Note: Descriptions are shown in the official language in which they were submitted.
CA 02537289 2006-02-17
Lamming Device for Climbing and Use Thereof
Field of the Invention:
This invention is related to devices to assist rock and mountain climbers.
Specifically, this
invention is a climbing cam that has a superior range as a result of long-
lasting high friction
material on the face of the cam and low weight "rope" stem.
Background of the Invention:
Mountain climbing is a sport of limits. Rock climbers are relentlessly
striving to push these
limits by enduring personal physical pain, improving technical climbing
abilities and inventing
innovative technical gear. Lowering weight and increasing strength of climbing
gear are the
fundamental improvements that are required to extend the limits of climbable
routes. Fall
protection is the key aspect to this. Fall protection is what a climber uses
to secure
himself/herself to the rock face while climbing. In the event of a fall, the
"fall protection" will
stop the climber falling to their death. Fall protection requires a delicate
balance between
strength requirements and weight conservation.
A climbing camming device (cam or friend) is one type of device used as fall
protection by
mountain climbers. Primarily used for crack climbing, the cam is inserted into
a crack and the
safety rope is fixed to the stem loop. Friction from the rock/aluminum lobe
interface and the
outward normal force generated by the unique cam lobe shape holds the camming
device in the
crack when loaded by a fall. Lamming devices have revolutionized rock climbing
because
climbing routes with parallel crack systems can now be protected. Also, unlike
pitons or other
forms of permanent protection, camming devices do not damage the rock and are
easily placed
and removed.
Lamming devices range in size and consist of two to four aluminum spring-
loaded cams (lobes)
with a logarithmic spiral contact shape. These cams are mounted onto a
stainless steel axle and
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CA 02537289 2006-02-17
connected to a 3 / 16" 302 stainless steel aircraft cable stem. The climbing
rope is fixed to the
stem with standard nylon webbing and when weighted the downward force on the
stem forces
the cams to spread and hold into the rock.
When traveling to and from the climbing site, and while on a climb, a climber
must carry a full
range of caroming devices in order to accommodate various crack sizes. For
this reason, it is
necessary to consider the weight of the rack of caroming devices. Various
approaches have been
taken to reduce the weight. Firstly, aluminum is used as much as possible as
it is lighter than
steel. Second, the weight has been further reduced by introducing apertures
into the caroming
devices. As the number of axles used also affects the weight of a caroming
device, weight can be
reduced by using single axle caroming devices, rather than the heavier double
axle caroming
devices. These approaches reduce the weight of each caroming devices, and
therefore, the
weight of the rack.
An alternative approach to lightening the weight of the rack, is to reduce the
number of caroming
devices that needed to be carried. This can be done by increasing the range a
given caroming
device. Expansion range is the maximum minus the minimum crevice size a
caroming device
will tolerate. Double axle caroming devices have more expansion range than
single axle
caroming devices, hence fewer caroming devices need to be carried. However,
this gain may be
offset by the increased weight of the double axle caroming devices over that
of the single axle
caroming devices.
The problem for climbers is how to reduce the weight required for climbing
while remaining
within an acceptable safety margin, based on fit of the caroming device in the
crack and strength
of the caroming device. It is an object of the present invention to overcome
the deficiencies of
the prior art.
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CA 02537289 2006-02-17
Summary of the Invention:
An improved camming device is provided that has a superior range of operation,
is lighter and
has lower internal compressive forces. A camming device is for use as
protection in cracks
during rock climbing, and comprises at least one pair of lobes, one axle per
pair of lobes, a stem,
a loop and a release mechanism. The lobes comprise: a face having a contact
area; an inside
edge; an apical end; and a basal end, to define an inner surface and an outer
surface. The
improvement comprises a semi-metallic composition affixed to the contact area.
The composition may comprise metals selected from the group consisting of
aluminum, brass,
bronze and copper. The composition may be semi-metallic. By semi-metallic it
is meant that a
portion, ranging from a trace to a substantial amount of the composition is
metal, but that it is
only one component of the composition, which may comprise one or more other
components.
In another aspect of the invention the composition is housed in a recess in
the face.
In another aspect of the invention the recess extends substantially from the
apical end to the basal
end.
In another aspect of the invention the recess terminates in a tab at the
apical end and a tab at the
basal end.
In another aspect of the invention the composition has a co-efficient of
friction in the range of
0.35-0.55.
In another aspect of the invention the co-efficient of friction is in the
range of 0.45-0.55.
In another aspect of the invention the co-efficient of friction is about 0.46.
In another aspect of the invention the composition is affixed with an
adhesive.
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CA 02537289 2006-02-17
In another aspect of the invention the semi-metallic composition is
additionally mechanically
affixed.
In another aspect of the invention, an improved camming device is provided
that has a superior
range of operation, is lighter and has lower internal compressive forces. A
camming device is for
use as protection in cracks during rock climbing, and comprises at least one
pair of lobes, one
axle per pair of lobes, a stem, a loop and a release mechanism. The lobes
comprise: a face
having a contact area; an inside edge; an apical end; and a basal end, to
define an inner surface
and an outer surface. The improvement comprises a semi-a composition having a
co-efficient of
friction ranging between 0.35-0.55 affixed to the contact area.
In another aspect of the invention the composition is housed in a recess in
the face.
In another aspect of the invention the recess extends substantially from the
apical end to the basal
end
In another aspect of the invention the recess terminates in a tab at the
apical end and a tab at the
basal end.
In another aspect of the invention the co-efficient of friction is in the
range of 0.45-0.55.
In another aspect of the invention the co-efficient of friction is about 0.46.
In another aspect of the invention, the composition is comprised of a metal
selected from the
group consisting of aluminum, copper, bronze and brass.
In another aspect of the invention, the composition is a semi-metallic
composition.
In another aspect of the invention the composition is affixed with an
adhesive.
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CA 02537289 2006-02-17
In another aspect of the invention the composition is additionally
mechanically affixed.
In yet another aspect of the invention, an improved method of fall protection
cracks during rock
climbing is provided. The method comprises employing a caroming device having
a maximum
range of about 0.9"-1.18".
In another aspect of the invention the maximum range is about 1.0"-1.18".
In another aspect of the invention the caroming device has a co-efficient of
friction on a contact
area between 0.45 and 0.50.
In another aspect of the invention the caroming device has a co-efficient of
friction of about 0.46.
In another aspect of the invention, a rack of climbing cams is provided having
five caroming
devices providing an operational range of approximately 4.0 inches.
In another aspect of the invention, the rack comprises four caroming devices
providing an
operational range of approximately 2.6 inches.
In another aspect of the invention, the rack comprises three caroming devices
providing an
operational range of approximately 1.7 inches.
In another aspect of the invention, the caroming device has two axles and two
pairs of lobes.
In another aspect of the invention, the loop comprises a composite cord.
In another aspect of the invention, a method of manufacturing an improved a
caroming device is
provided. The caroming device is comprised of at least one pair of lobes, one
axle per pair of
lobes, a stem, a loop and a release mechanism, the lobes comprising: a face
having a contact
CA 02537289 2006-02-17
area; an inside edge; an apical end; and a basal end, to define an inner
surface and an outer
surface. The method comprises increasing the static co-efficient of friction
on a contact area by
affixing a semi-metallic composition to the contact area.
In another aspect of the method, the semi-metallic composition is housed in a
recess in the face.
In another aspect of the method, the recess extends substantially from the
apical end to the basal
end.
In another aspect of the method, the recess terminates in a tab at the apical
end and a tab at the
basal end.
In another aspect of the method the semi-metallic composition has a co-
efficient of friction is in
the range of 0.35-0.55.
In another aspect of the method the semi-metallic composition has a co-
efficient of friction is in
the range of 0.45-0.55.
In another aspect of the method the semi-metallic composition has a co-
efficient of friction of
about 0.46.
In another aspect of the method the semi-metallic composition is affixed with
an adhesive.
In another aspect of the method the semi-metallic composition is additionally
mechanically
affixed.
In another aspect of the invention, the method further comprises utilizing a
suitably selected
composite cord for manufacture of the loop.
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CA 02537289 2006-02-17
Figures:
Figure 1 is a perspective view of a caroming device in accordance with an
embodiment of the
invention.
Figure 2 is an exploded view of the caroming device of Figure 1.
Figure 3A and B are drawings of the radius of the extended and contracted
caroming device of
Figure 1.
Figure 4 is a perspective view of a lobe of the caroming device of Figure 1.
Detailed Description of the Invention:
A caroming device for climbing, generally referred to as 10, is shown in
Figure 1. The caroming
device 10 has two cams 12 in parallel relation to each other, each comprising
two lobes, an inner
lobe 14 and an outer lobe 16, for engaging a crack when actuated. The lobes
14, 16 are
aluminum. The two cams 12 are rotatably mounted on a stainless steel axle 18,
by means of a
bore 20, such that inner lobes 14 oppose one another and the outer lobes 16
oppose one another
as shown in Figure 2. The lobes 14, 16 define a radius that expands as the
caroming device 12 is
actuated, as shown in Figure 3A and B. Each lobe 14, 16 is generally
triangular and has a face
22, and an inside edge 24 terminating at an apical end 26, and a basal end 28
opposing the apical
end 26 as shown in Figure 4. An inner surface 30 and outer surface 32 are
defined by the face
22, edge 24 and ends 26, 28. The face 22 has a logarithmic contact shape, with
the contact area
34 comprising a semi-metallic composition. The semi-metallic composition is
brake pad
material, having a static coefficient of friction of about 0.46 when contacted
with rock. The
semi-metallic composition on the contact area 34 is affixed using adhesive and
is housed in a
recess 36 of the lobe 14, 16 with tabs 38, 40 extending from the apical end 26
of the lobe 14, 16
and the basal end 28, of the lobe 14, 16 as shown in Figure 4. The semi-
metallic composition
increases holding power, allows for an increased operational range and lowers
internal
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CA 02537289 2006-02-17
compressive forces. A stop 42 subtends the recess 36 in the vicinity of the
basal end 28 and
protrudes from the inner surface 30 of the outer lobe 16 and the outer surface
32 of the inner lobe
14, such that the stop 42 of one lobe 14 abuts the basal end 28 of the other
lobe 16, when the
caroming device 10 is fully retracted. In this position, the caroming device
10 may function as
passive protection.
The axle 18 is retained in the bore 20 of the lobes 14, 16, by means of a hub
44 on either end 46
of the axle 18. Between the pairs of cams 12, a stem 48 comprising a composite
cord made of
ParallayTM construction HMPE fibre is rotatably mounted on the axle 18. A
washer 47 is located
on the axle 18 between the stem 48 and each inner lobe 14. A loop 50 is
affixed to a distal end
52 of the stem 48 by splicing. A guide, 51, is rotatably mounted on the axle
18 and accepts the
stem 48. .
A release mechanism 56 is slidably mounted on the stem 48 by a plate 58 with a
centrally located
release bore 60, through which the stem 48 slides. Adjacent the release bore
60 on either side of
the release bore 60 are a pair of bores 64 through which a resilient member,
such as a cable 66 is
threaded. The cable 66 is aligned such that the distance between the two lobes
14, 16 and the
plate 58 is the same. Each lobe 14, 16 has an aperture 54 to accept the cable
66. The aperture 54
on the outer lobe 16 is on the outer surface 32 and the aperture 54 on the
inner lobe 14 is also on
the outer surface 32. The cable 66 of the release mechanism 56 is rotatably
within the aperture
54.
The lobes 14, 16 are biased from one another in a cam 12 by biasing means,
such as a spring 68.
Hence, when downward pressure is exerted on the caroming device 10, the cams
12 spring open
into an actuated position, in which the face 22 with its contacting surface
34, engages a crack by
abutting opposing rock walls of the crack. When the climber wants to release
the caroming
device 10 from the crack, he pulls the plate 58 of the release mechanism 56
away from the rock
while pushing the stem 48 in towards the rock, and the caroming device 10 is
released. The
caroming device 10 is then returned to a rack of caroming devices.
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CA 02537289 2006-02-17
Example 1
Detailed friction testing of five advanced composite friction materials
against 8 different types of
rock, laboratory testing of twelve different two-part adhesives (including
expoxies, acrylics and
urethanes) for break away and internal strength and extensive research into
new market products,
in terms of cords, heat shrink tubing and metal based putties was carried out.
This led to
inventing a caroming device with an 81.3% increase in the standard working
range and a 34.5%
reduction in stem weight.
Table 1: Friction Material Testing
Co-Efficient of Friction (u)
(Frictional Force/Normal Force)
AFT-
Friction Materials HF-61 9010 1006 AFT-200 Al-6106 F4-3-2S2
Rock Types
Black Sandstone 0.38 O.S8 0.45 0.35 0.48 0.38
Green Sandstone 0.48 0.41 0.62 O.S3 O.S3 0.64
Yellow Quartzite O.S9 0.62 0.62 O.SS O.S2 O.SS
Pink Quartzite 0.63 0.61 0.66 0.06 0.42 O.S8
Gneiss O.S3 0.66 O.S6 0.47 0.42 0.46
Basalt 0.33 O.SS 0.33 0.39 0.34 0.45
Limestone 0.43 O.SS 0.27 0.39 0.36 0.23
White Granite 0.67 0.67 O.SI 0.54 0.45 0.43
Average Co-Efficient
of
Friction O.S1 O.S8 O.SO 0.41 0.44 0.47
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CA 02537289 2006-02-17
Claimed Co-Efficient
of
Friction 0.61 0.46 0.52 0.42 0.31 0.41
Corrected Test Values 0.36 ~.41 ~ 0.35 0.29 0.31 0.33
The introduction of a high frictional co-efficient material to the rock / lobe
interface increases the
frictional forces of the cam. This increased holding power allows for an
increased operational
range and lower internal compressive forces. The operational ranges for a set
of cams of the
present invention is shown in Table 3. The increase in range for #6 Trango cam
is 0.35" this
corresponds to a 49.3% increase. The increase in range for a #7 Trango cam =
1.36" which
translates to an 81.3% increase.
Table 3: Cam operational ranges
Cam Trango Improved cam
#6 1.38 to 2.09 1.56 to 2.62
#7 1.89 to 2.64 2.60 to 3.96
#8 2.40 to 3.58
*All in inches*
The lobe shape of the cam is a logarithmic spiral defined as:
y, ' ecB
Where: r = radius of spiral
a = natural logarithm
CA 02537289 2006-02-17
c = coefficient defining how fast the spiral opens
0 = angle measured in radians
The coefficient c, in equation (1) is limited by the coefficient of friction
between the rock and the
lobe interface. The claimed 0.42 coefficient of friction for material 9010 was
used for the
coefficient c in the lobe shape equation. TrangoTM #7 (size 7 in Trango's
range of cams) cam
was used in the prototype model of the caroming device, so the lobe size
coefficient which
factors the lobe equation to determine size is 0.515. This coefficient ensures
that the vertical
distance from the axle to the lobe surface is 1.00", the distance for Trango
cams. Figures 3A and
B show an extended and a contracted cam lobe, demonstrating the range
dimensions of the lobes
for extended and contracted positions, respectively. The specified range of
Trango's #7 Flex cam
is 1.89" to 2.64" for a maximum range of about 0.75". As shown in Figures 3A
and B, the
improved range is 2.60" to 3.96" for a maximum range of about 1.36". The range
of the
improved caroming devices of the present invention are shown relative to
Trango caroming
devices. It can be seen from Table 3 that the range of the caroming devices
are significantly
greater and hence, fewer caroming devices are needed to cover the range of
sizes. As would be
known to one skilled in the art, the range is determined from a logarithmic
equation, hence the
percentage change in range will be exponential. For example, after detailing
another cam of
Trango's (the #6), the range increase was found to be 49.3%. This reduces the
number of
caroming devices needed for a given rack.
Table 2: Adhesives Evaluated
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32629 /2IP228B 18,000 no-mix urethane
/ cP,
amber,
two-part
326 /
7649
38402 3IV8700D roethacrylate
acrylic
adhesive.
1,900/2,800
cP,
ultra
clear,
5
minute
work
life,
E-OSCL 29299 3I29723A
two-part
mercaptan
epoxy.
U-OSFL 29348 3AZ9618A 640/35,000
cP,
off
white,
5
minute
work
life,
two-
11
CA 02537289 2006-02-17
part polyurethane adhesive.
The foregoing is a description of an embodiment of the invention. As would be
known to one
skilled in the art, there can be variations in design of the camming device
that do not change the
scope of the invention. For example, the caroming device can be a single cam
or double cam
device. The plate of the release mechanism may be machined or forged metal, or
may be
injection moulded and comprise a polymeric material. The stops may be
contoured flush with
the face of the lobe. The composite cord can be comprised of, for example, but
limited to non-
metallic advanced climbing or sailing materials and can be spliced, knotted,
sewn, glued, or
mechanically fastened to form a loop. The cord is the main tensile load
bearing member of the
caroming device. Suitable materials and means of fastening would be known to
one skilled in
the art. A protective sheath can surround the loop in the stem. The semi-
metallic composition
may be affixed to the face of the lobe by mechanical means or by a combination
of mechanical
and adhesive means. Further, a ceramic composition might replace the semi-
metallic
composition, and this would alter the coefficient of friction accordingly.
Still further, the semi-
metallic composition can be replaced with soft metals, such as, but not
limited to Aluminum
5052 and 3003, coppers, brasses, and bronzes, that have a co-efficient of
friction of about 0.35
and higher. The coefficient of friction can range from about 0.35- 0.55. These
and other
modifications are within the scope of the invention.
12
