CA1094028A - Ladders - Google Patents
LaddersInfo
- Publication number
- CA1094028A CA1094028A CA306,203A CA306203A CA1094028A CA 1094028 A CA1094028 A CA 1094028A CA 306203 A CA306203 A CA 306203A CA 1094028 A CA1094028 A CA 1094028A
- Authority
- CA
- Canada
- Prior art keywords
- hollow
- section
- stile
- ladder
- steel
- 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
Links
Classifications
-
- E—FIXED CONSTRUCTIONS
- E06—DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
- E06C—LADDERS
- E06C7/00—Component parts, supporting parts, or accessories
- E06C7/08—Special construction of longitudinal members, or rungs or other treads
- E06C7/082—Connections between rungs or treads and longitudinal members
- E06C7/085—Connections between rungs or treads and longitudinal members achieved by deforming the rung or the stile
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Ladders (AREA)
Abstract
ABSTRACT
"Improvements in or relating to ladders"
A component for a ladder which comprises a thin hollow section of metallic material filled with a synthetic plastics material foam, such as polyurethane foam, with the section preferably made out of thin sheet steel with a coating of plastics material thereon. There is also provided a ladder, especially an extension ladder, compri-sing one or more such components.
"Improvements in or relating to ladders"
A component for a ladder which comprises a thin hollow section of metallic material filled with a synthetic plastics material foam, such as polyurethane foam, with the section preferably made out of thin sheet steel with a coating of plastics material thereon. There is also provided a ladder, especially an extension ladder, compri-sing one or more such components.
Description
1~ 40Z~
The present invention relates to stiles and other components of ladders, as well as to ladders, especially extension ladders.
As is well known, aluminium has become very expensive and alterna-tive materials, particularly for extension ladders, are urgently being sought.
According to an aspect of the invention, there is provided a stile for a ladder, extension ladder, steps or the like, said stile comprising a hollow box section, the hollow box section comprising two interlocked elongate sections of steel of a thickness in the range of from 0.5 to 0.8 mm, said elongate sections being interlocked by having been longitudinally slid one in-side the other, and the hollow being filled with a synthetic plastics materialfoam. The steel may be coated with plastic material.
According to another aspect of the invention, there is provided an extension ladder component which comprises two stiles, each stile comprising a hollow box section, each hollow section comprising two interlocked elongate sections of steel of a thickness in the range of from 0.5 to 0.8 mm, said two elongate sections being interlocked by having been longitudinally slid one in-side the other, and the hollow being filled with a synthetic foam plastic material.
According to a further aspect of the invention, there is provided an extension ladder which comprises two components, each component comprising two stiles and a multiplicity of rungs, each stile comprising a hollow box section, the hollow section comprising two interlocked elongate sections of steel of a thickness in the range of from D.5 to 0.8 mm coated with polyvinyl chloride, said elongate sections being interlocked by having been slid one inside the other and the hollow being filled with polyurethane foam. The rungs may be locked to a respective one section of each hollow section, so that the end of each rung is within the respective stile and capped prior to the infill of foam into the stiles.
The term "ladder" as used herein is a generic term that includes extension ladders, ladders, steps and the - lA -. . ., ~
--~ 1094028 _ 2 -like.
Whilst there are obviously many ways of forming a hollow section, the hollow section is preferably formed from two separate sections which, when slid together, form the hollow section. The two separate sections are prefer-ably made of very thin steel (generPlly having a wall thickness in the range of from 0.5 to 0.8 m~ when using the steel). Of course, the section could be made of aluminium but the wall thickness will naturally be greater than the corresponding necessary thickness for steel.
The formed hollow section will have good strength in pure bending about either the X-X or Y-Y axes~ the strength naturally being dependent on the size of section~
wall thic~ness of the material and the material itself.
However~ such a hollow section will have little or no ~torsional rigidity~ because both sections are "open" sec-tions.
To obtain good torsional rigidity, it has been found pos~ible to restrain each face of the section from moving relative to the other face by filling the section with a synthetic pla~tics material foam~ especially a low density polyurethane foam. Whilst one could use a foam other than a low density foam~ this is not advantageous from a cost or weight point of view. The filling of the section serves not only the purpose of giving good torsional rigi-dit~ to the section but it also stiffens the thin walls of the section.
Normally, the sections when made of steel will be made of very thin wall strip steel coated with P.V.C. Of course 9 the steel will normally be treated against rusting prior to coating with P.V.C.
The forming of the hollow by using two sect~ons is preferred for two basic reasons, namely to allow t~e use of P.V.~. coated steel or similar material that cannot b~
3~ welded into a hollow section and to allow the rungs of the ladder to b8 fitted with no external protrusions.
The basic advantages of a ladder, particularly appli-.. _ .. . .. .. _ .. . .. . . . . .
cable to extension ladders, with stiles made of foam filledsteel or similar thin walled material is that, especially when a low density polyurethane foam is used, the ladder is considerably lighter than an equivalent wooden ladder~
it is very little heavier than an equivalent aluminium ladder, it is very much cheaper, at least at the present time~ than an equivalent aluminium ladder and the price is comparable, at least at the present time, with an equiva-lent wooden ladder.
The preferred low density polyurethane foam has a density of about 3 lb. per cubic foot.
For a better underst~nding of the present invention and to show how the same may be carried into effect, ref-erence will now be made, by way of example, to the accom-panying drawings, in whichs-Figure 1 shows a perspective view of part of an assem-bled extension ladder, and Figure 2 shows a series of plan/sectional views showing how a tread is fastened to stiles.
~igure 1 of the drawings shows stiles 1 made up of sections 2 and 3, connected by treads 4, with the stiles being filled with foam 5.
Referring now to Figure 2 of the drawings, an alumin-ium section of ribbed tube 6, preferably of generally cir-cular cross-section, has two ribs 7 formed thereabout, in the aluminium, spaced at the distance apart that the stiles are to be positioned, which strengthened tube is to form a rung or tread for the exten~ion ladder. Two inner hollow section members 2 with appropriately dimensioned holes therein have the ends of the requisite number of treads inserted therein and then an additional rib 8 is formed at each end of each tread, so that each tread is securely fastened to each inner hollow section member 2. Caps (not shown) of steel for cxample are then gener~ ly f;tted to the en~s of the tube 6 to prevent ingress of foam there-into in the later stages of manufacture (for economy of foam). A second hollow section member 3 is then slid ~940Z8 onto each of the hollow section members 2 having treads 6 fastened thereto and the formed hollow section is then filled with low density polyurethane foam which is allowed to cure therein. The end product is an extension ladder section. The hollow section members 2 and 3 are advanta-geously made of P.V.C. coated steel of thickness ~n the range of from 0.5 to 0.8 mm.
The tube 6 forming the tread can of course be any convenient shape~ for exsmple of "D" shape or be rectangu-lar in cros~ section.
Of course, the present invention could be used in the manufacture of ladders other than e2tension ladders~ if so desired.
The present invention relates to stiles and other components of ladders, as well as to ladders, especially extension ladders.
As is well known, aluminium has become very expensive and alterna-tive materials, particularly for extension ladders, are urgently being sought.
According to an aspect of the invention, there is provided a stile for a ladder, extension ladder, steps or the like, said stile comprising a hollow box section, the hollow box section comprising two interlocked elongate sections of steel of a thickness in the range of from 0.5 to 0.8 mm, said elongate sections being interlocked by having been longitudinally slid one in-side the other, and the hollow being filled with a synthetic plastics materialfoam. The steel may be coated with plastic material.
According to another aspect of the invention, there is provided an extension ladder component which comprises two stiles, each stile comprising a hollow box section, each hollow section comprising two interlocked elongate sections of steel of a thickness in the range of from 0.5 to 0.8 mm, said two elongate sections being interlocked by having been longitudinally slid one in-side the other, and the hollow being filled with a synthetic foam plastic material.
According to a further aspect of the invention, there is provided an extension ladder which comprises two components, each component comprising two stiles and a multiplicity of rungs, each stile comprising a hollow box section, the hollow section comprising two interlocked elongate sections of steel of a thickness in the range of from D.5 to 0.8 mm coated with polyvinyl chloride, said elongate sections being interlocked by having been slid one inside the other and the hollow being filled with polyurethane foam. The rungs may be locked to a respective one section of each hollow section, so that the end of each rung is within the respective stile and capped prior to the infill of foam into the stiles.
The term "ladder" as used herein is a generic term that includes extension ladders, ladders, steps and the - lA -. . ., ~
--~ 1094028 _ 2 -like.
Whilst there are obviously many ways of forming a hollow section, the hollow section is preferably formed from two separate sections which, when slid together, form the hollow section. The two separate sections are prefer-ably made of very thin steel (generPlly having a wall thickness in the range of from 0.5 to 0.8 m~ when using the steel). Of course, the section could be made of aluminium but the wall thickness will naturally be greater than the corresponding necessary thickness for steel.
The formed hollow section will have good strength in pure bending about either the X-X or Y-Y axes~ the strength naturally being dependent on the size of section~
wall thic~ness of the material and the material itself.
However~ such a hollow section will have little or no ~torsional rigidity~ because both sections are "open" sec-tions.
To obtain good torsional rigidity, it has been found pos~ible to restrain each face of the section from moving relative to the other face by filling the section with a synthetic pla~tics material foam~ especially a low density polyurethane foam. Whilst one could use a foam other than a low density foam~ this is not advantageous from a cost or weight point of view. The filling of the section serves not only the purpose of giving good torsional rigi-dit~ to the section but it also stiffens the thin walls of the section.
Normally, the sections when made of steel will be made of very thin wall strip steel coated with P.V.C. Of course 9 the steel will normally be treated against rusting prior to coating with P.V.C.
The forming of the hollow by using two sect~ons is preferred for two basic reasons, namely to allow t~e use of P.V.~. coated steel or similar material that cannot b~
3~ welded into a hollow section and to allow the rungs of the ladder to b8 fitted with no external protrusions.
The basic advantages of a ladder, particularly appli-.. _ .. . .. .. _ .. . .. . . . . .
cable to extension ladders, with stiles made of foam filledsteel or similar thin walled material is that, especially when a low density polyurethane foam is used, the ladder is considerably lighter than an equivalent wooden ladder~
it is very little heavier than an equivalent aluminium ladder, it is very much cheaper, at least at the present time~ than an equivalent aluminium ladder and the price is comparable, at least at the present time, with an equiva-lent wooden ladder.
The preferred low density polyurethane foam has a density of about 3 lb. per cubic foot.
For a better underst~nding of the present invention and to show how the same may be carried into effect, ref-erence will now be made, by way of example, to the accom-panying drawings, in whichs-Figure 1 shows a perspective view of part of an assem-bled extension ladder, and Figure 2 shows a series of plan/sectional views showing how a tread is fastened to stiles.
~igure 1 of the drawings shows stiles 1 made up of sections 2 and 3, connected by treads 4, with the stiles being filled with foam 5.
Referring now to Figure 2 of the drawings, an alumin-ium section of ribbed tube 6, preferably of generally cir-cular cross-section, has two ribs 7 formed thereabout, in the aluminium, spaced at the distance apart that the stiles are to be positioned, which strengthened tube is to form a rung or tread for the exten~ion ladder. Two inner hollow section members 2 with appropriately dimensioned holes therein have the ends of the requisite number of treads inserted therein and then an additional rib 8 is formed at each end of each tread, so that each tread is securely fastened to each inner hollow section member 2. Caps (not shown) of steel for cxample are then gener~ ly f;tted to the en~s of the tube 6 to prevent ingress of foam there-into in the later stages of manufacture (for economy of foam). A second hollow section member 3 is then slid ~940Z8 onto each of the hollow section members 2 having treads 6 fastened thereto and the formed hollow section is then filled with low density polyurethane foam which is allowed to cure therein. The end product is an extension ladder section. The hollow section members 2 and 3 are advanta-geously made of P.V.C. coated steel of thickness ~n the range of from 0.5 to 0.8 mm.
The tube 6 forming the tread can of course be any convenient shape~ for exsmple of "D" shape or be rectangu-lar in cros~ section.
Of course, the present invention could be used in the manufacture of ladders other than e2tension ladders~ if so desired.
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A stile for a ladder, extension ladder, steps or the like, said stile comprising a hollow box section, the hollow box section comprising two interlocked elongate sections of steel of a thickness in the range of from 0.5 to 0.8 mm, said elongate sections being interlocked by having been longitudin-ally slid one inside the other, and the hollow being filled with a synthetic plastics material foam.
2. A stile according to claim 1, wherein the steel is coated with plas-tic material.
3. A ladder, extension ladder, steps or the like, which comprises one or more stile(s) in accordance with claim 1 or 2.
4. An extension ladder component which comprises two stiles, each stile comprising a hollow box section, each hollow section comprising two inter-locked elongate sections of steel of a thickness in the range of from 0.5 to 0.8 mm, said two elongate sections being interlocked by having been longitud-inally slid one inside the other, and the hollow being filled with a synthetic foam plastic material.
5. An extension ladder which comprises two components, each component comprising two stiles and a multiplicity of rungs, each stile comprising a hollow box section, the hollow section comprising two interlocked elongate sections of steel of a thickness in the range of from 0.5 to 0.8 mm coated with polyvinyl chloride, said elongate sections being interlocked by having been slid one inside the other and the hollow being filled with polyurethane foam.
6. An extension ladder according to Claim 5, wherein the rungs are locked to a respective one section of each hollow section, so that the end of each rung is within the respective stile and capped prior to the infill of foam into the stiles.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB28283/77 | 1977-07-06 | ||
| GB28283/77A GB1595202A (en) | 1977-07-06 | 1977-07-06 | Ladders |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1094028A true CA1094028A (en) | 1981-01-20 |
Family
ID=10273200
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA306,203A Expired CA1094028A (en) | 1977-07-06 | 1978-06-26 | Ladders |
Country Status (14)
| Country | Link |
|---|---|
| EP (1) | EP0000344B1 (en) |
| JP (1) | JPS5418362A (en) |
| AR (1) | AR219759A1 (en) |
| AU (1) | AU3774078A (en) |
| BR (1) | BR7804218A (en) |
| CA (1) | CA1094028A (en) |
| DE (1) | DE2860615D1 (en) |
| DK (1) | DK305678A (en) |
| ES (1) | ES471508A1 (en) |
| FI (1) | FI782172A (en) |
| GB (1) | GB1595202A (en) |
| IT (2) | IT7853480V0 (en) |
| NO (1) | NO782223L (en) |
| ZA (1) | ZA783722B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7453025B2 (en) | 2004-09-22 | 2008-11-18 | Arborgen, Llc | Reproductive ablation constructs |
| FR3024489B1 (en) * | 2014-07-29 | 2018-08-10 | Gimaex International | TELESCOPIC SCALE COMPRISING SCALE TRONCONS OF DIFFERENT DENSITY |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2855134A (en) * | 1956-10-04 | 1958-10-07 | Bauer Mfg Company | Metal ladder |
| GB923788A (en) * | 1960-10-18 | 1963-04-18 | C F Taylor Plastics Ltd | Improvements in or relating to joining a main tube to a secondary tube laterally fitted thereto |
| BE760720A (en) * | 1970-12-22 | 1971-05-27 | Loix Gilbert | PREFABRICATED METAL STAIRCASE. |
-
1977
- 1977-07-06 GB GB28283/77A patent/GB1595202A/en not_active Expired
-
1978
- 1978-06-26 CA CA306,203A patent/CA1094028A/en not_active Expired
- 1978-06-27 EP EP78100247A patent/EP0000344B1/en not_active Expired
- 1978-06-27 NO NO782223A patent/NO782223L/en unknown
- 1978-06-27 DE DE7878100247T patent/DE2860615D1/en not_active Expired
- 1978-06-28 ZA ZA00783722A patent/ZA783722B/en unknown
- 1978-06-30 BR BR7804218A patent/BR7804218A/en unknown
- 1978-07-04 AU AU37740/78A patent/AU3774078A/en active Pending
- 1978-07-05 IT IT7853480U patent/IT7853480V0/en unknown
- 1978-07-05 FI FI782172A patent/FI782172A/en not_active Application Discontinuation
- 1978-07-05 IT IT7868578A patent/IT1172892B/en active
- 1978-07-05 JP JP8182478A patent/JPS5418362A/en active Pending
- 1978-07-06 ES ES471508A patent/ES471508A1/en not_active Expired
- 1978-07-06 DK DK783056A patent/DK305678A/en unknown
- 1978-07-06 AR AR272863A patent/AR219759A1/en active
Also Published As
| Publication number | Publication date |
|---|---|
| FI782172A (en) | 1979-01-07 |
| IT7868578A0 (en) | 1978-07-05 |
| IT1172892B (en) | 1987-06-18 |
| ES471508A1 (en) | 1979-02-01 |
| NO782223L (en) | 1979-01-09 |
| JPS5418362A (en) | 1979-02-10 |
| DK305678A (en) | 1979-01-07 |
| IT7853480V0 (en) | 1978-07-05 |
| DE2860615D1 (en) | 1981-05-07 |
| BR7804218A (en) | 1979-04-17 |
| AR219759A1 (en) | 1980-09-15 |
| ZA783722B (en) | 1979-06-27 |
| GB1595202A (en) | 1981-08-12 |
| EP0000344A1 (en) | 1979-01-24 |
| EP0000344B1 (en) | 1981-04-15 |
| AU3774078A (en) | 1980-01-10 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |