US3686888A

US3686888A - Pipe laying apparatus

Info

Publication number: US3686888A
Application number: US12717A
Authority: US
Inventors: Marion P Helton
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-02-19
Filing date: 1970-02-19
Publication date: 1972-08-29
Anticipated expiration: 1989-08-29

Abstract

For laying a string of pipe, a main sled and the trailer sled are adapted to be towed in a trench by a trenching machine. The sleds slide along the trench bottom on parallel runners and define a generally continuous pipe supporting surface inclined downwardly from the leading end toward the trailing end. The sled supports the end of the assembled pipe string, the next pipe section to be joined to the string for facilitating the assembly. The sleds are self centering within the trench and carry implements for preparing the trench bottom to receive the pipe string.

Description

United States Patent Helton 1451 Aug. 29, 1972 [54] PIPE LAYING APPARATUS [72] Inventor: Marion P. Helton, P. O. Box 162,

Plummerville, Ark. 72127 22 Filed: Feb. 19, 1970 21 Appl.No.: 12,717

52 US. Cl. ...61/72.1, 193/35, 193/41 51 1111. C1. ..F16l 1/00, 365g 15/08 [58] Field 61 Search ..61/72.1, 72.5, 72.6, 72.7, 61/723, 63, 41, 43; 193/35, 38,41, 42

[56] References Cited UNITED STATES PATENTS 3,421,609 1/1969 Schmunk ..61/72.5 x 2,979,178 4/1961 Harnre... ..193/41 x 2,704,143 3/1955 Cushman ..193/35 2,790,887 4/1957 Gelfand ..49/246 x 10/1921 Chapman ..61/72.3 9/1970 Blinne ..6l/72.6R

Primary Examiner-Jacob Shapiro Attomey-Giles C. Clegg, Jr. and Peter J. Murphy [57] ABSTRACT For laying a string of pipe, a main sled and the trailer sled are adapted to be towed in a trench by a trenching machine. The sleds slide along the trench bottom on parallel runners and define a generally continuous pipe supporting surface inclined downwardly from the leading end toward the trailing end. The sled supports the end of the assembled pipe string, the next pipe section to be joined to the string for facilitating the assembly. The sleds are self centering within the trench and carry implements for preparing the trench bottom to receive the pipe string.

13 Claims, 9 Drawing Figures PATENTEDM B 3.886.888

sum 2 or 2 MARION P HELTON ATTORNL BACKGROUND OF THE INVENTION This invention relates to apparatus for use in assembling a string of pipe sections and for laying the string of pipe on a ground surface.

The laying of pipe in ground trenches is an expensive and time consuming operation. This invention is concerned with minimizing the expense of such operation by providing apparatus for facilitating the assembly of pipe sections into a string and for preparing the trench bottom to receive and support the string of pipe in proper alignment within the trench.

An object of this invention is to provide an improved, movable support for supporting the end of the string in convenient position to have the next section of pipe joined to the string.

. Another object of this invention is to provide an improved, movable support defining an articulating train for accommodating curvature in the ground path for the pipe string.

A further object of this invention is to provide an improved, movable support for laying a pipe string in a trench having means for preparing the trench bottom surface for receiving and supporting the pipe string.

A still further object of this invention is to provide an improved movable apparatus for forming a pipe supporting bed at the bottom of a trench and for laying the pipe on said bed.

Still another object of this invention is to provide an improved pipe laying apparatus for forming a string from pipe sections having an enlarged bell at one end to define a joint with an adjacent pipe section.

These objects are obtained in a pipe laying sled havin g supporting runners and adapted to be pulled along a pipe trench by a suitable towing apparatus. The sled defines an upper pipe supporting surface inclined downwardly from the forward end toward the rearward end and having structure for supporting the enlarged bell end of one pipe section and the shank end of the additional section in axial alignment for the purpose of making the joint. At least one trailer sled is coupled to a main sled, in train, to extend the supporting surface and provide for articulation of the sled assembly. The sled may include means for lateral self-centering between the trench walls and for forming a ridge of loose dirt on the trench bottom to define a bed for supporting the pipe string.

DRAWINGS The novel features of the invention, as well as additional objects and advantages thereof, will be understood more fully from the following description when read in connection with the accompanying drawing, in which:

FIG. 1 is a top view of a preferred form of apparatus according to the invention;

FIG. 2 is a side view of the apparatus of FIG. 1; FIG. 3 is a perspective view of the apparatus of FIG.

FIG. 4 is an elevation view of the forward end of the apparatus of FIG. 1;

FIGS. 5 and 6 are fragmentary views of sectional views taken, respectively, along the Line 5-5 and Line 6-6 of FIG. 2 showing details of the pipe supporting surface;

FIG. 7 is a fragmentary sectional view taken along the Line 7-7 of FIG. 2;

FIG. 8 is a view of a section of pipe; and

FIG. 9 is a transverse view of a pipe trench showing the pipe and a supporting bed therefor.

DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred form of apparatus according to the invention, which is illustrated in the drawings, is particularly adapted for use with pipe sections of the type shown in FIG. 8 including an elongated shank 6 having an enlarged bell 7 at one end dimensioned for receiving the end portion 8 of an adjacent like section to form a compression joint. Such pipe sections are joined to form a string by forceably compressing the mating ends together to achieve the desired sealed joint. Each end portion 8 may be tapered to a diameter slightly smaller than the shank portion 6 which comprises most of the length of the pipe section.

As best seen in FIGS. 1, 2, and 3, the overall apparatus includes a main sled 10 and at least one trailer sled 11 which are coupled together in a trainlike manner as will be described. In practice at least two trailer sleds will most often be used although only one is required. The apparatus is designed to be towed or pulled along the pipe trench by means of any suitable towing apparatus; and may be pulled by a ditching machine which is preparing the trench ahead of the pipe laying apparatus. The leading or forward end of the apparatus is viewed at the right in FIGS. 1, 2, and 3 of the drawings.

The main sled 10 is supported on a pair of parallel runners 12 which may be fabricated of structural channels for example. The pipe supporting surface of the main sled is preferably defined by a forward roller section 13 at the forward end of the sled, and intermediate curved plate portion 14, and a rearward roller section 15.

The forward roller section 13 is supported on the runners 12 by means of

vertical legs

16 and 17, with appropriate transverse braces being provided for rigidity of structure. The rearward roller section 15 is supported on the rearward ends of the runners 12 by means of

vertical legs

18 and 19 with suitable braces again being provided for rigidity of structure. The two roller sections are interconnected by a pair of elongated cylindrical rods 20 which are secured to the tops of the side frames of the forward and rearward roller sections to define side rails for the pipe supporting surface. These rods 20 extend from the rearward end of the sled 10 to a point short of the forward end of the sled and bridge the intermediate space between the forward and rearward roller sections. The rods 20 may be secured to the roller sections by means of welding or in any other suitable manner.

The curved plate portion 14, as best seen in FIGS. 2 and 5, consists of an elongated plate section supported on the side rails 20 and being formed to define a concave cylindrical trough 24 between the side rails 20 and extending longitudinally between the two

roller sections

13 and 15. The side edges of the plate 14 are secured to the side rails by means of welding or in any other suitable manner.

The trough 24 is dimensioned to support and to confine laterally the enlarged bell end 7 of a pipe section during the assembly of the adjoining pipe section, the enlarged bell end being the exposed end of the last section to be joined to the string. The shank portion of the next section to be joined to the string is supported on the forward roller section 13; and, as best seen in FIG. 5, the rollers 23 of the roller section 13 define a supporting surface which lies above the base of the trough 24. This difference in elevation may be one or two inches for example, so that the shank portion 6 of the section of pipe being joined to the string is supported in generally axial alignment with the bell portion 7 of the section to which it is being joined. As best seen in FIG. 6, the rollers 25 of the rearward roller section 15 are disposed to define an upper supporting plane which coincides with the base of the trough 24, so that as the sled is moved forwardly from under the assembled pipe string, the bell joint will pass smoothly from the curved plate portion 14 on to the rearward roller section 15.

As seen in the figures, the trailer sled 11 can be considerably shorter than the main sled and is made up of a pair of parallel runners 27 supporting a roller section 28 on

vertical legs

29 and 30. This structure may be fabricated in any suitable manner, such as by welding, with suitable cross braces for rigidity if desired. In coupled relation with the main sled 10, the roller section 28 effectively provides a continuation of the rearward roller section 15. The forward end 31 of the roller section 28 is inclined downwardly and the rollers in this portion 31 define a plane inclined with respect to the plane of the main supporting surface to pick up the bell portion 7 of the pipe as the sled is moved forwardly relative to the pipe string.

The trailer sled 11 is coupled to the main sled 10 with a pair of parallel tow bars 35 which are pivotally connected to the forward legs 29 of the trailer sled 11, adjacent to the lower ends thereof, and to the vertical legs 19 of the main sled 10, adjacent to the upper ends thereof. The tow bars 35 are pivotally connected to the legs by means of horizontal pins or bolts, so that the tow bars swing about horizontal axes to provide for vertical articulation of the trailer sled 11 relative to the main sled 10. In this manner, the joined sleds will accommodate vertical undulations of the trench bottom or other surface upon which the pipe is being laid.

To provide for limited lateral articulation of the trailer sled 11 relative to the main sled 10, the forward ends of the tow bars are provided with longitudinally elongated slots 36 which receive the respective pivot pins of the main sled legs 19. The slots and pins, then, define lost motion connections between the tow bars and legs 19, permitting relative longitudinal movement so that the effective lengths of the tow bars relative to each other may be changed. In this manner, the trailer sled 11 may swing laterally out of longitudinal alignment with the main sled 10 to accommodate lateral curvature of the trench; yet, with the pair of tow bars 35, good longitudinal tracking is maintained.

As best seen in FIGS. 2, 3, and 7, the main sled 10 includes structure for centering the sled between the walls of the pipe trench. An assembly for yieldingly engaging the trench wall is mounted on each side of the pipe sled 10. These assemblies are identical; and only one such assembly will be described. As seen in the drawings, an elongated guide strap 40, preferably fabricated of a resilient metal, is supported between the

legs

16 and 17 extending generally parallel to the runner 12. The rearward end of the strap 40 is formed to define a bearing portion 41 to accommodate a pivot pin suitably supported on the leg 17 between brackets 42 for example. The forward end of the strap 40 is supported and guided within a C-shaped bracket 43 mounted on the leg 16 to permit longitudinal sliding of the strap 40 relative to the leg 17. A vertical leg 44 is secured between the runner l2 and the forward roller section 13 approximately equidistant from the

legs

16 and 17. A compression spring 45 is connected between the leg 44 and the strap 40 to urge the center portion of the strap outward relative to the end supports, and therefore to maintain an outwardly extending bow in the strap as viewed from the top of the sled. In this manner, when the sled is positioned within a pipe trench, the central portions of the straps 40, on either side of the sled, are urged outwardly into engagement with the side walls of the trench; and the straps are continuously and yieldingly urged outwardly to accommodate variations in the side walls and varying transverse dimensions between the side walls, with similar forces acting at each side of the sled to maintain a central position within the trench. As the bows in the straps 40 are increased or decreased, the supporting brackets 43 for the forward ends permit longitudinal sliding movement necessary to permit the changes in curvature.

As best seen in FIGS. 2, 3, and 4, the main sled 10 includes means for forming a ridge of loose dirt or other ground material to define a bed for supporting the string of pipe at the bottom of the trench. Such a ridge 9 is illustrated in FIG. 9 of the drawings, and is particularly desirable for initially supporting the pipe string where the string includes enlarged bells 7 or couplings at the joints. The ridge 9 of loose earth material will give way, as by spreading, at the joint 7 to provide for uniform support of the string along the entire length. The means for forming the ridge includes two pairs of

blades

47 and 48 which are secured in any suitable manner to the inner walls of the runners 12 and which extend inwardly toward each other to guide the loose material toward the central area between the runners. The lower edges of the blades may lie in the plane defined by the lower surface of the runners 12, or lower, to scrape the trench bottom and form the central ridge 9. While not shown in the drawings, it may also be desirable to provide means defining a transverse row of scarifying fingers to level any humps in the trench bottom and to loose or break up the earth material to a texture or size appropriate for forming the supporting ridge 9.

The operation of the above described apparatus will now be briefly summarized in connection with the laying of a string of pipe made up of sections of pipe of the type described and illustrated in FIG. 9. The sled assembly is positioned so that the curved plate portion 14 underlies the bell portion 7 of the last section of pipe joined to the string, which is then supported and confined by the trough 24. The string of pipe will be supported on the roller sections 28 of the trailer sleds 11 until the string will rest on the trench bottom some distance beyond the rearward end of the trailer sled l l.

The next section of pipe to be joined to the string is then placed on the roller section 13 of the sled with its bell end forward and the shank 6 being supported on the rollers 23. If the forward end of the sled 10 is approximately at ground surface level, the pipe section may be readily rolled from the ground surface onto the sled. This pipe section, guided by the side rails 20, is then pushed rearwardly on the roller section 13 toward the end of the string with the rollers 23 defining a supporting plane for the shank above the base of the trough 2d. The bell 7 at the end of the string is supported in the trough relative to the roller section 13, so that the shank portion of the pipe section to be joined is axially aligned with the bell. The end 8 of the pipe section is readily engaged with the bell 7 at the end of the string to make the compression joint.

When the joint is completed, the sled assembly is pulled forward by the ditching machine or other suitable apparatus a distance equivalent to the length of one pipe section, so that the bell portion of the pipe section just joined to the string is positioned in the trough 24. During this movement of the sled assembly, the bell of the preceding section will pass from the trough 24 onto rollers 25 of the roller section and when this bell passes beyond the sled 10, it will engage the inclined portion 311 of the roller section 28 to be supported by this section. When the forward end of the sled 10 meets the bell portion of the pipe section just joined to the string, the inclined forward end portion 26 of the roller section 13 will engage the bell to lift and support the bell in its movement toward the trough 24 as the sled is moved forward.

During the forward movement of the sled assembly, the guide straps 40 will maintain the leading end of the sled 10 generally centered relative to the side walls of the trench. If desired, an additional centering assembly can be provided toward the rearward end of the sled.

Also during the forward movement of the sled assembly, the

scraper blades

47 and 48 will form an elongated central ridge 9 of loose dirt along the trench bottom as best seen in FIG. 9. This ridge forms a bed for supporting the pipe string as it is laid on the trench bottom during the forward movement of the sled assembly. Since the bed is soft, being formed of pulverized material, the ridge will give way by spreading when it is engaged by a pipe bell 7, so that both the shank portions and the bell portions of the pipe string will be generally uniformly supported by the ridge, with the pipe in appropriately aligned position from the trench bottom. The supporting ridge 9 greatly minimizes the possibility that the bell joints will be broken or not provide a seal as the result of misalignment to adjacent sections.

Although the invention has been described with reference to a particular preferred embodiment, many changes and modifications will become apparent to those skilled in the art in view of the foregoing description which is intended to be illustrative and nonlimiting of the invention defined in the claims.

What is claimed is:

1. Pipe laying apparatus, adapted to be moved along a pipe receiving trench upon which a string of joined sections of pipe is being laid, comprising:

at least one frame having bottom runner means for sliding engagement with the surface and inclined main support means for supporting, in alignment, the last section of pipe joined to the string and the next section of pipe to be joined to the string; said main support means being inclined upwardly from the frame trailing end toward the frame leading end;

said main support means including a trough portion for supporting and laterally locating the enlarged coupling end of the last section of pipe joined to the string and aforward section raised relative to said trough portion for supporting the shank of the next section of pipe to be joined whereby the shank of the next section is supported in axial alignment with the supported coupling end;

said trough portion comprising a plate member supported on said frame defining a longitudinally extending concave trough for receiving the enlarged coupling end of a pipe section; and wherein said forward section defines a supporting surface lying above the base of said trough to support the shank portion of a pipe section in alignment with the coupling end of the last section joined to the string.

2. Pipe laying apparatus as set forth in claim 1 further including a rearward section for engaging and supporting the string of pipe; and wherein said forward and rearward pipe supporting sections are defined by roller means for engaging and supporting the pipe.

3. Pipe laying apparatus as set forth in claim ll including implement means mounted on said frame for forming a ridge of loose material at the bottom of said trench to provide a supporting bed for the string of pipe.

4. Pipe laying apparatus as set forth in claim 1 wherein said bottom runner means comprises at least one pair of spaced parallel runners; and blade means mounted on said runners, providing scraping edges in the plane of said runners for forming a ridge of said loose ground material between said runners to provide a supporting bed for the string of pipe.

5. Pipe laying apparatus as set forth in claim 1 including centralizing means for laterally centering the apparatus in the trench; said centralizing means comprising a guide member mounted on each side of said frame for lateral swinging movement into engagement with the walls of the trench; and spring means yieldably urging each of said guide members outwardly relative to said frame into engagement with the trench walls.

6. Pipe laying apparatus as set forth in claim 1 including centralizing means for laterally centering the apparatus in the trench; said centralizing means comprising longitudinal, outwardly bowed spring members mounted on each side of said frame; and spring means associated with each spring member for urging said member outward relative to said frame into engagement with the wall of a ground trench.

7. Pipe laying apparatus as set forth in claim 6 wherein each of said spring elongated members is pivotally attached at one end to said frame; and wherein the other end of said members is attached to said frame by means of a sliding coupling to permit longitudinal movement of said other end relative to said frame.

a pipe receiving trench upon which a string of joined sections of pipe is being laid, comprising:

at least one frame having bottom runner means for sliding engagement with the surface and inclined main support meansfor supporting, in alignment, the last section of pipe joined to the string and the next section of pipe to be joined to the string; said main support means being inclined upwardly from the frame trailing end toward the frame leading end;

said main support means including a trough portion for supporting and laterally locating the enlarged coupling end of the last section of pipe joined to the string and a forward section raised relative to said trough portion for supporting the shank of the next section of pipe to be joined whereby the shank of the next section is supported in axial alignment with the supported coupling end;

at least one trailer frame having bottom runner means and inclined pipe supporting means; said first named main frame and said trailer frame providing a generally aligned pipe supporting surface; said at least one trailer frame providing a pipe supporting surface between said main support means and the bottom of the trench;

means coupling said trailer frame to said main frame to provide for vertical and lateral articulation of said frame;

each of said trailer frames and said main frame includes roller means defining the pipe supporting surfaces; and wherein said trailer frame supporting surface includes a downwardly inclined forward edge to engage the enlarged diameter portions of the pipe sections.

9. Pipe laying apparatus as set forth in claim 8 wherein said coupling means comprises a pair of parallel tow bars pivotally connected to both the main frame and the trailer frame adjacent to the sides thereof, said tow bars being pivoted about horizontal axes;

and one end of each of said tow bars having a longitudinally elongated slot means defining a respective pivotal connection and permitting longitudinal dinally elongated slot at one end coacting with a horizontal pivot shaft to define a lost motion connection providing for limited lateral articulation of said trailer frame relative to said main frame.

12. Pipe laying apparatus as set fOIIHl in claim 8 mclu mg means mounted on sat main frame for laterally centering the apparatus in the trench.

13. Pipe laying apparatus, adapted to be moved along a pipe receiving trench upon which a string of 10 joined sections of pipe is being laid, comprising:

movement of the tow bar and pivot means to pro- I vide for limited lateral articulation of the trailer frame relative to the main frame.

10. Pipe laying apparatus as set forth in claim 8 wherein said coupling means includes a pair of laterally spaced tow bars pivotally connected between said main frame and the trailer frame; each end of the tow bar and the associated frame defining pivot means for vertical articulation of the trailer frame relative to the main frame;

and the pivot means on one end of each of said tow bars including means permitting relative longitudinal movement of the tow bar relative to the frame to provide for limited lateral articulation of the trailer frame relative to the main frame.

1 1. Pipe laying apparatus as set forth in claim 10 wherein each of said tow bars includes a longitu a main frame having bottom runner meansfor sliding engagement with the surface and inclined support means for supporting in alignment the last section of pipe joined to the string and the next section of pipe to be joined to the string; said support means being inclined upwardly from the frame trailing end toward the frame leading end;

said main frame inclined support means including forward and rearward sections defined by roller means for engaging and supporting the pipe, and a trough portion defined by a curved plate member mounted on said frame between said forward and rearward support sections for supporting and laterally confining the enlarged coupling end of the last pipe section joined; said forward support section defining a supporting surface lying above the base of said trough to support the shank portion of the next pipe section to be joined in alignmerit with the coupling end of the last section joined to the string;

at least one trailer frame having bottom runner means and an inclined pipe supporting surface defined by roller means, said main frame and said at least one trailer frame providing a generally aligned pipe supporting surface, with said at least one trailer frame providing a pipe supporting surface between said main frame and the bottom of the trench;

means coupling said trailer frame to said main frame comprising a pair of parallel tow bars pivotally connected to both the main frame and the trailer frame adjacent to the sides thereof; said tow bars being pivoted about horizontal axis, and one end of each of said tow bars having a longitudinally elongated slot means defining a respective pivotal connection and permitting longitudinal movement of the tow bar and pivot means to provide for limited lateral articulation of the trailer frame relative to the main frame;

centralizing means mounted on said main frame for centering the apparatus in the trench; said centralizing means comprising a guide member mounted on each side of said frame for lateral swinging movement, and spring means yieldably urging each of said guide members outwardly relative to said frame into engagement with the trench walls;

and implement means mounted on said frame for forming a ridge of loose material at the bottom of said trench between said runners to provide a supporting bed for the string of pipe.

Claims

1. Pipe laying apparatus, adapted to be moved along a pipe receiving trench upon which a string of joined sections of pipe is being laid, comprising: at least one frame having bottom runner means for sliding engagement with the surface and inclined main support means for supporting, in alignment, the last section of pipe joined to the string and the next section of pipe to be joined to the string; said main support means being inclined upwardly from the frame trailing end toward the frame leading end; said main support means including a trough portion for supporting and laterally locating the enlarged coupling end of the last section of pipe joined to the string and a forward section raised relative to said trough portion for supporting the shank of the next section of pipe to be joined whereby the shank of the next section is supported in axial alignment with the supported coupling end; said trough portion comprising a plate member supported on said frame defining a longitudinally extending concave trough for receiving the enlarged coupling end of a pipe section; and wherein said forward section defines a supporting surface lying above the base of said trough to support the shank portion of a pipe section in alignment with the coupling end of the last section joined to the string.

3. Pipe laying apparatus as set forth in claim 1 including implement means mounted on said frame for forming a ridge of loose material at the bottom of said trench to provide a supporting bed for the string of pipe.

8. Pipe laying apparatus, adapted to be moved along a pipe receiving trench upon which a string of joined sections of pipe is being laid, comprising: at least one frame having bottom runner means for sliding engagement with the surface and inclined main support means for supporting, in alignment, the last section of pipe joined to the string and the next section of pipe to be joined to the string; said main support means being inclined upwardly from the frame trailing end toward the frame leading end; said main support means including a trough portion for supporting and laterally locating the enlarged coupling end of the last section of pipe joined to the string and a forward section raised relative to said trough portion for supporting the shank of the next section of pipe to be joined whereby the shank of the next section is supported in axial alignment with the supported coupling end; at least one trailer frame having bottom runner means and inclined pipe supporting means; said first named main frame and said trailer frame providing a generally aligned pipe supporting surface; said at least one trailer frame providing a pipe supporting surface between said main support means and the bottom of the trench; means coupling said trailer frame to said main frame to provide for vertical and lateral articulation of said frame; each of said trailer frames and said main frame includes roller means defining the pipe supporting surfaces; and wherein said trailer frame supporting surface includes a downwardly inclined forward edge to engage the enlarged diameter portions of the pipe sections.

9. Pipe laying apparatus as set forth in claim 8 wherein said coupling means comprises a pair of parallel tow bars pivotally connected to both the main frame and the trailer frame adjacent to the sides thereof, said tow bars being pivoted about horizontal axes; and one end of each of said tow bars having a longitudinally elongated slot means defining a respective pivotal connection and permitting longitudinal movement of the tow bar and pivot means to provide for limited lateral articulation of the trailer frame relative to the main frame.

10. Pipe laying apparatus as set forth in claim 8 wherein said coupling means includes a pair of laterally spaced tow bars pivotally connected between said main frame and the trailer frame; each end of the tow bar and the associated frame defining pivot means for vertical articulation of the trailer frame relative to the main frame; and the pivot means on one end of each of said tow bars including means permitting relative longitudinal movement of the tow bar relative to the frame to provide for limited lateral articulation of the trailer frame relative to the main frame.

11. Pipe laying apparatus as set forth in claim 10 wherein each of said tow bars includes a longitudinally elongated slot at one end coacting with a horizontal pivot shaft to define a lost motion connection providing for limited lateral articulation of said trailer frame relative to said main frame.

12. Pipe laying apparatus as set forth in claim 8 including means mounted on said main frame for laterally centering the apparatus in the trench.

13. Pipe laying apParatus, adapted to be moved along a pipe receiving trench upon which a string of joined sections of pipe is being laid, comprising: a main frame having bottom runner means for sliding engagement with the surface and inclined support means for supporting in alignment the last section of pipe joined to the string and the next section of pipe to be joined to the string; said support means being inclined upwardly from the frame trailing end toward the frame leading end; said main frame inclined support means including forward and rearward sections defined by roller means for engaging and supporting the pipe, and a trough portion defined by a curved plate member mounted on said frame between said forward and rearward support sections for supporting and laterally confining the enlarged coupling end of the last pipe section joined; said forward support section defining a supporting surface lying above the base of said trough to support the shank portion of the next pipe section to be joined in alignment with the coupling end of the last section joined to the string; at least one trailer frame having bottom runner means and an inclined pipe supporting surface defined by roller means, said main frame and said at least one trailer frame providing a generally aligned pipe supporting surface, with said at least one trailer frame providing a pipe supporting surface between said main frame and the bottom of the trench; means coupling said trailer frame to said main frame comprising a pair of parallel tow bars pivotally connected to both the main frame and the trailer frame adjacent to the sides thereof; said tow bars being pivoted about horizontal axis, and one end of each of said tow bars having a longitudinally elongated slot means defining a respective pivotal connection and permitting longitudinal movement of the tow bar and pivot means to provide for limited lateral articulation of the trailer frame relative to the main frame; centralizing means mounted on said main frame for centering the apparatus in the trench; said centralizing means comprising a guide member mounted on each side of said frame for lateral swinging movement, and spring means yieldably urging each of said guide members outwardly relative to said frame into engagement with the trench walls; and implement means mounted on said frame for forming a ridge of loose material at the bottom of said trench between said runners to provide a supporting bed for the string of pipe.