CA2378208A1 - Improved cable pulling device - Google Patents

Abstract

A device for pulling a cable may be operated in both a power mode and a speed mode. In particular, the device has a frame fixable to a support structure and a drum rotatably mounted to the frame for coiling the cable. Two hydraulic cylinders are pivotally mounted to the frame, each one operatively engaging an opposed side of the drum. A brake mechanism is mounted to the frame and is adapted to operatively engage the drum to prevent recoil when the cabel is pulled. A controller controls delivery of hydraulic fluid to the cylinders and may be operated to switch the device between a power mode where both cylinders operate in unison to provide maximum torque for pulling the cable, and a speed mode where the cylinders operate in tandem to increase the rate of pull on the cable but at a reduced torque.

Description

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 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;
L -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;

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 _q_ 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 _5_ 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 _6_ 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 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 _g_ 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 "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.

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.

Claims

We claim:

1. A device for pulling a cable comprising:
a frame portion adapted to be fixed to a support structure;
a drum portion rotatably mounted to said frame portion for winding said cable thereon, said drum portion including opposed first and second flanges;
hydraulically operated first and second cylinders pivotally mounted to said frame portion wherein said first cylinder is adapted to operatively engage said first flange and said second cylinder is adapted to operatively engage said second flange;
a brake mechanism mounted to said frame portion for releasably engaging said drum portion to avoid recoiling of said drum portion when said cable is pulled; and, a control means for delivering hydraulic fluid to said first and second cylinders to selectively provide at least a first setting wherein said cylinders operate in unison to rotate said drum portion and a second setting wherein said cylinders operate in tandem to allow for faster rotation of said drum portion than in said first setting.