IE39687B1 - Improvements in pile driver - Google Patents

Abstract

An airgun repeater powered pile driver embodying the present invention is capable of driving piles of various types and sizes including immense piles to be driven down into the earth and can be operated totally submerged, partially submerged or entirely in the air. A first driving impulse down upon the pile commences when the airgun repeater is fired into a discharge chamber and continues for a relatively long time interval while the discharge chamber wall of great strength remains effectively telescoped within a closely surrounding sleeve as the massive weight above the airgun moves upwardly. Thereafter, the released high pressure gas intermixed with water can escape upwardly between the rim of the discharge chamber wall and the surrounding sleeve. A second driving thrust is provided when the rim of the discharge wall impacts down with respect to a driving head at the bottom of the surrounding sleeve. The pile driver can also be operated within the bore of very large diameter piles. [US3817335A]

Description

39687 This invention relates to ;» pil« driver of tb>. tyoc which in powered, i.e. in <*hich the pile driving thru^t.'i ••re generated, by the <>brupt discharge of <■ charge of prHM.MUi-i.zed gt*s which occurs upon (•ctu^-tion of * pressurized gac discbarge epparutus. Cuch apparatus is known in the irt - The airgun ia loaded or energised with high nreosure gas, which is usuolly coupreseed sir. However, other pressurized guses, utesa under pressure, or pressurised vapor, c; n be ear>loyed. Accordingly, i>s used in this specification and the appended claias, the term "pressurized gas" or "high pressure gas" is intended to be construed broadly to include compressed air, steam, gaseous products of coabustion, or other pressurized gas or vapor.

It is an object of the invention to provide a pile driver of the above type which is h technological advance in the ^.rt with r*cr>ect to pile drivers j-u disclosed in United States Pi'tentc Kos: ?,604,519 ;md 3,646,593.

According to the prusent invention, there is proviaci pile driver of the type in which, in operation, pile driving thrusts result froa the abrupt discharge of charge: of a pressurised gas by a pressurised gas discharge t-ppnr.-itus, the pile driver including ua elongate weight, a tubular w: 11 connected to the lower end of the weight, the wall extending downwardly from the weight, having :> lower rim, and deli nine, a discharge chamber dupted to receive and mount " pressurised g**r. discharge ;>ppt wall in clos<: telescoping relationship to essentially close the discharge chambcr, to a second position, in which the discharge chamber is vented, when u charge of pressurised gao in discharged in the discharge chamber, to generi It is to be understood that the positional terms, such as "upper", "lower" and "downwardly", ua used in th'-; specification and the appended dims arc related to tho i.ormul gener-lly upright operating position of the nile driver.

The airgun-powered pile uriver embodying the prt-s>;r.* invention is. ct»pable of driving piles ol various type.-: ana si/.cs, including, immense piles to be ariven down ii:to tne earth, -nd can be operated totally submerged, partiall. suboor,;ed or entirely in the air. A lirct ariving impuls».-dowa upon the pile commences when the airgun is firea into the discharge chamber and continues for - relatively long time peried while the discharge chamber wall, which i;j ol great strength, remains effectively telescoped withir. tu< closely surrounding sleeve as the massive weight above th' :irgun moves upwardly. Thereafter, the released high pressure gas intermixed with water can escape upwardly between the rim of the discharge cnamber w;.ll and the surrounding sleeve. A seconu driving thrust is providec wh« 39687 the rim ol the ditiCh. rge chamber w:• 11 impiety dovn with respect to »» driving hei-d at the bottom of the surrounuint. sleeve.

The pile driver can also be operated to udvant^be within the bore of very large diaaeter piles.

In order that the invention may be aore readily understood, various eabodiaents thereof will now be described with reference to the accompanying drawing*,in which Figure 1 is a longitudinal, sectional view of n tirgon-powered pile driver embodying the present invention, and particularly tdi-pted for operation underwater, lthoutn the embodiment of Figure 1 can nlr.o be used to udvunt-^/? in the • ir: i'it.ur«.* ia . u enlarged t;ect. iour-1 vi<»w of the lower portion oi' th»> oile oriver ol figure 1 showing the airt.ut! ;»rd me Coive weight in their first or re- r position; Figure 3 iy ^ cross-aection;il view t. ken through the plane 3-? in Figure Figure 4 is ■- cross-section 1 view t.-cun through the plane 4-4 in Figure 2; Figure p is a view similar to Figur* ■>'!o chowi.-i^ th»- i.il's ariver operation with tn«r argur. m-n missive weitnt iii th^ir r.ecnu or r;>i:,..:i -lo^ition .:u r the ..iiisu: hiis been ".irec" in c cycle of operation; Fij^uxv 6 is '.nother view similar to Figur* 5» the drgun .-md massive weight return towards their first or rest position, approaching the end of cycle of operation; Figure ? is a;: enlarged lont.ituuiix.l, section;.! vn w 39687 of the upper portion of the pile driver of 7igure 1; Kigur«: 6 is a view similar to Figure 7 showing the raised position of the aassive weight after the airgun has been "fired* in a cycle of operation; Figure 9 is a longitudinal, sectional view taken through the plane 9-9 of Tlgure 7 shoving the manifold and flexible hoses in further detail; Figure 10 Is a longitudinal, sectional view similar to Figure 7 showing a ratified embodiment of the Invention in which the flexible host lines are replaced by a sliding seal telescoping manifold; Figure 11 is e longitudinal, sectional view of the upper portion of a aodified embodiment of the present invention which is particularly adapted for operation in the air; and Figure 12 illustrates the pile driver of Figure 1 being used underwater to drxve a long hollow pipe pile in the interior thereof near the center of the pile itself for driving the pile into the earth beneath a body of water.

Referring to the embodiment of Figurea 1 and 2 in greater detail, the airgun-powered pile driver 10 includes a massive elongate cylindrical weight 12 which is movable up and down within an elongate cylindrical housing 14< for driving a pile 15, only the upper end of which is shown in Figure 1. Secured to the lower end of the massive weight 12 is a pressurised gas discharge apparatus comprising an airgun 16. This oirgun 16 may advantageously be such as ic described in U.S. Patents Kos: 3,310,128 and 3,379,273. The airgun may be repetitively actuated (hereinafter called "fired"). Each time the airgun is fired, it abruptly 3968? releases a charge of very high pressure gas, e.g. coapressed air. This pressurized gas is supplied throueh .. high pressure line 18 from a suitable source, such as u multiple stage air compressor 20(us illustrated in Figure 11) connected to a storuge tank 22, associated with a filter and shut off »nd bleed valves generally indicated at 2*.

At- described in said U.S. patents, l'uel Bay be mixou with a charge of compressed sir in the airgun 16 and burned in it for further raising the pressure therein before the abrupt discharge of high pressure gas, which occurs each time it is fired. When the airgun 16 is firod, the pressurized gas is abruptly discharged, as shown by the arrows 25 in Figure 5, through a plurality of ports 26 (only one is seen in Figures 1, 2 and 5).

During operation of the pile driver, the airgun 16 is typically charged with coapressed air at high pressures, for ex>>aple, in the range froa 1,000 to 3,000 pounds per square inch; however, higher or.lower pressures Bay be useu. The t-ctual pressure employed to operate the airgun depenus upon its size, the size of the massive weight 12, the size of the pile, and the characteristics of the earth aaterial into which the pile is being driven, and this pressure provides s convenient parameter for control of the pile driving operation.

Secured to the lower end of the massive weight 12 is a cylindrical wall 28 which completely encircles the airgun 16 ana defines a discharge chamber 30 having an open mouth 32 facing downwardly. The cylindrical wall 28 extenos down below the lower end of the airgun. This cylindrical wall 28 is fonned of strong materinl because it uervos number of functions as will be explained further below. 39687 In order to -secure the strong cylindrical wall 28 to the. lower end or the msssive weight 12, there is an annular recess 34 foraed near the lower end of the weight 12 d.' fining a flange 36. A plurality of attachment bolts 38 (Figure 4) pass through holes in this flange 36 and are screwed into the top of the wull 28.

For holding the airgun 16, there is a mounting ring 40 which surrounds the upper end of the airgun, with a plurality of bolts 42 screwed through this ring into the lower end of themassive weight 12. Vithin the south 32 of the cylindrical chamber wall 28, there are a plurality of radial strut8 or vanes 44 (Figure 3) connected to a centrally located retainer socket element 46. This retainer socket element 46 h^s a wall 48 therein for holding the lower end of the airgun 16. Shock absorbing pud means 50 of resilient arterial, for example of polyurethane, rubber or other shock absorbing resilient material, i-re seated in the socket element 48 beneath the lower end of the uirgun. If desired, eimilar shock absorbing means (not shown ) may be located within the mounting ring 40 between the upper end of the airgun 16 and the lnxor "iKi of the cylindrical weight 12.

Oporatively associated with the airgun 16 and tho cylindrical chamber Kail 26 is a movable impulse-transmittir.g member %; including driving he;jd 54 with un upstanding cylindrical sleeve 36. This sleeve 36 closely surrounds the outer surface of the cylindrical chamber wall 28. The inner surface of the cylindrical sleeve 36 includes a cylindrical zone 135 (Fieure 5) adjacent its lower end, and within the upper <}nd portion 58 of the sleeve, a conical / 3 8 6 8 7 aone l/) which pmgi-eaoively recedes in an upward directi-vj from the outside surface of the w.-.ll 28.

The impulse transmitting member 52 h< a a circuta-ferentiul groove 60 adapted to be connected by a ring clasp 62 aecured by clasp bolts 63 to a groove 64 in a detachable pile driving adapter 66 which engages the pile 15 being driven. The pile 15 is shown as a large pipe pile being driven underwater.

In Figure 1, the pile 15 end the entire pile driver 10 are assumed to be submerged underwater (not shown) with the pile driver being suspended froa the top by & chain sling 68 supported from a large crane (not shown) on a barge or ship.

Although a pile pile 15 is shown, it is to be understood thi-t thiu is illustrative «nd thut the pile driver 10 can be used to drive any type or drivable pile, such as nn H-beaa pile cv a timber pile. Moreover,in addition to being capable ol" driving piles Iron their upper ends, attention is invited to Figure 12, which shows th't the pile driver 10 embodying the present invention can be used to drive hollow piles by being placed in the interior of such piles. When it is desireu to drive .. different size of pile or a different type of pile, thee the ring clamp 6L* in temporarily disconnected and t different ad- pt-66 is inserted for providing the desired coupling to the pile to be driven.

In order to control the firing of the Hirguii 16, there iu un electrical firing control cable 70 connected to a solenoid operated valve 72 mounted on the airgun. By transmitting an electrical signal through the cable 70, 39687 the valve 72 is actuated to i'ire the airgun 16, as will be understood by reviewing vhe two U.S. patents discussed above. In this wuy the pile driver 10 can be remotely controlled to produce cycles of operation which are repeated ut frequent intervals, aj may be desired toy the user, for example, approximately every two seconds.

Alternatively, the pile driver 10 can be arranged to be self-operating. This is accomplished by replacing the solenoid operated valve 72 by a pressure-responsive release valve which is set at a predetermined release pressure as desired by the user. Thus, the airgun 16 becomes self-firing. As soon as the pressure of the pressurised gas therein has reached this pre-set release pressure, the airgun fires. An advantage of making the airgun self-firing is that the control cable 70 and associated connections con be omitted. The repetition rate of thn cycles of operation when the airgun is self-firing is controlled by the user by controlling the rate at which pressurized gus is fed through the high pressure li&el8 into the airgun. The faster this gas is supplied to the airgun, the sooner it will fire, and the more frequent will be the cycles of pile driver operation, and vice versa.

The massive weight 12 is provided with an axial through-bore 74 for accommodating the firing control cable 70 and the high pressure airline 18. The airgun 16 is located adjacent to the lower end of the bore 74 for connection to the electrical cable and to the high pressure supply line 18.

The discharge chamber 30 is normally filled with water prior to tho firing of the airgun 16. To supply water 39687 to thiii chamber for maintaining the uir^ii uubmerg^d durini; operation, f* continuous flow of *:>ter io pusned down through the r.xi.-l yv-asuge 74. To feed thi:. liquid iron poBSiige 74 into the chambcr 30, there ore Tour ridi:ii distribution passages ?6 (pieuse also Bee Figure 4) which brunch off froa the axial passage 74 ne>-r th* l^. cr end of the weight 12. These radial passages 76 coaaunic; te with Tour vertical passages 78 feeding down into the top ol' the discharge chamber 30 around the airgun 16. Thus, water i:. continuously fed down into the dir.ch.- In order to feed w< Aa shown aoat clearly in figures 7, 8 and 9 on the side of the upper end of the standpipe 80, there is a water manifold box 100. This manifold 100 has a plurality of elbow pipe connections 102. A plurality of flexible water hoses 10* are attached by connections 106 to the multiple pipe connectiona 102. Bach hose line 1W haa a alack loop, und the hoae lines are positioned in aide-by-side relationship, being connected at their upper ende by connectors 108 attached to a second stationary water aanifold 110. A large diaaeter water supply hose 112 feeds into this stationary aanifold 110, and a puap (not shown) serves to feed water through the hose 112.

The reason for utilizing the multiple hoses 10* in side-by-side relationship is to provide the desired delivery capacity for the water while at the same time providing a high decree of flexibility and clearance within the cylindrical housing 14 to accomodate up and down motion of the standpipe 80 which occurs during each driving cycle.

To provide for servicing of the components, namely, the electrical,water und high pressure gas supply lines, fittings, and connectors in the upper end of the pile driver housing 14, there is a removable sleeve 114 which closely fits into the housing 14 und is removably secured in position by a plurality of attachment screws 116. When it is desired to service these components, the screws 116 are 30687 removed ;»nd tho sleeve T)4 is pulled up out of the housing 14 to expose such components* lbs chain sling 68 is connected to a pair of eyes welded to heavy steel pads 120 ou opposite sides of the pile driver detachable secured by piltiple screws 116 to both the slews 11* and to ths housing 14. la the water flows down through the central passages 7* and branch passages 76 and 78, this flow pushes a cheek valve member 122 down against an annular stop 124 on the mounting ring 40. Thus, the water has free access, as seen most clearly in Figure 2, to enter into the discharge chamber 30. The check valve member 122 is in the form of a ring which oncircles the mounting ring 40. An annular channel 126 interconnects the lower ends of the vertical passages 78 to facilitate entering flow of the water into the discharge chamber.

When the airgun 16 is fired, the sudden surge of pressure in ths discharge chamber 30 pushes the check vulve member 122 up to block momentarily the channel 126 and to block pussage3 78. Thus, the abrupt pressure rise in the chamber 30 is confined and is directed downwardly through the open mouth 32.

The operation of the pile driver 10 will be explained in further detail: Vhen the pile driver members are sitting in their first or normal rest position ( as shown in Figures 1, 2, 7 and 9) immediately before firinc of the airgun 16, water fills the chamber 30, and the lower rim 128 of the cylindrical wall 28 is seated down in un annular groove 130 in the driving head 5*. In this initial position, the wall 28 is closely telescoped within the 39687 surrounding sloeve 56 while the rim 128 seats down in the groove 130 to provide an essentially closed discharge chamber 30 in which the water is confined by ths rigid vail 28. This water in the discharge chamber is confined below the lower end of the weight 12 and above the driving head 5** The air gun 16 say be electrically fired or say be self-firing, us discussed in detail above. Immediately after ths airgun h&s been fired, high pressure gas is abruptly released through the ports 26 into the discharge chamber 30 producing u sudden or violent increase of pressure in this chamber. Shis sudden surge of pressure thrusts down against the top surface 132 of the driving head 5*» and also pushes up against the check valve member 122 and against the lower end of the weight 12.

As shown in Figure 5, «n immense thrust is delivered downwardly onto the driving head 5*. At the s*ne time, un upward driving force is delivered up against the massive weight 12 causing this weight to Jump upwardly, as illustrated in Figure 5.

The advantageous telescoping relationship between the cylindrical wo 11 28 and the closely surrounding cylindrical sleeve 36 maintains the confined relationship of the wuter and of the released high pressure gas in the region 136 above the driving head 3*. This confined relationship is continued until such time as the rim 128 has raised above the line of demarkation 134 between the cylindrical zone 135 of the inner aurface of the aleeve 56 and the outwardly eloping generally conical zone 59. This confinement by these telescoping parts produces a protracted downward thrust upon the driving head 5*. - 13 - In effect, the region 136 within the cylindrical zone 135 forms en extension of the discharge chamber 30 thereby providing an expandable chamber which confinea the released pressurised gas and water therein for 0 significant interval of time after the pressurized go3 is initially released into the chamber 30. The arrows 139 (Figure 5) illustrate ths downward flow of the released pressurised gas and water from the chamber 30 into the extension chamber 136.

As shown in Figure 5, after the rim 128 has moved above ths line of demarcation 134, the intense pressure within the combined extended chamber 30-136 drives the water and air (or other pressurised gas) upwardly, as indicated by the elongated flow arrows 137. This expulsive flow 137 is very rapid, as indicated by the length of the arrows 137» for it occurs through the clearance space 138 between the rim 128 and the sloping sone 59. Initially, this clearance apace Is small and so the initial expulaive flow 137 is of high velocity. As the wall 28 of the dischargechamber continues to move upwardly, the clearance space 138 progressively enlarges, the pressure in the chamber 40-136 falls, and so the expulsive flow 137 diminishes in velocity.

The force of gravity slowa the upward motion of the massive weight 12 and causes it to fall back downwardly toward its initial position. As shown in Figure 6, when the rim 128 of the cylindrical chamber wall 28 falls b.~ck down into the shock-damping groove 130, a second powerful driving impulse is delivered to the driving head 5* for thrusting the pile downwardly into the earth. As shown in - 14 - 3068? Figure 6, the water which remained trapped In the groove 130 produces ^ dushpot shock-daaping action because ths inner wall 140 of this groove 150 slopes inwardly progressively restricting ths upward flow 141 of the trapped water as the ria 128 enters thid groove.

Thus, in summary, it will be understood that two powerful driving thrusts are delivered during each cjcle of operation of the pile driver 10. The first of thess driving iapulses is longer in duration than the second one. The first driving iapulse occurs during the time interval after discharge of ths pressurised gas froa the uirgun 16 into ths discharge chamber 30. This first driving iapulse continues until after the ria 128 has passed above the transition line 154, thus releasing the expulsive i'lo* 137* The second driving iapulse occurs when the lower edge or ria 128 ol* the wall 28 strikes down into the shock-damping groove 130. By virtue of the fact that water has been expelled along with the released gus, us indicated in Figure 5 by the arrows 137* the aassive weight 12 falls back down relatively quickly under the pull of gravity to deliver the second powerful driving thrust. Figure 6 illustrates occurrence of this second driving thrust upon iapact of the wall 28 down into the shock-damping groove 150. The chamber wall 28 ia aade very strong to withstand the sudden surge of pressure occurring upon discharge of the airgun 16. It i3 also strong to withstand the compressive stress occurring when the ria 128 impacts down into the shock-damping groove 130. It is possible to oait the groove 150, thus causing the ria 128 to strike upon the top surface of ths driving h«.ud 54 if such an impact driving action is desired. It is preferable, in our opinion, to include the shock-daaping groove 150 to increase the operating life of the various parts. - 15 - 39687 II the pile is being driven into softer soil or sedimentary materiel, * larr.er downward notion of the driving he;id 54 occurs during the first driving thrust; whereas, if the pile is being driven into h. rder soil or 5 sore resistant strata, then the downward notion of the driving head 5* i® lesser during this first driving thrust.

Accordingly, when the pile is being drives into such harder aaterial, the weight 12 tends to juap higher and 10 consequently an increased force tends to occur daring the second driving thrust, because the veight 12 has fallen froa u somewhat greater height in the housing 14.

There »re a plurality of vertically elongated guide shoes 142 and 144 at spaced positions around ths lower 15 and upper ends, respectively, of the aassive weight 12.

Tor example, there ure six each of these guide shoes 142 and 144. Their lower und upper ends are tapered as indicated nt 145. The outer surfaces of these shoes 142 and 144 are covered with wear^resistant runners 146 (Figure 2) 01 20 bearing aaterial. For example, when the cylindrical housing 14 is made of steel, the wear-resistant runners 146 are made of bronze bearing aaterial. Thus, these runners 146 cbsorb most of the wearing action, and they are removed and replaced on the shoes 142 and 144 when they becoae 25 worn out.

Alternatively, the runners 146 can be Bade of extreaely hard wear-resistant aaterial. In thiu latter conn, the housing 14 absorbs aost of the wear and is replaced whui: it becomes worn out. 30 As shown in Figure 8, the slack loops in the lines - 16 - 38887 18A, 70A and multiple lines 104 accomodate the upward movement of the standpipe 80 which occurs during each cycle of operation of the pile driver.

In the modified pile driver 10A shown in Figure 10, 5 the sleek flexible lines and hoses 18A, 70A and 104 und associated components are replaced by an end portion OQA of the standpipe 80 which extends into a stationary cylindrical manifold 110A. This manifold 11QA is held in place by a plurality of radial struts 130 and 152. The 10 lower and upper struts 150 and 152, respectively, are attached us by welding to the removable sleeve 114. A seal ring 154 la mounted in watertight relationship in the lower end of the manifold 110A and has a sealing element 156 surrounding and engaging the standpipe 30-80A in 13 sliding relationship. A second seal ring 158 is mounted in watertight relationship in the upper end of the manifold 11 OA with a sealing element 160 slidingly engaging the standpipe 80-80A.

Vater is fed into the manifold 110A from the large 20 diameter hose 112. A plurality of porte 162 drilled in the standpipe extension 80A permit the water to flow from the annular chamber 164 within the stationary manifold 110A into the standpipe 80-80 A.

The length of the stationary manifold 11 OA between 25 the first and second sealing rings 154 and 138 is sufficient to enable full travel of the movable standpipe 80-80A to occur without permitting the ports 162 to move outside of the chamber 164. The end cap 86 seals tho upper end of the standpipe extension 80A. 50 In Figure 11, there is shown a third embodiment ol' pile - 17 - 39687 driver 10B in which an enclosure 170 is connected to the top ol* the housing 14. This pile -.iriver 10B ij particularly adapted for driving operations curried out in the air, although it is possible to use this pile driver 5 partially or completely under water.

The enclosure 170 serves to catch the water which is expelled up through the clearance space arouml the massive weight 12 (i.e. the clearance space 138 in Figure 5)« The water which is caught travels out from the enclosure 170 10 through a large flexible hose line 17* extending to a water—-lr separator 176 positioned remotely from the til* driver 10B. The nose line 17* has sufficient diameter for the air and water to rush out from th-i enclosure 1?0. After the mater hi.s been separated from the air, the air 15 is disch rged back into the atmosphere through un outlet 178, while the water feeds through ; lint 180 exten.-iiiK to reservoir 182. A pump 184 connected to the ronorvnir feeuj; the <.ater through the- hose line 11c bick to the pile driver. c'O It is tr> be understood th-.t t-he 'M-closure 170 be used kith either the embodiment of the rile uriver 10, ahown in I-'iture 7, or the modified pile driver 10^, r.ho.n n. Figure* 10. The enclosure 170 has sufficient headroom to permit the full extent of upward travel of the standpipe 80 25 to occur without interference.

Figure 12 shews the pile driver 10 or 10A beint ur.ed to drive a long hollo* pipe nile 15. The adapter 66a connected to the lower end of the pile driver his un outwardly extending flange 186 which engaj.es aovi nil® 1^. It ir. - 18 - 30687 to be appreciated that the pile 15 being driven may hiivo < Inviting attention back to Figure 2, there are a plurality of relatively small passages 190 communicating with the top end of the discharge chamber 30. These passages perait the in-flow of water entering chamber 30 from passages 78 to purge out uny air (or other gas) remaining in the chamber 30 after the weight 12 has dropped down to its initial position. After the purging has occurred so that the chamber 30 is again substantially full of water to submerge the airgun 16, the cycle is ready to be repeated by again firing the airgun. These passages 190 are relatively small ao that they do not permit the escape from chamber 50 of much of the pressurized gas released therein by the airgun.

The movable impulse transmitting member 52 is retained in the lower end of the housing 14 by a flange 192 which is - 19 - 39687 positioned above a atop shoulder 19^ secured in the lov.er end of the housing* The multiple vent holes 196 allow oscw.no of water froa between the flange 192 -nd the atop shoulder 19* when the member 52 is being driven down. 5 The various embodiments of the pile drivers of the present invention are particularly well adopted for driving enormous piles into the eorth, either totally submerged or partially submerged or on land.

The massive weight 12 may, for examplo, lie in the 10 range from 10,000 lbs. up to a quarter of a million pounds. The airgun 16 Bay* for example, have a chamber volume frost 300 cubic inches up to 10 cubic feet.

In the illustrative embodiment of Figure 1, the weight 12 is of steel having a length of 20 feet and a diameter of 15 2 feet and weighs in the order of approximately 28,000 pounds. The cylindrical chamber wall 28 is of solid steel four inches thick and has an inside diameter of approximately 1* inches. The ;-irgun 16 has a volume of 1,000 to 2,000 cubic inches. - 20 - 38087

Claims (18)

CLAIMS i-

1. A pile driver of the type in which, in operation, pile driving thrusts result froa the abrupt discharge of charges of a pressurised gas by a pressurised gas discharge apparatus, ths pils driver including an elongate weight, .a tubular wall connected to ths lower end of the weight, the wall extending downwardly from the weight, having a lower ria, and defining a discharge chamber adapted to receive nad mount u pressurised gas discharge apparatus in operation of the pile driver, a driving head positioned beneath the ria and adapted to be coupled to a pile to be driven, and an upstanding tubular sleeve connected to and extending upwardly froa the head, the wall and sleeve being capable of relative separations! movement froa a first position in which the sleeve surrounds ths outer surface of the wall in close telescoping relationship to essentially dose the discharge chamber, to a second position,in which the discharge chamber is vented, when a charge of pressurised gas is discharged in the discharge chamber, to generate a first pile driving thrust, whereafter the weight and wall are capable of returning downwardly towards the first position to generate a second pile driving thrust.

2. A pile driver as claiaed in claim 1, wherein said aleeve has an Inner surface which is cylindrical adjacent its lower end and ia cooperable with a corresponding cylindrical outer surface of the tubular wall in said first position,the inner surface of the sleeve adjacent its upper end, progressively sloping outwardly in an upward direction to provide an increasing clearance space between the ria and the outwardly sloping zone of the inner surface when the weight and wall have moved upwardly beyond a line where the cylindrical and outwardly sloping zones of the inner surfuce of the sleeve meet. - 21 - 39887

3. A uile driver us claimed in claim 2, wherein the outwardly sloping zone of the inner min'uce of the sleeve is conical with an outward, upward flare.

4. A pile driver as claimed in claim 1, 2 or J, wherein the weight has w passage extending down therein communicating with the discharge chamber, • pipe extending upwardly from the weight, the pipe communicating with the downwardly extending passage, and means for reeding liquid into the nioe to flow down through the downwardly extending passage into the discharge chamber to fill the discharge chamber with liquid.

5. A pile driver as claimed in cluim 4, wherein one or nrr<: passages communicate with the upper end of the disc berg*.- chamber, the passages being dimensional to permit gas to escape from the chamber as the liquid enters the chamber from the downwardly extending passage, but to prevent the escape from the discharge chamber of a quantity of pressurised gas sufficient to significantly reduce the pressure therein when a charge of pressurised gas is discharged in the discharge chamber.

6. A pile driver as claimed in claim 4 or 5, wherein the downwardly extending passage is centrally located in the weight with a plurality of branch passages at its lower end communicating between the discharge chamber and central passage, and > check vulve engageable with the lo*er end of the weight to block the branch passages.

7. A pile driver as claimed In cluim 4, 5 or 6, wherein said means for feeding liquid into ^he pipe to flow down through the downwardly extending. passage includes a stationary liquid supply manifold surrounding the pipe und having first find second spaced sliding seals engaging the pipe defining a oanifolu chtmber in the manifold surrounding the pipe, ;'nd at least one opening ir: th

8. A pilo driver us claimed in claim 4, 5 or 6, whoroin tjoid meuns for feeding liquid into the pipe to flow down through tho downwardly extending pusuuge includes u stationary liquid supply manifold und ut least one slack flexible hose extending from the upper end of the pipe to the manifold.

9. A pile driver us claimed in uny preceding claim, wherein the wall, sleeve und driving head have generally cylindrical surfaces.

10. A pile driver us claimed in -*ny preceding claim, wherein an elongate cylindrical housing surrounds the weight, with the weight being movable up and down within the housing, and the driving head being movably mounted in the lower end of the housing.

11. A pile driver aa claimed in claim 10 in combination with cli im 7 or 8, wherein "he stationary liquid supply manifold is mounted in the upper end of the housing.

12. A pile driver as claimed in claim 10 or 11, wherein ;;n enclosure is connected to the upper end of the housing for catching the liquid expelled up through the clearance space -round the weight, hose line connects the enclosure to <• separator for seruriting the liquid from the gas, and a pump is provided to return the liquid to the pipe.

13. A pile driver as claimed in uny preceding claim, wherein the driving head has an unnular groove therein engugeable by the rim in said first position, and to transmit the second pile driving impulse from the weight to the driving head, the groove being udupted to trap some liquid therein for absorbing shock when the rim impacts down into the groove.

14. A pile driver as claimed in uny preceding claim including a pressurised gas discharge apparatus mounted within the discharge chamber. 38687

15. » A pile driver «s claimed in claia *14 in combination with cl'iin 4, including a hi&b prcs.surc gac supply line connected to the apparatus r-nd oxtending up the p.>aa--ge on the weight, und the pipe, the line being connectiblo to 5 a source of high pressure gnu.

16. A pile driver substantially as hereinbefore described with reference to Figures 1 to 9 or 12 of the accoaponying drawings.

17. * A pile driver as claimed in claim 16, modified 10 substantially as hereinbefore described with reference to Figure 10 of the accoapunying drawings.

18. A pile driver as claimed in claim 16, modified substantially as hereinbefore described tith reference to Figure 11 of the «.ccoaponying drawings. MACLACHLAN & DONALDSON Applicants' Agents 47 Kerrion Square PUBLIB 2. - 24 -