Patent Abstract:
A bulk milk tank having a ladder that provides access to a raised platform in a lowered position and moves to a raised position to provide ample operating room around the tank outlet valve.

Full Description:
FIELD AND BACKGROUND OF THE INVENTION  
         [0001]    This invention relates generally to bulk milk tanks used in dairies, and more particularly to a bulk milk tank with an attached ladder that provides access to a raised platform for monitoring a milk gauge and obtaining milk samples. At least a portion of the ladder can be moved away from a tank outlet valve to provide easier access to the outlet valve.  
           [0002]    In dairies, milk is collected from a number of cows through a milking system and directed to a bulk milk tank for storage until the milk is transported off site. Bulk milk tanks are typically quite large cylindrical shapes with a longitudinal axis that is oriented horizontally. The ends of the tank are capped with convex ends to provide maximum storage capacity.  
           [0003]    Space being at a premium in many dairies, the tanks are designed to have all of their necessary functional elements accessible at one end of the tank. These elements include: an external milk gauge rod for determining the quantity of milk in the tank; an outlet valve for connecting to wash pumps, off-load pumps, or milk inlet lines; an access hatch on the top or end of the tank for obtaining milk samples; an elevated platform for operators to stand on while reading the milk gauge and taking milk samples; and a ladder for the operator to reach the platform.  
           [0004]    For safety reasons, the ladder is mounted on the tank to avoid the dangers associated with using a separate, and possibly unstable, ladder resting on the floor. Attached ladders provide operators with secure movement to and from the elevated platform.  
           [0005]    Unfortunately, ladders fixed to the end of a bulk milk tank consume a lot of space. Access to other elements, such as the outlet valve, can be inhibited by the ladder. Thus, what is needed is a bulk milk tank with a securely attached ladder that provides access to the elevated platform and ample clearance to use the outlet valve.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention is directed to a bulk milk tank having an attached ladder that moves between a lowered position to provide access to an elevated platform and a raised position to provide clearance for an outlet valve mounted near the tank bottom. This ladder provides benefits that are not known in any prior milk tank ladder.  
           [0007]    In its lowered position, the ladder provides access to the upper platform of the bulk milk tank. From the platform, milk samples and quantity readings can take place. After sampling, a portion of the ladder can be moved to a raised position to provide clearance and easy access to the milk outlet valve, which would otherwise be at least partially blocked by the ladder.  
           [0008]    Preferably, the ladder includes a lower section that slides relative to the upper section and is locked in the raised position by a pivoting latch.  
           [0009]    Risers to act as handrails can also be included, particularly near the top so that the user can move easily from the ladder to the tank platform and back again. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a perspective view of a bulk milk tank with a ladder in a lowered or climbing position in accordance with the present invention.  
         [0011]    [0011]FIG. 2 is a perspective view of the bulk milk tank of FIG. 1 with the ladder in a raised position.  
         [0012]    [0012]FIG. 3 is a front view of an upper section of a milk tank ladder in accordance with the present invention.  
         [0013]    [0013]FIG. 4 is a side view of the ladder upper section of FIG. 3.  
         [0014]    [0014]FIG. 5 is a front view of a ladder lower section in accordance with the present invention.  
         [0015]    [0015]FIG. 6 is a side elevation view of a lock to releasably maintain a lower ladder section in a raised position, in accordance with the present invention.  
         [0016]    [0016]FIG. 7 is a front elevation view of a pivoting lock latch used in the lock of FIG. 6. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]    Illustrated in FIG. 1 is a bulk milk tank and ladder system  20  in accordance with the present invention. The bulk milk tank and ladder system  20  includes a milk storage tank  22 , a series of supporting legs  24 , a ladder  26 , an outlet valve  28 , a milk gauge  30 , and a platform  32 .  
         [0018]    The milk tank  22  is preferably made of stainless steel and can hold from 600 gallons to 8000 gallons of milk from dairy animals being milked in a dairy. The tank  22  is generally cylindrical and has a substantially horizontal longitudinal axis extending from front  36  to back  38  of the tank  22 . The tank  22  is supported above a floor by legs  24 .  
         [0019]    The front  36  of the tank  22  is preferably substantially round in cross-section and is convex to increase tank storage capacity. The surface of the tank  22  is smooth and has no integral means for ascending to the access hatch  33 . Instead, a ladder  26  is joined to the front of the tank  22  by any suitable means including welds, bolts, or other type of fastener.  
         [0020]    The ladder  26  includes an upper section  40  and a lower section  42 . As seen in FIGS. 3 and 4, the upper ladder section  40  includes a pair of posts  46  that are oriented generally vertically and spaced apart from the upper portion of the tank front  36  to provide an easy handhold and clearance for the operator&#39;s feet while climbing. Joined to the bottom of the posts  46  are horizontal struts  48  that join the tank  22  to the posts  46  to maintain spacing.  
         [0021]    At the top of the posts  46  are risers  50  that spread outwardly from the posts  46  to provide handrails and ample working space for taking samples through the access hatch  33 . The risers  50  are joined to the topside  52  of the tank  22 . A ladder rung  54  spans the space between the posts  46 . The number of ladder rungs is not critical so long as all applicable safety codes and regulations are met. Preferably, the ladder rungs  54  are an inverted U-shape and have perforations for traction. (See: FIG. 6.)  
         [0022]    Also joined to the posts  46 , is a platform  32  on which an operator can stand while taking measurements from the milk gauge  30  or taking samples through the access hatch  33 . The platform  56  is joined to or is part of the ladder  26  in preferred embodiments, but a separate platform could be attached to the tank  22 . The platform  32  is preferable to a ladder rung because there is more space to support the operator and less chance for foot fatigue or slipping.  
         [0023]    The posts  46  also include four brackets  58  that serve to joint the upper ladder section  40  to the lower ladder section  42 . The brackets  58  are generally c-shaped and open inward toward the center of the ladder  26 . Inside of the c-shaped brackets are bushings  60  (See: FIG. 2), preferably plastic, that provide a close and low friction fit with the lower ladder section  42 .  
         [0024]    All of the components described above as being part of the upper ladder section  40  can be welded together to form a single weldment that itself is welded to the tank  22 . Otherwise, these same components can be joined to one another and the tank  22  in any suitable fashion.  
         [0025]    The lower ladder section  42  (FIG. 5) includes a pair of substantially vertical posts  66  that are sized to mate with the bushings  60  in the brackets  58  of the upper ladder section  40 . Spanning the distance between the posts  66  are rungs  68 , preferably six (6) in number and welded to the posts  66 . More or fewer rungs  68  can be used to compliment the size of the milk tank  22  on which the ladder  26  is mounted. On top of the posts  66  are caps  69  that are oversized relative to the cross-sectional area of the posts  66  so that they act as stops to prevent the lower ladder section  42  from sliding out of the brackets  58  of the upper ladder section  40 .  
         [0026]    With this construction, the ladder  26  can be used in a climbing position (FIG. 1) to access the platform  32  or in the raised position (FIG. 2) to have clearance for the outlet valve  28  by sliding the lower ladder section  42  relative to the upper ladder section  40 .  
         [0027]    A lock  70  is used to secure the lower ladder section  42  in its raised position (FIG. 2) while the outlet valve  28  is being accessed by an operator.  
         [0028]    A lock  70  for use with the present invention is illustrated in FIGS. 6 and 7. The lock  70  includes a pin  72  joined to or molded integrally with the lower ladder section  42 , and preferably to a rung  68  of the lower ladder section  42  via a bolt  73 . The lock  70  also includes a pivoting latch  74  that is joined to the upper ladder section  40  via a bolt  75 . The latch  74  engages the pin  72  to maintain the lower ladder section  42  safely and conveniently clear of the outlet valve  28  in the raised position.  
         [0029]    The pivoting latch  74  includes an upper handle portion  76  that can be manipulated from outside of the ladder post  46  to avoid a pinch point. On the opposite end is a hook  80  that is sized and shaped to mate with the pin  72 .  
         [0030]    On the underside of the hook  80  is a cam surface  82  that is engaged by the pin  72  when the lower ladder section  42  is being raised. The engagement of the pin  72  and the cam surface  82  pivots the latch  74  (counter-clockwise as viewed) enough to allow the pin  72  to be raised above the latch  74 . Either gravity, a spring, or manipulation by the user pivots the latch  74  (clockwise as viewed) to position the hook  80  under the pin  72 , so that slight downward movement of the lower ladder section  42  engages the pin  72  and the hook  80  to secure the lower ladder section  42  in a raised position.  
         [0031]    In a preferred embodiment, a tab  88  is formed on the hook  80  to add mass to the latch  74 . With the added mass, gravitational force is enough to rotate the latch  74  in a clockwise direction to a position that will support the pin  72 . In addition, a spring could be used to assist in the rotation of the latch  74 , but one is not necessary in the illustrated, preferred embodiment.  
         [0032]    A stud  86  engages the pin  72  in the event an operator raises the lower ladder section  42  too far. The stud  86  thereby limits how far the lower ladder section  42  can be raised.  
         [0033]    To lower the lower ladder section  42  to the climbing position, the operator slightly raises the lower ladder section  42  to clear the hook  80 . The operator then uses the upper handle portion  76  of the latch  74  to pivot the latch  74  counter-clockwise while simultaneously lowering the lower ladder section  42  toward the climbing position. Once the pin  72  is below the latch  74 , the latch  74  can be released.  
         [0034]    The lock  70  is illustrated as a latch and pin combination, but any type of mechanism that maintains the lower ladder section  42  in the raised position can be used.  
         [0035]    Aside from the plastic bushings  60 , all of the ladder elements are preferably made of stainless steel.  
         [0036]    The illustrated embodiment has a lower ladder section  42  that slides relative to the upper ladder section  40 , but it is possible to join the sections with hinges to pivot the lower section upward to provide access to the outlet valve. In all of these embodiments, the ladder has essentially two positions. First a climbing position to provide climbing access to the elevated platform. Second, a raised position where a section of the ladder is moved away from the outlet valve to permit necessary operations to take place on the valve. Nonetheless, the sliding embodiments require no clearance for the lower section to swing through, so the sliding version is more space economical.  
         [0037]    The foregoing detailed description is provided for clearness of understanding only and no unnecessary limitations therefrom should be read into the following claims.

Technology Classification (CPC): 8