  with the discharge valve  7 . The pressure relief valve  81 , which acts to relieve the forward cylinder chamber  53 , passages  85  and  79  and the pressure switch PS of excessive pressure (e.g. 4000 psi) has a lubricant line  213  extending therefrom that is vented to atmosphere. The relief valve  81  is shown in FIG. 7 upstream from dispenser  1  for convenience (rather than at the forward end of the dispenser). It could be located on the left side of the body (at  215 , see FIGS. 1 and 3) in communication with passage  79 , in which case passage  77  is closed at its outer end by a plug. At  217  in FIG. 7 is indicated in phantom a heated enclosure for the dispenser  1  and associated components  7 , PS,  81  and accumulator A. 
     Assuming piston  11  is in its retracted position back against stop  31  (as shown in solid lines in FIG.  4 ), further assuming that the forward cylinder chamber  53  is fully charged with lubricant under pressure, that the discharge valve  7  is closed (holding in the charge), the solenoid valve  185  is de-energized and hence set to block flow of hydraulic fluid from line  193  to the pump motor  183 , that pressure switch PS is closed by the lubricant under pressure (e.g. 3000 psi) in the cylinder  23  and hence in passage  79 , and that the nitrogen gas in the gas chamber  149  of energy accumulator A is under increased pressure over and above its initial pressure, as a result of a previous operation of the apparatus, a cycle of operation of the apparatus may be considered to be initiated by the operator (as in the cab of the drilling equipment) pushing the push button  205  to initiate operation via controller. The controller  203  then acts to carry out a sequence of operations in which, first, the discharge valve  7  is energized and opened by completion of circuit  211  (valve member  127  with its tapered tip  131  is pulled away from seat  133 ) for discharge of lubricant from the cylinder  23 . The piston  11  is driven forward through a delivery stroke by the gas pressure in accumulator chamber  149  acting through the flexible diaphragm  147  on the oil in accumulator chamber  151 , counterbore  107 , passage  79  and the rearward expansible chamber  55  of the cylinder  23 , the piston being driven forward by the act until the forward end of piston extension  29  engages the forward end of the cylinder  23 , which acts as a limit stop determining the length of the delivery stroke. As a result, a metered (measured) charge of lubricant equal in volume to the displacement of the piston  11  in the course of its delivery stroke is ejected from the cylinder  23  and delivered via dispenser outlet  113  and line  117  and the spray nozzle  107  for being sprayed on the threaded connection  109  to be lubricated. The delivery stroke may be regarded as the distance traveled forward by the rearward end of the rear piston extension  27  away from the forward end of stop  31 , and may be set for whatever stroke and hence whatever volume of delivery is desired, within the limits determined by the length of the cylinder. Typically, the cylinder is of such length and the adjustment of the rearward positioning of the stop  31  by the adjustment screw  39  are such as to be capable of effecting metered discharge of volumes of lubricant ranging from 0.5 cubic inch for the most forward position of stop  31  to 2.0 cubic inches for the most rearward position (as shown in FIG. 4) of the stop. 
     On delivery of the metered charge of lubricant from the cylinder  23  for the spraying operation, with the resultant drop in pressure in passage  79 , pressure switch PS opens and breaks circuit  209 . Controller  203  thereupon acts via circuit  211  to close discharge valve  7  to enable recharging the cylinder  23 , and circuit  207  is completed to energize the solenoid valve  185 , the latter shifting to place line  193  in communication with line  195 , thereby supplying the hydraulic motor  183  with hydraulic fluid to drive pump P. The pump P delivers lubricant under pressure via line  67 , inlet  57 , passages  71  and  73 , radial ports  105  (valve ball  95  opening under pressure), annular chamber  103 , passages  77 ,  79  and  85  to the forward chamber  53  of cylinder  23 , lubricant thus charging the cylinder, driving piston  11  back to its retracted position (such as shown in solid lines in FIG.  4 ). When the pressure of lubricant in passage  79  reaches the preset value (e.g. 3000 psi), pressure switch PS closes and this signals the controller  203  via circuit  209  to break circuit  207  and de-energize solenoid valve  185  thereby returning the latter to its condition cutting off flow of hydraulic fluid to motor  183  and stopping pump P. As the piston  11  is driven back to its retracted position, it forces oil out of the rearward chamber of the cylinder  23  and into the oil chamber  151  of the accumulator A thus forcing the flexible diaphragm  147  upward and adding to the compression of the nitrogen gas in gas chamber  149  of the accumulator. Thus, the apparatus resumes the cycle-ready condition (ready for a spray operation) in which piston  11  is in retracted position and cylinder  23  is charged with lubricant, discharge valve  7  is closed holding in the charge, the pump P is off, pressure switch PS is closed, and the accumulator A is ready to supply the energy or force for driving the piston through a delivery stroke on the next cycle by reason of the compressed state of the nitrogen gas in gas chamber  149  of the accumulator. 
     As noted previously, the lamp illuminating the push button switch  205  is also under operation of the controller  203 . The controller turns the lamp on to illuminate the switch  205  (indicating the system is “ready” to spray) when the pump solenoid valve  185  is de-energized to stop the pump, and the controller turns the lamp off (indicating the system is not ready to spray) when the pressure switch PS opens. 
     The duration of the spray during a cycle can be controlled by using a suitable timing mechanism, such as a timer internal to the controller  203 . This timer turns on when the discharge valve  7  is energized and times out a desired spray interval, at the end of which the timer sends a signal to the controller  203  to close the discharge valve and thus stop the spray. The interval timed out by the timer is adjustable so that the duration of the spray can be selected and even synchronized with the motion of an object on which the lubricant is being sprayed. For example, the duration of spray can be synchronized with the rotation of an object being sprayed, such as a rotating shaft having a threaded end, so that the spray continues only for an interval of spray time corresponding to rotation of the object through a predetermined range of rotation. This range may be approximately one revolution of the shaft, thus ensuring that lubricant is applied around the entire circumference of the shaft but not significantly more. For example, for a shaft rotating at 180 rpm or 0.33 second per revolution, the timer could be set to time out a spray duration of 0.33 sec. so that lubricant is applied during only one revolution of the shaft. Alternatively, lubricant could be applied for several revolutions, or only a fraction of a revolution. The spray duration could also be synchronized with other forms of motion, such as linear or curvilinear motion. Also, the controller  203  could operate in an automatic mode in which the successive cycles are started automatically one after another, with a predetermined interval of dwell time between two successive cycles, and the spray duration during each cycle being selected to correspond to a desired range of motion of the object being sprayed. 
     FIG. 8 shows a dispenser  1  of the present invention housed in an enclosure  301  mounted on the frame  305  of a vertical drilling/boring machine  307  adjacent a drill tube  309  rotatable to drill vertical holes, such as vertical blast holes. As shown, the drill tube  309  comprises an upper section having a threaded end  311  for connection to the next section of the series of sections making up the drill tube. The drill tube may remain stationary or rotate as it is sprayed. 
     FIG. 9 shows a dispenser  1  of the present invention mounted on the chassis  331  of a directional boring machine  335  which is equipped with a rotatable chuck  337  for holding and rotating a drill tube  339  (sometimes referred to as a drill rod) to bore a hole in a generally horizontal direction, or some angle off horizontal. In this embodiment, the threaded end  341  of a drill tube section is rotated about the axis of the tube  339  (a generally horizontal or angled axis, for example) as the section is sprayed, and the duration of spray is preferably synchronized with the rotation of the drill tube. The synchronization may be carried out in the manner discussed above, or in any other suitable manner. 
     It will be apparent from the foregoing that the dispenser  1  of the present invention can be adjusted in many different ways to achieve the desired spray patterns. The volume of the spray can be adjusted by adjusting the stop  31 . The pressure of the spray can be adjusted by adjusting the pressure switch PS. The pattern of the spray can be adjusted by using different spray nozzles (tips)  107 . The pattern of the spray can also be varied by adjusting the temperature of the lubricant, as will be explained in more detail below. The duration of the spray and the dwell time between successive cycles can be adjusted by programming the controller  203  according to circumstances. By using some or all of these features, virtually any desired spray condition can be obtained to suit the particular circumstances at hand. 
     FIGS. 10-12 shows an alternative embodiment of a dispenser generally designated  401 , of the present invention. This dispenser is similar to the dispenser  1  previously described (corresponding parts are designated by corresponding reference numbers), except that the dispenser is equipped with a heater  405  received in a bore  407  in the body  13  of the dispenser. The heater is preferably located close to the forward cylinder chamber  53  for heating a charge of lubricant in the chamber. The heater  405  may be a cartridge heater (e.g., a Chromalox ® electric cartridge heater available from Chromalox Product Service of Ogden, Utah) under the control of a thermostat  411  mounted on the body  13  of the dispenser. The thermostat  411  may be set at the factory at a predetermined, non-adjustable temperature, or it may be field adjustable to vary the temperature to which the dispenser body  13  (and lubricant) is heated. The heater is especially useful in cold climates and in other situations where it may be desirable to reduce the viscosity of the particular lubricant being sprayed. 
     The dispenser  401  shown in FIGS. 10 and 12 is also equipped with an indicator, generally designated  421 , for providing a visual indication that the piston  11  is moving between its forward and rearward positions. The indicator comprises a plunger  423  affixed to the rearward end of the piston, as by a retaining clip  425 . The plunger is slidable in a tubular member  427  projecting from the body  13 , the forward end of the tubular member having a threaded connection with a fitting  431  threaded into the body. The arrangement is such that the plunger  423  reciprocates with the piston  11 . The side wall of the tubular member  427  has openings  435  therein which permit visual viewing of the plunger so that a person may determine whether the piston is reciprocating to pump lubricant from the forward chamber. This feature is especially advantageous if it is otherwise difficult to determine whether the dispenser is in operation, as where the spray nozzle  107  is mounted at a location remote from the body  13  of the dispenser. The rearward end of the plunger is engageable with an adjustment screw  441  threaded in the tubular member  427 . This screw  441  has the same function as the stop  31  previously described. The adjustment screw is held in place by a locking screw  443  threaded in the tubular member behind the adjustment screw. 
     FIG. 13 shows an embodiment wherein the spray nozzle  107  is mounted at a location remote from the body of the dispenser. In this embodiment, the spray nozzle and related parts are similar to those described previously (and corresponding parts are designated by corresponding reference numbers), except that the spray nozzle is mounted in a separate body or block  451  having an inlet  453  for supply of lubricant to the nozzle. The inlet  453  is connected to the body of this dispenser by a suitable conduit, such as a flexible hose  455 . The block  451  preferably has a bore  461  in it for receiving a heater  463  at a location adjacent the nozzle  107 . This heater  463  is similar to heater  405  described above and functions to heat lubricant before it is ejected through the nozzle. The heater  463  is controlled by a thermostat, not shown. 
     As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 
     When introducing elements of the present invention or the preferred embodiment(s) thereof, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. 
     In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.