EP0691452B1 - Leiter - Google Patents

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Publication number
EP0691452B1
EP0691452B1 EP19950304636 EP95304636A EP0691452B1 EP 0691452 B1 EP0691452 B1 EP 0691452B1 EP 19950304636 EP19950304636 EP 19950304636 EP 95304636 A EP95304636 A EP 95304636A EP 0691452 B1 EP0691452 B1 EP 0691452B1
Authority
EP
European Patent Office
Prior art keywords
ladder
pawl
section
rung
counterbalance
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
EP19950304636
Other languages
English (en)
French (fr)
Other versions
EP0691452A1 (de
Inventor
Trefor Mitchell
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.)
SGB Holdings Ltd
Original Assignee
SGB Holdings Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by SGB Holdings Ltd filed Critical SGB Holdings Ltd
Publication of EP0691452A1 publication Critical patent/EP0691452A1/de
Application granted granted Critical
Publication of EP0691452B1 publication Critical patent/EP0691452B1/de
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
    • E06C7/00—Component parts, supporting parts, or accessories
    • E06C7/06—Securing devices or hooks for parts of extensible ladders
    • 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
    • E06C1/04—Ladders for resting against objects, e.g. walls poles, trees
    • E06C1/08—Ladders for resting against objects, e.g. walls poles, trees multi-part
    • E06C1/12—Ladders for resting against objects, e.g. walls poles, trees multi-part extensible, e.g. telescopic

Definitions

  • the present invention relates to a ladder consisting of at least two ladder sections which can slide relative to each other, the ladder including a pawl mechanism which allows one section to be moved upwards relative to another but prevents the ladder from closing accidentally.
  • Pawl mechanisms of this type are usually provided on multi-section ladders which can be opened by means of rope operation.
  • the pawl is connected to each upper or slide section. As the pawl passes a rung on the lower or main ladder section, it contacts the rung and pivots out of the way to allow the slide section to be raised. After the pawl clears the rung, it falls back under gravity into a position which locks against the rung of the lower or main ladder section, so that the upper or slide section cannot accidentally fall.
  • Pawl mechanisms are known in which the pawl pivots about a point which, when the ladder sections are locked together, is above the rung of the ladder section on which the pawl catches, the pawl swinging out of the way when the ladder section, on which the pawl pivots, is raised.
  • Pawl mechanisms are also known in which the pawl pivots about a point which, when the ladder sections are locked together, is adjacent the rung of the lower ladder section on which it catches, rotation of the pawl in one direction being prevented by the rung of the ladder section on which the pawl pivots.
  • any pawl mechanism engages automatically, to prevent accidental closing of the ladder, for example if the rope being used to raise the ladder is inadvertently released or brakes. It is preferably that the pawl mechanism should act without the need for any springs, and indeed certain British standards do require that latching devices on ladders should not depend on the operation of springs and should instead simply rely on gravity.
  • GB-A-110487 and GB-A-20227 describe ladders with safety pawl arrangements, that of GB-A-110487 seeming to work independently of which way up the ladder is used, but the pawl not engaging a rung of the slide section.
  • the present invention concerns a ladder having a pawl mechanism of the type in which rotation of the pawl is prevented in one direction by one of the rungs of the ladder section on which the pawl is mounted.
  • the object of the invention is to provide a pawl mechanism which allows the ladder to be operated safely which ever way round it is used, i.e. whether the slide sections are at the back or at the front. It is also the object of the invention that the pawl mechanism should operate under gravity, without any spring mechanism.
  • the invention provides a ladder comprising at least two ladder sections, including a slide section and a lower section, the slide section having an inner side adjacent the lower section and an opposite, outer side and the slide section having a pawl mechanism which comprises a pawl pivotally mounted on the inside of one of the rungs thereof, wherein the pawl comprises a free end which extends on the inside of the slide section in order to engage the rungs of the lower section and an opposite end extending over the said rung of the slide section so that downward rotation of the opposite end is limited by the said rung, the pawl mechanism also comprising a counterbalance member pivotally mounted on the slide section about a point below the said rung, the counterbalance member being connected to the opposite end of the pawl such that, upon pivoting of the pawl to allow a rung of the lower section to pass, the counterbalance is pivoted outwardly to maintain the centre of gravity of the pawl mechanism to the outside of the vertical through the pivoting axis of the pawl, which
  • the terms “inside”, “outside”, “inwardly” and “outwardly” etc are used to refer to the sides of the slide section of the ladder relative to the other sections, not relative to a wall against which the ladder happens to be placed. Furthermore, a term such as “inside” is not intended to imply that something is immediately on the inner side of something else, in a direction perpendicular to the length of the ladder section, but simply to indicate that it is nearer to the inside of the ladder than that other thing.
  • the counterbalance member is connected to the ladder pawl by means of at least one link member.
  • the ladder pawl is substantially L-shaped, so that it can enclose the said rung of the slide section. Obviously, part of the ladder pawl itself, and the or each link member, can aid the counterbalancing action of the counterbalance member itself, and this application is not to be interpreted to mean that it is the action of the counterbalance member and nothing else which, under gravity, causes the ladder pawl to pivot back to its safe position, rather than overbalancing.
  • each slide section will generally be provided with a pawl mechanism.
  • the ladder schematically illustrated in Figs. 1 and 2 consists of three ladder sections A, B and C, each of which can slide relative to the others.
  • the two upper or slide sections are lifted relative to the third, bottom section by means of a rope in a conventional manner which need not be described here.
  • Fig. 1 shows the ladder being used a first way round, with the upper or slide sections at the back, nearest to the wall.
  • Fig. 2 shows the same ladder, used the other way round, with the upper or slide sections at the front, furthest from the wall. It is desirable that the ladder can be used safely both ways round, and one example of the pawl mechanism which enables this safe operation is described with reference to Figs. 3 to 6.
  • Fig. 3 shows the three ladder sections, A, B and C, section A being the uppermost slide section, here nearest to the wall.
  • the longitudinal sectional view of Fig. 3 shows the rungs D of the ladder sections.
  • the pawl safety mechanism includes a ladder pawl 1, counterbalance 2 and link bar 3, connecting the ladder pawl and the counterbalance.
  • the ladder pawl is pivotally mounted on the ladder section A by pin 4, the pivoting axis being adjacent rung D' and the edge of ladder section A nearest to the other sections.
  • Counterbalance 2 is pivotally mounted on ladder section A by pin 5, the pivoting axis being below that of the ladder pawl.
  • the link bar 3 is pivotally joined to both the ladder pawl and the counterbalance by pins 6, 7 respectively.
  • the ladder pawl 1 is generally L-shaped in cross-section, with a tread section 8 which, in the "at rest” position of the ladder lies in a plane perpendicular to the length of the ladder (i.e. in a horizontal position when the ladder is directly upright).
  • a return section 9 At the end of the tread section, remote from the end nearest to the other ladder sections B, C is a return section 9, extending substantially perpendicularly to the tread section 8.
  • the free end 10 of the tread section 8 extends out of the space defined by ladder section A so that it catches on the rungs of the adjacent ladder section B, in a conventional fashion.
  • the other end of the tread section 8 and the return section 9 lie, in the at rest position of the ladder, around rung D' of ladder section A. Rung D' prevents the free end of tread section 8 from pivoting in an upward direction.
  • the free end 10 of tread section 8 catches on one of the rungs of ladder section B so that ladder section A cannot move downwardly.
  • Pivot pin 6 is at the free end of return section 9 of the ladder pawl 1. In the at rest position of the ladder, pivot pin 6 is below rung D' of ladder section A; pivot pin 7, and thus the counterbalance 2, lies along the length of the ladder section from pivot pin 5.
  • ladder section A is raised relative to section B and C, generally by means of a rope.
  • Fig. 4 shows ladder section A in a higher position than in Fig. 3, the pawl mechanism passing one of the higher rungs of ladder section B.
  • the ladder pawl 1 should revert to the position shown in Fig. 3, so that downward movement of section A is prevented (at least until such time as it is required to close the ladder, when the ladder pawl is released by means of a conventional release mechanism, for example a rope fixed to the return section 9 of the ladder pawl, or to the link bar 3, which rope passes over a pulley above rung D' and then down to the ground so that the pawl can be lifted in order to allow the ladder sections to close on one another).
  • a conventional release mechanism for example a rope fixed to the return section 9 of the ladder pawl, or to the link bar 3, which rope passes over a pulley above rung D' and then down to the ground so that the pawl can be lifted in order to allow the ladder sections to close on one another.
  • the ladder pawl should return to the position shown in Fig. 3, catching on the rungs of section B, under gravity and without the need for any special spring means etc.
  • Figs. 5 and 6 corresponds to the view of Fig. 3, i.e. showing the ladder in an at rest position with ladder pawl 1 catching on one of the rungs of ladder section B.
  • Fig. 6 corresponds to the view of Fig. 4, showing the ladder pawl 1 in the tilted position which it assumes as it passes one of the rungs of ladder section B, upon ladder section A being raised.
  • the ladder pawl 1, the link bar 3 and the counterbalance 2 can assume the same positions, relative to the rung D' of ladder section A, whatever orientation the ladder is in.
  • the position of the ladder pawl mechanism relative to the vertical alters substantially, by 80° if the ladder is used at an angle of 50° to the horizontal, as in Figs. 3 to 6.
  • FIG. 6 shows that, in the tilted position of the ladder pawl mechanism, the centre of gravity of ladder pawl 1 is above or to the left of pivot pin 4. In other words, the centre of gravity moves closer to the wall as the ladder pawl rotates in an anticlockwise direction (in the view of Fig. 6) which would lead to a risk of the ladder pawl 1 itself overbalancing. If it did overbalance, it would not return to the position shown in Fig. 5 after the rung of section B passed by; ladder section A would thus be in an inherently unsafe, freefall position should the rope being used to raise the ladder be accidentally released.
  • a consideration of Fig. 6 also shows that although the centre of gravity of ladder pawl 1 moves to the left, nearer to the wall, the centre of gravity of the counterbalance 1 moves to the right, away from the wall. Overall, the centre of gravity of the complete ladder pawl mechanism thus remains on the side of the vertical away from the wall, so that the ladder pawl 1 will return to the position of Fig. 5 without any risk of it overbalancing.
  • the pawl 1, link bar 3 and counterbalance 2 extend across substantially the full width of the ladder section A, between the stiles.
  • the pawl, link bar and counterbalance may be formed of extruded aluminium.
  • a pawl 1 and counterbalance 2 can be provided on either side of the ladder section, linked by steel pins 6, 7 extending across the ladder.
  • the pawl and counterbalance pieces may be formed of, for example, either extruded aluminium or cast steel.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Ladders (AREA)

Claims (4)

  1. Eine Leiter mit mindestens zwei Leiterabschnitten (A, B) einschließlich eines Schiebeabschnitts (A) und eines unteren Abschnitts (B), wobei der Schiebeabschnitt eine an den unteren Abschnitt anschließende Innenseite und eine gegenüberbefindliche äußere Seite aufweist und der Schiebeabschnitt mit einem Sperrklinkenmechanismus versehen ist, der eine schwenkbar an der Innenseite einer der Sprossen (D') davon angeordnete Sperrklinke (1) umfaßt, und zwar hat die Sperrklinke ein freies Ende (10), das sich zwecks Erfassung der Sprossen (D) des unteren Abschnitts (B) an der Innenseite des Schiebeabschnitts erstreckt, sowie ein gegenüberbefindliches Ende (9), das sich über die besagte Sprosse (D') des Schiebeabschnitts (A) erstreckt, so daß Abwärtsdrehung des gegenüberbefindlichen Endes durch die besagte Sprosse begrenzt ist, wobei der Sperrklinkenmechanismus auch ein um einen Punkt unterhalb der besagten Sprosse (D') schwenkbar an dem Schiebeabschnitt angeordnetes Gegengewichtsglied (2) umfaßt und das Gegengewichtsglied (2) mit dem gegenüberliegenden Ende (9) der Sperrklinke (1) so verbunden ist, daß das Gegengewicht bei Schwenkung der Sperrklinke, um eine Sprosse (D) des unteren Abschnitts (B) passieren zu lassen, auswärts geschwenkt wird, so daß es den Schwerpunkt des Sperrklinkenmechanismus außerhalb der durch die Schwenkachse der Sperrklinke (1) führenden Senkrechten erhält, welches Ende der Leiter auch immer oben bzw. unten ist.
  2. Eine Leiter nach Anspruch 1, bei der das Gegengewichtsglied (2) mit Hilfe von mindestens einem Verbindungsglied (3) mit der Leitersperrklinke (1) verbunden ist.
  3. Eine Leiter nach Anspruch 1 oder 2, bei der die Leitersperrklinke (1) im wesentlichen L-förmig ist, so daß sie die besagte Sprosse (D') des Schiebeabschnitts umschließen kann.
  4. Eine Leiter nach Anspruch 1, 2 oder 3, die mehr als zwei Leiterabschnitte umfaßt, wobei jeder Schiebeabschnitt mit einem Sperrklinkenmechanismus versehen ist.
EP19950304636 1994-07-07 1995-07-03 Leiter Expired - Lifetime EP0691452B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9413711 1994-07-07
GB9413711A GB2291098B (en) 1994-07-07 1994-07-07 Ladder

Publications (2)

Publication Number Publication Date
EP0691452A1 EP0691452A1 (de) 1996-01-10
EP0691452B1 true EP0691452B1 (de) 1998-05-20

Family

ID=10757974

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19950304636 Expired - Lifetime EP0691452B1 (de) 1994-07-07 1995-07-03 Leiter

Country Status (3)

Country Link
EP (1) EP0691452B1 (de)
DE (1) DE69502545T2 (de)
GB (1) GB2291098B (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR3012841B1 (fr) * 2013-11-04 2016-11-25 Tubesca Comabi Dispositif d'acces en hauteur reglable

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB191320227A (en) * 1913-09-08 1913-12-11 George Alexander Weech Improvements in Safety Clutches for Extension Ladders.
GB110487A (en) * 1917-03-28 1917-10-25 Edwin Thurnham Palmer Improvements in Extension Ladders.
GB172179A (en) * 1920-10-06 1921-12-08 Charles Edward Clewley Improvements in extensible ladders
FR1128984A (fr) * 1955-04-22 1957-01-14 Stabila échelles à coulisse et ferrure pour sa réalisation
US4299306A (en) * 1979-12-07 1981-11-10 Emerson Electric Co. Extension ladder lock

Also Published As

Publication number Publication date
DE69502545D1 (de) 1998-06-25
GB2291098A (en) 1996-01-17
EP0691452A1 (de) 1996-01-10
DE69502545T2 (de) 1999-01-07
GB9413711D0 (en) 1994-08-24
GB2291098B (en) 1997-10-01

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