US3811151A - Joint for collapsible ladders - Google Patents

Joint for collapsible ladders Download PDF

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Publication number
US3811151A
US3811151A US00350156A US35015673A US3811151A US 3811151 A US3811151 A US 3811151A US 00350156 A US00350156 A US 00350156A US 35015673 A US35015673 A US 35015673A US 3811151 A US3811151 A US 3811151A
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US
United States
Prior art keywords
locking
joint
hinge pin
rod portion
portions
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00350156A
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English (en)
Inventor
W Kuemmerlin
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Zarges Leichtbau GmbH
Original Assignee
Zarges Leichtbau GmbH
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Filing date
Publication date
Priority claimed from DE19722217258 external-priority patent/DE2217258C3/de
Priority claimed from DE19732308095 external-priority patent/DE2308095A1/de
Application filed by Zarges Leichtbau GmbH filed Critical Zarges Leichtbau GmbH
Application granted granted Critical
Publication of US3811151A publication Critical patent/US3811151A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E06—DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
    • E06C—LADDERS
    • E06C1/00—Ladders in general
    • E06C1/02—Ladders in general with rigid longitudinal member or members
    • E06C1/32—Ladders with a strut which is formed as a ladder and can be secured in line with the ladder
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T403/00—Joints and connections
    • Y10T403/32—Articulated members
    • Y10T403/32254—Lockable at fixed position
    • Y10T403/32262—At selected angle
    • Y10T403/32319—At selected angle including pivot stud
    • Y10T403/32327—At selected angle including pivot stud including radially spaced detent or latch component

Definitions

  • Biasing means connected to the two part Apr. 11 1972 Germany 2217258 of thc lccklhg hlclhhcl Whlch may he telescopically 973 Germany N 2308095 extended, for urging the locking member into one of l the locking positions.
  • the locking member being guid- 52 11.5.
  • Each flange portion l having at least two openings each one of which is [56] References Cited adapted to be aligned with a mating opening of the other flange portion when the ladder stringers are in a UNITED STATES PATENTS predetermined angular position to receive the project- 26
  • the invention concerns a joint for collapsible ladders wherein two members of the joint are pivotally connected to each other by means of a hinge pin.
  • the two members are each provided with a flange portion and a shaft portion.
  • the pivotal connection is mounted on the flange portion of the two members.
  • the joint forming part of this invention also includes a locking member which is urged by a suitable spring means from a non-locking position into a locking position.
  • the locking member can be manually moved from its locking position against the force of the spring into a nonlocking position and can be returned into a locking position after the ladder stringers have been angularly moved towards each other from one predetermined angular position into a second predetermined angular position.
  • Such a rod portion will push out anydirt, cement or the like which may have accumulated in the opening due to the fact that the rod portion is axially guided as it moves through openings in the flange portions.
  • the position of the rod indicates clearly that the joint is insufficiently locked. A blow by hand on the rod portion then practically always suffices to place this rod portion into the correct locking position.
  • a further advantage resides in that the locking arrangement requires no shaft portions, so that it can be connected with aluminum stringers without difficulty, whereas normally connecting elements with relatively large diameters are required. In the shaft portion of the prior art which includes the locking bolt there is no space for such connecting elements.
  • the joint is provided with a central longitudinal bore or bush in which a guide rod which is connected to the rod portion is guidingly, axially, movably mounted.
  • This arrangement provides a substantial protection against soiling of the guiding arrangement.
  • the arrangement can be provided with a cross beam for manually moving the locking member. It has been found to be of particular advantage to mount the return spring in the longitudinal bore which is defined by the hinge pin preferrably in the annular space between the guide rod and the walls of the bore. In this manner considerable space saving is effected and the return spring is practically completely protected against any accumulation of dirt.
  • a particular advantage of the joint for collapsible ladders in accordance with this invention resides in the space saving that can be effected with the construction.
  • the dimension in the axial direction can be kept at a minimum in that at least one bushing with limited slidability in the longitudinal direction is mounted on the guide rod as well as in the longitudinal channel of the hinge pin in that in addition to the first return spring there are mounted additional springs corresponding in number to the number of bushings.
  • One of the return springs bears at on of its end against the guide rod and with its other end against the bushing and the other return spring bears with one of its end against the bushing and with its other end against the hinge pin in an axial direction.
  • the length of the guide rod and its guiding means can be limited to the axial length of the hinge pin even when, for reasons of constructional reliability, the locking member or the locking members have an axial length which makes it possible that in the locking position both flange portions are completely traversed.
  • a plurality (preferrably two) locking members are diametrically arranged relative to hinge pin and can be manually adjusted by means of a yoke or cross beam which joins the locking members to each other.
  • the distance of their locking rod portions relative to the hinge pin need only be about one half the distance if one locking rod portion is used in order to provide the same load resistance of the joint in its locked position.
  • the overall dimensions of the flange portion can also be significantly smaller as compared to the size of the flange portion of a joint having one single locking member.
  • a further particular advantage of the construction of the invention resides in that it permits, when an actual angular movement of the ladder stringers relative to each other is effected, to preselect the new angular position so that when it is reached the joint is automatically locked.
  • This advantageous feature can be incorporated in the embodiments of the invention having only one single locking member as well as in the embodiments having a plurality of locking members.
  • the feature requires that there are openings in both flange portions which align when a predetermined angular position is reached. It is possible in such an arrangement to position the locking rod portion or portions into one opening or openings of one flange portion before the ladder stringers are moved into the new angular position without thereby locking the joint.
  • the locking is effected automatically by means of the force of the return spring only when the new angular position is reached, because only then when this position is reached are the openings of the two flange portions aligned with each other and permit the passage of the locking rod portion or portions.
  • Such a preselection of the new angular position and the automatic locking in the new angular position is even possible when at least two locking rod portions are used, as long as the openings in the flange portions are arranged in such a way that the passage of the locking rod portion is only possible when the correct angular position of the ladder stringers is reached.
  • the locking rod portions have different cross sectional areas and the mating openings in the flange portions have corresponding cross sectional areas thereby assuring passage of the locking rod portions only when the correct angular position is assumed.
  • the distances of the locking rod portion from the hinge pin can be different while the locking rod portion cross sections and corresponding openings can be identical. In this way the same result is achieved.
  • FIG. 1 is a partial side elevational view of a first embodiment in which the ladder stringers and the joint are in an angular position relative to each other adapted for transporting the ladder;
  • FIG. 2 is a partial elevational side view of the joint illustrated in FIG. 1 wherein the ladder stringers are in an angular position relative to each other which corresponds to a working position of the ladder;
  • FIG. 3 is a partial side elevational view of the first embodiment of the joint wherein the ladder stringers are in an angular position relative to each other which corresponds to the second working position of the ladder;
  • FIG. 4 is a cross sectional view along line IV--IV in FIG. 3 at a larger scale than FIG. 3;
  • FIG. 5 is a partial side elevational view of a second embodiment of a joint for collapsible ladders, in accordance with the invention, wherein the ladder stringers are in a non-working position that is adapted for transportation;
  • FIG. 6 is a partial side elevational view of the joint illustrated in FIG. 5 wherein the ladder stringers are in an angular position corresponding to a first working position of the ladder;
  • FIG. 7 is a partial elevational side view wherein the ladder stringers are shown in a second angular position relative to each other corresponding to a second working position of the ladder;
  • FIG. 8 is a cross sectional view along line IV-IV in FIG. 7 wherein the parts are shown in a larger scale;
  • FIG. 9 is a partial elevational side view of a third embodiment of a joint in accordance with the invention, wherein the members of the joint are shown in an angular position corresponding to a second working position of the ladder stringers in which the ladder is fully extended;
  • FIG. 10 is a cross sectional view along line X-X of FIG. 9 wherein the parts are shown in a larger scale;
  • FIG. 11 is a cross sectional view similar to FIG. 10 illustrating a fourth embodiment of the joint for collapsible ladders forming part of this invention wherein the joint is shown in a locked position;
  • FIG. 12 is a cross sectional view corresponding to FIG. 11 of the fourth embodiment of the invention whereinthe joint is shown in an unlocked position.
  • the joint includes two members 2 and 3 which are pivotally connected to each other by means of a hinge pin 1.
  • the members 2 and 3 may consist of aluminum sheet metal but can also be made of any other suitable material.
  • Each member 2 and 3 includes'a flange portion 4, 5 and a shaft portion 6, 7, the latter being adapted to be joined to the ladder stringers.
  • the two shaft portions 6 and 7 are preferably in the illustrated embodiment formed in the shape of a square tube which for facilitating the mass manufacture is formed of two U-portion 6' respective 6" and 7 respectively 7". If the ladder stringers are also formed by square shaped aluminum tubes, it is advantageous, to provide the two shaft portions 6 and 7 with two bores 8 and 9 of relatively large diameters.
  • the aluminum tubing which forms the stringers can then be joined by means of hollow rivets which extend through the shaft portions, the diameter of which corresponds to the di ameter of the bores 8 and 9, thereby forming a strong connection and eliminating for all practical purposes the danger of failure of the joint.
  • the total width in the longitudinal direction of the shaft portions 6 and 7 is equal double the width of the sheet metal which has been selected for making the members 2 and 3.
  • the shaft portion 7 is made of the U-shaped portions 7' respectively 7" which form a unit and which have the bores 9.
  • a locking between the members 2 and 3 is carried out by means of a locking arrangement, which includes a locking rod 10, having a locking rod portion and a guide rod 11 which is axially slidably guided in the central bore 12 of a' hinge pin 1.
  • the bore 12 has an enlarged portion for accommodating three compressed coil springs 13 which bears with one of its end against the shoulder defining a narrow portion of the bore 12 and at the other end against an enlarged collar 14 of the guide rode 11.
  • the length of the hinge pin 1 is selected in such a way that the collar 14 is in all positions of the locking rod portion situated in the bore 12.
  • a shoulder 15 of the guide rod 11 prevents the return spring 13 from moving the guide rod 10 beyond a predetermined locking position in which the yoke or cross beam 25 is still located at a sufficient position from the flange part 4' to permit the manual grasping of the yoke or cross beam 25. It is thus possible by a simple manipulation of the yoke 25 to adjust the locking rod 10.
  • the hinge pin 1 of the first embodiment is secured against axial displacement by means of two oppositely spaced rings 16 which are mounted in mating grooves in the hinge pin 1. Furthermore the hinge pin 1 is provided with a lateral flat cut portion which bears against a mating flat surface in the flange parts 4 and 5, thus securing the hinge pin 1 against rotation.
  • the hinge pin 1 has just enough axial length to accommodate the guide rod 11 and to securely guide it as well as to accommodate the coil springs 13. Thus due to the combination wherein the hinge pin extends axially bilaterally beyond the width defined by the flange portions 4 a space saving arrangement is provided.
  • each flange part 4' there are provided in each flange part 4', 4" a bore 17, which are aligned relative to each other.
  • the diameter of the bores 17 is slightly larger than the diameter of the locking rod portion 10'.
  • the flange part 5 is provided with a longitudinal slot 18 extending in a circumferential direction, the width of which corresponds to the diameter of the bores 17 and one end of which overlaps completely with the bores 17 when the shaft portion 6 and 7 assume an acute angle as illustrated in FIG.
  • said acute angle corresponding to the angle which the ladder stringer assume when thy are in a normal working position, that is in a position where the ladder forms a step ladder.
  • the other end of the longitudinal circumferential slot 18 overlaps with the bore 17 when both shaft portions 6 and 7 are situated parallel to each other. This position corresponds to the position wherein the ladder is ready to be transported.
  • the locking rod 10 can, in this position, pass through the bores 19, 20 and 21, and thereby lock the joint in position.
  • special bores for locking the joint in the position illustrated in FIG. 3 it is possible, when the members 2 and 3 ought to be moved relative to each other from the position illustrated in FIG. 2 to the position illustrated in FIG. 3, to preset the locking rod 10 into the bore 19.
  • the locking rod portion 10 then passes automatically into the bore 21 and the bore 20, as soon as the position illustrated in FIG. 3 is reached by the members.
  • FIGS. 5-8 illustrate a second embodiment of the joint of the invention. Since the variation from the first embodiment resides primarily in the provision of a second locking rod portion, the reference numerals have not been changed for those parts and portions of the arrangement which have not changed relative to the embodiment of FIGS. 1 to 4 so that these parts and portions are referred to with the same reference numerals as in the first embodiment and are not described in detail herein-below.
  • a second locking rod portion 1 Diametrically opposite to the locking rod portion 10 and parallel to it as well as parallel to the guide rod 11 there is provided a second locking rod portion 1 10. The distances between both locking rod portions 10 and 110 relative to the guide rod 11 are equal.
  • the yoke 125 joins the locking rod portions 10' and 1 10 with the guide rod 11 at one of its ends.
  • the second locking rod portion 110 has a circumferential cross section as has the first locking rod portion 10'. As can be noted clearly from FIG. 8, however, the diameter of the locking rod portion 10' is substantially smaller than the diameter of the locking rod portion 110.
  • both flange parts 4 and 4" at a distance from the joint axis, corresponding to the distance of the longitudinal axis of the locking rod portion 110 from the joint axis, diametrically opposite to the bores 17 in each flange part a bore 117 which overlap each other completely.
  • the diameter of these bores is slightly larger than the exterior diameter of the locking rod portion 110 so that there exists a play between the latter and the walls of the bores 1 17 thereby facilitating an easy introduction and removal of the locking rod portion 110.
  • Diametrically opposite from the longitudinal circumferential slot 18 there is provided in the flange portion a longitudinal circumferential slot 118. The width of this circumferential slot in the radial direction is equal to the diameter of the bore 117.
  • One end of the longitudinal slot 118 overlaps completely with the bore 117, when both of the shaft portions 6 and 7 assume the angular position illustrated in FIG. 6.
  • the other end of the longitudinal circumferential slot 118 overlaps with the bore 117, and both of the shaft parts 6 and 7 extend parallel and next to each other.
  • the bores 119 and 120 are offset relative to the bore 117.
  • both of the bores 119 and 120 are overlapped with a bore 121 in the flange portion 5, that is they have their wall surfaces aligned with each other.
  • the locking rod portion then passes through the bores 19, 20 and 21 whereas the locking rod portion 110 can pass through the bores 119, 120 and 121 thereby locking the joint.
  • locking rod portions with different cross-sectional areas it is also possible to provide locking rod portions with equal cross-sectional areas if the locking rod portions are differently radially spaced from the axis.
  • This variation of the invention is illustrated in a third embodiment (6, 9 and 10).
  • a yoke 225 which joins the guide rod 211 with the locking rod portions 210, 210' having equal diameters.
  • the distance of the locking rod portion from the guide rod 211 is smaller as the corresponding distance of the locking rod portion 210.
  • these different distances are required so that the corresponding locking rod portions between the bores and longitudinal circumferential slots in both flange portions 203 and 205 are correspondingly located.
  • they are arranged in suitable locations the bores 217, 219, 220 and 221 as well as the longitudinal circumferential slot 18 for coaction with the locking rod portion 210 and the bores 217, 219', 220', 221 as well as longitudinal circumferential slot 218 which coact with the locking rod portion 210.
  • the relative positions of these bores and longitudinal circumferential slots is identical to the bores and slots described in relation to the locking rod portion 10 respectively 110 described in connection with the embodiment of FIGS. 7 and 8.
  • the locking rod portions 210 and 210' can with their free ends be placed into the bores in the flange portion 204 by manually handling the yoke 225 before the axial swinging movement of the members is effected, whereby an automatic locking of the joint in the newly selected regular position is effected.
  • the person using the ladder has both hands free for carrying out the swinging movement.
  • the embodiment is in principle constructed identically to embodiments described hereinabove.
  • the two members 202 and 203 are somewhat differently shaped in FIGS. 9 and 10 this I in no way affects the basic inventive concept of the locking arrangement and is therefore not described in detail, in particular since the members forming the joint as well as the hinge pin 201 and the guid rod 211 can be constructed identically to theconstruction of the preceedingly described embodiments.
  • Both of the flange portions 304 and 305 are pivotally connected to each other by means of a hinge pin 301.
  • This hinge pin is constructed in the form of a bushing and has on the side which faces the two locking rod portions 310 and 310', which are joined by a yoke 235, a collar portion 329 which extends into the central bore 312.
  • the radial height of this collar portion 329 is somewhat larger than the wire thickness of the coils of a first return spring 313, said return spring 313 being mounted within the bore 312 and has an interior diameter, which is somewhat larger than the interior diameter of the collar portion 329.
  • a bushing 326 is mounted in the bore 312 and has an axial length that is equal to the axial length of the hinge pin 301.
  • the exterior diameter of the bushing 326 is so demensioned that it can easily but without large play be slidably moved into the axial direction within the hinge pin.
  • the end of the bushing 326, which is situated within the collar portion 329, when the latter is completely pushed inside of the hinge pin, has in turn an interiorily projecting collar portion 327, whereas the opposite end is provided with an exteriorly projecting collar portion 328.
  • the radial height of the collar portion 328 is approximately equal to the radial height of the collar portion 329 due to this arrangement the bushing 326 is guided when being actually moved by the collar portion 329 as well as by the collar portion 328. Both of these collars also serve for supporting surfaces for the precompressed coil spring 313, which is mounted in the annular space between the bushing 326 and the interior wall surfaces of the hinge pin 301.
  • the guide rod 311 extends within the bushing 326, the diameter of the guide rod 311 being somewhat smaller than the interior diameter of the collar portion 327 of the bushing 326, so that an axial displacement relative to the bushing 326 can be easily effected without large play.
  • the guide rod 311 has at its free end a radially outward projecting collar portion 314, the radial height of which is equal to that of the collar portion 327.
  • a second, similarly precompressed coil spring 313 is mounted within the annular space between the guide rod 311 and the bushing 326 and abuts, on the one hand against the collar portion 327, and on the other hand, against the collar portion 314.
  • Both of the coil return springs tend to maintain the bushing 326 as well as the guide rod 311, and thereby also both locking rod portions 310 and 310, in the position illustrated in HQ 11, which is the locking position.
  • the yoke 325 prevents a further displacement of the bushing and the guide rod towards the right as viewed in FIG. 11. Since both of the return coils springs 313 and 313 can only be compressed to the extent when their individual helical coils abut against each other, the bushing 326 can only be partially pulled out from the hinge pin 301 and the guide rod 311 can only be partially pulled out from the bushing 326. However, both of these axial displacements suffice to move the locking-rod portions 310 and 310' out of their locking position in which they are situated in corresponding bores, as is shown in FIG. 12.
  • the bores and longitudinal circumferential slots for accommodating the locking rod portions are arranged and constructed similarly to the arrangement and construction of the embodiment illustrated in FIGS. 9 and 10. The same applies to the other parts of the joint. Therefor a detailed description of the other features of the joint construction is not necessary.
  • a joint for collapsible ladders comprising in combination;
  • a hinge pin extending at least partially through said flange portion of each member for forming a pivotal connection between said two members
  • each member being adapted to be connected to a ladder stringer of the collapsible ladder
  • a locking member comprising at least one locking rod portion and one guide rod portion which are parallel and which are adapted to be moved from a locking position to a non-locking position and viceversa; said ladder stringers and two members being swingable about said hinge pin relative to each other when said locking member is in a non-locking position;
  • said guide rod portion being guidingly axially movable in said hinge pin from said looking to said nonlocking position and vice-versa;
  • biasing members operatively connected to said guide rod portion for urging it into said locking position
  • each member having at least two openings each of which is adapted to be aligned with a mating opening in the other flange portion and said locking rod portion being adapted to pass through said openings to lock said two members in a predetermined angular position relative to each other.
  • said locking member includes two locking rod portions which are parallel to said guide rod portion and are connected to it by a manually adjustable yoke member.
  • both of said locking rod portions are equally radially spaced from said hinge pin but have different cross-sectional areas and said openings in said flange portions having corresponding different crosssectional areas so that an alignment of openings of the same size in said flange portions permits the passage of a mating guide rod portion therethrough.
  • both locking rod portions are formed as round-shaped rods of equal diameter, and said openings in said flange portions have a width in the radial direction which corresponds substantially to the diameter of the coacting locking rod portion.
  • said biasing means is formed as a coil spring, said guide rod portion defining an annular space within said central bore of said hinge pin, and said coil spring being axially disposed within said annular space.

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US00350156A 1972-04-11 1973-04-11 Joint for collapsible ladders Expired - Lifetime US3811151A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19722217258 DE2217258C3 (de) 1972-04-11 Gelenkbeschlag für klappbare Leitern
DE19732308095 DE2308095A1 (de) 1973-02-19 1973-02-19 Gelenkbeschlag fuer klappbare leitern

Publications (1)

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US3811151A true US3811151A (en) 1974-05-21

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Application Number Title Priority Date Filing Date
US00350156A Expired - Lifetime US3811151A (en) 1972-04-11 1973-04-11 Joint for collapsible ladders

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US (1) US3811151A (en:Method)
CH (1) CH551560A (en:Method)
FR (1) FR2328099A1 (en:Method)
SE (1) SE374582B (en:Method)

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SE374582B (en:Method) 1975-03-10
FR2328099A1 (fr) 1977-05-13
CH551560A (de) 1974-07-15
FR2328099B1 (en:Method) 1978-05-26

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