Note: Descriptions are shown in the official language in which they were submitted.
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Title: FAT.T. ARREST BELT ASSEMBLY
FIEI.D OF Tf~E~ INVENTION
This invention relates to fall arrest belt
assemblies used by workers who climb wooden utility poles
and large trees.
BACKGROUND OF THE INVENTION
While today's line worker tends to rely on a
hydraulic ~oom and bucket to reach electrical power lines
or telephone poles, there are still instances where the
line worker must manually climb a pole. This is the case
where the pole cannot be reached hy the boom truck, for
example, a pole situated in the middle of a field in a
rural setting. Having less practice, the worker is a~
increased risk of falling during such climbing.
I5 To climb a pole, the line worker typically uses
climbing spikes or spurs, and a climbing belt made from
leather or suitable synthetic material. The climbing belt
passes around the far sid~ of the pole and attaches to a
body-belt or harness which is worn by the line worker.
The climbing spikes face inward to the pole and penetrate
the pole giving the climber purchase for climbing. The
climbing belt provides a climbing aid to the climber and
also holds him to the pole and helps support his weight,
freeing his hands.
While the climbing belt helps support the
climber if used during ascent and descent (and also in the
work position), problems occur if the climber loses his
ooting and begins to fall. In such a situation, or, if
the worker has been standing upright on his spurs to be
close to the pole and its equipment, and he then slips,
the pressure of the climber's weight against the climbing
belt may be relieved, so that the belt no longer pulls
against the pole. This permits the climber to fall and be
seriously injured or even killed. To arrest the climber
during a fall, various fall arrest features have been
incorporated into climber safety devices.
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U.S. Patent No. 4,407,391, which issued to
Greenway et al., on October 4, 1983 discloses a fall
arrest device comprising a yoke with a safety belt attach-
ment and handles for the climber. The yoke is formed ~rom
5 metal and closes around the pole. On the underside of the
yoke, there ar0 blades which can pivot and which, in their
closed position, bite into the pole. Either counter-
weights on the blades, or torsion springs, hold them in
the closed position. In operation, the climber holds the
blades in the open position and lifts the yoke as he
climbs the pole. Should the climber fall, he will nor-
mally release the blade handles and they will close either
by the spring action or by the ~orce of the counter-
weights, and will bite into the pole.
The device as taught by Greenway suffers a major
drawback, namely, ease of use in the field. It will be
appreciated that the usefulness of a fall arrest device
depends on the line climber's willingness to use it. The
~reenway device, besides being very heavy when compared to
conventional safety belts, is very difficult to operate
around obstructions on the pole ~which are frequent).
Furthermore, the yoke is not readily adjustable to differ-
ent size poles. For these reasons, climbers have been
quite reluctant to use this fall arrest device.
U.S. Patent No. 4,579,196, which issued to Allen
et al. on April 1, 1986, discloses a climber fall arrest
belt assembly having an outer strap and an inner strap.
The oute~ strap includes downwardly directed teeth which
are designed to bite into the pole. The outer strap wraps
around the outside surface of the utility pole and con-
nects to the climber's body-belt. The inner strap clips
across the outer strap on the inner side of the pole but
requires adjustment by the worker to fit the pole. In the
event o~ a fall the teeth on the outer strap bite into the
pole and the inn~r strap cooperates with the outer strap
by bearing the climber's weight to stop the fall. The
Allen invention suffers from the major drawback of having
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the fall arresting teeth always in the engaged position.
Not only can the teeth catch during normal ascent and
descent of the pole, but also the points on the teeth will
tend to dull, thereby risking a failure in the event of
the fall. In addition, the Allen invention uses friction
between the inner strap and utility pole to bear some of
the fallen climber's weight.
Accordingly, the problem remains to provide a
fall arrest assembly which is reliable and easy to use by
a line worker or other climber in the field. The prior
art, while teaching various fall arrest devices, fails to
provide a device which is not cumbersome and which does
not interfere with the climber's normal ascent or descent
of a utility pole. In addition, in the prior art, adjust-
ment of the device to the changing diameters oi poles isusually awkward.
SU~MARY OF THE INVENTIO~
Accordingly/ it is an object of the present
invention to provide a fall arrest device for a line
worker or other climber which lends itself to ease of use
in the field and which does not interfere with normal
ascent or descent while providing improved fall protec-
tion.
In one aspect, the present invention provides a
belt assembly for use with a body belt worn by a climber
for climbing a utility pole or the like, said belt assem-
bly comprising:
(a) an outer strap adapted to fit around said util-
ity pole, said outer strap having a pair of ends
adapted to be attached to said body belt,
(b) a cross-over strap having a pair of ends con-
nected to said outer strap at locations spaced
from the ends of said outer strap, said inner
strap being adapted to define and maintain, with
the portion of said outer strap extending
between the ends of said inner strap, a closed
snug loop around said pole,
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(c) a safety device connected to said portion of
said outer strap,
(d~ said safety device having a tooth, and means
mounting said tooth for movement between an open
position and a closed position,
~e) said safety device further including latching
means coupled to said tooth and normally retain-
ing said tooth in said closed position,
(f~ said safety device including tooth deployment
means responsive to said cli.mber falling, for
releasing said tooth from said latching means
and for moving said tooth into said open posi-
tion so that said tooth will penetrate into said
pole, said deployment means including activation
means for contacting said pole if said climber
falls, for instituting operation of said deploy-
ment means.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the present
invention in its various aspects, and to show more clearly
: how it may be carried into effect, reference will now be
made, by way of example, to the accompanying drawings in
which:
Fig. 1 shows a line worker or other climber
wearing a belt assembly comprising an other strap, a
cross-over strap and a safety device, according to the
present invention;
Fig. 2 is a perspective view of a belt assembly
incorporating the safety device;
Fig. 3 is a side view and sectional view of the
safety device, along line 3-3, in the closed position;
Fig. ~ is a side view and sectional view, along
line 3-3, of the safety device in the open or released
position;
Fig. 5 is a partial sectional view of the safety
device and a locking mechanism for positioning the safety
device on the belt assembly;
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Fig. 6a is a sectional view of the sliding
buckle and a locking mechanism for positioning the buckle
on the outer b01t;
Fig. 6b is a sectional view of the sliding
buckle and another type of locking mechanism for position-
ing the buckle on the outer belt;
Fig. 6c is a sectional view of the sliding
buckle and yet another type of retaining mechanism for
positioning the buckle on the outer belt;
Eig. 7 is a plan ~iew of a climber using the
belt assembly according to the present invention;
Fig. 8 is a side view of a modified buckle for
holding thP cross-over strap to the outer strap; and
Fig. 9 is a perspective view of a modified
connection between the cross-over strap and a buckle on
the outer strap.
DETAILED DESCRIPTION OY THE PREFERRED EMBODIMENTS
Fig. 1 shows a line worker or other climber 1
climbing a utility pole or tree 2 using a belt assembly 10
according to the present invention. The belt assembly 10
attaches to a body-belt 12 worn by the climber 1. The
body-belt 12 has connecting rings 14 (called ~D rings~) at
opposite ends for attaching to the belt assembly 10. In
climbing the utility pole or tree 2, the climber 1 also
wears climbing spikes or spurs (not shown).
Referring to Fig. 2, the belt assembly 10
comprises an outer strap 16, a cross-strap or cord 18, and
a safety device 20. The outer strap 16 fits around the
outer surface of the pole 2. The strap 16 is of conven-
tional design and should be relatively stiff while at thesame time having some flexibility. In known manner, it
can be made oE leather or a webbed nylon or elastomeric
material. The outer strap 16 includes a snap hook 22, 24
at each end for connecting to the corresponding D rings 14
on the body-belt 12 (as shown in Fig. 1). To provide a
secure connection to the body-belt 12 and avoid uninten-
tional release, the snap hooks 22, 24 should each include
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a hinged tongue 26. At one or both ends, the outer strap
16 has an adjustment buckle 28 for varying the length of
the strap 16 to accommodate poles 2 of varying diameters.
Utility poles 2 typically vary between 8 and 18 inches in
diameter. To provide the adjustment capability, tha
buckle end of the outer strap 16 is doubled over and
loc]ced in place using the buckle 2~.
The cross-strap or cord 18 fits across the near
side (i.e. the pole side adjacent to the climber) of the
utility pole 2 (Fig. 1). The cross-strap 18 attaches to
the outer strap 16 using a pair of sliding buckles 30, 31.
Each buckle 30, 31 comprises a front plate 32 and a back
plate 34 which define a recess 35 for accepting the outer
strap 16. Each buckle 30, 31, in turn, attaches to one
end of the cross-strap 18 using a releasable fastener 36.
The fastener 36 includes a pin 37 which extends through
matched holes in a terminating piece 37a on the end of
cord 18, and in protrusions 37b from plate 34. The pin 37
may have a ball detent near its free end so that it cannot
easily be removed inadvertently.
After the outer strap 16 is positioned around
the pole 2, and clipped to the body belt 12 via the D
rings 14 and snap hooks 22, ~4, the climber 1 snaps the
cross-strap 18 in place using the fasteners 36. The
function of the cross-strap 18 is to keep the outer
portion of the outer strap 16 formed in a "loop~ shape
(see Fig. 7) around the pole 2, i.e. to ensure that it
normally hugs or is pulled reasonably tightly around the
pole (except when it is moved away from the pole by the
climber during a climbing step). The ''loopll shape is
ad~usted by sliding the buckles 30, 31 along the outer
strap 16. In addition, the cross-strap 18 keeps the safety
device 20 in proximity to the pole 2 as will be discussed
below.
As will be explained, the cross-strap 18 accord-
ing to the present invention (unlike in conventional fall
arrest belt designs) does not perform a load-sharing
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function. Therefore, the cross-strap 18 can be a bungee
cord, which as known consists of an elastic core sur-
rounded by a stretchable outer sheath.
As shown in Fig. 2, the cross-strap 18 includes
a pair of balls 38 mounted thereon. The balls 38 are
located near the middle of strap 18 and are prevented from
sliding outwardly on the strap 18 by enlargements 19 on
the strap 18. The balls 38 serve two principal func-
tions. Firstly, and primarily, the balls 38 by keeping
the cross-strap 18 away from the surface of the pole 2
reduce abrasion of the bungee cord 18 against the pole 2
as the climber 1 climbs or descends. Secondly, as shown
in Fig. 7, the balls 38 create a space 38a between the
bungee cord 18 and the pole 2 through which the climber 1
can insert his thumbs even when he is wearing bulky gloves
in winter time. The balls 33 are normally positioned
spaced from each other and from the ends of cord 18 to
best accommodate insertion of the climber's gloves. In
the embodiment shown, the balls 18 are approximately
equidistant from each other and from the ends of cord 18,
dividing cord 18 approximately into thirds, and are held
in position against displacement on the cord by enlarge-
ments 19 on the cord 18. However, the balls 38 are
preferably rotatable on the cord 18 (which passes through
holes in the balls) so that the balls can roll up or down
the pole during climbing.
To accommodate varying pole or tree diameters,
the cross-over strap 18 may have integral length adjust-
ability, or cross-over straps of various lengths may be
supplied to the user.
~ he safety device 20 fits onto a portion of the
outer strap 16 between buckles 30, 31, as shown in Fig. 2.
When using the belt assembly 10, it is preferable to have
the safety device 20 on the outer strap 16 in a position
directly across from the climber 1. It is therefore
desirable to adjust the position of the safety device 20
if the climber 1 climbs a utility pole 2 having a differ-
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ent diameter. Alternatively two safety devices 20 can beused on outer strap 16, spaced from each other, to cover
a range of diameters.
Referring both to Fig. 2 and FigO 3 (which shows
the safety device 20 along section line 3-3), the safety
device 20 includes a front plate or housing 40, and a back
plate 42. The back plate 42 fits into a mounting slot 43
on the front plate or housing 40 and is secured using a
suitable ~astener such as a bolt 44. The front plate or
housing 40 can be machined from lightweight alum.inum or
plastic, or can be die-cast or moulded using known
methods. The back plate 42 can simply be cut from metal
plate having a thickness e.g. between 3 mm and 5 mm. The
housing 40 and back plate 42 define between them a slot 45
to accommodate the outer strap 16.
The front plate 40 includes a recess 46 for
housing a tooth 48 as shown in Fig. 2. The tooth 48 is
mounted in the front plate 40 using a hinge pin 50. The
tooth 48 has a slot 52 which accepts the hinge pin 50. As
shown in Fig. 3, the elongated shape of the slot S2 allows
both rotational and longitudinal movement of the tooth 48
about the hinge pin S0. In cooperation with the hinge pin
50, the tooth 48 moves between a closed position 54 (Fig.
3) and an open position 56 (Fig. 4).
The tooth 48 is also connected to a strong coil
spring 58. As shown in Figs. 3 and 4, one end of the
spring 58 fits into a hole 60 drilled in the top surface
of the tooth 48, while the other end of the spring 58 is
attached to the bolt 44 to place the spring under tension.
The spring 58 and slot 50 are arranged in an "over the
centre" configuration. Vsing such an arrangement, the
tooth 48 will stay in the open position 56 until it is
pushed back into the closed position 54.
In the closed position 54 shown in Fig. 3, the
spring 48 is still in tension and produces a force which
tends to pull the tooth 48 into the open position 56. To
keep the tooth 48 in the closed position 54, the underside
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of tooth 48 has a notch 61 defining a release catch 62
which engages with the top edge of the back plate 42. In
the closed position 54, the tooth 48 is held against
premature release, or flopping out, by the release catch
62 resisting the force of the spring 58. In addit.ion,
the spring 58, since it pulls the tooth 48 downwardly,
holds the notch 61 ~irmly over the top edge of the back
plate 42.
To release the tooth 48 ~rom the cocked or
closed position 54, the tooth 48 includes a barb 64
projecting from the front of tooth 48, near the top o~ the
tooth 48. In its simplest form, the barb 64 is a projec-
t.ion formed or machined as an integral part of the tooth
48. The barb 64 has an edge 65 which will catch the
surface of the pole 2 if there is any substantial downward
motion, to force the tooth 48 upwards relative to the
housing 40.
The tooth 48 also includes a stop catch indi-
cated by 66. The stop catch 66 prevents movement of the
tooth 48 past the open position 56. As shown in Fig. 4,
the stop catch 66 is simply a forwardly facing surface
near the rear o~ tooth 48, on the underside of the tooth
structure. The catch 66 abuts against the top edge of
the back plate 42 when the tooth 48 is released or in the
open position 56. The shape of the stop catch 66 deter-
mines how far the tooth 48 will extend in the open posi-
tion. The tooth 48 should not extend too much, otherwise
the safety device 20 may roll over or tumble which will
prevent it from functioning as intended. In the preferred
embodiment, the tooth 48 forms an angle of 15 to 30
degrees, preferably 20 degrees, from the vertical when in
the open position 56.
To use the belt assembly 10 according to the
present invention, the climber 1 places the outer strap 16
around the pole or tree 2 and connects the free ends of
strap 16 to his D rings 14. He then connects the cross-
strap 18 to outer strap 16. By moving the sliding buckles
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30, 31 along the outer strap 16, the loop is adjusted to
the diameter of the utility pole 2. There should be just
enough tension in the loop formed by straps 16, 18 to
prevent the belt assembly from sliding down the pole or
tree by its own weight. To accommodate various pole or
tree diameters, the length of the cross strap 18 may have
to be adjusted. For large diameter poles 2, the outer
belt 16 can first be adjusted using the buckle 28. If
necessary, the safety device 20 should be repositioned on
the outer strap 16 to be directly across from the climber
1 on ~he opposite face of the pole 2. As mentioned, two
or more safety devices 20 can if desired be placed on
outer belt 16 to alleviate the need to change their
position when the belt loop diameter is changed.
The safety device 20 can be secured in position
along the outer strap 16 using a simple conventional
spring biased ball 68, as shown in Fig. 5. The ball 68
will pop partly out when the safety device 20 is posi-
tioned over one of the adjustment holes in the outer strap
16. Other positioning methods can also be used.
During climbing, the climber would normally
grasp the outer belt 16 as shown in Fig. 7 and move it up
or down the pole. With the present invention no major
change in hand position is needed. The climber still
grasps the outer belt 16 as shown in Fig. 7, but now also
grasps with it the cross-strap 18, stretching the cross-
strap 18 as shown, away from the pole, so the outer strap
16 is loosened from the pole and can be moved up or down.
When the climber releases his grip on the straps, the
cross-strap 18 will again tighten the outer strap 16
against the pole.
In the event of a fall, the barb 64 ~which can
be considered as being an activation device) catches the
surface of the utility pole 2 as the climber rapidly moves
down the pole 2. Once the barb 64 catches the pole, the
barb pulls the tooth 48 upwardly ~a translational move-
ment) as allowed by the slot 52. This upward movement of
the tooth 48 causes the release catch 62 to clear the top
edge of the back plate 42 and the tension of the spring 58
then forces the tooth 48 to rotate into the open position
56. In the open position 56, the tooth 48 will bite into
the surface of the utility pole 2. As the downward
momentum of the falling climber 1 is transferred to the
tooth 48 via the body belt 12, the tooth 48 will penetrate
deeper into the pole 2 until the fall is arrested. The
force of the fall is taken by the safety device 20 and the
outer strap 16; relatively little force is absorbed by the
cross-strap or bungee cord 18. In addition the arrest
occurs with only a small movement of the safety device,
thus limiting the fall distance and the deceleration
suffered by the climber.
It will be realized that the translational or
upward movement of tooth 48 which occurs before the tooth
can rotate, has the advantage of delaying the deployment
of the tooth 48 until it is needed. The likelihoocl of
false deployment is thus reduced.
~ith reference still to Fig. 4, when the tooth
48 bites into the utility pole 2, the safety device 20
will tend to pivot about the point of the tooth 48. To
permit greater penetration by the tooth 48, the bottom
portion of the front plate can be bevelled as indicated at
69.
To close the tooth 48 after re-setting his spurs
in the wood, the climber simply pushes on its ~ront
surface (i.e. the surface facing the pole). This rotates
the tooth 48 to its Fig. 3 orientation, and spring 58 then
pulls the tooth 48 down until notch 61 fits over the top
edge of back plate 42.
As noted above, the loop shape formed by the
outer strap 16 and cross-strap 18 is adjusted using the
sliding buckles 30,31 which fit on the outer strap 16. To
keep the sliding buckles 30,31 in their adjusted posi-
tions, the buckles 30,31 include locking mechanisms which
operate in conjunction with a serias of holes 70 in the
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outer strap 16. Fig. 6a shows a first type of lockingmechanism 72. The locking mechanism 72 comprises a
thumbscrew 74 having a threaded portion 75 directly below
the thumbscrew head. The thumbscrew 74 passes through the
hole 70 in the outer strap 16 and a corresponding hole 76
in the back plate 34 of the buckle 30r31~ with the
threaded portion 75 screwing into a corresponding thread
in the front plate 32 of the buckle 30, 31 to secure the
thumbscrew 74.
Fig. 6b shows another form of locking mechanism
to secure the buckles 30, 31 in position along the outer
strap 16. The mechanism comprises a pin 78 having a ring
80 at one end and a spring biased ball 82 at the other
end. Pushing the pin 78 through matching holes in the
buckle 30, 31 and the outer strap 16 causes the ball 82 to
depress until it clears the back plate 34 at which point
it pops out to lock the pin 78 against the back plate 34.
To remove pin 78 the ring 80 is pulled in the opposite
direction which also causes the ball 82 to depress while
the pin 78 is being pulled out.
Fig. 6c shows a third arrangement for connecting
the cross-strap buckles 30, 31 to the outer strap 16. In
the Fig. 6c arrangement, a simple indent 84 is formed in
the back plate 34 of each buckle 30, 31. Since the cross-
strap 18 is not load sharing, it need be connected toouter strap 16 only sufficiently tightly that if the
entire assembly 10 (minus the climber) were hung on a
pole, the cross-strap 18 would hold the outer strap 16
reasonably tightly against the pole. The indents 84
require typically three to five pounds force to move them
from one hole 70 in the outer strap to the next. An
advantage of the Fig. 6c arrangement is that the climber
can adjust the position of the cross-strap 18 even while
wearing the usual heavy protection gloves.
In a preferred embodiment, the tooth 56 is
between 26 and 33 mm long and the barb 64 projects 3 to 6
mm from the surface of the tooth 48.
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It will be evident to those skilled in the art
that other embodiments of the invention fall within its
spirit and scope as defined by the following claims For
example, in some cases the safety device 20 can be made to
work without the rotational force of the spring 58. The
force generated by the edge of the barb 64 catching the
pole can be enough to extend the tooth 48 to the open
position 56 where it will bite into the pole 2. Alterna-
tively, different spring arrangements can be used, e.g.
tension springs, or two or more smaller and lighter coil
springs one or more on each side of the tooth 48, or
compression springs arranged to provide a downward force,
to keep the tooth normally latched and a rotational force
to help extend it once it is unlatched. These springs can
be internally positioned within housing 69. In addition,
while the barb 64 is shown as integral with the tooth 48,
a different arrangement can be used to unlatch the tooth,
e.g. a separate moving plate or barb which will catch the
pole and move so as to unlatch the tooth 48.
In place of balls 38, simple wear sleeves (e.g.
plastic or rubber hose or tubing) in short lengths may be
used. Alternatively, more but smaller balls can be used.
However it is preferred that these ba large enough to
provide space for the climber to insert his thumbs between
the cross-over strap 18 and the pole 2.
As shown in Fig. 8, buckles 30, 31 may each be
replaced by a buckle 30~ having a cam lever 100 which when
rotated about pivot shaft 102 forces a toothed cam 104
against outer belt 16, to prevent relative movement
between buckle 30' and belt 16. (This kind of arrangement
is conventional.) In addition, cross-over strap 18 may
have T-shaped end pieces 106 (Fig. 9) which fit into T-
shaped slots 108 in bosses 110 on the inner surfaces of
buckles 30', to hold the cross-over strap 18 to the outer
strap 16. Again, this type of connection is conventional.
End pieces 106 could of course be ball-shaped instead of
T-shaped.
