Apparatus for defining a passageway through a composition

An apparatus for defining a passageway through a composition between first and second locations. The apparatus has a cable pulling assembly and a support for the cable pulling assembly. The cable pulling assembly has a capstan assembly, with a part of the capstan assembly guided in movement around a first axis and engageable with a cable connected to a mole so as to cause a cable engaged by the part of the capstan assembly to be pulled as the part of the capstan assembly is driven around the first axis. The part of the capstan assembly has a circumferential groove, bounded by a surface and extending around the first axis, for reception of a cable to be pulled. The groove is configured so that a circumferentially localized force is applied by the groove surface to a cable operatively positioned in the groove tending to avoid circumferential slippage between the part of the capstan assembly and the cable operatively positioned in the groove.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to cable pulling systems and, more particularly, to a system for drawing a mole through a composition to create a passageway between first and second spaced locations.

2. Background Art

It is well known in the industry to draw a mole through a composition to define a passageway through the composition between first and second spaced locations. It is known to use this method to replace collapsed conduits, such as those used for sewage, or for other applications. To carry out this process, access space is required at each of the first and second locations. A cable is directed from the second location through the existing conduit back to the first location at which the cable end is connected to an appropriately configured mole. The mole is engaged with a length of a replacement conduit in such a manner that the conduit will follow translatory movement of the mole. At the second location, a cable pulling mechanism is employed. The cable pulling mechanism, which is commonly hydraulically actuated, is braced against the composition and operated to draw the mole through the composition from the first location to the second location. The operator, who is situated at the second location, must monitor the advancement of the mole and disable the cable pulling mechanism at the appropriate time to prevent the mole from detrimentally contacting any part of the cable pulling mechanism and/or its support structure.

One known cable pulling mechanism is disclosed in U.S. Pat. No. 6,305,880. In that mechanism, the mole is advanced, through repeated pulling strokes, over its entire travel path between the first and second locations. In a typical pulling cycle, the mole will be advanced on the order of four inches. Each successive cycle must be initiated by an operator. While this system has been commercially successful, it has a number of inherent drawbacks.

First of all, as a result of the stepwise application of the pulling force, the mole, and following conduit, come to rest each time the mechanism is at the dwell stage for a pulling cycle. As this occurs, the stationary mole and conduit may become temporarily lodged before the pulling force can be reapplied thereto. To reinitiate movement of the mole, a greater force may be required than would be if the mole movement were not interrupted. This places greater demands on the cable pulling structure, the cable, the mole, the conduit, and the structure operatively connecting the mole to the cable and conduit. As a result, there is the potential for premature failure of one or more of these components and a potential reduction in the anticipated life of the overall system.

To address this problem, the system components may be made with increased capacity to ensure reliable operation and an adequately long life for the equipment. This may significantly increase the overall system costs which may have to be passed on to the system purchaser.

Another problem with the above prior art system is that the cable pulling mechanism is required to have potentially a large number of components to coordinatingly interact to alternatingly apply and release the pulling force on the cable. Generally, the more complicated systems become, the more prone they are to malfunction. Further, complicated systems are inherently more expensive than their simpler counterparts.

Still further, the above system has the drawback that the process for moving the mole between the first and second locations may be time consuming by reason of the stepwise advancement of the mole. These types of systems are generally designed to advance a mole through relatively dense compositions that offer a high resistance to movement of the mole. In some environments, such as in loose soil or a preexisting passageway, a significantly lesser resistance to mole movement may be encountered. However, the system operator is nonetheless required to operate the system in the same manner, initiating each advancing cycle, so that the mole moves at a relatively slow rate from the first location to the second location. Since these systems may require two or more individuals to set them up and monitor their operation, the number of man hours required to complete a job may be significant.

To the knowledge of the inventors herein, the industry has not utilized a cable pulling mechanism that is operable to continuously exert a pulling force on a mole to form or enlarge a passageway through a composition, as described above. Even had the industry looked in this direction, as a practical matter there has been lacking a compact unit with the required cable pulling capabilities that could be transported to different sites.

At some sites, the unit is required to be set up for operation underground or otherwise in a restricted space. In these tight quarters, a continuous cable pulling mechanism represents a particular challenge to designers. With a conventional capstan configuration, a V-shaped groove is formed continuously around an annular element that is driven around an axis. The surface bounding the groove and cable are relatively configured and dimensioned so that the cable wedges into the groove surface. This wedging action produces a traction force that causes the cable to follow movement of the annular capstan element around the axis.

Typically, capstans are made with a groove with a uniform cross-sectional configuration around the entire circumferential extent thereof. A cable to be pulled is wrapped around the capstan within the groove so that the center line of the wrapped cable resides in a single plane that is orthogonal to the rotary axis for the annular capstan element. The magnitude of the traction force is dictated by the degree of wrapping of the cable around the capstan. The cable is typically wrapped through significantly less than 360° around the capstan so that there is no interference between the cable at locations at which it initially contacts the capstan and departs therefrom.

The traction force may be increased by increasing the diameter of the capstan so as to increase the contact area between the annular capstan element and the wrapped cable. However, given typical space constraints, there are limitations placed on the dimensions of the capstan.

An alternative way to increase the contact area between the cable and capstan is to cause wrapping through in excess of 360° around the capstan. This requires the formation of a spiral groove pattern on the annular capstan element. As a result, the axial dimension of the capstan increases, as does potentially the cost of the capstan manufacture. Additionally, the use of multiple turns of cable on a capstan causes complications for the system operator. The operator must manipulate the cable around the capstan in a manner that may be inconvenient or impractical in quarters that are close. Further, the inherent stiffness of a cable may make it difficult to produce the multiple wraps and to maintain the cable in the groove in a proper manner preparatory to startup.

Designers of this type of system strive to devise portable systems that can be economically manufactured, will reliably perform in potentially severe environments, can be conveniently and efficiently set up, operated, and broken down, and will perform reliably for an adequate -lifetime. In the interest of economy, it is also a goal for designers of these systems to avoid the unnecessary expenditure of man hours for their operation.

SUMMARY OF THE INVENTION

In one form, the invention is directed to an apparatus for defining a passageway through a composition between first and second locations. The apparatus has a cable pulling assembly and a support for the cable pulling assembly. The cable pulling assembly has a capstan assembly, with a part of the capstan assembly guided in movement around a first axis and engageable with a cable connected to a mole so as to cause a cable engaged by the part of the capstan assembly to be pulled as the part of the capstan assembly is driven around the first axis. The part of the capstan assembly has a circumferential groove, bounded by a surface and extending around the first axis, for reception of a cable to be pulled. The groove is configured so that a circumferentially localized force is applied by the groove surface to a cable operatively positioned in the groove tending to avoid circumferential slippage between the part of the capstan assembly and the cable operatively positioned in the groove.

The apparatus may be provided in combination with a cable and a mole attached to the cable.

In one form, the groove extends continuously around the first axis.

In one form, the groove has an axial center and the axial center of the groove at a first circumferential location is spaced axially from the axial center of the groove at a second circumferential location.

In one form, the groove has a circumferential extent and the axial center of the groove has a curved shape over at least a portion of the circumferential extent of the groove.

The axial center of the groove may have a wave shape over at least a portion of the circumferential extent of the groove.

In one form, the groove surface defines an axial projection which causes the circumferentially localized force to be applied to a cable under tension within the groove.

In one form, the groove surface has axially spaced side portions which converge to a radially opening bottom portion and the axial projection is defined by one of the axially spaced side portions.

The groove may extend in a spiral pattern around the first axis.

In one form, the cable pulling assembly has a drive and a gear assembly operatively engaged between the drive and the part of the capstan assembly to cause the part of the capstan assembly to be driven around the first axis.

The gear assembly may be a planetary gear assembly.

The invention is further directed to an apparatus for defining a passageway through a composition between first and second locations, which apparatus has a cable pulling assembly and a support for the cable pulling assembly. The cable pulling assembly has a capstan assembly, with a part of the capstan assembly guided in movement around a first axis and engageable with a cable connected to a mole so as to cause a cable engaged by the part of the capstan assembly to be pulled as the part of the capstan assembly is driven around the first axis. The part of the capstan assembly has a circumferential groove, bounded by a surface and extending around the first axis, for reception of a cable to be pulled. The groove extends continuously around the first axis and has an axial center. The axial center of the groove at a first circumferential location is spaced axially along the part of the capstan assembly from the axial center of the groove at a second circumferential location.

The apparatus may be provided in combination with a cable and a mole attached to the cable.

In one form, the groove has a circumferential extent and the axial center of the groove has a curved shape over at least a portion of the circumferential extent of the groove.

In one form, the axial center of the groove has a wave shape over at least a portion of the circumferential extent of the groove.

In one form, the groove surface defines an axial projection which causes a circumferentially localized force to be applied to a cable under tension within the groove.

The groove surface has axially spaced side portions which converge to a radially opening bottom portion. In one form, the axial projection is defined by one of the axially spaced side portions.

In one form, the cable pulling assembly includes a drive and a gear assembly operatively engaged between the drive and the part of the capstan assembly to cause the part of the capstan assembly to be driven around the first axis.

The gear assembly may be a planetary gear assembly.

The invention is further directed to a cable pulling assembly having a capstan assembly having a part with a groove for receiving a cable to be pulled and a drive through which the part of the capstan assembly is driven around a first axis to cause a cable operatively positioned in the groove to be pulled. The groove has a circumferential extent around the first axis. The groove is configured so that a circumferentially localized force is applied by the groove surface to a cable operatively positioned in the groove, tending to avoid circumferential slippage between the part of the capstan assembly and a cable operatively positioned in the groove.

The cable pulling assembly may be provided in combination with a cable and mole which is connectable to the cable to follow movement of the cable through a composition to form a passageway in the composition.

The groove may extend continuously around the first axis.

In one form, the groove has an axial center, and the axial center of the groove at a first circumferential location is spaced axially along the part of the capstan assembly from the axial center of the groove at a second circumferential location.

In one form, the center of the groove has a curved shape over at least a portion of the circumferential extent of the groove.

The center of the groove may have a wave shape over at least a portion of the circumferential extent of the groove.

In one form, the groove is bounded by a surface and the surface defines an axial projection which causes the circumferentially localized force to be applied to a cable under tension within the groove.

In one form, the surface of the groove has axially spaced side portions which converge to a radially opening bottom portion and the axial projection is defined by one of the axially spaced side portions.

A gear assembly may be operatively engaged between the drive and capstan assembly part to cause the part of the capstan assembly to be driven around the first axis.

The gear assembly may be a planetary gear assembly.

The invention is further directed to a cable pulling assembly having a capstan assembly with a part with a groove for receiving a cable to be pulled and a drive through which the part of the capstan assembly is driven around the first axis to cause a cable operatively positioned in the groove to be pulled. The groove has a circumferential extent around the first axis. The axial center of the groove at a first circumferential location is spaced axially along the part of the capstan assembly from the axial center of the groove at a second circumferential location.

The apparatus may be provided in combination with a cable and mole that is connectable to the cable to follow movement of the cable through a composition to form a passageway in the composition.

The groove has a circumferential extent. In one form, the axial center of the groove has a curved shape over at least a portion of the circumferential extent of the groove.

The axial center of the groove may have a wave shape over at least a portion of the circumferential extent of the groove.

In one form, the groove is bounded by a surface and the surface defines an axial projection which causes a circumferentially localized force to be applied to a cable under tension within the groove.

In one form, the surface of the groove has axially spaced side portions which converge to a radially opening bottom portion and the axial projection is defined by one of the axially spaced side portions.

The cable pulling assembly may further include a gear assembly operatively engaged between the drive and the part of the capstan assembly to cause the part of the capstan assembly to be driven around the first axis. The gear assembly may be a planetary gear assembly.

DETAILED DESCRIPTION OF THE DRAWINGS

InFIG. 1, a representative environment is shown at10for the practice of the present invention. An apparatus, according to the invention, is shown at12for defining a passageway through a composition at14between a first location16and a second location18. The composition14may be any naturally occurring composition, a composition that is formed, as through construction, or the like, or a combination thereof. In this particular application, a collapsed conduit20, extending between the first and second locations16,18, is being replaced. The process for operating the inventive apparatus12will now be described with reference additionally to the flow diagram shown inFIG. 2.

Initially, a cable22is directed between the first and second locations16,18, as shown at block24. To accomplish this, the cable22can be directed from either the first location16to the second location18, or alternatively, from the second location18to the first location16. If the condition of the conduit20permits, the cable22may be directed therethrough without resistance. Alternatively, conventional means, known to those skilled in the art, may be utilized to direct the cable22between the first and second locations16,18. The invention also contemplates that the cable22could be directed between the first and second locations16,18without any preformed passageway, as defined by the conduit20, as by preforming a small passageway therefor, or by forcibly advancing the cable22through the composition between the first and second locations16,18. Again, those skilled in the art are familiar with conventional means that can be utilized to direct the cable22through the composition14between the first and second locations16,18, without any preexisting passageway.

At the first location16, a mole26is attached to the cable22, as shown at block28. In the event that the cable22is directed from the first location16towards the second location18, the mole26can be pre-attached to the cable22. Those skilled in the art are well versed in the selection of a mole to penetrate the specific composition14and generate an opening of the desired dimensions therethrough.

A conduit30is attached to the mole26, as shown at block32. An end of the conduit30is attached to the mole26to follow movement thereof as the cable22draws the mole26from the first location16to the second location18. Suitable connecting structures are also well known to those skilled in this art.

The cable22is then engaged with a cable pulling assembly34, as shown at block36. The cable pulling assembly34is carried on a support38. The cable pulling assembly34may be permanently mounted to the support38, but is more preferably separably mounted thereto, as explained in greater detail below. The support38bears against the composition14to transfer to the composition14a reaction force that is generated as the cable pulling assembly34draws the cable22between the first location16and the second location18. It should be understood that while the support38is described throughout as bearing against the composition14, it is also contemplated that the support38could bear against any other firm structure that may be integrated into the composition14, or separate therefrom. The description of the support38as bearing against “the composition14” hereinbelow is intended to encompass bearing against any firm structure.

The apparatus12is placed in an operative position at the first location18, as shown at block40. The apparatus12can be pre-assembled and directed downwardly in that state through an opening42to adjacent the second location18, or directed through the opening42in parts and assembled at the second location18, as hereinafter described.

As shown at block44, the cable pulling assembly34is operated by a user/operator46through a control48to exert a pulling force on the cable22, as indicated by the arrow50. The pulled cable22is then directed away from the cable pulling assembly34, as indicated by the arrow52, and may be accumulated at the second location18, or directed outwardly through the opening42.

The cable pulling assembly34may be continuously operated to cause a pulling force on the cable22to be continuously applied through the cable pulling assembly34to the cable22and therethrough to the mole26to thereby cause the mole26to be advanced in a travel path equal to the entire distance D between the first and second locations16,18, or at least a substantial distance D1that is less than the distance D. The distance D may be, for example, several feet up to potentially a hundred or more feet. It is contemplated that the mole26be moved under a continuously applied force through at least the substantially shorter distance D1, that is less than the distance D, but on the order of one foot or more.

Once the conduit30is drawn in a manner that a sufficient length thereof is exposed at the first and second locations16,18, the apparatus12, mole26, and cable22are separated from the conduit30, as shown at block54. The apparatus12, mole26, and cable22can then be removed from the site, as shown at block56. The apparatus12can be removed as a unit or broken down to facilitate removal and transportation in parts.

In the depicted environment10, the first and second locations16,18are shown underground. In this case, the conduit30can be drawn from a supply58thereof, above ground, to be advanced in following relationship with the mole26, between the first and second locations16,18. In this environment10, the operator/user46is likewise located underground. A vertical opening60can be formed to a sufficient diameter to allow the conduit30to be drawn from the supply58to be presented at the first location16, and drawn through the composition14from the first location16to the second location18, without damage thereto.

It should be understood that the invention is not limited to an underground application and can be used in any environment in which a mole, or other like leading structure, is to be drawn by a cable through a composition, with or without a partial or full passage opening. Further, it is not required that a conduit be drawn through the composition, as solid cable or other material could be connected to follow the movement of the mole, or the like, in the same manner, to extend the same between corresponding first and second locations.

Further, in the event that a conduit is advanced between the first and second locations, the nature of the conduit is not in any way limited. The conduit could be used to define a receptacle for cables, such as in the telecommunications industry, to communicate water, that may be fresh water or sewage, etc.

Referring now toFIGS. 3-5, one specific form of the inventive apparatus12is shown. The apparatus12consists of the cable pulling assembly34, which is mounted in an operative position on the support38. The support38consists of a frame64to which the cable pulling assembly34is releasably, operatively connected, a reaction plate66, and a reaction cage68acting between the frame64and reaction plate66. With the frame64, reaction cage88, reaction plate66, and reaction cage68assembled, a downwardly facing support surface at70is defined by coplanar surfaces on the frame64, reaction cage88, and reaction plate66. The frame64has a flat surface72, with the reaction plate66having flat surfaces74,76defined on horizontally projecting feet78,80, respectively, and flat surfaces82(one shown inFIG. 4) on horizontally projecting feet83(one shown inFIG. 4). A reference plane P, coincident with the surfaces72,74,76,82, is orthogonal to a plane P1that coincides with an enlarged, substantially flat surface84on the reaction plate66. With this configuration, the surfaces72,74,76,82can be placed against an upwardly facing surface86, as shown inFIG. 1. With the apparatus12supported in this manner, the reaction plate surface84can be braced against a vertically extending surface88on the composition14at the second location18.

The reaction plate66has an opening90through which the cable22can be drawn by the cable pulling assembly34. As the cable22is drawn by the cable pulling assembly34in the direction of the arrow92inFIG. 4, a reaction force is generated which is transferred from the cable pulling assembly34through the frame64, reaction cage58and reaction plate66to the composition14which, as previously discussed, may be an existing component or any other preexisting or added structure that is stable and sufficiently rigid to withstand the reaction force generated during operation of the cable pulling assembly34.

As depicted inFIG. 4, the cable22is drawn generally in the path indicated by the dotted line at94. The cable22moves through the opening90in the reaction plate66, through the reaction cage68, and a vertically extending wall96on the frame64, to engage an annular cable- engaging part98(FIG. 5) at approximately the 12 o'clock position thereon. The cable22wraps in a clockwise direction inFIG. 4around the cable-engaging part98and departs from the cable-engaging part98at approximately the 9 o'clock position thereon to be directed upwardly for appropriate accumulation as the cable pulling assembly34is operated. As explained in greater detail below, the cable-engaging part98is driven about an axis102to cause continuous advancement of the cable22in the aforementioned path, shown by the dotted line94inFIG. 4.

A drive/hydraulic motor assembly at104, in communication with a pressurized hydraulic fluid supply106, is operable to drive the cable-engaging part98around the axis102, as is also described in greater detail below. According to the invention, the drive/hydraulic motor assembly104can be continuously operated to cause the cable-engaging part98to continuously exert a pulling force on the cable22and therethrough to the mole26to cause the mole26to be advanced. The mole26is thus capable of being advanced a substantial distance under this constant pulling force. A “substantial distance”, as used herein, is intended to be on the order of a foot or more. More preferably, the entire distance to be traversed by the mole26through the composition14is travelled under a continuous force application through the cable22to the mole26. This obviates the incorporation of a conventional-type mechanism typically operated by applying and releasing a pulling force on the cable22. An actuator108, associated with the control48, is manually operable by the user/operator to control the drive/hydraulic motor assembly104. Thus, the user/operator has the ability to cause the pulling force to be applied on the cable22through the cable pulling assembly34continuously, or at desired intervals, to cause the mole26to be advanced a substantial distance under a constant pulling force. The drive/hydraulic motor assembly104can be continuously operated as the mole26moves fully from the first location16to the second location18.

A switch assembly110is provided to disable the drive/hydraulic motor assembly104and thereby stop operation of the cable pulling assembly34with the mole26advanced to a predetermined position relative to the cable pulling assembly34. Accordingly, the advancement of the cable22and the mole26will be automatically stopped so that no operator intervention is required to avoid drawing of the mole26against any part of the support38or cable pulling assembly34as might inflict damage thereon.

The apparatus12preferably has a modular construction which allows it to be transported in separate pieces and assembled on site. In this embodiment, the cable pulling assembly34, frame64, reaction cage68, and reaction plate66are formed as separable components.

Referring now additionally toFIGS. 6-8, the reaction plate66has a reinforced wall112through which the cable opening90is formed. The flat surface84is defined on one side of the wall112. Mounting tabs114,116,118,120project from the side of the wall112opposite that on which the surface84is defined. With the reaction plate66and reaction cage68in the assembled relationship shown inFIGS. 3-5, mounting tabs122,124,126,128on the reaction cage68situate adjacent to the mounting tabs114,116,118,120, respectively, to allow releasable locking pins130to be directed through bores in each of the adjacent, paired mounting tabs114,122;116,124;118,126; and120,128. The locking pins130substantially fix the reaction plate66and reaction cage68against relative fore and aft movement, along a line extending between left and right inFIG. 4.

As seen by reference additionally toFIGS. 9-12, the frame64and reaction cage68are releasably connectable in an operative state through a like cooperative arrangement of mounting tabs132,134,136,138on the reaction cage68and140,142,144,146on the frame64. Locking pins130extend through the paired mounting tabs132,140;134,142;136,144; and138,146to substantially fix the frame64and reaction cage68against relative fore and aft movement.

The reaction cage68has spaced walls148,150, each generally in the shape of the letter “A”. The wall148carries the mounting tabs122,124,126,128, with the wall150carrying the mounting tabs132,134,136,138. Tubular reinforcing elements152,154,156,158connect between the walls148,150to unitize the reaction cage68. The connection of each of the tubular reinforcing elements152,154,156,158to its respective wall148,150is reinforced by gussets160,162,164, as shown for the exemplary connection between the tubular reinforcing element156and the wall148. A reinforcing web166connects between the tubular reinforcing elements152,154and the walls148,150.

Through this arrangement, the reaction force generated during operation of the cable pulling assembly34is transmitted from the frame64to the wall150and from there through the tubular elements152,154,156,158to the wall148and to the reaction plate66, which distributes the force over the area to which the flat surface84on the reaction plate66abuts.

The frame wall96has a flat surface170, matched generally in shape to the “A” shape of the wall150on the reaction cage68, so as to transmit the reaction force over the area of the flat surface170on the wall168to an abutting flat surface172on the wall150over a substantial area. The wall148has a corresponding flat surface174which facially abuts to a flat surface176(FIGS. 4,6) on the reaction plate66, to distribute the reaction force over a substantial area of the reaction plate66.

As seen inFIG. 4, the reaction cage68defines a working space at178. Through the working space178, the user/operator can manipulate the cable22and conduit30during setup and operation of the apparatus12.

The frame64has a generally L-shaped construction defined by the vertically extending wall96, and a horizontally extending wall180. With the frame64and reaction68in assembled relationship, a tongue182on the reaction cage68situates beneath a downwardly facing edge184(FIG. 12) on the frame64. The cooperation between the tongue182and edge184facilitates alignment of the frame64and reaction cage68.

The frame walls96,180are reinforced by a pair of spaced, L-shaped mounting braces186,188which define a mounting space190therebetween for the cable pulling assembly34. Reinforcing gusseting192, for the exemplary mounting brace186, rigidifies the connection between the mounting brace186and walls96,180. The mounting brace188is similarly reinforced through gusseting at194.

The mounting braces186,188have the same construction. Exemplary mounting brace186has a horizontal leg196and a vertical leg198which are configured to cooperatively, releasably support a traction support assembly200, which is shown inFIGS. 13-15, and which defines a foundation for the operating components of the cable pulling assembly34. The traction support assembly200consists of traction support plates202,204that are joined, and maintained in spaced relationship, by a bottom pivot pin206and a separate bearing element/pin208adjacent the top of the traction support assembly200.

The traction support plates202,204are joined so as to cooperatively produce a combined width W (FIG. 14). The pivot pin206has a length that is greater than the width dimension W so that it defines stub shaft portions210,212projecting to beyond the walls202,204, respectively. The bearing pin208has a similar length to define stub shaft portions214,216, respectively extending to beyond the traction support plates202,204. The width W is slightly less than the width W1(FIG. 12) of the mounting space190between the mounting braces186,188to allow a portion of the cable pulling assembly34to be directed therebetween, as explained in detail below.

As seen additionally inFIG. 16, the mounting brace186has an upwardly opening, U-shaped receptacle218, with the mounting brace188having a like, upwardly opening receptacle218′. With the bottom portion of the traction support assembly200directed between the mounting braces186,188, the stub shafts210,212on the pivot pin206can be guided into the receptacles218,218′, respectively. The receptacles218,218′ have curved surfaces220,220′ which cooperate with the stub shafts210,212to guide pivoting movement of the pivot pin206around a horizontal axis222relative to the frame64.

With the traction support assembly200initially separated from the frame64, the traction support assembly200can be repositioned relative to the frame64to direct the stub shafts210,212downwardly into the receptacles218,218′ so that a preassembly position, as shown in solid lines inFIG. 16, is realized. The traction support assembly200is changed from the preassembly position into the operative position, shown inFIGS. 3-5and in dotted lines inFIG. 16, by pivoting movement around the axis222in the direction of the arrow224inFIG. 16. As this occurs, the stub shaft portions214,216on the bearing pin208move into U-shaped receptacles226,226′ in the mounting braces186,188, respectively. The bases of the receptacles226,226′ are defined by curved surfaces228,228′ which are complementary to the shape of the stub shaft portions214,216.

With the traction support assembly200in the operative position, a reaction force generated by operation of the cable pulling assembly34is caused to be simultaneously transmitted from the stub shafts210,212to the curved surfaces220,220′ bounding the receptacles218, and from the stub shafts214,216on the bearing pin208to the surfaces228,228′ bounding the receptacles226,226′. Through this arrangement, a reaction force generated during operation of the cable pulling assembly34is distributed to the frame wall64, at vertically and horizontally spaced locations, and from there to the wall150of the reaction cage68.

The cable pulling assembly34can be conveniently assembled to and separated from the frame64by practicing the steps described above. Accordingly, the cable pulling assembly34can be placed in its operative position, and maintained in the operative position, under its own weight without the requirement of separate fasteners, by merely relatively repositioning the cable pulling assembly34and frame64. Manipulation of the cable pulling assembly34is facilitated by the provision of a U-shaped handle230at the top of the traction support assembly200. The handle230has a base232(FIGS. 3 and 5) and spaced legs234,236extending from the base232. The legs234,236are connected, one each, to the stub shafts214,216on the bearing pin208.

Details of the cable pulling assembly34, consisting of the traction support assembly200, to which the operating components are mounted, will now be described with respect toFIGS. 17-30. An operating component package assembly, which is integrated into the traction support assembly200, is shown at240. The operating component package assembly240consists of the aforementioned drive/hydraulic motor assembly104, a capstan assembly at242, and a gear assembly at244, for transmitting a force from the drive/hydraulic motor assembly104to the part98of the capstan assembly242to cause the part98of the capstan assembly242to be driven around the axis102.

The capstan assembly part98has an annular shape with an outwardly opening, U-shaped groove246formed continuously therearound. The groove246is formed in a “wave” pattern fully around the axis102. In this embodiment, the wave pattern is regular throughout the circumferential extent thereof. It is not required that the pattern be regular or that there be a specific amplitude or length for each wave, as explained in greater detail below.

The theory of operation is as follows. In a conventional straight, non-wave groove, the cable22, under tension, is squeezed radially inwardly into the groove and against a U-shaped surface bounding the same. The traction force between the cable22and abutting groove surface is substantially uniform along that portion of the groove surface that is engaged by the cable22. This force is generated through a wedging action as the cable22is drawn radially inwardly.

By using the wave pattern, the cable is caused to bend to nominally match the wave pattern. As the tension on the cable22increases, the cable22tends to straighten, which causes a localized pressure increase between the cable22and peaks248in the groove shape defined by the wave pattern, thereby enhancing the traction force on the cable22. The amplitude of each “wave” is thus selected to cause the generation of localized, increased pressure points, throughout the contact length, between the cable22and the capstan part98at the peaks248.

The cable diameter and flexibility will determine the appropriate amplitude and frequency for each wave. At too great an amplitude and too short a wavelength, it may be difficult to conform the cable22to the groove shape. A reduced wavelength and increased amplitude may also result in the cable22not properly seating to the desired depth in the groove246to benefit from the wedging action along the length. As shown inFIG. 28, this wedging action of the cable22in the groove246is primarily responsible for the gripping between the cable22and capstan part98. If the wavelength becomes too long, and the amplitude too small, the operating characteristics approach that of a conventional, straight, non-wave groove.

The design also must take into account the fact that as the cable22is placed under tension, its effective diameter reduces, as depicted inFIG. 29, whereby the tensioned cable22seats more deeply into the groove246. Thus, at the reduced diameter, it is desired that there still be a relationship between the cable22and groove246that permits the requisite wedging action as the cable22is pulled in operation.

A typical cable diameter for this application is on the order of 0.75 inch. However, this is a common diameter used in the industry and should not in any way be viewed as limiting. If properly designed, as explained in greater detail below, the wave groove may account for a substantial increase in traction force over conventional grooves, potentially achieving traction forces similar to those resulting from multiple wraps of the cable22.

The capstan assembly242has a ring gear/annulus250with an annular arrangement of inner gear teeth252thereon. The annulus250is drivingly engaged by the gear assembly244, which in turn is driven by the drive/hydraulic motor assembly104. More specifically, the gear assembly244is a planetary gear assembly consisting of a sun gear254and a plurality, and in this case five, planet gears256. The number of planet gears256could be as few as two or greater than the five shown. The drive/hydraulic motor assembly104has an externally toothed output258(FIG. 30) which is keyed within a socket260on the sun gear254so that the sun gear254follows rotational movement of the output258around the axis102.

The sun gear254has two axially spaced, annular arrays of external teeth at262,262′, which are in mesh with corresponding annular arrays of external teeth264,264′ on each planet gear256. The teeth264,264′ are in turn in mesh with internal teeth268,268′ on annular ground gears270,270′.

With the sun gear254driven in the direction of the arrow272inFIG. 22around the axis102, the planet gears256are caused to be rotated about their respective axes274in the direction of the arrows276. As seen primarily inFIGS. 21 and 26, as the planet gears256move around their axes274, an annular array of external teeth at278on each planet gear256, between the teeth264,264′, are in mesh with the teeth252on the annulus250, and drive the annulus250with the integral cable-engaging part98around the axis102in the direction of the arrow280.

The connection of the operating component package assembly240to the traction support assembly200will now be described. A traction base288is placed against an annular, axially facing surface290(FIG. 23) on the capstan part98. The traction base288has an annular rim92with an axially facing, annular surface294. The annular surface294defines a seat for a ball bearing assembly296with roller elements298that act between a radially inwardly facing surface300on the traction base288, and a radially outwardly facing surface302on the capstan part98.

A cover assembly308is then installed. The cover assembly308has a first cover part310that is secured by fasteners312to the traction base288. A second cover part314on the cover assembly308is in turn secured to the first cover part310through fasteners316. Appropriate sealing elements, such as those shown at317inFIG. 20, and well known to those skilled in the art, can be interposed between the components. The detail of these sealing elements will not be described herein.

The traction base288has a peripheral edge318which is generally in the shape of a triangle with three rounded apices320. The traction support plate202on the traction support assembly200has an opening322formed therethrough that is nominally matched to the shape of the peripheral edge318. The traction support plate202has formed receptacles at324, each designed to receive one of the apices320on the traction base288. Each receptacle324is bounded by a curved surface326which converges towards the center328of the opening322. The traction base288is directed into the opening322in an axial direction to bring the apices320into contact, one each, with the surfaces326at each receptacle324. By urging the surfaces326and traction base288axially against each other, a centering/wedging action is produced therebetween so that the traction base288and traction support plate202become preliminarily held against relative pivoting around the axis102. A more positive keying against relative pivoting movement is achieved by reason of the matching triangular shapes of the traction base peripheral edge318and the opening322in the traction support assembly200. With the traction base288preassembled in this manner, mounting clips330can be attached to the traction support plate202to loosely, captively, maintain the traction base288in a preassembly position relative to the traction support assembly200.

The traction support assembly200can then be reoriented with the loosely held traction base288. The mounting clips330prevent the traction base288from axially separating from the traction support assembly200as this occurs. For convenience of assembly the traction support assembly200can be oriented with the traction base288held loosely thereto, so that the traction support plate202faces downwardly.

The remaining components are assembled from the side of the traction support plate204to captively embrace the traction support assembly200. More specifically, a corresponding traction base288′, ball bearing assembly296′, first cover part310′, sealing element317′, and second cover part314′ are sequentially installed, in the same manner as the corresponding parts on the other side of the traction support assembly200, as previously described.

The traction support plate204has a construction corresponding to the traction support plate202, with receptacles324′ around an opening322′ to receive apices320′ on the traction base288′. The receptacles324′ have surfaces326′ corresponding in shape and function to the surfaces326.

With the operating component package assembly240fully assembled around the traction support assembly200, the surfaces326,326′ are captive between the traction bases288,288′. At the same time, the operating component package assembly240is confined against relative rotation around the axis102by reason of the keyed connection between the peripheral edge318of the traction base288within the opening322and a like keying arrangement between a corresponding peripheral edge318′ on the traction base288and a corresponding opening322′ on the traction support plate204.

Another aspect of the present invention is the provision of a cable tensioning assembly, as shown at332inFIGS. 9-12. The cable tensioning assembly332includes a cantilevered support334which carries, at its free end, a roller336for movement about a horizontally extending axis338. The roller336is aligned with the groove246in the capstan part98. As the cable pulling assembly34is pivoted from the preassembly position, shown in solid lines inFIG. 16, to the operative position, the roller336moves into the groove246at approximately the 8 o'clock position inFIG. 4. During operation, the roller336acts against the cable22to locally urge the cable22radially inwardly into the groove246to enhance the traction force production on the cable22by the capstan part98. As the cable tension is increased, the cable pulling assembly34is pressed with an increasing force towards the roller336to increase the force produced by the roller336on the cable22.

With the apparatus12set up, the cable22, having the mole26attached thereto, is directed through the reaction plate66, the reaction cage68, and an opening340(FIG. 12) in the frame64. The cable22is wrapped in the pattern shown inFIG. 4around the capstan part98beginning at the 12 o'clock position and extending through 270° to approximately the 9 o'clock position, whereat the cable departs from the capstan part98and projects vertically upwardly for appropriate accumulation, at a location which is above ground in theFIG. 1arrangement. By manipulating the actuator108on the drive/hydraulic motor assembly104, valving on a valve block assembly342is placed in a state to cause driving of the output258, which thereby actuates the planetary gear assembly244to rotate the capstan part98around the axis102. The drive/hydraulic motor assembly104can be continuously operated to produce a constant pulling force on the cable22to cause the mole26to move a substantial distance D1through the composition14, and preferably the entire distance D between the first and second locations16,18. The switch assembly110will automatically cause a bypass valve to divert flow of the hydraulic fluid at the valve block342to interrupt the pulling force once the mole26has reached a predetermined position.

It should be understood that the above structure is exemplary in nature only. The invention contemplates modifications to all different aspects of the structure disclosed.

As just one example, the receptacles218,218′, shown on the frame64, could be formed on the cable pulling assembly34, to cooperate with an appropriate projection on the frame64to allow the requisite relative pivoting movement between the frame64and cable pulling assembly34.

As shown inFIG. 31, and previously explained, the wave pattern for the groove246on the cable-engaging capstan part98, which is shown in an exaggerated form inFIG. 31, is regular and repeats throughout the entire circumferential extent of the groove246. The wave pattern is shown with a wavelength (WL) and amplitude (A), with the amplitude measured from a reference plane P, axially bisecting the groove246and orthogonal to the axis102, to the center line CL of the cable22, which is shown conformed to the contour of the groove246along the circumferential extent thereof, depicted inFIG. 31.

The cable22is initially directed into the groove246and conformed to the sinusoidal shape thereof. In operation, the cable22, under tension, tends towards a straight length along a line orthogonal to the axis102. This bears the cable22axially relative to the axis102against the aforementioned peaks at248whereby a circumferentially localized force, as indicated by the arrows F, is applied at each peak248to the cable22.

As seen inFIGS. 28 and 29, the groove246is defined by a U-shaped surface360having axially spaced side portions362,364which converge to a radially opening bottom portion366. The circumferentially localized forces at the peaks248are applied to the cable22through the side portions362,364.

As previously noted, the wave pattern can be defined uniformly over the entire circumferential extent of the cable-engaging capstan part98. However, myriad different groove configurations are contemplated. The only critical aspect of the groove configuration is that the tendency of the cable22to straighten, as it is placed under tension, will produce a circumferentially localized pressure area or point on the cable22that causes an enhanced traction force to be developed between the capstan part98and cable22. Generally, this will result with any groove configuration in which the cable22is caused to change direction appreciably over a relatively limited circumferential length. As a result, the centerline (CL) of the groove246has different circumferential locations that are spaced differently, in an axial direction, along the capstan part98, from the same reference plane P, as opposed to a conventional groove, wherein the center line resides substantially in a single plane. At each such location, such as at the peaks248, the axial force component F is applied to the cable22. If a localized force is generated at more than one circumferential location, the effect on the traction force between the capstan part98and cable22is cumulative.

InFIG. 32, a modified form of cable-engaging capstan part98′ is shown with a groove246′ having a curved portion at368. The curved portion368may repeat around the circumference of the cable-engaging capstan portion98′. Alternatively, only one such curved portion368may be provided. As a further alternative, the curved portion368may be provided in more than one location but not in a regular pattern around the circumference of the cable-engaging capstan portion98′. With the groove construction shown, a peak248′ is defined so that the side portion362′ of the groove surface360′ produces a localized axial force F on the cable22in the groove246′.

InFIG. 33, a groove246″ is shown having a curved portion at368′, corresponding to the curved portion368, but wherein the cable22, operatively in the groove246″, is required to change directions more abruptly thereat. More specifically, the peak248″ has a smaller radius which produces more of a pinching action in an axial direction on the cable22through the force F. Additionally, whereas the groove248′ is continuously curved over a substantial circumferential extent on the cable-engaging capstan part98′, the curved portion368′ on the capstan part98″ extends over a lesser circumferential length and is located between groove portions370,372which are substantially straight and parallel to the travel direction, as indicated by the double-headed arrow374. The travel direction is parallel to the reference plane P, corresponding to that inFIG. 31.

The groove246′″ inFIG. 34on the capstan part98′″ corresponds generally to the configuration of the groove246″ inFIG. 33with the exception that the curved portion368″ is approximated by an arc with a larger radius than that of the arc that approximates the curved portion368′. The force F produced on the cable22with the structure inFIG. 34may not be of the same magnitude as the force F generated inFIG. 33.

InFIG. 35, a groove246″″ on a capstan part98″″ has a meandering, curved configuration with peaks248″″ defined at irregular circumferential internals, and different axial positions on the cable-engaging capstan part98″″. This results in the generation of forces F on the cable22at spaced circumferential locations with different magnitudes.

InFIG. 36, a groove2465x′on a capstan part985x′is shown with a bent portion378defined by two generally straight portions at380,382, angled with respect to the direction of travel, as indicated by the double-headed arrow384. The straight portions380,382meet at a circumferential location at386at which the cable22, operatively engaged in the groove246, must abruptly change directions. At the juncture of the sections380,382, a sharpened peak248″″ is defined at which an axial force F is applied to the cable22.

The invention is not limited to a cable22that is wrapped less than 360° around a cable-engaging capstan part. As shown inFIG. 37, a capstan986x′has a groove2466x′extending in a spiral path with axially overlapping circumferential path portions388,390. One or both of the circumferential portions388,390has one or more curved portions3686x′to perform the function of the curved portions368′,368″, previously described with respect toFIGS. 33 and 34, respectively.

The above groove configurations are intended only to be exemplary in nature. Any structure that causes a circumferentially localized force to be generated between a cable and cable-engaging capstan part is contemplated by the invention.

While the construction of the planetary gear assembly244may be designed in many different ways by those skilled in this art, in one form, the planetary gear assembly244is made as outlined in NASA Tech Brief GSC-14207.