US2482790A

US2482790A - Hydraulic vibrator

Info

Publication number: US2482790A
Application number: US3462A
Authority: US
Inventors: Musschoot Albert
Original assignee: Link Belt Co
Current assignee: Link Belt Co
Priority date: 1948-01-21
Filing date: 1948-01-21
Publication date: 1949-09-27
Anticipated expiration: 1966-09-27

Description

p 1949- A. MUSS CHOOT 2,482,790

HYDRAULIC VIBRATOR Filed Jan. 21, 1948 I 6 Shets-Sheet l i swam/tom g Mai/11mm} p 1949- A. MUSSCHOOT $482,790 I HYDRAULIC VIBRATOR Filed Jan. 21, 194 I e Sheets-Sheet 2 3i. f as a,

Q/ #2 I 44 Q ITIIIIIII v 49 llllllll 0 QYWWM I I A. MusscHooT 2,482,790

HYDRAULIC VIBBATOR 6 Sheets-Sheet 3 w Maw W l 5.55 m,

'se t'; 27, 1949.

Filed Jan. '21, 1948 MMMwksaZaai P 1949- A. MUSSCHOOT HYDRAULIC VIBRATOR 6 Sheets-Sheet 4 Filed Jan. 21. 1948 all Ill/Ill p 1949- A. MUSSCHOOT 2,482,790

HYDRAULIC VIBRAIOR Filed Jan. 21, 1948 GSheetS Shee-t 6 l atented Sept. 27, 1 94 HYDRAULIC VIBRATOR Albert Musschoot, Chicago, Ill., assignor to Link- Belt Company, a corporation of Illinois Application January 21, 1948, Serial No. 3,462

This invention relates to new and useful improvements in hydraulic vibrators of the type that is adapted for converting rotary motion into reciprocatory or vibratory motion, and deals more particularly with structural and operational improvements for devices of the type disclosed and claimed in the copending application of Charles Irwin Lattig, deceased, Serial No. 615,350, filed September 10, 1945.

The primary object of this invention is the production of a hydraulic vibrator that embodies all of the basic operational advantages and features of the vibrator device disclosed in the above identified application, but which is constructed of a substantially smaller number of parts which may be more economically manufactured, maintained, and repaired.

Another important object of the invention is to provide a hydraulic vibrator which will function as a power transmission unit for converting rotary motion into reciprocatory' or vibratory motion for driving such commercial machines as oscillating conveyors, feeders, screens and the like; said unit being so constructed that in starting up with the full load of the driven machine applied thereto, the length of the strokes delivered to said actuated machine will be substantially less than the length of the intended full normal stroke, and the amplitude of the delivered strokes will be increased gradually and automatically until such full, normal stroke is obtained. This characteristic of the unit permits a driving motor to be employed which has a smaller starting torque than would be the case if the unit were to deliver the full normal stroke from the very start of its operation.

A further object of the invention is the provision of a hydraulic vibrator that includes a housing, the main section of which is formed of a single casting having all or" its cored passages located in such a way as to permit ready inspection of all internal surfaces for blow holes and other imperfections, and which requires only the machining of flat surfaces and the boring of straight holes to produce the finished housing section.

Still another object of the invention is to construct a vibrator of the type which hydraulically converts the rotary motion of a fluid displacing cam into the reciprocatory motion of a fluid pressure actuated piston so that a housing assembly of any given size readily may be adapted to accommodate cams of different thickness, diameter, and/or eccentricity and pistons of different diameters and/or lengths to provide for'flexibility 19 Claims. (o1-e0 54.5)

of design with reference to the length of the piston stroke and the developed fluid pressure and piston force. a

A still further object of the invention is the provision of a hydraulic vibrator housing which is provided with a separate part for accommodating the rotatable, fluid displacing cam and its as-- sociated followers with the result that mainteferent capacities may be produced by merely varying the size of this separable housing part and its fluid displacing cam.

, A further object of the invention is the provision of means for automatically replenishing the.

fluid that has leaked from the working spaces.

Other objects and advantages of the invention will beapparent during the course of the follow-v ing description.

In the accompanying drawings forming a part of this specification and in which like numerals are employed to designate like parts throughout the same,

Figure l is an end elevational view of the hydraulic vibrator embodying this invention,

7 Figure 2 is a top plan view of the hydraulic vibrator,

Figure 3 is a vertical sectional view taken on line 3-3 of Fig. 2,

Figure 4 is a vertical sectional view taken on line 44 of Fig. 1,

Figure 5 is a vertical sectional view taken on line 5-5 of Fig. 1,

Figure 6 is a vertical sectional view taken on line 66 of Fig. 1,

Figure? is a horizontal sectional view taken on'line l'! of Fig. 1,

a Figure 8 is a fragmentary, horizontal sectional view taken on line 8-8 of Fig. 1,

1 Figure 9 is a vertical sectional view taken on line 9-9 of Fig. 2,

Figure 10 is a vertical sectional view taken on line Ill-l0 of Fi 2,

Figure, 11 is a horizontal view taken on line u of Fig; 1, and r a Figure 12 is a detail, perspective view of a detachable part of the housing.

In the drawings, wherein for the purpose of illustration is shown the preferred embodiment of brator, includes a housing. that is constructed or fabricated of five. separable parts which include.

the main housing section A, the secondary housing 3 section B, the cover section C, the mounting end section D, and the mounting end section E.

By particularly inspecting Figs. 1 to 3 inclusive, 7, and 9 to 11 inclusive, it will be seen that the main section A of the housing is provided with a substantially flat exterior face a at what will be termed its front. These same figures disclose the secondary housing section B as having two opposite, substantially fiat exterior faces I) and 1). Figs. 3, e, '7, and 9 to 11 inclusive disclose these exterior faces 19 and b as being formed with circular grooves it which are of rectangular cross section and are adapted to receive the. compressible packing rings Hi. Figs. 1 to 3 inclusive, '7, and 9 to 11 inclusive disclose the housing cover section C as being formed with a substantially flat, exterior face 0.

Figs. 1 to 4 inclusive, 7, and 9 to 11 inclusive disclose the housing sections A, B and C assembled or engaged so that the exterior faces a. and b are in engagement with each other and so that the exterior faces b and c are in engagement with each other. In the manufacture of these three housing sections, the exterior faces a, b, b and c are machined to provide full face contact or engagement so that the housing sections can be firmly fastened together by the circular series of screws H5. The compressible packing rings it will prevent leakage of the fluid employed in this hydraulic vibrator through the joints that are formed by the engaged exterior faces of these housing sections.

By inspecting Figs. 2, 4. to '7 inclusive and 11, it will be seen that the main housing section A is provided with substantially flat, end faces a, and at". These same figures disclose the mounting end section D of the housing as being positioned to flatly engage the exterior face a of the main housing section A and the mounting end section E as flatly engaging the exterior face a" of the housing section A. screws it are employed for tightly fastening these housing sections together. By inspecting Figs. 1, 2, 4, to '7 inclusive, 11 and 1-2, it will be seen that each one of the mounting end sections D and E of the housing is made up of a face plate ii that is formed with mounting feet is through the medium of which the hydr-aulicvibrator may be attached to a supporting surface by means of the bolts, or the like, l9.

Referring to Figs. 3, 5, 7, 9 and 10, it will be seen that the main housing section A is cored during casting so as to provide a bore throughout its enti e length. That is to say, this bore opens at its opposite ends through the flat, exterior, end faces a and a".

The intermediate portion of this bore is shaped to provide the cylinder 20. Outwardly in opposite directions from this cylinder, the bore is defined by the annular wall portions 2! and 22. These wall portions 2i and 22 result from the provision of fluid passageways and fluid ducts which will be described in detail at later points.

Figs. 5 and 7 best illustrate the opposite end portions of this main housing section bore as being closed by the

plugs

23 and 24 which are carried by the mounting end sections D and E, respectively. That is to say, these

plugs

23 and 24 are integrally formed with the face plates I! of the mounting end. sections D and E.

The plug 23 is formed with a bearing. hole 25 that does not extend all the way through this plug and its associated face plate 11. Additionally, the plug 23. isso cast as to provide a duct portion 25 which intersects the bearing hole 25 and functions, in a manner to be explained more 4 in detail at a later point, to drain fluid into a reservoir.

The plug 2 1 is provided with a bearing hole 2'! that extends entirely through the same and opens through the face plate I? in the form of an enlarged opening 28 that receives a suitable seal assembly 29. This plug 24, also, is provided with a duct portion 39 that assists, in a manner to be described at a later point, in returning fluid leakage to a reservoir.

The inner end portion of each one of the plugs 23: and 213 is provided with a peripheral, annular groove. 35 which is of rectangular shape in crosssection and functions to receive an annular packing ring 32 formed of any suitable compressible material. This packing or sealing ring 32 functions in each, instance to prevent leakage of fluid past the inner end portions of the plugs 23 and 2a and the associated wall portions 2| of the previously referred to bore.

A piston 33- is illustrated in Figs. 3, 5, 7 and 9 as being positioned in the cylinder 2!! for reciprocatory movement therein. This piston is provided with a rod portion 34 at one end which is slideably supported by the bearing hole 25 formed in the plug 23-. The piston 33, also, is provided with a rod portion 35 that is slideably received in the bearing hole 2} formed in plug 24; This piston rod portion 35 extends entirely through the bearing hole. 21- and the enlarged end opening 29 with its seal 29 to project beyond the face plate H of the mounting endsection E.

The extremity of this piston rod portion 35, has detachably mounted thereon an eye coupling or connector member 36 by means of which the strokes of the piston 33' may be applied to the machine that is to be reciprocated by this hydraulic vibrator device.

A protective boot 31-, which is of wafer-like construction andgis formed of two discs of leather, or other suitable flexible material, is positioned on the projecting portion of the piston rod 35, between the coupling or connecting eye 36 and the seal 29. A compression spring 38 is confined within the protective boot 3?! and functions to keep the opposite sides. of the boot in engagement with, the inner end of the coupling eye 36 and the adjacent side of the seal 29.

By inspecting Figs. 4, 5, 7, 8, 9 and 11, it will be seen that the main housing section Ais so cored during casting as to provide two parallelpassageways-39 which are spaced from each other lengthwise. of the housing section A a distance that equals the length of the cylinder portion 29 and are normal to the axis of said cylinder. Fig. 9 best illustrates the shape of each one of these fluid passageways in vertical section. It will be seen. that the lower portion of each passageway communicates with an end portion of the cylinder 29 while the upper portion of each passageway 29 opens at 40-through the substantially flat, exterior face a of the main housing section A. Fig. 4' best illustrates theseend openings it and the parallel arrangement of the same. It will be seenby inspecting Figs. 5 and 7 that these passageways 39 are closed in part at their outer sides by the inner facesof theplugs 23 and 24. Consequently, the lower portions of these passageways 39 may be considered as axial extensions of the cylinder 29 because the piston 33, in reciprocating from its neutral position as illustrated in Figs. -'5 and'7, willmove into and out of the lower end portions of the two passageways 39.

Fig.3, 5, 8and 9-disclose the upper end portions of the fluid" passageways 39 as being placed in 7 closes :a :duct la :for delivering ito athe resets/Foil 58 the fluid tliat leaks along the shaft 11.5.

"This cam shaft projects exteriorly :c'f ithefmam housing .section A at .its:endi15aafor the :purpose of having a-suitable driving i.pulley,-:or the like, mounted thereon through the medium ;of which the shaft may-be'driven by any desired form zo'f prime smover. The remaining end :portion 15b of thei-shaft ."llprojects outwardly .of'thezexteri'or faceuof the main housingsectioniA.

;Figs. 4, 9:-'and.1l illustratethesecondar housingrisection B as having formed .therethroug'h or therein :a' fluid chamber it which is :of arectangtulanshape'in'vertical'section. In other :WOlfdS, this fluid Zchamber "16 opens through the opposite, exterior :face's b and 1b :of :the :secondary :housin-g section B. Figs. '4, 9 and :11 illustrate lthe :fluid chamber l? as being so positioned that itlregisters with the open ends iil of the two fluid.passagewaysdS.

eccentrically bored, fluid 'displacementicam "ll is x-fastened .bya suitable screw, ;or the :like, 2118 on theaend portion lliib of the shaft :75 :and for that reason, the: caml-"l'willrrotate with this shaft. The cam i'SfSD eccentrically:m0unted on thew-shaft that its high side or ;point 1-9 will sweeprthrough or deiine a circle Whose diameter is substantially equal to .the minor .;or vertical dimension of :the fluid-chamber :16.

:Fies. 3 and 4 disclose ,thesecondary mousing section 'B as'having formed'therein, atzdiametrically:oppositerlocations, thezpockets'flii for receiving the follower plates :8 B. These follower plates are caused tobear at their inner. endfaces against the periphery of the cam Tl ebythez compression springs 8.2 which are .socketed in the follower plates 8 8. By particularly inspectingqFig:4;,gitlwill be seen thatuthe, follower platesfiBl cooperate :with theeccentric, fluid displacementxcam Ill-to divide thefiuid chamber 1-6 into two sectionswwithgeach one :of the sections communicating -iwith DIlEfL-Of the passageways :39'through its open 'uppersend 40..

.Figs. fly-1,7,9, 10 and 1:1 'discloseitheouter or front, exterior face 1) ofthe secondary 'rhousing section -.-B as having formed. therein an2annular groove-.83 which is of .proper-diameter toibe :intersectedbythe pockets to which-:receivezthe -fol lowerplates-tl. This groove 83, therefore,'interconnects .the .two pockets 31] to :prevent the :development-of .unequalfluid-pressures therein. *Instantaneous pressures developed in :;chamber 16 are permitted to be transmitted through :the pockets :81! around therfollower plates, duexto'the working clearances necessarily provided tbetween these .parts, etc the annular groove 83 a and .maintain the follower plates :in hydraulic balance. This condition reduces the icontact pressuresxbetweenthe follower plates -81 .and the. cam -.'|-'l ,-to.;a minimum, permits very.- light .compressionsprings Bite .be employed, and reduces the Wear on-the followerplates Stand thelcam surface to :aminimum. 7

.By inspecting Figs. 3, .9..and .11, .itmvil-l be seen that the cover section Cofthe housing completely coversthe exterior face 2) of'thesecondaryhousing section'B and thereby completely closes .Zthe outer side of the'fiuid chamber 115. "These figures also-illustrate the fact'that the axial "dimension of the eccentric, fluid displacement cam 1"! is such that it substantially corresponds --With the awesome the opposed exterior faces wandrc .of :thesmain housing ssection /A:and ithe couer section'IC,;respectively. it will! be appreciated, therefore, that the amountzof efluidsthatis displaced ,bythe rotation of the ram 111 unay :be changed :by increasing or decreasing rthe :thickness .of .the secondary imusing section :15 and aby :maintaining the .same relativettlimensions betweenzzthezthickness of:this secondary :housing section and the thickness, tor axialdimensionlof i.-the acam ll.

At this point, it is believed to be advisable to note rthatzthe diameter ;of the cam 17.! sand/or its eccentricity can the varied :and the diameter and/or lengthmfitheypiston 33 tmay'bexvaried iio prouidehiorsextreme flexibility of design-withmeferencezto thellengt'hlof thegpiston stroke and the izuiidspressurerandzpistoniforce that are developed. :ilhe mode .of operation of the hydraulic xvi bratorsemhodyingtthis;inventioniwillrbe explained as follows:

:Itwill appreciated that .zrotation 501 :the cam shaft "E5,.=:hy the application of :power ato'its projecting :end portion at'k5a, will cause .;the :fluid displacement cam 'lktoibe rotatedoin thefluidchamber :15.

The interiorof the .ihydraulic vibrator housing is: dividedintoewhatsmightbe:ztermed two working spaces fOI' alike fluid. Each .one of these spaces he consideredas consisting-10f one-sectionqor side portion .of the :fluid achamber :15, the -.-communicatingr-fluidpassageway 39, and-theadjacent end ,sportiom of :the a cylinder 3.0 when :piston 1:33:15 dis aced :therefrom. it :will be :seen, :therefore, that therfiuidmyepass duct 4| -:establishes'a flow path 5b.";- tween zthese llWlLO fluid-working spaces. also, will EbfiFflQfiIl-ithEI: each one .of ithese'working spaces cani be-ssupplied with fluid'fromthe reservoir rithrougzh lthezassociated check valve assembly thatis made up .of the partsi63 2130268 ;inelusive.

GI-f 2W8 :oon-sider that :the two fluid working 1 665: f fi fi i fllyifilledWith fluid and thatthe byepass control valve :seat #13 is in the fully open position illus-t1rated :in ,zhis 8.. :clockwise rotationqof ithe-ioam 11,5366 Fig. 4, will causegfl-uid to.,b isplaced fromthe riehtshand sectionofithe fluid: ,aamber Jib-beginning when the logy/point or side -.-passes -through the right horizontal center ,-pointsand r continuing :until the low point or side=5 reachestor. coincides with the left horizontal icenter g'poin-t, and this :fluid .will flow through the associated passageway 39 tozthaassoeiated-..end -of the fluid 'bY-DaSs duct 4:1 and through i this duct into :the .other fluid ppassagemay :39 :and thence i-nto =.the -leftehand sectioneof thefluidwchamher t5. With -theby-pass--;contro1 valves in 2 its ,tully open position, fluid equal-:to the amount displaced from one of the :sections of the fiu-id'lehamber 1 6 will be delivered; into .;the other section .of this fluid chamber and .;no {differential pressures will be applied ito the end taoes'eof the-piston 13. Gonsequentl-y, this piston will not be moved and the maohi-neinot shown, :that is to-be connected to the outer end ofthe piston rod ,35 will not be actuated.

.By..adjusting ,the byepasscontrol valve'43 :to theJeiit-of ,E ,5,.the area ofathe fluid ifiow path provided by the Jay-passduct M .will bexreduced. ,As the .area of this by-pass duct .is reduced, less fluid ..Will .be permitted to :flow back and forth through-.the..ductcrwith the-result that-fluidpressure be (applied-Wm one .face .of the piston datduning each period that afiuid .is :jdisplaced fromaon-er' the other ofithesectionspf thes'flui'd chamber 211B. :Qonsequentlm-as ;;the piston.l33

communication with each other by a fluid bypass duct 4|. This duct, when it is not completely closed, permits fluid to flow back and forth between the two passageways 39. It will be explained more in detail at a later point that this alternate flow of fluid through the by-pass duct 4| controls the amplitude of the stroke of the piston 33. Consequently, it is desirable to be able to regulate or control the volume of the fluid that passes back and forth through this by-pass duct.

igs. 5 and 8 best illustrate the type of valve that is employed for regulating this flow of fluid. This valve includes a body 42 formed with a tapered valve seat .3 intended to cooperate with the adjacent end edge of the by-pass duct M. The valve further includes a stem 44 that extends to and is suitably connected with a second body 45. The bodies 42 and 45 are slideably received in and supported by the openings 46 and d1, respectively. An internally threaded opening 48 is formed in one end wall of the main housing section A for the reception of a threaded plug 49. This plug is provided with an inter-- nally threaded opening 58 in which is adjustably mounted a set screw 5|. This set screw is intended to bear against the outer end face of the valve body 52 and may be adjusted inwardly and outwardly to change the position of the tapered valve seat 43 relative to the end edge of the by-pass duct 'll. A look nut 52 is adjustably threaded on the set screw 5| and functions to retain this set screw in any desired adjusted position. The set screw may be adjusted from out- Side the housing of the hydraulic vibrator by inserting a suitable tool in the slotted end 53 thereof. The valve body 45 is bored at 54 for receiving one end of a compression spring 55. The remaining end of this spring bears against a removable plug 55 that is threaded in an internally screw-threaded hole 5! formed in the adjacent end wall of the main housing section A.

Figs. 5 and 8 illustrate the tapered valve seat 43 arranged in its substantially fully opened position or so that the desired maximum amount of fluid can flow back and forth through the bypass duct 4!. From this position, the tapered valve seat 53 can be adjusted inwardly until it bears against the edge of the by-pass duct 4|, or so that this duct is entirely closed off. When in this position, no fluid will flow through the by pass duct.

Figs. 3, 6, and 7 illustrate the rear, lower portion of the main housing section A as having formed therein a fluid reservoir 58. Figs. 6 and 7 illustrate this reservoir as extending entirely through the main housing section A from end to end so that the opposite ends of the same are closed by the face plates ll of the mounting end sections D and E. Figs. 2 and 6 disclose this res ervoir 58 as being provided with a removable plug 59 for closing a filling opening 68 for the reservoir.

Figs. 5 to 8 inclusive, 1? and 11 disclose the main housing section A as being provided with two, vertically arranged, substantially parallel ducts 8| that are formed therein by proper coring at the time of casting. Fig. best illustrates the shape in vertical section of each one of these fluid ducts 5|. It will be seen that the lower, rear end portion of each duct communicates with the adjacent end portion of the reservoir 58 while the upper forward end portion opens through the substantially flat, exterior face 12 of the main housing section A as at 62. Figs. 5,

land 10 best illustrate the fact that the fluid ducts 6| are so positioned as to register with the previously described

duct portions

26 and 3| that are formed in the end plugs 23 and 24, respectively, of the mounting end sections D and E.

The fluid ducts 5| and their aligned

duct portions

25 and 35 are intended to function to return to the reservoir 58 any fluid that leaks outwardly along the

piston rod portions

34 and 35 and outwardly along the valve bodies and 46. It will be appreciated that no packing means are provided for either one of the

piston rod portions

34 and 35 or for either one of the

valve bodies

45 and 46. Consequently, because the fluid that will occupy the passageways 35 normally will be under pressure, there will be a certain amount of fluid leakage from the fluid passageways 39 into the fluid ducts 6| and the

duct portions

26 and 30.

Because the return of fluid to the reservoir 58 occurs at a. substantially constant but relatively slow rate during the entire operating period of the hydraulic vibrating device, and also for a short time after the device is stopped, it is necessary to provide means for delivering fluid from the reservoir 58 into each one of the fluid passageways 38. This delivery of fluid from the reservoir 58 to the passageways 39 functions to fill up the working spaces of the hydraulic vibrator when the latter is started up and also functions to maintain the working spaces filled with the proper amount of fluid during each operating period. It will be appreciated, therefore, that the fluid circulates during each entire period of operation of the hydraulic vibrator and, for that reason, acts as a coolant and lubricant for the moving parts.

Figs, 3, 6, 7 and 9 disclose check valve devices which function to deliver the fluid from the reservoir 58 to the two fluid passageways 39 during each operating period of the hydraulic vibrator. By particularl referring to Figs, '7 and 9, it will be seen that a duct 63 is formed in the main housing section A in alignment with each one of the fluid passageways 39. Each one of these ducts has a small delivery aperture that opens into its associated passageway 39. The remaining end of each one of these ducts 53 has threaded therein a substantially tubular valve casing 65 for housing the spring-loaded check valve 65. This valve normally functions to close an aperture 61 formed in one end wall of the casing -65. The remaining end of the casing is provided with a centrally apertured disc or plug 58. By inspecting Fig. 9, it will be seen that the check valve body 68 will be displaced from its seat against the pressure of its spring when the pressure in the associated fluid passageway 39 is less than the pressure prevailing in the reservoir 58.

Figs. 3, 7 and 9 disclose the rear wall of the reservoir 58 as having threaded opening 69 formed therein in alignment with the check valve casings 65 and removable plugs l0 threaded in these openings. These plugs, of course, can be removed to obtain access to the check valves.

Figs. 3, 5 and 11 disclose the main body housing section A as having a bore H formed therethrough so as to open through the substantially flat, exterior, front face a of the housing section and as opening through the rear face of the section. At the rear face, the bore H is enlarged at T2 to accommodate a suitable sealing unit 13. Bearing bushings 14 are mounted in the bore 1| to rotatably support the cam shaft 15. Fig. 3 disdisplaced in one direction bythe fluid pressure that is applied to one of its faces, by the displacement of oil from one section of the fluid chamber 1%, the remaining face of the piston i the fluid that is displaced from one section of the fluid chamber 16 by the action of the cam will be applied to the associated end face of the piston 33 while all of the fluid that is displaced by the opposite face of the piston will be caused to flow into the other section of the fluid chamber It will be appreciated, therefore, that the length or amplitude of the strokes of the piston 33 can be varied by adjusting the by-pass control valve seat 43 relative to the associated end edge of the by-pass duct 4!. In other words, the length or amplitude of the strokes of the piston 33 may be varied between zero, where no movement of the piston occurs, and maximum, where the piston 33 moves in opposite directions through its intended full, normal stroke. The zero stroke of the piston is provided when the by-pass valve seat 43 is moved the maximum distance away from the associated end edge of the by-pass duct 4|. The maximum stroke of the piston 33 is provided when the by-pass valve seat 43 engages the associated end edge of the by-pass 4|.

Probably one of the most important and novel operational characteristics possessed by this hydraulic vibrator unit is its ability to automatically adjust the length of the strokes of the piston 33 from substantially zero to maximum during each starting up period, without resorting to any adjustment of the by-pass control valve 43 to vary the rate of flow of fluid through the by-pass duct ll, with the result that the unit can be driven by a low starting torque motor even when it is started up under a full load.

The reason for this novel characteristic will be understood when it is explained that a part of the fluid leaks or drains from the two fluid working spaces into the reservoir 58 during each nonoperating period of the unit; the maximum piston stroke, for any given setting of the by-pass 7 description of this action will be desirable at this point.

Let us assume that the unit has been idle long enough for fluid to have drained into the reservoir 53 from the two fluid working spaces until the reservoir is full or until a common fluid level prevails in the reservoir and the two working spaces. When the unit is started up, the fluid chamber is will be only partially filled with fluid and the cam "l1, whichnormally begins to displace fluid as the low point or side 85 moves past the horizontal center line, will be permitted to move into one half section of the fluid chamber 16 without displacing any fluid from this section until or unless the advancing cam and the existing fluid finally collectively fill this fluid chamber section. If the cam and the existing fluid donot, or do no more than, completely fill the half section of the fluid chamber by the time the high point or side 19 of the cam arrives at the horizontal center point, no fluid pressure will be applied to the associated face of the piston 33 and no piston movement will be produced.

During this same half cycle of rotation when the cam 11 would normally displace fluid in one half section of the fluid chamber 16, the cam has receded or increased the volume of the other half section of the fluid chamber 16. Inasmuch as therehas been'no movement of piston 33 during this half cycle, there will be an increase in the volume or unoccupied portion of the last mentioned half section of the fluid chamber which will cause a reduction in pressure in this chamber section. This reduction in pressure causes a pressure drop at the check valve 5566 which will cause this valve to open and admit fluid from the reservoir into the fluid working space that is partially formed by the half chamber section in which the pressure'reduction occurred. The viscosity of the fluid and the inertia of the fluid and the check valve parts may require several replenishing cycles to occur before both of the fluid working spaces are completely filled and the stroke of the piston 33 will be increased to the intended full normal stroke. Y

When this replenishing'of the fluid in the two working spaces approaches the point where the spaces are almost filled with fluid, the action changes. Assuming that the cam 11 is in the position illustrated in Fig. 4, it will be understood that the actuating pressures prevailing in the two half sections of the fluid chamber 16 are at zero and the velocity of reciprocation of the power delivering eye 36 and the displacement of the fluid are at maximum. As the high side or point 19 of cam Tl passes the top vertical center, the velocity of displacement of the fluid is decelerated by the sinusoidal action of the cam. This deceleration of the fluid acts to decelerate the piston 33 and its associated parts, including the machine parts that are connected to the actuating eye 36, and to build up the pressure in the half section of the fluid chamber 16 through which the 10W side or point 85 of the cam is moving. From the above, it will be seen that the pressure in the last mentioned half section of the fluid chamber 16 is maximum when the high point or side 19 of the cam is at the horizontal center point of the other half chamber section and the pressure approaches zero as the high point or side '19 of the cam approaches the vertical, bottom center point.

Still referring to the disclosure of Fig. 4, if the half section of chamber 15 at the left of cam 11 is not completely filled with fluid as the high point or side 19 of the cam passes the top vertical center point, no deceleration of the piston 33 will occur until'this half chamber section is completely filled with fluid.v During this operation of the cam, the

, reciprocation of the piston is producing an increase in the volume or the unoccupied portion of the right-hand chamber section at a faster rate than the cam T! is decreasing the volume of this right-hand chamber section. This action produces a reduction of pressure in this chamber section and replenishing of the'fluid through. the

:aisenoo i1 1 gilSSQCiELtGd 'check \valve again takes place. This :action continues until 'rbOth of the :fluid working spaces are entirely filled-withafluid.

From the aboveldescription of the operation of ethis hydraulic vibrator unit it-iwill beappreciate thatit is=notnecessary-to employaseparate fluid y purnp to maintain the two {fluid working spaces filled during operationaof itheiunit nor. is it necessary to employ-a-fiuid vreservoir that is so posiitioned that'it wilLmaintaimthe two fluid Working spaces flooded at:allltim es as a result of gravitational fiow of 'fiuid from the :reservoir into said spaces.

It has been stated :above that this hydraulic vibrator unit automatically adjusts the lengths ,of the strokes of -the;piston :33 from; substantially -.zero .to maximum :during each startingup period, megardless .of the setting of the bypass control -valve =43. rSoifar, the explanation of-why this important and novel iactionfoccurs has been given 1 :QYIIy forstarting up operationsawhen the unit has beenstandingidle=asuflicient length :of time for :a substantial amount-of the :fluid to leakor drain iirom the vitwo Working spaces .111110 :the reservoir 5,8. It willibcstatedmowthat thesame gradual It will be considered that the cam ll starts rotating ,at its intended normal or maximum speedas soon was :its driving :motor is energized. -Consequently, the cam i157 instantaneously ,at-

tempts to convert the staticcondition of the fluid in the two working spaces, ithe piston-'33 and rod d5 with its coupling-10x Loonnector :eye 36, and the (machine to aloe oscillated to their full or normal working condition or movements. Theresistance tothe rotation of thc'cam Tl -createdzby the static fluid sand mechanical parts naturallycauses abinormally vhigh and low pressures to be created v-simultaneouslyiin-the twosections of fluid chamber .Hiswith the result thatvthe fluid is caused to 1eak;from-.one:fiuid chamber section to the other past the ,cam. The leakage, of :course, is made possible ,iby the working clearances which must necessarily be :provided between the .side .faces of thecam 11:1 and the exterior faces a and c of the housingsections .A and ,C. This leakage of fluid permits thecam :tOslip relative to the piston 1 -33 with the result that the initial piston stroke is very short. As the load is gradually picked @up the amount .of fluid leakage and .cam slippage decreases and the length of :the :strokes oi the -pjiston;gradually increases until the full or normal 7 parts consists of the machining of fiat exterior faces 1 and the boring of straight holes.

It-is :to'be'understood that the form of this invention herewith shown and described is to be taken as the preferred example of the same, and

that various changes in the shape, size, and arirangement of parts may be resorted to without departing from the spirit of the invention .or the scope .of thesubjoined claims.

Having thus described the invention, I claim:

1. In :a hydraulic vibrator for converting roitaryrmotion into reciprocatory-motion, a housing comprising a'main section-having formed therein :a cylinder and-a separate fluid passageway extending zfrom each :end of the cylinder to and opening through an exteriorface of said section, a secondary section engaging said face of the main section and having a fluidchamber extending therethrough and positioned to communicate with the open ends of said fluid passageways, a cover section engaging-the secondarysection for .closing the outer side-of the :iluidchamberyand :means for fastening together"saidhousing'secztions; apiston reciprocatinginthecylinder of the "main housing section,a rod attached to said pisiton and projecting from the housing for connection WiththeJmachine to be reciprocatedby the :hydraulic vibrator, a rotatable shaft jourrnaled in the housing :and :having one end portion projecting therefrom to be driven by a prime zmoverrand having its other end portionjprojcotzing into said fluid chambena fluid displacement scam partially filling said fluid chamber and mounted on the last mentioned end portion of .said shaft :for rotating therewith, and 11163115100- operating with the periphery of said cam 5oz" di- :vidingxthe unfilled "portion of the ifluid chamber into two separate sections which communicate respectively with the aforesa'idseparate fluidpas- :sageways, whereby rotation-'of'the cam will :cause fiuidto flow alternately in opposite directions be- :tween each :flu'id chamber section and the :cylin- :der rend portion connected thereto 3170 bring :about reciprocation of ".the piston in :the :cylinder in atimed relation to the rotation of the cam.

2. In a hydraulic vibrator for converting F110- tary motion into reciprocatory motion, alhousing comprising 'a main section having iformed therein a cylinder and aseparate fluid passageway extending from each end of 'the cylinder to and opening through an exterior face of said .section, a secondary section engaging said face 0f the main sectionand havingsa fluid charriber extending therethrough and positioned to communicate with the openends of said fluid-passageways, a cover sectioniengaging the secondary section'for closing the outer side of the fiui'ol chamber, and means for fastening together said housing sections; a piston reciprocating in the cylinder of the main housing section, a rod attached to said piston and projecting from the housing for connection with the machine to he reciprocated by the hydraulic vibrator, a rotatable shaft journaled in the "housing and having one end portion projecting therefrom to be driven by a prime mover and having its other end portion projecting into said fluid chamber, a fluid displacement cam partially filling said fluid chamber and mounted on the last mentioned end portion of said shaft for rotating therew'ith, means cooperating with the per'ipher y of said cam for dividing the unfilled'portion of the fluid chamber into two separate sections which communicate respectively with the aforesaid separate fluid passageways, whereby rotatiomof the cam will cause fluid to flow alternately in'oppo site directions between each fluid chamber section and the cylinder end "portion connected thereto to bring about reciprocation of the piston 'in the cylinder in timed relation to the rotation of the cam, and means for varying the amplitude of reciprocation of the piston.

3. In a hydraulic vibrator for converting rotary motion into reciprocatory motion, a housing comprising a main section having form-ed there- :in a cylinder, asBpa-rateJ-fluid passageway extending from each end of the cylinder to and opening through an exterior face of said section, a fluid rate fluid passageways; a cover section engaging the secondary section for closing the outer side of its fluid chamber; means for fastening together said housing sections; a piston reciprocating in the cylinder of the main housing section, a rod attached to said piston and projecting from the housing for connection with the machine to be reciprocated by the hydraulic vibrator; a rotary shaft journaled in the housing and having one end portion projecting therefrom to be driven by a prime mover and having its other end portion projecting into said fluid chamber, a fluid displacement cam partially filling said fluid chamber and mounted on the last mentioned end portion of said shaft for rotation therewith; a check valve in each one of the fluid ducts leading from said reservoir and operable to admit fluid into its associated passageway in response to a 7 drop in pressure in the latter; and means cooperating with the periphery of said cam for dividing the unfilled portion of the fluid chamber into two separate sections which communicate respectively with the aforesaid separate fluid passageways, whereby rotation of the cam will cause fluid to flow alternately in opposite directions between each fluid chamber section and the end portion of the cylinder connected thereto to bring about reciprocation of the piston in the cylinder in timed relation to the rotation of the cam.

4. In a hydraulic vibrator for converting rotary motion into reciprocatory motion, a housing comprising a main section having formed therein a cylinder, a separate fluid passageway extending from each end of the cylinder to and opening through an e gterior face of said section, a fluid reservoir, and a separate fluid duct leading from the reservoir into each one of said fluid passageways, a secondary section engaging said exterior face of the main section and having a fluid chamber extending therethrough and positioned to communicate with the open ends of said separate fluid passageways, a cover section engaging the secondary section for closing the outer side of its fluid chamber, and means for fastening together said housing sections; a piston reciproeating in the cylinder of the main housing sec-. 1

tion, a rod attached to said pistonv and project ing from the housing for connection with the machine to be reciprocated by the hydraulic vibrator; a rotary shaft journaled in the housing and having one end portion projecting therefrom to be driven by a prime mover and having its other end portion projecting into said fluid 1 chamber, a fluid displacement cam partially filling said fluid chamber and mounted on the last mentioned end portion of said shaft for rotation therewith; a check valve in each one of the' end portions of said cylinder, whereby rotation of the cam will cause fluid to flow alternately in opposite directions'between each fluid chamber sectionand the end of the cylinder connected thereto to bring about reciprocation of the piston in the cylinder in timed relation to the rotation of thecam; and means for varying the amplitude of reciprocation of the piston.

5. In a hydraulic vibrator for converting rotary motion into reciprocatory motion, a housing comprising a main section having formed therein a cylinder and a separate fluid passageway extending from each end portion of the cylinder to -and opening through an exterior face of said section, a secondary section'engaging said face of the main section and having a fluid chamber reciprocating in the cylinder of the main housin section, a rod attached to said piston and projecting from the housing for connection with the machine that is to be reciprocated by the hydraulic vibrator, a rotatable shaft journaled in the housing and having one end portion projecting therefrom to be driven by a prime mover and having its other end portion projecting into said fluid chamber, a fluid displacement cam partially filling said fluid chamber and mounted on the last mentioned end portion of said shaft for rotation therewith, and means cooperating with the periphery of said cam for dividing the unfilled portion of the fluid chamber into two separate sections which communicate respectively with the aforesaid separate fluid passageways extending from the end portions of said cylinder, whereby rotation of the cam will cause fluid to flow alternately in opposite directions between each fluid chamber section and the end of the cylinder connected thereto to bring about reciprocation of the piston in the cylinder in timed relation to the rotation of the cam.

6. In a hydraulic vibrator for converting rotary motion into reciprocatory motion, a housing comprising a main section having formed therein a cylinder, a separate fluid passageway extending from each end of the cylinder to and opening through a face of said section, and a fluid by -pass duct establishing communication between said separate fluid passageways remote from their open ends, a secondary housing section engaging said face of the main section and having a fluid chamber extending therethrough and positioned to communicate with the open ends of said separate fluid passageways, a cover section engaging the secondary section for closing the outer side of the fluid chamber, and means for fastenin together said housing sections; valve means for varying the flow of fluid through said by-pass ducts,means for adjusting said valve means from the exterior of the housing, a piston reciprocating in the cylinder of the main housing section, a rod attached to said piston and projecting from the housing for connection with the machine that is to be reciprocated by the hydraulic vibrator, a rotatable shaft journaled in the housing and having one end portion projecting therefrom to be driven by a prime mover and having its other end portion projectmounted on the last mentioned end portion of 7 e exterior face of the main section, a cover section said st ait for rotation therewith, and means coepe ti g with the periphery of said cam for 1 ding the unfilled portion of the fluid chamleer into two separate sections'which communieate respectively with the aforesaid separate fluid passageways extending from the end portions of the said cylinder, whereby rotation of the will cause fluid to flow alternately in oppos e directions between each fluid chamber section and the end portion of the cylinder connested thereto to bring about reciprocation of the piston in the cylinder in timed relation to the retation of the cam,

{7, In hydraulic vibrator for converting rotary motion into reciprocatory motion, a housing cornpr s' a main section having one flat exterior face a secondary section having two opposite faces pne of which engages the said thenethrough with an end of the first of said bores opening through the exterior face of said section and with the middle portion of the $9 101 01 said bores shaped to form a cylinder,

i WO fluid passageways positioned so as to have end of each communicating with the second of said bores outwardly of the ends of the cylinder extending to and opening at their other ends through the exterior face of said section, plug members having bearing openings formed therein fitted into the opposite end por-' tions of the second of said bores outwardly of the said communicating ends of said passageways; said secondary housing section having a chamber formed therein and opening through its two exterior faces in a position to be closed at one end by the cover section of the housing and to register at its other end with the end of the bore and the ends of the two passage- Ways which open through the exterior face of the housing section; a rotatable shaft iournaled in the first bore of said hop section and having one end portion projecting outside of the housing to be driven by a prime mover and having its other end portion projecting into the fluid chamber of the secondary housing said fluid chamber and mounted on the mentioned end portion of the shaft for rotation therewith, and means cooperating with the periphery of said cam for dividing the unfilled porticn of the fluid chamber into two separate sections which communicate respectively with the two fluid passageways, whereby rotation of the will cause fluid to flow alternately in oppesite directions through said passage 'ays between the opposite end portions of said cyl der and the respective fluid chamber sections; a piston positioned in said cylinder to be reciprocated by the aforesaid alternate flow of fluid, rod means for said piston movable in the bearing hoies formed in the plug members and having one projecting from the housing for connection with the machine that is to be reciprocated by the hydraulic device.

8. In. a hydraulic vibrator for converting rotary motion into reciproca tory motion, a housing comprising a main section having one flat exterior ,face, a secondary section having two opposite exterior faces one of which engages the said exterior face of the main section, a cover section having one exterior face engaging the remaining section, a fluid displacement cam partially exterior face of the secondary section, and means for fastening together said housing sections; said main housing section having two bores formed therethrough with an .end of the first of said bores opening through the exterior face of said section and with the middle portion of the second of said bores shaped to form a cylinder, two fluid passageways positioned so as to have one end of each communicating with the second of said bores outwardly of the ends of the cylinder and extending to and opening at their other ends through the exterior face of said section, and plug members having bearing openings formed therein fitted into the opposite end portions of the second of said bores outwardly of the said communicating ends of said passageways; said secondary housing section having a fluid chamber formed therein and opening through its two exterior faces in a position to be closed at one end by the cover section of the housing and to register at its other end with the end of the bore and the ends of the two passageways which open through the exterior face of the main housing section; a rotatable shaft journaled in the first bore of said main housing section and having one end portion projecting outside of the housing to be driven by a prime mover and having its other end portion projecting into the fluid chamber of the secondary housing section, a fluid displacement cam partially fllling said fluid chamher and mounted on the last mentioned end porticn of the shaft for rotation therewith, and means cooperating with the periphery of said cam for dividing the unfilled portion of the fluid chamber into two separate sections which communicate respectively with the two fluid passageways, whereby rotation of the cam will cause fluid to flow alternately in opposite directions through said passageways between the opposite end portions of said cylinder and the respective fluid chamber sections; a piston positioned in said cylinder to be reciprocated by the aforesaid alternate flow of fluid, rod means for said piston supported in the bearing holes formed in the plug members and. having one end projecting from the housing for connection with the machine that is to be reciprocated by the hydraulic vibrator and means built into the main housing section and controllable from the exterior of the housing for varying the amplitude of reciprocation of the piston.

9. In a hydraulic vibrator for converting rotary motion into reciprocatory motion, a housing comprising a main section having one exterior face, a secondary section having two opposite exterior faces one of which engages the said exterior face of the main section, a cover section having one exterior face engaging the remaining exterior face of the secondary section, packing means between the engaged exterior faces of the housing sections to prevent leakage of fluid therebetween, and means for fastening together said housing sections; said main housing section having two bores formed therethrough with an end of the first of said bores opening through the said exterior face of that section and with the middle portion of the second of said bores shaped to form a cylinder, two fluid passageways positioned so as to have one end of each communicating with the second of said bores outwardly of the ends of the cylinders and extending to and opening at their other ends through the exterior face of said section, plug members, having bearing holes formed therein, fitted into the opposite end portions of the second of said bores outwardly of the communicating ends of said passageways, and packing means between the plugs and the engaged parts of the said second bore to prevent leakage of fluid therebetween; said secondary housing section having a fluid chamber formed therein and opening through its two exterior faces in a position to be closed at one end by the cover section of the housing and to register at its other end with the end of the bore and the ends of the two passageways which open through the exterior face of the main housing section; a rotatable shaft journaled in the first bore of said main housing section having one end portion projecting outside of the housing to be driven by a prime mover and having its other'end portion projecting into the fluid chamber of the secondary housing section, a fluid displacement cam partially filling said fluid chamber and mounted on the last mentioned end portion of the shaft for rotation therewith, and means cooperating with the periphery of said cam for dividing the unfilled portion of the fluid chamber into two separate sections which communicate respectively with the two fluid passageways, whereby rotation of the cam will cause fluid to flow alternately in opposite directions through said passageways between the opposite end portions of said cylinder and the respective fluid chamber sections; a piston positioned in said cylinder to be reciprocated by the aforesaid alternate flow of fluid, and rod means for said piston movable in the bearing holes formed in the plug members and having one end portion projecting from the housing for connection with the machine that is to be reciprocated by the hydraulic device.

10. In a hydraulic vibrator for converting rotary motion into reciprocatory motion, a housing comprising a main section having one exterior face, a secondary section having two opposite exterior faces one of which engages the said exterior face of the main section, a cover section having one exterior face engagingthe re- 'maining exterior face of the secondary section,

and means for fastening together said housing sections, said main housing section having a cylinder formed therein, a piston positioned to reciprocate in said cylinder and having a rod projecting from the housing for connection with the machine to be reciprocated by the hydraulic vibrator, said secondary housing section having a fluid chamber formed therein with its opposite ends opening through the two exterior faces of that section so as to be closed by the engaged exterior faces of the said main and cover housing sections, a rotatable drive shaft having one end portion projecting into said fluid chamber and its other end portion projecting from the housing, a fluid displacement cam positioned in the fluid chamber and mounted on the first mentioned end portion of said shaft, said cam having its opposite end faces positioned relative to the said exterior faces of the main and cover housing sections so as to provide only a working clearance therebetween and being of such a diameter 18 nected cylinder end portion to effect reciprocation of the piston in timed relation to the rotation of the cam.

11. In a hydraulic vibrator for converting rotary motion into reciprocatory motion, a housing comprising a main section having one exterior face, a secondary section having two opposite exterior faces one of which engages the said exterior face of the main section, a cover section having one exterior face engaging the remaining exterior faceof the secondary section, and means for fastening together said housing sections, said main housing section having a cylinder formed therein, a piston positioned to reciprocate in said cylinder and having a rod projecting from the housing for connection with the machine to be reciprocated by the hydraulic vibrator, said secondary housing section having a fluid chamber formed therein with its opposite ends opening through the two exterior faces of that section so as to be closed by the engaged eXterior faces of the said main and cover housing sections, a rotatable drive shaft having one end portion projecting into said fluid chamber and its other end portion projecting from the housing, a fluid displacement cam positioned in the fluid chamber and mounted on the first mentioned end portion of said shaft, said cam having its opposite end faces positioned relative to the said exterior faces of the main and cover housing sections so as to provide only a Working clearance therebetween and being of such a diameter as to cause it to only partially fill said fluid chamber, means operatively associated with the secondary housing section and the periphery of the cam for dividing the unfilled portion of the fluid chamber into two sections, and two fluid passageways connecting the two sections of the fluid chamber to the opposite end portions of the cylinder so that rotation of the cam will cause fluid to flow alternately in opposite directions between each fluid chamber section and its connected cylinder end portion to effect reciprocation of the piston in timed relation to the rotation of the cam, said main housing section having a fluid reservoir formed therein, duct means formed in the housing for draining into the reservoir the fluid thatleaks from the cylinder along the piston rod and from the fluid chamber along the cam shaft, duct means formed in the housing for delivering fluid from the reservoir to each-connected fluid chamber section and cylinder end portion, and check valvesin the last mentioned duct means for allowing such a delivery of fluid to occur as a result of rotation of the cam when the unoccupied portion of the fluid chamber is not entirely filled with fluid.

12. In a hydraulic vibrator for converting rotary motion into reciprocatory motion, a housing comprising a main section having one exterior face, a secondary section having two opposite exterior faces one of which engages the said exterior face of themain section, a cover section having one exterior face engaging the remaining exterior face of the secondary section, and means for fastening together said housing sections, said ,main housing section having a cylinder formed therein, a piston positioned to reciprocate in said cylinder and having a rod projecting from the housing for connection with the machine to be reciprocated by the hydraulic vibrator, said secondary housing section having a fluid chamber formed therein with its opposite ends opening through the two exterior faces of that section so as to'be closed by the engagedexterior faces of the said main-and cover housing sections, a rotatable drive shaft having one end portion :projecting into said fluid chamber and its other end portion projecting from the housing, a fluid displacement cam positioned in the fluid chamber and mounted on the first mentioned end portion of said shaft, said cam having its opposite end faces positioned relative to the said exterior faces .of the main and cover housing sections so as to provide only a working clearance therebetween and being of such a diameter as to cause it to only partially fill said fluid chamber, means operatively associated with the secondary housing section and the periphery of the cam for dividing the unfilled portion of the fluid chamber into two sections, and two fluid passageways connecting .the two sections of the fluid chamber to the opposite end portions of the cylinder so that rotation 'of the cam will cause fluid to flow alternately in opposite directions between each fluid chamber section and its connected cylinder end portion to effect reciprocation of the piston in timed relation to the rotation of the cam, said main housing section having formed therein a by-pass duct connecting the two fluid working spaces, each one of which comprises a fluid chamber section, an end portion of the cylinder, and the fluid passageway connecting the same, said by-pass duct being provided to allow fluid to flow alternately in opposite directions therethrough between said two fluid Working spaces in response to rotation of the fluid displacement cam, and a valve controllable from the exterior of the housing for varying the rate of flow of fluid through said by-pass duct to regulate the amplitude of reciprocation.

13. In a hydraulic vibrator for converting rotary motion into reciprocatory motion, a housing comprising a main section having one substantially flat exterior face and having a bore extending through the section from end to end with the intermediate portion of the bore forming a cylinder, a plug fitted in each end portion of the bore outwardly of the cylinder, each plug having a face plate at its outer end for attachment to the end of said main section, feet for mounting the hydraulic vibrator on a supporting surface, and a bearing opening, one of said plugs having its bearing opening of suflicient length to extend entirely through the plug and its face plate, a piston reciprocating in the cylinder, and rod means for the piston slideable in said bearing openings and projecting from the main housing section through said longer bearing opening for connection with the machine to be reciprocated by the hydraulic vibrator; a secondary housing section having two opposite substantially flat exterior faces, one of which engages the said exterior face of the main housing section, and having a fluid chamber formed therethrough between its said exterior faces, a rotatable shaft journaled in the main housing section to extend into the fluid chamber at one end and to extend from the housing at its other end for connection with a prime mover, a fluid displacement cam partially filling said fluid chamber and mounted on the adjacent end portion of the rotatable shaft, a pair of spring-pressed follower plates carried by the secondary housing section and engageable with the periphery of the cam at diametrically opposite points for dividing the fluid chamber into two half sections; a fluid passage for connecting each one of the fluid chamber sections with one end portion of the cylinder, a housing cover section having one substantially flat exterior face engageable with the second exterior face of the '20 secondary housing section, and means for cod necting together the several housing sections.

'14. A hydraulic vibrator 'of the type defined in "claim 13, further characterized by the opposite substantially flat exterior faces of the secondary housing section each having an endless groove formed therein surrounding the fluid chamber, and a compressible packing ring positioned in each one of said grooves and engageable with the exterior face of the associated housing section to prevent leakage of fluid between said sections.

1 5. A hydraulic vibrator of the type defined in claim 13 further characterized by the main housing section having a fluid reservoir formed therein, duct means for draining fluid leaking along the piston rod and the cam shaft into the reservoir, and valve controlled 'duct means for delivering fluid from the reservoir to each passageway to replace the fluid drained into the reservoir through the first mentioned duct means.

16. A hydraulic vibrator of the type defined in claim 13 further characterized by the main housing section having a fluid by-pass duct formed therein for connecting the two fluid passageways, a tapered valve body operatively positioned relative to one end of said by-pass duct for varying the rate of flow of fluid through said duct, spring means for adjusting the valve body in one direction, and means extending to the outside of the housing for adjusting the valve body in the opposite direction.

.17. A hydraulic vibrator of the type defined in claim 13 further characterized by the main housing section having -'a fluid reservoir formed therein, duct means for draining fluid leaking along the piston rod and the cam shaft into the reservoir, valve controlled duct means for delivering fluid from the reservoir to each passageway that connects a fluid chamber section and a cylinder end portion to replace the fluid drained into the reservoir throughthe first mentioned duct means, the opposite "substantially flat exterior faces of the secondary housing section each having an endless groove formed therein surrounding the fluid chamber, and a compressible packing ring positioned in each one of said grooves and en- 'gageable with the exterior face of the associated housing section to prevent leakage of fluid between said sections.

18. A hydraulic vibrator of the type defined in claim 13 further characterized by the main housing section having a fluid by-pass duct formed therein for connecting the two fluid passageways, a tapered valve body operatively positioned relative to one end of said by-pass duct for varying the rate of flow of fluid through said duct, spring means for adjusting the valve body in one direction, meansextending to the outside of the housing for adjusting the valve body in the opposite direction, the opposite substantially flat exterior faces of the secondary housing section each having an endless groove formed therein surrounding the fluid chamber, and a compressible packing ring positioned in each one of said grooves and engageable "with the exterior face of the associated housing section to prevent leakage of fluid between said sections.

19. A hydraulic vibrator of the type defined in claim 13 further characterized by the main housing section having a fluid reservoir formed therein, duct means for draining fluid leaking along the piston rod and the cam shaft into the reservoir, valve controlled duct means for delivering fluid from the reservoir to eachpassageway that connects a fluid chamber section and a cylinder end portion to replace the fluid drained into n the reservoir through the first mentioned duct, the main housing section further having a fluid by-pass duct formed therein for connecting the two fluid passageways, a tapered valve body operatively positioned relative to one end of said by- 5 justing the Valve body in the opposite direction.

ALBERT MUSSCHOOT.

No references cited.