Abstract:
Flat or flat-faced detents are insertable in corresponding flat sided apertures in container support posts to provide increased surface contact area and better load distribution.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of Invention  
         [0002]     This invention relates to locking or latching—by so-called ‘detents’ of telescopic posts for freight containers.  
         [0003]     Terminology  
       Detent  
       [0004]     The term ‘detent’ embraces diverse forms, but a feature is one or more (load)—e.g., multiple discrete or single continuous—contact bearing surfaces.  
         [0005]     The nature, shape, contour or profile of an individual bearing surface admits of considerable variation and may be continuous or discontinuous.  
         [0006]     A detent is typically part of a male-female locating or fastening contrivance.  
         [0007]     A common container support post is configured as a telescopic strut, of mutually inter-fitting post elements, of generally rectangular cross-section, with a locking pin detent operative therebetween.  
         [0008]     Pins are inserted in mutually aligned aperture creating through-holes in juxtaposed post elements.  
         [0009]     This secures relative position and transfers (axial) stacking and suspension loads.  
       Index Positions  
       [0010]     Apertures are traditionally incrementally spaced for relative post adjustment in prescribed multiples.  
         [0011]     Aperture alignment defines index positions in relative post element disposition.  
         [0012]     Detent location and retention is by contact friction under transferred load.  
         [0013]     That said, optional locking elements may be fitted.  
         [0014]     Generally, detents sit—and are movable across or transversely of—post and relative post mobility axes.  
         [0000]     Disposition &amp; Orientation  
         [0015]     Some aspects of the invention are concerned with aperture and detent disposition and orientation.  
         [0016]     Temporary removal of a detent from a post movement path is required to allow relative post positional adjustment.  
         [0017]     Detent re-instatement preserves a given relative post positioning—for load transfer therebetween.  
       Racking  
       [0018]     In addition to compression (stacking) and tension (lift) loads imposed longitudinally along a post or strut axis, transverse ‘racking’ loads across the post axis can arise upon handling and interaction with other stacked containers in transit.  
       Transverse vs Longitudinal  
       [0019]     Racking can arise across transversely (i.e., from side-to-side) or longitudinally (i.e., from end-to-end) of a container deck platform.  
         [0020]     Transverse racking is generally more acute than longitudinal racking, particularly when multiple clustered corner end posts are employed, as with dual span (say 40 ft and 45 ft standard) platforms.  
       Shear  
       [0021]     Such racking loads put a post in shear—to withstand which local post cross-section and location of detent apertures are important considerations.  
       Tension &amp; Compression Faces  
       [0022]     More specifically, for a rectangular post cross-section, opposed faces in the plane of racking are in shear and bounding opposed faces are respectively in compression and tension upon post bending tendency.  
       Tolerance &amp; Lozenging  
       [0023]     Tolerance between slidably inter-fitting posts and between post location apertures and detents allows racking loads to create lozenging of container profile.  
         [0024]     A snug interfit between location aperture and detent is thus desirable—consistent with ease of insertion and removal, along with considerations of corrosion and wear discussed later.  
         [0025]     Detent apertures with local removal of wall material mean local post section weakening.  
         [0026]     Thus detent aperture profile and disposition must take account of post loading—particularly in shear.  
       Round Detent Pin  
       [0027]     Traditionally round detent pins are used, for ease and low cost of production from standard round section bar stock.  
         [0028]     A conventional (nominally) round(ed) pin detent form, generally of uniform or symmetrical circular section, is readily adopted from standard bar stock sizes or sections.  
         [0029]     Alternatively, bespoke detent diameters are readily machined (e.g. turned down on a lathe) from bar stock.  
         [0030]     Similarly, a round aperture is readily drilled.  
         [0031]     Other profiles, such those with flat facets as envisaged in the present invention, require special machining—an on-cost consideration, but one offset by certain operational benefits later described.  
       Localized Contact, Limited Bearing Surface, Localized Wear &amp; Corrosion  
       [0032]     For necessary working clearance, round aperture and pin sections afford limited bearing contact.  
         [0033]     Generally, such contact is made at one or other side—according to whether bearing (downward) stacking or (upward) lifting loads.  
       Load Distribution—Wear Susceptibility  
       [0034]     A limited contact area offers minimal load distribution and so is susceptible to surface sliding contact friction wear, upon repeated pin insertion and removal and vibration in transit under load.  
         [0035]     Repeated and reverse (un)loading create an elongated or oval wear form -with even greater slack or play admitted between unloaded post elements.  
         [0036]     Limited contact means susceptibility to localized wear, corrosion at contact surfaces and seizure.  
       Corrosion  
       [0037]     Moreover, surfaces in even limited contact, upon exposure to atmospheric moisture and even salt spray, such as during a sea voyage, over a prolonged period, are prone to corrosion and seizure in situ.  
         [0038]     Severe shock impact loads are needed to loosen and free pins corroded in situ—and which may damage, distort and buckle a pin profile, impeding ongoing (re-)insertion and removal.  
         [0039]     That in itself creates wear and an irregular scuffed surface profile, with even greater vulnerability to corrosion—and so the undesirable cycle repeats.  
         [0040]     2. Related Art  
       Adjustable Post Span  
       [0041]     Variable container support post height or span is known.  
         [0042]     Such variability can be achieved by adjusting, re-locating, or even substituting altogether, certain key structural elements, such as elongate (support) struts, posts or ties, which define or reflect the overall container dimensional span, in particular height or depth in relation to a base platform.  
       Container Posts  
       [0043]     Co-pending patent applications such as GB0029438.9, Australian No 47705/00, German No 10082697.0, U.S. Ser. No. 09/743777, and U.S. Ser. No. 10/726763 (based upon PCT WO98/09889—itself reflecting GB97/02319) envisage deck support post adjustability, in the context of deck position and orientation variability—for multiple independent deck module stacking.  
       Detent  
       [0044]     These applications also introduce flat-faced detents in general terms—but not in the developed forms now envisaged and set out herein.  
         [0045]     Similarly, GB1505657 envisages containers with telescopic legs, swung from stowage within a container profile, to a laterally-outboard stance, at which they are extended to lift and support a container clear of a carrier vehicle chassis.  
       Adjustable Posts  
       [0046]     A diverse mix of adjustable post structures has been proposed for varied applications, for example:  
         [0047]     U.S. Pat. No. 4,492,170—vertically adjustable table post with u-shaped bent metal locking plate;  
         [0048]     U.S. Pat. No. 3,850,395—instrument support structure with telescopic post element and pivoting base legs lockable by extendable struts per fluid actuators;  
         [0049]     U.S. Pat. No. 6,554,235—telescopic support post with external longitudinal grooves for clamping engagement with accessory support brackets;  
         [0050]     U.S. Pat. No. 4,896,992—adjustable mounting frame of profiled frame sections and connectors, with square detent protrusions for frame engagement;  
         [0051]     GB2274773—telescopic table leg whose upper portion is secured to table top and received within hollow lower leg portion, with friction-fit plastic bushings and optional spring-loaded detent;  
         [0052]     U.S. Pat. No. 5,307,598—post with adjustable mounting for post inclination relative to a ground stake;  
         [0053]     U.S. Pat. No. 5,110,076—adjustable multiple support stand for medical fluids, with support poles individually adjustable to a desired height by spring-loaded trigger assemblies with locking pins.  
         [0054]     However, none of this art recognizes or refines detent configuration issues.  
       OBJECTS AND SUMMARY OF THE INVENTION  
       [0055]     It is in general an object of the invention to provide a new and improved detent for locking telescopic posts as used, for example, in freight containers.  
         [0056]     Another object of the invention is to provide a detent of the above character which overcomes the limitations and disadvantages of the prior art.  
         [0057]     These and other objects are achieved in accordance with the invention by providing a detent assembly having two relatively movable elements with openings which are aligned with each other when the elements are in a predetermined position, and a detent body inserted into the aligned openings to hold the two elements in the predetermined position with a (continuous or discontinuous) flat face bearing surface of the body in load supporting engagement with one of the two elements over substantially the entire surface area of a flat abutment face along one edge of the opening in the element.  
         [0058]     One aspect of the invention provides—in the context of a support post, such as upon a container platform base—a detent, or retention element, for (index) location of movable posts or struts, with a flat-faced profile portion, upon one or more abutment faces, for load bearing and/or sharing contact with corresponding post reception apertures.  
       Flat-Faced Bearing Surface(s)  
       [0059]     A prime bearing surface form according to the invention is a flat, or flat-faced, profile.  
         [0060]     Flat applies to both localized detent surface profile and corresponding aperture profile.  
         [0061]     A single continuous flat surface represents a simple detent form, but variants are envisaged.  
         [0062]     Thus, segmented multiple juxtaposed flat surface portions or ‘lands’, separated by intervening transition profiles, such as grooves or recesses, could be employed.  
         [0063]     Flats are contiguous in the sense that material continues in between, but in a recessed profile.  
         [0064]     A serrated profile is a particular such discontinuous profile, with individual spaced flat lands or faces lying generally parallel to one another.  
         [0065]     Overall ‘flat’ surface area is greater than over other (say pronounced curvature) profiles or forms—albeit, ‘nearly’ flat or shallow curvatures are not precluded.  
         [0066]     Thus flat-faced, mutually interfitting male-female bearing surfaces characterizes detent action according to the invention.  
       Container Format  
       [0067]     A container format with telescopic posts and detents may be open or closed, box, platform or lattice.  
         [0068]     Posts can be hinged for collapse fold upon a platform base—in a so-called ‘flat-rack’ configuration.  
       Detent Path  
       [0069]     Operationally, a detent movement path generally has component of movement transverse (e.g., orthogonal) to a post longitudinal axis.  
         [0070]     This does not preclude ‘diagonal’ (i.e., a combination of longitudinal and transverse) disposition according to some aspects of the invention.  
         [0071]     Post span reduction by telescopic fore-shortening and detent relocation can allow fold upon a base with mutually juxtaposed posts.  
       Post Face Interaction  
       [0072]     A detent interacts with a selected aperture set in an upright support post face.  
         [0073]     For racking suppression, detent apertures are set in post faces aligned transversely of a deck platform.  
         [0074]     Thus detent insertion and withdrawal is longitudinally of the platform.  
         [0075]     Other detent considerations according to various aspects of the invention include: 
        a plate bearing surface area as a ‘large’ proportion of overall post cross-section;     post elements of mutually inter-fitting profile—e.g. telescopic;     ‘slack’ fit—clearance opposite to loaded contact face;     oblique (for example, ‘diagonal’) movement—gravity (self location;     wedge action—in which an oblique/sloping/tapered face draws together corresponding post faces into abutment;     a segmented face or stepped face;     detent retention.        
 
       Detent Retention  
       [0083]     A detent security retention, entrainment or entrapment can be contrived with, say, a latch or lock, such as a removable cross-pin, itself captured by a fastener, such as a spring clip.  
         [0084]     Thus, upon withdrawal from aligned detent apertures in juxtaposed inner and outer post faces, a detent can remain partially (say nose) inserted in, or held captive alongside, an outer post aperture.  
         [0085]     That is, a single outer post detent aperture is aligned with a selected one of a succession of inner post apertures to achieve a set relative axial positioning of inner and outer posts.  
       Detent Carrier  
       [0086]     A detent can be fitted upon a support or ‘carrier’, with action and/or configuration characteristics including: 
        free (floating);     entrained (e.g. restraint chain), held captive; or     supported over range of (dis)engagement. 
 
 Detent Movement Path 
       
 
         [0090]     Generally, a detent guide(way) and/or carrier determines detent movement path or traverse and complements contact surface profile.  
         [0000]     Arcuate  
         [0091]     So, say, an arcuate movement path could be reflected in an arcuate detent bearing surface.  
         [0092]     Common respective arc centers could be employed to minimize surface interaction—that is for smooth uninterrupted detent entry and withdrawal in relation to a correspondingly profiled detent aperture.  
       Extremities  
       [0093]     Limit extremities of detent movement may also be defined, if not the path between.  
       Alignment  
       [0094]     Detent alignment with a detent aperture at, or close to, an extremity of movement may also be ensured.  
       Arcuate Detent Path—Profile  
       [0095]     Thus, say, a swing arm detent carrier could suspend a detent about an upper pivot—allowing detent movement through an arc about the pivot.  
         [0096]     A shallow (arcuate) face curvature detent profile could complement an arcuate carrier path.  
       Arc Tangent  
       [0097]     Alternatively, a detent (bearing surface - taper) contact path could represent a tangent to a carrier movement arc, at a fully inserted or installed detent position within a mounting aperture.  
       Complex Pivot  
       [0098]     A bespoke complex pivot, such as an elongate pivot pin hole or double pivot could be employed, to admit more linear detent movement.  
       Operational Considerations  
       [0099]     Further detent operational considerations include: 
        ease of insertion &amp; removal;     inhibition of corrosion risk;     preservation of clearance/tolerant fit—notwithstanding load bearing face contact, so contact can be broken, by movement of surfaces away from one another.        
 
       Mechanical (Dis)Advantage/Velocity Ratio  
       [0103]     Some mechanical (dis-)advantage, leverage or (velocity ratio) gearing could be incorporated in detent carrier—and/or by interaction with a detent or between detent and detent aperture.  
       Detent Re-Orientation  
       [0104]     Detent re-orientation may be effected between removal and re-insertion, say to present a different depth span.  
       Detent Cam Action  
       [0105]     Similarly, detent re-orientation (say rotation) could drive detent aperture re-disposition—say in the manner of a lifting cam.  
         [0106]     Such a rotational cam action could also effectively lock a detent within a detent aperture—or at least take up mutual interfit tolerance or slack.  
         [0107]     Desirably, a detent is configured for manual insertion and/or removal.  
       Power-Assisted Detent Action  
       [0108]     That said, powered or power-assisted detent action might be contemplated—say with an external torque wrench or impact hammer.  
         [0109]     Nevertheless, overall, minimal detent and detent carrier complexity for purpose are desirable.  
       Interfit  
       [0110]     In order to minimize relative movement and attendant noise (rattle) and profile lozenging or trapezoidal racking, a close interfit between pin and location aperture or hole is desirable.  
         [0111]     Such racking attends static and dynamic post loading—with an axial stacking or lifting component and transverse shear or bending component.  
         [0112]     In relation to a container (deck) platform, or rectangular cross-sectional planform, transverse (cross-deck) racking is more severe than longitudinal (along-deck) racking, which can be damped by deck coupling to multiple spaced support posts.  
       Supplementary Statement(s) of Invention  
       [0113]     According to one aspect of the invention, a detent, or retention element, for location between relatively movable posts, has a flat faced bearing contact profile, upon one or more abutment faces, for load bearing/sharing contact with corresponding post apertures.  
       Taper—Wedge  
       [0114]     A tapered detent profile may be adopted, for progressive wedge locking abutment action with a corresponding post aperture or hole profile.  
         [0115]     In practice, a taper can represent or be expressed by diverse configurations, including: 
        an inclination, say acute angle, between a bearing or contact surface and a direction of mobility or freedom of movement; and/or     a progressively changing spacing or depth between opposed bearing surfaces, with either or both inclined to a movement direction.        
 
         [0118]     Thus, say, a slim flat plate, of tapered planform and of either even or tapered depth, may be employed.  
         [0119]     Taper is not restricted to flat surfaces, rather the relative spacing of curved surfaces can reduce.  
       Adjustable Post  
       [0120]     According to another aspect of the invention an adjustable span container support post, with relatively movable post elements is fitted with intervening ‘flat’ or flat-faced detents, such as flat plates, to preserve relative disposition of post elements.  
         [0121]     Insertion of a detent effectively preserves or retains relative post element disposition.  
         [0122]     A flat detent face can extend over a substantial proportion of an overall post cross-section—or at least significantly greater than a conventional round pin.  
         [0123]     Detent apertures may also be tapered—say of progressively varying depth in a direction of detent relative movement—in order to complement detent profile taper. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0124]     There now follows a description of some particular embodiments of the invention, by way of example only, with reference to the accompanying diagrammatic and schematic drawings, in which:  
         [0125]      FIG. 1  shows a perspective view of a telescopic support post, with juxtaposed flat-face detent pin;  
         [0126]      FIGS. 2A and 2B  show vertical sectional views of the support post of  FIG. 1 , with detent pin inserted, and attendant local contact enlargement, under stacking and lifting;  
         [0127]     More specifically:  
         [0128]      FIG. 2A  shows detent pin insertion to transfer downward stacking post loading;  
         [0129]      FIG. 2A A shows a local enlarged contact surface detail of  FIG. 2A ;  
         [0130]      FIG. 2B  shows a detent pin inserted to transfer upward stacking post loading;  
         [0131]      FIG. 2B B shows a local enlarged contact surface detail of  FIG. 2B ;  
         [0132]      FIG. 3  shows a perspective view of a telescopic support post, such as of  FIG. 1 , but with a tapered plate detent pin and complementary waisted profile post reception apertures;  
         [0133]      FIGS. 4A, 4B  and  4 C show various transverse and vertical sections through the support post of  FIG. 3 , with detent pin disposition and local contact enlargement; more specifically:  
         [0134]      FIG. 4A  shows tapered (plan) detent pin introduction to mutually aligned reception apertures of corresponding tapered profile in inner and outer support post elements;  
         [0135]      FIG. 4B  shows a follow-on stage to  FIG. 4A , with full tapered detent pin insertion, and (optional) end retention;  
         [0136]      FIG. 4B B shows a local enlarged contact surface detail of  FIG. 4B ;  
         [0137]      FIG. 4C  shows a vertical section of a support post under downward stacking loading;  
         [0138]      FIG. 4C C shows a local enlarged contact surface detail of  FIG. 4C ;  
         [0139]      FIG. 5  shows a perspective view of a telescopic support post, such as of  FIGS. 1 and 3 , but with a variant detent pin with head location profile;  
         [0140]      FIGS. 6A and 6B  show vertical sections through the post of  FIG. 5  with local contact enlargement; more specifically:  
         [0141]      FIG. 6A  shows initial detent pin insertion; and  
         [0142]      FIG. 6B  shows full detent pin insertion upon downward stacking loading;  
         [0143]      FIG. 6B B shows local enlarged contact surface detail of the lower detent portion of  FIG. 6B ;  
         [0144]      FIG. 6B BB shows local enlarged contact surface detail of the upper detent portion of  FIG. 6B ;  
         [0145]      FIG. 7A  shows a vertical post section with an enlarged head inclined detent;  FIGS. 7B through 7L  show variant detent pin and attendant location aperture configurations for the arrangement of  FIG. 7A —with only local detail depicted for simplicity; more specifically:  
         [0146]      FIG. 7A  shows a vertical section through a telescopic support post with an enlarged head detent pin, under downward stacking loading;  
         [0147]      FIG. 7B  shows a vertical section through a telescopic support post with serrated detent pin profile, under downward stacking loading;  
         [0148]      FIG. 7C  shows a vertical section through a telescopic support post with stepped detent pin profile, under downward stacking loading;  
         [0149]      FIG. 7D  shows a vertical section through a telescopic support post with waisted detent pin profile, under downward stacking loading;  
         [0150]      FIG. 7E  shows a vertical section through a telescopic support post with dual coupled detent stems, under downward stacking loading;  
         [0151]      FIG. 7F  shows a vertical section through a telescopic support post with concave waisted detent pin profile, under downward stacking loading;  
         [0152]      FIG. 7G  shows a vertical section through a telescopic support post with cruciform detent pin profile, under downward stacking loading;  
         [0153]      FIG. 7H  shows a vertical section through a telescopic support post with bowed detent pin profile, under downward stacking loading;  
         [0154]      FIG. 7J  shows a vertical section through a telescopic support post with constrained detent pin profile, under downward stacking loading;  
         [0155]      FIG. 7K  shows a vertical section through a telescopic support post with sagging detent pin profile, under downward stacking loading;  
         [0156]      FIG. 7L  shows a vertical section through a telescopic support post with serrated detent pin upper profile and slidable insertion/removal platform, under downward stacking loading;  
         [0157]      FIGS. 8A through 8R  show diverse stand-alone detent profiles; more specifically:  
         [0158]      FIG. 8A  shows a single-sided plate taper form;  
         [0159]      FIG. 8B  shows a truncated pyramidal stub form;  
         [0160]      FIG. 8C  shows a double-sided, vertical plate taper form;  
         [0161]      FIG. 8D  shows a double-sided planform plate taper form;  
         [0162]      FIG. 8E  shows an angled plate form;  
         [0163]      FIG. 8F  shows a discrete angled twin plate form;  
         [0164]      FIG. 8G  shows an inverted ‘U’ or ‘C’ section plate form;  
         [0165]      FIG. 8H  shows a concave strip form;  
         [0166]      FIG. 8J  shows a stacked discrete plate form;  
         [0167]      FIG. 8K  shows a transverse paired discrete plate form;  
         [0168]      FIG. 8L  shows a multiple array or cluster of juxtaposed vertical taper plate forms;  
         [0169]      FIG. 8M  shows a bifurcated plate form;  
         [0170]      FIG. 8N  shows off-set detent apertures in a support post;  
         [0171]      FIG. 8O  shows a (mortice and tenon) slidable inter-fitting detent form;  
         [0172]      FIG. 8P  shows a vertical stack of double-sided planform tapered detents;  
         [0173]      FIG. 8Q  shows a rectangular profiled inter-connecting detent form;  
         [0174]      FIG. 8R  shows a dovetail inter-connecting detent form;  
         [0175]      FIGS. 9A through 9C  show a prior art round detent pin; more specifically,  
         [0176]      FIG. 9A  shows a conventional round pin in a round hole;  
         [0177]      FIG. 9B  shows an enlarged view of the surface contact area of  FIG. 9A ;  
         [0178]      FIG. 9C  shows a close-fitting pin in hole with intervening corrosion.  
         [0179]      FIGS. 10A and 10B  reflect a practical flat -rack container construction with paired extensible, cross-braced, end posts with flat-face detents according to the invention; more specifically:  
         [0180]      FIG. 10A  shows an end elevation with (corner) end post (inner post element) extension beyond cross-braced (outer) bottom post elements; and  
         [0181]      FIG. 10B  shows a side elevation with suspended upper deck and detent retention;  
         [0182]      FIGS. 11A and 11C  show flat face detent and detent aperture profiling, along with supplementary view aperture for inner and outer post element aperture alignment preparatory to detent insertion, for the container of  FIGS. 10A and 10B ; more specifically:  
         [0183]      FIG. 11A  shows local interaction of a flat-faced detent with detent apertures in upper extensible (inner) and (base) outer post elements;  
         [0184]      FIG. 11B  shows an enlargement detail of  FIG. 11A ;  
         [0185]      FIG. 11C  shows variant detent profile options. 
     
    
     DETAILED DESCRIPTION  
       [0186]     As reflected in  FIG. 1 , a detent for a telescopically adjustable container post has a flat face—as does a corresponding location aperture in a post face.  
         [0187]     Detent load transfer bearing action and contact faces are reflected in FIGS.  2 A through  2 BB.  
         [0188]     Beyond merely flat, diverse detent forms are explored to meet particular operational considerations in  FIGS. 3 through 8 R.  
       Common Feature  
       [0189]     This diversity should not distract from a fundamental common feature—that is flat or flatness in detent and aperture profile.  
       Detent Profile  
       [0190]     A detent is configured as a short stem or stub element, with at least one local flat-faced load surface contact area on one side—and desirably upon opposite sides, to accommodate reverse loading.  
       Squat  
       [0191]     Detent length or span is relatively ‘modest’—and detent breadth is relatively ‘generous’.  
         [0192]     Such a ‘stubby’ or ‘squat’ profile is desirable in order to take stacking or lifting loads, without undue bending or distortion.  
         [0193]     Detent depth is ‘generous’, with similar rationale.  
         [0194]     Thus in  FIGS. 1 and 2 A/ 2 B, a detent  20  is configured as a flat, even depth, plate, with opposite (horizontal) upper and lower bearing surfaces  21 A,  21 B between parallel upright side surfaces  22 .  
         [0195]     Detent  20  locates in both: 
        a complementary profile aperture or slot  14  in a lower (outer) post element  12  of a telescopic (container) support post  10 ; and     a corresponding aligned aperture  15  in an upper (inner) post element  11 .        
 
         [0198]     In practice, detent apertures are desirably disposed in post side faces aligned transversely of the container platform—to counter attendant greater susceptibility to racking.  
         [0199]     Longitudinal racking is inhibited by the paired end posts as evident in  FIG. 10B .  
       Rectangular—Tapered—Trapezoidal  
       [0200]     Detent cross-section is desirably generally rectangular in (horizontal) plan, but trapezoidal and tapered forms can be contemplated.  
         [0201]     Similarly, a rectangular (vertical) cross-section is desirable, but again trapezoidal and tapered forms can be contemplated.  
         [0202]      FIG. 3  shows a tapered planform detent  30  of even depth, again with upright intervening sides  32  between opposite (upper and lower) flat faces  31 , and with depending retention stub  38 .  
       Differential Location Apertures  
       [0203]     With such a detent profile, differential span ‘entry’ and ‘exit’ (detent location) apertures are desirable.  
         [0204]      FIG. 4A  shows juxtaposed wide, but progressively reduced, span entry apertures  44 ,  46  and exit apertures  43 ,  45  in outer and inner post sections  12 ,  11  respectively.  
         [0205]      FIG. 4B  shows taper wedge detent  30  fully occupying aligned aperture pairs,  43 ,  45  and  44 ,  46 .  
         [0206]     A detent nose apex  33  emerges from the opposite side of posts  11 , 12  to that of entry.  
         [0207]     This exposes a capture aperture  34  for a lock pin  35 , itself with a bored stem to receive a locking clip  37 .  
         [0208]     Lock pin  35  is fully inserted until a head  36  sits upon detent face  31 —whereupon stem bore emerges from the detent  30  to receive clip  37 .  
         [0209]     Detent  30  profile and corresponding apertures  43 ,  44 ,  45 ,  46  are configured for wedge locking abutment action upon detent  30  insertion.  
         [0210]     Thus, inner post  11  exit aperture  45 , is restricted to minimal width to allow detent nose  33 , to emerge from outer post  12  to receive lock pin  35 .  
         [0211]     In practice, this means through-passage of detent  30  is restricted within inner post  11  when detent nose  33  has just passed through exit aperture  45 .  
         [0212]     Thus, further insertion of detent  30 , through entry apertures  44  and  46 , forces inner post  11  to move with detent  30  until it abuts with outer post  12  at the exit side.  
         [0213]     Lock pin  35 , and in particular head  36 , is configured to retain nose  33  in a position which maintains the abutment of inner and outer posts  11 ,  12 .  
         [0214]     Lateral working clearance, tolerance or slack  39  (shown exaggerated for clarity) between posts  11 ,  12  appears to the trailing side of wedge  30 .  
         [0215]     According to transverse or horizontal taper profile, clearance between the other sides could be shared evenly between posts  11 ,  12 —or offset to one side.  
         [0216]     With a vertical, upright or longitudinal (in relation to post axis) detent taper, such as in  FIG. 8A , vertical clearances between detent and reception aperture could be (re-)distributed, or taken up altogether.  
         [0217]      FIG. 4B B enlargement detail of  FIG. 4B  shows snug interfit of detent  30  and exit apertures  43 ,  45 .  
         [0218]      FIG. 4C C enlargement detail of  FIG. 4C  shows vertically offset clearances between detent  30  and entry apertures  44 ,  46 .  
         [0219]     This reflects imposition of stacking load through a capture fitting  13  upon upper inner post  11 , and transfer as shear across detent  30  to outer post  12 .  
       Truncated Pyramid  
       [0220]     A combination of horizontal and vertical taper, or truncated (absent or minimal apex) pyramidal form, would provide a dual wedge locating action between telescopic post sections.  
       Detent Profile Variants  
       [0221]      FIGS. 7A through 7L  and  8 A through  8 R explore variant detent profile—and are generally self-explanatory, so will not be described in detail.  
         [0222]     Similar considerations apply to interaction between detent and reception apertures in support posts.  
       Inclined Detent  
       [0223]      FIG. 5  depicts an inclined detent  50  orientation and disposition in relation to post axis.  
         [0224]     In this case the detent  50  is otherwise generally a flat plate with opposed upper and lower bearing surfaces  51  and orthogonal side edges  52 .  
         [0225]     A somewhat enlarged locating head  54  prefaced by a narrower neck recess or slot  53  terminates the outboard end of the plate stem, for location in a complementary ‘T’ profile slot  64  in posts  11 ,  12 .  
         [0226]      FIG. 6B  shows secure detent  50  location, with head  54  somewhat overlapping the outer post  12 .  
         [0227]      FIG. 6B B local enlargement detail of  FIG. 6B  reflects relative inner and outer post  11 ,  12  displacement upon downward stacking load.  
         [0228]     Similarly, with  FIG. 6B BB local enlargement detail of  FIG. 6B , but for the upper detent portion.  
       Split Wedge  
       [0229]     An expandible, e.g. bifurcated or split, expandible wedge configuration (not shown) could take-up slack, working clearance or tolerance between detent and aperture.  
         [0230]     This would also promote relative lateral movement between telescopic post sections—again to take up operating clearance or tolerance therebetween.  
         [0231]     Similarly, inclined, waisted or chamfered longitudinal side edge profiles  22 ,  32 ,  52  can be employed—effectively giving additional bearing surface.  
       Re-Entrant  
       [0232]     A multiple re-entrant—say stepped or serrated dovetail—vertical sectional profile could embody vertically and horizontally staggered, mutually overlapping, bearing surfaces.  
         [0233]     Again, such a configuration would increase the overall (collective) bearing surface.  
         [0234]     Tapered planforms and edge profiles could be adopted for such re-entrant forms.  
       Multi-Element Detent  
       [0235]     Rather than a unitary structure, a detent could comprise co-operatively disposed—possibly mutually inter-fitting—subsidiary detent elements.  
         [0236]     Thus, an individual detent could be substituted by multiple discrete detent elements—set in a cluster or group for individual or collective movement.  
         [0237]     Such detent split or fragmentation allows greater subtlety of control upon insertion or removal.  
       Phased Location  
       [0238]     Thus, detent portions could undergo relatively phased movement—i.e. location or insertion and removal—in relation to post apertures.  
       Longitudinal Split  
       [0239]     A longitudinally split or fragmented detent could employ successive intercoupled detent portions, say of progressively lesser width and/or depth in the direction of driving insertion.  
         [0240]     In such a split detent a wider portion could locate initially within aligned aperture portions to one side of respective telescopic post sections.  
         [0241]     This would be followed by a narrower detent portion engaging corresponding aperture portions at the opposite side.  
       Lateral Split  
       [0242]     Similar considerations could apply to a lateral split detent—say with detent portions juxtaposed side by side of similar or different operating length or span.  
       Stacked Detent  
       [0243]     Detents could be juxtaposed (mutually aligned or staggered), say, face-to-face in a vertical or horizontal stack.  
         [0244]     Successive detents could have differential span, such as progressively greater span.  
         [0245]     Thus (relative) displacement of each detent in turn effects incremental collective overall displacement.  
         [0246]     Relatively slim individual detent layers or wafers could contribute to a substantial overall stack depth.  
       Single—Multiple Contact Surfaces  
       [0247]     Single or multiple contact surfaces may be employed at one or more sides.  
       Single—Multiple—Offset—Inclined Contact Planes  
       [0248]     A simple format is a single contact (flat) plane such as of  FIG. 1 , but multiple offset and/or relatively inclined planes may be employed.  
         [0249]     A flat plane is convenient, but complex surface profiles are feasible.  
         [0250]     These could be contrived to inhibit inadvertent detent dislodgement, even without a retention fastener.  
         [0251]     Authorised detent removal would require knowledge of concealed geometry and prescribed movement sequence to extricate—and even then possibly only when posts are unloaded.  
         [0252]     Thus, say, curved, and multiple contiguous segmented, say serrated, profiles may be adopted.  
         [0253]     In this context, curve means shallow curved—as opposed to the markedly round or abrupt transitional forms of conventional round pin detents/apertures.  
         [0254]     An objective remains to increase overall load bearing contact surface area.  
         [0255]     A curve could provide a somewhat greater surface area in a given span.  
         [0256]     A complementary aperture profile is employed for that portion of a detent in local contact—to allow insertion, removal and for load transfer.  
       Combination  
       [0257]     A combination of round pin and flat plate detent could be employed.  
       Differential  
       [0258]     Differential aperture and detent sections may be adopted to create some relative positional interaction, upon insertion and withdrawal.  
       Symmetrical/Asymmetrical  
       [0259]     Either or both symmetrical and asymmetrical detent forms, locally or overall, can be employed.  
       Abrupt Transitional Profile  
       [0260]     An abrupt transitional detent profile can help resist inadvertent dislodgement, without unduly obstructing insertion when unloaded.  
       Multiple  
       [0261]     Multiple, co-operatively disposed, mutually entrained, detents could be configured for simultaneous insertion or removal and mutual load sharing.  
       Grouped  
       [0262]     Thus grouped, say, paired detents upon a common transverse handle could be contemplated.  
       Bifurcated  
       [0263]     A bifurcated, split or multiple-limbed detent could be configured, with spaced ‘nose’ limbs at one (leading) end joined by a bridge at one (trailing) end.  
       Stacked  
       [0264]     Vertically and/or horizontally stacked detents, with attendant location apertures could be employed.  
       Chamfer  
       [0265]     Chamfer edged detent surfaces could map a surface transition, preserve some resistance to inadvertent withdrawal, yet facilitate insertion and removal.  
         [0266]     Such a chamfer could be curvilinear—say ‘S’ profile—to soften an otherwise abrupt step transition.  
       Lateral Re-Disposition  
       [0267]     Detent profile could promote transverse or lateral relative post re-disposition, to take up mutual interfit slack or tolerance.  
         [0268]     Thus, for example, an inner post could be urged towards an outer post at one side.  
         [0269]      FIGS. 10A through 11C  reflect a fuller overall picture of flat faced detents in operation with telescopic adjustable support posts of a collapsible platform base container or flat-rack, with diagonal inter-post bracing.  
       Transverse Racking  
       [0270]     In the construction of  FIGS. 10A through 11C , transverse racking of the end-most opposed pair of corner post  70  base elements is countered by a movable cross-bracing gate  71 .  
         [0271]     However, there is no direct bracing of extendible upper (inner) post elements  72 , when deployed well above the corresponding outer base post elements  70 , as in  FIGS. 10A and 11A .  
         [0272]     Thus individual post extensions  72  are free to rack—unless a detent  73  is in situ between extension  72  and associated base elements  70 .  
         [0273]     Captive or entrained detents  70  could be employed in  FIG. 10B , to inhibit complete withdrawal of a detent  73  from a detent aperture  74  in an outer base post element  70 .  
         [0274]     However, this obscures the sightline for an operator seeking to re-align detent apertures  75  of inner upper post element  72  after relative post element re-positioning.  
         [0275]     To counter this, a supplementary modest viewing window  76  is provided over the detent aperture  74  proper—and which has minimal weakening effect upon the overall local post cross-section.  
         [0276]      FIG. 11B  depicts alignment resolution by modest greater local exposure of upper inner extensible post element  72  from a sight line just above a detent aperture  74  in outer base post element  70 .  
         [0277]     Pre-insertion of detent  73  in a detent aperture  74  in the outer base post element  70  relieves the amount of detent travel for full insertion between inner  72  and outer  70  post elements.  
         [0278]      FIG. 11C  depicts alternative detent  73  profile options, from single continuous taper to stepped incremental with intervening taper.  
       Mix &amp; Match  
       [0279]     Features set out herein may be selectively mixed and matched to meet particular requirements—albeit it is not feasible to describe every possible combination or permutation.  
       Component List  
       [0000]    
       
           10  support post  
           11  inner post  
           12  outer post  
           13  capture fitting  
           14  slot (outer)  
           15  slot (inner)  
           20  detent  
           21 A upper bearing surface  
           21 B lower bearing surface  
           22  side  
           30  tapered planform detent  
           31  upper/lower face  
           32  side  
           33  detent nose apex  
           34  capture aperture  
           35  lock pin  
           36  head  
           37  retention (clip) fastener  
           38  lower retention stub  
           39  tolerance  
           43  outer exit aperture  
           44  outer entry aperture  
           45  inner exit aperture  
           46  inner entry aperture  
           50  inclined detent  
           51  upper/lower face  
           52  side  
           53  neck  
           54  locating head  
           64  ‘T’ profile slot  
           70  corner post (outer)  
           71  cross-bracing gate  
           72  inner post  
           73  detent  
           74  outer post aperture  
           75  inner post aperture  
           76  viewing window