U.S. patent application number 10/994785 was filed with the patent office on 2005-06-02 for anti-slip attachment for ladders.
Invention is credited to Corston, Charles.
Application Number | 20050115766 10/994785 |
Document ID | / |
Family ID | 34573047 |
Filed Date | 2005-06-02 |
United States Patent
Application |
20050115766 |
Kind Code |
A1 |
Corston, Charles |
June 2, 2005 |
Anti-slip attachment for ladders
Abstract
An anti-slip attachment for a ladder that forms a frictional
engagement between the ladder and a metal gutter, so as to prevent
the ladder from slipping laterally thereon. A layer of resiliently
compressible material having a high surface coefficient of friction
against smooth metal is mounted to the ladder so that it will bear
against and be compressed by an edge of the gutter. The layer of
resiliently compressible material may be at least one strip of
resiliently compressible foam tape. The resiliently compressible
material may be adhered directly to the side rails of the ladder so
as to bear against the edge of a gutter when the ladder is rested
thereon, or the layer or layers of resiliently compressible
material may be mounted to a separate frame or bracket that is in
turn mounted to the ladder itself. The anti-slip attachment helps
to reduce the likelihood of fall injuries due to the ladder
slipping sideways along a metal gutter during use.
Inventors: |
Corston, Charles;
(Bellingham, WA) |
Correspondence
Address: |
TODD N. HATHAWAY
119 N. COMMERCIAL ST. #620
BELLINGHAM
WA
98225
US
|
Family ID: |
34573047 |
Appl. No.: |
10/994785 |
Filed: |
November 22, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60524134 |
Nov 20, 2003 |
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Current U.S.
Class: |
182/107 |
Current CPC
Class: |
E06C 7/46 20130101; E06C
7/486 20130101 |
Class at
Publication: |
182/107 |
International
Class: |
E04G 005/02 |
Claims
What is claimed is:
1. An anti-slip attachment for a ladder that forms a frictional
engagement between said ladder and a metal gutter, said anti-slip
attachment comprising: a layer of resiliently compressible material
having a high surface coefficient of friction against smooth metal;
and means for mounting said layer of resiliently compressible
material to a ladder so that said layer will bear against and be
compressed by an edge of a metal gutter when said ladder is rested
thereon; whereby said layer of resiliently compressible material
establishes a frictional engagement that prevents said ladder from
slipping laterally along said edge of said gutter.
2. The anti-slip attachment of claim 1, wherein said layer of
resiliently compressible material comprises: at least one elongate
strip of said resiliently compressible material.
3. The anti-slip attachment of claim 2, wherein said means for
mounting said layer of resiliently compressible material to a
ladder comprises: a layer of adhesive on said strip of resiliently
compressible material for adhering said strip to a face of at least
one elongate side rail of a ladder.
4. The anti-slip attachment of claim 3, wherein said strip of
resiliently compressible material comprises: a roll of resiliently
compressible tape having said layer adhesive formed thereon.
5. The anti-slip attachment of claim 1, wherein said means for
mounting said layer of resiliently compressible material to a
ladder comprises: a frame having said layer of resiliently
compressible material mounted to a face thereof; and means for
mounting said frame to a ladder so that said face of said frame
bears against a gutter when said ladder is rested thereon.
6. The anti-slip attachment of claim 5, wherein said frame
comprises: first and second clip members that are attachable to
first and second side rails of a ladder so that said layers of
resiliently compressible material are positioned between said side
rails and a gutter when said ladder is rested thereon.
7. The anti-slip attachment of claim 5, wherein said frame
comprises: first and second bracket members for fitting over first
and second side rails of a ladder so that said layers of
resiliently compressible material are positioned between said side
rails and a gutter when said ladder is rested thereon; and a tie
rod for passing through a stave of said ladder so as to join said
brackets and secure said bracket members on said side rails of said
ladder.
8. The anti-slip attachment of claim 1, wherein said layer of
resiliently compressible material comprises: a layer of resiliently
compressible foam material.
9. The anti-slip attachment of claim 8, wherein said resiliently
compressible foam material comprises: resiliently compressible PVC
foam material.
10. The anti-slip attachment of claim 1, wherein said layer of
resiliently compressible material comprises: a layer of resiliently
compressible material having a durometer selected so that said
layer will be only partially compressed when pressed against an
edge of a gutter by a ladder at a predetermined angle and maximum
load, so that said layer will retain a reserve range of compression
when said ladder is fully loaded.
11. The anti-slip attachment of claim 10, wherein said durometer is
selected so that said layer will be compressed only about 50
percent when pressed against an edge of a gutter by a ladder at
said predetermined angle and maximum load, so that said layer will
retain a reserve range of compression of about 50 percent when said
ladder is fully loaded.
12. An anti-slip ladder assembly that forms a frictional engagement
with a metal gutter, said ladder assembly comprising: a ladder; and
a layer of resiliently compressible material having a high surface
coefficient of friction against smooth metal, said layer of
compressible material being mounted to said ladder so that said
layer will bear against and be compressed by an edge of a metal
gutter when said ladder is rested thereon; whereby said layer of
resiliently compressible material establishes a frictional
engagement that prevents said ladder from slipping laterally along
said edge of said gutter.
13. The anti-slip ladder assembly of claim 12, wherein said layer
of resiliently compressible material comprises: an elongate strip
of resiliently compressible material that is mounted to a face of
at least one elongate side rail of said ladder.
14. The anti-slip ladder assembly of claim 12, wherein said layer
of resiliently compressible material comprises: first and second
elongate strips of resiliently compressible material adhered to
faces of first and second side rails of said ladder.
15. The anti-slip ladder assembly of claim 12, wherein said
assembly further comprises: a frame having said layer of
resiliently compressible material mounted to a face thereof; and
means for mounting said frame to a said ladder so that a said face
of said frame bears against a gutter when said ladder is rested
thereon.
16. The anti-slip ladder assembly of claim 15, wherein said frame
comprises: first and second clip members that are attachable to
first and second side rails of a ladder so that said layers of
resiliently compressible material are positioned between said side
rails and a gutter when said ladder is rested thereon.
17. The anti-slip ladder assembly of claim 15, wherein said frame
comprises: first and second bracket members for fitting over first
and second side rails of a ladder so that said layers of
resiliently compressible material are positioned between said side
rails and a gutter when said ladder is rested thereon; and a tie
rod for passing through a hollow stave of said ladder so as to join
said brackets and secure said bracket members on said side rails of
said ladder.
18. The anti-slip ladder assembly of claim 12, wherein said layer
of resiliently compressible material comprises: a layer of
resiliently compressible foam material.
19. The anti-slip ladder assembly of claim 18, wherein said
resiliently compressible foam material comprises: resiliently
compressible PVC foam material.
20. The anti-slip ladder assembly of claim 12, wherein said layer
of resiliently compressible material comprises: a layer of
resiliently compressible material having a durometer selected so
that said layer will be only partially compressed when pressed
against an edge of a gutter by a ladder at a predetermined angle
and maximum load, so that said layer will retain a reserve range of
compression when said ladder is fully loaded.
21. The anti-slip ladder assembly of claim 20, wherein said
durometer is selected so that said layer will be compressed only
about 50 percent when pressed against an edge of a gutter by a
ladder at said predetermined angle and maximum load, so that said
layer will retain a reserve range of compression of about 50
percent when said ladder is fully loaded.
22. A method for forming a frictional engagement between a ladder
and a metal gutter, said method comprising the steps of: mounting
to a ladder a layer of resiliently compressible material having a
high surface coefficient of friction against smooth metal; and
resting said ladder against a metal gutter so that said layer of
resiliently compressible material bears against and is compressed
by an edge of said metal gutter; whereby said layer of resiliently
compressible material establishes a frictional engagement that
prevents said ladder from slipping laterally along said edge of
said gutter.
23. The method of claim 22, wherein the step of mounting said layer
of resiliently compressible material to a ladder comprises:
mounting an elongate strip of said resiliently compressible
material to a face of at least one elongate side rail of said
ladder.
24. The method of claim 23, wherein the step of mounting an
elongate strip of said resiliently compressible material to at
least one side rail of said ladder comprises adhering first and
second strips of said resiliently compressible material to first
and second side rails of said ladder.
25. The method of claim 22, wherein the step of mounting said layer
of resiliently compressible material to a ladder comprises:
mounting said layer of resiliently compressible material to a face
of a frame; and mounting said frame to said ladder so that said
face of said frame bears against a gutter when said ladder is
rested thereon.
26. The method of claim 22, wherein the step of mounting a layer of
resiliently compressible material to a ladder comprises: mounting
to said ladder a layer of resiliently compressible foam
material.
27. The method of claim 26, wherein said resiliently compressible
foam material is a PVC foam material.
28. The method of claim 22, further comprising the step of:
selecting said layer of resiliently compressible material to have a
durometer such that said layer will be only partially compressed
when pressed against an edge of a gutter by said ladder at a
predetermined angle and maximum load, so that said layer will
retain a reserve range of compression when said ladder is fully
loaded.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 60/524,134 filed on Nov. 20, 2003.
BACKGROUND
[0002] a. Field of the Invention
[0003] The present invention relates generally to safety devices
for ladders, and, more particularly, to an attachment for
preventing ladder from slipping laterally against a gutter during
use.
[0004] b. Background
[0005] Ladders in general, and extension ladders in particular,
present significant safety concerns. It is well documented that
falls from ladders result in numerous injuries and deaths on an
annual basis.
[0006] One particular hazard is the tendency of ladders to slip
sideways when resting against gutters. As can been seen in FIG. 1,
a person 10 when cleaning or repairing a gutter 12 tends to reach
out to one side or the other when working, due to the inconvenience
involving in descending and moving the ladder 14 to another
location, with the result that this unbalances the ladder and tends
to cause it to slide laterally on the gutter and possibly topple
over. Even more dangerous is the tendency of the ladder to slip
when attempting to step onto it from the roof in order to descend,
when the user is facing backwards and feeling for a rung with his
foot.
[0007] The frequency of this hazard is increasing due to the
increasing use of aluminum (and other metal and slippery-surfaced
materials) in the construction of both gutters and ladders. For
example, when an aluminum extension ladder is placed against an
aluminum gutter there is almost no frictional resistance to the
ladder sliding laterally.
[0008] As a partial solution, some ladders have been fitted with
various forms of stabilizing struts and braces which rest against
the ground. These are at best only a partial solution, and become
less effective as the ladder is extended to increased heights.
Moreover, the struts and braces are cumbersome and make the ladder
to difficult to store or transport, and also add significant
cost.
[0009] Accordingly, there exists a need for an attachment for
effectively preventing a ladder from slipping laterally when placed
against a gutter or similar structure or surface. Furthermore,
there exists a need for such an attachment that is effective
regardless of the height to which the ladder is extended. Still
further, there exists a need for such an attachment that does not
encumber the transportation or storage of the ladder, or otherwise
compromise its use. Still further, there exists a need for such an
attachment that can be used with a wide variety of conventional
ladders, both new and those already in use, without requiring
significant modification thereof. Still further, there exists a
need for such an attachment that is inexpensive and yet durable and
long lasting in use.
SUMMARY OF THE INVENTION
[0010] The present invention has solved the problems cited above,
and is an anti-slip attachment for a ladder that forms a frictional
engagement between the ladder and the metal gutter or similar
structure when the ladder is placed thereon.
[0011] Broadly, the invention comprises (a) a layer of resiliently
compressible material having a comparatively high surface
coefficiency of friction against smooth metal, and (b) means for
mounting the layer of resiliently compressible material to a ladder
so that the layer will bear against and be partially compressed by
the edge of the gutter when the ladder is rested thereon.
[0012] The layer of resiliently compressible material may comprise
a strip of the resiliently compressible material, and the means for
mounting the material to the ladder may comprise an adhesive for
being adhered to the forward faces of the side rails of the ladder.
The strip may comprise a roll of the resiliently compressible
material having an adhesive backing.
[0013] Alternatively, the means for mounting the layer of
resiliently compressible material to the ladder may comprise a
frame having the resiliently compressible material mounted to a
face thereof, and means for mounting the frame to the ladder. The
frame may comprise first and second clips that are mountable to the
side rails of the ladder so that the faces having the layer of
resiliently compressible material are directed towards the gutter
when the ladder is placed thereon.
[0014] The resiliently compressible material may comprise a
resiliently compressible foam material. The resiliently
compressible foam material may be a PVC foam material.
[0015] The layer of resiliently compressible material may be
configured so that the material will be only partially compressed
when forced against the gutter under a predetermined maximum
operating load of the ladder, so that the layer of resiliently
compressible material will retain a reserve range of compression
when the ladder is fully loaded. The reserve range of compression
may be about 50% of the total range of compression of the layer of
material.
[0016] The present invention also provides an anti-slip ladder
assembly, comprising (a) a ladder, and (b) a layer of resiliently
compressible material having a comparatively high surface
coefficient of friction that is mounted to the ladder so as to bear
against and engage an edge of a gutter when the ladder is placed
thereon. The layer of resiliently compressible material may
comprise first and second strips of resiliently compressible
material that are adhered to the faces of first and second side
rails of the ladder. The resiliently compressible material may
comprise strips of resiliently compressible foam material having an
adhesive backing. The resiliently compressible material may
comprise resiliently compressible PVC foam material. The layer of
resiliently compressible material may be configured so that the
material will be only partially compressed when forced against the
gutter under a predetermined maximum operating load of the ladder,
so that the layer of resiliently compressible material will retain
a reserve range of compression when the ladder is fully loaded. The
reserve range of compression may be about 50% of the total range of
compression of the layer of material.
[0017] The invention further provides a method for forming a
frictional engagement between a ladder and a metal gutter,
comprising the steps of mounting to a ladder a layer of resiliently
compressible material having a high surface coefficient of friction
against smooth metal, and resting the ladder against a metal gutter
so that the layer of resiliently compressible material establishes
a frictional engagement that prevents the ladder from slipping
laterally along the edge of the gutter.
[0018] These and other features and advantages of the present
invention will be apparent from a reading of the following detailed
description with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is an elevational, environmental view of a ladder in
accordance with the prior art, showing the manner in which this
tends to slip along the gutter as the operator reaches to one
side;
[0020] FIG. 2 is an elevational view of a ladder having an
anti-slip attachment in accordance with the present invention
adhered thereto, showing the manner in which the attachment engages
the metal gutter of a house when placed thereon;
[0021] FIG. 3 is an enlarged, cross-sectional view of the area of
contact between the ladder of FIG. 2 and the gutter against which
it is placed, showing the manner in which the compressible layer of
the anti-slip attachment yields resiliently to conform to and
engage the surface of the gutter;
[0022] FIG. 4 is an elevational, partial view of a ladder having a
strip of compressible material being applied thereto from a roll of
the material, so as to form the anti-slip attachment of FIGS.
2-3;
[0023] FIG. 5 is an elevational view, similar to FIG. 2, showing an
anti-slip attachment in accordance with a second embodiment of the
present invention, in which the yieldingly compressible material is
mounted to a pair of clips that are fitted over the side rails of
the ladder, the ladder being shown in a cross-section taken along
line 5-5 in FIG. 6;
[0024] FIG. 6 is an elevational view of the ladder and anti-slip
attachments of FIG. 5, showing the position of the clips on the
side rails of the ladder; and
[0025] FIG. 7 is a cross-sectional view of the ladder and anti-slip
attachments of FIGS. 5-6, taken along line 7-7 in FIG. 6, showing
the manner in which the clips fit over and engage the side rails of
the ladder;
[0026] FIG. 8 is an elevational view, similar to FIG. 5, showing an
anti-slip attachment in accordance with a third embodiment of the
present invention, in which the yieldingly compressible material is
mounted to a pair of channel-shaped frames that are slipped over
the side rails of the ladder;
[0027] FIG. 9 is a perspective view of one of the slip-on,
channel-shaped frames of FIG. 8, showing the configuration of the
frame and the strip of resiliently compressible material thereon in
greater detail;
[0028] FIG. 10 is a first partial, elevational view of the ladder
and one of the slip-on frames of FIGS. 8-9, showing the manner in
which the upper end of a side rail enters and is received in the
channel-shaped frame as the latter is slid onto the rail;
[0029] FIG. 11 is a second partial, elevational view of the side
rail and slip-on frame of FIG. 10, showing the manner in which the
side rail fits within and is engaged by the channel-shaped frame as
the frame is slid onto the rail and into the desired position;
[0030] FIG. 12 is a cross-sectional view, taken along line 12-12 in
FIG. 11, showing the relationship of the channel-shaped frame and
strip of resiliently compressible material to the side rail of the
ladder in greater detail; and
[0031] FIG. 13 is a cross-sectional view of an anti-slip attachment
assembly in accordance with a fourth embodiment of the present
invention, showing the manner in which the brackets thereof are
mounted by a threaded rod which passes through one of the staves of
the ladder.
DETAILED DESCRIPTION
[0032] The present invention is an anti-slip attachment for a
ladder which frictionally engages the surface of a metal gutter or
similar surface structure so as to prevent the ladder from sliding
thereon. FIGS. 2-7 illustrate two embodiments of the invention.
[0033] In the first preferred embodiment that is illustrated in
FIG. 2, the attachment is formed of a strip of resiliently
compressible material 20 that is adhered to the forward face 22 of
each rail 24 of the ladder 26. The surface of the resiliently
compressible layer 20 will consequently bear against the lip 28 of
the gutter 30 when the ladder is placed thereon, as shown in FIG.
2.
[0034] The pressure of the ladder against the gutter causes the lip
28 of the gutter to press into the resilient material of the
anti-slip attachment, as shown in FIG. 3. This causes the
resiliently compressible material to deform so that its surface
follows the contour of the gutter lip, forming a contact patch 32
having an increased surface area. The compressible material is
selected to have surface qualities similar to that of soft rubber,
i.e., it has a high degree of "tackiness" and resistance to
slipping when pressed against a smooth metal surface. The material
thus has a high surface coefficient of friction, e.g., a static
coefficient of friction (.mu..sub.s) well above 0.5 and preferably
above about 0.9.
[0035] The large contact patches 32 consequently establish a firm
frictional engagement with the lip of the gutter that prevents the
ladder from sliding laterally thereon. Moreover, any tipping
movement will cause the rail of the ladder on the side towards the
direction of tipping to slide downwardly (as well as laterally)
against the gutter (see FIG. 1); as this happens, the material of
the compressible strip in the area 34 just above the contact patch
(see FIG. 3) will tend to build or "mound" up so as to abut the
upper surface 36 of the gutter lip, further acting to arrest the
movement of the ladder.
[0036] In combination, these actions of the resiliently
compressible strips (i.e., the frictional engagement of the contact
patch in combination with the abutment of the material against the
upper surface of the gutter lip) are extremely effective in
preventing the ladder from developing any tipping or sliding motion
during use; in prototype testing, using anti-slip strips in
accordance with the preferred embodiment of the present invention,
it has been found essentially impossible for a person to cause the
ladder to slide laterally against an aluminum gutter, even when
pulling forcefully in a sideways direction on the gutter
itself.
[0037] Another particular advantage of the elongate configuration
of the strips of resiliently compressible material is that this
makes it very easy for the operator to position the anti-slip
material against the edge of the gutter, regardless of differences
in the height of the gutter above the ground. As is well know, the
height of most extension ladders is adjustable only in increments
(typically, by the distance between the individual staves of the
ladder); the vertical length of the elongate strips avoids the
problem of the anti-slip areas being positioned above or below the
gutter when the ladder is adjusted to the nearest incremental
height. The elongate dimension of the strips also prevents them
from moving off of and losing contact with the edge of the gutter
in the event that some movement occurs that changes the angle of
the ladder relative to the gutter. For most conventional extension
ladders, it is preferred that the length of the strips be at least
as great as the spacing between the staves/rungs (e.g., about 10-16
inches), although much longer strips (e.g., 3-5 feet or more) may
be advantageous from the standpoint of convenience. Moreover, it
will be understood that in some embodiments the resiliently
compressible, anti-slip material may be provided in other shapes
besides elongate, rectangular strips, for example, in an oval or
rounded configuration.
[0038] In order for the anti-slip strips to provide the above
advantages, it is important that the resiliently compressible
material be selected to have a durometer, or indentation hardness,
in combination with its thickness such that it will significantly
compress but will not "bottom out" against the ladder rails 22
under normal loads. In other words, the material is preferably
selected so that, when the ladder with which it is used is at its
maximum normally acceptable inclination and working load, with the
rails of the ladder pressing against the edge of the gutter, the
material will not be completely collapsed and will retain a degree
of compressible travel. Thus, as is shown in FIG. 3, even when the
ladder is bearing the full load of a user and associated tools,
etc., the material of the strips 20 has not bottomed out, and an
area 38 of reserve compression remains available between the gutter
lip and the forward faces 22 of the ladder rails. The amount of
reserve compression may vary depending on design factors, however,
it is generally suitable that the material be selected to yield by
about 50% of its total available compression when subjected to a
maximum operating load of the ladder within a specified range of
lean angles.
[0039] As can be seen with further reference to FIG. 3, each of the
strips 20 of the anti-slip attachment of the preferred embodiment
is formed by a layer of resiliently compressible foam material 40
backed by a layer of adhesive 42 that affixes the compressible
material to the face 22 of the rail. FIG. 4, in turn, illustrates a
method in which the anti-slip material is conveniently supplied in
the form of a roll 34 of adhesive cushioning tape. This can be
packaged and supplied to the purchaser, separately from or together
with the ladder as desired, and is easily applied to the faces of
the rails 24 by simply unrolling the tape in a conventional fashion
and pressing it against the surface 22 so that the material adheres
firmly thereto. It will be understood, however, that other forms of
application may be employed, for example, the resiliently
compressible material may be extruded or molded directly on the
faces of the ladder rails in an OEM operation, or may be formed as
an integral part of the faces of the rails themselves.
[0040] Suitable adhesive foam tape material is available from
Saint-Gobain Performance Plastics, Granville, N.Y., with equivalent
products being available from other manufacturers. Cellular PVC
(polyvinyl chloride) foam material is generally preferred due to
its comparatively high surface coefficient of friction and its
ability to establish firm frictional engagement under both wet and
dry conditions, plus its overall durability and resistance to
abrasion; it will be understood, however, that other resilient
materials may be used, such as urethane, polyurethane, silicone or
rubber foams or various non-cellular rubber-like materials, for
example. Using firm PVC foam material in readily available
durometers, suitable dimensions for the adhesive tape are 11/8
inches wide by 3/8 inch thick, which again may vary depending on
design factors.
[0041] One example of an eminently suitable high-density,
closed-cell PVC foam material, available from Saint-Gobain
Performance Plastics, has the properties set forth in the following
Table A:
1TABLE A Properties Test Method Value Thickness, inches (mm) .375
(8.5) Hardness Shore OO 52 Density lbs./ft.sup.3 (kg/m.sup.3) ASTM
D1667 15 (240) Compression Force Deflection psi ASTM D1667 9 (64)
(kPa) @ 30% Force to Compress, psi (kPA) @ ASTM D1667 14 (94)
30%
[0042] In the second embodiment, which is illustrated in FIGS. 5-7,
there are first and second clips, 50a, 50b that attach to the two
rails 52a, 52b of the ladder and which engage the lip 28 of the
gutter 30 in substantially the same manner as described above. The
clips consequently provide separate frames on which the tape is
mounted, which are in turn mountable to the ladder.
[0043] As can be seen in FIG. 7, each of the clips is formed in the
shape of semi-enclosed channel. In the illustrated embodiment the
channel is constructed of steel-sheet metal, however, it will be
understood that plastic or other suitable materials may be used.
The channel includes a comparatively wide web 54 having a flange 56
along its forward edge, the strip of foam material 58 being adhered
to the outer surface thereof. A second flange 58 along the opposite
edge of the web 54 is bent back parallel to the web so as to form a
return 60 that defines semi enclosed U-shaped channel area 26. The
inside angle between the web and the forward flange 56 is somewhat
less than 90.degree., e.g., 80-85.degree..
[0044] To install one of the clips on a rail of the ladder, the
U-shaped channel area 60 is first slipped over the rearward flange
64 of the ladder rail and the clip is then pulled/pushed forwardly.
When the rearward flange of the ladder is fully seated against the
rearward flange 58 of the clip, as is shown in FIG. 7, the forward
flange 56 is bent forwardly to widen the spacing between the
forward and rearward flanges of the clip sufficiently that the
former can be slipped over the forward flange 66 of the ladder
rail. When the clip has been pressed home, so that its web lies
generally parallel to the web 68 of the ladder rail, the forward
flange 56 snaps resiliently back to its initial orientation to lock
the clip in place. The strip of resiliently compressible anti-slip
material is thus positioned so that it will be compressed between
the gutter and the rail of the ladder during use.
[0045] In a third embodiment, which is illustrated in FIGS. 8-12,
there are two channel-shaped frames 70a, 70b (only 70a being
visible in FIG. 8), that have a channel-shaped configuration and
that slip over the two side rails 72a, 72b of the ladder rather
than clipping onto them in the manner shown in FIGS. 5-7.
[0046] As can be seen in FIG. 9, each of the slip-on frames has a
generally channel-shaped configuration, with a side web 74 and
forward and rearward flanges 76, 78 with returns 80, 82, that in
combination define a semi-enclosed, U-shaped channel area 84; the
generally U-shaped configuration facilitates manufacture of the
frames from stamped/bent sheet metal, however, it will be
understood that in some embodiments that the channel areas may be
fully enclosed. A strip 86 of the resiliently compressible material
is mounted to the forwardly-directed face of each forward flange
76, in a manner similar to the embodiment described with regard to
FIGS. 5-7. However, at the upper and lower ends of the rearward
flange 78 a pair of ramp-shaped biasing members 88a, 88b protrude
inwardly towards the channel area 84. In the embodiment that is
illustrated, the biasing members are formed of separate pieces of
resiliently flexible material (e.g., metal or plastic), each having
a mounting portion 90 that is spot welded, bonded or otherwise
mounted to the inside surface 92 of the rearward flange 78 (see
FIG. 10), with a leaf portion 94 that bends forwardly from the
mounting portion so as to extend into the channel area. This
provides the advantage of being able to form the biasing members of
a material having superior resiliency and wear characteristics as
compared with the material of the frame; however, it will be
understood that in some embodiments the biasing members may be
formed integrally (e.g., stamped or molded) with and of the same
material as the frame itself.
[0047] As can be seen in FIG. 10, the side web 74 and therefore the
channel area 84 is sized somewhat wider than the side rail of the
ladder. The leaf portions 94 of the biasing members 88a, 88b
include main ramp portions 96 that extend into the channel area to
define a width that in turn is less than that of the side rails;
distal ramp portions 98 at the ends of the main ramp portions are
angled back outwardly towards the rearward side of the frame.
[0048] Accordingly, as can be seen in FIG. 10, the frame members
70a, 70b can be slid onto the upper ends of the side rails 72a,
72b, in the direction indicated by arrow 100. As this is done, the
distal ramp portion 98 contacts and rides over the upper, rearward
corner of the side rail (which is typically radiussed as shown), so
that the leaf portion of the biasing member is forced outwardly in
the direction indicated by arrow 104. As a result, the leaf portion
develops an inward bias against the rearward surface 106 of the
rail as the frame is slid thereover.
[0049] As a result, the upper and lower biasing members 88a, 88b
maintain a constant inward pressure towards rails, as indicated by
arrow 110 in FIG. 11. This generates a sliding but comparatively
high-friction engagement at the contact areas between the rearward
surfaces 106 of the rails and the junctures/apexes 108 of the ramp
portions of the biasing members. The frictional engagement is
sufficiently high to hold the frames in place, but low enough to be
overcome by simply grasping the frames and pushing them in one
direction or the other. Consequently, the operator is able to
conveniently slide the frames to the desired location along the
rails, at which the strips of resiliently compressible material
will contact the gutter, after which the frictional engagement will
maintain the frames in position and prevent them from sliding until
the operator next desires to adjust their positions. Furthermore,
as can be seen in FIG. 12, the forward pressure exerted by the
biasing members holds the forward flange of the frame firmly in
place against the front surface 112 of the rail, so as to form a
stable interfit in which the anti-slip strips 86 are properly
positioned at the front edges of the ladder.
[0050] FIG. 13 shows a fourth embodiment of the invention, in which
the frames 120a, 120b have a somewhat simplified configuration,
with the forward and rearward flanges 122, 124 extending at right
angles to the webs 126. As with the embodiments described above,
the strips of resiliently compressible cushioning material 128 are
adhered to the outer surfaces of the forward flanges 122. In this
embodiment, however, mounting is accomplished by means of a
threaded rod 130 that passes through a hollow interior of one of
the staves 132 of the ladder; conventionally, the staves of
aluminum ladders are hollow and open at each end so that the rod
can be readily passed therethrough. First and second wing nuts 134
are mounted on the ends of the rod 130 and secure the clips to the
rails of the ladder when tightened; suitably, the rod is a 20-inch
length of 1/4-inch ready rod, with 1/4-inch wing nuts on each end.
However, it will be understood that in some embodiments a nut may
be used on only one end of the rod, with the other end being a bolt
head or fixed to the opposite clip; moreover, other attachment and
tightening means may be used in other embodiments.
[0051] The embodiments which are shown in FIGS. 5-13 illustrate
just a few of many different structures that may be used to provide
an anti-slip attachment in which the resiliently compressible
material mounts to the ladder via a secondary structure or frame
rather than being adhered directly to the ladder rails themselves.
As a general rule, those embodiments which employ secondary
structures that are faced with the non-slip compressible material
may be somewhat more costly than the first embodiment described
above (i.e., in which the compressible tape is adhered directly to
the faces of the rails), however, they may offer certain advantages
in terms of being able to provide contact patches that are wider
(and therefore "grippier") than those which are limited to the
width of the individual rails of the ladder. It will be understood,
however, that all such embodiments fall within the scope and spirit
of the present invention, regardless of the whether the resiliently
compressible material is mounted directly on the rails of the
ladder or on a secondary frame or structure that in turn mounts to
the rails and/or staves of the ladder.
[0052] It is to be recognized that various alterations,
modifications, and/or additions may be introduced into the
constructions and arrangements of parts described above without
departing from the spirit or ambit of the present invention.
* * * * *