Abstract:
In a preferred embodiment, an apparatus, including; telescoping inner and outer members; a release collar circumferentially encircling the outer member; at least one rotatably mounted pawl disposed in the outer member; the at least one rotatably mounted pawl being depressed into at least a first depression formed circumferentially in the inner member by the release collar; and the at least one rotatably mounted pawl being movable between unlocked and locked positions. A vibration damper for the hold open rod is also provided.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to hold open rods generally and, more particularly, but not by way of limitation, to a novel hold open rod that employs rotatably mounted pawls as locking members and a snubber. 
     2. Background Art 
     The following patents are known: 
     U.S. Pat. No. 3,367,689, issued Feb. 6, 1968, to McCarthy, and titled ADJUSTABLE STRUT, discloses a lengthwise adjustable strut that uses a dumbbell-shaped, loose member as a locking member. 
     U.S. Pat. No. 3,390,874, issued Jul. 2, 1968, to McCarthy, and titled TELESCOPIC STRUT, discloses a lengthwise adjustable strut that uses a cylindrical, loose member as a locking member. 
     U.S. Pat. No. 3,442,541, issued May 6, 1969, to Metz, and titled RELEASABLE FASTENER, discloses a lengthwise adjustable strut that uses a toothed, radially movable, loose member as a locking member. 
     U.S. Pat. No. 3,469,871, issued Sep. 30, 1969, to Betts, and titled RELEASABLE LOCKING DEVICE, discloses a lengthwise adjustable strut that uses one or more loose members as locking members. 
     U.S. Pat. No. 3,945,744, issued Mar. 23, 1976, to Metz and titled TELESCOPING STRUT CONSTRUCTION, discloses a lengthwise adjustable strut that uses one or more loose dogs as locking members. 
     U.S. Pat. No. 4,014,467, issued Mar. 29, 1977, to Ferguson, and titled DISHWASHER AND COUPLING, discloses a lengthwise adjustable coupling that uses one or more loose balls as coupling members. 
     U.S. Pat. No. 4,362,415, issued Dec. 7, 1982, to Metz et al., and titled EXTENSIBLE AND RETRACTABLE STRUT WITH SAFETY LATCH, discloses a lengthwise adjustable strut that uses a spring-loaded lever as a locking member. 
     U.S. Pat. No. 4,366,945, issued Jan. 4, 1983, to Blaüenstein, and titled HOSE COUPLING WITH DOUBLE LOCK, discloses a hose coupling that uses one or more loose balls as locking elements. 
     U.S. Pat. No. 4,453,449, issued Jun. 12, 1984, to Hollmann, and titled HOLDING APPARATUS, discloses a lengthwise adjustable holding apparatus that uses one or more loose balls as locking members. 
     U.S. Pat. No. 4,453,748, issued Jun. 12, 1984, to Ekman, and titled QUICK-COUPLING MEMBER, discloses a quick-coupling that uses one or more loose balls as locking members. 
     U.S. Pat. No. 4,546,956, issued Oct. 15, 1985, to Moberg, and titled COMPRESSED AIR COUPLING, discloses a compressed air coupling that uses one or more loose balls as locking members. 
     U.S. Pat. No. 4,682,795, issued Jul. 28, 1987, to Rabushka et al., and titled TENSION ACTUATED UNCOUPLER, discloses an uncoupler that uses one or more loose balls as locking members. 
     U.S. Pat. No. 4,960,344, issued Oct. 2, 1990, to Geisthoff et al., and titled LOCKING MECHANISM FOR FIXING AN OUTER PART ON AN INNER PART, discloses a lengthwise adjustable part that uses one or more loose balls as locking members. 
     U.S. Pat. No. 5,066,049, issued Nov. 19, 1991, to Staples, and titled LOCKOUT DEVICE FOR HOSE FITTING, discloses a hose fitting that uses one or more loose balls as locking members. 
     U.S. Pat. No. 5,265,970, issued Nov. 30, 1993, to LaBarre, and titled STRUT CONSTRUCTION, discloses a lengthwise adjustable strut that uses one or more loose balls as locking members. 
     U.S. Pat. No. 5,366,313, issued Nov. 22, 1994, to LaBarre, and titled STRUT CONSTRUCTION, discloses a lengthwise adjustable strut that uses one or more loose balls as locking members. 
     U.S. Pat. No. 5,579,875, issued Dec. 3, 1996, to Vargas et al., and titled SELF LOCKING STRUT, describes a lengthwise adjustable strut that uses spring-loaded pins as locking members. 
     U.S. Pat. No. 5,632,568, issued May 27, 1997, to Fechter, and titled AUTOMATIC UNCOCKING SHAFT SENSING COUPLER, discloses an uncocking shaft sensing coupler that uses one or more loose dogs or balls as locking members. 
     U.S. Pat. No. 5,779,385, issued Jul. 14, 1998, to Fechter, and titled AUTOMATIC UNCOCKING SHAFT SENSING COUPLER, discloses an uncocking shaft sensing coupler that uses one or more loose dogs or balls as locking members. 
     U.S. Pat. No. 5,950,997, issued Sep. 14, 1999, to Metz, and titled TELESCOPING STRUT CONSTRUCTION, discloses a lengthwise adjustable three-member strut that uses one or more loose locking dogs and a spring-loaded member as locking members. 
     In connection with most prior hold open rods or struts, there have existed significant problems involving inadvertent release under load. Specifically, with either compressive or tensile loads applied between the telescoping members of the prior art hold open rods or struts, there was a danger that the operator could accidentally slide the locking collar to a release position while the hold open rod or strut was still under load, possibly leading to a sudden collapse of the hold open rod or strut and an accompanying uncontrollable swing or fall of the component being held by virtue of its own weight. Such a condition was capable of causing serious injury or death to either the operator or other personnel in the area. 
     In the past, hold open rods or struts of the type noted have been used with aircraft cowlings, in order to retain the cowlings in an open position as during maintenance, and/or servicing of the aircraft engine. Depending on the size of the aircraft, such cowlings can weigh hundreds of pounds, and the potential of injury resulting from being struck by an inadvertently released cowling can be readily appreciated if one considers structures of such magnitude and size. 
     The more recently issued patents address this problem and require that a compressive load be removed, mechanically or manually, from the hold open rod or strut before the release collar can be moved and the hold open rod or strut thereafter collapsed. None of the cited patents require that the release mechanism be rotated a significant degree before the hold open rod can be collapsed. Such devices also still employ loose balls or dogs as the locking members and fail to address the following problems:
         In an intermediate position, the prior art hold open rods or struts do not offer locking under tensile loads.   Because the dogs are loosely retained, instances occur when the dogs actually roll over within their slots, causing jamming and non-lockup conditions. These instances can occur particularly under extreme vibration situations.   Due to a point contact of the dogs to the inner tube, there is less holding capacity than if a line contact were provided.   Because of the loose balls and dogs, there is more wear on the inner tube and release collar under vibration.   Because the loose balls and dogs can fall out, the devices offer less than failsafe designs.       

     None of the forgoing patents discloses the use of one or more rotatably mounted pawls as locking members. 
     Accordingly, it is a principal object of the present invention to provide a hold open rod that offers locking in the intermediate position under tensile loads. 
     It is a further object of the invention to provide such a hold open rod that prevents the locking members from rolling over within their slots. 
     It is an additional object of the invention to provide such a hold open rod that provides a line contact between the locking members thereof and the surface on which they ride, thus offering more holding capacity. 
     It is another object of the invention to provide such a hold open rod that provides locking members that are not loose. 
     A further object of the invention is to provide such a hold open rod in which the locking members thereof cannot fall out, thus providing a more failsafe design. 
     An additional object of the invention is to provide such a hold open rod with a vibration snubber as part of thereof. 
     Another object of the invention is to provide such a hold open rod that cannot be collapsed before rotating the release mechanism thereof a significant degree. 
     Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be elucidated in, or be apparent from, the following description and the accompanying drawing figures. 
     SUMMARY OF THE INVENTION 
     The present invention achieves the above objects, among others, by providing, in a preferred embodiment, an apparatus, comprising; telescoping inner and outer members; a release collar circumferentially encircling said outer member; at least one rotatably mounted pawl disposed in said outer member; and said at least one rotatably mounted pawl being depressed into at least a first depression formed circumferentially in said inner member by said release collar; and said at least one rotatably mounted pawl being movable between unlocked and locked positions. A vibration damper for said hold open rod is also provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       Understanding of the present invention and the various aspects thereof will be facilitated by reference to the accompanying drawing figures, provided for purposes of illustration only and not intended to define the scope of the invention, on which: 
         FIG. 1  is a side elevational view, in cross-section, of a hold open rod constructed according to one embodiment of the present invention in unlocked and stowed position. 
         FIG. 2  is a fragmentary, side elevational view, in cross-section, rotated 30 degrees from  FIG. 1 . 
         FIG. 3  is an end elevational view taken along line “ 3 - 3 ” of  FIG. 2 , but in the orientation shown on  FIG. 1 . 
         FIG. 4  is a side elevational view of a pawl according to the embodiment of  FIG. 1 . 
         FIGS. 5-17  are fragmentary side elevational views, illustrating the steps in locking and unlocking the release collar for compression and tension loads for the embodiment of  FIG. 1 . 
         FIG. 18  is a fragmentary side elevational view of a further embodiment of the present invention. 
         FIGS. 19-24  are fragmentary side elevational views, illustrating the steps in locking and unlocking the release collar for the embodiment of  FIG. 18 . 
         FIG. 25  is an end elevational view in cross-section of the follower ball of the embodiment of  FIG. 18  in a J-slot. 
         FIG. 26  is a top plan view of the lock body of the embodiment of  FIG. 18  showing, inter alia, the J-slot. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference should now be made to the drawing figures on which similar or identical elements are given consistent identifying numerals throughout the various figures thereof, and on which parenthetical references to figure numbers, when used, direct the reader to the view(s) on which the element(s) being described is (are) best seen, although the element(s) may be seen on other figures also. 
       FIG. 1  illustrates a hold open rod, constructed according to one embodiment of the present invention, and generally indicated by the reference numeral  30  in an unlocked and stowed position. Hold open rod  30  has conventional attachment points  40  at either end thereof Since attachment points are conventional, no further description thereof will be made. It will be understood that the terms “horizontal” and “vertical” when used herein refer to the positions of the elements being described shown on the drawing figures and other orientations of the elements may be provided as well. 
     Hold open rod  30  has elongated, horizontal, nested, cylindrical inner and outer members  50  and  52 , respectively, and slidably mounted on an extension  84  of the outer member is a horizontal cylindrical release collar  54 . Three pawls  60  (only one visible on  FIG. 1 ), spaced  120  degrees apart, are rotatably disposed in outer member  52 , each is disposed in a socket  62 , and each is disposed on a shaft  64 . Defined in release collar  54  are circumferentially extending unlocking and locking channels  70  and  72 , respectively, separated by a two-sided, vertical wall  74 . A vertical wall  80  defines the distal end of locking channel  72  and a horizontal wall  82  formed at the base of locking channel  72  rides on a portion of extension  84 . 
     As indicated above, hold open rod  30  is in its unlocked position, with pawl  60  protruding into unlocking channel  70  and resting on a wear sleeve  90  disposed on inner member  50 . A compression spring  100  is disposed between release collar  54  and extension  84 . First and second depressions  110  and  112  are circumferentially defined in inner member  50 . Each depression  110  and  112  has an inwardly sloping left wall, with an upper portion  120  and a lower portion  122  joined by a horizontal ledge  124 , and an inwardly sloping right wall  126 . Outer member  54  and extension  84  are joined by a horizontal threaded portion  130  and a vertical pin  132 . The purposes of pawls  60  and depressions  110  and  112  are discussed in detail infra. 
     In the position shown, an end of a horizontal pin  150  bears on an inner surface of connection  40  at the right end (as shown on  FIG. 1 ) of hold open rod  30 . A spring  160  is disposed between pin  150  and inner member  50 . Pin  150  is arranged such that it leaves contact with the inner surface of connection  40  as inner member  50  is partially withdrawn from outer member  52 . The purpose of spring-loaded pin  150  is to absorb vibrations when hold open rod  30  is in its stowed position. 
       FIG. 2  illustrates that the horizontal travel of release collar  54  is limited by a vertical pin  170  threadingly inserted through release collar  54  and extending into a slot formed in extension  84 . Alternatively, a vertical split ring collar  180  ( FIG. 1 ) may be provided to limit the degree of travel of release collar  54 . 
       FIG. 3  illustrates the location of pin  170  threadingly inserted through release collar  54  and extending into slot  172  and illustrates all three pawls  60  disposed on shafts  64  fixedly embedded in outer member  52 . 
       FIG. 4  illustrates pawl  60  in a horizontal position and shows that pawl terminates at its distal end in a vertical wall  200 . Depending from a distal end of pawl  60  is a pointed protuberance formed by sloped walls  210  and  212 , with wall  210  depending from vertical wall  200  and with wall  212  depending from a point intermediate vertical wall  200  and shaft  64 . An upwardly extending, truncated point is formed by wall  220  extending upwardly from vertical wall  200  and by wall  222  extending upwardly from a point intermediate the vertical wall and shaft  64 . A horizontal wall  230  extends from the base of wall  222  almost to shaft  64 . 
       FIG. 5  illustrates hold open rod  30  in its unlocked and stowed position ( FIG. 1 ). 
       FIG. 6  illustrates that inner member  50  has been pulled out of outer member  52  so that depression  110  underlies pawl  60  and release collar  54  has begun to be manually moved to the left on the figure. It will be assumed for illustration purposes that depression  110  will be used. Should hold open rod be extended fully, depression  112  would be used in the same manner as depression  110 . 
       FIG. 7  illustrates that release collar  54  has been mover further to the left, such that a corner of wall  74  has pushed pawl  60  downwardly so that wall  120  of depression  110  temporarily engages wall  222  of the pawl. 
       FIG. 8  illustrates inner member  50  has been pulled out further from outer member  52 . 
       FIG. 9  illustrates that release collar  54  has been moved further to the left, with wall  74  thus pressing pawl  60  further downwardly. 
       FIG. 10  illustrates that release collar  54  has been moved leftwardly to its locked position and the upper portion of pawl  60  has entered locking channel  72 . 
       FIG. 11  illustrates that a compressive load has been applied and has moved inner member  50  to the right on  FIG. 11 , thus raising pawl  60 . 
       FIG. 12  illustrates that the compression load has moved inner member  50  further to the right on  FIG. 11 , with horizontal wall  82  engaging horizontal wall  230  and wall  120  engaging wall  210 . In this position, hold open rod  30  is locked and release collar  54  cannot be moved until the compressive load is removed. 
       FIG. 13  illustrates that a tensile load has been applied to hold open rod  30  and has moved inner member  50  to the left on  FIG. 13 . Now, horizontal wall  82  is in engagement with horizontal wall  230  and wall  126  is in engagement with wall  212 . Again, in this position, hold open rod  30  is locked and release collar cannot be moved until the tensile load is removed. 
       FIG. 14  illustrates that the loads have been removed, release collar is beginning to be moved to the right and wall  74  begins to engage wall  220  of pawl  60 . 
       FIG. 15  illustrates that release collar  54  is moved further to the right and wall  74  pushes pawl  60  downwardly. 
       FIG. 16  illustrates that release collar  54  has been moved further to the right to the right and the top of pawl  60  begins to enter unlocked channel  70 . 
       FIG. 17  illustrates that inner member  50  has been moved to the right on the figure, thus lifting pawl  60 . 
     Finally, pawl  60  has been moved to its fully unlocked position shown on  FIG. 1 . 
       FIG. 18  illustrates a hold open rod, constructed according to a further embodiment of the present invention, and generally indicated by the reference numeral  300 . 
     Hold open rod  300  has elongated, horizontal, nested, cylindrical inner and outer members  310  and  312 , respectively, and slidably mounted on a lock body  320 , which is an extension of the outer member, is a horizontal cylindrical release collar  322 . Lock body  320  is attached to outer member  312  by means of threads  324  augmented by a pin  326 . Three pawls  330  (only one visible on  FIG. 1 ), spaced  60  degrees apart, are rotatably disposed in outer member  312 , each is disposed in a socket  332 , and each is disposed on a shaft  334  journaled in lock body  320 . Defined in release collar  322  is a circumferentially extending unlocking and locking channel  340  having a downwardly sloped surface  342  and a horizontal surface  344 . 
     Pawl  330  has a flat upper surface  350  and a pointed lower end  352 , the upper surface engaging downwardly sloped surface  342  and the pointed lower end being shaped complementary to the shape of depression  354  formed circumferentially around the outer periphery of inner tube  310 . Hold open rod  300  is shown on  FIG. 18  in its retracted and unlocked position. 
     Also shown on  FIG. 18  is a left hand wound combination torsion and compression spring  360  having its ends bent such that end  362  is inserted into a hole formed in release collar  322  and end  364  is inserted into a slot  366  formed in lock body  320  ( FIG. 26 ). It will be understood that, for clarity, torsion and compression spring  360  is shown as being in the same plane as pawl  330 , although such may not always be the case. In the position shown on  FIG. 18 , point  352  of pawl  330  rests on a wear plate  370 . A label  380  encircles an outer circumference of release collar  322  and a colored tape  390  is disposed in a groove encircling the inner periphery of lock body  320  to provide a visual indication that the release collar has been fully extended ( FIG. 21 ). 
     As illustrated on  FIG. 19 , hold open rod  300  is in an extended and unlocked position, with depression  354  under point  352  of pawl  330 . Hold open rod  300  has been moved to this position by extending inner tube  310  in the direction of the arrow shown on  FIG. 19 . 
     As illustrated on  FIG. 20 , hold open rod  300  is in an extended and still unlocked position, with spring  360  causing release collar to move in the direction shown by the arrow on  FIG. 19  and the release collar to begin to push down pawl  330 . To guide this movement, follower ball ( FIG. 25 ) is moving to the left in the longitudinal portion of J-slot  402  ( FIG. 26 ) formed in lock body  320 . 
     As illustrated on  FIG. 21 , hold open rod  300  is in its fully extended and locked position, with pawl  330  being pushed down into depression  354  by release collar  322  and with the upper surface  350  of the pawl engaging horizontal surface  344  of unlocking and locking channel  332 . Upon reaching this point, follower ball  400  ( FIG. 25 ), by virtue of torsion and compression spring  360 , has snapped into the transverse portion of J-slot  402  ( FIG. 26 ) and is held in the distal end of the transverse portion of the J-slot, thus preventing the collapse or extension of inner tube  310 . 
       FIG. 22  illustrates the beginning of the collapse of inner tube  310  into outer tube  312 . Here, release collar  322  has been manually rotated about thirty degrees, with the upper portion of the release collar being rotated toward the viewer. This moves follower ball  400  ( FIG. 25 ) out of the transverse portion of J-slot  402  ( FIG. 26 ) into the longitudinal portion of the J-slot. Further manual movement of release collar  322  causes follower ball  400  to move along the longitudinal portion of J-slot  402  to its distal end and pawl  330  to begin to be lifted up out of depression  354 . 
     As illustrated on  FIGS. 23 and 24  retraction of inner tube  310  into outer tube  312  in the direction of the arrows on  FIGS. 23 and 24  causes pawl  330  to be lifted out of depression  354  and further retraction of the inner tube causes hold open rod  300  to return to the position shown on  FIG. 18 . 
     As is illustrated on  FIG. 25 , the lower half of follower ball  400  rides in J-slot  402  ( FIG. 26 ) while the upper half of the follower ball rides in an opening formed in release collar  322 . Cap  410  is provided in release collar  322  to keep follower ball  400  from falling out. Also seen on  FIG. 25  are openings  322 ,  420 , and  422  for pawls  330 . 
     As noted above with respect to  FIG. 26 , shown thereon are slot  366  and J-slot  402 . Also seen on  FIG. 26  are openings  322  and  422  for pawls  330  and openings  430  for shafts  334 . 
     In the embodiments of the present invention described above, it will be recognized that individual elements and/or features thereof are not necessarily limited to a particular embodiment but, where applicable, are interchangeable and can be used in any selected embodiment even though such may not be specifically shown. 
     Spatially orienting terms such as “above”, “below”, “upper”, “lower”, “inner”, “outer”, “inwardly”, “outwardly”, “vertical”, “horizontal”, and the like, when used herein, refer to the positions of the respective elements shown on the accompanying drawing figures and the present invention is not necessarily limited to such positions. 
     It will thus be seen that the objects set forth above, among those elucidated in, or made apparent from, the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description or shown on the accompanying drawing figures shall be interpreted as illustrative only and not in a limiting sense. 
     It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention that, as a matter of language, might be said to fall therebetween.