Patent Publication Number: US-2005127695-A1

Title: Remote controlled load lifting hook and methods

Description:
CROSS REFERENCE TO RELATED APPLICATION  
      The present application claims the benefit of U.S. Provisional Application No. 60/528,759, filed on Dec. 10, 2003. The prior application is incorporated herein by this reference. 
    
    
     FIELD  
      This application relates to hooks used in lifting loads, and in particular, to remote controlled hooks used in lifting and maneuvering heavy loads.  
     BACKGROUND  
      Hooks used in lifting applications for general construction, fishing, logging, cargo handling, foundry work and other industries, are known. In some situations, there are advantages to providing a hook that can be controlled remotely, e.g., so as not to require an operator to directly handle the hook during one or more of the steps associated with a lifting operation. Examples of remote controlled hooks are described in commonly owned U.S. Pat. No. 4,095,833, U.S. Pat. No. 4,193,627, and U.S. Pat. No. 4,530,535, which are incorporated herein by this reference.  
      One common lifting application is cargo handling, which includes the lifting of cargo into and out of ships using a crane. Typically, hooks for lifting cargo are attached to strapping, webbing, wire and/or other type of slinging arrangement arranged around the cargo. The hooks may be used in groups that are suspended from a lifting frame and/or crane, usually by lifting chains. The hooks are engaged with the slings, usually by hand. Typically, the hooks are locked in a closed position, and the operator then engages the sling by passing it through to the throat of the hook, which may involve depressing a spring-loaded latch extending over the hook gap. It is also possible to lock the hook in place after the slings are received in the hook throat.  
      After the cargo is lifted and transported, it is desirable to release or unlock the hook remotely, preferably without requiring personnel to be in the direct area of the hooks to manually release them. Conventional cargo hooks are pneumatically controllable to be released or “unlocked” from the closed position to an open position in which the hook can freely pivot, and will usually be released from the sling without handling by an operator when the cable to which the hook is attached is raised. In some situations, conventional cargo hooks are configured to be unlocked for a predetermined time, and may automatically relock after that time. If the hooks relock while some or all of the slings are still in place within the throat of the hook, a second unlock cycle is necessary. If the crane operator remains unaware that the hooks have relocked and at least one of the slings is still attached, the current cargo may be jerked or moved unexpectedly when the operator attempts to move the hooks believed to be no longer underload.  
      Additional problems can arise if the lifting chain has too much or too little rotational freedom relative to the hook. If the hook is configured with a pneumatic line or other sources of power for the lock mechanism, care must be taken to protect the connections and ensure that the line is not entangled with the chain during operation. Also, hooks must be durable to withstand the rigors of the harsh handling environment, yet easy to service as necessary to avoid extensive downtime, e.g., during expensive procedures, such as a critical foundry operation or during unloading at a busy dock.  
     SUMMARY  
      To address these and other problems in conventional hooks, some embodiments of the new lifting hook design allow the degree to which the hook may rotate relative to the chain to be selected as desired. The hook may be configured to provide for free rotation of the hook relative to the chain, e.g., as provided by a swiveling section of the hook assembly, or the relative rotation may be confined to a predetermined range, e.g., up to 180 degrees as one example. As another alternative, the hook may be rotationally fixed relative to the chain as desired, e.g., by securing the swiveling section relative to the hook.  
      Embodiments of the new lifting hook design can include a locking mechanism that operates along an axis distinct from a main or lifting axis of the assembly. By disassociating the locking axis from the main axis (usually the axis of the body of the lifting hook), the locking components may be accessed more readily. In some conventional hooks, the locking axis is usually coaxial with the body axis, but this design can complicate disassembly of the device and lengthen the time required for service. In embodiments of the new lifting hook, the distinct locking axis may be parallel to but offset from the body axis (i.e., to the right, left, front or rear), or the distinct locking axis can be angled relative to the body axis. In specific implementations, the locking device may be angled at about 45 or about 90 degrees relative to the body axis, although any other angle that sufficiently spaces the locking components from the body axis can be used, including an angle from about 15 degrees to about 90 degrees.  
      Embodiments of the new lifting hook design can include a hook clearing member that functions to push off the sling or other object within the hook as the hook is pivoted to an open position, thus assisting in ensuring that the hooks do not remain connected to slings unintentionally while the hooks are subject to being relocked.  
      Embodiments of the new lifting hook design can include a deliberate locking feature requiring a positive manual effort, e.g., against a predetermined resistance, to close the hook before it can be relocked in an effort to reduce instances of unintentional relocking.  
      Embodiments of the new lifting hook design can include a retractor that functions to urge the hook toward an open position when the hook is free to pivot.  
      The disclosed apparatus and methods should not be construed as limiting in any way. Instead, the present disclosure is directed toward novel and nonobvious features and aspects of the various disclosed embodiments, alone and in various combinations and subcombinations with one another. The methods and apparatus are not limited to any specific aspect or feature or combinations thereof, nor do the disclosed methods and apparatus require that any one or more specific advantages be present or problems be solved. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       FIG. 1  is a sectioned elevation view of an embodiment of the remote controlled lifting hook in an unlocked condition with the hook pivoted, showing a body of the lifting hook, a locking device positioned approximately perpendicular to an axis of the body, a swivel cap coupled to the body, and an attached lifting chain.  
       FIG. 2  is an exploded perspective view of the lifting hook of  FIG. 1 .  
       FIG. 3  is an elevation view of another embodiment of a remote controlled lifting hook similar to  FIG. 1 , except the remote controlled locking device operates on an axis positioned at an acute angle relative to the body axis and the hook is shown in a locked position.  
       FIG. 4  is a perspective view of the swivel cap showing an end with a slot and a pin aperture, each of which is sized to receive a pin for selectively controlling the rotational range of the swivel cap relative to the body.  
       FIG. 5  is a perspective view of the lifting hook shown in  FIG. 3 , except with the hook clearing member removed to show the hook retracting spring.  
       FIG. 6  is a sectioned elevation view of another embodiment of a remote controlled lifting hook similar to  FIG. 1 , except the remote controlled locking device operates on an axis generally coaxial with the body axis.  
       FIG. 7  is a plan view of the lifting hook of  FIG. 6  taken at the line  7 - 7  in  FIG. 6 .  
       FIG. 8  is a sectioned elevation view showing part of another embodiment of a remote controlled lifting hook similar to  FIG. 6 , except incorporating a hook clearing member and a different hook return spring.  
       FIG. 9  is a sectioned elevation view similar to  FIG. 8 , except showing the hook in an unlocked and open position.  
       FIG. 10  is a partial perspective view showing a lower front side of the lifting hook of  FIG. 8 , except fitted with an alternative latch having a free end that is received in a recess of the hook tip.  
       FIG. 11  is a partial perspective view showing a lower rear side of the lifting hook of  FIG. 8 , except the hook is fitted with a different latch. 
    
    
     DETAILED DESCRIPTION  
      Referring to  FIGS. 1 and 2 , a first embodiment of a lifting hook  10  includes an elongate body  12  and a swivel cap  14  coupled to the body for selective rotation relative to the body, as is described in detail below. The swivel cap  14  is fitted with a transverse chain retaining pin  16  for coupling a lifting chain  18  (shown partially in the figures) to the lifting hook. Referring to  FIG. 2 , there is a transverse retaining pin  20  that interfaces with a groove  21  on the pin  16  to retain it in place within the swivel cap  14 . The swivel cap  14  can have internal link receiving portions, such as a first link receiving portion  17   a  and a second link receiving portion  17   b , which are shaped to define cavities that receive and support the first and second links, respectively, of the chain  18 .  
      The swivel cap  14  is coupled to the body  12  by an attachment member  22  extending upwardly through the body  12  and into the swivel cap  14 . The attachment member  22  may form a threaded connection or another type of connection. In the illustrated embodiment, the attachment member  22  is a socket head cap screw that also has a groove for receiving a transverse retaining pin  24  extending through the swivel cap  14 .  
      A hook  30  is pivotably coupled to the body  12  by a pivot pin  28 . The pivot pin  28  may be secured in position by a retaining pin  33  that engages a groove  35  on the pivot pin  28 .  
      In  FIG. 1 , the hook  30  is shown in a pivoted position in which a hook axis A defined by the hook  30  intersects a body axis B defined by the body. The hook axis A and the body axis B are generally defined at an approximately central location of the hook and the body, respectively. When the hook is rotated from the pivoted or open position shown in  FIG. 1  to the closed position (see, e.g.,  FIG. 3 ), the hook axis A and the body axis B are generally parallel, and in the illustrated embodiment, are generally coaxial.  
      The hook  30  can be selectively secured or locked in the closed position with a lock mechanism. In the illustrated embodiments, a lock member, such as a lock pin  34 , is selectively controlled to extend and engage a recess  36  formed in the hook  30 , thereby preventing the hook from pivoting about the pivot pin  28 . In the embodiment of  FIGS. 1 and 2 , a locking axis C is approximately perpendicular to the body axis B, and is also approximately perpendicular to the hook axis A when the hook  30  is in the closed position. In other embodiments, as described below, the locking axis C is configured differently.  
      The lock pin  34  may be a rod of a piston (as shown in the illustrated embodiments), the plunger of a solenoid, or other type of controllably movable pawl or member. The lock pin  34  or locking member may be a single component that is directly coupled to the hook, or it may be a multiple component assembly in which the controllably movable member moves another member that contacts and secures the hook.  
      As shown in  FIG. 1 , the lock pin  34  in the illustrated embodiments is slidably received in a bore  48  of the body  12 . The lock pin  34  has an attached piston  46  that is slidably received in a bore  50 . A spring or other biasing device  52  is positioned to urge the lock pin  34  towards its locked position. In  FIG. 2 , the spring  52  bears against the piston  46 .  
      The lock pin  34 /piston  46  and spring  52  are secured in place by a cap  58  and a snap ring  60 . The lock pin  34  and the piston  46  may be fitted with respective seals  54  and  56  as shown. The removable snap ring  60  and cap  58  allow easy access for servicing and/or changing the seals  54 ,  56  and the lock pin  34 . There may be inspection openings  88  formed in the hook  30  and the body  12 , which, when aligned as shown, e.g., in  FIG. 3 , permit an operator to visually confirm that the lock pin  34  is fully extended and in the locked position.  
      A latch  40  for the hook  30  is coupled to the body  12 . In the illustrated embodiments, the latch  40  is pivotably coupled to the body  12  by a pivot pin  41  and is biased to the closed position as shown in  FIG. 2 , e.g., by a spring  42 . When the hook  30  is in the locked position, the latch  40  functions to prevent inadvertent release of a sling or slings within the throat of the hook.  
      As described, the hook  30  can be remotely controlled. For example, the hook  30  may be selectively controlled to withdraw the lock pin  34  from the recess  36 , thereby allowing the hook  30  to pivot from the lock position to the pivoted position, e.g., to release the load. In the illustrated embodiments, the hook  30  is pneumatically controlled using compressed air or other compressed gas, such as nitrogen. In other implementations, a hydraulic system could be used. It would also be possible to use an electrically actuated solenoid, servo motor or other similar device.  
      In the embodiment shown in  FIGS. 1 and 2 , there is a pneumatic line  62  for providing a supply of pressurized gas which is connected to a fitting  64  attached to the body  12 . A passageway  66  leads from the fitting  64  to one side of the piston  46 . When desired, pressure can be supplied to this side of the piston  46  to move it against the force of the spring  52  and cause the lock pin to be withdrawn.  
      The body  12  can be structured to provide protection for the fluid or power connection. For example, as shown in  FIG. 1 , the body can have flanges  89  that extend above and to the side of the fitting  64  to provide protection for the connection between the pneumatic line  62  and the fitting  64  during use and handling.  
     Hook Clearing  
      In some embodiments, the lifting hook  10  may be fitted with a hook clearing member  84  that assists in ensuring that any sling within the hook is completely removed from the hook when the hook is pivoted from the lock position to the open position. In  FIG. 1 , the hook clearing member  84  is shown attached to the body  12  and having two opposing sides that straddle the hook  30 . When the hook  30  is fully pivoted to the open position as shown in  FIG. 2 , the throat of the hook, i.e., the portion of the hook that bears the load, moves leftward beyond the stationary sides of the hook clearing member  84 .  
      Although shown as a separate piece in the illustrated embodiments, it would of course be possible for the hook clearing member  84  to be formed as one piece with the body. Alternatively, other hook clearing structures that incorporate a moving element to more positively assist in disengaging the sling from the hook could be used.  
      The hook clearing member  84  can also have a stop  85  positioned to contact the hook  30  and serve to prevent rotation of the hook beyond a predetermined “fully open” position. In  FIG. 1 , the stop  85  is shown extending within a recess  86  and bearing against an inner surface of the hook  30  to prevent further rotation.  
       FIGS. 8-11  show a hook clearing member  84 ′, which is another variation. As best seen in  FIG. 9 , the hook clearing member  84 ′ in this example does not project beyond the tip of the hook  30  when the hook is pivoted to the fully open position, but the hook throat does pivot beyond the member  84 ′. As also best shown in  FIG. 9 , there is a stop  85 ′, which is an edge of the rear connecting portion of the hook clearing member  84 ′. The rear surface of the hook  30  bears against the stop  84 ′ when the hook is in the fully open position.  
     Hook Retracting  
      The hook may be fitted with a retracting member that urges the hook  30  toward the open position when the hook is free to pivot, e.g., when the lock pin  34  has been withdrawn. As best shown in  FIG. 2 , the retractor can be a spring  74  with two generally symmetrical side portions and a connecting middle portion between the side portions. As assembled in  FIG. 3 , each side portion of the spring  74  has an end fixed to the body and extending laterally along an inner surface of the body and around the openings for the pivot pin  28 , angling upward and across a back side of the hook  30  to join the other side portion. The ends of the spring  74  can be bent to engage the inspection holes  88  in the body as shown.  FIG. 5  is another view of a lifting hook without the hook clearing member  84  that shows the spring  74 .  FIG. 7  shows a different view of the spring  74  in relation to the body  12  and the hook  30 .  
       FIGS. 8, 9  and  11  show a different hook retracting configuration. In  FIGS. 8, 9  and  11 , there is a coil spring  74 ′ with a first moving end attached to the hook  30  and a second stationary end attached to a stationary portion of the lifting hook. In the specific example of  FIGS. 8, 9  and  11 , the spring is attached to a bent tab  75  of the hook clearing member  84 ′.  
     Deliberate Engagement Prior to Locking  
      The lifting hook may have a deliberate engagement feature to prevent inadvertent locking of the hook  30  by the lock pin  34 . Depending upon the position of the lifting hook at rest, e.g., if it was lying with its rear surface in contact with the floor or the top surface of the cargo, the hook  30  could be in a closed position and subject to being unintentionally relocked. Unintentional relocking could occur if the controlled unlock time for the lock pin expires, i.e., the piston  46  is allowed to close, while the hook is in the closed position. Unintentional relocking may be undesirable if there are still slings within the hook  30 . A deliberate engagement feature such as a spring  72  can be positioned on the body  12  to bias the hook  30  slightly away from the closed position. Thus, the spring  72  requires the operator to manually apply a predetermined positive force to pivot the hook  30  to the fully closed position, and thus helps to ensure that the hook  30  is only fully closed when it is intended to be relocked.  
      The spring  72  may be a flat leaf spring held in place on the body  12  with a set screw as shown in  FIG. 1  (see also  FIGS. 2, 8  and  9 ). Alternatively, there may a coil spring  72 ′ as shown in  FIGS. 6 and 7 . Although not specifically shown in the drawings, a member made from a resilient material, such as rubber or the like, could be configured to serve as the deliberate engagement feature. Other biasing arrangements would also be suitable, as would be known to one or ordinary skill in the art.  
      With the spring  72  or  72 ′, an attempt to relock the hook  30  will not be successful unless the biasing force of the spring is overcome, which would ordinarily require an operator&#39;s manual manipulation of the hook  30 .  
     Selective Rotation  
      As indicated, the swivel cap  14  can be configured (1) to rotate freely, i.e., over at least 360 degrees relative to the body  12 , (2) to rotate over a desired angular range (e.g., over about 180 degrees) relative to the body  12 , or (3) to be fixed and not rotate relative to the body  12 . If free rotation is desired, the body  12  and the swivel cap  14  are assembled together without the pin  76 . If rotation over an angular range is desired, the pin  76  is inserted into the body pin aperture  80 , and the swivel cap  14  is assembled together with the body  12  such that the pin  76  is in a slot  78  of the desired angular range.  FIG. 4  is a perspective view of the swivel cap  14  showing an end with the slot  78 . The pin  76  can be positioned in the slot  78  when the swivel cap  14  and the body  12  are assembled together to restrict rotation of the swivel cap  14  to the angular range of the slot  78 , i.e., about 180 degrees in this example. If no relative rotation is desired, the pin  76  is inserted into the body pin aperture  80 , and the other end of the pin is inserted into the cap pin aperture  82  when the swivel cap  14  is assembled together with the body  12 .  
      The selective rotation functionality can be made available for use while the lifting hook is assembled. For example, a longer pin  76  can be used in conjunction with a cap pin aperture  80  that extends through the swivel cap  14  cap to provide the user with the ability to select the desired relative rotation. If limited rotation is desired, the protruding pin is depressed to engage the body pin aperture  82  (no rotation) or the slot  78  (rotation only a limited angular range) in the body  12 . The pin can be secured against unintentional movement, e.g., by use of a detent or similar retainer.  
     Coaxial Locking Axis  
       FIGS. 6 and 7  show another embodiment of the lifting hook. This embodiment is similar to the other embodiments described above, except (1) the locking axis C is approximately coaxial with the body axis B, and (2) the swivel cap  14  is coupled to the body  12  by a collar  23  instead of the bolt  22 . As described above, the deliberate engagement feature is the coil spring  72 ′ instead of the flat leaf spring  72 .  
       FIGS. 8-11  show another embodiment with a vertical locking axis. In the embodiments with a vertical locking axis, as best shown in  FIGS. 6, 8  and  9 , the lifting hook can include a removable cartridge  37  in which is formed the cylinder  48  for the lock pin  34 . The cartridge  37  can be secured with a retaining pin  38  that extends into the body. The removable cartridge construction may be advantageous in some embodiments to allow installation and removal of the lock pin  34 /piston  46 .  
     Locking Axis Variations  
      As indicated above, the lifting hook can be configured such that the locking axis is not coaxial with the axis of the body. In some embodiments, the locking axis and the axis of the body intersect to form an acute angle. In still other embodiments, as in the embodiment of  FIGS. 1 and 2  and the embodiment of  FIGS. 3 and 5  the locking axis and the axis of the body intersect to form a 90 degree angle and a 45 degree angle, respectively. Implementing a locking axis that is not coaxial with the axis of the body provides certain advantages with respect to ease of disassembly of the lock pin  34  and related components. For example, it may be possible to leave the lifting hook connected to the lifting chain  18  while servicing one of the seals. Although not shown, the locking axis can be offset from but still parallel to the body axis to achieve some of the same advantages.  
      For other implementations, such as is shown in the embodiment of  FIGS. 6 and 7 , the lifting hook may have a locking axis generally coaxial with the body axis and still realize other advantages as described.  
     Latch Variations  
      As best shown in  FIGS. 2 and 11 , the latch  40  may be sized slightly wider than the tip of the hook  30  such that the latch  40  protrudes beyond the sides of the hook. For some applications, it may be desirable to incorporate a latch  40 ′ that is generally narrower than the hook  30 . As best shown in  FIG. 10 , the latch  40 ′ is pivotably connected to the body  12  and spring biased similar to the latch  40 , but the hook  30  is shaped with a recess to receive the free end of the latch  40 ′ and allow it to pivot.  
     General Construction  
      In general, it is desirable to construct the lifting hook such that the outermost surfaces tend to slide away from objects with which they make inadvertent contact during use, instead of catching on or snagging such objects. In use, the lifting hooks are generally suspended in a generally upright position, i.e., with the body axis B generally vertical. Therefore, viewing the lifting hook in elevation, the outermost surfaces that might come into inadvertent contact with, e.g., the side of a cargo ship, are generally gently sloping or curved, and the use of planar surfaces or projections (e.g., the heads of fasteners), which might be prone to interfere with and “grab” objects, is minimized. Thus, the overall construction of the lifting hooks in the described embodiments is referred to as “non-snagging.” 
      The various components of the lifting hook  10  may be made of any suitable material. In most implementations, the major components are made of a steel. Other materials, such as fiberglass, plastics, composites, ceramics, etc., are also suitable, depending upon the particular environmental conditions and operating requirements. In some implementations, certain components are made of a material resistant to environmental effects, e.g., stainless steel or variations of bronze may be used for one or more components where corrosion is a concern.  
      Although the invention has been disclosed in this patent application by reference to the details of some preferred embodiments, it is to be understood that this disclosure is intended in an illustrative rather than in a limiting sense, as it is contemplated that modifications will readily occur to those skilled in the art within the spirit of the invention.