Note: Descriptions are shown in the official language in which they were submitted.
CA 02796485 2012-11-22
LADDER RING CAGE
FIELD OF THE INVENTION
[0001] The present invention relates generally to building equipment, and
more particularly to ladder cages for use with scaffolding and other
structures.
BACKGROUND
[0002] Tall structures such as communications towers, wind turbines,
scaffolding, and the like are often equipped with a ladder that may be climbed
to
reach points of elevation on the structure, for service or the like. Often,
such
ladders provide the only easy access to these points of elevation. As well,
the
ladders typically extend completely vertically, to significant heights and
present a
risk to a climber.
[0003] As such, these ladders are often surrounded by generally semi-
circular
rings, affixed at either side of the ladder typically along the extent of the
ladder.
Vertical bars extend between the rings. The rings and bars define a ladder
cage,
and provide security for the climber to inhibit a downward or outward fall
away
from the ladder.
[0004] Typically, these rings are securely affixed to the ladder, and as
such
are not easy to install and cannot be easily moved or removed. For some
structures, however, easy removal and installation are desirable.
[0005] As such, there remains a need for a ladder cage assembly that may be
easily installed and removed.
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SUMMARY
[0006] In accordance with an aspect of the present invention, there is
provided a ladder cage comprising: a plurality of spaced rings, having
fasteners
attached thereto; a plurality of vertical braces, each having a mounting hole
proximate each end, and extending between two of the plurality of rings, and
attached at either end to respective ones of the fasteners; wherein each of
the
fasteners comprises a mounting pin having a slot therein, and a drop pin
slidably
mounted to that fastener for sliding in and out of its slot in its mounting
pin; and
wherein an associated vertical brace is fastened to a ring by that fastener,
as its
mounting pin is received in the mounting hole of the associated vertical
brace,
and the drop pin of the fastener is received in the slot of said mounting pin,
wherein the drop-pin makes an angle of between about 300 and 600 to the
vertical.
[0007] In accordance with another aspect of the present invention, there is
provided a ring for forming a ladder cage comprising: a ring shaped body
having
fasteners attached thereto; each of the fasteners comprising a mounting pin
having a slot therein, and a drop pin slidably mounted to that fastener for
sliding
in and out of its slot in its mounting pin, wherein the drop pin is mounted so
it
may make an angle of between 30 and 60 ' to the vertical; and wherein an
associated vertical brace may be fastened to the ring by that fastener, as its
mounting pin is received in the mounting hole of the associated vertical
brace,
and the drop pin of the fastener is received in the slot of the mounting pin.
[0008] In accordance with yet another aspect of the present invention,
there is
provided a method of assembling a ladder cage comprising: attaching two
spaced rings having fasteners attached thereto to a ladder; each of the
fasteners
comprising a mounting pin having a slot therein, and a drop pin slidably
mounted
to that fastener for sliding in and out of its slot in its mounting pin,
wherein the
drop pin is mounted at an angle of between about 30 and 60 to a plane of its
ring; attaching a vertical brace to the two spaced rings by inserting a
mounting
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pin of corresponding ones of the fasteners on each of the two spaced rings
into a
hole of the vertical brace; and sliding a drop pin mounted to each of the
corresponding one of the fasteners to rest at an angle of between 300 and 60
to
the vertical into a slot in their mounting pins to fasten the vertical brace
to the ring
by the fastener on each of the two spaced rings.
[0009] Other aspects and features of the present invention will become
apparent to those of ordinary skill in the art upon review of the following
description of specific embodiments of the invention in conjunction with the
accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] In the figures which illustrate by way of example only, embodiments
of
the present invention,
[0011] FIG. 1 is a perspective view of a ladder and ladder cage, exemplary
of
an embodiment of the present invention;
[0012] FIG. 2 is a perspective view of a brace of the ladder cage of FIG.
1;
[0013] FIG. 3 is a perspective view of a ladder cage ring of the ladder
brace of
FIG. 1; and
[0014] FIG. 4 is a perspective view of a fastener of the ladder cage of
FIG. 1.
DETAILED DESCRIPTION
[0015] FIG. 1 is a perspective view of ladder cage 10, exemplary of an
embodiment of the present invention. Ladder cage 10 provides support/safety to
a climber of ladder 12. Ladder 12 may be part of a free standing structure
(otherwise not shown), such as a building scaffold, a wind turbine tower, a
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communications tower, or the like. As illustrated, ladder cage 10, when
assembled forms a generally cylindrical cage that encircles a climber of
ladder
12. Ladder cage 10 is affixed around ladder 12, to provide protection to a
climber in case of a backward/outward fall.
[0016] Cage 10 includes several rings 14-1, 14-2, 14-3,... 14-n
(individually
and collectively rings 14¨ only three are illustrated in FIG. 1), and vertical
braces
16 extending between rings 14 in the direction of extent of ladder 12. Ladder
cage 10 may be formed in several sections 18-1, 18-2, 18-3,... 18-n
(individually
and collectively sections 18) ¨ with each section defined by two adjacent
rings 14
and the vertical braces 16 between them. Sections 18 may extend continuously
along the length of ladder 12, or discontinuously, with sections separated by
a
space. Rings 14 are spaced along the extent of ladder 12, typically, but not
necessarily, at equal distances from one another.
[0017] Vertical braces 16 are typically identical, having like dimensions.
For
convenience, vertical braces 16 in a section 18 ¨ i.e. between the same two
rings
14- are identified with a common subscript in FIG. 1. Thus, in FIG. 1,
vertical
braces 161 all interconnect rings 14-1 and 14-2 in section 18-1; vertical
braces
162 all interconnect rings 14-2 and 14-3 in section 18-2; vertical braces 163
all
interconnect rings 14-3 and 14-4 in section 18-3; and so on.
[0018] As illustrated in FIG. 2, each vertical brace 16 may take the form
of a
standard scaffold brace, formed of steel or aluminium, having a flattened ends
28, extending from a generally cylindrical body portion 26. Each flattened end
28
may further include a hole 24 for mounting brace 16 on a corresponding
mounting pin. The mounting pin may take the form of a pin, a bolt, a post, a
shaft, or any other suitable protrusion.
[0019] As more particularly illustrated in FIG. 3, each ring 14 includes an
arc
shaped metal or alloy band 22, having several fasteners 30 extending outwardly
therefrom, and evenly spaced along band 22. Band 22 may be formed of the
same material as brace 16¨ i.e. steel, aluminium, or the like.
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[0020] Each fastener 30 serves to secure one or two vertical braces 16 to a
ring 14. For a ring 14 shared by two sections 18 of cage 10, a single fastener
30
receives an upwardly extending vertical brace 16, and a downwardly extending
brace 16, as best illustrated by the enlarged portion of FIG. 1. The end of
band
22 may be folded inwardly, and further include bolt and nut 60, 62 or similar
fastener for bolting ring 14 to ladder 12. The arc formed by band 22 is sized
so
that its inwardly folded ends of band 22 attach to vertically extending struts
of
ladder 12, at equal vertical positions along ladder 12, thus levelling the
plane of
ring 14 horizontally. Of course, as will be appreciated, ring 14 need not be
formed of a flat band, but could instead be formed with a tubular cross-
section
tube, or having any other suitable cross-sectional geometry. Likewise, rings
14
need not be formed in circular arc shapes. For example, rings 14 may instead
be
rectangular, elliptical or formed in any other simple or complex shapes
suitable
for a given application. In the depicted embodiment, the distance between
folded
ends of band 22 is about 60 cm, the length of each brace 16 is about 1 m, and
braces 16 are circumferentially spaced by about 20 cm around ring 14.
[0021] An example fastener 30 for fastening brace 16 to ring 14 is more
particularly illustrated in FIG. 4. As illustrated, fastener 30 includes a
mounting
pin 32 mounted on a base 34, and a U-shaped drop-pin 40. Base 34 may be
attached to ring 14, and includes a slot 36. Slot 36 is in a plane tangent to
ring
14. Mounting pin 32 includes a further slot 38, in plane normal to that of
slot 36.
U-shaped drop pin 40 has a curved top 42 and two flat arms 44 and 46 and is
slidably received within slot 36. Flat arms 44 and 46 are also oriented in
planes
normal to each other, so that arm 44 may be received in slot 36, and slide
freely
therein, while arm 46 may be slid in, out of, and through slot 38. A nib 48 on
arm
44 stops arm 44 from being completely slid through slot 36, thus preventing U-
shaped drop pin 40 from being separated from base 34. Alternatively, or
additionally, arm 44 may include a hole for receiving a cotter pin or the like
for
preventing drop pin 40 from being separated from base 34. Optionally, arm 46
may include a hole 50 on arm 46 for receiving a cotter-pin 52 or the like, to
lock
U-shaped drop pin 40 in place (as shown in FIG. 1). Slots 36 and 38 and arms
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44 and 46 are depicted as flat, but could take any suitable complementary
shapes. For example, slots 36, 38 and arms 44 and 46 could be round in cross-
section, semi-circular in cross-section, or any other suitable shape.
[0022] As further illustrated in FIG. 1, U-shaped drop pin 40 is used to
lock a
flattened end 28 of brace 16 in place on mounting pin 32. Conveniently, U-
shaped drop pin 40 is pulled out of base 34 to open fastener 30, and allow
hole
24 of brace 16 to slide on and off of pin 32, past slot 38. U-shaped drop pin
40
may be sized and oriented so that, when drop pin 40 is pulled out of base 34
as
far as nib 38 permits, sufficient horizontal space is provided between pin 32
and
arm 46 so that arm 46 clears the vertical edges of end portion 28 of brace 16,
as
hole 24 is slid onto pin 32.. After hole 24 is slid onto pin 32, drop pin 40
may be
slid into slot 38 to close fastener 30, and optionally locked by pinning
cotter-pin
52 into hole 50. Drop pin 40 may also be sized and oriented to provide
sufficient
horizontal space beteween pin 32 and the inside of curved top 42 so that, once
hole 24 is slid onto pin 32 drop pin 40 may be closed with arm 46 fully in
slot 38
before the inside of curved top 32 contacts the vertical edges of end portion
28.
Of course, in order for fastener 30 to be able to accept both upwardly and
downwardly-extending braces 16 with vertical end portions 28, drop pin 40
should be at an angle to the vertical that will depend on the geometry of
fastener
30 and end portions 28.
[0023] Fastener 30 is mounted to ring 14, so that U-shaped drop pin 40
slides
at an angle of about a=45 to the vertical (i.e. at an angle a to the plane of
ring
14) . In this way, U-shaped drop pin 40 is naturally pulled by gravity into
slot 36.
Once drop pin 40 is slid into slot 38, it locks one or more braces 16 into
place on
pin 32, preventing brace 16 from sliding off pin 32. Likewise, the size and
angled orientation of U-shaped drop-pin 40, provides clearance for both an
upwardly and downwardly extending brace 16 to be received on pin 32. As will
now be appreciated, mount angles of less than or more than 45 may achieve the
same effect. The mount angle may be any angle which provides sufficient
clearance for braces 16, given the geometry of drop pin 40, and that result in
a
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sufficient downward pull of drop pin 40 into slot 36 by gravity. For example,
angles of between 300 and 60 may be appropriate.
[0024] Conveniently, ring 14 with fasteners 30 allow for relatively quick
assembly of ladder cage 10. Two adjacent rings 14 may be attached to ladder
12, and braces 16 may be attached to these rings 14. U-shaped drop pins 40
may be quickly and readily slid between the open and closed position of
fastener
30, to allow for easy installation of braces 16. At the same time, the effect
of
gravity biases U-shaped drop-pins 40 closed. With the aid of gravity, use of
cotter-pins 52 is optional.
=
[0025] Ladder cage 10 may similarly be disassembled, to allow easy removal,
by sliding U-shaped drop pins 40 upward, providing clearance to allow the
flattened ends 28 of braces 16 to be slid outward, off of pins 32. Once braces
16
are removed from rings 14, rings 14 may be removed from ladder 10.
[0026] As will be appreciated U-shaped drop pins 40 could be replaced with
drop pins of another shape ¨ for example linear drop pins could be used.
[0027] In an alternate embodiment, fastener 30 (and hence drop pin 40)
could
be mounted to ring 14 so that it may be rotatable or pivotal about an axis of
pin
32. The drop pin 40 could be rotated to an arbitrary angular position as
braces
16 are installed. For example, to suit a particular application or the
preference of
an installer, fastener 30 could be rotated so that drop pin 40 is in a
substantially
horizontal orientation, parallel to the plane of ring 14, as the braces 16 are
installed. Thereafter, the pin could be rotated to make a suitable angle with
the
vertical to lock drop pin 40 with the aid of gravity after brace(s) 16 is/are
installed
[0028] Of course, the above described embodiments, are intended to be
illustrative only and in no way limiting. The described embodiments of
carrying
out the invention, are susceptible to many modifications of form, arrangement
of
parts, details and order of operation. The invention, rather, is intended to
encompass all such modification within its scope, as defined by the claims.
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