AU2007229411B9 - A Stabilizer for a Ladder - Google Patents

Description

A STABILIZER FOR A LADDER

Field of the invention [001 ] This invention relates to stabilizing ladders.

[002] A common cause of injury to people using ladders is that the ladder topples over when the person leans too far to one side

Background of the invention [003] Various forms of outrigger support have been used to stabilize ladders. These consist of an additional pivotable leg which can be deployed to the side of the ladder in use. However, these can be cumbersome to use and difficult to correctly set up and can be costly to manufacture, and may become expensive to the end user.

[004] Any reference herein to known prior art does not, unless the contrary indication appears, constitute an admission that such prior art is commonly known by those skilled in the art to which the invention relates, at the priority date of this application.

Summary of the invention [005] The present invention provides a pivotable telescopic auxiliary leg for a ladder, the ladder having at least first and second legs, the auxiliary leg including at least a first segment and a second segment, the first and second segments being mutually telescopically slidable between retracted and deployed states, the first segment being adapted to be pivotably connected at its upper end to an associated leg of the ladder, and a pivot arm having a pivot connexion adapted for connexion to said associated leg of the ladder, the pivot arm being pivotably connected to the second segment, whereby, as the auxiliary leg is extended, the pivot arm pivots from the associated leg of the ladder and pivots in relation to the auxiliary leg and wherein the auxiliary leg is automatically lockable into the deployed state after the first and second segments are released from the retracted state and automatically lockable in the retracted state after the first and second segments are retracted from a deployed state.

[006] There can be included a first latch arrangement which is adapted to releasably latch the auxiliary leg in one or more deployed states.

[007] The pivot arm and the auxiliary leg can be dimensioned so that, when the auxiliary leg is deployed, the auxiliary leg is in an auxiliary leg latching position.

[008] A second latch arrangement can be provide which is adapted to latch the first and second segments in the retracted state.

[009] The second latch arrangement can latch the pivot arm to a lower one of the segments.

[010] The auxiliary leg can be one or more than one of the following: adapted to be automatically locked into the deployed state after the first and second segments are released from the retracted state; adapted to be automatically locked in the retracted state after the first and second segments are retracted from a deployed state.

[011] The auxiliary leg can include an auxiliary leg travel limiter arrangement which prevents one or more of the following: the auxiliary leg from being pivoted beyond an auxiliary leg limit angle; the auxiliary leg from being pivoted beyond an auxiliary leg limit angle wherein a first limit angle is greater than an auxiliary leg latching angle.

[012] The auxiliary leg can include a pivot arm travel limiter arrangement adapted to do one or more of the following: limit the angle of deployment of the pivot arm; limit the deployment angle of the pivot arm to an angle greater than a pivot arm latching angle.

[013] The first latch arrangement can include a first spring loaded latch element connected to one segment of the auxiliary leg, and adapted to cooperate with corresponding first latch recess means on the other segment.

[014] The first and second segments can be one or more of the following: tubular; telescoping;.

[015] The auxiliary leg can include raised longitudinal ribs or beads on the inner wall of an outer segment and or on the outer wall of the inner segment. There can be two or more raised beads.

[016] The cross section of the first and second segments can be such that an outer segment and an inner segment are one of the following: circular, or square, or rectangular, or oval.

[017] The auxiliary leg can include an additional locking pin is provided to lock the auxiliary leg in a deployed state.

[018] The first and second segments of the auxiliary leg can latch in the deployed state to form a triangle with the pivot arm and the corresponding leg of the ladder.

[019] The auxiliary leg can include a captive releasable latch arrangement adapted to do one or more of the following: hold the auxiliary leg in the deployed state; hold the pivot arm in a retracted state.

[020] The present invention also provides a ladder including one auxiliary leg as described above. The ladder can include a second auxiliary leg as described above.

[021 ] The ladder can have the first and second auxiliary legs located at opposed side locations on the ladder.

Brief description of the drawings [022] An embodiment or embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [023] Figure 1 shows a ladder with auxiliary legs according to an embodiment in the folded position; [024] Figure 2 shows the ladder of Figure 1 with the auxiliary legs deployed; [025] Figure 3 shows an isometric view of the ladder with another auxiliary leg arrangement; [026] Figure 4 shows cross sectional detail of a telescopic tube arrangement; [027] Figure 5 shows a partial view of a tube; [028] Figure 6 shows a latch arrangement adapted for use with the embodiments; [029] Figure 7 shows across section of an oval telescopic leg arrangement; [030] Figure 8 illustrates a further auxiliary leg arrangement; [031 ] Figure 9 is a side view of the auxiliary leg arrangement of Figure 8; [032] Figure 10 illustrates a modified latch arrangement; [033] Figure 11 illustrates a cross section of an oval telescopic leg arrangement similar to Figure 7, with two ribs or beads; [034] Figure 12 illustrates a cross section of an oval telescopic leg arrangement similar to Figure 7, with three ribs or beads; [035] Figure 13 is an inverted view of the pivot arm showing the strike plate feature; [036] Figure 14 illustrates an alternative pivot arm configuration; [037] Figure 15 is a top view of the pivot arm of Figure 14; [038] Figure 16 shows the pivot arm of Figure 14 connected to an extending support leg; and [039] Figure 17 is a schematic illustration of the pivot arm of Figure 14 in use.

Detailed description of the embodiment or embodiments [040] Figure 1 shows a ladder fitted with a pair of auxiliary legs. The ladder includes a plurality of rungs or steps connected between a pair of legs 102, 104.

[041] An auxiliary leg includes a pair of telescopic leg segments 108,110, with the lower segment 110 adapted to slide inside the upper segment 108 in this embodiment. Of course, the upper segment could be adapted to slide within the lower segment without departing from the inventive concept.

[042] The upper segment 108 is pivotably connected to the associated ladder leg 102 via pivot connexion 106.

[043] A pivot arm 116 is pivotably connected to the ladder leg 102 via pivot connexion 114, and to lower segment 110 via pivot connexion 112. The pivot arm 116 as shown in Figure 1 is a single member and does not collapse or fold upon itself.

[044] Thus the ladder leg 102, the pivot arm 116, the upper segment 108, and the lower segment 110 are connected by three pivot connexions, 106, 112,114, and a sliding engagement between the segments 108, 110. However, when the two segments 108,110 of the auxiliary leg latch in the extended or deployed state, the limbs 102, 108, 110, 116, form a triangle which provides dimensional stability.

[045] The embodiments provide a latching means to retain the auxiliary leg in the extended or deployed state and one to retain the auxiliary leg in a retracted or folded state.

[046] The specification also describes alternative means for retaining the leg in the “folded” configuration or state. The term “folded” is used here to indicate that the telescoping segments of the auxiliary leg are in a non-extended or non-deployed state. In a first alternative, the auxiliary leg can be retained in the folded state by a latch pin arrangement locking the two segments of the auxiliary leg in the folded state. In a second alternative, a latch pin on the lower segment of the auxiliary leg can engage a hole in the pivot arm in the folded state.

[047] A first latch arrangement 122 interacting with holes 120 can be provided to hold the segments 108, 110 in the deployed position. Alternatively, a second latch arrangement 126 can be used to hold the outrigger leg in the folded position.

[048] A releasable latch arrangement 126 can serve to hold the auxiliary leg to the ladder leg 102 when not in use. Various forms of clamp can be used. However, according to an embodiment of the invention, the clamp member is of a similar design to the clamp arrangement used to latch the telescopic leg segments in the deployed position. The latch arrangement 126 is described and illustrated in more detail in Figure 8 at 824, 826.

[049] Figure 2 illustrates the ladder of Figure 1 with the auxiliary legs deployed.

[050] To deploy the auxiliary legs, the latch 126 is disengaged and the pivot arm is pivoted outward from the ladder leg 102. As latch 122 is in a disengaged state, the segment 110 drops under gravity, restrained by the friction between the segments 108, 110, and the angle of inclination of the auxiliary leg.

[051 ] As show in Figure 2, the lower segment 210 slides down until the latching holes or arrangement 220 is engaged. This is a latch which engages automatically. An embodiment of a suitable latch is shown in Figure 6.

[052] Thus the auxiliary leg will drop and latch into the deployed position without the need for the user to manually engage the latch mechanism.

[053] Similarly, in retracting the auxiliary leg, the user disengages the latch 220 and pushes the lower segment into the upper segment. At the same time, the geometry of the pivot arm and the segments of the auxiliary arm is such, as is described later, that the latch 126 also engages. Thus the retracting of the auxiliary leg is also simplified. If desired, instead of using the latching arrangement 126, the latch 122 can be provided to retain the leg in the folded state.

[054] Figure 3 shows a variation of the embodiment of Figure 2, in which the pivots 306, 314,312 are mounted so that the auxiliary leg deploys at an angle Θ out of the plane of the ladder legs 302,304. In other respects, this arrangement operates as for the embodiment described with reference to Figures 1, 2, 8 and 9.

[055] The auxiliary leg can be used with either extension ladders or step ladders. While the extension leg can have a fixed footing, a further variation includes an additional extension to the lower segment below the pivot point 112, 212, 312 so the auxiliary leg can be adapted to allow for uneven footings. The extension can be a screw adjustment, or a telescopic or sliding extension, or other suitable extension. Figures 8 and 9 show a threaded adjustment 840, 940. If desired the screw adjustment can include a swivel pad or a ball joint type termination, to take account of uneven surfaces.

[056] One or more intermediate latching positions can be provided on the auxiliary leg. These latching positions can be implemented by a similar automatic latch as used for the latches 120, 126.

[057] Figure 4 is an end view of a square section telescopic arrangement having a square outer tube 402, and a square section inner tube 404. The inner tube 404 is a clearance fit within the tube 402. Projecting ribs or beads 406 are provided to provide a sliding surface between the inner and outer tube. These ribs or beads provide a reduced contact surface between the tubes. The ribs can be formed on the outer surface of the inner tube, the inner surface of the outer tube, or on both surfaces.

[058] Figure 5 is a partial view of an inner tube provided with longitudinal ribs or beads 506.

[059] The ribs or beads 406, 506 can have a rounded profile. The contact between the beads and the surface of the other tube is then approximately line contact.

[060] Various arrangements of beads or ribs are within the scope of the invention.

[061] Figure 6 shows a latch arrangement suitable for use in latching the auxiliary legs.

[062] The arrangement includes a captive latch arrangement including a latch pin 634, and a spring 636 which engages the latch pin 634. The spring is located within the inner tube 610. The spring 636 operatively engages the latch pin 634. In the embodiment shown in Figure 6, the spring 636 passes through a hole 624 in the latch pin 634. The spring may extend from the hole 624.

[063] In the latched state, a latch pin 634 is held in place in hole 616 in outer tube 612 by spring 636. The user can move the latch pin 634 out of engagement with hole 616 by pushing it from its first position shown in solid line to its second position shown in dotted outline against the spring force.

[064] The entrance to the hole 616 may be chamfered to facilitate engagement of the latch pin 634 with the hole 616. Alternatively, the latch pin can have a rounded end to facilitate engagement.

[065] The spring can be a spring steel or phosphor-bronze spring or it can be made of other suitable resilient material. Alternatively, the spring latch can be made from one piece of spring steel. The spring can have a flat cross section.

[066] Figure 7 shows an oval shaped telescopic leg arrangement 700 having an outer tubular segment 702 and an inner tubular segment 704. The outer segment 702 includes a number of longitudinal beads 706, 708, 710 on its inner wall. The inner segment includes a number of longitudinal beads 712, 714, 716 on its outer wall. As shown, the arrangement of the two sets of beads is complementary.

[067] Figure 8 illustrates an embodiment of the auxiliary leg in which the upper segment 808 slides within the lower segment 810. A number of latch holes 826 are provided to allow adjustment of the auxiliary leg to accommodate uneven surfaces.

[068] The latching aperture 825 is used to latch the auxiliary leg in the retracted or folded state by engaging with the optional latching pin 824.

[069] An alternative arrangement for latching the auxiliary leg in place when not in use is also shown in Figure 8. In Figure 8, the pivot arm 816 is in a form of a ‘U’ shaped channel to connect pivot connexions 812, 814, attaching the ladder leg 802 and the lower segment 810. An additional latch pin/spring arrangement 824 is provided in auxiliary leg segment 810, and a complementary latch hole 825 is provided in pivot leg 816. These are equidistant from pivot point 812, so that they are overlying when the auxiliary leg is folded against the ladder leg. The pivot arm 816 is a channel which includes a latch hole 825 adapted to engage with the latch pin 824 when the auxiliary leg is folded against the leg of the ladder. A strike plate” formation 823 can be provided on the pivot arm to provide a smooth engagement between the latch pin 824 and the hole 825. This is illustrated in more detail in Figure 13. The latch pin 824 and hole 825 serve to hold auxiliary leg against the ladder leg when the auxiliary leg is not in use. Alternatively, flat bar can be used for the pivot arm.

[070] Figure 13 is a partial view of a pivot arm (inverted in relation to Figure 1) showing detail of the strike plate. The pivot arm 1302 is in the form of a channel having side walls 1304,1306 and a base 1308. A cutout 1314 in the base enables the arm to be fitted to the ladder leg at one and, and a similar cutout at the other end (not shown) facilitated fitting to the auxiliary leg. Pivot holes 1310, 1312 are provided for attachment to he ladder leg, and similar pivot holes(not shown) are provided for attachment to the auxiliary leg. The wall 1306 includes a latch hole 1325 adapted to receive the latch pin 824, 924 from the auxiliary leg segment. The strike plate 1323 provides a tapered engagement between the latch pin 824,924 and the wall 1306 so that the latch pin is gradually depressed as the pivot arm is folded over the auxiliary leg segment. This prevents the latch pin from obstructing the closure of the pivot arm over the auxiliary leg segment.

[071 ] In a further alternative embodiment, the function of the latch pin 834,934 can be performed by the holding pin 824, 924 by providing an extended length latch pin which is located to engage with latch hole 825 in folding arm 816 when the auxiliary leg is withdrawn.

[072] Figure 9 is a side view of the arrangement of Figure 8 with an X-ray view of the latch pin 934 and spring 936. As shown at 916, the pivot arm can have a profiled portion to facilitate engagement with a latching arrangement such as 126 in the retracted state. The arrangement of Figures 8 & 9 can be folded by the user depressing the latch button 834,934 and pushing the lower portion 810 of the outrigger leg up over the upper portion 808.

[073] Figure 10 shows a modified version of the latch arrangement of Figure 6 in which the latch pin is replaced by a latch element 1035 formed integrally with the spring 1036. This latch element can be depressed through the hole 1016 in the outer segment 1012 to release the inner segment 1010 as shown by the dotted deflection of the spring 1036.

[074] Illustrated in Figures 11 and 12 are cross sections similar to that illustrated in Figure 7. The cross sections of Figures 11 and 12 show beads or ribs only on the outside of the inner tubular segment, with only two ribs or beads 1106, 1108, in Figure 11 and three 1206, 1208, 1210, in Figure 12. Depending upon the strength and other characteristics of the material used the cross-sectional thickness of the tubular segments might need to be in increased so that the respective segments will not twist and or jam during use, due to the decreased numbers of ribs, by comparison to other arrangements described above.

[075] Figure 14 shows an alternative form for the hinged arm 1408 having a hinge 1402 attachable to the ladder leg via hinge screw plate 1404 and to the arm 1408 by screw plate 1406. The arm has a tapered shape with its wide end adapted for attachment to the ladder leg via screw plate 1404. The broader connection with the ladder leg provides a larger load bearing surface.

[076] The narrow end of arm 1408 is adapted for connection to the extendible leg via pivot arms 1416, 1418, having pivot pin holes 1420. The pivot arms 1416, 1418 and the edge 1422 of the arm 1408 define a recess adapted to receive the cross-section of the lower portion of the extendible leg.

[077] The arm 1408 is provided with vertical load bearing capacity by the skirts such as 1410 which, in this embodiment, are extensions of the pivot arms 1416,1418. A convex camming projection 1412 is formed in the skirt 1424 to engage the spring latch 1615 in Figure 16, so that it can releasably latch into hole 1414.

[078] Optionally, a skirt 1424 can be extended in an inclined manner as shown at 1425 to form a contact projection which engages the ladder leg and determines the maximum angle at which the arm can be deployed. This creates the obtuse angle β of Figure 17 and enables the arm 1408 to be folded automatically by pushing the extendible leg towards the ladder leg while depressing the upper latch button. A mirror image arm is used for the opposite auxiliary leg.

[079] Figure 15 is a top view of the arm 1508. The tapered edge 1526 of the arm and the camming projection 1512 can be seen in this view.

[080] A leg gripping flange 1482, 1582, 1682 can be provided to retain the leg against the skirt in the folded position. This holds the leg against the side wall 1424 and helps prevent the latching arrangement 1614,1615 from becoming disengaged unintentionally when the ladder is being moved. A section 1550 of the auxiliary leg is shown in dash-double dot outline. The distal end of the flange can be flared or bevelled to facilitate the reception of the leg into the interference fit between the flange 1482 and the wall 1424. The flange 1482 can be formed by a partial cut-out 1480, 1580, 1680. The cut-out can have a D shape.

[081 ] Figure 16 shows the arm of Figures 14 & 15 attached to a ladder leg 1640 and the lower segment of extendible leg 1650. The arm 1608 is connected to the ladder leg 1640 via screw plate 1604, and to the extendible leg via pivot arms only one of which is shown at 1616. The camming projection is the same distance from the pivot pin 1620 as the spring latch member 1615, so that, in the folded position (not shown) the latch 1615 will be compressed by the camming projection 1612 until it engages hole 1614, where it releasably holds the extendible leg in the “closed” position until the user depresses the latch 1615 from the hole 1614 and extends the extendible leg.

[082] In practice, the arm 1608 can be arranged so that, in the open position, the leg 1650 can be pushed in towards the ladder leg 1640 and the arm 1608 will automatically fold upwards.

[083] Figure 17 is a schematic illustration of the arm in use. The end 1725 of the skirt of the arm 1708 is angled to limit the rotation of the arm away from the ladder leg 1740. The arm 1708, the ladder leg 1740, and the extendible leg 1750 form a triangle. The angle β between the arm 1708 and the extendible leg is preferably an obtuse angle, while the angle between the arm 1708 and the ladder leg 1740 is preferably an acute angle. This arrangement facilitates folding of the arm by pushing the extendible leg 1750 towards ladder leg 1740.

[084] Where ever it is used, the word “comprising” is to be understood in its “open” sense, that is, in the sense of “including”, and thus not limited to its “closed” sense, that is the sense of “consisting only of’. A corresponding meaning is to be attributed to the corresponding words “comprise”, “comprised” and “comprises” where they appear.

[085] It will be understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text. All of these different combinations constitute various alternative aspects of the invention.

[086] While particular embodiments of this invention have been described, it will be evident to those skilled in the art that the present invention may be embodied in other specific forms without departing from the essential characteristics thereof. The present embodiments and examples are therefore to be considered in all respects as illustrative and not restrictive, and all modifications which would be obvious to those skilled in the art are therefore intended to be embraced therein.

Claims (20)

1. Claims

   1. A pivotable telescopic auxiliary leg for a ladder, the ladder having at least first and second legs, the auxiliary leg including at least a first segment and a second segment, the first and second segments being mutually telescopically slidable between retracted and deployed states, the first segment being adapted to be pivotably connected at its upper end to an associated leg of the ladder, and a pivot arm having a pivot connexion adapted for connexion to said associated leg of the ladder, the pivot arm being pivotably connected to the second segment, whereby, as the auxiliary leg is extended, the pivot arm pivots from the associated leg of the ladder and pivots in relation to the auxiliary leg and wherein the auxiliary leg is automatically lockable into the deployed state after the first and second segments are released from the retracted state and automatically lockable in the retracted state after the first and second segments are retracted from a deployed state.
2. 2. A pivotable telescopic auxiliary leg as claimed in claim 1, including a first latch arrangement which is adapted to releasably latch the auxiliary leg in one or more deployed states.
3. 3. A pivotable telescopic auxiliary leg as claimed in claim 1 or claim 2, wherein the pivot arm and the auxiliary leg are dimensioned so that, when the auxiliary leg is deployed, the auxiliary leg is in an auxiliary leg latching position.
4. 4. A pivotable telescopic auxiliary leg as claimed in any one of the preceding claims, including a second latch arrangement which is adapted to latch the first and second segments in the retracted state.
5. 5. A pivotable telescopic auxiliary leg as claimed in claim 4, wherein said second latch arrangement latches said pivot arm to a lower one of said segments.
6. 6. A pivotable telescopic auxiliary leg as claimed in any one of the preceding claims, including an auxiliary leg travel limiter arrangement which prevents one or more of the following: the auxiliary leg from being pivoted beyond an auxiliary leg limit angle; the auxiliary leg from being pivoted beyond an auxiliary leg limit angle wherein a first limit angle is greater than an auxiliary leg latching angle.
7. 7. A pivotable telescopic auxiliary leg as claimed in any one of the preceding claims, including a pivot arm travel limiter arrangement adapted to do one or more of the following: limit the angle of deployment of the pivot arm; limit the deployment angle of the pivot arm to an angle greater than a pivot arm latching angle.
8. 8. A pivotable telescopic auxiliary leg as claimed in any one of claims 1 to 7, wherein the first latch arrangement includes a first spring loaded latch element connected to one segment of the auxiliary leg, and adapted to cooperate with corresponding first latch recess means on the other segment.
9. 9. A pivotable telescopic auxiliary leg as claimed in any one of the preceding claims, wherein the first and second segments are one or more of the following: tubular; telescoping;.
10. 10. A pivotable telescopic auxiliary leg as claimed in any one of the preceding claims, wherein the auxiliary leg includes raised longitudinal ribs or beads on the inner wall of an outer segment and or on the outer wall of the inner segment.
11. 11. A pivotable telescopic auxiliary leg as claimed in claim 10, including two or more raised beads.
12. 12. A pivotable telescopic auxiliary leg as claimed in any one of the preceding claims, wherein the cross section of said first and second segments is such that an outer segment and an inner segment are one of the following: circular, or square, or rectangular, or oval.
13. 13. A pivotable telescopic auxiliary leg as claimed in any one of the preceding claims, including an additional locking pin is provided to lock the auxiliary leg in a deployed state.
14. 14. A pivotable telescopic auxiliary leg as claimed in any one of the preceding claims, wherein the first and second segments of the auxiliary leg latch in the deployed state to form a triangle with the pivot arm and the corresponding leg of the ladder.
15. 15. A pivotable telescopic auxiliary leg arrangement as claimed in any one of the preceding claims including a captive releasable latch arrangement adapted to hold the auxiliary leg in the deployed state.
16. 16. A pivotable telescopic auxiliary leg as claimed in any one of the preceding claims including a captive releasable latch arrangement adapted to hold the pivot arm in a retracted state.
17. 17. A pivotable telescopic auxiliary leg as claimed in any one of the preceding claims wherein said pivot arm is a single member.
18. 18. A ladder including one auxiliary leg as claimed in any one of the preceding claims.
19. 19. A ladder as claimed in claim 18, wherein said ladder includes a second auxiliary leg as claimed in any one of claims 1 to 17.
20. 20. A ladder as claimed in claim 18, wherein said first and second auxiliary legs are located at opposed side locations on said ladder.