Abstract:
A dairy milker unit detacher having a milker unit support arm that resists damage and breakage by incorporating a breakaway mechanism that disengages and then automatically or easily returns the support arm to a functional arrangement when a dairy animal or other force engages the support arm.

Description:
FIELD AND BACKGROUND OF THE INVENTION 
     The present invention relates to milker unit detachers for use in dairy harvesting facilities, and in particular to a milker unit support arm device that resists accidental damage from dairy animals. 
     In dairy harvesting facilities, milker units are attached to dairy animals to automatically milk the animals. Milk is collected in the milker units and fed through milk tubes that are connected to a central dairy pipeline system. At the end of a milking operation on each animal, the milker units are detached and moved away from the dairy animal using a milker unit detacher. 
     In some dairy harvesting facilities such as rotary milking parlors, milking stalls are confined spaces that require the milker unit to be withdrawn from under an animal and moved to a storage position that enables animals to enter and egress its milking stall without damaging the milker units and the milker unit detachers. To do this, the milker unit is supported by a movable detacher support arm that swings and/or pivots from a milking position to a storage position. 
     Despite operation and movement of the support arm, dairy animals often come into contact with the support arm during entry to and egress from the milking stall, and during a milking operation. Such contact can damage the milker unit support arm, interfere with dairy operations, and require time consuming and expensive maintenance. 
     To minimize damage to milker unit detachers, spring-loaded assemblies have been used to accommodate a limited amount of impact or force from dairy animals. Known spring loaded detachers accommodate movement in one direction. While useful, these prior spring assemblies did not accommodate support arm movement in all directions, and were relatively difficult to reset. 
     Thus, there is needed a milker unit detacher with a support arm that supports and moves a milker unit from a milking position to a storage position and is resistant to damage from dairy animals. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a milker unit detacher arm that supports a milker unit when in a milking position, when moving between a milking position and a storage position, and is resistant to damage from contact by dairy animals or other forces. 
     A dairy milker unit support arm in accordance with the present invention includes a controlled breakaway assembly that enables a support arm tube or bar to flex in all directions when engaged by a dairy animal and then be automatically or easily returned to a standard support position. 
     The support arm can include first arm segment with a bearing surface formed or attached to its proximate end that bears on a bearing surface of a second arm segment. A tension element such as a spring can be used to hold the support arm in place until a predetermined load to the support arm is exceeded. When such a load is applied, the tension element is further tensioned and the bearing surface can become disengaged to harmlessly absorb the dairy animals force. This action prevents the support arm from being bent or broke, and yet when the load is removed, the support arm bearing surfaces can be repositioned with the aid of the tension member and the undamaged support arm is ready for another use. 
     The tension member can be adjustable so that the tension is set to keep the support arm supportive during milking and detaching operations, but low enough to protect the support arm from substantial damage when engaged by a dairy animal or any other force, such as operators, cleaning equipment or any other person or device in the dairy facility. The tension member can be a spring, resilient member, or any element that can be tensioned to hold the first and second arm segments in bearing to contact during normal use. 
     The support arm can be substantially horizontal in the milking position and substantially vertical in a storage position. These orientations are typical in rotary milking parlors, for example. It may be desirable to use the support arm to support other milking components, such as hoses for milk and pulsation, and to properly align a milking unit under or near an animal during attachment of the milker unit and the milking operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective view of a milker unit detacher with a support arm in accordance with the present invention, in a milking position; 
         FIG. 2  is a front perspective view of a milker unit detacher with the support arm in a breakaway position; 
         FIG. 3  is a side view of a breakaway device for a milker unit support arm in accordance with the present invention; 
         FIG. 4  is an exploded perspective view of a breakaway device for a milker unit support arm in accordance with the present invention; 
         FIG. 5  is an end view of the breakaway device for a milker unit support arm in accordance with the present invention; 
         FIG. 6  is a cross-section of the breakaway device for a milker unit support arm taken along line  6 - 6  of  FIG. 5 ; 
         FIG. 7  is a cross-section of the breakaway device for a milker unit support arm taken along line  7 - 7  of  FIG. 5 ; 
         FIG. 8  is a perspective view of a bearing surface of the present invention; 
         FIG. 9  is an end view of the bearing surface of  FIG. 8 ; 
         FIG. 10  is a cross-section of the bearing surface taken along line  10 - 10  of  FIG. 9 ; 
         FIG. 11  is a cross-section of the bearing surface taken along line  11 - 11  of  FIG. 9 ; 
         FIG. 12  is a side view of the bearing surface of  FIG. 8 ; 
         FIG. 13  is a breakaway cable in accordance with the present invention; 
         FIG. 14  is a partial cross-section of the cable of  FIG. 13 ; 
         FIG. 15  is a perspective view of a tensioning member in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following detailed description of the drawings, the same reference numeral will be used to designate the same or similar elements in each of the figures. 
       FIG. 1  illustrates a milker unit detacher  20  joined to a cabinet  22  that preferably forms part of a milking stall in a dairy harvesting facility. The cabinet  22  can be any appropriate size, shape or construction to accommodate a milker unit detacher operating mechanism, such as disclosed in U.S. Pat. Nos. 6,814,027 and 6,990,923, and PCT/US09/03536, incorporated herein by reference. The cabinet  22  can be an enclosed cabinet, as illustrated, or it can be an open cabinet or have an open frame construction. 
     The operating mechanism can be any suitable mechanism and preferably includes a pivoting hub  30  joined to the cabinet  22  and to a support arm  32 . The hub  30  preferably pivots about an axis to move the support arm  32  between a milking position (as illustrated in  FIG. 1 ) to a storage position. Preferably, the milking position is a substantially horizontal orientation of the milker unit support arm  32  and the storage position is a substantially vertical orientation, but other orientations are possible and within the scope of the present invention. 
     As illustrated in  FIG. 1 , the milking position of the milker unit support arm  32  blocks an open portion of the milking stall  24  through which a dairy animal enters and egresses. In this position, the support arm  32  is vulnerable to bending and breaking if a dairy animal moves during milking or moves too quickly when exiting the milking stall  24 . 
     Dairy animals can be unpredictable and move suddenly in any direction. Thus, the support arm  32  must absorb a force applied by the dairy animal from any direction. To reduce or prevent damage to the support arm  32 , more robust components can be used. Nonetheless, the size and weight of a dairy animal can damage even robust milker detacher components. The present invention includes a breakaway assembly  38  that reduces support arm damage. 
     The breakaway assembly  38  is preferably joined to or is integral with the milker unit detacher support arm  32  at a location closer to the cabinet  26  than a distal end  44  of the detacher arm  32 . As best seen in  FIGS. 3 through 15 , the breakaway assembly  38  preferably includes a first arm segment  46 , a second arm segment  48 , a cable  50 , and a tensioning mechanism  54 . The first arm segment  46  and the second arm segment  48  can be integral with or attached to portions of the support arm  32  or they can be installed at the proximate end of the support arm  32 . In the illustrated example, the first arm segment  46  is joined to a support arm  32  using any suitable type of connector or connection including screws, bolts, welding, swaging and others. As described below, the first arm segment  46  is closer to the cabinet  22  than the second arm segment  48 , but they could be reversed, as well. 
     Preferably, the first arm segment  46  and the second arm segment  48  are identical in shape and construction, but this is not absolutely necessary within the scope of the invention. Each arm segment  46 ,  48  preferably defines a chamber  58  through which the cable  50  extends. Each arm segment  46 ,  48  also includes a bearing surface  60 . 
     In addition, each arm segment  46 ,  48  preferably includes a tubular portion  61  and an enlarged portion  64 . The tubular portion  61  can include a clearance hole  66  through which a connector can join the tubular portion  61  to the tensioning mechanism  54 . The enlarged portion  64  is tapered to act as a ramp to aid in returning the breakaway assembly  38  to its normal position. 
     The bearing surface  60  on each arm segment  46 ,  48  can be flat, concave, convex or any other suitable shape or size. In a preferred embodiment, the bearing surface  60  includes a peripheral flat surface  62  that is transverse or about 90° relative to a longitudinal axis of the arm segment  46 ,  48 . Interior to the flat surface  62  is a ramped surface  64  disposed at about 45° relative to a longitudinal axis of the arm segment  46 ,  48 . The ramped bearing surface  64  extends longitudinally outwardly and inwardly from the flat surface  62 , and has an interior shoulder  66  and an exterior shoulder  68  disposed at about 15° relative to the longitudinal axis of the arm segment  46 ,  48 . The interior shoulder  66  on one arm segment engages the exterior shoulder  68  on a mating arm segment. Preferably, the first and second arm segments  46 ,  48  are made of nylon 6, black, but other materials can be used as well. 
     The first arm segment  46  fits against the second arm segment  48  in a releasable arrangement. Tension on the cable  50  (as described below) holds the first arm segment  46  and the second arm segment  48  together under most circumstances. Nonetheless, the cable  50  is flexible enough that a force from a dairy animal, for example, can cause the first arm segment  46  and the second arm segment to disengage as depicted in  FIG. 2 . The tension in the cable  50  automatically reassembles the first and second arm segments  46 ,  48  or, at worst, an operator may have to assist in bringing the two parts back together. The cable  50  can be any flexible element, but is preferably a 7×19 cable that is made of stainless steel. 
     To apply and maintain tension in the breakaway assembly  38 , the cable  50  and the tensioning mechanism  54  interact to set a desired tension. In the illustrated embodiment, the cable  50  includes a first end portion  70  having to set a desired tension a first bearing member  72  attached thereto using any suitable means, including swaging. The first bearing member  72  has a broadened portion  76  to define a shoulder  78  that bears on an internal shoulder  80  of the first arm segment  46 . (See  FIGS. 6 and 7 ). 
     The cable  50  also preferably includes a second end portion  84  onto which a stud  86  is joined by any suitable means including swaging. The stud  86  can include wrench flats  88  for turning or holding with a wrench or preferably a slot, through which a screw driver or other device is inserted for holding the piece securely, and threads  90  that are used to connect and adjust the cable  50  to the tensioning mechanism  54 . The tensioning mechanism  54  could be at either end of the breakaway assembly  38 , but for space considerations, it is preferred to be joined to the second arm segment  48  or at least at the distal end of the breakaway assembly  38 . 
     In the illustrated embodiment, the second end portion  84  of the cable  50  extends through a tensioning element  52 , and is joined to the tensioning mechanism  54 . The tensioning element  52  is preferably a compression spring, but it can be a resilient member or component that tensions the cable  50 . Also preferably, the tensioning member  52  is a Danly Diemax XL Spring, Part #9-1206-36, Sprg.0.750X1.50-Yellow-X-Heavy Rectangular Wire, Hole Diameter: ¾ in. (20 mm), Free Length: 1.50 in (38 mm), Spring Constant: 111.00 lbs/0.10 in (194.0N/mm) available from distributors throughout the United States, including Airgas, 1007 Monitor Street, P.O. Box 3119, La Crosse, Wis. 54601. 
     The tensioning mechanism  54  further includes a second bearing member  94 , a washer  98 , a first nut  102 , and a second nut  104 . Tightening the first nut  102  applies a force to the washer  98  to compress the tensioning element  52 . This pretensions the cable  50  and applies a bearing force that maintains the bearing surfaces  60  of each arm segment  46 ,  48  in bearing contact. The second nut  104  is a jam nut that maintains the desired position of the first nut  102 , and preferably the threads  90  and/or the threads of the nuts  102 ,  104  are treated to prevent the threads from locking (“freezing”). 
     The second bearing element  94  transfers force from the tensioning element  52  to the second arm segment  48 , as illustrated. The second bearing element  94  preferably includes a connector hole  96  that aligns with the alignment hole  66  on the second arm segment  48 . 
     In use, the support arm  32  operates as any other milker unit support arm. The combination of size of the bearing surfaces  60  and tension in the cable  50  maintains the first arm segment  46  in a coaxial arrangement with the second arm segment  48  until the applied force exceeds a predetermined force, the cable  50  bends, the tensioning element  52  may compress slightly, and the first arm segment  46  and the second arm segment  48  buckle about their respective bearing surfaces  60  to the position illustrated in  FIG. 2 . When the force is removed, the spring  52  expands to tension the cable  50  and realign the first arm segment  46  and the second arm segment  48 , either automatically with no assistance from an operator, or easily with some assistance by an operator. 
     The foregoing detailed description of the invention is for clearness of understanding only and no unnecessary limitations therefrom should be read into the following claims.