US3715889A

US3715889A - Trench shoring machine

Info

Publication number: US3715889A
Application number: US00204437A
Authority: US
Inventors: D Bixler; R Corey
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-12-03
Filing date: 1971-12-03
Publication date: 1973-02-13
Anticipated expiration: 1990-02-13

Abstract

Upper and lower generally rectangular boxes, affixed together, are disposed in a trench to provide a safe working space for workmen installing underground pipe. Probing side plates at the front of the boxes are movable forward and backwards hydraulically to control collapse of the trench wall ahead of the box assembly. An upstanding pusher wall at the rear end of the upper box is hydraulically drivable rearwardly to push against fill in the trench behind the box assembly whereby, upon compaction, the box assembly is pushed forward in the trench. A shroud affixed to the rear of the lower box below the pusher wall assembly covers and protects the pipe from separation as the box assembly is moved forward. The box side walls are tapered inwardly toward the rear to minimize soil adhesion resistance to forward movement of the box assembly. Hydraulic lifting pads under the assembly assist in steering and maintenance of proper leveling and grade of the box assembly. Balancing and phasing means are provided in the hydraulic system. A built-in greasing system is employed.

Description

0 United States Patent 1 1 1 1 3,715,889 Bixler et al. 1 Feb. 13, 1973 [54] TRENCH SHORING MACHINE [76] Inventors: Donald Bixler, 9520 Copley Dr., ln- [57] ABSTRACT dlallapolls, Illd- 46260; Robert Upper and lower generally rectangular boxes, affixed y 6933 T011816) DR, lndltogether, are disposed in a trench to provide a safe allapollslllld- 46256 working space for workmen installing underground [22] Filed: Dec 3, 1971 pipe. Probing side plates at the front of the boxes are movable forward and backwards hydraulically to con- [21] Appl- 204,437 trol collapse of the trench wall ahead of the box assembly. An upstanding pusher wall at the rear end of 52 us. (:1. ..6l/41 A, 6l/63 the upper box is hydraulically drivable reerwardly 51 1m. (:1. .E2ld 5/12 P against fill in the trench behind the box assembly [58] Field of Search ..61/41, 41 A, 63, 84, 85, 72.2 whereby, p compaction, the box assembly is pushed forward in the trench. A shroud affixed to the [56] References Ci d rear of the lower box below the pusher wall assembly covers and protects the pipe from separation as the UNITED STATES PATENTS box assembly is moved forward. The box side walls are 2,908,140 10/1959 Everson ..61/41 A tapered inwardly Ward the Year minimize 30g9,310 5/1963 Toni "61/41 A hesion resistance to forward movement of the box as- 3,473,336 10 1969 Toni "51 4 A sembly. Hydraulic lifting pads under the assembly 3,479,827 11/1969 Morrice.... 61/63 X assist in steering and maintenance of proper leveling 3,543,522 12/1970 Torti l i ..6l/85 and rade of the box assembly. Balancing and phasing 3,608,319 9/1971 Quitadamo ..6l/63 Primary ExaminerDennis L. Taylor Attorney-Joseph A. Naughton, Jr.

means are provided in the hydraulic system. A built-in greasing system is employed.

21 Claims, 8 Drawing Figures PATENTEUFEB l 3 I975 sum 2 0F 3 FIG. 5

FIG. 4

TRENCH SHORING MACHINE BACKGROUND OF THE INVENTION aware will be provided at the end of this specification.

Some of the references are rather primitive by todays standards, but that is understandable in view of the early dates at which such references came into existence. More recent developments shown in the references include shoring machines which use a hydraulic power supply from an external source for driving hydraulic pistons and thereby making the shoring machines self-propelled in the trench. However, to provide adequate working space in the trench and yet adequately protect the workmen both from the digging equipment and from cave-ins, the prior art machines are of substantial length and some, such as the Torti machines, are closed on top. These characteristics add to weight, thus making the machine more difficult to transport on a truck or trailer to the work site, and more difficult to move and control in the trench. Also there have been problems encountered as a result of adhesion of soil to the sides and rear of the shoring machines as they move forward or as the pusher element is retracted forwardly, with attendant problems of troublesome advancement in the trench and tendency to separate assembled lengths of pipe. The present invention is directed to overcoming these problems encountered with prior art equipment.

SUMMARY OF THE INVENTION Described briefly, in a typical embodiment of the present invention, a shoring machine is somewhat boxlike assembly having a generally upstanding pusher wall at the upper rear end thereof, and which is movable back and forth by powered actuator means. The lower rear wall is stationary with respect to the side walls and is provided with a shrouded opening to protect the work which has been done.

Powered probing plates on the sides of the machine at the front end are movable forwardly and retractable independent of the main body of the shoring machine, to support the sides of the trench as it is being dug and continue such support during forward movement of the shoring machine itself by actuation of the pusher wall rearwardly. Powered selectively operable lifting pads are provided at the bottom to aid in steering the assembly and to maintain the proper level of the box and hold the proper grade.

Means are provided to assure equal movement of actuator means, simplification of lubrication, and minimize weight, and remove water from the trench.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of a shoring machine according to a typical embodiment of the present invention.

FIG. 2 is a side elevational view thereof.

FIG. 3 is a section therethrough taken at line 3-3 in FIG. 1 and viewed in the direction of the arrows.

FIG. 4 is a front end view thereof.

FIG. 5 is a fragmentary front end view showing the assembly tilted by one of the lifting pads, and with the front wall of the lower box of the machine omitted to show the pad operating cylinders.

FIG. 6 is a schematic hydraulic diagram of the machine.

FIG. 7 shows the machine in a trench.

FIG. 8 is a schematic mechanical diagram of the probing plate guide greasing system.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in detail, as shown in FIG. 1, the shoring machine is a generally rectangular structure, and as indicated in FIG. 2, may be regarded as a box assembly including a lower box 11 and an upper box 12 secured together. Neither of these socalled boxes has a top or bottom. The lower box has a rear end wall 13 with a shroud 14 affixed thereto and extending rearwardly therefrom covering a portion of the'sewer pipe 16 which has been installed by workmen working in the unit at 15. The lower box has a front end wall 17 (FIG. 3). The upper box is open in front.

The upper box 12 has a pusher unit therein including a rear end wall 18 which is movable rearwardly in the direction of arrow 19 and forwardly in the direction of arrow 21 by hydraulic cylinders 22 (FIG. 3). The pusher unit includes a pair of side walls 23 and a top wall 24 affixed to pusher wall 18, this entire assembly being movable as a unit independent of the box assembly.

At the front of the boxes and immediately outside of the side walls of the boxes there are probing plates. While upper probing plates in one form were used by us on a predecessor machine more than a year ago, we have since determined that additional probing plates are needed. For example, according to the present invention, on each side there are upper, intermediate, and

lower probing plates

26, 27 and 28, respectively. Each of these plates is drivable forwardly in the direction of arrow 21 and rearwardly in the direction of arrow 19 by means of hydraulic cylinders 29 (FIG. 3).

Probing plate 26 is affixed to the front end of each of three

tubes

31, 32, and 33, as at 34, for example. Tube 1 31 serves as a guide tube linearly slidable inside a guide sleeves 36 affixed in the wall 37. The structure of wall 37 to facilitate such attachment can include a plurality of channel sections 38 extending lengthwise of the machine between the inner and

outer wall sheeting

39 and 41, respectively and welded thereto. Vertical webs 42 are provided between the channels and the wall sheeting and are welded to the channels. This is also shown schematically in FIG. 8 wherein two of the vertical webs (identified 42A and 42B) cooperate with the wall sheeting and channels 38 to form a plurality of grease boxes (as at 40 for tube 31), one for each tube. A separate grease line is provided for each of the boxes, and the six lines for the six boxes shown in FIG. 8 terminate in the group of grease fittings 45 conveniently located at the top of the wall 37. Each of the guide sleeves such as 36 opens into a respective one of the grease boxes and, of course, the guide tubes such as 31 are openly exposed to the grease packing the boxes through which they extend. The guide sleeves such as 36 can be welded to the webs 42. The same kind of mounting can be provided for the

sleeves

43 and 44 guiding the

tubes

32 and 33, respectively. A universal joint 46 provides the connection between the tube 32 and the piston rod 37 of cylinder 29 for probing plate 26. Therefore, as the cylinder 29 drives the probing plate 26 forward or backward,

tubes

31 and 33 in

sleeves

36 and 44 serve guiding functions and while tube 32 is guided in sleeve 43, the universal joint 46 removes any possibility of binding due to any misalignment which might exist or develop between the tube 32 and piston rod 47. Cylinder 29 is confined in the wall 37 by webs such as 42, but is not welded thereto, the rear end thereof being anchored to pin 48 which may be mounted in two of the channel members 38.

For the pusher wall, as best shown in FIG. 3, there are two right-hand pusher cylinders 22 each pinned as at 49 to brackets 51 affixed to the inner wall 39 and thereby to the elongated channels 38 of the upper box assembly. The piston rods 52 are connected by universal joints 53 to the pusher wall 18, with whatever the enforcement may be needed at the region of thrust. An upper guide tube 56 is affixed to the pusher wall as is a lower guide tube 57 and, as described for the guide tubes of the probing plates, there are short sections of guide sleeves affixed in the wall 37 tittingly and slidingly receiving these

guide tubes

56 and 57. The same construction is provided on the left-hand side of the shoring machine. The total of four guide tubes in guide sleeves therefor maintains proper alignment of the pusher wall as it is pushed rearwardly by the cylin ders 22 and, as it is retracted to permit fill to be deposited behind the shoring machine.

To assist in steering and leveling and maintaining the proper grade with the shoring machine, lifting

pads

61 and 62 are provided near the front of the machine. Each of these pads ishinged at its front end to the lower front end of the shoring machine as at hinge pin 63 for pad 62 in FIG. 3. Each pad also has an actuating cylinder as at cylinder 64 for pad 62. The upper end of this cylinder is pinned at 66 to a bracket affixed to crossmember 67 affixed to the inside wall of the shoring machine. The piston rod 68 is pinned at 69 to a bracket affixed to the pad 62. FIG. 3 and FIG. 4 show both pads actuated by extending the piston rods of their respective cylinders. FIG. shows only the right-hand pad actuated to illustrate the tilting function which can be effected. The pads are retracted in FIGS. 1 and 2.

In the lower box, forprobing plate 28 both of the mounting tubes are driven by cylinders 29, in contrast to the arrangement for the upper plates in the upper box wherein for each there are two guide tubes and-a pushing tube.

As shown in FIGS. 1 and 2, there is a cross over walkway and observation platform 71 near the front end of the upper box. As best shown in FIGS. 2 and 3, there is an operators platform 72 near the rear end of the machine but this platform is omitted from FIG. 1 in order to enable showing the top cover 24 of the pusher wall assembly. At the operators platform there is a plurality of controls as indicated onlysymbolically by handle lever 73 in FIG. 2. The hydraulic diagram of FIG. 6 shows the various controls and associated hydraulic circuitry.

Referring now to FIG. 6, a reservoir 74 of hydraulic fluid serves

constant displacement pumps

76 and 77. Each of these pumps has a pressure relief valve associated therewith and return line to the reservoir. Pump 76 has a pressure output on line 78 to the first master control valve 79. This valve is shown in a neutral position blocking flow from a pump 76 to a series of probing plate control valves 81.

Similarly, pump 77 has a pressure output on line 82 connected to a second master control valve 83. The connection to this valve is such that, in the neutral position shown, pressure is provided from pump 77 through

valves

83, 84, 86 and 87 back to the reservoir on return line 88.

Valve 79, when shifted to the left, will direct pressure from pump 76 through each of the eight valves 81 for the probing plates, back to the reservoir on return line 89. Each of the valves 81 is shiftable one step to the left from the neutral position shown, to provide for extension of the piston rod of the corresponding cylinder 29, or is shiftable one step to the right to provide retraction of the piston rod. Upon shifting the valve two steps to the left, chambers at both ends of the piston communicate with one another through the valve and the piston can move either way therein, depending upon the load thereon. This is a floating position.

When valve 83 is in the position shown, valve 84 can be shifted to the left to extend the piston rods from the respective push cylinders 22, and shifting the valve to the right will serve to retract the piston rods in cylinders 22. Moving either of the lift

cylinder control valves

86 or 87, to the left will extend the piston rod of the corresponding lift cylinder; and moving the valve to the right will retract the piston rod of the corresponding lift cylinder.

Shifting the first master control valve 79 to the right will provide pressure from pump 76 through valve 79, line 91 and check valve 92 to the second control valve 83. In this position it can supplement the supply from pump 77. Similarly, shifting the second master control valve 83 to the left will provide supply from the pump 77 through valve 83, line 93 and check valve 94 to valve 79 to supplement the supply thereto from pump 76.

Four hydraulically driven rotary motors 96 of fixed displacement have commonly connected shafts and each has an input port hydraulically connected to a port of one of the push cylinders. Each input port is also connected through one of the relief valves 97 to the

return line

98, 88 to the sump 74. The comparatively positive and fixed displacement, and mechanical inter-connection of these motors contributes to uniform travel of the piston rods of the various push cylinders 22. Thus, they serve as a sort of flow divider or equalizer. The P4759 flow divider produced by Delta Mfg. Co. was used for this purpose.

The possibility of using both

pumps

76 and 77 to serve a set of valves provides an effective pumping source of volumetric capacity twice that available from a single one of the pumps.

OPERATIONS In the operation of the apparatus, and referring to FIG. 7, a conventional digging machine makes a hole in the ground of the proper depth for the work to be done. While the machine is useful for various kinds of work, one example is the laying of sewer pipe. For this purpose, the hole is dug to the depth at which the pipe is to be laid. Then the shoring machine is lowered into the hole by the use of a crane and appropriate connecting cables. The workmen then climb down inside the machine to the bottom of the trench. Lengths of sewer pipe are lowered individually by a crane when needed through the open top to the workmen below. They assemble a length of pipe with the preceding length, a portion of which is shown projecting out under the rear end shroud 14. Meanwhile backfill material is moved into the hole behind the shoring machine at 102, by a shovel, dozer or other equipment. The probing

plates

26, 27, and 28 are moved forward hydraulically as the pipe assembly progresses, to prevent collapse of the bank of the trench ahead of the machine, as the trench is lengthened by the digging machine. Typically the probing plate drive cylinders have a stroke of about 6 feet, while the length of the working space in the machine and in which the workmen can work is approximately l4 feet. The front wall of the space is approximately 6 feet high.

When the length of pipe has been installed, the valves for the probing plates are placed in the furthermost position to the left (FIG. 6), placing the cylinders in the floating condition. Valve 84 (FIG. 6) is shifted to the left which applies pressure to the push side of the push cylinders 22. This forces the pusher wall to the rear in the direction of arrow 19 against the flll material which has been placed behind the shoring machine. This compacts the material and, when sufficient compaction has been established, additional travel of the pusher wall with respect to the shoring machine will thrust the shoring machine forwardly in the direction of arrow 21. As it so moves, the probing plates float toward their original retracted position. In the event the fill is so loose as to fail to provide sufficient resistance to move the machine forwardly the desired amount for installation of the next length of pipe, the pusher wall can be retracted, additional fill moved in behind it, and the process repeated. Eventually the machine will have been moved forward sufficiently for addition of another length or two of sewer pipe.

Once forward movement of the machine to the desired extent has been accomplished, valve 84 is shifted to the neutral position shown in FIG. 6, and one or more of the valves for the probing plates can be shifted as needed to extend the probing plates in the direction of arrow 21 and thus protect against cave-ins of the trench wall ahead of the machine for an additional 6 feet or so. As suggested above, if the master control valve 83 is moved to the left, twice the volume of hydraulic fluid available with the one pump can be provided, to double the speed at which the advance of the probing plates can be accomplished.

During the advancement of the shoring machine, if some adjustment is needed in the attitude or direction thereof,

valve

86 or 87 can be shifted as needed to operate one or both of the lifting pads.

If water in the trench bottom is a problem, a pump 106 driven by hydraulic motor 104 and having water intake hose 107 connected to its intake, is employed. The hose is extended to an intake screen 108 at the bottom of the trench and ahead of the machine, or it may be located wherever desired to best serve its purpose of keeping the trench dry. Valve 109 controls motor 104.

The reservoir and pumping equipment for the hydraulic fluid may be on a separate self-propelled or tractor-drawn wagon on the surface of the ground at the side of the trench, with appropriate plumbing to the control desk 72.

As best shown in FIG. 1, the probing plates are immediately outside the outside wall sheets of the machine. The spacing between the walls at the front is greater than at the rear. The pusher unit is within the outer wall sheets at the rear, as best shown in FIG. 1. Thus, in addition to the fact that there is 'a greater horizontal dimension between the outer wall sheets at the front than at the rear, thus providing a taper of the box toward the rear, the arrangement of the probing plates outside and the pusher unit to the inside, further emphasizes the tapered aspect, facilitating forward movement of the box in the trench. In addition, because of the taper, the front edges of the probing plates are farther apart horizontally when the plates are extended, than when the plates are retracted. Therefore, as the shoring machine is pushed ahead, and the probing plates float, the machine is moved into a space which is actually wider than is the front end of the machine itself with the plates retracted.

The facts that the pusher wall is above the aperture in the rear of the machine, and the shroud covering the aperture at the rear extends rearwardly the full extent of the pusher wall travel, assures that there will be no adhesion of back fill material or soil to the pipe. The benefit of this is avoidance of pulling joints apart during forward movement of the machine.

It can be seen that the shoring machine of the present invention might employ expanded metal for the side plates to afford protection of the men working in the machine, and yet secure a substantial weight saving. The various horizontal struts provide a rather open construction of the assembly, and substitution of longer struts would facilitate widening the overall assembly, and vice versa.

The employment of universal joints at the end of the pushing rams adjusts for any unequal movement of the side pushing rams. If, on the return stroke, one piston bottoms out before another one, continued supply of hydraulic fluid to the other pistons will return them to the home or bottom out condition so that they can all advance together from the same position upon commencement of the next extension of the pusher unit and are, therefore, starting in phase with each other. For the piston which bottoms-out" first, any pressure build up resulting from fluid leakage through the motor 96 associated therewith, while the remaining pistons continue to move, can escape through that one of the pressure relief valves 97 associated with the cylinder which has bottomed out." The pressure setting for valves 97 is preferably below the pressure setting for the relief valves at the pumps. This setting will depend on the size and weight and performance requirements of the equipment.

The prior art patents known to us and referred to above are United States patents as follows:

654,426 Washington July24, 1900 977,016 Johnson November 29, i910 1,234,716 Bager July 31,1917 1,305,270 Farrar June 3, 1919 1,817,367 Greiman August 4, 1931 1,896,433 Windeknecht February 7, 1933 2,633,713 Shields April 7, 1953 2,865,178 Wicke December 23, 1958 2,866,320 Bazzell December 30, 1958 2,908,140 Everson, Jr. October 13, 1959 2,922,283 Porter January 26, 1960 3,089,310 Torti May 14, 1963 3,l59,978 De Lillo December 8, 1964 3,204,415 Hill, Jr. et al September 7, 1965 3,377,806 Morrice April 16, I968 3,420,065 l-loll January 7, 1969 3,473,336 Torti October 21, 1969 3,479,827 Morrice November 25, 1969 While the invention has been disclosed and described in some detail in the drawings and foregoing description, they are to be considered as illustrative and not restrictive in character, as other modifications may readily suggest themselves to persons skilled in this art and within the broad scope of the invention.

The invention claimed is:

1. A trench shoring machine comprising:

a base frame supportable on the bottom of a trench and having horizontally spaced upstanding side walls disposed to prevent collapse of the trench bank into the space at the bottom of the trench between said side walls;

pusher means including a generally upstanding pusher wall transverse to said side walls at the upper rear end of said base frame and linearly movable with respect to said base frame;

a lower rear end wall on said base frame and fixed with respect to said side walls and having an opening therein to accommodate forward movement of said base frame lengthwise in said trench without disturbance of work completed in said trench between said side walls.

2. The shoring machine of claim 1 wherein:

said pusher means include actuator means mounted on said base frame and operable, when actuated, to drive said pusher wall rearwardly with respect to said base frame to a point of substantial rearward projection therefrom;

said rear end wall having a shroud extending rearwardly under a portion of the region of rearward projection of said pusher wall and around the upper margin of said opening to cover said work projecting through said opening and to preclude such adhesion of soil behind said frame to said frame and said work as would disturb said work as said frame is moved forward lengthwise in the trench.

3. The combination of claim 2 wherein:

said shroud is a downwardly and rearwardly opening hood for coverage of the top and sides of the said work without complete encirclement of the work.

4. The machine of claim 1 wherein:

the spacing between said side walls is greater at the front end of said base frame than at the rear end of said base frame to alleviate frictional resistance from horizontal soil pressure during forward movement of said frame.

5. The machine of claim 1 and further comprising:

first and second lifting pads disposed at the bottom of said base frame and mounted thereto for operation from' first positions between said side walls to second positions inclined downwardly and rear-- wardly from the bottom of said base frame. The machine of claim 5 and further comprising:

first and second actuator means coupled to said base frame and coupled respectively to said first and second pads and operable independently of each other for obtaining different extents of downward inclination to assist in steering said base frame as it moves forwardly in said trench.

7. The combination of claim 1 wherein said pusher means include:

a plurality of slides and a plurality of guides mounted respectively to said pusher wall and to said base frame, said slides being guidingly received in said guides for linear movement of said slides rearwardly and forwardly on said base frame, and

linear actuator means mounted to said base frame and coupled to one of said slides to drive said one slide, and thereby said pusher wall, rearwardly, from a retracted position to an extended position.

8. The combination of claim 7 wherein said pusher means include:

a universal joint connecting one of said slides to said pusher wall.

9. The combination of claim 8 wherein said linear actuator means include:

a first cylinder mounted to one of said side walls and having a piston rod connected to one of said slides; and

a second cylinder mounted to the other of said side walls and having a piston rod connected to another of said slides,

both of said cylinders being double acting,

a source of hydraulic pressure,

valve ,means operable in an advance position to supply hydraulic fluid from said source to one side of a piston in each of said cylinders to extend said pusher wall to drive said base frame forward;

said valve means being operable in a retract position to supply hydraulic fluid to the opposite side of said piston in each of said cylinders and release fluid on said one side of said piston, to retract said pusher wall,

and equalizing means operable to establish uniform movement for both of said pistons during movement of said pusher wall.

10. The combination of claim 7 wherein:

said side walls at the upper rear end of said base frame include outer side plates; and

said pusher means include outer side walls disposed immediately inside said outer side plates when said pusher wall is retracted.

11. The combination of claim 10 wherein:

said pusher means include a top wall, said side and top walls of said pusher means being joined to top and side margins, respectively, of said pusher wall.

12. The combination of claim 11 wherein:

said base frame has a lower front end wall extending up to a level above the level of the top of the opening in said lower rear end wall.

13. The combination of claim 1 and further comprising:

probing plates, one of said platesbeing located at the front of each of said side walls,

said plates being movable forwardly independently of said side walls to control collapse of trench walls ahead of said side walls.

14. The combination of claim 13 wherein:

each of said probing plates overlaps a portion of the side wall at which it is mounted, both before and after forward movement of said plate.

15. The combination of claim 14 and further comprising:

plate drive means coupled to said plates;

said pusher means including pusher drive means coupled to said pusher wall, and

control means coupled to said plate drive means and to said pusher drive means to enable simultaneous powered forward movement of said plates and pusher wall with respect to said base frame, and simultaneous rearward movement of said plates and pusher wall with respect to said base frame.

16. The combination of claim 14 wherein:

said pusher drive means include hydraulic actuators, and a source of hydraulic pressure therefor, and

' said plate drive means including hydraulic probing plate drive actuators, and a source of hydraulic pressure therefor;

said control means include a first control valve having a first condition hydraulically locking said actuators for said pusher drive means, and having second and third positions for respectively extending and retracting said pusher wall; and

said control means include additional control valves, each having a first position hydraulically locking the said probing plate drive actuator coupled thereto, and each having second and third positions for respectively power retracting and power extending the probing plate drive actuator coupled thereto, and each having a fourth position hydraulically neutralizing said probing plate drive actuator coupled thereto to permit the probing plate associated therewith to float in accord with external loads encountered thereby.

17. A trench shoring machine comprising:

a base frame supportable on the bottom of a trench and having horizontally spaced upstanding side walls disposed to prevent collapse of the trench bank into the space between said walls;

pusher means at the upper rear of said base frame and movable rearwardly and forwardly with respect to said base frame;

probing plates at the front of said base frame immediately outside the outer faces of said side walls from a point near the bottom of said base frame to a point near the top of said base frame, said probing plates being movable forwardly and rearwardly with respect to said base frame.

18. The shoring machine of claim 17 wherein:

said pusher means include pusher drive means; and

plate drive means are connected to said plates.

19. The machine of claim 18 wherein:

said pusher drive means include hydraulic actuators, and a source of hydraulic pressure therefor, and said plate drive means include hydraulic probing plate drive actuators, and a source of hydraulic pressure therefor;

the machine further comprising control means including a first control valve having a first condition hydraulically locking said actuators for said pusher drive means, and having second and third positions for respectively extending and retracting said pusher means; and said control means lllClUdll'lg additional control valves, each having a first position hydraulically locking the said probing plate drive actuator coupled thereto, and each having second and third positions for respectively power retracting and power extending the probing plate drive actuator coupled thereto, and each having a fourth position hydraulically neutralizing said probing plate drive actuator coupled thereto to permit the probing plate associated therewith to float forwardly or rearwardly in accordance with external loads encountered thereby.

20. A method of shoring a trench including the steps of placing a shoring machine inside a trench, projecting separately movable probing plates forward from the sides of said shoring machine adjacent the trench banks in front of the machine;

projecting a pusher wall from the rear of said machine against fill in the trench behind the machine and thereby moving the machine forward, and permitting the probing plates to remain in position with respect to the trench wall as the shoring machine is pushed forward by the pusher wall; and retracting the pusher wall and extending the probing plates forward again from the front of the machine as the machine remains at rest in the trench. 21. The method as set forth in claim 20 and further comprising the step of:

depressing movable support means at the bottom of the shoring machine against the bottom of the trench to raise the front of the shoring machine.

Claims

1. A trench shoring machine comprising: a base frame supportable on the bottom of a trench and having horizontally spaced upstanding side walls disposed to prevent collapse of the trench bank into the space at the bottom of the trench between said side walls; pusher means including a generally upstanding pusher wall transverse to said side walls at the upper rear end of said base frame and linearly movable with respect to said base frame; a lower rear end wall on said base frame and fixed with respect to said side walls and having an opening therein to accommodate forward movement of said base frame lengthwise in said trench without disturbance of work completed in said trench between said side walls.

2. The shoring machine of claim 1 wherein: said pusher means include actuator means mounted on said base frame and operable, when actuated, to drive said pusher wall rearwardly with respect to said base frame to a point of substantial rearward projection therefrom; said rear end wall having a shroud extending rearwardly under a portion of the region of rearward projection of said pusher wall and around the upper margin of said opening to cover said work projecting through said opening and to preclude such adhesion of soil behind said frame to said frame and said woRk as would disturb said work as said frame is moved forward lengthwise in the trench.

3. The combination of claim 2 wherein: said shroud is a downwardly and rearwardly opening hood for coverage of the top and sides of the said work without complete encirclement of the work.

4. The machine of claim 1 wherein: the spacing between said side walls is greater at the front end of said base frame than at the rear end of said base frame to alleviate frictional resistance from horizontal soil pressure during forward movement of said frame.

5. The machine of claim 1 and further comprising: first and second lifting pads disposed at the bottom of said base frame and mounted thereto for operation from first positions between said side walls to second positions inclined downwardly and rearwardly from the bottom of said base frame.

6. The machine of claim 5 and further comprising: first and second actuator means coupled to said base frame and coupled respectively to said first and second pads and operable independently of each other for obtaining different extents of downward inclination to assist in steering said base frame as it moves forwardly in said trench.

7. The combination of claim 1 wherein said pusher means include: a plurality of slides and a plurality of guides mounted respectively to said pusher wall and to said base frame, said slides being guidingly received in said guides for linear movement of said slides rearwardly and forwardly on said base frame, and linear actuator means mounted to said base frame and coupled to one of said slides to drive said one slide, and thereby said pusher wall, rearwardly, from a retracted position to an extended position.

8. The combination of claim 7 wherein said pusher means include: a universal joint connecting one of said slides to said pusher wall.

9. The combination of claim 8 wherein said linear actuator means include: a first cylinder mounted to one of said side walls and having a piston rod connected to one of said slides; and a second cylinder mounted to the other of said side walls and having a piston rod connected to another of said slides, both of said cylinders being double acting, a source of hydraulic pressure, valve means operable in an ''''advance'''' position to supply hydraulic fluid from said source to one side of a piston in each of said cylinders to extend said pusher wall to drive said base frame forward; said valve means being operable in a ''''retract'''' position to supply hydraulic fluid to the opposite side of said piston in each of said cylinders and release fluid on said one side of said piston, to retract said pusher wall, and equalizing means operable to establish uniform movement for both of said pistons during movement of said pusher wall.

10. The combination of claim 7 wherein: said side walls at the upper rear end of said base frame include outer side plates; and said pusher means include outer side walls disposed immediately inside said outer side plates when said pusher wall is retracted.

11. The combination of claim 10 wherein: said pusher means include a top wall, said side and top walls of said pusher means being joined to top and side margins, respectively, of said pusher wall.

12. The combination of claim 11 wherein: said base frame has a lower front end wall extending up to a level above the level of the top of the opening in said lower rear end wall.

13. The combination of claim 1 and further comprising: probing plates, one of said plates being located at the front of each of said side walls, said plates being movable forwardly independently of said side walls to control collapse of trench walls ahead of said side walls.

14. The combination of claim 13 wherein: each of said probing plates overlaps a portion of the side wall at which it is mounted, both before and after forward movement of said plate.

15. The combination of clAim 14 and further comprising: plate drive means coupled to said plates; said pusher means including pusher drive means coupled to said pusher wall, and control means coupled to said plate drive means and to said pusher drive means to enable simultaneous powered forward movement of said plates and pusher wall with respect to said base frame, and simultaneous rearward movement of said plates and pusher wall with respect to said base frame.

16. The combination of claim 14 wherein: said pusher drive means include hydraulic actuators, and a source of hydraulic pressure therefor, and said plate drive means including hydraulic probing plate drive actuators, and a source of hydraulic pressure therefor; said control means include a first control valve having a first condition hydraulically locking said actuators for said pusher drive means, and having second and third positions for respectively extending and retracting said pusher wall; and said control means include additional control valves, each having a first position hydraulically locking the said probing plate drive actuator coupled thereto, and each having second and third positions for respectively power retracting and power extending the probing plate drive actuator coupled thereto, and each having a fourth position hydraulically neutralizing said probing plate drive actuator coupled thereto to permit the probing plate associated therewith to float in accord with external loads encountered thereby.

17. A trench shoring machine comprising: a base frame supportable on the bottom of a trench and having horizontally spaced upstanding side walls disposed to prevent collapse of the trench bank into the space between said walls; pusher means at the upper rear of said base frame and movable rearwardly and forwardly with respect to said base frame; probing plates at the front of said base frame immediately outside the outer faces of said side walls from a point near the bottom of said base frame to a point near the top of said base frame, said probing plates being movable forwardly and rearwardly with respect to said base frame.

18. The shoring machine of claim 17 wherein: said pusher means include pusher drive means; and plate drive means are connected to said plates.

19. The machine of claim 18 wherein: said pusher drive means include hydraulic actuators, and a source of hydraulic pressure therefor, and said plate drive means include hydraulic probing plate drive actuators, and a source of hydraulic pressure therefor; the machine further comprising control means including a first control valve having a first condition hydraulically locking said actuators for said pusher drive means, and having second and third positions for respectively extending and retracting said pusher means; and said control means including additional control valves, each having a first position hydraulically locking the said probing plate drive actuator coupled thereto, and each having second and third positions for respectively power retracting and power extending the probing plate drive actuator coupled thereto, and each having a fourth position hydraulically neutralizing said probing plate drive actuator coupled thereto to permit the probing plate associated therewith to float forwardly or rearwardly in accordance with external loads encountered thereby.

20. A method of shoring a trench including the steps of placing a shoring machine inside a trench, projecting separately movable probing plates forward from the sides of said shoring machine adjacent the trench banks in front of the machine; projecting a pusher wall from the rear of said machine against fill in the trench behind the machine and thereby moving the machine forward, and permitting the probing plates to remain in position with respect to the trench wall as the shoring machine is pushed forward by the pusher wall; and retracting the pusher wall and extending the probing plates forward again frOm the front of the machine as the machine remains at rest in the trench.