Pipe coupling

A pipe coupling for joining abutting sections of pipe particularly adapted for connecting corrugated plastic drain pipe to provide a strong yet flexible coupling having a relatively smooth external surface thereby avoiding entanglement of the coupling in the guide of a trencher for the subterranean laying of the pipe. The pipe coupling consists of a substantially flexible rectangular shaped sleeve having at least two rows of teeth disposed along the length of the sleeve and means for fastening the ends of the sleeve around two sections of pipe to allow each row of teeth to engage at least one corrugated groove disposed at or near the end of each section of pipe to provide a coupling having a wide range of applicability for connecting a variety of corrugated pipe configurations.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a pipe coupling which can be manufactured 
and shipped in a substantially flat configuration and which provides a 
flexible coupling joint achieved by employing a flexible sleeve member, 
flexible teeth or a combination thereof to provide a flexible yet strong 
connection for corrugated drain pipe that is twisted and bent during 
ground laying operations. More particularly, the invention pertains to a 
flexible pipe coupling having a substantially rectangular shaped flexible 
sleeve member having disposed thereon at least two rows of teeth along the 
length of the sleeve for engaging at least one corrugated groove of each 
section of abutting pipe to accommodate a wide variety of corrugated pipe 
configurations. 
2. Description of the Prior Art 
A variety of couplings exist for joining various types of corrugated pipe. 
One form of circularly and spirally corrugated pipe is the rigid metal 
conduit type pipes which employ a variety of virtually rigid couplings for 
joining sections of pipe. Representative of this type of coupling are U.S. 
Pat. Nos. 3,239,254 (FIG. 5); 3,501,179 (FIG. 7); 3,708,187 and 4,061,368. 
Corrugated metal pipes and pipe couplings for metal pipes and markedly 
different from corrugated plastic drain pipes and couplings therefor. In 
metal conduit pipes the trenching and pipe laying operations are not 
carried out in a single operation in that metal pipe couplings do not 
simultaneously require the inconsistent requirements of flexibility and 
strength required of couplings employed for corrugated plastic drain pipe. 
Couplings for plastic corrugated drain pipe must furthermore not have 
flanges which significantly protrude from the outside circumference of the 
coupling which can become lodged in the trencher, resulting in shearing of 
the plastic pipe, failure of the joint and considerable interruption in 
trenching operations. 
Corrugated plastic drain pipe in contrast to corrugated metal conduit pipe 
is employed for draining swamps and fields and is installed by employing a 
trencher which simultaneously digs a trench, lays the drain pipe line and 
with some trenchers also covers the installed drain pipe. During the 
installation of the plastic corrugated drain pipe the pipe is required to 
make a number of bends and turns while being twisted and under tension as 
it moves from the position above ground on the trencher down through a 
guide down to the trencher shoe and into the trench. Furthermore, as there 
is no set standard the manufacturers of corrugated plastic drain pipe 
utilize their own distinctive lip and groove configuration. 
The lack of uniformity between the size, shape, height and width of the 
groove in corrugated plastic drain pipe in conjunction with the procedure 
for installing such pipes has presented considerable problems in providing 
a coupling for joining sections of drain pipe. One such prior art coupling 
for joining sections of corrugated plastic drain pipe is described in U.S. 
Pat. No. 3,899,198. Another prior art coupling of widespread use in the 
field consists of a split plastic sleeve having an appearance similar to 
the corrugated drain pipe. In use this coupling is spread open and the 
corresponding sections of pipe inserted therein to mate with corresponding 
grooves disposed on the drain pipe. These prior art couplings are 
generally the same diameter or of a slightly larger diameter so that they 
can be tied in place with either a bailing wire or twine. 
Hand tied couplings not only required considerable time in opening the 
couplings but also required a high degree of care. When twine was 
employed, the hand tied knot had to be reasonably tight in the groove of 
the sleeve to secure the lip and groove of the underlying drain pipe to 
prevent slippage. On the other hand, use of wire to fasten the coupling 
assured a reasonably tightly secured coupling but resulted in coupling 
failures caused by the tie wire becoming caught in the guide or shoe of 
the trencher. In addition, hand tied wire stressed the tying wire so that 
the stretching involved with the installation and covering of the pipe 
caused the wire to break and the coupling to fail. 
It is critically important in drain pipe joining operations that the sleeve 
or coupling utilized for joining the pipe sections does not allow the 
sections to become disconnected during trenching, pipe laying and covering 
operations. Coupling failure at the least interrupts valuable trenching 
time and requires stopping the trencher, digging up the pipe and then 
recoupling the sections. Alternatively, failure to immediately ascertain 
coupling failure results in improper field drainage requiring ascertaining 
the point of failure, removing crops or structure and then digging up the 
line to repair the coupling. 
The prior art couplings for joining corrugated plastic drain pipe not only 
exhibit the disadvantage of requiring considerable hand labor and time to 
join sections of pipe but also result in increased expense due to the 
inefficiency in packing, shipment and application of prior art circular 
couplings. The problems resulting from the conditions required for plastic 
drain pipe couplings and the difficulties resulting when such couplings do 
not maintain their integrity in trenching operations reveal many of the 
problems involved with prior art couplings. 
SUMMARY OF THE INVENTION 
The disadvantages and limitations of prior art pipe couplings including 
much of the hand labor required for installing and securing couplings to 
plastic corrugated drain pipes are obviated by the present invention. The 
coupling of the invention for connecting abutting sections of corrugated 
plastic pipe includes a substantially flexible rectangular shaped sleeve 
having at least two or more rows of teeth disposed along the length of the 
sleeve and means for fastening and adjustably securing the ends of the 
sleeve around two sections of corrugated pipe to allow each row of teeth 
to engage at least one corrugated groove disposed at or near the end of 
each section of pipe. The novel coupling in part achieves its advantages 
by providing a strong but at the same time flexible connetion for two 
sections of corrugated plastic tubing. The properties of strength and 
resiliency in the preferred embodiment are attained by molding the novel 
coupling of a resilient plastic material such as polyethylene or nylon so 
that the rectangular shaped sleeve in combination with the resilient 
sleeve accomodates the bending, twisting and tension of the corrugated 
plastic drain pipe while the teeth similarly accommodate the expansion and 
contraction of grooves contained on the drain pipe. It will be recognized 
further that the advantages of the present invention can to a lesser 
degree be achieved by utilizing resilient teeth with a narrow 
non-resilient sleeve or a wide resilient sleeve with non-resilient teeth. 
It will further be recognized that the substantially flexible sleeve may 
be achieved by providing one or more flat sections disposed across the 
width of the sleeve to define the teeth and provide flexibility to the 
sleeve. 
The advantages of the invention are attained wherein at least one row of 
teeth or ribs are disposed adjacent to one another along the length of the 
sleeve of the coupling and are adapted to engage at least one transverse 
groove disposed at or near the end of each section of the pipe to be 
joined. Furthermore, any number of rows of parallel teeth or ribs may be 
utilized in the coupling to engage more than one of the grooves in each of 
the sections of the drain pipe to be connected. However, while multiple 
engagement of grooves may provide additional strength to the coupling 
joint, the invention in its preferred embodiment contemplates the 
utilization of a single row of teeth or ribs disposed on either side of 
the pipe joint to accommodate a wide variety of corrugated plastic pipe 
configurations manufactured by the various suppliers of drain pipes. 
Furthermore, it has been found that the necessary strength of the coupling 
is assured by the single row of teeth where a plurality of independently 
locking means is provided for adjusting and securing the ends of the 
sleeve of the coupling tightly around the pipe joint while accommodating 
to a degree the individuality of the lips and grooves defining the 
circumference of different pipes by utilizing the resiliency of the 
sleeve, teeth, and substrate plastic pipe to achieve a secure lock. 
The fastening and adjustably securing means provided at the ends of the 
sleeve of the novel coupling assist in providing the overall resilient 
strength required of a coupling capable of accommodating a variety of pipe 
configurations while flexibly yielding to withstand the bending, torque 
and tension involved in trenching and pipe laying operations. Typically 
the fastening means contemplated by the present invention in combination 
with the rows of teeth are the type that allow a one way tightening of the 
teeth by forcing the teeth into the drain pipe grooves in a secure 
confronting relationship. 
The fastening and adjustably securing means employed may be of the pawl and 
ratchet variety or an adjustable strap employed with interlocking slots or 
a variety of other adjustable mechanical configurations as will be 
discussed hereinafter in greater detail. The fastening and securing means 
may further include a means for first threading and securing one end of 
the coupling to one section of the drain pipe prior to threading and 
securing the adjacent side of the end to the other section of drain pipe 
to be connected. 
The novel coupling allows the sections to be joined by one man quickly and 
efficiently in the field by simply wrapping the flexible coupling around 
the sections of pipe to be connected and engaging the ratchets of the 
fastening means and compressing the ends together causing conforming of 
the sleeve, and teeth to the underlying drain pipe until the teeth are 
forced as tightly into the grooves as the configuration of the drain pipe 
will allow while tightly securing the coupling sleeve around the 
corrugated plastic drain pipe as tightly as the configuration of the drain 
pipe will allow. 
In addition, the configuration of the novel pipe coupling and fastening and 
securing means, allows the coupling to be secured around the pipe in a 
close confronting relationship without portions of the fastening and 
securing means to project or become entangled in the trencher, trencher 
guide or shoe as the pipe is laid in the field. In addition, the present 
coupling is amendable to flat stacking and may be packaged and shipped far 
more efficiently than couplings employed in the prior art. In addition, 
the configuration of the teeth of the coupling in combination with the 
means for fastening and adjustably securing the coupling, provides a 
coupling that is capable of flexibly but strongly holding two sections of 
pipe together so that the pipe can be passed through a trencher guide into 
the trench which during the stretching and bending of the corrugated 
plastic pipe does not result in failure of the coupling securing the two 
sections of the joined pipe. 
Other advantages of the present invention will become apparent to those 
skilled in the art from the specification in conjunction with the appended 
drawings which illustrate various aspects of the novel coupling of the 
present invention.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to FIG. 1, reference character 10 illustrates a trencher 
generally utilized for ground trenching and corrugated plastic pipe 
installation. Trencher 10 employs a conveyor type digging implement 12 for 
digging and removing ground to provide a trench of a predetermined depth 
for the installation of 100 to 250 foot sections of plastic pipe. As 
digging implement 12 removes ground to form a trench, corrugated plastic 
pipe 14 is generally simultaneously installed in the ground through 
trenching guide 16 terminating in a shoe 18 through which the corrugated 
plastic pipe travels for disposition into the trench during the course of 
travel of trencher 10. Guide 16 provides a rather restrictive path of 
travel for pipe 14 since the guide generally has an internal diameter only 
about 1 inch greater than the external diameter of pipe 14. 
Trench pipe 14 may include one or more couplings 20, 22 and 24 for coupling 
sections of drain pipe in the trenching operation. In actual practice 
couplings, 20, 22 and 24 are generally not as close together as depicted 
in FIG. 1 for joining such short lengths of pipe, however couplings 20, 22 
and 24, illustrate the bending, twisting and deformation that such 
couplings undergo as corrugated pipe and coupling travel down guide 16, 
shoe 18 and are covered with ground during the trench and pipe laying 
operations. In particular, coupling 20 in the guide 16 is subjected 
primarily to vertical tension forces expanding the corrugations in the 
plastic pipe while coupling 22 is subjected to torque, binding and tension 
in shoe 18 and coupling 24 is subjected to horizontal tension as a result 
of the movement of the trencher and the covering of the drain pipe as it 
is installed. 
Trencher 10, which is generally in use employs a guide 16 of rather limited 
size which in conjunction with shoe 18 provide a closely confined route of 
travel for the drain pipe 14 and couplings 20, 22 and 24. Generally the 
diameter of the guide 16 and shoe 18 for drain pipe 14 is only slightly 
larger than the diameter of the pipe being installed so that couplings 20, 
22 and 24 must exhibit not only strength and resiliency but also must 
display a compact fastening and adjustable securing means that does not 
have projections which could interfere or become entangled in the bends or 
joints of guide 16 and shoe 18 to result in coupling failure in the 
trencher 10. 
As can be appreciated from FIG. 1, and as will be recognized by those 
skilled in the art the couplings 20, 22 and 24 must provide a reliable, 
strong yet flexible joint to withstand the twisting, bending and tension 
involved in the installation of a flexible corrugated drain pipe. Failure 
of the coupling during trenching operations at any point in guide 16 or 
shoe 18 requires the cessation of trenching operations, the replacement of 
the coupling and the rethreading of the trencher. Failure of the couple 
during the drain pipe covering operation is even a greater problem since 
such failure usually only manifests itself long after the land has been 
planted or otherwise used and requires the contractor to remove crops, 
structures, etc., and uncover at least a portion of the drain pipe to 
replace the coupling. 
Referring now to FIGS. 2 and 3 reference character 30 illustrates a pipe 
coupling constructed in accordance with the invention in its operative 
form, connecting two sections of corrugated plastic pipes. Coupling 30 
employs a flexible sleeve 32 formed of a substantially rectangular sheet 
of semi-rigid plastic or other resilient material. Coupling 30 may be 
formed of such resilient and semi-rigid materials as nylon or other 
thermoplastic material, such as polyethylene, polypropylene or polyvinyl 
chloride and which in the preferred embodiment is manufactured in a 
rectangular shaped flat sheet employing conventional techniques such as 
injection, extrusion or blow molding techniques. Preferably the wall 
thickness of sleeve 32 is about 0.02 to 0.060 although other wall 
thicknesses such as 0.5 inches may be utilized to achieve the advantages 
of the invention. 
Couplings formed utilizing a single molding operation include a generally 
rectangular sleeve 32 having a plurality of flat flexible sections 34 
disposed between ends 36 and 38 of sleeve 32. Sleeve 32 additionally 
includes two rows of bifurcated wedged shaped indentations 40 on the 
outside of coupling sleeve 32 which on the inside of coupling sleeve 32 
forms two parallel rows of corresponding wedge shaped bifurcated 
projections forming teeth 42 for engaging a lip 74 and groove 72 of one 
section of corrugated drain pipe. Teeth 42 formed in the molding operation 
conveniently have a wall thickness generally corresponding to the wall 
thickness of sleeve 32. In the preferred embodiment each resilient 
bifurcated wedge shaped tooth 42 in combination with the sleeve 32 
provides a partially laterally resilient locking combination for plastic 
corrugated drain pipe. 
The resiliency of teeth 42 in combination with a resilient sleeve 32 
provides the necessary flexibility and strength to insure the integrity of 
coupling 30 while the corrugated drain pipe travels down guide 16 (FIG. 1) 
and shoe 18 of the trencher while withstanding the tension, torque, 
bending and other deformation encountered in trenching, laying and 
covering operations. The resiliency of teeth 42 and sleeve 32 assist in 
accommodating the deformation of the drain pipe in trenching and also 
facilitates installation of the pipe by assisting in seating of the pipe 
in the ground, to conforming the drain pipe to the contour of the land and 
promotes pipe life by providing a resilient connection capable of 
accommodating seasonal changes in the ground. If a coupling were to be 
formed of metal or other solid non-resilient material the coupling could 
not be accommodated in present trenching operations for plastic drain pipe 
and, ground corrosion, environments and movements caused by frost heaves 
which would cause non-resilient couplings to crack or tear the corrugated 
plastic pipe and ultimately fail around the joint. 
The necessary combination of strength and flexibility may be achieved 
entirely through either the utilization of a more resilient sleeve member 
32 and non-resilient teeth 42 or the utilization of a less resilient 
sleeve member 32 with a more resilient teeth 42 or a combination thereof 
which is contemplated in the preferred embodiment of the present 
invention. Molding operations and resiliency of sleeve 32 and teeth 42 may 
be fostered by employing circular openings 44 in sleeve 32. These openings 
also assist in allowing ground seepage of water at the joints while 
promoting the flow of excessive volumes of water into the drain pipe when 
the ground around the joint becomes excessively saturated with water. 
The advantages of the present invention are further enhanced and augmented 
by the adjustably securing and fastening means provided in the sleeve 
member 32 to facilitate the joining of ends 36 and 38 of sleeve member 32. 
FIGS. 4, 5 and 6, illustrate the novel coupling in its flat or shipping 
configuration while FIGS. 2 and 3 illustrate coupling 30 in its operative 
configuration connecting abutting sections of drain pipe. In FIG. 4, 
coupling 30 is illustrated with the outside diameter of sleeve 32 facing 
upward whereas in FIG. 5 the inside surface of the coupling 30 is facing 
upward. In FIGS. 2, 3, 4, 5 and 6, one embodiment of an adjustable 
fastening and securing means is illustrated wherein end 36 terminates in 
three V-shaped strap projections 46, 48 and 50. In FIG. 5, an alternative 
embodiment is illustrated wherein one of the straps 46 is longer than 
strap 48 and strap 48 is longer than strap 50 to assist in the joining of 
the coupling around a corrugated drain pipe as will be described 
hereinafter in greater detail. Disposed on the outside surface of each of 
the strap shaped projections 46, 48 and 50 and a series rearward facing 
notches 52. Disposed on end 38 is a corresponding series of openings 54, 
56, and 58 each rearwardly terminating in a series of pawls 60 for 
engaging notches 52 on each of the V-shaped strap projections. In the 
preferred embodiment two such openings are provided in tandem for each of 
the V-shaped strap projection as is shown in FIGS. 3, 4, 5, wherein the 
second opening 62 includes a second pawl 64 for doubly engaging notches 52 
on the strapped shaped projection 46. 
V-shaped strap projections 46, 48 and 50, preferably terminate on the 
underside in a corresponding bifurcated wedge shape (FIG. 5) to provide 
additional lip and groove engagement in the lip 74 and groove 72 of the 
corrugated plastic drain pipe. End 38 contains one or more downwardly 
projecting V-shaped slots 66 and 68 in each of the openings 54, 56 and 58 
to assist in maintaining pawls 60 and 64 in close engagement with notches 
52 provided on each of the strap shaped projections 46, 48 and 50. In the 
preferred embodiment a final V-shaped groove 70 is provided for housing 
each of the strap shaped projections below the outside diameter of 
coupling sleeve 32. 
FIGS. 2, 3, 4, 5 and 6 illustrate a preferred embodiment of the invention 
wherein two rows of teeth 42 are disposed parallel to one another at 
opposite sides of sleeve member 32 to form a coupling for connecting two 
sections of corrugated pipe. In this embodiment the coupling of the 
invention can accommodate a variety of corrugated plastic pipe and pipe 
sizes such as pipe 76 and 78 (FIG. 2) as may be required to be joined at 
the work site. Corrugated pipe 76 may utilize one number of lips 74 and 
grooves 72 per foot while corrugated pipe 78 utilizes a different number 
of lips 80 and grooves 82 of varying depth. Each of the sections of 
corrugated pipes 76 and 78 may also employ their distinctive arcuate slits 
84 to assist in the draining operation of the pipe. The utilization of the 
single rows of parallel teeth of the novel coupling allows the coupling to 
accommodate a variety of types of corrugated plastic pipes. Coupling 30 
engages at least one lip and groove of each of the sections of pipe 76 and 
78 at some point intermediate the end of the respective pipes. Pipes 76 
and 78 are disposed in the coupling in a confronting relationship with a 
space 86 disposed therebetween. As the pipes should be in reasonably close 
proximity but without requiring an absolute seal the novel coupling 
accommodates various pipes within the limits of pipe variation and 
severance of sections by modifying the size of space 86. The size of space 
86 and holes 44 provided in coupling 30 within limits assist in drainage 
and irrigation of the ground surrounding the coupling and allows excessive 
quantities of water to be transported to other sections of the pipe and 
ultimately to a drainage area. Coupling 30 achieves its resilient joint in 
the preferred embodiment by utilizing the resiliency of the sleeve, teeth 
and fastening means to force the resilient teeth 42 in a secure 
confronting relationship to individually accommodate the lips and grooves 
of pipes 76 and 78 to accommodate a wide range of variation in corrugated 
pipes generally found at a work site. 
Referring now to FIGS. 2, 3 and 6, it will be recognized that the means 
provided for joining the ends 36 and 38 of the sleeve 32 provides a 
compact coupling without large projections from the outside diameter of 
coupling 30 to catch in guide 16 and shoe 18 (FIG. 1). The slight 
projections of the pawl project only about 0.125 inches above the outside 
circumference of the coupling. The one way adjustable securement of the 
fastening mechanism allows the coupling to be wrapped around corrugated 
pipe and squeezed around the pipe by hand while the racheting mechanism 
automatically tightens and locks the sleeve around the corrugated pipe to 
the tightest position possible while taking advantage of the resilient 
teeth and the resiliency of the pipe to force teeth 42 into close 
confronting relationship with groove 72 and lip 74 of pipe 76. Teeth 42 
may conveniently be about 0.21 to 0.36 inches wide at the base and about 
0.21 to about 1 inch long at the base and about 0.015 to about 0.20 wide 
at the bifurcated wedge shaped tip and about 0.20 to about 0.99 inches 
long at the bifurcated tip and disposed about 0.5 inches from one another 
along the length of sleeve 32. Preferably teeth 42 are about 0.30 inches 
wide at the base and about 0.5 inches long at the base and about 0.15 
inches wide at the bifurcated wedge shaped tip and about 0.5 inches long 
at the bifurcated wedge shaped tip. 
Referring now to FIGS. 7, 8, 9, 10 and 11 there is illustrated alternative 
methods of adjustably securing and fastening the ends 36 and 38 of sleeve 
32 of coupling 30. FIG. 7 illustrates one method of joining ends 36 and 38 
wherein end 36 terminates in one or more flat shaped straps 100 including 
perforations 102 thereon. End 38 has a correspondingly slot shaped end for 
receiving strap 100 in a groove 104 disposed on end 38, groove 104 having 
a loop 106 provided thereon to assist in the tensioning and fastening 
perforations 102 of strap 100 over corresponding locking projections 108 
provided in groove 104 and a second anchoring loop to secure strap 100 
below the outside circumference of sleeve 32 to prevent accidental opening 
of the locking device while pipes 78, 76 and coupling 30 travel down guide 
16 and base 18 of the trencher. Similarly in FIG. 8 a strap 100 includes a 
plurality of wedge shaped projections 112 for disposition through loop 106 
for mating with corresponding wedge shaped troughs 114 disposed in end 38. 
Referring to FIG. 9, a further embodiment of the means for adjustably 
receiving and fastening ends 36 and 38 of the novel coupling 30 is 
illustrated. In this embodiment a series of cone shaped projections 118 
are provided on a cylindrical rod 120 attached to end 36 of sleeve 32. End 
38 contains a corresponding cone shaped guide and locking mechanism 122 
through which rod 120 and bifurcated cones 118 are threaded and adjustably 
secured against the smaller size cone shaped opening 124 of cone shaped 
guide and locking mechanism 122. 
FIGS. 10 and 11, illustrate a further embodiment of a locking strap 100 
provided on end 36 of sleeve 32. In FIG. 10, strap 100 passes through a 
loop 130 disposed on end 38 with a corresponding loop 132 provided in a 
line with loop 130 through which strap 100 is used to bias against loop 
132 and close ends 38 and 36. Strap 100 contains one or more areas of 
notches 134 which when mated through loop 130 provide an adjustable 
locking mechanism for coupling 30. Similarly in FIG. 11, loop 130 includes 
notches 136 for mating with notches 134 provided on strap 100. 
As will be recognized from FIGS. 4 through 11, and hereinafter in the 
description of the preferred embodiment of the invention, a wide variety 
of locking means for ends 36 and 38 are available and will be apparent to 
those skilled in the art. The invention contemplates such modifications 
and substitutions of various fastening mechanisms without departing from 
the spirit and scope of the invention. It is further contemplated that the 
advantages of the invention will be achieved by utilizing various 
fastening mechanisms that provide a one way adjustable fastening mechanism 
which automatically locks to provide a combination tensioning and 
fastening system to engage sleeve 32 in close proximity to the lips and 
grooves located in the corrugated drain pipe. Couplings for applications 
in trenchers ordinarily employed require that all couplings and 
projections thereon for a 65/8 inch pipe be less than an 1 inch. Couplings 
in accordance with the present invention including fastening and securing 
means increase the pipe diameter by about 0.25 inches. It will be 
recognized that the adjustably securing and fastening system should 
accommodate separate adjustable securement and fastening of each of the 
rows of teeth 42 of the coupling to provide a strong and independent 
engagement and securement of both halves of the coupling around the 
respective pipe sections to best achieve the advantages of the invention 
in utilizing the present coupling for a variety of pipe sizes and 
configurations. 
Referring now to FIG. 12, 13 and 14, there is illustrated the preferred 
embodiment of the coupling 150 of the present invention. Coupling 150 
includes elements such as the substantially flat portions 34, the holes 
44, sleeve 32 and teeth 42, generally which correspond to the coupling in 
FIGS. 4 and 5 and which have been similarly numbered. In coupling 150, 
teeth 42 are rectangularly shaped and have been reduced in size resulting 
in an increase of the width of the substantially flat flexible portions 34 
running the width of the sleeve 32. Coupling 150 further includes 
modifications at end 36 to include two flat strap projections 152 and 154, 
including a plurality of laterally disposed notches 156 thereon. 
Disposed at end 38 for receiving strap 152 are openings 158 and 160, each 
of which opening includes two laterally disposed pawls 162 for engaging 
notches 156. Similarly disposed at end 38 for receiving strap 154 are 
openings 164 and 166 having two laterally disposed pawls 168 for engaging 
notches 156 disposed on strap 154. Coupling 150 further includes a 
plurality of rectangular shaped openings 170 to impart greater resiliency 
to the adjustably securing and fastening means for joining ends 36 and 38 
of the coupling. It will be recognized that the combination of openings 
170, holes 44 and wider sections 34 increase the resiliency of the 
coupling to form a tighter fit around abutting sections of pipe and in 
combination with the teeth 42 provide a coupling suited for the torque, 
twisting, bending and tension encountered in drain pipe installation. 
Referring now to FIG. 15, a further embodiment is depicted of a novel 
coupling constructed in accordance with the present invention. 
In FIG. 15, coupling 180 is amenable to a substantially flat manufacture 
and shipping of the coupling. Coupling 180 includes a substantially 
rectangular shaped sleeve 182 having ends 184 and 186. End 184 terminates 
in a means for adjustably securing and fastening ends 184 and 186 in a 
manner similar to the one depicted in FIG. 9, in which similar parts of 
the adjustably securing and fastening means have been numbered the same. 
The operation of this form of adjustably securing and fastening means for 
coupling 180 similarly functions and operates similar to the description 
of the means for adjustably securing and fastening means described with 
respect to FIG. 9. 
Coupling 180 includes four flat flexible portions 188 disposed along the 
width of sleeve 182 to provide a resilient encircling sleeve 182 for 
coupling corrugated drain pipe. Ends 184 and 186 of sleeve 182 may be 
joined as depicted in FIG. 15 to form a plurality of arcuate shaped ribs 
190 for engaging the lips and grooves of one section of corrugated drain 
pipe. A second series of parallel ribs 192 are provided adjacent to the 
first series of ribs 190 for engaging a corresponding series of lips and 
grooves in a second section of a drainpipe to provide a joint at or near 
the center of coupling 180. Coupling 180 similarly provides a resilient 
sleeve 182 in combination with a series of resilient ribs 190 and 192 to 
provide the advantages of the invention in connecting and installing 
plastic corrugated drainpipe through guide 16 and shoe 18 of the trencher 
10 (FIG. 1) in trenching operations. 
It will be recognized that the present invention has a wide range of 
applicability and is susceptible to modification by those skilled in the 
art to include a greater or lesser number of ribs or teeth to engage 
corrugated drainpipe while providing the advantages of the invention. More 
particularly, the ribs may be subdivided to form smaller wedge shaped 
teeth as heretofore discussed and may be molded in a number of rows to 
engage one or more of the lips and grooves of each section of pipe. The 
preferred embodiment of the invention however contemplates a single row of 
teeth or ribs disposed on each side of the sleeve in order to provide a 
coupling having a wide range of applicability to varying sizes and depths 
of lips and grooves in corrugations encountered in drainpipes in general 
use. 
It is also contemplated that the novel coupling of the invention may be 
modified to include helically corrugated drainpipes by disposing the teeth 
at an angle to the sleeve to accommodate the pitch or angle encountered in 
the helically corrugated drainpipe which disposition of the teeth is 
deemed substantially parallel for the purposes of the invention. In 
addition, the necessary combination of flexibility and strength of the 
coupling may be achieved by providing a resilient bellows type sleeve 
portion. The invention may further be adapted for use with ordinary 
plastic pipes. For example the coupling may be utilized to connect plastic 
pipe having a lip or flange disposed at or near the end of a section of 
pipe to allow the teeth of the coupling to engage the lip or flange 
provided on the pipe to join the abutting pipes in the coupling. 
The advantages of the invention are further enhanced by applying the novel 
coupling to connect sections of pipe wherein one or more couplings are 
joined in tandem and thereafter employed to connect sections of pipe 
having a circumference greater than the length of the sleeve member. More 
particularly the advantages of the invention in this embodiment allows the 
notches on end of the first sleeve member to engage the fastening means 
provided in a second coupling before applying the combined couplings to 
abutting sections of pipe and thereafter joining the notches on the second 
coupling with the means provided on the first coupling. In this manner the 
coupling of the invention may be joined with one another to accommodate a 
wide variety of pipe circumferences in addition to accommodating a wide 
variety of corrugation configurations. 
It will be recognized the invention may be further modified to include the 
application of adhesives or sealants to the coupling to provide a fluid 
tight seal in application where such seals are required. These and other 
modifications and other applications of the present invention may be made 
within the spirit and scope of the invention as defined in the appended 
claims.