AU2006202421B2 - A protective arrangement for ladders - Google Patents

Abstract

A protective arrangement for a ladder that is adapted to extend from a first lowered position to a second higher position. The protective arrangement 5 comprising an assembly of members supported relative to the ladder which are adjustable in position so that, in a first position, the members are in a retracted position, and in a second, extended position, the members provide a protective passageway along at least a portion of the length of the ladder, the assembly being further characterised in that a portion of the protective passageway 10 extends to a height which is above a top rung of the ladder when the assembly is in the second, extended position. *

Description

56228 PAB:FKD P/00/01I Regulation 3.2 AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT ORIGINAL Name of Applicant: BOOTH ENGINEERING PTY LTD Actual Inventors: DEVRON BOOTH STUART BOOTH Address for Service: COLLISON & CO., 117 King William Street, Adelaide, S.A. 5000 Invention Title: A PROTECTIVE ARRANGEMENT FOR LADDERS Details of Associated Provisional Application(s): Australian Patent Application No. 2005902938Dated 7 June 2005 The following statement is a full description of this invention, including the best method of performing it known to us: 2 TITLE A protective arrangement for ladders. TECHNICAL FIELD This invention relates to a protective arrangement for ladders. 5 For the purposes of explanation, reference will be made to use of the present invention with respect to motor vehicles and vehicle trailers used to transport liquids or other materials, such as powders, in tanks (tanker trailers), where access to the tank is achieved through uppermost openings, where access thereto is provided by a ladder. It would be understood by those of ordinary skill 10 in the art however that the invention is not limited to use on these tankers, its application could instead extend to use on any fixed ladder. BACKGROUND ART It is conventional that a tanker trailer operator will climb up a ladder and onto the top of the tank and then walk along a walkway along the top of the tank to both 15 open and close tank lids and to otherwise direct pipes into or out of these openings as required. The tanks themselves can be quite a height from road level, so any fall from the ladder or the top of the tank is likely to result in serious injury and possibly even death. Retractable railings have been developed for the walkway atop the tanker, but 20 hitherto no provision has been made to protect the operator when they ascend or descend the ladder and transition from the ladder to the walkway. There are specific difficulties associated with providing a fixed installation providing a surrounding barrier or cage for a ladder. If the cage is on a side or the 3 front of the unit, whether this be a tanker or the like, then such a cage can significantly interfere with access to areas adjacent the ladder. Furthermore, in some cases the ability to provide useful protection is limited if the height of the cage has to be constrained. 5 These problems can be reduced by making a protective structure that is adjustable in position, so that it can be in either an erected or a retracted position. If the retracted position includes an upper most portion which is lowered from the erected position then there can be an answer to the otherwise undue height problem, and this then facilitates an arrangement that assists to provide stability 10 for a person using a ladder. It is therefore an object of the present invention to provide a protective arrangement for a ladder that can be safer for the operator, or at the least provide the public with a useful alternative. Other objects and advantages of the present invention will become apparent from 15 the following description, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed. For the purpose of this specification the word "comprising" means "including but not limited to", and the word 'comprises' has a corresponding meaning. 20 DISCLOSURE OF THE INVENTION In one form of this invention there is proposed a protective arrangement for a ladder that is adapted to extend from a first lowered position to a second higher position, the protective arrangement comprising an assembly of members supported relative to the ladder which are adjustable in position so that, in the 25 first position, the members are in a retracted position, and in the second, 4 extended position, the members provide a protective passageway along at least a portion of the length of the ladder, the assembly being further characterised in that a portion of the protective passageway extends to a height which is above a top rung of the ladder when the assembly is in the second, extended position. 5 Preferably, the ladder and the protective passageway are attached to the rear end of a tanker trailer. 1. Preferably, when in the second position, the protective passageway encloses a region bounded by the assembly of members and the ladder, through which a person using the ladder may pass. 10 Preferably, when in the first position, the assembly of members fold substantially flat against the ladder, closing the protective passageway. Preferably, the assembly of members comprises a support frame that is fixed relative to the end of the tanker trailer and the ladder. Preferably, the protective passageway swings between the first and second 15 positions. Preferably, the protective passageway is driven between the first and second positions by a linear actuator. Preferably, the assembly of members comprises a sub frame that is pivotally attached to the support frame at or toward its uppermost end. 20 Preferably, the sub frame comprises a first portion that is pivotally attached to the support frame, and a second portion that extends from the first portion so as to be perpendicular to it.

5 Preferably, the second portion supports the vertically extending elements of the extended protective passageway. Preferably, the second portion of the sub frame is approximately u-shaped. Preferably, the vertically extending elements are flexible. 5 Preferably, the assembly of members further includes a further approximately u shaped frame that is pivotally attached to the support frame at its ends. Preferably, the further u-shaped frame is suspended from the vertically extending elements when the protective passageway is extended. Preferably, the second portion of the sub frame lies atop the further u-shaped 10 frame when the assembly of members is in the first, retracted position. In a further form, the protective passageway translates between the first and second positions. In a further form, the assembly of members comprises a retractable cage including a cage frame having a substantially upright part or 15 parts, and a substantially horizontally extending part or parts; at least two pairs of oppositely positioned arms, these oppositely positioned arms being positioned such that there are two arms on both sides of the ladder, each of the arms having first and second ends, each arm being pivotally attachable to the support frame at or toward each of their first ends, and pivotally attached to an 20 upright part of the cage frame at or toward their respective second ends, the pivotal attachment points being vertically spaced apart on the support frame and cage frame respectively; 6 and a plurality of bars suspended from the horizontally extending portion of the cage frame such that they can slide relative to it, and means to ensure substantially even spacing of the bars as the protective passageway is opened and closed. 5 Preferably, when in the first, retracted position, the second end of each of the arms are lower than the first and the protective passageway is closed. Preferably, when the second end of each of the arms are at the same approximate height as their first ends, and the protective passageway is opened. Preferably, the horizontally extending portion of the cage frame includes a 10 substantially horizontal rail. Preferably, each of the bars have first and second ends; at their respective first ends, the bars have an eyelet that runs on the rail such that the eyelets are free to slide along this rail. Preferably, each of the arms have a guide for each of the bars, such that these 15 guides are substantially equi spaced along the length of the arm, the guide positionally retaining the bar while remaining free to run along the length of the bar. Preferably, the linear actuator is a pneumatic ram. A further difficulty is experienced in that even though a guard railing arrangement 20 may be provided a top a tank, an operator will not take advantage of this and accordingly will not bother to erect the guard railing when access to the various lids or the walkway is required. An advantage of the present invention then is that when the assembly of members is retracted, the protective passageway is closed, and it limits climbing access to the ladder.

7 In preference then there is provided a manually operable control means that is positioned in the adjacent vicinity of the ladder that would be used to simultaneously extend the protective passageway and the walkway railing substantially simultaneously. 5 In a further form, the manually operable control means would extend the walkway railing before extending the protective passageway. BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of this invention it will now be described with respect to the preferred embodiment, which shall be described herein with the assistance 10 of drawings wherein; Figure 1 is a perspective view of a tanker trailer equipped with a retractable protective passageway; Figures 2, 3 and 4 are side views of the tanker trailer in Figure 1, illustrating the protective passageway transitioning between the first and second positions 15 relative to the ladder; Figure 5 is a perspective view of a tanker trailer equipped with a retractable protective passageway assembly and a retractable walkway railing, illustrating both in their extended positions; Figure 6 is a perspective view of the tanker trailer in Figure 1, illustrating both the 20 protective passageway assembly and the retractable walkway railing in their retracted positions; 8 Figures 7 and 8 are side views of the tanker trailer in Figure 1, illustrating both the protective passageway assembly and the retractable walkway railing in their extended positions; Figure 9 is a detailed view of some of the bars suspended from the horizontally 5 extending portion of the protective passageway, and of the means to ensure substantially even spacing of the bars as the protective passageway is opened and closed; and Figure 10 is a rear end view of the tanker trailer in Figure 1, illustrating both the retractable protective passageway assembly and the retractable railing in their 10 extended positions. DETAILED DESCRIPTION OF THE INVENTION Referring now to Figure 1, where there is illustrated a rearward end of a tanker trailer 1 of the conventional style, having a tank 2, which has a generally circularly shaped cross section along its length. 15 The tank 2 has a plurality of openings along its top, which are capped by lids, and a walkway that is defined by a retractable safety railing 4 (not shown in Figures 1 through 4, but shown in Figures 6 through 10) that extends down both sides of the walkway and across the end of the walkway at the forward end of the tank. Access to the walkway is achieved by climbing a ladder 6, which in this case is 20 located at the rear end of the tank 1. This ladder is surrounded by a retractable protective arrangement 10 comprising an assembly of members that define a protective passage way that, when extended (as illustrated in Figure 1), extends to a height greater than both the walkway and the top rung of the ladder 6. This ensures that the operator is surrounded by guarding as they transition from the 25 ladder to the walkway atop the tanker.

9 The retractable protective arrangement 10 includes a support frame 11 that, like the ladder 6, is fixed to the tank 2. The assembly of members comprises a sub frame 12 that is pivotally attached to the support frame 11 at or toward its uppermost end. 5 This sub frame 12 comprises a first portion 14 that is pivotally attached to the support frame, and a second portion 16 that extends from the first portion 14 so as to be perpendicular to it. The second portion 16 supports the vertically extending elements 18 of the extended protective passageway. The second portion 16 of the sub frame 12 is approximately u-shaped. A first 10 portion 14 of the sub frame extends from each of the ends of this u-shaped portion 16. The other ends of the respective first portions 14 pivotally attach to the support frame 11 on either side of the walkway. The vertically extending elements 18, form part of a net of seatbelt webbing, which was chosen for this application because of its strength and flexibility. A 15 plurality of these vertically extending elements 18 are attached to the sub frame 12 at equispaced positions around its u-shaped portion. The assembly of members further includes a further two, approximately u-shaped frames 20, that are pivotally attached to the support frame 11 at their ends. The approximately u-shaped frames 20 are pivotally attached to the support frame 11 20 so as to be equispaced relative to one another and the sub frame 12. The further u-shaped frames 20 are connected to the vertically extending elements 18 so that they are suspended from the webbing when the protective passageway is extended.

10 This webbing fills the gaps that would otherwise exist between the frames 12 and 20 when the protective passageway is erected. When the retractable passageway is in the first, retracted position as illustrated in Figure 2, the second portion 16 of the sub frame 12 lies approximately vertically, 5 atop the further u-shaped frames 20. A linear actuator 22 extends between the support frame 11 and a first portion 14 of the sub frame 12. When the linear actuator 22 is activated, it swings the first portion 14 of the sub frame 12 from its approximately horizontal orientation, into an approximately vertical one. As it does so, the second portion 16 brings with it 10 the vertically extending members 18, which in turn bring with them the two further u-shaped frames 20, until the protective passageway hits it position stops and is erected (see Figures 1 and 4). Once the protective passageway has been retracted, a small gas strut 24 retains the assembly of members in this position for transportation. 15 Referring now to Figures 5 through 10, there is a protective passageway comprising a cage frame 116 having a substantially upright portion 118 and a substantially horizontally extending portion 120. There are two pairs of opposing arms 122 and 124 connecting the cage frame 116 to the support frame 111. These opposing pairs of arms 122 and 124 are 20 positioned such that there are two arms on either side of the ladder 106, each of the arms having first a and second b ends. The arms are pivotally attached to the support frame 111 at their respective first ends a, and pivotally attached to the upright portion 118 of the cage frame 116 at their respective second ends b. The pivotal attachment points for the two pairs of arms are vertically spaced apart on 25 the support frame 111 and cage frame 16 respectively.

11 There is a linear actuator, in this case a pneumatic ram 130, having first 130a and second 130b ends. The first end 130a of the ram is pivotally connected to the tanker trailer 100, and the second end 130b is pivotally connected to one of the lower arms 122. 5 In use, the pneumatic ram 130 drives the opposing arms 122 and 124 from a first, lowered position, in which the second end of each of the arms b are lower than the first a (as illustrated in Figure 6), and the protective passageway is closed, to a second raised position in which the second end b of each of the arms are at the same approximate height as the first end a (as illustrated in Figure 5), 10 and the protective passageway is opened. The horizontally extending portion of the cage frame supports a substantially horizontal rail 140. A plurality of bars 142 are suspended from the horizontal rail by eyelets 144 attached to the uppermost end of each of the bars 142, so that the ends of the respective bars can slide along the rail 140. 15 Without these bars 140, a very large gap would remain between the cage frame and each of the first 122 and second 124 arms when the protective passageway is open, a gap that is potentially large enough for a person to fall through. Each of the bars 142 runs through an eyelet 146 that is pivotally connected to each of the first 122 and second 124 sets of arms. There is one eyelet 46 per bar 20 142, per arm, and these eyelets 146 are substantially equi-spaced along the length of the arm. These eyelets maintain even spacing between the bars 142 at the respective levels of the first and second sets of arms. Even spacing between each pair of adjacently positioned bars 142 is maintained at their uppermost ends throughout each of the extension and retraction 25 operations, by a pair of elongate linkage elements 150 that pass between each 12 pair of adjacent bars 142. Each pair of elongate linkage elements is pivotally connected together proximate to their respective midpoints. A first pair of elongate linkage elements 150a connects a first bar 142a to a portion of the cage frame. A first linkage 152 element has a first end 152a 5 pivotally connected to a portion 148 of the cage frame such that this pivotal connection point is fixed in position relative to the cage frame. The second linkage element 154 has an eyelet at a first end 154a, and this eyelet is free to slide along a substantially vertical portion of the cage frame 148. Each of the first 152a and second linkage 154a elements is then pivotally connected to the other 10 proximate to their respective midpoints. The second end 152b of the first linkage element 152 is pivotally connected to an eyelet 156 that can run along the first bar 142a in a substantially vertical direction. The second end 154b of the second linkage element 154 is pivotally connected to an eyelet 158 that can run in a substantially horizontal direction 15 along the rail 140. Just as this first pair of elongate linkage elements 150a connects the first bar 142a to a portion of the cage frame, a second pair of elongate linkage elements 150b connects a second bar 142b to the first bar 142a in almost exactly the same fashion. 20 In the retracted position then, the second end of each of the arms b is lower than the first, and the horizontal distance between the eyelets positioned along the length of each of the arms is small, so that the bars then are very close together when the protective passageway is closed. As the pneumatic ram is extended, the second ends of the first set of arms are 25 raised, and the second set of arms are raised also by virtue of their connection to the first set via the vertical portion of the cage frame. As the two sets of arms are 13 raised the horizontal distance between the eyelets positioned along the length of each of the arms increases, and the distance between adjacent pairs of bars increases until the ram is fully extended and the protective passageway is open. As the distance between adjacent pairs of bars increases, the pairs of linkage 5 elements that connects one bar to the next open in a scissoring fashion so as to control the spacing between the bars at their respective upper ends, and then maintain even spacing between adjacent bars during retraction. It is considered that the protective arrangement for ladders according to the present invention would be of particular use to those who must work upon 10 elevated platforms, such as atop tankers. Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognised that departures can be made within the scope of the invention, which is not to be limited to the details described herein but is to be accorded the full scope of the 15 appended claims so as to embrace any and all equivalent devices and apparatus.

Claims (22)

1. A protective arrangement for a ladder that is adapted to be attached to the rear end of a tanker trailer, the protective arrangement extends from a first lowered position to a second higher position, the protective arrangement comprising an assembly of members supported relative to the ladder which are adjustable in position so that, in the first position, the members are in a retracted position, and in the second extended position, the members provide are protective passageway along a least a portion of the, length of the ladder, the assembly being further characterized in that a portion of the protective passageway extends to a height which is above a top rung of the ladder when the assembly is in the second extended position.

2. The protective arrangement as in claim 1 further characterized in that, when in the second position, the protective passageway encloses a region bounded by the assembly of members and the ladder, through which a person using the ladder may pass.

3. The protective arrangement as in either claims 1 or 2 further characterized in that, when in the first, retracted position, the assembly of members fold substantially flat against the ladder, closing the protective passageway and bars access to both the ladder and the walkway.

4. The protective arrangement as in claims 1 to 3 further characterized in that the assembly of members comprises a support frame that is fixed relative to the end of the tanker trailer and the ladder.

5. The protective arrangement as in claims 1 to 4 further characterized in that the protective passageway swings between the first and second positions. 15

6. The protective arrangement as in claim 5 further characterized in that the assembly of members comprises a sub frame that is pivotally attached to the support frame at or toward the uppermost end of the support frame.

7. The protective arrangement as in claim 6 further characterized in that the sub frame comprises a first portion that is pivotally attached to the support frame, and a second portion that extends from the first portion so as to be perpendicular to it.

8. The protective arrangement as in claim 7, further characterized in that the second portion of the sub frame is approximately u-shaped.

9. The protective arrangement as in claims 7 or 8, further characterized in that the second portion supports vertically extending elements of the extended protective passageway.

10. The protective arrangement as in claim 9 further characterized in that the vertically extending elements are flexible.

11. The protective arrangement as in claims 1 to 10 further characterized in that the assembly of members further includes a further approximately u shaped frame that is pivotally attached to the support frame at or toward the ends of the u-shaped frame.

12. The protective arrangement as in claims 1 to 11 further characterized in that the further u-shaped frame is suspended from the vertically elements when the protective passageway is extended.

13. The protective arrangement as in claims 1 to 12 further characterized in that the second portion of the sub frame lays atop the further u-shaped frame when the assembly of members is in the first retracted position. 16

14. The protective arrangement as in claims 1 to 13 further characterized in that the protective passageway is movable between the first and second positions.

15. The protective arrangement as in claims 1 to 14 further characterized in that the assembly of members comprises: a retractable cage including a cage frame having substantially upright part or parts, and a substantially horizontally extending part or parts; at least two pairs of oppositely positioned arms, these oppositely positioned arms being positioned such that there are two arms on both sides of the ladder, each of the arms having first and second ends, each arm being pivotally attachable to the support frame at or toward each of their first ends, and pivotally attached to an upright part of the cage frame at or toward their respective second ends, the pivotal attachment points being vertically spaced apart on the support frame and cage frame respectively; and a plurality of bars suspended from the horizontally extending portion of the cage frame such that they can slide relative to it, and means to ensure substantially even spacing of the bars as the protective passageway is opened and closed.

16. The protective arrangement as in claims 1 to 15 further characterized in that when in the first retracted position, the second end of each of the arms are lower than the first and the protective passageway is closed.

17. The protective arrangement as in claim 16 further characterized in that when the second end of each of the arms are at the same approximate height as their first ends, and the protective passageway is opened. 17

18. The protective arrangement as in claims 15 to 17 further characterized in that the horizontally extending portion of the cage frame includes a substantially horizontal rail.

19. The protective arrangement as in claims 15 to 18 further characterized in that each of the bars have first and second ends; at their respective first ends, the bars have an eyelet that runs on the rail such that the eyelets are free to slide along this rail.

20. The protective arrangement as in claims 15 to 19 further characterized in that each of the arms have a guide for each of the bars, such that these guides are substantially equi spaced along the length of the arm, the guide positionally retaining the bar while remaining free to run along the length of the bar.

21. The protective arrangement as in claims 1 to 20 further characterized in that the protective passageway is driven between the first and second positions by a linear actuator.

22. A protective arrangement substantially as described in the specification with reference to and as illustrated in the accompanying drawings.