US3788402A

US3788402A - Automatically self-regulating variable-stroke, variable-rate and quiet-operating pile driver apparatus

Info

Publication number: US3788402A
Application number: US00280547A
Authority: US
Inventors: S Chelminski
Original assignee: Bolt Associates Inc
Current assignee: Dow Chemical Co; Bolt Associates Inc
Priority date: 1970-12-29
Filing date: 1972-08-14
Publication date: 1974-01-29
Anticipated expiration: 1991-01-29

Abstract

Automatically self-regulating variable-stroke, variable-rate and quiet-operating pile driver apparatus are disclosed in which a massive piston weight is bounced upon a cushion of pressure fluid, the pile driver advantageously being adapted for operation in four different modes: (1) only double-acting, (2) singleacting automatically converting to double-acting at maximum stroke travel, (3) only single-acting, (4) pre-stressing plus impacting plus thrusting mode, and (5) pile extraction mode. The prolonged downward push resulting from the pressurized fluidcushioned bouncing action is more effective than the conventional sharp hammer-type blow resulting from impact of one solid mass against another. When the pile being driven encounters softer strata in the earth, in the single-acting mode, the stroke of the piston weight automatically shortens while the number of bounces per minute automatically increase thus increasing the rate of the quiet powerful bounce thrusts for driving the pile faster, and when harder strata are encountered, the piston weight automatically bounces higher providing a longer stroke with fewer bounces per minute, thus increasing the force of each quiet powerful thrust for overcoming the increased impedance being encountered. In the double-acting mode, when harder strata are encountered, the velocity and stroke length of the piston weight increase automatically to deliver more powerful thrusts. A relatively large number of driving thrusts per minute can be provided in the double-acting mode by changing the head plug mass to shorten the maximum stroke length to increase the frequency of thrusts per minute. By virtue of the pressure fluid bouncing action imparted to the massive piston weight, the noise of metalto-metal contact blows can be avoided, and in addition a muffler housing surrounding the ports through which the expanded pressure fluid is released muffles the sound of the flow of the fluid, such as air or steam; this muffler also serving to separate lubricating oil from the released fluid. A cylinder bottom assembly below the bounce chamber is coupled to the pile being driven to transmit the quiet powerful bounce thrusts to the pile, moving in accordance with the pile motion, and a driving fluid storage chamber and valve mechanism associated with this assembly control the flow of the pressure fluid in an automatically selfregulating manner to seek the most effective driving action from moment-to-moment as the pile encounters different strata. If desired, the bouncing action of the cushion of pressure fluid can be altered to permit the piston weight to strike bottom slightly to provide the driving mode (4) above. A self-contained lubrication system may be actuated by the pressure impulses in the bounce chamber.

Description

United States Patent 1 Chelminski AUTOMATICALLY SELF-REGULATING VARIABLE-STROKE, VARIABLE-RATE AND QUIET-OPERATING PILE DRIVER APPARATUS [75] Inventor: Stephen V. Chelminski, West Redding, Conn.

[73] Assignee: Bolt Associates, Inc., Norwalk,

Conn.

[22] Filed: Aug. 14, 1972 [21] Appl. N0.: 280,547

Related US. Application Data [62] Division of Ser. No. 102,325, Dec. 29, 1970, Pat. No.

12/1968 Duyster etal. 61/535 X Primary ExaminerErnest R. Purser Attorney, Agent, or FirmRoland T. Bryan et a1.

[ 5 7 ABSTRACT Automatically self-regulating variable-stroke, variablerate and quiet-operating pile driver apparatus are disclosed in which a massive piston weight is bounced upon a cushion of pressure fluid, the pile driver advantageously being adapted for operation in four different modes: (i) only double-acting, (2) single-acting automatically converting to double-acting at maximum stroke travel, (3) only single-acting, (4) pre-stressing plus impacting plus thrusting mode, and (5) pile extraction mode. The prolonged downward push resulting from the pressurized fluid-cushioned [111 3,788,402 Jan. 29, 1974 bouncing action is more effective than the conventional sharp hammer-type blow resulting from impact of one solid mass against another. When the pile being driven encounters softer strata in the earth, in the single-acting mode, the stroke of the piston weight automatically shortens while the number of bounces per minute automatically increase thus increasing the rate of the quiet powerful bounce thrusts for driving the pile faster, and when harder strata are encountered, the piston weight automatically bounces higher providing a longer stroke with fewer bounces per minute, thus increasing the force of each quiet powerful thrust for overcoming the increased impedance being encountered. In the double-acting mode, when harder strata are encountered, the velocity and stroke length of the piston weight increase automatically to deliver more powerful thrusts. A relatively large number of driving thrusts per minute can be provided in the double-acting mode by changing the head plug mass to shorten the maximum stroke length to increase the frequency of thrusts per minute. By virtue of the prescylinder bottom assembly below the bounce chamber is coupled to the pile being driven to transmit the quiet powerful bounce thrusts to the pile, moving in accordance with the pile motion, and a driving fluid storage chamber and valve mechanism associated with this assembly control the flow of the pressure fluid in an automatically self-regulating manner to seek the most effective driving action from moment-to-rnoment as the pile encounters different strata. If desired, the bouncing action of the cushion of pressure fluid can be altered to permit the piston weight to strike bottom slightly to provide the driving mode (4) above. A selfcontained lubrication system may be actuated by the pressure impulses in the bounce chamber.

19 Claims, 21 Drawing Figures This is a division of application Ser. No. 102,325, filed Dec. 29, 1970, and now US. Pat. No. 3,714,789.

BACKGROUND INFORMATION Conventional pile drivers of the diesel type use a falling piston or those of the steam type use a falling ram of great weight to strike down upon an anvil surface to transmit the blow to the pile. Such conventional pile drivers have a disadvantage in the fact that they transmit the energy of the falling mass by a striking-type blow on an anvil surface. Each blow produces a very loud noisy sound of metal-to-metal contact which is annoying to many persons, including persons who are located at a relatively great distance from the construction site. This noisy blow, especially in the conventional steam-type open striking hammer, is, in my opinion, a relatively unsatisfactory method of transmitting energy to the pile for the purpose of driving the pile, because of the suddenness and short duration of this type of blow. Also, the forces on the anvil and on the pile become destructive when the energy levels needed to drive a pile become high.

Because of the metal-to-metal contact, the impact tends to be destructive to the pile driver itself and to the pile being driven. There are many instances when shock-absorbing materials must be interposed between the striking parts and the pile. The shock-absorbing materials which are conventionally used are wooden blocks, or pads, of phenolic laminates, or other plastic materials. The use of such shock absorbers wastes energy, and since they areexpendable and need to be replaced, there is a resulting added cost for the pile driving operation.

It can be said that the prior art pile drivers are ofte noisy.

Another disadvantage inherent in the conventional steam-type pile driver lies in the longer period of time it takes for this type of driver to raise its hammer weight up from the anvil to the top of its travel before releasing the steam to expand to atmospheric pressure. The re lease of the steam drops the hammer weight to fall upon the anvil.

As further background information, it is noted that there is an advantage in providing a relatively large number of driving thrusts per minute to a pile being driven. The reason for this advantage is that the soil adjacent to the pile remains in a more or less agitated state when frequent driving thrusts are applied to the pile. Consequently, the frictional force is reduced and the pile is relatively easier to drive. Conversely, when the driving thrusts are less frequent, the soil adjacent to the pile has an opportunity to slump down to become morefirmly seated against the side surfaces of the pile, which increases the frictional force so as to make the pile much more difficult to drive.

DESCRIPTION Accordingly, it is among the objects of the present invention to avoid undue noise, to overcome other disadvantages of the prior art, and to provide more effective and efficient pile-driving operations.

Other objects of the present invention are to provide a novel advantageous and effective automatically selfregulating variable-stroke, variable-rate and quietoperating pile driver method and system wherein a massive piston weight is bounced upon a cushion of pressure fluid.

It is an advantage of a pile driver embodying the present invention that a prolonged downward push or thrust results from the pressurized fluid-cushioned bouncing action of the massive piston weight assembly. This prolonged downward push or thrust is more effective and more efficient than the conventional sharp hammer-type blow resulting from impact of a solid mass against an anvil. This prolonged downward push or thrust is less damaging to the pile driver and to the pile than the sharp hammer-type blow of a solid mass against an anvil which is typical of many prior art pile drivers.

Among the advantages of the present invention in certain of its aspects is that the pile driver embodying these aspects of the invention is adapted for operation in five different modes: (l) solely double-acting, (2) single-acting automatically converting to double-acting at the maximum stroke travel, (3) only single-acting, (4) pre-stressing plus impacting plus thrusting mode, and (5) in a pile extraction mode.

Among the advantages provided by the pile driver methods and systems embodying the present invention are those resulting from the fact that in the singleacting mode when the pile being driven encounters softer strata in the earth, the stroke of the piston weight automatically shortens while the number of bounces per minute automatically increase, thus increasing the rateof the quiet powerful bounce thrusts for driving the pile faster. When harder strata are encountered, the piston weight automatically bounces higher providing a longer stroke with fewer bounces per minute, thus increasing the force of each quiet powerful thrust for overcoming the increased impedance being encountered.

[n the double-acting mode, when harder strata are encountered, the velocity and stroke length of the piston weight automatically increase to deliver more powerful driving thrusts. A relatively large number of driving thrusts per minute can be provided in the doubleacting modeby changing the head plug mass to shorten the maximum stroke length to increase the frequency of thrusts per minute.

Another advantage is that a pile driver, according to the present invention, can be equipped with a muffler housing surrounding the ports through which the expanded pressure fluid is released to muffle the sound of the escaping pressure fluid, such as air or stream. The

muffler also can be used to separate lubricating oil from the released fluid.

Among the further advantages provided by the present invention is that the quiet, powerful driving thrust applied to the top of the pile endures for a longer period of time during each driving bounce, and destructive forces on the pile are substantially reduced as comparedto a prior art impact-type pile driver providing a comparable driving rate.

In accordance with one aspect of the present invention, there is provided a controlled release of pressure fluid into the bounce chamber beneath the massive piston weight to transfer the kinetic energy of the falling piston weight to the pile at a controlled rate to lower the amount of destructive forces being applied to the pile while lengthening the useful driving push being ap- 3 plied to the pile. The pressurized driving fluid is released into the bounce chamber from a driving energy chamber. This driving energy chamber is positioned closely adjacent the bounce chamber, and it is adapted to communicate directly with the bounce chamber when a release valve is actuated by the piston weight. Moreover, the piston weight is reaccelerated upwardly, in a bounce by a cushion of the pressure fluid, thereby providing further extension in time of the useful driving thrust, thereby driving piles in an effective and. efficient method.

In accordance with the present invention, there is a self-regulating distribution of the driving energy between the bouncing massive piston weight andthe cylinder bottom assembly which is coupled to the pile. When the pile is being driven through relatively soft material, affording low impedance to the penetration of the pile, the injected pressurized fluid in the bounce chamber is able to push the cylinder bottom assembly downwardly a greater distance. Thus, during the bounce, there is an increased relative expansion of the pressurized fluid downwardly and a corresponding decreased relative amount of expansion thereof upwardly as the pressure fluid in the bounce chamber reaccelerates the massive piston weight upwardly. There is a less resultant upward velocity of the piston weight, and its stroke (or travel) is correspondingly relatively short. In the single-acting mode, this short stroke provides a relatively rapid cycle time as compared to a longer stroke.

When harder strata are encountered by the pile, affording a greater impedance to its penetration, the pressurized fluid in the bounce chamber pushes the cylinder bottom assembly downwardly a shorter distance. Thus, during the bounce, there is a decreased relative expansion of the pressurized fluid downwardly. A corresponding increased relative amount of upward expansion of the fluid occurs as it re-accelerates the piston weight upwardly. The result is that there is increased upward velocity of the piston weight. Accordingly, its stroke is increased so that it goes higher in the upper cylinder. It thereby accumulates more potential energy to be applied to driving the pile during the next bounce to provide a more powerful thrust. This increase in driving thrust occurs for both the singleacting or double-acting modes. The foregoing two paragraphs explain my theory of the self-regulating distribution of the driving energy between the bouncing massive piston weight and the cylinder bottom assembly, as occasioned by the impedance being encountered by the pile.

In addition, it is noted that the energy provided by the injected pressurized fluid is effectively utilized because the portion of this energy which was not used to drive the pile is employed to re-accelerate the piston weight upwardly at an increased velocity.- Thus, this portion of the energy is substantially conserved (minus friction and heat losses) by being converted into increased potential energy to be utilized to provide a more powerful thrust on the next bounce.

The deceleration and re-acceleration of the massive piston weight effectively utilizes not only the force applied in decelerating the piston weight at the end of its downward stroke, but also effectively utilizes the reaction to the re-accelerating force applied to the piston weight during the period of time such force is being applied to the piston mass to re-accelerate it up again toward the top of its stroke. Thus, an enduring downward thrust or push is created during the entire deceleration and re-acceleration.

If desired, the bouncing action of the cushion of pressure fluid in the bounce chamber can be altered to permit the piston weight to strike bottom slightly. The resulting driving mode on the pile is to pre-stress the pile, then impact, then thrust it down. The pre-stressing occurs while the cushion of pressure fluid is decelerating the piston. This pre-stressing removes all of the play between the cylinder bottom assembly and the pile. Then, when the piston weight strikes bottom with an impact, the resulting blow starts the pile moving downwardly. The subsequent re-acceleration of the piston weight upwardly by the pressure fluid provides an enduring thrust which continues to push the moving pile down further.

In the presently preferred embodiment, the cylinder bottom assembly includes a second piston located below the bounce chamber in which the pressure fluid operates. This second piston is coupled to the pile being driven to transmit the quiet powerful bounce thrusts to the pile, moving in accordance with the pile motion. A driving energy pressurized fluid chamber is associated with this second piston and a valve mecha nism injects a quantity of the pressure fluid automati cally from the driving energy chamber into the bounce chamber. A self-regulating driving action occurs as explained above to seek the most effective driving action from moment-to-moment as the pile encounters different strata.

An advantageous self-contained lubrication system is actuated by the pressure impulses in the bounce chamher.

A muffler housing surrounds the ports through which the expanded pressure fluid is discharged into the atmosphere to muffle the sound of the flow of fluid. This muffler also serves to separate the lubricating oil from the discharged fluid so as to recaptrue the lubricating oil. This recaptured oil is returned to the self-contained lubricating system for re-use therein,

Additional advantages flowing from this invention are simplicity and reliability of design and construction of the pile drivers with very few moving parts.

The pressure fluid utilized can be compressed air or steam or any other suitable pressurized gas or vapor. As i used herein, the term pressurized fluid or pressure fluid isintended to include compressed air, steam or other suitable pressurized gas or vapor. In the illustrative embodiments shown, it is my preference to utilize compressed air as the pressurized fluid" to operate the pile driver.

The various features, aspects and advantages of the automatically self-regulating variable-stroke, variablerate and quiet operating pile driver method and system of the present invention will become more fully appreciated from a consideration of the following detailed description in conjunction with the accompanying drawings, in which:

FIG. 1 is a side elevational view of a pressure fluid actuated pile driver system embodying the present invention, shown on greatly-reduced scale from actual size;

FIG. 2 is a cross-sectional view taken along the line 22 in FIG. 1 as seen looking downward, being shown on a slightly larger scale than FIG. 1;

FIG. 3 is a vertical axial sectional view, shown somewhat further enlarged, with the massive piston weight the muffler housing taken along the line 6-6 in FIG. 5.

FIG. 7 is an elevational sectional view of the portion of the pile driver system containing the oil filter and the self-actuated lubrication pump for supplying lubricating oil to the moving parts of the pile driver. FIG. 7 is drawn on a scale of approximately one-half actual size;

FIG. 8 is an elevational sectional view of the inlet arrangement for the pressurized fluid, with the connection for injecting the lubricating oil into the pressure fluid being shown;

FIGS. 9, 10, 11, 12, 13 and 14 are vertical axial sectional views similar to FIG. 3, but shown on somewhat smaller scale than in FIG. 3. These FIGS. 9, 10, 11, 12, 13 and 14 show the successive operating positions of the few moving parts of the pile driver system occurring during one cycle of operation for delivering a powerful push or thrust to the pile being driven. It is noted that the operating positions shown in FIG. 3 are intermediate those shown in FIGS. 9 and 10;

FIG. 14 shows the massive piston weight being operated in the double-acting mode;

FIG. 15 is a vertical axial sectional view of the upper portion of the pile driver, with the operation being in the single-acting mode;

FIG. 16 is similar to FIG. 15, except that the operating mode is single-acting converting to double-acting at maximum stroke travel as shown;

FIG. 17 is a side elevational view of the pile driver operating in the extraction mode with a pressure fluid cylinder and piston included in the suspension line for limiting the maximum load applied to the suspension equipment, such as a crane, and for isolating the suspension from the jarring effects of the pile driver acting in the extraction mode;

FIG. 18 is a side elevational view and partial sectional view as seen along the line 18-18 in FIG. 17;

FIG. 19 is an elevational sectional view of the pile driver adapter and conical guide used for driving wooden piles;

FIG. 20 is a vertical axial sectional view showing a modified embodiment of the invention; and

FIG. 21 is a vertical axial sectional view of another embodiment.

With reference to FIGS. 1-4, an automatically selfregulating variable-stroke, variable-rate and quiet op erating pile driver method and system 20 are shown embodying the present invention. The pile driver system-20 comprises a cylinder wall 22 surrounding a cylinder 23 provided with a massive piston weight assembly, generally indicated at 24 (See FIG. 3). At the lower end of the cylinder wall 22 is a'cylinder bottom assembly, generally indicated at 26, effectively closing offthe lower end of thecylinder wall 22. The cylinder bottom assembly 26 is coupled to the pile 28 being driven by a detachable coupling 30 and a pile-driving adapter 32 which is shaped so as to engage the upper end of the particular pile being driven.

When it is desired to drive a pile having a different size or a different configuration (such as pipe pile, H- beam pile, timber pile) then the coupling 30 is temporarily disconnected, and a different adapter 32 is inserted for providing the desired engagement with the pile. A pipe pile 28 is shown in FIGS. 1 and 3, but this is illustrative only. It is to be understood that the present invention can be used to advantage for driving any type of drivable pile.

There is a bounce chamber 34 (FIG. 3) which is lo cated within the cylinder wall 22 between the lower end of the massive piston weight assembly 24 and the cylinder bottom assembly 26. Pressure fluid injection means 36 are provided for suddenly injecting pressurized fluid into the bounce chamber 34 beneath the descending piston weight assembly 24. This fluid injection means 36 includes a pressurized driving fluid storage chamber 38 and a control valve mechanism 40 which communicates with the bounce chamber 34.

The massive piston weight assembly 24 moves up and down within the cylinder 23, and it bounces upon a cushion of pressurized fluid in the bounce chamber 34. The manner in which the pressurized fluid is injected into the bounce chamber, and the many advantages which accrue from the advantageous massive piston bouncing action are indicated in the introduction and will be described further below.

The massive piston weight assembly 24 includes a main weight 42 of suitable massive and strong material. For example, in this illustrative embodiment, the main weight 42 is a solid steel member of generally cylindrical configuration with bearings, piston rings and end caps attached to its lower and upper ends. Its lower and upper ends are identical in construction, and so only the lower end is shown in detail in FIG. 3 in order to simplify and clarify the drawings. If it is desired to see the upper end of the piston weight assembly 24, it is noted that this can be seen in FIGS. 2, 14, 15, and 16.

Referring particularly to FIGS. 3 and 7, it is seen that a bearing sleeve member 44 is mounted on each end of the main weight 42. This sleeve member 44 has an annular configuration and fits onto a reduced diameter end portion 46 at the end of the weight 42, abutting against an annular shoulder 48. This bearing sleeve member 44 is formed of suitable bearing material to run against the cylinder wall 22, for example, it is formed of bearing bronze. It is retained by an end cap 50 of tough hardened steel secured to the weight 42 by detachable fastening means shown as a plurality of machine screws 52.

In order to form a fluid seal near the end of the piston weight assembly 24, a plurality of piston rings 54 are provided. These piston rings 54 are mountedv in an annular gland member 56 which is retained by the end cap 50 together with the bearing sleeve 44. There is a the rings 54 with accurate firm support, because the the floating gland 56 and the cylinder wall. Thus, the piston rings continue to be well supported tolast a long time. The way in which the piston rings and gland are assembled is that the piston rings are split so as to be inserted into the grooves in the annular gland; whereas the gland 56 itself has a continuous circular configuration and is placed adjacent to the bearing sleeve 44 before the end cap 50 is secured in place. There is a close fit between the end cap 50 and the lower radial surface of the gland member 56 and also a close fit between the bearing member 44 and the adjacent upper radial surface of the gland member. Thus, an effective fluid seal is provided by the piston rings 54 and the gland 56 even though there is a large clearance space 58 beneath the gland.

In my presently preferred illustrative embodiment as shown, the cylinder bottom assembly 26 includes a second piston 60. This second piston 60 is adapted to move up and down for'a'limited travel distance within a second cylinder 61 which is defined by a lower extension of the cylinder wall 22 below the level of the bounce chamber 34. To retain the piston 60 within the cylinder 61, there is an annular stop shoulder 63 surrounding the piston 60. An annular retainer and bearing element 65 defines the lower end of the cylinder 61. The retainer and bearing element 65 is secured by large machine screws 67 to a mounting ring 69 which is welded to the exterior of the cylinder wall 22. At the lower end of the piston 60, there is a coupling flange 71 adapted to be gripped by the detachable coupling 30. The detachable coupling 30 is formed by two semicircular clamps with protruding mating flanges 73 which are secured together by bolts 75.

As an alternative embodiment shown in FIG. 21, it is noted that the cylinder bottom assembly 26 can be defined by a closed lower end of the cylinder 22. In other words, in such an alternative embodiment, the second piston 60 is replaced by a fixed member 60A which is welded or otherwise attached to the lower portion of the cylinder wall 22, so as to be effectively integral with the cylinder wall 22.

It is my present preference to utilize a cylinder bottom assembly 26 which includes a relatively movable second piston 60, because the use of this second piston 60 de-couples the cylinder wall 22 from the pile 28. this de-coupling of the cylinder wall 22 from the pile 28 reduces the amount of mass tobe driven downwardly when the powerful driving thrust is applied to drive the pile 28. i

As explained above, the fluid injection means 36 includes the driving fluid chamber 38 and the control valve mechanism 40. It is the'purpose of this fluid injection means 36 to inject pressurized fluid through an injection port 62 into the bounce chamber 34 beneath the descending piston weight assembly 24. The injection of the pressure fluid is controlled by the valve mechanism 40.

The driving fluid chamber means 38 is located within the second piston 60 of the cylinder bottom assembly 26. The chamber bore 64 is lined by a cylinder sleeve 66. A bottom flange 68 of an upstanding valve stem guide 70 lines the bottom of the driving fluid chamber 38. The guide 70 has a bore 72, and a valve stem 74 of valve member 76 extends into this bore 72. The valve member 76 has a conical valve surface 78 which seats upwardly against a conical valve seat 80 formed in the end cap 82 of the second piston 60. This second piston is provided with a bearing sleeve member 84, piston rings 86 and an annular gland 88 having annular clearance 58 similar to those elements for both ends of the piston weight assembly 24.

In order to actuate the valve mechanism 40 by the piston weight 24, there is an upwardly extending actuator 91 integral with the valve member 76. The actuator 91 is equipped with pressurized fluid trapping means 93 in the form of an enlarged cylindrical plunger. This plunger 93 can be depressed to fit snugly into the port 62 to trap pressurized fluid in the bounce chamber 34.

When the valve member 76 is depressed away from its valve seat 80, pressurized fluid in the driving fluid chamber 38 can rush up through multiple channels (FIG. 4) to bypass the perimeter of the valve member 76 so as to be injected through the port 62 into the bounce chamber 34. The channels 90 are formed by grooves between lands 92 in the interior of the cylinderical liner 66.

The pressurized fluid is supplied from a suitable source, for example, such as the pressure storage tank (not shown) of an air compressor (not shown). The compressed air is at a suitable pressure of, for example, 80 pounds per square inch (p.s.i.) to 3,000 p.s.i.

When the valve member 76 is depressed, its annular groove 95 (FIG. 3) cooperates with the upper end of the valve guide 70 (as seen in FIG. 12) to act as resilient deceleration means by trapping fluid in the groove 95. This trapped fluid provides resilient deceleration for the depressed valve member to prevent its banging down on the guide 70.

The pressurized fluid is fed to, the pile driver system 20 through a flexible pressure hose line 94 and through a connection fitting 96. This fitting 96 feeds into an input passage 98 which'communicates with the bore 72 of the valve stem guide 70. The pressurized fluid from the bore 72 flows through a constricted passageway 100 into the driving fluid chamber 38. When the valve stem 74 is in its uppermost position as shown in FIG. 3, the pressurized fluid can also flow through a less restricted passageway 1 or into the chamber 38. The two passageways 100 and 102 are in parallel flow relationship; the lower constricted one 100 is always open, but the upper unrestricted one 102 is shut off when the valve member 76 together with its stem 74 is depressed by the piston weight 24.

After the piston weight 24 has bounced upwardly from the cushion of pressurized fluid, as shown in FIG. 13, the expanded pressure fluid 104 is released from the cylinder 23 through a plurality of outlet ports 106 in the cylinder wall 22. The outlet ports 106 communicate with an annular muffler chamber 108 defined by a removable muffler housing 109 which includes a pair of spaced

cylindrical walls

110 and 112. The

muffler housing walls

110 and 112 are rigidly interconnected by a bottom ring plate 1 14 which is detachably secured to a mounting ring 116 by a pluralityof bolts 118. The mounting ring I 16 is secured to the outside of the cylinder wall 22 by welding. I

Shown in FIGS. 5 and 6 is the upper end of the re movable muffler 109. The annular muffler chamber 108 communicates through multiple ports 120 with a quantity of oil air separating material 122 in the top of an annular muffler chamber 123 for separating droplets of lubricating oil from the expanded pressure fluid 104 after passing through the ports 120. The material 122 is coarse stainless steel wool matting. A removable cover 124 secured by screws 126 enables the oil separating material 122 to be removed and replaced.

The expanded pressure fluid 104 flows down through the material 122, then down through the multiple holes 127 in a material support ring 129, and as shown in FIG. 6, the fluid 104 then flows into an inverted U- shaped fluid outlet baffle 128. The interior of the baffle 128 communicates with an atmospheric vent 130 through which the expanded pressure fluid passes out into the atmosphere. The purpose of the baffle 128 is to prevent the separated oil droplets from being blown out into the atmosphere.

As shown in FIG. 6, the separated oil droplets 132 fall from the separation material 122 in the chamber 123; and as shown in FIG, 3, this oil collects in an annular reservoir 134 at the bottom of the chamber 123. Thus, an oil reservoir is provided for the self-contained lubrication system which will be explained further below.

The muffler housing 109 can be removed to provide access to the ports 106, if desired, by unscrewing the bolts 118 (FIGS. 3 and 7). As shown in FIG. 6, the top of the muffler housing 109 has an O-ring seal 136 for sealing the muffler chamber 108. Thus, the seal 136 can be slid up along the exterior of the cylinder wall 22 for removing the muffler housing 109. With reference to FIG. 1, the mounting 138 for the lead guides and the upper muffler and air filter 140 can be removed so as to permit complete removal of the muffler housing 109, if desired.

The self-contained lubrication system is shown in greatest detail in FIGS. 7 and 8. The level of the oil in the reservoir 134 can be seen by observing an oil gauge 135 having a transparent non-breakable plastic tube. Oil from the reservoir 134 can flow down through an oil supply passage 142 into an inlet passage 144 sealed by a seal 145 and communicating with the inlet chamber 146 of an oil filter assembly 150. An annular filter cartridge 148 of filter material such as felt separates the inlet chamber 146 from an outlet chamber 152 through which passes the end cap retainer bolt 154. The filter element 148 can be removed and replaced by unscrewing the bolt 154 and removing the cap 156 and its associated

oil lines

158 and 159.

The filtered oil is fed from the outlet chamber 152 through a passage 157 in the cap and through

oil feed lines

158 and 159 leading to an oil pump 160. The line 158 feeds through a check valve 162 into a lowpressure pump chamber 164 containing a pump piston 166. This piston 166 pumps oil at low pressure through a check valve 168 and through an oil line 170 extending up to an oil hole 172' (FIG. 1) for dispensing lubricating oil above the piston weight assembly 24 to lubricate the piston 24 and cylinder wall 22.

The other feed line 159 feeds through a check valve 174 into a high-pressure pump chamber 176 containing a smaller diameter piston 178. This piston 178 pumps oil under high pressure through a check valve 179 into an oil line 180 extending down to a swivel 182 (FIG. 8) on the inlet connection fitting 96 for the pressurized fluid. The swivel 182 has a passage 183 and an annular channel 184 for feeding oil inward through a pair of oil holes into the bore 97 of the fitting 96.

Thus, the lubricating oil is mixed with the incoming pressurized fluid, and thereby oil is dispensed up through the passage 98 so as to lubricate the fluid injection means 36 including the valve mechanism 40. this 10 oil entering through the passage 98 also serves to lubricate the bounce chamber 34, the piston 60 and the cylinder wall 22 surrounding the piston 60.

Inviting attention again to FIG. 7, it is noted that

pistons

166 and 178 are connected together to form a double piston. A spring 186 in the low-pressure pump chamber 164 urges both

pistons

166 and 178 toward the left. In other words, the spring 186 urges the

pistons

166 and 178 in the direction of their intake stroke. The high pressures occuring in the bounce chamber 34 are utilized to drive the

pistons

166 and 178 toward the right, i.e. in the direction of their expulsion (pumping) stroke. a small port 188 in the cylinder wall 22 communicates through drilled passages 189 in a base plate 190 with a passage 192 leading into the piston-actuating chamber 194. The base plate 190 serves to support both the oil filter assembly and the oil pump 160. This base plate can be detached from the outside of the cylinder wall 22. As shown in FIG. 3, this base plate is removably secured by machine screws 196 (only one can be seen in FIG. 3).

When driving a pile, as shown in FIGS. 1 and 2, the pile driver system is guided by a pair of spaced parallel

vertical guide rails

200 and 201, which are called leads. The use of leads is well known in the art of driving piles, and their usage is not claimed as novel. These leads are engaged by lower and

upper guides

204 and 206 which straddle the respective leads and are greased so as to slide easily down along the leads. The lower pair of guides 204 are attached by a mounting clamp ring 208 (FIG. 2) which surrounds the muffler housing 109. This lower mounting clamp ring 208 is formed in two semi-circles with protruding mating flanges 209 secured together by bolts 210. Similarly, the upper pair of guides 206 are attached by a mounting clamp ring 138 surrounding the cylinder wall 22. The upper clamp ring 138 is formed in two semi-circles with protruding mating flanges 213 secured together by bolts 214.

In order to allow atmospheric air to flow in and out of the upper portion of cylinder 23 above the piston weight 24, there are provided a plurality of vent ports 216 (FIG. 15) communicating with an annular muffler and air filter housing 140. This housing defines inner and outer

annular muffler chambers

218 and 220. FIG. 15 shows the atmospheric air 222 being expelled from the cylinder 23, because the piston weight 24 is rising.

It will be understood that as soon as the piston 24 begins descending again, the atmospheric air will be sucked back into the cylinder 23. To exclude dust and dirt there is an air. filter element 224 in the chamber 220 adjacent to the atmospheric vent 226.

In order to provide various driving modes for the pile driver system 20, various sizes of head plugs 230 (FIG. 15), 230A (FIG. 1 are utilized. The head plugs are removably secured in the top of the cylinder wall 22, by detachable fastening means 232 shown as machine screws. The deep head plug 230A shown in FIG. 1 extends down so far that it blocks the vent ports 216, thus producing the double-acting driving mode, as will be explained in detail further below.

The shallow head plug shown in FIG. 15 produces a single-acting driving mode.

When the piston weight assembly 24 makes extreme upward excursions within the cylinder 23, as shown in FIG. 16, then the single-acting driving mode automatically converts to a double-acting mode.

In use, the pile driver system 20 (FIG. 1) or 20A (FIG. 20) or 208 (FIG. 21) can be supported by a cable 236 (FIG. 1) from a suitable crane (not shown) attached to suitable support means (234), such as connection means attached to the upper end of the pile driver, for example, to the

head plug

230 or 230A.

When used in the pile-extraction mode, as shown in FIGS. 17 and 18, the support cable 236 can advantageously be fastened to connection means 238 attached to a pressure-fluid cylinder 240 having a piston 242 therein with a chamber 244 below the piston. The'piston rod serves as support means 234 attached to the upper end of the pile driver. Pressurized fluid, for example, such as compressed air or other gas under pressure, is supplied from a pressurized fluid source 246, such as the receiver of an air compressor. This pressurized fluid is supplied through an adjustable pressure regulator 248 into the cylinder chamber 244.

The regulator 248 is adjusted by the operator such 1 that the total force developed by the pressurized fluid in the chamber 244 acting upwardly upon the working area of the piston 242 is moderately less than the safe maximum lifting load of the crane pulling on the cable 236.

It will be understood that when acting in the pileextraction mode (as shown in FIGS. 17 and 18) a large upward pull is being exerted by the cable 236, and the pile driver is arranged to deliver jarring upward blows so as to extract the pile 28. Thus, by regulating (248) the pressure, the fluid cylinder and

piston

240, 242, 244 serve as overload protection means for the crane (or other lifting means being used). Also, this fluid cylinder and piston serve as mechanical shock absorber means, because the fluid (air or gas) in the chamber 244 is compressible and serve as a resilient support. In this way the cable 236 and crane or other lifting means are spared from experiencing the wear and tear which would otherwise result from the jarring action of the pile driver. I

In the pile extraction mode, the reciprocating piston weight 24 travels up, as shown in FIG. 16, near to the head plug 230, such that the trapped compressed air (shown by double-headed arrows) in the upper end of the cylinder 23 beneath the head plug 230 exerts an upward thrust on the pile driver during each stroke of the piston weight 24. If desired, the upper end cap 50 of the reciprocating piston weight 24 can be arranged to strike up against the head plug 230 to exert an upward impact for jarring the pile loose. This upward striking is accomplished by installing a head plug which extends down to the level of the vent ports 216.

The upward pull of cable 236 (FIG. 17) on the pile driver causes the annular shoulder 63 (FIG. 18) of the second piston 60 to engage theretainer stop and bearing element 65. There is a loose coupling 250 which is connected by the coupling 30 to the cylinder bottom assembly 60. This loose (or overriding) coupling 250 permits downward motion of the cylinder bottom assembly 60 without imposing any downward thrust on the pile 28. However, the upward thrust occurring at the peak of each upward stroke of the piston weight 24 is transmitted by the coupling 250 to the pile '28 being extracted.

As an example, the pile 28 (FIGS. 17 and 18) is shown as an H-beam pile, but other types of piles can also be extracted with advantage by use of the invention.

The loose coupling 250 is shown as including a cylinder having an abutment 254 at its lower end. An extractor rod 256 is attached to the pile 28 being extracted. A head 252 on this rod strikes against the abutment 254for delivering upward thrusts to the pile for extracting it.

FIG. 19 shows the pile driver system 20 (FIG. 1) or 20A (FIG. 20) or 203 (FIG. 21) being used for driving a timber pile 28. A conical guide 258 is shown for centering the

pile driver

20, or 20A, or 203 upon the timber pile 28. The guide 258 is secured by a clamp to an With reference to FIG. 20, a modified pile driver sys- I tem 20A is shown embodying the invention and adapted for practicing the method of the invention.

The only change from 'the pile driver system and method 20, as described above, is that the valve actuator 91A does not include fluid-trapping means in the form of an enlarged head such as shown at 93 (FIG. 3).

Thus, in FIG. 20, when the piston weight assembly 24 descends, it is decelerated by the pressure fluid in the bounce chamber and thereafter forces this fluid back down into the driving fluid storage chamber 38. Impact at reduced velocity is thereby allowed to occur between the piston weight 24 and the second piston 60. Thereafter, the piston weight 24 is re-accelerated upwardly by pressure fluid released by open valve 40 from the driving fluid chamber 38.

Accordingly, it will be understood that FIG. 20 is well adapted to provide the fourth mode set forth in the introduction, namely, pre-stress plus impact plus thrust. The pre-stressing occurs while the cushion of pressure fluid injected into the bounce chamber by the valve means 40 plus any residual fluid in the bounce chamber is decelerating the piston weight. This pre-stressing removes all of the play between the second piston 60 and the pile 28. Then, when the piston weight 24 strikes the second piston 60 with an impact, as shown in FIG. 20, the resulting blow starts the pile moving downwardly, as indicated by the twin arrows near the coupling 30 in FIG. 20. Following impact, there is a powerful thrust delivered to the moving pile to keep it moving down in a highly effective driving mode. This powerful enduring thrust is delivered to the pile during the reacceleration of the piston weight upwardly.

There is an advantageous method for increasing or decreasing the amount of impact occurring in the system 20A of FIG. 20. The actuator 91A is lengthened to decrease the amount of impact and is shortened to increase the amountof impact. This lengthening or shortening is accomplished by removing the valve member 76 and replacing it with one having a longer or shorter actuator 91A, as desired.

When a longer actuator 91A is employed, the valve 40 is opened to inject the pressurized fluid beneath the descending position weight 24 when it is farther from the cylinder bottom assembly 60. The pressurized fluid thereby has a longer time to act and thus decelerates the piston weight 24 to a slower velocity before impact occurs, producing a reduced impact, and vice versa.

If a sufficiently long actuator 91A is employed, then impact will not occur, provided that the fluid driving chamber 38 is sufficiently large to adequately fill the bounce chamber with pressurized fluid at a sufficient 13 pressure to completely decelerate the piston weight in the time available.

This pre-stress plus impact plus thrust driving mode can be used to advantage for driving very stubborn piles. The amount of impact can be adjusted, in the manner explained above, so as to start the pile moving. Then the pile driver provides a powerful, enduring thrust to push the moving pile on down further in an effective efficient operation. The amount of impact can be just sufficient to start the pile moving, being very effective because the pile is already pre-stressed. Thus, excessive impact as occurs in the prior art is avoided. The powerful, enduring after thrust is very effective because it is delivered to an already moving pile.

With reference to FIG. 21, another modified pile driver system B is shown embodying the invention and adapted for practicing the method of the invention. The only change from the pile driver system and method 20, is that the cylinder bottom assembly 60A in the system 208 is secured to the lower end of the'cylinder wall 22. This cylinder bottom assembly is attached by a large number of strong machine screws 262. This attachment is an advantage because it reduces the number of moving parts in the pile driver system to two, namely, the piston weight assembly 24 and the valve member 76. (In counting the moving parts as two, the

lubrication system

150, 160 is not being counted, because the lubrication system is shown as an advantageous feature of the embodiments shown. However, other conventional lubrication systems could. be employed.)

It is my present preference to use the

pile driver system

20 or 20A which has three moving

parts

24, 60 and 76, because the movement of the cylinder bottom 60 reduces the effective mass to be driven by de-coupling the mass of the cylinder wall 22 (together with everything rigidly attached to the wall 22) from the pile being driven, thus making the driving job correspondingly easier. However, in certain pile driving applications, the advantage of fewer moving parts may outweigh the advantage of reduction of the effective mass being driven.

Further Aspects of Operation A number of the operational features and advantages of this invention are explained above in connection with the description of the method and systems shown. Further aspects of the operation are set forth in this part of the specification.

When the

pile driving systems

20, 20A or 20B are set up ready to drive a pile, the reciprocating up-and-down motion of the massive piston weight 24 is started as follows: Initially the piston weight 24 is resting down stationary upon the cylinder

bottom assembly

60 or 60A, as the case may be. Thus, the valve actuator 91 or91A is depressed so that the valve member 76 is spaced from its seat. There is a modest clearance around the enlarged head 93 so that fluid can leak from the pressure fluid driving chamber 38 into the bounce chamber sure fluid storage chamber 38 is now supplied with '14 pressurized fluid through the constricted passage 100 (FIG. 3). (Large passage 102 is now blocked by the stationary depressed stem 74.)

In the system 20 or 20B, the pressurized fluid enters the bounce chamber by leaking through the clearance around the plunger head 93. The piston weight 24 is raised up by the entering fluid, and the pressure fluid in the bore 72 acts on the stem 74 to cause the valve member 76 to move up together with the piston weight 24. When the head 93 leaves the injector port 62', the accumulated pressure fluid in the chamber 38 rushes up into the bounce chamber 34 to suddenly push the piston weight up. The valve member 76 rises up against its seat to close the valve 40. The passage 102 is unblocked because the stem 74 has moved up. Thus, the pressure fluid now rushes through both passages and 102, so that the pressure in chamber 38 is raised up substantially to the supply pressure.

In the pile driver system 20A of FIG. 20, the operator starts the piston weight 24 in the same way as for systems 20 and 20B, namely, by suddenly starting the flow of pressure fluid through the line 94. The passage 100 allows pressure fluid to surge into the storage chamber 38, and it flows up through the open valve 40. This surge of pressure fluidup through the open valve 40 suddenly pushes the piston weight 24 upwardly.

The sudden upward push on the piston weight 24(in

system

20, 20A or 20B) causes it to rise up, as shown in FIG. 13, to the point where the outlet ports 106 are unblocked. The expanded pressure fluid in the bounce chamber 34 is released through ports 106, allowing the 7 is greater than the first one, because the pressure in storage chamber 38 has become more nearly equal to supply pressure. Thus, the piston weight 24 is accelerated more and rises up, as shown in FIG. 13, further be yond the ports 106.

The expanded fluid is again released and the piston weight falls down again, as shown in FIG. 9. It is descending faster than the first time, and it opens the valve, as shown in FIG.'10, this time the valve being opened wider and longer. than the first time, because the piston weight descends farther. Accordingly, even more pressure fluid is injected to hurl the piston weight up farther than the second time, and so forth.

After about three to six cycles, the piston weight 24 reaches its full amplitude for driving the pile. As shown in FIGS. 9, 10, ll, l2, l3 and 14, when the piston weight has reached its full amplitude, in each cycle it descends so far that the plunger head 93 is driven down to block the port 62, as shown in FIG. 11.

The following is an explanation of a typical operating cycle: FIG. 9 shows the piston weight 24 descending. It is below the level of the outlet ports 106, and so any residual pressure fluid in the bounce chamber 34 is being compressed. This compression begins to decelerate the piston weight, and the compression also begins to exert a downward thrust on the cylinder bottom assembly 26, thereby beginning to thrust down upon the pile 28. In this way, the bottom assembly 26, coupling 32, and pile 28 are prestressed to remove all play therein.

FIG. 3 shows the piston weight assembly at the moment it comes in contact with the head 93 of the actuator 91.

FIG; 10 shows the valve fully opened by depression of the actuator. The pressure fluid is being injected through the port 62 into the bounce chamber. The resultant sudden increase in pressure beneath the piston weight 24 increases its decelerationand produces a powerful down thrust on the pile 28, as indicated in FIG. 10 by the twin arrows on the adapter 32.

FIG. 11 shows the injected port 62 closed by the fluid trapping head means 93. The injection pressure fluid and any residual pressure fluid remaining in the bounce chamber from the previous cycle are now trapped by blockage of the port 62. Accordingly, the descending piston weight produces a tremendous compression of the trapped fluid, as indicated by the compression arrows C (FIG. 11) and still greater compression C (FIG. 12).

The increasing compression pressures (C and C) produce a tremendous and enduring downward thrust on the pile, as shown by the twin arrows in FIGS. 11 and 12 near the coupling 30. A resilient compressed fluid cushioned bouncing action occurs, i.e. the piston weight is completely decelerated and is re-accelerated upwardly, as shown in FIG. 13.

The re-acceleration upwardly, such as occurs between FIGS. 12 and 13, produces a continuing powerful downward thrust on the-pile until the ports 106 are uncovered.

Thus, there-is a downward thrust occurring during the operation shown in FIGS. 9, 3, 10, 11 and 12 and during the re-acceleration occurring between the positions shown in FIGS. 12 and 13.

When a deep head plug 230A is being used, as shown in FIG. 14, then atmospheric air is trapped above the piston weight 24, so as to produce a double-acting piston effect. The downward push of the trapped air on thepiston, which has risen up near the head plug 230A, is indicated in F IG. 14 by the plural arrows beneath the head plug.

It is noted that a two-stage trapping action of compressible'fluid occurs beneath the descending piston in the systems and 20B. In FIG. 9 pressure fluid is trapped beneath the descending piston because ports 106 and valve 40 areclosed. After the driving pressure fluid has been injected (FIG. 10), a second trapping ac tion occurs as indicated at C and C in FIGS. 11 and 12 because the injector port 62 is closed.

It is noted that in the pile extraction, the piston weight 24 is started to reciprocate by first slacking the cable 236 (FIG. 17), so that the pile driver 20 is resting down upon the pile, then the flow of pressure fluid is turned on in the line 94 to start the piston weight up and down. As soon as it is reciprocating at full amplitude, the upward pull is applied to cable 236 to begin extraction.

In all of the systems shown, the reciprocation of the piston weight 24 is stopped by shutting off the flow of pressure fluid through the hose line 94.

The

pile driver system

20A or 208 can also be used for pile extraction in the same general mariner as the pile driver system 20.

Advantageously, the operator can increase the time duration of each fluid-cushioned powerful driving thrust and decrease the peak force occurring during each driving thrust by increasing the extent of trapping of pressurized fluid by the trapping means 93 (FIG. 3), and vice versa. By increasing the height of trapping means 93, port 62 becomes blocked when piston 24 is at a larger predetermined distance from the bottom assembly 26, thus increasing the extent of trapping, and vice versa. For convenience, if desired, detachable inter-changeable heads 93 can be provided which are attached by screw means to the actuator 91.

I claim:

1. Pile driver apparatus for driving a pile into the earth comprising a cylinder wall defining a cylinder, a massive piston weight movable up and down within said cylinder, a bottom assembly associated with said cylinder wall and positioned below said piston weight adapted to be coupled in thrust transmitting relationship to the pile to be driven, said piston weight and cylinder bottom assembly defining a bounce chamber between them, compressible pressurized fluid storage chamber means adapted to communicate with said bounce chamber, a valve for blocking communication between said storage chamber and said bounce chamber, input means for feeding pressurized fluid into said storage chamber from a remote source of supply, and means for opening said valve for injecting pressurized fluid from said storage chamber into said bounce chamcylinder.

2. Pile driver apparatus for driving a pile into the earth, as claimed in claim 1, in which said cylinder bottom assembly includes said compressible pressurized fluid storage chamber means. 3. Pile driver apparatus for driving a'pile into the earth, as claimed in claim 1, in which said means for opening said 'valve is actuated by the descending piston weight.

4. Pile driver apparatus for driving a pile into the earth, as claimed in claim 1, including trapping means for trapping pressurized fluid in the bounce chamber beneath the descending piston weight for producing pressurized fluid cushioned bouncing action of the piston weight providing a powerful downward thrust upon said cylinder bottom assembly upon each bounce of the piston weight to be transmitted to the pile for driving it into the earth.

5. Pile driver apparatus for driving a pile into the earth, as claimed in claim 1, in which said cylinder bottom assembly includes a second piston movable up and down with respect to the cylinder wall and adapted to be coupled to the pile in thrust transmitting relationship.

6. Pile driver apparatus for driving a pile into the earth as claimed in claim 1, in which said cylinder bottom assembly includes an annular flange at the lower end thereof, and a clamp ring for encircling said annular flange for coupling the cylinder bottom assembly to the pile in thrust transmitting relationship.

7. Pile driver apparatus for driving a pile into the earth as claimed in'claim 1, in which an outlet port is provided in the cylinder wall for releasing expanded pressurized fluid from the bounce chamber, and a muffler enclosing the outlet port.

8. Pile driver apparatus for driving a pile into the earth as claimed in claim .7, in which said muffler includes means for separating lubricating oil from the pressurized fluid.

9. Pile driver apparatus for driving a pile into the earth as claimed in claim 8, in which a lubricating oil l7 reservoir is associated with said muffler, and a selfcontained lubrication system associated with said oil reservoir, said lubrication system being actuated by the pressure changes in said bounce chamber.

10. Pile driving apparatus comprising a piston weight of large mass adapted to reciprocate up and down within a cylinder, said cylinder having a second piston adapted to reciprocate up and down within the lower end of the cylinder and adapted to be coupled in thrust transmitting relationship to the pile being driven, said piston weight and second piston defining a bounce chamber between them, said second piston having a pressure fluid inlet passage, a pressure fluid storage chamber in said second piston supplied by said passage, and a valve adapted to be opened to release the pressure fluid from the storage chamber into the bounce chamber when the piston weight descends and approaches the second piston.

l1. Pile driving apparatus as claimed in claim 10, in which trapping means are provided for trapping the pressure fluid in the bounce chamber after the pressure fluid has been released from the storage chamber into the bounce chamber.

l2. Pile driving apparatus as claimed in claim 11, in which said trapping means are included in the valve for blocking off communication between the bounce chamber and the storage chamber.

13. Pile driving apparatus as claimed in claim 10, in which said valve includes an actuator extending upwardly adapted to be engaged by the descending piston weight for opening said valve to release the pressur fluid.

14. Pile driving apparatus as claimed in claim 13, in which said second piston has a port surrounding said actuator for providing. communication between the storage chamber and the bounce chamber when the valve is opened, and an enlarged head on said actuator adapted to be depressed into said port for blocking said port for trapping the pressure fluid in said bounce chamber beneath the descending piston weight.

15. Pile driving apparatus as claimed in claim 13, in which said valve includes a valve member which is depressed by said actuator, said storage chamber and valve member having interfitting parts providing a cushion of pressure fluid preventing the valve member from striking bottom when it has been depressed.

l6. Pile driver apparatus comprising a cylinder wall defining a cylinder, a massive piston weight movable up and down within said cylinder, a bottom assembly associated with said cylinder wall and positioned below said piston weight, said piston weight and cylinder bottom assembly defining a bounce chamber between them, said cylinder bottom assembly including means defining a storage chamber for storage of pressurized fluid, said storage chamber having a port communicating 18' with said bounce chamber, said storage chamber having a valve guide with a vertical bore, a valve member having a stem extending down into said bore, said valve .rnember being movable up and down and when in its upper position said valve member blocking said port, said cylinder bottom assembly having an input passage for pressurized fluid communicating with the bore of said valve guide and said valve guide having an opening providing communication between said bore and said storage chamber, and said valve member being moved down by the descending piston weight for opening said port to inject pressurized fluid into said bounce chamber.

17. Pile driver apparatus as claimed in claim 16, in which said valve guide has an upper and lower opening each providing communication between the bore and the storage chamber, the upper opening being larger than the lower one, and said valve stem blocking the upper opening when the valve member is moved down.

18. Pile driver apparatus comprising a cylinder wall defining a cylinder, a massive piston weight movable up and down within said cylinder, a bottom assembly associated with said cylinder wall and positioned below said piston weight, said piston weight and cylinder bottom assembly defining a bounce chamber below said piston weight and above said bottom assembly, said cylinder bottom assembly including means defining a storage chamber for storage of pressurized fluid within said bottom assembly, said storage chamber having a port communicating between the top of said storage chamber and said bounce chamber, a valve member associated with said port, said valve member being movable up and down and when in its upper position said valve member blocking said port, said cylinder bottom assembly having an input passage for feeding compressible pressurized fluid intosaid storage chamber, actuatormeans extending into said bounce chamber for moving said valve member down when the piston weight is descending for opening said port to inject compressible pressurized fluid from said storage cham-- ber up into said bounce chamber beneath the descending piston weight to bounce the piston weight upwardly, and said cylinder wall having outlet port means for releasing the expanded compressible pressurized fluid from the cylinder after the piston weight has bounced upwardly to repeat the cycle, whereby the piston weight quietly bounces up and down within said cylinder. I

19. Pile driver apparatus as claimed in claim 18, in which means are provided for blocking said port after compressible pressurized fluid has been injected into the bounce chamber for trapping the compressible pressurized fluid beneath the descending piston weight.

Claims

1. Pile driver apparatus for driving a pile into the earth comprising a cylinder wall defining a cylinder, a massive piston weight movable up and down within said cylinder, a bottom assembly associated with said cylinder wall and positioned below said piston weight adapted to be coupled in thrust transmitting relationship to the pile to be driven, said piston weight and cylinder bottom assembly defining a bounce chamber between them, compressible pressurized fluid storage chamber means adapted to communicate with said bounce chamber, a valve for blocking communication between said storage chamber and said bounce chamber, input means for feeding pressurized fluid into said storage chamber from a remote source of supply, and means for opening said valve for injecting pressurized fluid from said storage chamber into said bounce chaMber when the piston weight is descending withing the cylinder.

2. Pile driver apparatus for driving a pile into the earth, as claimed in claim 1, in which said cylinder bottom assembly includes said compressible pressurized fluid storage chamber means.

3. Pile driver apparatus for driving a pile into the earth, as claimed in claim 1, in which said means for opening said valve is actuated by the descending piston weight.

7. Pile driver apparatus for driving a pile into the earth as claimed in claim 1, in which an outlet port is provided in the cylinder wall for releasing expanded pressurized fluid from the bounce chamber, and a muffler enclosing the outlet port.

8. Pile driver apparatus for driving a pile into the earth as claimed in claim 7, in which said muffler includes means for separating lubricating oil from the pressurized fluid.

9. Pile driver apparatus for driving a pile into the earth as claimed in claim 8, in which a lubricating oil reservoir is associated with said muffler, and a self-contained lubrication system associated with said oil reservoir, said lubrication system being actuated by the pressure changes in said bounce chamber.

11. Pile driving apparatus as claimed in claim 10, in which trapping means are provided for trapping the pressure fluid in the bounce chamber after the pressure fluid has been released from the storage chamber into the bounce chamber.

12. Pile driving apparatus as claimed in claim 11, in which said trapping means are included in the valve for blocking off communication between the bounce chamber and the storage chamber.

13. Pile driving apparatus as claimed in claim 10, in which said valve includes an actuator extending upwardly adapted to be engaged by the descending piston weight for opening said valve to release the pressure fluid.

14. Pile driving apparatus as claimed in claim 13, in which said second piston has a port surrounding said actuator for providing communication between the storage chamber and the bounce chamber when the valve is opened, and an enlarged head on said actuator adapted to be depressed into said port for blocking said port for trapping the pressure fluid in said bounce chamber beneath the descending piston weight.

16. Pile driver apparatus comprising a cylinder wall defining a cylinder, a massive piston weight movable up and down within said cylinder, a bottom assembly associated with said cylinder wall and positioned below said piston weight, said piston weight and cylinder bottom assembly defining a bounce chamber between them, said cylinder bottom assembly including means defining a storage chamber for storage of pressurized fluid, said storage chamber having a port communicating with said bounce chamber, said storage chamber having a valve guide with a vertical bore, a valve member having a stem extending down into said bore, said valve member being movable up and down and when in its upper position said valve member blocking said port, said cylinder bottom assembly having an input passage for pressurized fluid communicating with the bore of said valve guide and said valve guide having an opening providing communication between said bore and said storage chamber, and said valve member being moved down by the descending piston weight for opening said port to inject pressurized fluid into said bounce chamber.

18. Pile driver apparatus comprising a cylinder wall defining a cylinder, a massive piston weight movable up and down within said cylinder, a bottom assembly associated with said cylinder wall and positioned below said piston weight, said piston weight and cylinder bottom assembly defining a bounce chamber below said piston weight and above said bottom assembly, said cylinder bottom assembly including means defining a storage chamber for storage of pressurized fluid within said bottom assembly, said storage chamber having a port communicating between the top of said storage chamber and said bounce chamber, a valve member associated with said port, said valve member being movable up and down and when in its upper position said valve member blocking said port, said cylinder bottom assembly having an input passage for feeding compressible pressurized fluid into said storage chamber, actuator means extending into said bounce chamber for moving said valve member down when the piston weight is descending for opening said port to inject compressible pressurized fluid from said storage chamber up into said bounce chamber beneath the descending piston weight to bounce the piston weight upwardly, and said cylinder wall having outlet port means for releasing the expanded compressible pressurized fluid from the cylinder after the piston weight has bounced upwardly to repeat the cycle, whereby the piston weight quietly bounces up and down within said cylinder.