Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02378208 2002-03-21
TEM Docket No. 23 5.1
TITLE: IMPROVED CABLE PULLING DEVICE
s FIELD OF THE INVENTION
The present invention relates to cable pulling devices, and in particular
relates to a
winch assembly capable of pulling cable at selected speeds and torques.
BACKGROUND OF THE INVENTION
to A variety of cable pulling systems exist fur various purposes. Some
existing
systems use collets to grip and release a cable in order to pull it through a
pipe. These
prior systems suffer from several disadvantages. 'The pulling force typically
can not be
adjusted. Each device has one set pulling capacity, so that if a greater or
lesser pulling
force is required, then a stronger or weaker device must be substituted. In
current systems
15 the cable that is pulled through the pipe is not neatly stored, but is
simply left laying on
the ground. Furthermore, the cable is often damaged when gripped by a collet.
Other winch systems employ planetary drives that loose some of their pulling
capacity as coiled cable is layered outwardly on a drmn, resulting in a loss
of mechanical
advantage. Hence, a "30 ton" winch may have only 20 tons of actual pull left
by the time
2o the cable is fully spooled on the drum.
Alternate winch designs have been proposed in prior patents, each having their
shortcomings. US patent 3,698,690 to Beaver proposes a winch having two
hydraulic
motors for driving a drum. Both motors are controlled by a hydraulic fluid
supply system
which purports to place the hydraulic motors "in series" or "in parallel". The
claim is
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inaccurate in that a hydraulic motor's output torque varies directly with the
hydraulic
pressure drop across the motor, and so if the first hydraulic; motor uses most
of the
available pressure-drop, then the useful work performed by the second motor is
low or
negligible. Hence, the motors are not truly in series in that bath are not
performing the
s same amount of work.
US Patent 3,531,087 to Wilson discloses a winch drum having circumferentially
spaced ratchet teeth on each side. A fluid actuated cylinder and lever
arrangement
operates the drum by walking the levers alternately back and forth on the
respective
ratchet teeth. One lever is always engaged with the drum for rotation as the
other lever is
1o disengaged and being retracted to avoid recoil of the drum. The disclosed
device is
capable of providing the drum with only one speed and power setting.
What is therefore desired is a novel cable pulling device which overcomes the
limitations and disadvantages of the existing designs. Preferably, the cable
being pulled
should not be gripped and damaged as in some prior art machines. Further, the
novel
is device should provide for a pulling capacity and speed of the driven drum
that can be
selected between two settings. In a first setting, hydraulic cylinders should
be able to
perform similar work in unison to maximize pulling capacity. In a second
setting, the
cylinders should be capable of engaging the cogs in an alternating manner to
increase the
pulling rate but at a reduced pulling force. 1-Ience, the novel device should
provide a
2o choice of two speeds and two pulling forces, preferably at about the same
cost as prior
device with only one speed and pulling force.
SUMMARY OF THE PRESENT' INVENTION
In a preferred aspect the invention provides:
2s a frame portion adapted to be fixed to a support structure;
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a drum portion rotatably mounted to the frame portion for winding the cable
thereon, the drum portion including opposed first and second flanges;
hydraulically operated first and second cylinders pivotally mounted to the
frame
portion wherein the first cylinder is aligned to operatively engage the first
flange and the
second cylinder is aligned to operatively engage the second flange;
a brake mechanism mounted to the frame portion for releasably engaging the
drum portion to avoid recoiling of the drum portion when the cable is being
pulled; and,
a control means for delivering hydraulic fluid to the first and second
cylinders to
selectively provide at least a first power setting wherein the cylinders
operate in unison to
1o rotate the drum portion and a second speed setting wherein the cylinders
operate in
tandem to allow for faster rotation of the drum portion but at a reduced
pulling capacity
than in the first power setting.
DESCRIPTION OF THE DRAWING FIGURES
is Embodiments of the invention will now be described, by way of example only,
with reference to the accompanying drawings, wherein:
Figure 1 a shows a side view of a cable pulling device according to a
preferred
embodiment of the present invention with the piston in a fully retracted
position and a
brake mechanism engaged with the drum of the device;
2o Figure 1 b is a view similar to fig. l a but showing the piston contacting
the drum in
a partially extended position;
Figure lc is a view similar to fig.lb but showing the piston in a fully
extended
position;
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Figure 2 is a plan view of the device of figure 1 a; and,
Figure 3 is a side view of the device (cable omitted) in a free wheel mode
where
the cylinder is shown pivoted to a rest position and the brake mechanism is
disengaged
from the drum.
LIST
OF
REFERENCE
NUMERALS
IN
DRAWINGS
winch
12 cable
14 cable spooled on drum
10 16 longitudinal axis
drum
22 hub
24 flanges
26 axle
1s 28 bolts
30a-30d
cogs
40 frame
42 brackets
44 apertures
20 46 rearward portion of 40
50 pawl / brake mechanism
52 one end of 50
53 knuckle of 52
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54 lug
56 spring
57 lever
58 attachment point
to 57
59 elbow of 57
60a,
60b
hydraulic
cylinders
62a piston of 60a
64a head of 62a
66 pin and saddle arrangement
68 transverse axis
70 first proximity
switch
72 second proximity
switch
74 couplers on 60a
76 source of hydraulic
fluid
78a,
78b
valves
80 controller
82 electronic connection
t:o 80
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DESCRIPTION OF PREFERRED EMBODIMENTS
The figures show a cable pulling device, referred to herein as a "winch",
(generally designated by reference numeral 10) having a drum 20 rotatably
mounted on a
frame 40. 1'he frame has opposed plate-like brackets 42 with one or more
apertures 44
s therein for fixing the frame to a larger support structure when pulling the
cable 12. A
biased brake 50 is also pivotally mounted to each flange for engaging the
drum, as
described later.
The drum 20 has a central hub 22 fixed between opposed flange portions 24. It
will be understood that the winch is generally symmetrical about the
longitudinal center
line 16, and so like reference numerals are used for like features on either
side of the line
16. One end of the cable 12 is fixed to the hub 22 in a known manner, and the
hub 22
serves to coil, or spool, cable thereabout (as indicated by 14) during
operation. The hub
rotates about an axle portion 26 which extends transversely beyond each flange
and is
adapted to be removably fixed at each end to the brackets 42, as by bolts 28.
The
is perimeter of each generally circular flange 24 comprises a series of evenly
spaced cogs 30
oriented uniformly as shown in the drawings.
A pair of hydraulic cylinders 60a and 60b are mounted to the fame 40, one on
each bracket 42. Referring to one side of the symmetrical arrangement, a rear
end of the
cylinder 60a is mounted to a rearwardly extending portion 46 of the frame, as
by a pin
2o and saddle arrangement 66 or the like, in a manner which allows pivoting
about the
transverse axis 68. The cylinder 60a is aligned with the flange 24 to allow
the cylinder's
extendible piston 62a to engage the cogs 30 to rotate the drum. The cylinder
has two
connectors, namely couplers 74, for establishing fluid communication with a
source of
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pressurized hydraulic fluid 7fi, also referred to as a "power pack". The fluid
source 76
incorporates two valves 78a and 78b, one for each cylinder 60a and 60b,
respectively,
which are electronically manipulated by a controller 80 (preferably mounted on
the power
pack) to supply fluid to each cylinder independently. Hence, cylinder 60a is
controlled
s and supplied with fluid via its dedicated valve 78a independently of
cylinder 60b which is
controlled via the second valve 78b.
In use, pressurized hydraulic fluid is applied to the cylinder 60a to force
its piston
62a outwardly from a first, fully retracted, position (as shown in fig.l a) to
a second,
partially extended, position (shown in fig.lb) to engage a first cog 30a. The
piston is then
so pushed out to a third, fully extended, position (shown in fig.lc) to rotate
the drum in a
clockwise direction about the axle 26. 'the piston is then brought back to the
first fully
retracted position before engaging another cog to begin another cycle. During
retraction
from the fully extended position, the piston's head 64a disengages the cog 30a
by sliding
back along the inclined spine 32 of the rearwardly adjacent cog 30b, thus
pivoting the
s5 cylinder 60a about the axis 68 outwardly away from the drum (i.e. in a
counter-clockwise
direction in frg. l c) to allow full retraction of the piston. 'The cylinder
is then urged by
gravity to pivot clockwise to return to the fig. l a orientation in alignment
with the next
cog to be engaged. If need be, a biaser may be provided to urge clockwise
rotation of the
cylinder.
2o During the retraction portion of the cycle when the piston is disengaged
from the
cogs 30, the drum is stopped from recoiling by a brake mechanism in the form
of a pawl
50. A first end 52 of the pawl is pivotally mounted to the frame's bracket 42,
and a
second distal end of the pawl has a transversely protruding lug 54 adapted to
engage the
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cogs 30. The lug 54 is biased into contact with the cogs by a spring 56 which
urges the
pawl to pivot upwardly (clockwise when viewed in fig. l a) toward the drum.
One end of
the spring 56 is secured to a knuckle 53 protruding from the pawl's first end
52 in a
direction away from the lug ~4, and the other end is secured at 58 to a lever
57 which is
s pivotally engaged at elbow 59 to the frame 40. With the lever in a lowered
"over-centre"
position as shown in fig. l a, the spring 56 is in tension to urge the lug of
the pawl 50
toward the drum. When a user manually raises the lever 57, the bottom end 58
of the
lever pivots counterclockwise (as viewed in fig.3) about the elbow 59 to
release tension
on the spring 56, thus allowing gravity to urge the pawl to fall away from the
drum and
1o rest on the frame below out of engagement with the cogs. It will be
appreciated that in
the embodiment shown the drum must be rotated slightly in a clockwise
direction (in
fig. l a) to allow the lug to fully exit a cog and fall away fiom the drum.
In the configuration shown in fig. l a, the pawl's lug 54 is engaged with a
cog 30c
to prevent the drum from recoiling in a counter-clockwise direction when the
piston 62a
1s is being retracted toward the cylinder 60a and is disengaged with the drum.
Upon the
piston re-engaging a cog and rotating the drum in a clockwise direction, the
lug 54 merely
exits the cog 30c by riding out along the spine of adjacent cog 30d. It will
be appreciated
that the drum must recoil slightly (counterclockwise in fig. l a) for the lug
54 to fully
engage a cog. Although a brake mechanism comprising a single pawl arrangement
may
2o be sufficient for function of the winch, a pawl is preferably located on
each side of the
drum to avoid eccentric forces on the winch.
First and second proximity switches 70, 72 on each cylinder 60a, 60b
communicate with the contrc>ller 80 via electronic connection 82 to control
the stroke
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patterns of the individual cylinders by manipulating the delivery of
pressurized hydraulic
fluid via the electronically controlled valves 78a and 78b . An important
aspect of the
winch of the present invention, and its advantage over prior art winches, is
its ability to
operate in two modes. In a first "power" setting hydraulic fluid is delivered
to the
cylinders to work the cylinders in unison so that each piston 62a and 62b
simultaneously
engages and pushes the cogs on respective flanges, thereby maximizing the
winch's
pulling capacity. Both cylinders are preferably worked a like amount. Each
time the
pistons 62a, 62b disengage the cogs on a return stroke, the brakes 50 hold the
drum in
place and prevent recoil until the pistons begin another pushing stroke to
further wind the
1U cable.
In a second "speed" setting the control is switched for delivery of hydraulic
fluid
to the cylinders to engage the cogs in an alternating, or "tandem", manner. As
one of the
pistons engages and pushes a respective cog to rotate the drum, the second
piston is
retracted on a return stroke in preparation for engaging a cog upon the first
piston
i5 reaching its fully extended position. If the pistons are calibrated
properly, then the brake
will hardly be used since the second piston should begin pushing the drum as
the first
piston starts to retract. Hence, unlike the first setting where there is a lag
time during
which the drum does not rotate as both pistons are retracted, the pistons in
the second
setting "walk" back and forth on the drum to continuously turn the drum,
although not
2o necessarily at a uniform rate.
In an example of a typical operation of one embodiment of the winch, the
"power"
setting is adapted to provide a pulling force of about 30 tons on the cable 12
at a pulling
rate of about 4 feet/minute (approx. 1.2 m/min. j. In contrast, the same winch
in the
CA 02378208 2002-03-21
"speed" mode increases its pulling rate to about 7 feet/minute (approx. 2.1
m/min.), but at
a reduced pulling capacity of 15 tons since only one cylinder at a time is
actively rotating
the drum. The ultimate pulling capacity of the winch in its power mode and its
maximum
pulling speed in the speed mode will depend on the type of cylinders used and
the
dimensions of the drum.
The present winch may also be operated in reverse to release tension on a
cable
that has been pulled. 'The spring tension on brake 50 must first be released
by raising the
lever 57 as described earlier. A user operated remote (not shown) is then
employed to
override the winch's computer control and manually operate the cylinders 60a,
60b to
1o appropriately reverse delivery of fluid and walk the cylinders backwards
(i.e.
counterclockwise in fig.lc). 'Typically the tension should be fully released
on the cable
within a circumferential distance equivalent to 1 to 2 cogs, namely within one
piston
stroke from its fully extended position (fig. l c) to the retracted position
shown in fig. l b.
With the brake disengaged arid the cable tension released, the drum is in a
"free-wheel"
15 mode as shown in fig.3. In the free-wheel mode the cylinder 60a may, if
desired, be
advantageously pivoted about the pin 66 away from the drum to provide
unobstructed
access for handling the drum and cable.
Another advantage of the invention is that the cable is not gripped by any
means
along its length during either a coiling or uncoiling operation, thus avoiding
unecessary
2o wear and/or damage to the cable.
Yet another advantage is the ability to set the hydraulic pressure below the
bursting strength of the cable to avoid snapping the cable when puling,
particularly
underground.
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The above description is intended in an illustrative rather than a restrictive
sense,
and variations to the specific configurations described may be apparent to
skilled persons
in adapting the present invention to other specific applications. Such
variations are
intended to form part of the present invention insofar as they are within the
spirit and
s scope of the claims below. For instance, the rate of rotation of the drum in
either the
power or speed settings may bc: controlled by varying the rate of delivery of
pressurized
hydraulic fluid to the cylinders. Hence, the rate at which cable is pulled may
be varied
somewhat in each of the power and speed settings.
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