US3895680A

US3895680A - Fluid actuated hammer

Info

Publication number: US3895680A
Application number: US352556A
Authority: US
Inventors: Allen B Cook
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-12-28
Filing date: 1973-04-19
Publication date: 1975-07-22
Anticipated expiration: 1992-07-22

Abstract

A hollow central member is coupled to a tube to be driven into the ground. A driving mechanism includes a cylinder and piston surrounding the central member and a ram secured to the piston by a piston rod. The ram is reciprocated along the central member. A guide rod connected to the cylinder slides in a bore in the ram to prevent relative rotational movement between the cylinder and the ram. Air is delivered to the cylinder to raise and drive the ram downwardly. Means are provided for transferring the impact of the ram to the tube being driven.

Description

United States Patent 1191 Cook July 22, 1975 [54] FLUID ACTUATED HAMMER 3,583,501 6/1971 Aalund 173/78 X [76] Inventor: Allen B. Cook, 2121 W. 38th Ave.,

Vancouver, 3 C Przmary Exammer-Frank L. Abbott Assistant Exam'in'er-William F. Pate, Ill [22] Flled? 1973 Attorney, Agent,- '0r Firm-Seed, Berry, Vernon & 21' 1 Appl. NO.I 352,556 Bflynham Related U.S. Application Data [63] Continuation-impart of Ser. No. 212.957. Dec. 28. [57] I ABSTRACT 1971, abandoned. A hollow central member is coupled to a tube to be driven into the gr ound. A driving mechanism includes U.S- Cla cylinder surrounding the central memh r Cl. and a ram ecured to the piston a piston rod The 1 Fleld of Search ram is reciprocated along the central member. A 91/216 217 guide rod connected to the cylinder slides in a bore in 1 the ram to prevent relative rotational movement be- Referemes Clted tween the cylinder and the ram. Air is delivered to the UNITED STATES PATENTS cylinder to raise and drive the ram downwardly. 2.706,}03 4/1955 Stambaugh et al. 91/216 B ux Means are Provided for transferring the impact of the 2,988,158 6/1961 Baldwin 173/125 ram to the tube being driven- 3,524,5l 1 8 1970 K1 173 78 X 0 911970 sai v i 1. 1 73/72; 13 l 7 Drawmg Flgures FLUID ACTUATED HAMMER This application is a continuation-in-part of my US. patent application Ser. No. 212,957, filed Dec. 28, 1971, now abandoned.

FIELD OF THE INVENTION This invention relates to apparatus for driving openended tubes into the ground while simultaneously permitting the removal of materials from within the driven tube. Particularly, the invention pertains to fluidactuated devices for accomplishing this purpose.

DESCRIPTION OF THE PRIOR ART US. Pat. No. 3,474,870 discloses an apparatus for driving open tubes into the ground while allowing removal of materials from within the driven tube. The apparatus, although highly efficient, is quite bulky and difficult to maneuver and requires separate, independent guide rods for maintaining the ram on the driven tube.

SUMMARY OF THE INVENTION It is an object of this invention to provide an apparatus for driving an open tube into the ground while si multaneously allowing removal of debris from within the tube and wherein the apparatus is guided solely by a central member aligned with the driven tube.

It is another object of this invention to provide a tube driving apparatus of the type described above wherein a ram reciprocates on a central member and impact loads from the ram are delivered through various means which also align the central member with the tube being driven.

Basically, the invention accomplishes these objects by providing a hollow central member which supports a driving mechanism. The driving mechanism includes a piston and cylinder which surround the central tube. A piston rod is secured to the piston and, at its opposite end, is connected to a ram. Impact forces from the ram can be passed to the driven tube at either end of the hollow central member. One aligning means includes an internal shoulder on the central member, another includes a threaded connection, used particularly when pulling pipe out of the ground. Another aligning means includes a slip-on collar. Still another includes an internal conventional half-coupling. Air supply means controls the flow and direction of air to the cylinder so as to reciprocate the ram for imparting an impact to the driven tube.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevation with parts broken away for clarity of a driving apparatus embodying the principles of the invention.

FIGS. 2-4 are operational schematics. FIG. 2 illustrates the position of the ram at the moment of impact on the bottom of its stroke. FIG. 3 illustrates the ram being raised in preparation for the next stroke. FIG. 4 illustrates the position of the ram as it reaches the top of its stroke and begins to be propelled downwardly again.

FIG. 5 is an isometric of the hammer shown in FIG.

FIG. 6 is a fragmentary isometric with parts broken away for clarity illustrating a modified form of a hammer.

FIG. 7 is a longitudinal section of another embodiment showing in addition two styles of driven pipe connection, styles A and B.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As best shown in FIG. 1, the fluid-actuated hammer includes a cylindrical, hollow central member 10 having an upper flange 12 and a lower flange 14. The flanges are welded or otherwise sufficiently securely fastened to the central member to absorb impacts. An additional flange 13 is provided for driving the central member upwardly. A driving mechanism 16 is secured to the hollow central member and includes a ram 18. The ram is driven against the lower flange 14 or to suitable means to force the central member downwardly. The central member is also provided with means 20 for aligning the central member with the driven tube and suitable for transferring the impact from the central member to the tubing or casing T to be driven into the ground. An air supply means 21 delivers air in alternate directions to the cylinder to reciprocate the ram. The apparatus can be 'lifted and positioned over the tube to be driven by conventional hoisting apparatus secured to a pair of diametrically opposed ears 23.

The driving mechanism 16 includes a cylinder 22 surrounding the central member 10. The cylinder is provided with upper and

lower air passages

24 and 26, respectively. Between the central member and the cylinder is mounted a slidable piston 28 which is sealed against the outer surface of the central member and inner surface of the cylinder by suitable O-ring seals 30.

a The piston divides the interior of the cylinder into an upper chamber 32 and a lower chamber 34. Integrally formed on the piston 28 is a tubular piston rod 36. The ram is integrally formed on the opposite end of the piston rod. Suitable seals 38 seal the lower end of the cylinder around the piston rod 36. Seals 39 seal the upper end of the cylinder around the central member 10.

The surface area of the piston 28 exposed to the lower chamber 34 is less than the surface area of the piston exposed to the upper chamber 32. Thus air introduced simultaneously through the

passages

24 and 26 will produce a downward movement of the ram since greater force will be applied to the top of piston 28 than to the bottom.

The ram is provided with a longitudinal bore 40 which slidable receives a guide bar 42 that is secured to the cylinder 22. The guide bar prevents the ram from rotating relative to the cylinder 22.

The preferred embodiment illustrates a configuration best adapted for pulling the tube and for this purpose the tube T is provided with exterior threads 44. The aligning means 20 in this embodiment includes interior threads 46 in the lower terminal end of the hollow central member 10 which engage the threads 44. In soft soils this configuration can also be used for driving the tube T. The tubing member T is therefore recessed as at 48 to provide an abutment surface against which the lower end of the central member rests so that all of the impact is not taken solely by the

threads

44 and 46. In most applications the tubing T will be more adequately protected when being driven such as by the provisions of an'external collar similar to 20a (FIG. 6) or a conventional internal half-coupling, or the like.

The air supply means 21 includes an inlet pipe 50 coupled to an air conduit 52 which connects with the

passage

24 and 26. A valve 54 for delivering the air in various sequences includes an exhaust port 56, an intake port 58 and a valve block 60 positionable alternately to block the intake port 58 and interconnect passage 24 and exhaust port 56 or block exhaust port 56 and interconnect intake port 58 with air passage 24.

Movement of the valve 60 into the desired positions is I accomplished by a valve actuating mechanism 62.

The valve actuating mechanism 62 includes a rigid rod 64 secured to the ram 18. The rigid rod is provided with an upper cam 66 and a lower cam 68. Valve actuators 70 and 71 are rigidly secured to a shaft 72 that is secured to the valve block 60. The shaft 72 is mounted for oscillatory movement within the valve 54. As best shown in FIG. 5, the upper and lower cams are offset transversely on the rigid rod 64 and are aligned respectively with the valve actuators 70 and 71. Thus, upward movement of the ram will bring the lower cam 68- but rather the valve block will be rotated prior to that time so that the piston is decelerated and reverses direction prior to impacting. On the downward stroke it is generally desired that the ram impact the flange 14. On some occasions, however, when it is desired to drive the central member upwardly to remove the tube T from a hole, the positions of the cams are arranged to eliminate impact on the downward stroke.

To best illustrate the operation of the ram, reference is made to FIGS. 2 4. In FIG. 2 the ram is at the bottom of its downward stroke and has just impacted against the flange 14 moving the driven tube the distance equal to movement of the central member from the phantom line position as illustrated. Just at the moment of impact the upper cam 66 moves the valve actuator 71 downwardly to reposition the valve block 60 into the position shown in FIG. 3. Thus air is exhausted from chamber 32 and all of the incoming air is directed gage the flange 12 as shown in phantom lines in FIG.

The embodiment of FIG. 6 varies from the preferred embodiment in two important aspects. First, the hollow central member a is rigidly secured to the cylinder 22a, rather than being detachably secured thereto as in the preferred embodiment. In all other respects the driving mechanism and air supply are identical with the preferred embodiment. The second modified feature is in the means aligning the central member 10a and the driven tube or casing T. In this embodiment a separate collar body a is provided with anupper recess 101,

into chamber 34. The incoming air thus pushes against the underside of the piston 28 to raise the ram upwardly. Just prior to the piston reaching the top of the cylinder 22, the lower cam 68 engages the valve actuator 70 to reposition the valve block into the position shown in FIG. 4. In this position air enters both the chamber 32 and the chamber 34 cushioning the upward movement of the piston and again begins to propel the ram downwardly.

An important feature of this invention is the provision of a hollow central member through which a drill pipe 74 (shown only in FIG. 2 for brevity) or the like can be inserted to inject drilling fluid under pressure down through the driven tube. The fluid and freed mud is discharged through a discharge port 75.

As best shown in FIG. 1, the cylinder 22 can be positioned to drive the'central member 10 upwardly. In this position the

cams

66 and 68 are adjusted to cushion the downward impact of the ram 18 and to allow full impact in the upward direction. The .cylinder in this posia lower recess 102, and a pipe connector 100 for removing drilling mud from within the tube T. The central member and tube fit respectively in the recesses and abut against a central flange 102. In this embodiment the lower flange 14 is eliminated and the ram impacts directly against the collar body 20a. The surfaces between the recesses and the central member and tubing may be threaded if desired to allow the tubing to be moved upwardly as is the common practice. In operation the modified form of the apparatus is basically identical with that of the preferred form and further details are not believed necessary. As shown the collar body hasjust been impacted by the ram 18 and has slid its end rests on the central flange 103 prior to the next impact. v 7 Y The embodiment of FIG. 7 includes a hollow'c'entral member having an enlargement 82 at its lower end. A ram 84 impacts against the upper surface of' the enlargement. The upper end of the hollow central member is provided with an internal shoulder 86 that abuts against the upper surface of the tube 88 beingldriven into the ground. A piston 89 rides in a cylinder 90 that surrounds the hollow central member and is connected to the ram 84:by piston rods 91. The piston rods pass through bushings 92 provided in openings in the lower wall'of the cylinder. The cylinder, piston, and air-control valve 92 otherwise operate as in FIG. 1. j

-A urethane-ring 96- seals the lower end of the cylinder. A second urethane ring 97 seals the upper end of the cylinder in style A. In style A the cylinderis carried on a shoulder 9.8 on the outside of the hollow central -member. In style B a threaded connection 99 holds the cylinder on the hollow central member.

. Style A is used for driving casing down into the ground. Style B is for driving casing out of the ground but generally should not be used in view of the resulting severe impact loading on the cylinder and air control valve.

, While the preferred forms ofthe invention have been illustrated and described, variations and modifications thereof will be apparent to one skilled in the art. Accordingly,the invention is not to be limited to the preferred embodiments illustrated, but rather is to be limited only by a literal interpretation of the-claims ap-.

meansat the lower end of the central member for aligning said central member with the casing to be driven an'd adapted to be impacted by said ram axially of said centralrnember for downward movement, thus forcing the casing downwardly, and air supply means for delivering air to said cylinder in a prearranged sequence to propel the ram downwardly to drive the casing into the ground. '5 I 1 2. Apparatus of claim 1, said cylinder and central memberforming a chamber therebetween to receive the air, said piston having seals engaging both the cylinder and thecentral member and mounted for reciprocation in thechamber, said air supply means including means for deliveringair to either side of the piston in the chamber.

3. Apparatus for driving a casing and permitting the casing to be cleaned out while being driven, comprising a hollow central member having an axial opening therethrough, a driving mechanism surrounding said central member. said driving mechanism including a cylinder axially slidably mounted on said central member and a piston surrounding said central member, means for limiting said sliding movement, piston rod means secured to said piston, and ram means secured to said piston rod means for movement with said piston, means for locating the hollow central member with. said casing,

said driven casing, and air supply means for delivering air to said cylinder in a prearranged sequence to propel the ram axially to drive the casing axially.

4. The apparatus of claim 3, said impact receiving and transferring means including means on said hollow central member for engagement by said ram and means on said hollow central member for providing driving engagement with said driven casing.

5. The apparatus of claim 3, said means for transferring the impact to said driven casing including a horizontal surface engageable with a corresponding horizontal surface on the casing being driven.

6. Apparatus for driving a tube and permitting the tube to be cleaned out while being driven, comprising a hollow central member having an axial opening therethrough, a driving mechanism surrounding said central member, said driving mechanism including a cylinder and piston surrounding said central member, said cylinder being slidably mounted on said central member for limited axial movement, a piston rod secured at one end to said piston, and a ram secured to the opposite end of the piston rod, said driving mechanism including a longitudinal guide bar fixed against movement relative to said cylinder, said ram including a bore for slidably receiving said guide bar whereby the ram is precluded from moving around the central member relative to said cylinder, means at the lower end of the central member for aligning said central member with the tube to be driven and for receiving axial impact from said ram for forcing the tube downwardly, and air supply means for delivering air to said cylinder in a prearranged sequence to propel the ram downwardly to drive the tube into the ground.

7. Apparatus for driving a tube and permitting the tube to be cleaned out while being driven, comprising a' hollow central member. a driving mechanism surrounding said central member, said driving mechanism including a cylinder and piston surrounding said central member, a piston rod secured at one end to said piston. and a ram secured to the opposite end of the piston rod. means at the lower end of the central member for aligning said central member with the tube to be driven and adapted to be impacted by said ram for forcing the tube downwardly. and air supply means for delivering air to said cylinder in a prearranged sequence to propel the ram downwardly to drive the tube into the ground, said cylinder and central member forming a chamber therebetween to receive the air, said piston having seals engaging both the cylinder and the central member and mounted forreciprocation in the chainbehsaid air supply means in'cludingjmeans for delivering air to either side of the piston in. the chamber, said air supplying means further including a control rod having upper and lower cams, an air valve for directing air simultaneously into the top of said cylinder below said piston. or solely into the bottom of said cylinder, the crosssectional area of the piston being greater on its, top surface than on its bottom surface so that air delivered simultaneously to top and, bottom moves. the piston downwardly, actuator means engageable with said cams for positioningsaid air valve into'its various positions, said cams being so positioned that the valve is movedto an alternate position prior to;completio n of the piston upstroke so as to avoidundue-impact against the upperend of the cylinder. I i

8. Apparatus for driving a tube and permitting the tube to be cleaned out while beingdriven. comprising a hollow central member, a driving mechanism surrounding said central member, said driving mechanism including a cylinder and piston surrounding saidcentral member, a piston rod secured at one end to said piston, and a ram secured to the opposite end of the piston rod, means at the lower end of the central member for aligning said central member with the tube to be driven and adapted to be impacted by said ram for forcing the tube downwardly, and air supply means for delivering air to said cylinder in a prearranged sequence to propel the ram downwardly to drive the tube into the ground, said impacting and aligning means including a collar body having an upper surface for receiving the impact of said ram, an upper bore for receiving said central member, and a lower bore for receiving said driven tube, and means abutting the ends of the tube and central member for transferring the impact to the driven tube.

9. Apparatus for driving a tube and permitting the tube to be cleaned out while being driven, comprising a hollow central member, a driving mechanism surrounding said central member, said driving mechanism including a cylinder and piston surrounding said central member, a piston rod secured at one end to said piston, and a ram secured to the opposite end of the piston rod, means at the lower end of the central member for aligning said central member with the tube to be driven and adapted to be impacted by said ram for forcing the tube downwardly, and air supply means for delivering air to said cylinder in a prearranged sequence to propel the ram downwardly to drive the tube into the ground, said impacting and aligning means including interior threads on said central member, exterior threads on said driven tube and a recess on the end of said tube in engagement with said central member for receiving impact therefrom, said central member including a rigid impact of said ram.

10. The apparatus of claim"7,fsaid driving mechanism I including a longitudinal'guide bar 'fix'edagainst movement relative to said cylinder. said ram including a bore for slidably receiving said guide barwhereby the ram is precluded from moving around the central member relative to said cylinder".

11. Apparatus for driving a tube and permitting the tube to be cleaned out while being driven, comprising a hollow central member,. a driving-mechanism surrounding said central member, said driving mechanism including a cylinder and piston surrounding said central member, piston rod means secured to said piston, and ram means secured to said piston rod means for movement with said piston, means for locating the hollow central memberl with said tube in proper alignment for driving the tube, means for receiving impact blows from saidramfor transferring 'the impact to said driven tube; and air supply means for delivering air to said cylinder in a prearranged sequence'tto propel the ram downwardly to drive the tube into the ground, said impact receiving and transferring means including a rigid flange fixedaon the lower end of the central member and said 'loca'ting-rneans including threads interconnecting the-hollo'w central member with-said driven tubel: i

ml'Z. Apparatus for driving a tube and permitting the driving the tube. means for receiving impact 'blows from-said ram for transferring the impact to said driven tube to be cleaned out while beingidriven, comprising a hollow central member, a driving mechanism surrounding said central member, said driving mechanism including a cylinder and piston surrounding said central member, piston rod means secured to said piston, and ram means secured tosaid piston rod means for movement with said piston, means. for locating the hollow central member with said tube in proper alignment for driving the tube, means for receiving impact blows from said ramfor transferring the impact to said driven tube, and air supply means for delivering air to said cylinder in a prearranged sequence to propel the ram downwardly to drive the tube into the ground, said impact receiving and transferring means including means on said hollow central member for engagement by said ram and means on said hollow central member for providing driving engagement with said driven tube, said ram engaged meansincluding an enlargement formed on the lower end of said-central member, said means for providing driving engagement-with said-driven tube includingan internal abutment on the upper end of said hollow central member. Tl

Claims

1. Apparatus for driving a casing and permitting the casing to be cleaned out while being driven, comprising a hollow central member having a straight, large axial opening adapted for receiving rods or the like, a driving mechanism surrounding said central member, said driving mechanism including a cylinder axially slidably mounted on said central member and a piston surrounding said central member, means on said central member for limiting said sliding movement of said cylinder, a piston rod secured at one end to said piston, and a ram secured to the opposite end of the piston rod, means at the lower end of the central member for aligning said central member with the casing to be driven and adapted to be impacted by said ram axially of said central member for downward movement, thus forcing the casing downwardly, and air supply means for delivering air to said cylinder in a prearranged sequence to propel the ram downwardly to drive the casing into the ground.

2. Apparatus of claim 1, said cylinder and central member forming a chamber therebetween to receive the air, said piston having seals engaging both the cylinder and the central member and mounted for reciprocation in the chamber, said air supply means including means for delivering air to either side of the piston in the chamber.

3. Apparatus for driving a casing and permitting the casing to be cleaned out while being driven, comprising a hollow central member having an axial opening therethrough, a driving mechanism surrounding said central member, said driving mechanism including a cylinder axially slidably mounted on said central member and a piston surrounding said central member, means for limiting said sliding movement, piston rod means secured to said piston, and ram means secured to said piston rod means for movement with said piston, means for locating the hollow central meMber with said casing, means for receiving impact blows from said ram axially of said central member for transferring axial impact to said driven casing, and air supply means for delivering air to said cylinder in a prearranged sequence to propel the ram axially to drive the casing axially.

7. Apparatus for driving a tube and permitting the tube to be cleaned out while being driven, comprising a hollow central member, a driving mechanism surrounding said central member, said driving mechanism including a cylinder and piston surrounding said central member, a piston rod secured at one end to said piston, and a ram secured to the opposite end of the piston rod, means at the lower end of the central member for aligning said central member with the tube to be driven and adapted to be impacted by said ram for forcing the tube downwardly, and air supply means for delivering air to said cylinder in a prearranged sequence to propel the ram downwardly to drive the tube into the ground, said cylinder and central member forming a chamber therebetween to receive the air, said piston having seals engaging both the cylinder and the central member and mounted for reciprocation in the chamber, said air supply means including means for delivering air to either side of the piston in the chamber, said air supplying means further including a control rod having upper and lower cams, an air valve for directing air simultaneously into the top of said cylinder below said piston, or solely into the bottom of said cylinder, the cross-sectional area of the piston being greater on its top surface than on its bottom surface so that air delivered simultaneously to top and bottom moves the piston downwardly, actuator means engageable with said cams for positioning said air valve into its various positions, said cams being so positioned that the valve is moved to an alternate position prior to completion of the piston upstroke so as to avoid undue impact against the upper end of the cylinder.

8. Apparatus for driving a tube and permitting the tube to be cleaned out while being driven, comprising a hollow central member, a driving mechanism surrounding said central member, said driving mechanism including a cylinder and piston surrounding said central member, a piston rod secured at one end to said piston, and a ram secured to the opposite end of the piston rod, means at the lower end of the central member for aligning said central member with the tube to be driven And adapted to be impacted by said ram for forcing the tube downwardly, and air supply means for delivering air to said cylinder in a prearranged sequence to propel the ram downwardly to drive the tube into the ground, said impacting and aligning means including a collar body having an upper surface for receiving the impact of said ram, an upper bore for receiving said central member, and a lower bore for receiving said driven tube, and means abutting the ends of the tube and central member for transferring the impact to the driven tube.

9. Apparatus for driving a tube and permitting the tube to be cleaned out while being driven, comprising a hollow central member, a driving mechanism surrounding said central member, said driving mechanism including a cylinder and piston surrounding said central member, a piston rod secured at one end to said piston, and a ram secured to the opposite end of the piston rod, means at the lower end of the central member for aligning said central member with the tube to be driven and adapted to be impacted by said ram for forcing the tube downwardly, and air supply means for delivering air to said cylinder in a prearranged sequence to propel the ram downwardly to drive the tube into the ground, said impacting and aligning means including interior threads on said central member, exterior threads on said driven tube and a recess on the end of said tube in engagement with said central member for receiving impact therefrom, said central member including a rigid flange adjacent the lower end thereof for receiving the impact of said ram.

10. The apparatus of claim 7, said driving mechanism including a longitudinal guide bar fixed against movement relative to said cylinder, said ram including a bore for slidably receiving said guide bar whereby the ram is precluded from moving around the central member relative to said cylinder.

11. Apparatus for driving a tube and permitting the tube to be cleaned out while being driven, comprising a hollow central member, a driving mechanism surrounding said central member, said driving mechanism including a cylinder and piston surrounding said central member, piston rod means secured to said piston, and ram means secured to said piston rod means for movement with said piston, means for locating the hollow central member with said tube in proper alignment for driving the tube, means for receiving impact blows from said ram for transferring the impact to said driven tube, and air supply means for delivering air to said cylinder in a prearranged sequence to propel the ram downwardly to drive the tube into the ground, said impact receiving and transferring means including a rigid flange fixed on the lower end of the central member and said locating means including threads interconnecting the hollow central member with said driven tube.

12. Apparatus for driving a tube and permitting the tube to be cleaned out while being driven, comprising a hollow central member, a driving mechanism surrounding said central member, said driving mechanism including a cylinder and piston surrounding said central member, piston rod means secured to said piston, and ram means secured to said piston rod means for movement with said piston, means for locating the hollow central member with said tube in proper alignment for driving the tube, means for receiving impact blows from said ram for transferring the impact to said driven tube, and air supply means for delivering air to said cylinder in a prearranged sequence to propel the ram downwardly to drive the tube into the ground, said locating means including a collar body having an upper bore for receiving said central member and a lower bore for receiving said driven tube, said impact receiving and transferring means including means on said collar abutting the ends of the driven tube and the central member for transferring impact to the driven tube.

13. Apparatus for driving a tube and permitting the tube to be cleaned out while being driven, comprising a hollow central member, a drIving mechanism surrounding said central member, said driving mechanism including a cylinder and piston surrounding said central member, piston rod means secured to said piston, and ram means secured to said piston rod means for movement with said piston, means for locating the hollow central member with said tube in proper alignment for driving the tube, means for receiving impact blows from said ram for transferring the impact to said driven tube, and air supply means for delivering air to said cylinder in a prearranged sequence to propel the ram downwardly to drive the tube into the ground, said impact receiving and transferring means including means on said hollow central member for engagement by said ram and means on said hollow central member for providing driving engagement with said driven tube, said ram engaged means including an enlargement formed on the lower end of said central member, said means for providing driving engagement with said driven tube including an internal abutment on the upper end of said hollow central member.