US2676464A - Hydraulic impact pulsator transmission system - Google Patents

Description

April 27, 1954 C. F. WARREN 4 HYDRAULIC IMPACT PULSATOR TRANSMI Filed April 12. 1946 SSION SYSTEM 4 Sheets-Shea?. l

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April 27, 1954 c. F. WARREN I HYDRAULIC IMPACT PULSATOR TRANSMISSION SYSTEM Filed April 12, 1946 NVENTOR. Czrleslrrem *r4 m A April 27, 1954 c. F. WARREN 2,676,464

HYDRAULIC IMPACT PULsAToR TRANSMISSION SYSTEM Filed April l2, 1946 4 Sheets-Sheet 3 IN V EN TOR.

April 27, 1954' C, F, WARRENV 2,676,464

HYDRAULIC IMPACT PULSATOR TRANSMISSION SYSTEM Filed April 12, 1946 4 Sheets-5h96?. 4

157 j 58 *62 \61 1 f7/@ffy 5%/ l 53 253'/ INVENTOR. @arleslarrem Patented Apr. 27, 1954 HYDRAULIC IMPACT PULSATOR TRANS- MISSION SYSTEM Charles F. Warren, Milwaukee, Wis., assignor, by mesne assignments, to Charles F. Warren, J r.

Application April 12, 1946, Serial No. 661,542

1 The invention relatesA generally to hydraulic impact transmission systems and more. particularly to a .system adapted to transmit impacts by means of a reciprocating column of fluid.4 It is the general object of the invention to provide a new and improved system of this character.

Another object is to provide a hydraulic impact transmission system for use with portable impact tools; and particularly one having a conduit between an impact producing unit and an impact tool unit, means in the impact unit for filling the conduit with a fluid (as for example, oil or other suitable liquid) and for maintaining a column of iiuid in the conduit under static pressure, means for imparting rapid reciprocating movement to the rigid column so formed, and means at the impact tool unit end of the conduit forming a restricted return outlet for excess fluid supplied to the conduit. A further object is toprovide such a system with manually operable means at the impact tool unit forenlarging the return outlet for the fluid so as to relieve the pressure on the column and stop the operation of the tool.

Another object is to provide an impact transmission system with'an impact producing unit, an impact tool unit and pressure fluid supply and return conduits connecting the impact unit with the impact tool unit, together with control means carried on the tool unit for starting and stopping the operation of the tool when the impact unit is in operation.

Another object is to provide a new and improved impact tool unit for transmission system. f

A further object is to provide a new and improved hydraulic impact transmission system embodying a reciprocable rigid column of uid, means for reciprocatingthe column, means connected to one end of the column for supplying fluid thereto at Aa rate'- in excess ofthe leakage therefrom, and means at the other end of the column for controlling the discharge of excessfluid therefrom. f

Other objects and advantages will become readily apparent from the following detailed description taken in connection with the accompanying drawings in which:

Fig. 1 is a perspective View of a preferred form of the invention. Fig. la is a perspective view thereof on a reduced scale with two impact tool units. Fig. 2 is a vertical section approximately along the line 2--2 of Fig.3 of the pumping unit thereof. Fig. 3 is a planl.` section along the line 3-3-of Fig..2. Figav is a vertical section on -13 claims. (cl. so-54.5)

a reduced scale along the line 4-4 of Fig. 2. Fig. 5 is a vertical central section through the impact tool unit. Fig. 5a is an enlarged fragmentary view of a portion of Fig. 5. Fig. 6 is a fragmentary section along the line E-S of Fig. 5. Fig. 7 is a similar fragmentary section with the control valve in an alternative position.

While my invention is susceptible of embodiment in many different forms, I have shown in the drawings and will herein describe in detail one such embodiment, with the understanding that the present disclosure is to be considered as an exemplication of the principles of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will be vpointed out in the appended claims.

In the form selected for purposes of disclosure this invention is embodied in a hydraulically actuated impact `tool system comprising generally a pumping or impact producing unit A (Fig. 1), an impact tool B, a supply conduit C connecting the pumping unit to the impact tool for conducting a fluid (such as oil) under pressure to operate the impact tool and a return conduit D for returning the operating iiuid to the pumping unit. As shown in Fig. 1a a pair of impact tool units B are connected to an impact producing unit-A, the unit A and a drive motor E therefor being mounted on a common frame F. As shown, a belt G runs from a pulley on the motor to a pulley I-I on the drive shaft of the unit A. Y

Impact tools of the character to which this invention relates are in the nature of hammers, drills and tampers, which are similar in function to corresponding pneumatically driven tools.

However, such tools of the pneumatic type require the provision of an air 4compressor unit-accompanied by an internal combustion motor or other primeimover lof substantial power, whereas the combination of .an impact unit or pump and an impact tool directly connected to the pump by means of .a flexible conduit which connes a continuous and rigid column of fluid under pressure extending from the pump to the tool, constitutes a much more efficient mechanism and employs only a fraction of the power of the pneumatic-system for driving the pump and operating the. tool. The present invention is an improvement in hydraulic impact transmitting systems of the type embodying a` rigid reciprocable column ofv oil (or otherliquid; and constitutes an improvement in the system of Patent No.. Re. 122,122, is-

concentric with the axis of a drive shaft 5. This shaft extends through a hollow boss 6 in one side wall of the housing, and the boss 6 provides a pocket or recess 6at which seats the roller bearing 1 for the shaft together with a packing# element 8. A circular opening 9 in the opposite side wall of the housing is large enough to permit insertion or Withdrawal of the shaft 5 with its driving eccentrics I0, I6 together with thebearing assembly; and this opening 9 is closed by a cover plate II which includes an inwardly open pocket or recess Ila to support a roller bearing l2. for the inner end of the shaft 5. Each of the eccentrics I carries a ring I3 confined between a flange Ii]a and a retainer ring II)b with interposed bearing rollers I4, so that the eccentric may turn freely within the ring I3. Thus in the process of assembly, the shaft5, with its bearings 1 and I2 in place and with its eccentrics I3 tted with their rings I4, may be inserted as a unit through the opening 9, and its mounting in the housing will be completedV by application of the cover plate |,I' and securement thereof by means of fastening screws I5. It may beV understood that the projecting end of the shaft 5 will be fitted with any suitable pulley or gear for operative connection with a prime mover such as an electric motor or internal Vcombustion engine.

-The pumping device proper is contained in a cylinder block or casting I6 having a circular inner end portion I1 which nts snugly into a circular opening I8 in a 'diaphragm orr partition wall I5 extending across the housing I, as seen in Figs. 2 and 3. This provides support for the inner end of the casting I6v and locates the closed ends of the pistons 20, in operative relation to the rings I3 on the driving eccentrics I0, I6. At its outer end the casting I6 -is formed with a flange 2| having a circular shoulder 22 which fits into a circular opening 23 in the end wall 24 of the housing I. The pumping device is secured in place by screws 25 extending through said flange 2| and into the end wall 24` adjacent its opening 23. Thusthe insertion of the unit I6, with the pistons 2|] and other operative parts already assembled in it, completes theassembly of the pumping device. i

Each. of the pistons 2.0 is hollow and. open at one end to accommodate a springV 26whichreacts against the end wall. of` a chamber 21. formedr in the casting I6; and each pistonV includes a larger portion 20a' anda slightly smaller.v portion 26h, the casting I6 being. formed with-corresponding bores I6a and I6b in which thesel portions of the piston reciprocate respectively. The bore I6b communicates directly with the chamber'21, and said chamber terminates in a threaded opening into which the terminal 28 of the flexible conduit or hose C is secured, as seen in Fig. 2. Thus, when the hollow piston 20 and chamber 2.1 and conduit C are filled with hydraulic fluid under pressure, the reciprocatory movements of the piston are transmitted longitudinally by the rigid column of fluid tov theimpact tool B, as herein after more fully described. f

The lower portion of the housing I serves as a reservoir for the fluid which will be maintained always at a level considerably above the lower end of the supply pipe 30 which depends from the pump casting I6 and is secured therein by a gland 3| which also supports the valve seat 32 for a ball check valve 33 normally seated by its spring 34. The check valve 33 controls access to an annular passage 35 formed in the casting I6 at the junction of the bores I6a and |61. The shoulder 2|)c of the piston 20 which defines the outer end of the larger portion 2|)EL operates as a secondary piston head as said larger portion 2Ila of the piston reciprocates in the bore |691 As the piston moves toward the axis of the shaft 5, the suction or partial vacuum operating in the annular passage 35 lifts the check valve 33 from its seat and tends to draw fluid. through the supply pipe 30 into the passage 35 and into the bore I6EL adjacent the shoulder 2|)cv ofthe piston. Then, upon the4 return stroke ofv thepiston, theshoulder 20 forces the fluid past a second check valve 36 and through a passage 31 which leads into the chamber 21.

In the construction herein illustrated, with the two eccentrics I6, I0 set 180 apart on the shaft 5, the mechanism is in the nature of a duplex pump with the two pistons 20, 20 operating alternately and thus transmitting separate impulses through two conduitsV C which are connected respectively to the two chambers 21.

In operation it is most convenient to use oil for theimpact transmitting medium and to employ the same oil for lubrication of the mechanism; accordingly, the web or partition I9 is formed with an opening in its lower portion which affords communication between the space in the housing directly under the drive shaft 5 and the spacevextending below the pump cylinder casting I6. Preferably this opening is coveredl by 'a screen. A connection device I|5 for the return conduit D is removable from the top wall above the shaft 5 for adding oil as required. The iiuid returned through the conduit D is discharged onto the operating parts to lubricate them. Although the feed tubes 30 and check valve assemblies 3|, 32, 33, 34 can be originally attached to the cylinder casting I6 and entered with it through the opening 23, it may be desirable to remove these parts occasionally without withdrawing the cylinder units and to facilitate this the bottom wall of thel housing is formed with threaded openings directly below the tubes 30, these openings being normally closed by screw plugs |53, as shown in Fig. 2.

Asy illustrated in the drawings, the impact tool B (Figs. l and 5 to '1) comprises a tubular barrel having a cylinder 5| formed in the upper portion thereof, a bore 5,2' in the middle portion thereof, and a. slightly larger bore 53 inithe lower. end thereof. A head member54 isscrewthreaded to the upper end of the'barrel andr has handleapo tions 55 and 56 adapted tov facilitateuse ofthe tool. At its lower end, a bushing 51 is pressed into the bore 53 and has a hexagonal opening 58 therethrough in' which the shank 59 of a ltool 60 is slidably guided. A tool retainer. is shown as comprising a collar 6| screw threaded on to the barrelat 62 and a cup-shaped retainingv member 63. The cup-shaped member has an opening 64 through which the `tool extends and is formed at its upper end 65 to interengage a beveled por tion 66.0n the collar '6 I.

Forxstriking or imparting `impacts to the.. tool a plunger orimpact member; 10 sreciprocably f s mounted in the bore 52 of the barrel and is formed with a longitudinally extending bore 1|. Fluid supplied to the impact tool unit B throughthe conduit C passes through a connection 'i2 to a bore 13 in the head member 54 and thence through a horizontal bore 14 to a vertical bore 15 posithe end surface 11 of the bore 1| to move the' impact member downwardly through a stroke and to cause said member to strike the upper end of the tool shank 59. The flow of fluid to the impact member 10 is controlled by a valve Si! here- 4inafter more fully described.

Although the tube 16 :nay be secured rigidly. to

.the head member 64 and have a sliding and sealing t in the bore 1|, in the form shown a flexible ball and socket joint 8| is provided between the upper end of the tube and the head member. 54 and a ball and socket joint 82 is provided between the upper end of the impact member 10 and the lower portion of the tube 16. The upper joint 8| comprises a ball member 83 sealed tightly on` a reduced portion 84 of the tube 16, a socket formed .partly on the head member 54 and partly on a collar 85 which is screw threaded a1; 86 into a f ,recess in the head member, and an annular seal- .ingring 81 of resilient material such as rubber or synthetic rubber positioned in an annular recess S8 formed by the head member and collarv. r:The lower joint 82 comprises a ball member 90 having a sliding t on the tube 16, a socket formed .partly in the piston member 10 and partly in the collar member 9| screw threaded at 92 into a recess in the piston member, and a sealing ringl 93 positioned in a recess 94 in the piston member. 4.As shown more clearly in Fig. 5a, the sealing ring Vis positioned in the upper portion of the recess I.94 and is slightly compressed between the right 'hand surface of the recess and the surface of the -ball member 99. The surface95 against which the collar member 9| seats is preferably in the i same plane as the center of the ball member 90. If the fluid under pressure in the -tube 16 has a tendency to pass between said tube and the bore `1| of the impact member 10and leak across the '.the spherical joint between ther lower portion of f the ball J. and the socket. The uppcrballfand .socket joint 8| is similarly arranged so thatthe ljoint between .the collar and the headmember -54 is!V on ythe low pressure side of Athe sealing ring .81. These ball and socket joints are more fully Adisclosed and claimed in my co-pending applica- ,tion Serial No. 595,016, .led May 21, 1945,..on 'Flexible Pipe Joints, now `Patent No. 2,554,938,

dated August 21, 1951.

By providing flexible joints intermediate the Ytube 16 and the parts 54 and 10, it is possible to obtain smooth and efficient operation even though the bores 15 and 1| are not in alinement.

The impact .member 1li may-be returned upwardly through the return stroke of its 'movement by resilient means acting upwardly thereon; As

Yport H3 in the head member.

shown herein, this means comprises an air cushion created in a chamber ||J| in the bore 5l of the barrel below a piston 96 which is formed integrally with the upper end of the impact member 10 and slides in the bore 5|. The barrel is provided with a series of horizontally extending ports 91, 98, 99, |90, in the side wall thereof and which communicate with the bore 5| to admit air therethrough during the upward vstroke of the piston 95. During the downward stroke of the piston, a, quantity of air is trapped in the chamber |0| and is compressed during the final downward movement of the impact member 19 to form the air cushion. An impact tool of this type ismore fully disclosed and claimed in my co-pending application Serial No. 576,767, filed February 8,1945, entitled Hydraulic Impact Tool, now Patent No. 2,624,177, dated January 6, 1953.

-In the preferred form disclosed herein, my invention differs in part from the hydraulic impact tool system of' U. S. Letters Patent, Re. 22,122 of June 16, 1942, andthat of the co-pending application of Charles F. Warren and Karl F. Kuehn, Serial No. 442,730, filed May 13, 1942, now Patent No. 2,397,174, dated March 26, 1946, by providing in the head member 54 of the impact tool unit, a control for the output fluid pressure 'of the pumping unit A. As illustrated herein, this control comprises the rotary valve 80 located in Athe bore 14 and provided with an operating handle projecting downwardly from the handle 55 through a slot |06 therein. Preferably, seal rings |91 are provided in the rotary valve member to prevent leakage through the slot |06, and a port |98 extends longitudinally through the valve member to equalize the pressure on both ends thereof. A plug I 09 closes the left hand end (Fig. 5) of the bore 14. The right handend. of the valve member has a bore ||0 therein and a recess cut in the side wall thereof so. that an edge ||2 of the recess controls a fluid return The port ||3 communicates with a fitting I 4 (Fig. 1) to which the adjacent end of the fluid return conduit .D is connected. The other end of the return ,conduit is connected to the tting |15 secured .in a threaded bore IIS (Fig. 2) in the upper wallof nthe housing of the pumping unit, so that Voil returned to the pumping unit from the tool is discharged on to the .projecting ends of -the pistons 20, the eccentric devices onthe drive .shaft '5 and the shaft bearings, In this way, theoplerating parts are continuously lubricated.

' m operating the form of the invention. illus- .trated in the drawings, it is' contemplated that the drive shaft 5 of the pumping unit will" be idriven from a suitable prime mover such as an electric motor E by means of a belt G operating on a pulley H on the shaft 5 and which may be started when the system is to be used and stopped ,when the system is to be shut down completely linders,` the power strokes being produced by the 'eccentric devices on the shaft and thev return strokes by the coiled springs 25 (Fig. 2). During such reciprocation of the pistons, the secondary pistons 29 function as makeup pumps'to draw f oil from the reservoir in the bottom of the housing chamber, through the tubes 30 and past the check valves 33 and to force such fluid past the check valves 36 and through the passages 31 into oil the aikeup. pumps 'fonid'by tige secondary pistons. 201i.' operate tiontiruouslyto'supply'fluid to"L the hydrai'ilio,V c'olur'nns, formed between Athe pistons 2n andthe tool imp'gictiiierribens` lof'frhis; 'is purnped atnautite iii` excess. of EEK-@56' fro thesysternl vIn. a. system utilizing` Conduit of three-.openers ip'oh' internal" dio'rnetoif; a; rate of eleven )gallons pei\l,1`o11`r. hes resulted' in" suol' cassini, 'opertipnf'ltlo gli 'the quantity. moll dypvad-p. f. Rreferring` 'rioxv to. onel System. with the hyf druli' eoliimi formed in the oonduit'C between @"fiisftoi'of 'the 'puin ing and one impact tool'unit Bg'uie control for. tne'bpjereuqn of thatimpaet i991 Wm? is tht. Vail/fe 80.! When 'hSYafll-elg its 'openpo's'ition e's'shoyvn inA Figs. 5 and@ the i'tiip til ltfiS@ Wide operi'ndperinfits 'oualii Qty gf n ie, eq 1t@ um'pumped'by thejmk'ef op piiiipy"to iotllrn 'freelyto the conduit' D- Upd'. such auditions 'the' fluid in the hydraulic @nime between' the" pistons" zo V`@ma 1n, npr undefsufcientpressur'e to'actua'lte the inpgict nie per '70. The impact toolB is thereforeidle.

impact'nlember 1n' on'the'tool 'Goulay be cgQn- .polled by the velve by moving the valve Lto Y'sirilolis poS'itoS .iiltmedlto 4the Wide ,operi am msgid conduit) T somo nop piston. epd. the,"re.1oitivo oxo asoffthepufii espn. en be... "gy loooting o. pressure oontrol volvo ln the handle of "tlejinipact tool', afdvantgesjqruein' a'ddition'to the convenient control A'for ein opfe tor! Since, an impact topis 'generally 'use rbout 50% of the vtime the purnping'unt'isin operation, the continued' circulation ot" fitti@ through `the' supply'and return' nduit'sl when the` tool lo potV in'oporotion'. lfujnotiflJi-.is tooooi tht fluid and 'thereby keepjthe temperturefof the conduits 'and other. 'parts yliicncohpe uit; yi drillilc. COt-im ai? 3. minimum Ifx'dlllig. J9 i tior'r of -che tool unit the 'Conduit should' vibratlonai'movomopts. duo toy tho" rooiprooe'tioii of thev rigid hydraulic column, such mov ments oi tho Conduit Stops When, tiio. tool lliiit i. oli* erati've, thuss'avng; Wear'end teer on'the 69p.- duit.v The rigidity of 'the olurrin is built Cgi d'estroyedl] 'upderitho control 'offtho voli/80 'at the impaot tool unit'end of the syster'naniger'f orally takes'plaoe' after thej'impeot' pro munism..operati0n. ""When e single ilnpact tool unit is used with ein impaovt producing unit of tlie type herein dis; olos'd (havingtwo pump.L pistons 20), m preferably provided to bypass theflfuil i system Whiohis not in use. As show'A v such a bypass moans. comprises a port l 2l! loodiir oootionel from lchamber 2 to a, valve 'port vl2l| Wliic Charges through a paSpege/lllf itQ tho in the housing I. A 'valve [23 controls th l2! and is adjustable from exterioijly o "i th ingby means of a. handQl/ 124. Tn iS Closed lasshown) when 'thesy'jst'om 1 end is opened to bypess fluid fronfi tl'i'e cbj 2? "n .AH. `I)

'I claim;

1- A 'hydrolilip impayot transmitting ,system ooipprisine.' in oombina'tori' "floxiblo' .oQ 'doit oidaptedto" contain a"' c.1l1rpn'of fluid. irppat' producing upit connected tooe'epd 'olf .tlgg foopploit ond Comprising moons for 'imparting' foar'- Wad' strokes' to a roolprjooable 'rigidV ,oolupipi'plf iid therein', an impact tool unit 'onnet to theother end of said "conduit andeornp pioppo includ-lne an impaot'mo'r'pbor lrooiprv .ilo 'tho other ,epd .of seid 'Conduit by. seid oo'llimn of fluid, 'means/"loir Supplyine'make-up' .flu'lsl .to said' oonduit'in a yqueritityjsubstemtigtlly'in ex` ss 'ofthe leakage' therefromi pnd'yalye @tithe ngbeen' i001 unit ,erle of 'coiduil @been Control en 'orlffloe throueh'whoh the; 9X inekeup uid'esoapes'from the'conduirt, ainld'h return" 'Conduit forjcond-ucting'suh excess ineke; .up fluid back to the make-11p uid'supply ipe 2J A' hydreiplip impact transmitting comprising in combination, ainexble "ppgluit colpm'pf liuidtherep," en 'imfpeot producing .uniti'go'onnected to 'oneendotthe conduit 'and compiler* means ierimnarting .for 't's'aidcolump' pif u'ilianlmpot'too .uniti j 'neared tothe other' end ofsaid gondel; and. com; 'prising means" including an "im'pap'f driven in the other end of seid oonduiI Yy column' of uid, means `for" imparting 'i turn strokes to 'said'column, means for suppIyinguid to Seid ,conduit in a quantity"Substantially*in excess "of 'the 'leakage therefrom; and 'a "valve y lt the impact tool unit 'end ofthe :conduit 9pr u' to' control an' orifice through `wvllioh` thefex fluid escapes' from the conduit.4 3 A" hydraulic' impactransmit tiiig .S Stom ,d

to contain a column of fluid, a rst closure reciprocably mounted on one end of the conduit and sealing that end of the iluid column, an impact producing unit connected to said end of the conduit and comprising means for actuating said closure to impart strokes thereto, an impact tool unit connected to the other end-of said 4conduit and including an impact member reciprocable in the other end of said conduit and sealing the.

other end of the uid column, means for supplying make-up fluid to said conduit at a rate in excess of the leakage therefrom to form a rigid column of iiuid between said closures, valve controlled means at the impact tool unit end of-the conduit operable to control the size of an orifice through which the excess make-up fluid escapes from the conduit, and a return conduit for conducting such excess make-up fluid back to the make-up fluid supply means.

4. A hydraulic impact transmitting system comprising, in combination, a conduit, a first closure reciprocably mounted in one end of the conduit, a relatively stationary impact producing unit connected to said end of the conduit and comprising means for actuating said closure to impart strokes thereto, means for driving said actuating means, a portable impact tool -unit connected to the other end of said conduit and including an impact member forming a closure reciprocable in the other end of said conduit, means in said impact producing unit for supplying fluid to said conduit at a rate in excess of the leakage therefrom to fillthe conduit and form a rigid column oi fluid between said closures, valve controlled means at the impact tool unit end of the conduit operable to control an oriiice through which the excess nuid escapes from the conduit, and a return conduit for conducting such excess make-up fluid back to the iluid supply means.

5. A hydraulic impact transmitting system comprising, in combination, a conduit, a rst closure in one end of the conduit and reciprocable between spaced positions, a second closure in the other end of the conduit, means for supplying fluid to said conduit at one end thereof in a quantity in excess of the leakage therefrom when the system is in operation, means for reciprocating said closures and the column of fluid therebetween as an integral unit, a second conduit extending from said rst conduit at a point adi jacent said second closure to said fluid supply means for returning excess iiuid to the supply means, and valve means located adjacent the junction of said conduits for controlling the passage of fluid from the iirst conduit to the second conduit.

6. A hydraulic impact transmitting system comprising, in combination, a flexible conduit, a first closure reciprocable in one end of the conduit, an impact member reciprocable in the other end of the conduit, a rigid reciprocable iiuid column occupying said conduit and having its ends in direct contact with said closure and impact member and operable to transmit motion therebetween, means for imparting strokes in one direction to said column comprising an actuating device for said closure, means for imparting return strokes to said column operable on said impact member, means connected to the closure end of said conduit operable to supply make-up fluid to the conduit in quantities in excess of leakage therefrom, an orifice in said conduit adjacent said impact member and operable when open to discharge the excess make-up ilud and relieve the pressure of the uid in said column and .10 operable when partially closed to permit the pressure of the iiuid in the column to build up to an operating value, and a return conduit for conducting excess fiuid from the orifice to the makeup uid supply means.

'7. A hydraulic impact transmitting system comprising, in combination, a conduit, a rst closure reciprocable in one end cf the conduit, an impact member reciprocable in the other end of the conduit, a rigid reciprocable column of liquid occupying said conduit and having its ends in direct contact with said closure and impact member and operable to transmit motion therebetween, means for imparting strokes in one direction to said column comprising an actuating device for said closure, means for imparting return strokes to said column operable on said impact member, means operable to supply liquid tc the conduit in quantities in excess of leakage therefrom, anrorifice in said conduit adjacent said impact member operable when open to exhaust the excess liquid and relieve the pressure of the liquid in said column and operable when partially closed to permit the pressure of the i liquid in the column to build up to an operating value and means for controlling said orice.

8. A power transmission system comprising, in combination, a conduit, a column of liquid therein, closures reciprocably mounted ai; the ends of the conduit and forming the ends of the column,

means for imparting strokes in one direction to the closure at one end of the column, means at said one end operable to supply liquid continuously'to the conduit to maintain the column of liquid therein, means backing the closure at the other end of the column operable to impart; return strokes to the closures and column, a return conduit leading from an outlet orice in said other end of the column t0 return liquid to said supply means, and means at said other end of the column operable to control the pressure of the liquid in the first mentioned conduit by controlling the outlet orifice through which liquid passes therefrom to the return conduit.

9. A power transmission system comprising, in combination, a conduit, a column of liquid therein, closures reciprocably mounted at the ends of the conduit and forming the ends of the column, means for imparting strokes in one direction to the closure at one end of the column, means at said one end operable to supply liquid continuously to the conduit in a quantity in excess of that necessary to maintain the column of liquid therein, resilient means backing the closure at the other end of the column operable to impart return strokes to the closures and column, and means at said other end of the column operable to control the pressure of the liquid in said conduit by varying an outlet orifice for liquid therefrom.

10. In ia hydraulic system comprising a hydraulic column, a power actuator at one end of the column, a sump associated with said actuator, and a constantly operating makeup pump having connections for delivering hydraulic iiuid from said sump into said column; a tool comprising a cylinder with which such column communicates, a plunger reciprocable in the cylinder subject to motion transmitted thereto by said column from said actuator, a return passage in said tool in communication with said sump for the return of excess makeup fluid to said sump, and a valve for which said tool provides a seat and which is operatively disposed in said passage for the 1'1 control of return iiuid, whereby to regulate the pressure in said column.

11. In a device of the character described, `a tool having a hydraulic cylinder, piston, and hydraulic operating connection for use with an actuator which includes a makeup pump for supplying hydraulic uid to saidV connection, and an impactor for transmitting hydraulic shock through such fluid when the iluid is under compression, said tool being provided with a fluid relief port and a valve controlling the discharge of fluid therethrough, said valve regulating the pressure of the hydraulic fluid and the eiect of said impactor on the tool.

12. In a system comprising a hydraulic conduit and an impact mechanism including liquid storage means, "a makeup pump for delivering liquid from said storage means into said conduit and an impactor for delivering successive shocks to a column of liquid under pressure in said conduit; a tool operated by shocks thus delivered and comprising a piston, a cylinder with which said conduit communicates fand in which said piston operates, and means for controlling hydraulic pressure in said conduit, said means comprising a relief valve at said tool capable when open of discharging vliquid Yat least lapproximately as fast as such liquid is supplied to the conduit.

13. A hydraulic impact transmitting system comprising. in combination, a sump for hydraulic liquid, conduits including an outgoing section and 5a return section connected to each other and to said sump to comprise a circulatory system for the hydraulic liquid, -a pump for delivering liquid from said sump under pressure into vthe outgoing section, an impact transmitter comprising a reciprocable face 'exposed to the liquid in one of said sections, an impact receiver comprising a reciprocable face exposed to the liquid in one of said sections, and a restrictor controlling flow of liquid from the returning section t0 the sump and disposed beyond the lpoint in said Ysystem where impacts delivered to the liquid therein are communicated to said impact receiver, whereby to maintain Abetween the impact transmitter and the impact receiver pressure on such liquid adequate for the transmission of impact, while permitting liquid circulation through said system for the cooling thereof and the relief of excess pressure developed by said pump.

References Cited in the ille of this patent UNITED STATES fPATENTS Number Name Date 560,934 Robertson May 26, 1896 671,505 Winsor Apr. 9, 1901 1,496,324 Rockwell June 3, 1924 2,168,806 Reilly Aug. 8, 1939 2,227,279 Smith Dec. 31. 1940 2,389,654 Werff Nov. 27, 1945 2,397,174 Warren et al Mar. 26, 1946 2,413,380 Rush Dec. 31, 1946 2,414,519 Greene Jan. 21, 1947 2,420,406 Andrews et a1. May 13, 1947 v2,437,821 Hughes Mar. 16, -1948

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