Patent Publication Number: US-2005140138-A1

Title: Locking hydraulic fitting for a dispensing apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
      This application claims the benefit of U.S. Provisional Application No. 60/640,679, filed Dec. 30, 2004, the disclosure of which is hereby incorporated by reference herein in its entirety. This application is also a continuation-in-part of U.S. Ser. No. 10/698,274, filed Oct. 31, 2003, the disclosure of which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD OF THE INVENTION  
      The invention relates generally to dispensing apparatus, and, more particularly, to dispensing apparatus having threaded hydraulic fittings for conveying liquids.  
     BACKGROUND OF THE INVENTION  
      Handheld dispensers have many commercial and industrial applications for dispensing liquids such as hot melt adhesives, sealants and other thermoplastic materials. Handheld dispensers are routinely coupled to a liquid source by a supply conduit that supplies pressurized liquid to the dispenser. A swivel hydraulic fitting is frequently used for rotatably coupling the supply conduit to the dispenser. The swivel hydraulic fitting prevents twisting of the supply conduit and improves the operator&#39;s ability to orient the handheld dispenser relative to the supply conduit.  
      Common swivel hydraulic fittings for a handheld dispenser include a spherical-shaped ball captured in a rotatable engagement with a socket inside a housing, such as the hydraulic fitting disclosed in U.S. Pat. No. 5,507,534. The supply conduit is connected to a coupling located at the free end of a stem having an opposite end coupled with the ball. Defined along the length of the stem is a liquid passageway that extends to approximately the centerpoint of the ball. Radial passageways extend from the liquid passageway to a liquid chamber defined inside the hydraulic fitting that transfers the liquid from the liquid passageway in the stem to the handheld dispenser. As the ball rotates and tilts inside the socket, flow in the liquid pathway defined inside the hydraulic fitting from the supply conduit to the handheld dispenser is uninterrupted and continuous. This type of swivel hydraulic fitting advantageously relieves axially-directed internal forces applied to the ball by the pressurized liquid in the liquid pathway, which reduces binding as the ball tilts and rotates relative to the socket. The swivel hydraulic fitting also has an extended operational life as premature wear of the ball and socket is reduced.  
      Nevertheless, there is still a need for improvements in relation to solving the same or similar axial loading problems arising from axially directed external forces or pull loads applied to the conduit that are subsequently transferred to the swivel member. External axial pull loads are applied to the hydraulic fitting when, for example, the supply conduit snags or catches on objects in the work environment of the operator. External axial pull loads are also applied to the supply conduit by the weight of the supply conduit itself.  
      Another concern with such swivel hydraulic fittings is that threaded components may loosen during use because of torsional forces applied externally to one threaded component, but not to the other threaded component. Typically, these torsional forces are applied to the supply conduit by the axial pull loads experienced as the handheld dispenser is used and are subsequently transferred to the swivel member. As the threaded components loosen, pressurized liquid may leak between the threaded components of the hydraulic fitting.  
      It would be desirable, therefore, to lock engaged threaded components in a hydraulic fitting against torsional forces that, if otherwise unbalanced, would act to loosen the engagement between the threaded components.  
     SUMMARY  
      In one embodiment of the present invention, a lock member includes a collar capable of being positioned between the engaged threaded portions of a hydraulic fitting and a manifold so as to prevent relative rotation between the threaded portions. The collar includes a threaded opening and a portion capable of being engaged with the manifold to prevent relative rotation between the collar and the manifold. The lock member further includes a threaded member having a threaded engagement with the threaded opening. The threaded member has a section capable of being placed in contact with the hydraulic fitting when the threaded portions are engaged so as to prevent rotation between the collar and the hydraulic fitting.  
      In another embodiment of the present invention, a hydraulic fitting for transferring a fluid from a supply conduit to a manifold includes a body having a threaded portion capable of being engaged with a threaded portion of the manifold. The body hydraulically couples a fluid channel of the manifold with the supply conduit when the threaded portions are engaged. The apparatus further includes a lock member configured to prevent rotation of the threaded portions relative to each other, when the threaded portions are engaged. The lock member may be provided as a separate component from the body of the hydraulic fitting. Alternatively, the hydraulic fitting may be provided as a component of a fluid dispenser.  
      In another aspect, a method of transferring a fluid includes mechanically coupling a threaded portion of a hydraulic fitting with a threaded portion of a manifold, hydraulically coupling a first end of a fluid passageway in the hydraulic fitting with a supply conduit, and hydraulically coupling a second end of the fluid passageway with an inlet of the manifold. The method further includes mutually engaging the hydraulic fitting and the manifold with a lock member to prevent relative rotation between the threaded portions.  
      In accordance with the preferred embodiment of the invention, torsional forces applied to the swivel hydraulic fitting, for example from axial pull loads, do not result in loosening of threaded components in the fitting. Instead, the relative rotation of these threaded components is prevented by the implementation of a lock member. Consequently, torsional forces created when the dispenser is moved are ineffective for loosening the tightened threaded components.  
      These and other benefits and advantages of the present invention shall become more apparent from the accompanying drawings and description thereof. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
      The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the principles of the invention.  
       FIG. 1  is a side perspective view of a dispensing handgun incorporating a swivel hydraulic fitting constructed in accordance with the principles of the invention;  
       FIG. 2  is a cross-sectional view of a portion of  FIG. 1  taken generally along the mid-plane of  FIG. 1  in which an outward axial force is applied to the stem;  
       FIG. 3  is a cross-sectional view similar to  FIG. 2  in which an inward axial force is applied to the stem;  
       FIG. 4  is an exploded view of a portion of the swivel fitting of  FIG. 1 ;  
       FIG. 5  is a top view in partial cross-section taken along line  5 - 5  of  FIG. 1 ; and  
       FIG. 6  is a top view in partial cross-section taken along line  6 - 6  of  FIG. 1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
      With reference to  FIGS. 1 and 2 , a handheld dispenser  10  generally includes a body  12  housing a fluid manifold  14  with an internal fluid channel or pathway  13  leading to a nozzle tip  16 , which has an internal fluid channel coupled with the fluid pathway  13  and an exit orifice from which fluid or liquid is dispensed from the fluid channel. A handgrip  20  of the dispenser body  12  is shaped to be grasped by a human hand for moving the handheld dispenser  10  to orient the nozzle tip  16  relative to an object receiving the dispensed fluid or liquid. Handheld dispenser  10  may be operated in a vertical orientation, a horizontal orientation, or any intermediate orientation between vertical and horizontal.  
      References herein to terms such as “vertical”, “horizontal”, etc. are made by way of example, and not by way of limitation, to establish a frame of reference. It is understood various other frames of reference may be employed for purposes of describing the invention without departing from the spirit and scope of the invention.  
      Positioned in the fluid pathway  13  defined inside the fluid manifold  14  is a valve element (not shown) movable between opened and closed conditions to permit liquid flow through the internal fluid pathway  13  to the channel and exit orifice of nozzle tip  16 . This affords an operator the ability to regulate and interrupt the stream of liquid dispensed from the handheld dispenser  10 . The valve element is operated by manually actuating or otherwise depressing an external trigger  18  in reaction to which the valve element moves to the opened condition for permitting liquid to flow to the nozzle tip  16 , and be dispensed, as a spray or stream from the exit orifice in the nozzle tip  16 . The flow volume through the fluid pathway  13  to the nozzle tip  16  may be regulated by the degree to which the operator depresses trigger  18 . Releasing the trigger  18  discontinues the flow of liquid through the fluid pathway  13  of the fluid manifold  14  to the nozzle tip  16  and provides the closed condition.  
      A supply hose or conduit  22  is removably attached to the handheld dispenser  10  by a female hydraulic coupling element  24  for connecting with a complementary male hydraulic coupling element  26  ( FIG. 2 ) of a hydraulic fitting  28  constructed in accordance with the principles of the invention. The hydraulic coupling elements  24 ,  26  are preferably threaded coupling members. Liquid is pumped or otherwise supplied from a pressurized liquid source to the fluid manifold  14  of the handheld dispenser  10  through an internal lumen extending along the length of the supply conduit  22 . Supply conduit  22  may be insulated and/or heated for reducing radially-outward heat transfer that would otherwise cool heated liquids flowing through the internal lumen and may also include temperature sensing. The liquid supplied to the handheld dispenser  10  by supply conduit  22  may be, for example, a heated thermoplastic material or a hot melt adhesive.  
      The principles of the invention may also be applicable to other types of handheld dispensers including, but not limited to, paint spray applicators, fuel dispensers and pneumatic tools. Other types of non-handheld dispensers supported by a structural framework may also benefit from application of the principles of the present invention.  
      With reference to  FIGS. 1-3 , the hydraulic fitting  28  generally includes a swivel member  30 , a main body or housing  32 , and a dome-shaped cap  34  having an internally-threaded portion  36  that attaches to an externally-threaded portion  38  of the housing  32 . The threaded attachment of the cap  34  to the housing  32  secures the swivel member  30  within the housing  32 . Another threaded portion or region  40  on the housing  32  mates with a threaded portion  41  of the fluid manifold  14 , preferably defined by the threads on an internally-threaded inlet  42  to the internal fluid pathway  13  of the manifold  14 . Inlet  42  is defined on a neck  43  projecting from the fluid manifold  14 . A circumferential shoulder  44  defined in housing  32  adjacent to the externally threaded portion  38  defines a stop that limits tightening of the cap  34 .  
      The swivel member  30  includes a spherical-shaped ball member or ball  46  and a stem  48  having a leading end extending into a bore  50  extending through the ball  46 . A portion of the stem  48  projects from the housing  32  so that hydraulic coupling element  26  can be connected with hydraulic coupling element  24  of supply conduit  22 . Stem  48  is axially-movable over a limited range of axial movement relative to the ball  46 , as detailed below. The swivel member  30  and portions of the housing  32  surrounding the ball  46  constitute a ball-in-socket joint, as appreciated by persons of ordinary skill in the art, in which the stem  48  is movable relative to the housing  32  independent of the ball  46 .  
      Ball  46  is mounted within the housing  32  for rotation and limited angular displacement relative to the housing  32 . To that end, a socket assembly situated inside a fluid cavity  52  defined inside the housing  32  includes an upper cup-shaped socket  54  carrying a circumferential, concave bearing surface  56  and a floating sealing member  58  carrying another circumferential, concave bearing surface  60 . The generally confronting bearing surfaces  56 ,  60  each have a surface area that contacts a convex outer surface  62  of the ball  46  for guiding the swivel member  30  as it rotates and tilts relative to the housing  32 . The curvature of the convex outer surface  62  of the ball  46  corresponds to the curvature of the concave bearing surfaces  56 ,  60 .  
      The stem  48  and ball  46  are freely rotatable through a continuum of multiple different angles, typically by a full 360°, relative to the stationary housing  32 , as indicated by the double-headed arrow labeled with reference numeral  33  ( FIG. 1 ), about a swivel axis extending along the length of stem  48 . The stem  48  and ball  46  may also be freely tilted or pivoted relative to the housing  32  through a plurality of angles, as indicated by the double-headed arrow labeled with reference numeral  35  ( FIG. 1 ). Typically, the stem  48  and ball  46  are capable of tilting through an angle of less than about 20°, although the present invention is not so limited. The supply conduit  22  and hydraulic coupling element  24  move along with the stem  48 . The hydraulic fitting  28  may assume various different angles and rotational orientations as the dispenser  10  is grasped by handgrip  20  and moved by the operator to orient the nozzle tip  16  relative to the object receiving the dispensed liquid.  
      With reference to  FIG. 2 , resilient elastomer o-rings  70 ,  72  held within annular grooves  74 ,  76  inscribed about a circumferential portion of a corresponding one of the bearing surfaces  56 ,  60  and compressed against the convex outer surface  62  of the ball  46  provide fluid-tight dynamic fluid seals as the swivel member  30  rotates and tilts. The annular grooves  74 ,  76  are oriented angularly relative to the ball  46  so that each has a mouth that opens toward the convex outer surface  62  and radially relative to the center point of ball  46 . The axial spacing between the socket  54  and floating sealing member  58  is such that the ball  46  has a dynamic sliding fit with o-rings  70 ,  72 . The annular grooves  74 ,  76  in bearing surfaces  56 ,  60  and o-rings  70 ,  72  cooperate to provide an efficient fluid sealing action against the ball  46  without appreciably impairing relative rotation and tilting between the ball  46  and the socket assembly. An elastomer o-ring  78  received in an annular groove  80  encircling an outer surface of sealing member  58  is compressed against an inner surface  82  of the housing  32  to provide a static fluid seal.  
      Extending radially outward from a first portion  48   a  of the stem  48  of swivel member  30  is an annular flange  84  having a convex curved surface  86  facing toward an inwardly-facing concave surface  88  of the dome-shaped cap  34 . A bearing component  90  inserted into the space defined between the curved surfaces  86 ,  88  has a curvature that conforms to the curvature of each of the curved surfaces  86 ,  88 . The bearing component  90  may be a gasket or a coating applied to one or both of the curved surfaces  86 ,  88 . Preferably, the bearing component  90  is a gasket that is stationary relative to the movement of the flange  84 .  
      With continued reference to  FIG. 2 , bearing component  90  is formed of a material having a relatively low coefficient of friction with the material forming the annular flange  84  so that the effect of friction on movement of the flange relative to the stationary cap  34  is reduced. Specifically, the coefficient of sliding or kinetic friction of the material forming bearing component  90  against the material forming the annular flange  84  is less than, and preferably significantly less than, the coefficient of kinetic friction between the materials forming the curved surfaces  86 ,  88 , usually a steel on steel contact. The material forming bearing component  90  should be stable at the temperature of the dispensed liquid, which transfers heat to the hydraulic fitting  28  if the liquid is heated. The material forming the bearing component  90  may be, for example, a wear resistant polymer such as polytetrafluoroethylene (PTFE), the homopolymer of tetrafluoroethylene sold under the trademark TEFLON by DuPont (Wilmington, Del.), or Rulon®, which is a filled form of tetrafluoroethylene.  
      Extending axially along the length of the stem  48  is a liquid passageway  94  that communicates with a plurality of cross-drilled radial passageways  96  that transfer liquid to an annular liquid cavity  98  defined in an inwardly-facing cylindrical side wall  100  defining bore  50  in which a second portion  48   b  of stem  48  is received. Opposite ends of the side wall  100  are chamfered. The radial passageways  96  communicate with the liquid cavity  98  for all possible orientations of the hydraulic fitting  28 . Radial passageways  102  extending through the ball  46  transfer liquid from the liquid cavity  98  to fluid cavity  52  inside the housing  32 . Extending through socket  54  are radial passageways  104  that transfer liquid from the fluid cavity  52  to a liquid passageway  106  extending axially through a neck  108  of socket  54 . The liquid passageway  106  couples the hydraulic fitting  28  with the internal fluid manifold  14  of the handheld dispenser  10 .  
      With continued reference to  FIG. 2 , the outer diameter of the second portion  48   b  of the stem  48  is smaller than the diameter of bore  50  so that stem  48  has adequate clearance to freely move within bore  50 . Spaced along the axial length of the stem  48  are two inscribed circumferential grooves  110 ,  112  each holding one of a corresponding pair of resilient elastomer o-rings  114 ,  116 , which are compressed against the inwardly-facing cylindrical side wall  100  surrounding bore  50 . The respective mouth of each groove  110 ,  112  opens toward the cylindrical side wall  100  and the o-rings  114 ,  116  are dimensioned relative to the grooves  110 ,  112  so that, when uncompressed, a portion of each o-ring  114 ,  116  projects above the lip of the open mouth. When compressed by contact against the ball  46  in the assembled state, the o-rings  114 ,  116  preferably space the ball  46  from the stem  48  so that the cylindrical side wall  100  and the second portion  48   b  of stem  48  have a non-contacting relationship.  
      The axial travel range of the stem  48  relative to the ball  46  is limited by contact, at an inward extremum of the travel range, between a shoulder  118  defined at the junction between the portions  48   a,b  of stem  48  and the convex outer surface  62  of ball  46  and by contact between the curved surfaces  86 ,  88  at an outward extremum of the travel range. If the stem  48  is pushed inwardly relative to the ball  46  by an inwardly-directed axial force, generally indicated by reference numeral  119  on  FIG. 3 , applied to the supply conduit  22  ( FIG. 1 ) and stem  48 , shoulder  118  contacts the convex outer surface  62 . As a result, the leading tip of first portion  48   a  of the stem  48  cannot protrude beyond the convex outer surface  62  of the ball  46  and the radial passageways  96  remain in constant fluid communication with the liquid cavity  98 .  
      If the stem  48  is pulled outwardly relative to the ball  46  by an outwardly-directed axial force, generally indicated by reference numeral  121  on  FIG. 2 , applied to the supply conduit  22  and stem  48  the curved surfaces  86 ,  88  contact and halt outward movement or withdrawal of the stem  48 . As a result, the applied axial force  121  is transferred from the stem  48  to the cap  34 , as diagrammatically indicated by arrow  123 , and subsequently to the housing  32  and ultimately to the dispenser  12  as the dispenser  12 , housing  32  and cap  34  comprise a unitary structure. Fluid communication is continuous between the radial passageways  96  and the liquid cavity  98  as the stem  48  moves inward and outward. Under normal working conditions, the stem  48  will be pulled outwardly relative to the ball  46 , as the weight of the supply conduit  22  will apply an uninterrupted outward axial force to the stem  48 . Additional axial forces may be applied to the stem  48  when the supply conduit  22  snags or catches against external objects in the operator&#39;s work environment.  
      The action of the stem  48  in response to the outward axial force  121  ( FIG. 2 ) isolates the ball  46  so that the axial force  121  applied in an outward direction is not transferred to the ball  46 . Instead, outward axial forces are transferred from the stem  48  to the cap  34  and transferred serially to the housing  32  and dispenser  12 , which collectively constitute a rigid body that dampens the outward axial force applied to stem  48 .  
      Hydraulic fitting  28  has a construction that is compatible with dispensing fluids like hot melt materials that are converted, when heated, from a room-temperature solid to a liquid state. However, it should be understood that the methods and apparatus of the present invention are believed to be equally applicable for use in connection with the dispensing of other heated and unheated fluids. In addition, the principles of the invention may be applicable to hydraulic fittings having a construction that does not permit tilting, rotation, or both movements.  
      In use and with reference to  FIGS. 1 and 2 , liquid is directed along the length of the stem  48  through liquid passageway  94  and flows through radial passageways  96  in the stem  48 , the annular liquid cavity  98 , the radial passageways  102  in ball  46 , the fluid cavity  52 , and the radial passageways  104  in socket  54  to the liquid passageway  106  coupling the hydraulic fitting  28  with the internal fluid manifold  14  of the handheld dispenser  10 . As the operator moves about carrying the handheld dispenser  10 , the hydraulic fitting  28  rotates and tilts to accommodate changes in orientation while retaining an open fluid path so that liquid flow is uninterrupted to the handheld dispenser  10 .  
      Axial forces  121  ( FIG. 2 ) pulling on stem  48  cause the stem  48  to move outwardly relative to the ball  46 , while the o-rings  114 ,  116  maintain a fluid-tight seal with the sidewall  100  surrounding bore  50 . The axial forces  121  are transferred from the stem  48  to the cap  34  by contact between the curved surfaces  86 ,  88 , as mediated by bearing component  90 , and subsequently through the housing  32  to the handheld dispenser  10 . More specifically, axial forces  121  applied to the stem  48  are transferred from the flange  84  to the dome-shaped cap  34  through the threaded engagement between the threaded portions  36  and  38 , through the housing  32 , and through the threaded engagement between the threaded region  40  and the threaded inlet  42  to the handheld dispenser  10 . As a result, such axial forces  121  applied to the stem  48  are not transferred with a significant magnitude or at all to the ball  46 , which reduces the forces applied to the o-rings  114 ,  116  and operates to extend the longevity of the o-rings  114 ,  116 . In particular, the operating lifetime of o-ring  116  is lengthened, as the predominately applied outward axial force  121  that would otherwise have been transferred to o-ring  116  is instead transferred by the flange  84  to the cap  34 .  
      With reference to  FIGS. 1, 2 ,  4 ,  5 , and  6 , an annular lock member  120  is positioned between the dispenser body  12  and the hydraulic fitting  28 . The lock member  120  operates to prevent unwanted relative rotation and loosening between the threaded region  40  on the housing  32  and the internally-threaded inlet  42  of the fluid manifold  14 . A collar  122  of the lock member  120  includes a stepped-diameter central bore  124  through which the threaded region  40  is engaged with the internally threaded portion of inlet  42 .  
      The collar  122  is registered angularly relative to the neck  43  such that bosses or surfaces, preferably flats  126  ( FIG. 5 ), defined in the material of lock member  120  and positioned inside the circumference of a smaller-diameter portion  124   a  of bore  124  have a contacting relationship with corresponding bosses or surfaces, preferably flats  128 , defined on the exterior of the neck  43 . Contact between the surfaces of flats  126  and  128  prevents relative rotation between the fluid manifold  14  and the lock member  120 . Flats  126  and  128  have corresponding angular spacings about the circumference of the bore  124  and neck  43 , respectively, so that flats  126 ,  128  may be placed into alignment during assembly and installation. The portion  124   a  of bore  124  has a non-circular cross section that is interrupted by the presence of flats  126 .  
      In the illustrated embodiment, a pair of flats  126  are substantially equivalent and diametrically-opposed, as well as a pair of flats  128  that are substantially equivalent and diametrically-opposed, so that the flats  126 ,  128  may be keyed and mutually engaged at two different angular orientations between neck  43  and a nut  130 . That is, flats  126  lie in approximately parallel planes, as do flats  128 . However, the invention is not so limited as, for example, three flats  126  may be provided within bore  124  and three flats  128  of corresponding relative angular spacing, preferably equal angular spacing, may be provided on neck  43 .  
      The housing  32  of hydraulic fitting  28  includes integral nut  130  having faces  132  arranged about the circumference at locations suitable for grasping nut  130  with a tool for rotating the hydraulic fitting  28  relative to the fluid manifold  14  to tighten or loosen the threaded engagement between the threaded region  40  and internally-threaded inlet  42 . In the illustrated embodiment, a plurality of six faces  132  are defined with a hexagonal arrangement about the circumference of nut  130 . Although this provides compatibility with conventional tools used to engage nut  130  for tightening and loosening the threaded engagement between threaded region  40  and internally-threaded inlet  42 , the number of faces  132  may differ and other arrangements are possible.  
      Spaced along a central axis  134  of bore  124  from portion  124   a  is an adjacent portion  124   b  of larger diameter than portion  124   a  and having a circular cross section. The nut  130  is partially positioned inside this larger-diameter portion  124   b  and, in particular, the faces  132  of nut  130  are at least partially positioned inside portion  124   b . The diameter of portion  124   b  may be approximately equal to the diameter of a circle circumscribing nut  130 , as shown in  FIG. 5 , or may be larger than the diameter of the circumscribing circle to provide additional clearance.  
      A threaded member, such as a set screw  136 , penetrates through a threaded opening  138  defined in the side of the circular cross-section portion ( FIG. 5 ) of collar  122 . A tip  140  of the set screw  136  contacts one of the faces  132  on the integral nut  130 . The specific face  132  contacted by a tip  144  of set screw  136  will depend upon the angular orientation of nut  130  relative to the location of the set screw  136 . Typically, the faces  132  are substantially identical and any may be beneficially contacted by tip  144  when the set screw  136  is advanced to contact one of faces  132 . The set screw  136  has a conventional head that may be engaged by a suitable tool for tightening and loosening the set screw  136 .  
      The opening  138  is oriented relative to the central axis  134  of the bore  124  such that a centerline  140  extending along the length of a threaded shank or portion  142  of the set screw  136  does not intersect the central axis  134  of bore  124 . In other words, the centerline  140  along which the set screw  136  advances and withdraws is offset from the central axis  134  so that the central axis  134  and centerline  140  do not intersect. As a result, the set screw  136  provides a torque or torsional force on the nut  130 . The torsional force applied by the tip  140  of set screw  136  to the face  132  of nut  130  is transferred through the collar  122  to the flats  126 . The torsional force is then retained by the flats  128  on the fluid manifold  14 , thereby maintaining a tight threaded connection between the threaded region  40  on the housing  32  and the internally-threaded inlet  42  on the dispenser body  12 .  
      Contact between the tip  140  of set screw  136  and the face  132  of nut  130  prevents relative rotation between the hydraulic fitting  28  and the collar  122  of lock member  120 . Because the contact between flats  126  and flats  128  prevents relative rotation between the fluid manifold  14  and the lock member  120 , as described above, it is apparent that the lock member  120  prevents relative rotation between the fluid manifold  14  and the hydraulic fitting  28 . Rotation of nut  130  in a clockwise direction, as viewed in  FIG. 5 , is prevented, which is the direction that otherwise loosens the housing  32  of hydraulic fitting  28 . Of course, opening  138  would be oriented differently to prohibit rotation in the clockwise direction, as viewed in  FIG. 5 , if the handedness of the threaded region  40  of housing  32  and the internally-threaded inlet  42  were changed.  
      In use and with reference to  FIGS. 1-5 , the lock member  120  is placed between the hydraulic fitting  28  and the neck  43  of the fluid manifold  14  with flats  126  on lock member  120  registered with flats  128  defined on the exterior of the neck  43 . The set screw  136  is withdrawn from contact with nut  130  during assembly. Using a tool engaged with the faces  132  of integral nut  130 , the hydraulic fitting  28  is rotated relative to the fluid manifold  14  to tighten the threaded engagement between the threaded region  40  and internally-threaded inlet  42 . When a targeted level of tightness is attained to provide a fluid-tight connection between the fluid manifold  14  and hydraulic fitting  28 , the set screw  136  is advanced until the tip  140  contacts one of the faces  132  of integral nut  130 . After liquid flow is established, the hydraulic fitting  28  directs liquid from the supply conduit  22  to the fluid manifold  14 .  
      As the operator moves about carrying the handheld dispenser  10 , the stem  48  and ball  46  of hydraulic fitting  28  rotate and tilt to accommodate changes in orientation of the dispenser body  12 . Torsional forces resulting from the operator&#39;s movement act in a direction that, if not counteracted and balanced, would otherwise cause the threaded region  40  on the housing  32  to rotate relative to the internally-threaded inlet  42  on the fluid manifold  14 . Advantageously, the lock member  120  operates to prevent relative rotation between the threaded region  40  on the housing  32  and the internally-threaded inlet  42  on the fluid manifold  14 . The torsional force transferred from the tip  140  of set screw  136  to the face  132  of nut  130  counteracts and balances the torsional force arising from the operator&#39;s movement such that a state of equilibrium is established. As shown in  FIG. 5 , the contact between the tip  140  of set screw  136  and one face  132  of nut  130  prevents rotation in a clockwise direction, which is a direction that would result in loosening of the hydraulic fitting  28  in response to torsional forces, were the lock member  120  not installed.  
      While the present invention has been illustrated by a description of various embodiments and while these embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicants&#39; general inventive concept. The scope of the invention itself should only be defined by the appended claims, wherein we claim: