U.S. patent number 3,849,999 [Application Number 05/412,213] was granted by the patent office on 1974-11-26 for trailer type mole unit.
Invention is credited to Eugene R. Coffey.
United States Patent |
3,849,999 |
Coffey |
November 26, 1974 |
TRAILER TYPE MOLE UNIT
Abstract
Mole apparatus useful with mobile tractor equipment, such as
mounted rippers, for placing flexible conduit beneath earth
surfaces that are of irregular contour. A flexible towing
connection extends rearwardly from the lower end of a ripper tooth
to engage the lower forward end of the mole structure. The mole has
spaced exterior surfaces, interior plates and guide rollers
providing a protected path through which the conduit moves from an
above-ground point of introduction to a point of discharge beath
the earth surface. Where metal or other rigid pipe is to be placed
or where large pipe is placed with an increased depth of earth
cover, the mole is advantageously pivoted or longitudinally
bendable about lower horizontally transverse axes. Support wheels
maintain the mole in upright position, and power means are provided
for regulating the position of said wheels to govern the placement
depth for the conduit. Power means additionally and selectively
regulate the operative length of said tow connection.
Inventors: |
Coffey; Eugene R. (Montrose,
CO) |
Family
ID: |
23632073 |
Appl.
No.: |
05/412,213 |
Filed: |
November 2, 1973 |
Current U.S.
Class: |
405/178; 172/700;
37/370 |
Current CPC
Class: |
E02F
5/102 (20130101) |
Current International
Class: |
E02F
5/10 (20060101); F16l 001/00 (); A01f 011/00 () |
Field of
Search: |
;61/72.6,72.5,72.7,72.1
;37/193 ;172/700 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Shapiro; Jacob
Attorney, Agent or Firm: Messenger; C. B.
Claims
I claim:
1. Mole apparatus for use with mobile tractor equipment to place
conduit beneath earth surfaces that may be of irregular contour
wherein a tractor mounted ripper tooth with separate depth control
is provided comprising a separate mole implant unit for use behind
the said ripper tooth of operative height whereby a portion of the
mole unit is adjacent or above the earth surface for all selected
penetration depths of said ripper tooth and mole, said mole unit
having front and side plates providing an entrance opening at a
position above the earth surface for introduction of a main conduit
and a guide passage therethrough for directing said conduit along a
path to the bottom of said mole whereby said conduit is deposited
and placed at the bottom of the earth structure disturbed by the
ripper tooth and mole unit, a leading edge on said mole unit
disposed at a rearwardly inclined angle upwardly from the bottom of
said mole, a tow connection for extension between the bottom of
said ripper tooth and the front lower bottom of said mole for the
transmission of towing force from said ripper tooth to said mole
unit, said tow connection being inclusive of means flexibly
interconnecting said ripper tooth and mole unit whereby said mole
is adapted for independent movement and rotation with respect to
horizontal and vertical axis of reference, and stabilization means
interconnected to said mole for engagement with the surface of the
supporting earth for holding said mole in substantially vertically
oriented positions as the ripper tooth and mole are moved over
irregular earth surfaces.
2. The mole apparatus of claim 1 wherein said tow connection is of
length corresponding to at least the penetration depth for said
ripper tooth.
3. The mole apparatus as set forth in claim 1 and further
comprising powered depth control apparatus for regulating the
positioning of said stabilization means.
4. The mole apparatus as set forth in claim 3 and further
comprising wheel mountings for said stabilization means.
5. The mole apparatus as set forth in claim 3 and further
comprising hydraulic cylinders providing the depth control for said
stabilization means.
6. The mole apparatus as set forth in claim 5 and further
comprising separately operable stabilization means on opposite
sides of said mole unit, and separate means for the selective
positioning of said separate stabilization means whereby said
stabilization means is cooperatively positionable to maintain the
mole in vertically oriented position as the ripper tooth and mole
are moved along laterally inclined and sidehill surfaces.
7. The mole apparatus as set forth in claim 1 wherein said tow
connection is itself flexible to accommodate bending movement
intermediate said ripper tooth and mole.
8. The mole apparatus as set forth in claim 7 wherein said tow
connection is provided by a cable.
9. The mole apparatus as set forth in claim 7 and further
comprising means for adjusting the length of said tow
connection.
10. The mole apparatus as set forth in claim 9 wherein said length
adjusting means comprises a cable system and hydraulic powered
apparatus for regulating the effective length of said cable.
11. The mole apparatus as set forth in claim 10 wherein a hydraulic
cylinder is provided for adjusting the length of said tow
connection cable.
12. The mole apparatus as set forth in claim 11 wherein said
hydraulic cylinder is additionally useful to provide depth control
for regulating the positioning of said stabilization means.
13. The mole apparatus as set forth in claim 1 wherein the tow
connection intermediate the ripper tooth and said mole unit is
inclusive of a mole extension component and further comprising
pivot means interconnecting said mole unit and said mole extension
whereby said mole unit and extension are pivotally movable one with
respect to the other in a vertically oriented plane.
14. The mole apparatus as set forth in claim 13 wherein said mole
extension additionally provides a through passage for the reception
and guidance of a main conduit whereby the total arcs of curvature
through said mole unit and extension are lessened for the
accommodation of more rigid conduits.
15. The mole apparatus as set forth in claim 14 wherein the front
plate for said mole unit is selectively removable to increase the
size of the entrance opening for said mole unit when more rigid
conduit is to be placed.
16. The mole apparatus as set forth in claim 14 wherein a plurality
of mole extensions are provided for interconnection intermediate
said mole unit and ripper tooth and further comprising pivot
connections between the separate mole extensions and the mole unit
to accommodate vertical bending of said mole apparatus.
17. The mole apparatus as set forth in claim 1 wherein said mole
front plate is disposed along said leading edge and further
comprising angularly disposed fins on said ripper tooth and
extending outwardly and upwardly from the forward bottom portion
thereof whereby coarse materials disturbed by the ripper tooth are
displaced upwardly and rearwardly as the tooth passes along a
ripped path and wherein the front plate and leading edge of said
mole are disposed rearwardly from said ripper tooth a distance
corresponding to at least the penetration depth for said ripper
tooth whereby materials disturbed by said ripper tooth and fins
will settle in the ripped path before recontact and re-elevation by
said inclined front plate whereby coarse materials are moved away
from positions surrounding the emplaced conduit.
18. The mole apparatus as set forth in claim 1 wherein said mole
unit is additionally useful for the simultaneous placement of main
and auxiliary conduits and further comprising a cutter element
positioned at the front of said mole unit at an elevation above the
bottom of the mole and an auxiliary conduit placement attachment
disposed at the rear of said mole at a level corresponding to the
level for said front cutter element, and an auxiliary guide chute
provided by said mole apparatus whereby an auxiliary conduit is
delivered from an above ground position to said auxiliary conduit
placement attachment.
19. The mole apparatus as set forth in claim 18 wherein said front
cutter element and said auxiliary conduit placement attachment
extend laterally and outwardly from said mole unit to provide a
ripped path of wider extent corresponding with the positioning of
said elements.
20. The mole apparatus as set forth in claim 19 wherein said front
cutter element and rear auxiliary conduit placement element are
removably attached to said mole unit for extension outwardly and
laterally from each of the sides thereof.
21. The mole apparatus as set forth in claim 20 and further
comprising rearwardly and upwardly extending surfaces for said
front cutter element and rear auxiliary conduit placement element
whereby materials in the path ripped by said elements are initially
displaced upwardly and rearwardly by the inclined surfaces of said
front cutter element and are subsequently recontacted and
re-elevated by the inclined surfaces of said auxiliary conduit
placement element whereby coarse materials are moved away from
positions surrounding the emplaced auxiliary conduit.
Description
BACKGROUND OF THE INVENTION
In previous patents issued to the present inventor, mole units are
provided that facilitate the emplacement of various types of
flexible conduit. The earlier mole attachments disclosed in the
previous U.S. Pat. Nos. 3,344,615 and 3,429,134 are preferably used
with trail mounted ripper apparatus. More than a thousand miles of
pipe have by now been placed utilizing the previous types of
equipment. Prior beneficial operations include the placement of
six-inch plastic pipe at depths providing a seven-foot earth cover.
In the accomplishment of such earlier installations, the novel mole
movements pattern resulting from the use of a low pivot attachment
between the ripper tooth and mole and the trailing characteristics
for trail mounted type rippers have prevented breakage of the pipe
being placed. The number of leaks experienced when the lines are
initially tested or after subsequent and continued usage has been
quite low. The same beneficial results have not been obtainable by
others when mole units are used with the more extensively available
tractor mounted rippers. The abrupt changes in ripper tooth depth
when the mounting tractor encounters changes terrain conditions
apparently causes excessive stressing and breakage of the conduit
being placed.
SUMMARY OF THE INVENTION
In order to improve the efficiencies of underground pipe placement
where mounted rippers are to be used and, further, to provide an
increased capability so that the more rigid types of metal pipe or
pipe of larger size can be placed at increased depth, the present
invention provides a mole unit that can be joined to the ripper
tooth of mounted ripper equipment to follow therebehind in a
trailer type arrangement. The trailer mole is joined to the bottom
of the ripper tooth by a flexible tow connector engaged to the
lower front end of the mole. Support wheels are provided to
maintain the mole in a vertically oriented position and to adjust
the earth penetration depth of the mole. The flexible tow
connection courses along the bottom of the earth structure cut and
disturbed by the ripper tooth, and the mole itself is drawn by the
tow connection along the previously cut path. Inclined spoon bill
type surfaces on the mole keep the unit at the bottom of the ripped
path. The mole is isolated by the flexible connection from any
erratic or violent up and down movements of the mounted ripper as
the tractor courses along a supporting earth surface that may be of
irregular contour and along paths where boulders or similar sharp
raises or declivities may be encountered. In further embodiments of
the invention the effective length of the flexible tow connection
may be selectively changed through use of power apparatus that
adjusts the trailing distance for the mole. Where metal pipe is to
be installed or where larger sizes of conduit are to be placed,
mole extension components provide features permitting longitudinal
bending of the mole about lower transverse axes.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation in partial section showing operative
features of the invention,
FIG. 2 is a side elevation illustrating one mole embodiment,
FIG. 3 is a top plan view of the mole unit shown in FIG. 2,
FIG. 4 is a partial enlarged top view showing an auxiliary conduit
placing attachment,
FIG. 5 is a side view of the attachment shown in FIG. 4,
FIG. 6 is a side elevation in partial section showing additional
features of the mole embodiment,
FIG. 7 is a top view of enlarged size showing a lateral ledge
ripper applied to the mole,
FIG. 8 is a side elevation further illustrating the ledge ripper of
FIG. 7,
FIG. 9 is a cross-sectional elevation providing a conduit
emplacement representation,
FIG. 10 is a side elevation showing a mole embodiment of extended
length providing vertical flexibility,
FIG. 11 is a diagrammatic side view showing use of such extended
mole coursing along a raised earth structure,
FIG. 12 is a diagrammatic side view showing use of such extended
mole coursing along a depressed earth structure,
FIG. 13 is a side cross-sectional elevation showing a further
embodiment of the invention, and
FIG. 14 is a side cross-sectional elevation showing an additional
modified embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Features of a first embodiment of the invention are shown in FIGS.
1 through 9. Such embodiment provides a mole attachment or mole
unit 12 that is adapted to be trailed behind a track-laying tractor
13 which carries a mounted ripper system 14. A flexible tow
connection, such as a chain or the cable 16, interconnects the
forward end 17 of the mole 12 and the bottom 18 of a ripper tooth
19. The tow connection 16 is preferably flexible so that it may
bend as it is drawn through disturbed earth structures 21 that have
already been ripped by the ripper tooth 19, its lower ripper point
22 and/or by the depth control fins 23 disposed angularly at the
bottom of the ripper tooth. Since the mounting tractor 13 itself
may be connected to other towing tractors by a cable 24 or by
various types of tandem interconnections now used for joining a
plurality of track-laying tractors together, a substantial draw bar
pull is exerted on the ripper mount 14 for transmission to the
ripper tooth 19. Undisturbed earth structures 26 that may include
rocks, boulders, shales or even sandstones can be ripped by such
arrangement to provide a loosened earth structure 21 behind the
ripper tooth 19. The mole unit 12 is drawn along such predisturbed
path by the flexible connection 16. The inclined flat surface 27 on
the mole 12 and impingements thereof against the ripped earth
structure causes the lower bottom 28 of the mole to stay in contact
with the surface defined by the prior passage of the ripper tooth
19. The mole 12 is itself of near hollow construction, and,
accordingly, flexible conduits, such as the pipe 29, may be
introduced into the interior of the mole for passage therethrough
to a point of discharge at the rear lower end 31 of the mole 12.
The depth of penetration for the ripper tooth 19 is controlled by
the positioning of the connector pins 32 of the ripper mount and
mating holes or receptacles 33 disposed in vertically spaced
positions along the length of the tooth 19. The penetration depth
for the ripper tooth is also controllable through actuation of the
mount cylinders 34 which can be used to lower the ripper tooth to a
full penetration depth or alternately to raise the tooth to a
position where the forward point 22 is out of contact with the
supporting earth.
The described tow arrangement is highly beneficial when compared to
other systems for mounting and towing a mole implant attachment
when used with mounted type rippers. Where mole attachments are
directly attached to a mounted ripper by pivot means disposed at
variously spaced vertical positions at the rear of the ripper,
moles of substantial length will be subjected to rather abrupt
vertical movements as the tracks of the mounting tractor 13 move
over raised obstructions or across short declivities. The use of a
single pivot disposed at the lower end of the mole and the ripper
tooth in keeping with the teachings of the mentioned prior art
patents minimizes the difficulties experienced but does not fully
eliminate the problem especially where larger sizes of plastic
tubing or pipe are being placed or where other less flexible
conduits are to be buried at intermediate and excess depths. The
mole attachments to be used with larger sized pipe or more rigid
conduit structures are necessarily longer to accommodate even the
medium radius bends to which the pipe may be subjected. With long
mole units the rear exit end will be subjected to increase
displacements and abrupt movement patterns when the mole is
connected to a tractor mounted ripper. The mole attachment 12 shown
herein is moved through preripped earth structures by the flexible
tow connection 16, and the mole tends to stay in contact with the
bottom of the ripped path. Up and down movements of the forward end
17 are avoided, and similarly the rear or exit end 31 is not
subjected to abrupt movement patterns. Accordingly, the pipe or
conduit 29 being placed will uniformly be discharged at or near the
bottom of the ripped pathway.
Since only the flexible connection 16 provides towing or guidance
forces for the mole, it is necessary to provide auxiliary
stabilization for the mole. A wheel mount system is provided to
hold the mole at all times in near upright position and to
selectively elevate or lower the mole with respect to a ground
surface. Features of a wheel mount system 30 are shown in FIGS. 1
and 2. A support frame 36 is provided at the top of the mole 12.
The support frame is divided centrally to provide an upwardly open
entrance channel 37 into which the pipe 29 being placed is
introduced. Separate hydraulic cylinders 38 are disposed on
opposite sides of the frame 36 for interconnection to crank arms 39
for the wheel mount apparatus 30. The crank arms 39 are joined to
torque tubes 41 which fit over laterally extending pivot axles 42.
Action arms 43 are joined to the torque tubes 41 for movement
therewith. Accordingly, as the shafts 44 of the hydraulic cylinders
38 are extended, the crank arms 39 will be rotated to move the
action arms 43 to adjusted positions. Support wheels 46 are
disposed on the stub axles 47, which are mounted on the free ends
of the action arms 43. As the wheels are lowered with respect to
the mounting frame 36, the entire mole 12 will be elevated. The
mole can be brought to a full above-ground position as shown in
FIG. 2, and towing eye 48 at the forward end 17 of the mole 12 can
be coupled to a towing tractor or truck to be moved to any required
alternate work sites. Desirably, the mole 12 will be substantially
balanced fore and aft and side to side when the wheels are in the
lowered configuration shown in FIG. 2. When properly balanced, mole
units of substantial weight can be moved along roads and highways
by relatively small trucks or tractors. When the mole is to be
moved to other work sites, hydraulic supply hoses 49 can be
separated at a quick disconnect connector 51 that may be mounted on
the towing tractor 13 or on the mole frame 36 as illustrated. These
hydraulic supply lines 49 are at time of use for the mole 12
interconnected to a control valve 52 adjacent the operator's
position on the tractor. With this arrangement the operator can
adjust the position for the supporting wheels 46 when the mole is
being introduced into the ground or removed therefrom or to make
depth adjustments during the pipe laying process. The provision of
separate hydraulic cylinders and crank arms for rotation on a
non-moving pivot axle 42 makes it possible to provide individual
control for the separate action arms 43 and wheels 46 if pipe is to
be laid along a side slope.
A cross-sectional representation of the mole attachment 12
described is shown in FIG. 6. In this drawing it it seen that an
internal frame work of metal diaphragm segments 53 interconnects
the exterior sidewalls 54. Preferably the angled diaphragm segment
53 should extend from the front rearwardly inclined plate 56 to the
rear discharge opening 57. Such rear discharge opening is in part
defined by the lower edge 58 of the sidewalls 54 and by the rear
truncated edge 59 of side plates 54. A guide passage for the pipe
being placed extends from entrance opening 37 and is defined as it
passes rearwardly through the mole attachment by the diaphragm
plate 53 and by segmental plates 61 which, together with permanent
guide rollers 62, 63 and 64, serve to prevent abrasion of the pipe
being implanted. At the rear a pivot mounted guide roller 66 is
biased toward contact with the pipe being placed by a spring 67. A
partial front plate 68 is removably positioned at the forward end
of the attachment 12 to be selectively held in such position by a
fastener plate 69. The plate 68 can be removed to provide a larger
entrance opening when less bendable types of pipe, such as pipe
made of more rigid materials or pipes of larger flow diameter or of
thicker wall sections are used.
In addition to the main passage provided through the mole unit 12
to facilitate placement of a main conduit, FIG. 6 shows the
provision of an auxiliary guide chute 71 that may be used in
connection with the simultaneous placement of auxiliary conduits or
cables. FIGS. 1 through 9 illustrate features of such auxiliary
conduit emplacement apparatus. At many work sites where mole
implant apparatus is to be used, there is often more than one
conduit system to be installed. Water lines, natural gas supply
lines, electrical power cables and telephone services are often all
required when housing installations are being made. At all
installations at least one large size conduit is usually required.
Other household type supplies may be of lesser size. If water lines
are installed, they usually will be of the largest size, and the
required depth of placement is usually greatest for water lines to
prevent freezing or breakage of the lines due to soil stresses or
surface loadings. Many communities now permit the installation of a
plurality of services along a single right-of-way. Where trench
digging procedures are used, it is usually required that separate
utilities be disposed at different elevations or even in laterally
spaced positions. Gas and electrical conduits can often be placed
in a single ditch excavation together with a water line if the
ditching procedure can provide a separate bench support for the
auxiliary utilities so all of the lines will be adequately
supported by undisturbed earth structure. At some locations
supporting benches must be provided at laterally spaced positions
and at separate line elevations. Operations with the present
apparatus indicate that multiple utility installations can be made
through use of the large scale ripper equipment disclosed herein.
Mole apparatus of the type described has been used to place plastic
water lines in northern climates at depths providing a seven-foot
cover in order to prevent freezing of such lines. If a large
conduit, such as a water pipe, is to be placed at depths of 4 to 7
feet, little additional power or work is required to simultaneously
install auxiliary conduits. FIG. 9 illustrates the type of
installation that can be made and that will fully satisfy the
requirements of design engineers concerned with utility
placement.
In FIG. 9 the previously disturbed earth structure 26 has been cut
by the passage of a ripper tooth 19 and mole through the zone 76. A
pipe conduit 72 has been placed at the bottom of the ripped
section. If wing attachments are provided to extend outwardly from
the side plates 54 of the mole attachment 12, the disturbed zone
can be laterally extended, as shown at 73 and 74, to provide
support benches 75 and 77 adapted to receive and support auxiliary
conduits 78 and 79. Main conduit 72 and the auxiliary conduits 78
and 79 could represent a water main 72, a gas line 78 and an
electric power conduit 79. The same illustration could also be
representative of an installation for a main co-axial cable with
auxiliary ground cables therefor or of other utility
installations.
If auxiliary cables are to be placed along the same ripped pathway,
support bench cutting elements will be applied to the mole 12. A
lateral cutter element 81 is attached to the front of the mole 12,
and an auxiliary conduit placement element 91 is attached to the
rear of the mole at an elevation corresponding to the elevation for
the lateral cutter 81 and at a position communicating with the
auxiliary conduit chute 71.
Construction features for the lateral cutter element 81 are shown
in enlarged detail in FIGS. 7 and 8. In these FIGS. the cutter
element 81 is shown at a position extending across the inclined
surface 27 at front plate 56 and laterally outward from the mole
side plates 54. A plow type point 82 is provided at the
intersection of angularly disposed segment 83 and a rearwardly and
upwardly extending wing surface 84. The internal surfaces of
segment 83 and of wing surface 84 closely engage support blocks 86
fastened in permanent position on the mole side plates 54. With
this arrangement the cutter element 81 can be placed on the blocks
86, and it will be held by a wedging action in its desired position
by the continued impingement of such attachment against ripper
disturbed earth. When auxiliary cables are not being placed, hammer
blows directed against the rear edge 87 of cutter 81 will be
effective to remove the attachment.
Features of the rearwardly disposed auxiliary conduit placement
elements 91 are best shown in enlarged detail in FIGS. 4 and 5.
This auxiliary attachment is selectively positioned on the mole 12
by use of a single through-bolt 92. This bolt extends through
paired side plates 93 which are of a size to engage the outside
surface of mole side plates 54. Auxiliary conduit placement
attachment 91 is essentially a hollow box like structure providing
an internal passage that widens vertically to a dimension
corresponding with the outside dimension for the auxiliary guide
chute 71. When in the proper position, the attachment 91 will
surround the exit opening 94 of such guide chute 71. Accordingly,
any auxiliary conduits introduced through the guide chute 71 will
be discharged into the interior of the attachment 91. Paired exit
outlets 98 and 99 are separately provided to guide and position the
auxiliary conduits 78 and 79 to positions on their respective
support benches 75 and 77. Such support benches are, of course,
precut by the side flaring wing portions 84 of the front attachment
81 and are reopened by the rearwardly and upwardly inclined ramp
surfaces 95 and 97 provided by the attachment 91 at positions
coordinated with the positioning for conduit outlets 98 and 99. A
central divider 101 is provided within the attachment 91 to guide
the auxiliary conduits into their respective divergent
positions.
FIGS. 10 through 12 illustrate mole extension apparatus that can be
used together with the mole 12 where the more rigid types of pipe
or conduit are to be installed. Natural gas, petroleum and water
lines are often extended across great distances. When lines are
subjected to higher flow pressures or increased soil stress, metal
pipe is frequently used. Metal pipe, as well as some types of
plastic pipe of larger diameter, is relatively rigid and the
maximum bend arcs permissible would prevent placement through use
of a mole attachment that was itself of somewhat rigid
construction. In order to accommodate such rigid pipe and pipe of
larger diameter and to still provide an implant system that can be
used for pipe installation along ground structures of irregular
contour, mole extension components are provided for cooperative use
with the basic mole attachment 12 heretofore described. A forward
extension 102 having a towing eye 108 is positioned forwardly of
the mole 12 and interconnected to an intermediate extension 112.
The forward extension 102 has side plates 104 that extend past and
over the side plates 114 for the intermediate extension 112. A
pivot 103 interconnects the extensions to provide relative pivoting
movement of the forward extension 102 with respect to the
intermediate extension 112 in a vertically oriented plane. A
further pivot type connection 113 is disposed adjacent the bottom
of mole extension 112 for connection to the towing eye 48 of mole
12. As in the prior instance, the side plates 114 of the
intermediate extension 112 cover and slide reciprocally over and
along the side plates 54 for the mole 12. When the mole extensions
102 or 112 are joined to the mole attachment unit 12, the forward
partial front plate 68 as shown in FIG. 6 will be removed so that
the entrance opening is expanded. With this arrangement a pipe or
other conduit 29 may be strung through the combined mole unit along
a line as indicated in FIG. 10. The support axles and wheels 46,
etc. can still be used when the combined mole is to be raised.
Actually the wheel mount system will in such circumstances raise
the rear mole 12 and the forward towing eye 108 can be directly
connected to the ripper tooth 19 to raise the forward end of the
combined unit. Movement limiting stops 106 and 107 can be provided
on the extensions and mole 12 to limit the telescoping or sliding
movement of the outermost side plates with respect to the plates of
the following mole or extension unit.
With the arrangement described the combined and extended mole may
still be beneficially used to make installations of rigid types of
pipe or conduit along earth structures of irregular contour.
Installation over humped terrain is shown in FIG. 11, while
installation across a depression or ravine is shown in FIG. 12. For
all such usage the provision of a connector, such as towing eye
108, at the lower end of the combined mole assembly will tend to
keep the bottom of the mole units in position along the bottom of
the earth ripped or disturbed by the ripper tooth. The vertically
oriented flexibility will further prevent abrupt movements of the
discharge end 31 for the mole attachment 12, and, accordingly,
severe abrasion or breakage of the pipe will be avoided. The pipe
will also at all times be placed with a depth of cover sufficient
to comply with engineering and installation requirements.
FIG. 13 illustrates a further embodiment of the invention providing
a tow connection or cable 116 that can be of selectively adjustable
length. A hydraulic cylinder 118 is shown disposed within the mole
122. The cylinder is connected by hydraulic lines 119 to a quick
disconnect supply 51. Actuation of the hydraulic system will then
power extension and/or retraction of the cylinder shaft 121 to move
a crosshead pulley 123 to extend or retract the flexible tow cable
116. One end of cable 116 is anchored to the mole 122 or to the
hydraulic cylinder 118 by an anchor 124. A hydraulic accumulator
126 can be provided in the system for the purpose of absorbing
shock loadings that might otherwise tend to damage the tow cable or
the mole attachment or other associated equipment. Use of this
hydraulic system can, of course, control the effective length of
the towing cable 116 in order to shorten or extend the working
distance between the mole 122 and the ripper tooth 19. This powered
extension feature will have many advantageous uses during actual
implant operations. The cable can be extended or shortened to
provide increased tractive power as required, since the tractor can
be moved past obstructions or areas of loose soil that would impair
or lessen the draw bar pulling capability for the tractor 13 or the
other tractors that may be interconnected thereto by the forward
cable 24. Similarly, the cable 116 can be extended or retracted to
provide clearance for the use of auxiliary digging equipment that
is often used to remove large boulders or other underground
obstructions from the implant pathway to avoid damage to the
relatively thin side plates of the mole unit. Without such
extension features the towing tractors sometimes need to be
disconnected from the mole or the mole itself has to be raised out
of the earth so that obstructions can be cleared. Job site
conditions can often require disruption or discontinuance of the
mole implant operations where difficult soil conditions are
encountered if the mole itself is moved without a corresponding
continuance of the pipe implanting functions. Where a flexible tow
connection, such as even the cable 16, is used the tractor units
can be backed up and moved without causing a corresponding movement
backward of the following mole. If the towing cable itself can be
extended and retracted as shown in FIG. 13, an increased freedom
for independent movement of the tractor and mole is possible. With
the system shown in FIG. 13 operations need not be discontinued
even though extremely poor soil conditions are encountered. The
tractive equipment can with such system be parked to provide a
deadman anchor, and the mole can be moved along its intended course
by successive extensions and retractions of the tow cable 116.
A further development providing a tow cable of adjustable length is
illustrated in FIG. 14. In this embodiment of the invention the
cable 136 extends through a forward opening 134 in the mole 132 and
thereafter courses over a pulley 133 disposed within the mole 132.
The cable 136 is by a succession of pulleys and guideways
interconnected to the normally anchored end 139 of a hydraulic
cylinder 138 that is interconnected to the support wheel crank arms
39. The cylinder 138 is normally used for moving the support wheels
46 as previously described. Once the wheels are moved to a full
elevated position and the mole is at a full penetration depth in
the earth, the wheels 46 and the crank arms 39 may be locked in
place. A pin at the normally anchored end 139 of the hydraulic
cylinder 138 can then be removed to free such anchored end.
Actuation of the hydraulic cylinders will then cause extension of
the cylinder housing itself, and the cable 136 attached to such
housing will, accordingly, be retracted thereby providing the
desired effective shortening of the tow connection 136. With this
arrangement the hydraulic cylinders and the associated control
equipment have multiple usage, and the hydraulic cylinders are kept
at an elevated and above-ground position.
Where an adjustable tow connection is provided, the operative csble
length can be changed to meet the requirements of various job site
locations. Where flat level ground is to be crossed, the cable
could be shortened to an operative length less than the penetration
depth for the ripper tooth itself. Usually a best operating length
that will avoid abrupt movements of the mole would be in excess of
a distance corresponding to the penetration depth for the ripper
tooth. Longer effective lengths for the tow connection will usually
be used where raises and declivities are to be encountered. Where
flexible tow connections or cables of fixed length are to be used,
such connections should usually be at least as long as the expected
maximum penetration depth for the ripper tooth. Where the tow
connection is longer than the penetration depth, the ripper tooth
can be raised out of the earth without disturbing or moving the
mole unit. When raised to such position, the ripper can be
disconnected for independent use, such as preripping operations or
to facilitate the clearing of obstructions. Subsequently, the
ripper can be reconnected and conduit implant operations can be
resumed.
In addition to providing an arrangement where the towing tractors
can be connected or interconnected to the mole implant unit at will
and without disturbing the conduit placing functions of the mole
unit, the present disclosure provides an overall system that will
give an improved conduit placing result. Where a flexible tow
connection is used, violent or abrupt movements of the mole are
avoided, and the pipe is not subjected to the lateral or vertical
forces that will cause immediate breakage or that will subject the
pipe to stresses that will result in subsequent leakage or
problems. The ripper tooth for a mounted ripper system is often
moved abruptly through erratic patterns as the tractor moves over
and across irregular terrain. Though such undesirable movement
patterns can, in part, be corrected by operator manipulations of
the tooth mounting apparatus, such effects cannot be eliminated and
the pipe being implanted by a mole that is closely attached to the
ripper tooth can be broken or damaged.
The flexible tow connection also works beneficially with other
features of the described apparatus to provide an improved bed of
earth to receive and surround the placed pipe. The fins 23 on the
sides of the ripper tooth help to hold the tooth downwardly in the
ground, and they also operate to elevate rock and coarse materials
upwardly and away from the ripper point 22 and lower end of the
ripper tooth. While rock and larger pieces are elevated by the fins
23, dirt and other materials of small size fall downwardly into the
bottom of the ripped path. The forward surface 27 for the mole unit
12 again clears the ripped path, and the bottom 28 of the mole, as
shown in FIG. 1, generally stays at a slight elevation above the
lowermost area disturbed by the ripper tooth point 22. With this
arrangement the pipe being placed is deposited on a bed of
essentially fine materials that have been slightly prepacked by the
bottom 28 of the mole and that will, accordingly, provide good
support for the pipe in place. The materials that subsequently fall
to surround the pipe are likewise of finer particle size;
accordingly, the pipe will not be damaged by the impact of falling
materials. A pipe that is surrounded by finer materials will not be
as subject to damage by reason of subsequent soil stresses that are
concentrated and applied at a point rather than being distributed
along the pipe. Any sharp rocks or other materials that might
provide a fulcrum at the bottom of the ditch that would be in
contact with the pipe are covered by the loose materials in the
bottom of the ripped path, or they are substantially levelled by
passage of the bottom of the mole itself.
In order to minimize the occurrence of "fulcrum" breaks when pipe
is being placed in soils or shales having sharp edged rocks, it has
previously been found desirable to interconnect the mounted ripper
tooth and the mole unit so that the mole unit will trail the ripper
tooth at a position two or more inches above the lower extent of
the ripped path. With the present apparatus a most beneficial
placement depth can be derived by adjusting the aboveground
positioning of the support wheels 46 and also by changing the point
of lower attachment for the tow connection 16 at the bottom of the
ripper tooth 19.
The same bedding advantages are also provided in connection with
the placement of the auxiliary conduits. The rearwardly and
upwardly extending wings 84 of the lateral cutter element 81
disposed at the front of the mole similarly serves to elevate
coarse materials so that the auxiliary conduits will be bedded in
loose materials on their respective support benches. The action of
the front wings 84 and the rear inclined ramp surfaces 95-97
provide a dual displacement feature corresponding to that of the
control fins 23 and the front inclined surface 17 of the mole 12.
Where the coarse materials are disturbed and elevated and then
subsequently elevated again, finer bedding material characteristics
are noted. This beneficial result could be derived from the soil
contacting two disturbing surfaces one after the other and thus
tending to break up coarse materials in addition to the dual
elevating aspects of the present equipment. With this trailer type
of mole it has in general been noted that the ripped path itself is
substantially similar to that derived when a pipe implant course is
initally preripped before the subsequent passage of a ripper tooth
and close coupled mole unit.
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