US2788167A - Molded ladder - Google Patents

Molded ladder Download PDF

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Publication number
US2788167A
US2788167A US367710A US36771053A US2788167A US 2788167 A US2788167 A US 2788167A US 367710 A US367710 A US 367710A US 36771053 A US36771053 A US 36771053A US 2788167 A US2788167 A US 2788167A
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Prior art keywords
ladder
side pieces
sides
pieces
sections
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Expired - Lifetime
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US367710A
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Harold E Morrison
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D R MCNEILL JR
G B HAYNES
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D R MCNEILL JR
G B HAYNES
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Priority to US367710A priority Critical patent/US2788167A/en
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    • 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
    • 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

  • This invention relates to ladders and has for its main object the provision of a ladder that is very light in weight, yet strong and rigid, and which ladder is molded or cast from electrical insulation material.
  • Another object of the invention is the provision of a ladder adapted to be formed in a single molding operation from a composition material such as fiberglass and a suitable binder, and which ladder is so designed as to provide the maximum strength and maximum lightness in weight.
  • a still further object is the provision of an extension ladder that is very strong, light in weight and in which the sections forming such ladder are substantially of the same structure and so constructed and assembled that one ladder section guides the other during extension or retraction of one section relative to the other.
  • the present structure provides a ladder that is capable of being formed in one molding step, and the parts of the ladder are so designed as to not only enable said molding operation, but to give maximum strength where required, together with minimum material for such strength.
  • the finished ladder is an excellent non-condoctor of electricity, it is particularly suitable for linemen and for others that may find occasion to use the ladder where it would be dangerous to use ladders of other material.
  • Fig. 1 is a fragmentary perspective view of a ladder made in accordance with this invention and showing the structure that contributes to the employment of the structure in making an extension ladder.
  • Fig. 2 is an enlarged sectional view taken along line 2-2 of Fig. 1.
  • Fig. 3 is an enlarged sectional view taken along line 3-3 of Fig. 1.
  • each side piece of the ladder is generally designated 1, 2, and the rungs are designated 3.
  • the side pieces and rungs are formed integrally in one piece, and each side piece comprises a vertically elongated channel member having sides 4, 5, and a curved bottom wall 6 (Fig. 2
  • the remaining side is open and may be called the rear side since it would face away from the user when the ladder is in use.
  • the sides 4, extend divergently relative to each other from bottom wall 6, and their inner surfaces 7 are preferably flat.
  • the sides 4, 5 are progressively increasing in thickness along their free edges, as best seen at 8 in Fig. 2, which increased thickness along said edges serves to strength the side pieces. Otherwise the thickness of the material forming said sides is of uniform thickness, preferably of about one quarter of an inch, but this inice 2 vention is not restricted to such thickness for the ladder may be made of any dimensions found most desirable for the jobs to be done.
  • Each of the rungs 3 is also a channel member. Said rungs have laterally opening sides that are directed in the same direction as the open sides of the vertically extending side pieces 1, 2 when the latter are vertical.
  • each rung slants slightly upwardly in a rearward direction (the rear side being the open side that is directed away from the user) and said side 10 'is of progressively increasing thickness in said rearward direction.
  • each rung extends divergently relative to side 10 in a rearward direction and bottom wall 12 is curved transversely of the length of each rung and integrally joins sides 10, 11.
  • each rung curves downwardly (in a rearward direction) rather steeply from a point spaced slightly rearwardly of bottom wall 12, thus producing a generally vertically extending marginal portion 13 along the open side of each rung, which marginal portion acts like a truss for supporting weight in said rung.
  • the rungs 3 extend between the opposed sides 5 of side pieces 1, 2 and positioned between the sides 4, 5 of each side piece at each end of each rung is a web 15 (Fig. 2)
  • rungs 3 spaced along rungs 3 and between upper and lower sides 10, 11 of each rung are webs 16 integrally connecting said sides thus stifliening the rungs (Fig. 3).
  • the webs 15 that are between the sides 4, 5 of the side pieces 1, 2 are curved along their rearwardly directed free edges at the open sides of said side pieces, and as these webs are horizontal (when the side pieces are vertically extending), their curved rear edges extend horizontally. Said curved rear edges of the webs 15 substantially correspond to the horizontal cross sectional contour of the outer side of the bottom wall 6 of each side piece.
  • the upper section 20 (Fig. 1) and the lower section 21, have paralleLside pieces of the same spacing and are positioned so that the curved bottom wall 6 of the side pieces of the section extend be tween the walls 4, 5 of the side pieces of the other section and against the curved edges 17 of webs 15 thus said webs form guides slidably supporting the side pieces of one of the two sections. If it were not for said webs, the side pieces would jam one within the other, but with this structure they readily slide relative to each other.
  • the conventional straps 25 (only two are shown, there usually being another set spaced from these along the ladders) hold the ladder sections together.
  • the usual supports in extension ladders (not shown) at the lower end of the upper one, serve to hold the upper ladder in extended position. No claim is made to such supports since they are old and are readily adapted to the present ladders.
  • the ladder can be readily molded in one piece, but the structure that contributes to that result also contributes to strengthening the ladder and bracing the side pieces and rungs against any tendency to twist or to bend when the ladder is in use.
  • a ladder having elongated generally vertically extending side pieces disposed in a common plane in side by side horizontally spaced relation, vertically spaced rungs extending between and connecting said side pieces, said rungs being in the form of horizontally extending channel members having an upper side wall and a lower side wall and a bottom wall connecting them along one of their longitudinally extending edges and the sides of said rungs opposite. their. bottom walls being open and generally directed perpendicular to said plane, the lower side Wall of each rung being curved downwardly in cross sectional contour transversely of each rung and the upper side Wall of each rung. having a substantially flat upper side extending slightly upwardly relative toa horizontal plane in direction toward its free edge when said side pieces are vertical.
  • An extension ladder comprising apair of ladder sections each having. a pair of elongated parallel side pieces equally spaced apart and with the side pieces of one section aligned with those of the other section in direction transversely of said sections, each of said side pieces being in the form of a channel having generally opposed side Walls and a bottom wall? connecting them along one of their free edges with their side opposite said bottom wall being. open, the bottom walls of theside pieces of one pair extending into the. open sides of the Side pieces of the other. pair, and means within the. said.
  • An extension ladder comprising a pair of ladder sections each having a pair of elongated parallel side pieces equally spaced apart and with the side pieces of one section aligned with those of the other section in direction transversely of said sections, each of said side pieces being in the form of a channel having generally opposed side walls and a bottom wall connecting them alongone of their free edges with their side opposite said bottom wall being open, the bottom. walls of the side pieces of one pair extending into the open sides of the side pieces of the other pair, and means within the said side pieces of said other pair slidably engaging the said bottom Walls that extend into said open sides for sliding one of said ladder sections longitudinally thereof relative to the other and means connecting said sections for holding them together during such sliding,'saidmeans within. said side pieces being webs connecting the side walls of said last mentioned side pieces reinforcing the latter, the open sides of the side pieces of said sections. being directed laterally of the plane in which the side pieces of each section are disposed.

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

Description

April 9, 1957 H. E. MORRISON MOLDED LADDER Filed July 1:5, 1953 &
' INVENTOR. v Harald-E Huff/500..-
United States Patent MOLDED LADDER Harold E. Morrison, San Francisco, Calif., assignor of one-third to G. B. Haynes, Los Altos, and one-third to D. R. McNeill, In, San Francisco, Calif.
Application July 13, 1953, Serial No. 367,710
3 Claims. (Cl. 228-18) This invention relates to ladders and has for its main object the provision of a ladder that is very light in weight, yet strong and rigid, and which ladder is molded or cast from electrical insulation material.
Another object of the invention is the provision of a ladder adapted to be formed in a single molding operation from a composition material such as fiberglass and a suitable binder, and which ladder is so designed as to provide the maximum strength and maximum lightness in weight.
A still further object is the provision of an extension ladder that is very strong, light in weight and in which the sections forming such ladder are substantially of the same structure and so constructed and assembled that one ladder section guides the other during extension or retraction of one section relative to the other.
The use of fiberglass and a plastic is not new in itself. Automobile bodies, furniture, and other articles have been molded from such material, which is extremely strong and very light in weight.
The present structure provides a ladder that is capable of being formed in one molding step, and the parts of the ladder are so designed as to not only enable said molding operation, but to give maximum strength where required, together with minimum material for such strength. Inasmuch as the finished ladder is an excellent non-condoctor of electricity, it is particularly suitable for linemen and for others that may find occasion to use the ladder where it would be dangerous to use ladders of other material.
Other objects and advantages will appear in the description and in the drawings.
In the drawings,
Fig. 1 is a fragmentary perspective view of a ladder made in accordance with this invention and showing the structure that contributes to the employment of the structure in making an extension ladder.
Fig. 2 is an enlarged sectional view taken along line 2-2 of Fig. 1.
Fig. 3 is an enlarged sectional view taken along line 3-3 of Fig. 1.
In detail, the side pieces of the ladder are generally designated 1, 2, and the rungs are designated 3. The side pieces and rungs are formed integrally in one piece, and each side piece comprises a vertically elongated channel member having sides 4, 5, and a curved bottom wall 6 (Fig. 2
The remaining side is open and may be called the rear side since it would face away from the user when the ladder is in use.
The sides 4, extend divergently relative to each other from bottom wall 6, and their inner surfaces 7 are preferably flat. The sides 4, 5 are progressively increasing in thickness along their free edges, as best seen at 8 in Fig. 2, which increased thickness along said edges serves to strength the side pieces. Otherwise the thickness of the material forming said sides is of uniform thickness, preferably of about one quarter of an inch, but this inice 2 vention is not restricted to such thickness for the ladder may be made of any dimensions found most desirable for the jobs to be done.
Each of the rungs 3 is also a channel member. Said rungs have laterally opening sides that are directed in the same direction as the open sides of the vertically extending side pieces 1, 2 when the latter are vertical.
The upper side 10 of each rung slants slightly upwardly in a rearward direction (the rear side being the open side that is directed away from the user) and said side 10 'is of progressively increasing thickness in said rearward direction.
The lower side 11 of each rung extends divergently relative to side 10 in a rearward direction and bottom wall 12 is curved transversely of the length of each rung and integrally joins sides 10, 11. Y
The side 11 of each rung curves downwardly (in a rearward direction) rather steeply from a point spaced slightly rearwardly of bottom wall 12, thus producing a generally vertically extending marginal portion 13 along the open side of each rung, which marginal portion acts like a truss for supporting weight in said rung.
The rungs 3 extend between the opposed sides 5 of side pieces 1, 2 and positioned between the sides 4, 5 of each side piece at each end of each rung is a web 15 (Fig. 2)
that joins the sides 4, 5 of each side piece to materially stiffen and strengthen each of said side pieces.
Also, spaced along rungs 3 and between upper and lower sides 10, 11 of each rung are webs 16 integrally connecting said sides thus stifliening the rungs (Fig. 3).
The webs 15 that are between the sides 4, 5 of the side pieces 1, 2 are curved along their rearwardly directed free edges at the open sides of said side pieces, and as these webs are horizontal (when the side pieces are vertically extending), their curved rear edges extend horizontally. Said curved rear edges of the webs 15 substantially correspond to the horizontal cross sectional contour of the outer side of the bottom wall 6 of each side piece.
In an extension ladder, the upper section 20 (Fig. 1) and the lower section 21, have paralleLside pieces of the same spacing and are positioned so that the curved bottom wall 6 of the side pieces of the section extend be tween the walls 4, 5 of the side pieces of the other section and against the curved edges 17 of webs 15 thus said webs form guides slidably supporting the side pieces of one of the two sections. If it were not for said webs, the side pieces would jam one within the other, but with this structure they readily slide relative to each other.
The conventional straps 25 (only two are shown, there usually being another set spaced from these along the ladders) hold the ladder sections together. The usual supports in extension ladders (not shown) at the lower end of the upper one, serve to hold the upper ladder in extended position. No claim is made to such supports since they are old and are readily adapted to the present ladders.
From the structure shown, it is not only apparent that the ladder can be readily molded in one piece, but the structure that contributes to that result also contributes to strengthening the ladder and bracing the side pieces and rungs against any tendency to twist or to bend when the ladder is in use.
I claim:
1. In a ladder having elongated generally vertically extending side pieces disposed in a common plane in side by side horizontally spaced relation, vertically spaced rungs extending between and connecting said side pieces, said rungs being in the form of horizontally extending channel members having an upper side wall and a lower side wall and a bottom wall connecting them along one of their longitudinally extending edges and the sides of said rungs opposite. their. bottom walls being open and generally directed perpendicular to said plane, the lower side Wall of each rung being curved downwardly in cross sectional contour transversely of each rung and the upper side Wall of each rung. having a substantially flat upper side extending slightly upwardly relative toa horizontal plane in direction toward its free edge when said side pieces are vertical.
2. An extension ladder comprising apair of ladder sections each having. a pair of elongated parallel side pieces equally spaced apart and with the side pieces of one section aligned with those of the other section in direction transversely of said sections, each of said side pieces being in the form of a channel having generally opposed side Walls and a bottom wall? connecting them along one of their free edges with their side opposite said bottom wall being. open, the bottom walls of theside pieces of one pair extending into the. open sides of the Side pieces of the other. pair, and means within the. said. side pieces of said other pair slidably engaging the said bottom walls that extend into said open sides for sliding one of said ladder sections longitudinally thereof relative to the other and means connecting said sections for holding them together during such sliding, the open sides ofthe side pieces of said sections being directed laterally of the plane in which the side pieces of each section are disposed.
3. An extension ladder comprising a pair of ladder sections each having a pair of elongated parallel side pieces equally spaced apart and with the side pieces of one section aligned with those of the other section in direction transversely of said sections, each of said side pieces being in the form of a channel having generally opposed side walls and a bottom wall connecting them alongone of their free edges with their side opposite said bottom wall being open, the bottom. walls of the side pieces of one pair extending into the open sides of the side pieces of the other pair, and means within the said side pieces of said other pair slidably engaging the said bottom Walls that extend into said open sides for sliding one of said ladder sections longitudinally thereof relative to the other and means connecting said sections for holding them together during such sliding,'saidmeans within. said side pieces being webs connecting the side walls of said last mentioned side pieces reinforcing the latter, the open sides of the side pieces of said sections. being directed laterally of the plane in which the side pieces of each section are disposed.
References Cited in the file of this patent UNITED STATES PATENTS 1,376,150 Miller Apr. 26, 1921 1,731,611 Clark Oct. 15, 1929 1,912,331 Wikstrand May 31, 1933 2,064,803 Grove Dec. 15, 1936 2,127,035 Kirlin Aug. 16, 1938 2,237,329 Bischof Apr. 8, 1941 2,542,398 Crumpton Feb. 20, 1951 2,550,274 Kuhler Apr. 24, 1951 2,588,959 Campbell Mar. 11, 1952 2,613,397 Borkland- Oct. 14, 1952
US367710A 1953-07-13 1953-07-13 Molded ladder Expired - Lifetime US2788167A (en)

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Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2862650A (en) * 1957-07-18 1958-12-02 Columbia Products Co Ladder
US2932358A (en) * 1956-12-04 1960-04-12 Hopfeld Henry Ladder construction and the method for making the same
US2963104A (en) * 1958-07-14 1960-12-06 William F Roth Conductor spreaders and ladder hangers
US3108655A (en) * 1958-09-16 1963-10-29 J H Holan Corp Vehicle tower
US3262517A (en) * 1964-11-18 1966-07-26 Jerry P Malec Bridge crane
DE1454118B1 (en) * 1961-12-18 1971-08-26 Racole Trading And Mfg Co Ltd Folding ladder
EP0327323A1 (en) * 1988-02-04 1989-08-09 Tristian Guy Melland Ladders
EP0462946A1 (en) * 1990-06-20 1991-12-27 MAZZILLI ADELFO & FIGLI S.R.L. Synthetic and glass fibre portable ladder
US6138792A (en) * 1997-02-07 2000-10-31 Morris; Tony M. Portable climbing apparatus
US20060032705A1 (en) * 2004-08-16 2006-02-16 Isham William R Lightweight composite ladder rail having supplemental reinforcement in regions subject to greater structural stress
US20070205053A1 (en) * 2004-08-16 2007-09-06 Isham William R Molded composite climbing structures utilizing selective localized reinforcement
US20080251969A1 (en) * 2007-02-16 2008-10-16 Isham William R Bladder Molding Systems and Methods For Fabricating Composite Articles

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1376150A (en) * 1920-01-14 1921-04-26 Albert F Miller Joint-lock
US1731611A (en) * 1927-09-28 1929-10-15 Clark Ralph Otto Telescoping ladder
US1912331A (en) * 1931-11-05 1933-05-30 Wikstrand Anders Ladder-like structure
US2064803A (en) * 1933-08-23 1936-12-15 Claire W Grove Wall step
US2127035A (en) * 1936-07-28 1938-08-16 Otis M Kirlin Ladder
US2237329A (en) * 1937-10-27 1941-04-08 Dowst Mfg Company Toy assembly
US2542398A (en) * 1945-07-28 1951-02-20 Mary Crumpton Murray Ladder
US2550274A (en) * 1946-07-16 1951-04-24 American Car & Foundry Co Grab iron or ladder rung
US2588959A (en) * 1947-01-18 1952-03-11 Harry L Campbell Extension ladder and hoist therefor
US2613397A (en) * 1946-05-29 1952-10-14 Owens Corning Fiberglass Corp Manufacture of molded articles

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1376150A (en) * 1920-01-14 1921-04-26 Albert F Miller Joint-lock
US1731611A (en) * 1927-09-28 1929-10-15 Clark Ralph Otto Telescoping ladder
US1912331A (en) * 1931-11-05 1933-05-30 Wikstrand Anders Ladder-like structure
US2064803A (en) * 1933-08-23 1936-12-15 Claire W Grove Wall step
US2127035A (en) * 1936-07-28 1938-08-16 Otis M Kirlin Ladder
US2237329A (en) * 1937-10-27 1941-04-08 Dowst Mfg Company Toy assembly
US2542398A (en) * 1945-07-28 1951-02-20 Mary Crumpton Murray Ladder
US2613397A (en) * 1946-05-29 1952-10-14 Owens Corning Fiberglass Corp Manufacture of molded articles
US2550274A (en) * 1946-07-16 1951-04-24 American Car & Foundry Co Grab iron or ladder rung
US2588959A (en) * 1947-01-18 1952-03-11 Harry L Campbell Extension ladder and hoist therefor

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2932358A (en) * 1956-12-04 1960-04-12 Hopfeld Henry Ladder construction and the method for making the same
US2862650A (en) * 1957-07-18 1958-12-02 Columbia Products Co Ladder
US2963104A (en) * 1958-07-14 1960-12-06 William F Roth Conductor spreaders and ladder hangers
US3108655A (en) * 1958-09-16 1963-10-29 J H Holan Corp Vehicle tower
DE1454118B1 (en) * 1961-12-18 1971-08-26 Racole Trading And Mfg Co Ltd Folding ladder
US3262517A (en) * 1964-11-18 1966-07-26 Jerry P Malec Bridge crane
EP0327323A1 (en) * 1988-02-04 1989-08-09 Tristian Guy Melland Ladders
EP0462946A1 (en) * 1990-06-20 1991-12-27 MAZZILLI ADELFO & FIGLI S.R.L. Synthetic and glass fibre portable ladder
US6138792A (en) * 1997-02-07 2000-10-31 Morris; Tony M. Portable climbing apparatus
US20060032705A1 (en) * 2004-08-16 2006-02-16 Isham William R Lightweight composite ladder rail having supplemental reinforcement in regions subject to greater structural stress
WO2006023365A2 (en) * 2004-08-16 2006-03-02 Isham William R Lightweight composite ladder rail having supplemental reinforcement in regions subject to greater structural stress
US20070205053A1 (en) * 2004-08-16 2007-09-06 Isham William R Molded composite climbing structures utilizing selective localized reinforcement
WO2006023365A3 (en) * 2004-08-16 2007-10-04 William R Isham Lightweight composite ladder rail having supplemental reinforcement in regions subject to greater structural stress
US20080251969A1 (en) * 2007-02-16 2008-10-16 Isham William R Bladder Molding Systems and Methods For Fabricating Composite Articles

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