US2349790A - Gyratory crusher - Google Patents

Description

GYRATORY cRusHER Filed Jan. 30, 1943 w. c. JoHNsoN May r23, 1944.

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Patented May 23, v1944 UNITED STATES PATENT OFFICE GYRA'roRY oRUsHER William C. Johnson, Wauwatosa, Wis., assignor to I Allis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Application January 30, 1943, Serial No. 474,079

Claims. (Cl. 83-10) This invention relates to improvements in the means for supporting the head of a gyratory crusher with automatic release to permit passage of uncrushable substances. The object of Vthe invention is to provide a hydraulic support which will support the Crusher head in a set position against any normal crushing load and allow the head to drop in case pressure in the iluidincreases beyond a predetermined limit with automatic return of the head to its predetermined setting upon clearance of the crushing chamber.

A furtherobject is to provide a mechanical return independent of `high pressure power driven pumps and pump controls. y

A still further object is to provide a device in which the Crusher may be adjusted to any desired Crusher opening independent of hydraulic com trol.

f Theseand further objects which will appear from the following description are` obtained by the mechanism illustrated in the-accompanying `drawings in which:

. Fig. 1 is a more or less diagrammatic vertical sectional view of a crusher embodying the invention; y Y I Fig. 2 is a detailed view to an enlarged scale of the lower section of Fig. 1 showing details .of onepreferred form of spring assembly and adjusting means; I

Fig. 3 is a detailed view to an enlarged scale Lof a modification ofthe lower section of Fig. -1 showing a modified form of spring assembly and adjusting means; and

Fig. 4 is a detail sectionalview of a relief valve indicated in Fig. 1.

Similar numerals refer to similar parts `throughout the several views.

' It fis well known in the prior art to use springs.

to support the crusher head in its proper position against the crushing load, such lsprings .yielding upon excessive pressure between the crusher parts due to uncrushable substances .such as tramp iron or steel between the crushing members. Itis also Well known to use fluid under pressure to supportthe Crusher head under normal crushing pressures, relief :means being rprovided to permit opening of the Crusher upon exceeding a predetermined pressure in the vsupporting fluid. This invention combinesthe ad, vantages of both methods, obtaining an automatic resetting without the disadvantages of the 1purely spring supported head, which requires ex-` tremely strong Vsprings and has avery limited .opening movement, and without the expensive pumps, or accumulator equipment necessary Vto obtain `purely hydraulic head supporting and automatic resetting.

The drawings show the invention as applied to a gyratory Crusher in which a frame is generally indicated by the numeral I. The frame I comprises of an upper section 2 supporting a concave 3 which forms one of thecrushing members.` A 4center section 4 may be the main supporting member and .includes an eccentric bearing 5 in whichthe eccentric 6 Vis mounted for rotation. The crusher shaft 'I` on which are mounted the crusher head 8 with its mantle 80 forms the second crushing member, and is gyrated by the eccentric 6 in a manner well known in the gyratory Crusher art and which forms no part of thepresent invention. The lower section 9 of the frame I comprises a hydraulic cylinder bore I0 in which is mounted with a fluid tight sliding iita head supporting plunger II. On the upper surface of plunger II is carried a step type thrust bearing block I2 which coacts with the end of the gyrating shaft I to support the crusher head ,against the crushing load caused by the reaction .of' the forces developed incrushing material between the head 8 and concave 3 by relativegyrati-on thereof. Plunger I I is held against rotation by a pin I4 mounted in lower'. section 9 and arranged to project into a groove I3'formed` in the surface of the plunger II. Securedl to the upper part of frame section 9 is a thrustbearingl for the eccentric 6. The end of the hydrauliccylinder II] is closed by end capr IS, which is formed with a cup shaped exten sion or spring housing I1, in the end of which is 'coaxially mounted a headfsetting screw I8 provided with a lock nut I9. SectionY 9, plunger I I, and end cap I6 define a uid space 20, having a `single external fluid connection'2l acting as both inlet and outlet. The sections 2, 4, 9 and I6 of the frame .I are -joined in any known suit able manner as,` by studs. 2 2, 24 and 26 and nuts 23,25 and 21. In the fluid vspace 2U between the head setting screw I8 and the plunger II, is located a head setting spring assembly 2B which will be described in detail hereinafter.

A preferred lform of head setting spring assembly 28 is shownin detail in Fig. 2. In this construction a helical coil spring 29 is seated at its opposite lends againsttan upper spring seat ,member .30 and a lower spring'seat member 32. The seat member 3i] is provided with an integral -connecting sleeve 3| extending inside the coils of the spring 29 for a partv ofthe length thereof. .Lowerjseat memberv 32 ris also provided with 4a connecting sleeve 33 extending inside the coils of spring 28. The ends of sleeves 3| and 33 are spacedapart longitudinally of the spring. An adjustable connecting bolt 34 threadedly engages sleeve 33, and slidablyengages sleeve 3| to permit limited relative axial motion of said seat members 39 and 32. In the form shown in Fig. 2, the sleeve 3| kis provided with an internal shoulder 35 which is varranged toengage the head 37 of bolt 34 to limit the separating movement of seats 38 and 32. A lock screw 35 is threaded in seat member 32 and arranged to operatively engage bolt 34 after adjustment of said spring assembly by operation of connecting bolt 34, to retain the same in its adjusted position. Members 38 and 32 with bolt 3'4 form an adjustable lapping ends of springs |29 and 229.

lhousing extension H7 isv of larger diameter to telescoping spring compressor deformable axially to allow further compression of spring 29.

The hydraulic fluid space 29, through passage 2| is connected by parallel conduits 42 and 44 withthe bottom of a hydraulic fluid reservoir 48 provided with a conventional vent 50 and filling plug 5I. n conduit 42 a relief valve 43 is arranged with its high pressure connection 45 in communication with space and its discharge connection 4l in communication with reservoir 48. The internal structure of' a suitable relief valve is sho-wn in Fig. 4 and fully described hereinafter. In conduit 44 a check valve 45 is arranged to permit now only in the direction of space 29.

Plunger may be provided with any known packing as shown at 38 and with sealing grooves as at 40, and the hydraulic cylinder |0 maybe provided with a replaceable liner as shown in Figs. 2 and 3 at'33. Hydraulic fluid may bemaintained at some level as 49 in the reservoir 4B.

As shown in Fig. 1, the crusher may be provided with a dust curtain 52 secured to head 8 and a dust collar 53 secured to center frame section 4, operatively engaged to prevent the passage of dust into the eccentric mechanism 6. Lubricating oil is supplied through a connection 54A and passed through the operating mechanism lubricating the parts and finally discharging at 55.

The eccentric 6 which imparts lthe gyratory motion to the crusher'head 8' may be provided with a ring gear 65 meshing with a beveled 'drive pinion 56 onya shaft 61vrotatably supported in housing 68 on bearings 69. Shaft 61 passes out of theV housing through a packing '70 whichV prevents the escape rof lubricating. oil, and is provided at its exterior end with a drive 'sheave 'H or other known power transmission means.

The relief valve 43 asv shown in Fig. 4', may con'- sist of a valve body 56 providedl with a high pressure or inlet connection 46'and a discharge connection 41. A valve disk 59 is urged by a spring 60 against a valve seat 51, normally closingv off communication from connection 46'to connection 4l. Spring Bil is compressed between the valve disk 59 and a spring seat 6 l', the position of which may be varied by aregulating screw 62 threadedly engaging the end closure cap 58' of theA valve body 56. A lock nut 63 may be jammed against cap 58 to preserve any desired setting ofy regulating screw 62.

In Fig. -3` is shown a modified form of end cap and head setting spring assembly in-which a shorter structure may be obtained by the ingenious use of two springsy |29 and 229 of different diameters. The upper end of' spring |29 and the lower end of spring 2129 are seatedY on upper and lower spring seats |30 and |32, respectively,v similar innearly all respects to spring seats 3|!` and A32 and` provided with connecting-sleeves |3| and |33 and adjustable` connecting boltY |34i In this modl- 735 ication a cup-shaped, floating intermediate spring seat member 4| engages the adjacent over.. Spring accommodate the larger spring 229. The result is a much shorter spring assembly.

The operation of the invention is as follows: Rotative power is supplied to sheave 1| causing rotation of eccentric 6 in' its bearing 5 and gyration of shaft l and head and mantle 8 and 80 with respect to concave 3. Material passing through feed opening 64 to the crushing space l. between mantle .30 and concave 3 is crushed by the relative motion thereof. The crushing pressure developed reacts on the head and may be resolved into a component perpendicular to the axis of shaft 'I which is opposed by eccentric bearing 5, and a component parallel to the axis of shaft 'I which is opposed by pressure on step bearing block I2 supported by hydraulic plunger Assuming that fluid space 20 and the hydraulic system are nlled with a substantially incompressible fluid to level 49, fluid in space 29, and conduits 42 and 44 from passage 2| to relief valve 43 and check valve 45 is trapped and placed under a hydraulic pressure proportional to the crushing pressure by the action ofplunger for the check valve 45 cannot pass fluid towards reservoir 48 and relief valve 43 is regulated by screw 52 so that valve disk 59 will not allow fluid to flow through conduit 42 toward reservoir 4| until the fluid pressure exceeds that caused by reaction on the plunger l of maximum normal crushing pressure and the pressure of spring 69 is overcome. Spring assembly 28 'is set to a predetermined normal length'and the spring is thereby precompressed vto an initial yielding strength preferably substantially more than' that suiiicient to support the weight of plunger Il, bearing block I2, shaft '1, head, and mantle 80, but not sufhcient to withstand the full crushing load. The head setting screw I8 is set to put the head in the desired axial position forV crushing to the desired neness. With a predetermined length and strength of the spring assembly as shown in Figs. 2 and 3, any change in the setting of screw |8 will cause an equivalent change in the axial position of the head 8 relative to concave Sunder rall normal conditions'.

During normal crushing, the reaction on plunger l will act against the trapped uid in space 20 and no substantial displacement of the head downwards or compression ofspring assembly 28 ,can occur'. The l'leadisl thus constrained by the hydraulic support to a position in a predetermined path vof normal crushing movement.`

If, however, a piece of uncrushableY material shouldgcome betweenVv the crushing members 3 and 80, an excessive reaction on plunger Il will cause the fluid pressure in spaceZ and acting on relief valve 43 to exceed that caused by normal crushing. This excessive pressure will act to overcome the pressureA of spring 60 forcing the lvalve disk 59 from its seat and allowing fluid uri-- of the head due to uncrushablesubstance such as tramp iron, the feed to the' crusher at 64 will be stopped by the attendant, and the crusher, gyrating-normally; will become empty after passing theoffending substance. As soon as the load on the crusher drops sufficiently, the energy stored in thespring assembly 28 will be released and. being more than sufficient to return the head to its predetermined setting, will cause the plunger H and head 8 to resume their proper setpositions with spring assembly 28 extended to its full predetermined length and initial precompression. The action of spring assembly 28 in causing the plunger Il to move upwards to its set position will cause a fluid pressure drop in space 20, whereupon check valve 45 will opento permit fluid to flow from reservoir 48 through conduit 44 to replace the fluid forced out of space 20 by the excessive pressure on plunger Il. The crusher will thus `be returned to its proper set po sition and crushing may be resumed. v Any lowering of the head 8 due to possible leakage of fluid from space 2D during operation ofthe crusher will be corrected by the spring assembly whenever the crushing load drops suiciently so that the total load on' the plunger is less than the initial strength of spring assembly 28 and the fluid lost will be replaced from reservoir 48 bythe upward motion of plunger I l. Restoration of the head is entirely automatic, being accomplished by the spring assembly 28 independently of any fluid pumping apparatus or controls; Hydraulic support by a trapped body of fluid gives steady support to the head, yieldable only upon opening of relief valve 43. This mechanism will continue to function without attention otherv than control of feed to the crusher after once being adjusted to the proper setting by adjusting screw I8. Adjustment for maximum normal crushing pressure by regulating screw 62 on relief valve 43 is simple and dependable. Once spring assembly 28 has been set to the desired precompression or initial yielding strength, a change in the setting of the crusher by operation of adjusting screw I8 will not alter the normal length of the said spring assembly.

In case a simple spring as shown in Fig. 1 at 28 without the precompressing, telescoping seat arrangements of Figs. 2 and 3 is used, the length of the spring assembly will be determined by the scale of the spring and the Weight of the supported parts, under no load conditions, and no adjustment of limited spring assembly length will be possible, otherwise the action is the same except that there will be no available excess of spring force, over that required to balance the supported parts, to overcome any abnormal resistance of resetting of the head under no load conditions.

It will be understood that the drawings and description represent a preferred embodiment of the invention in a particular type of crusher, and that the invention may, with obvious changes, be used in crushers of different types as will be readily apparent to persons skilled in the art. The scope of inventionis intended to include Vsuch modifications and equivalents as may occur to persons skilled in the art and come within the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In a crusher comprising relatively movable crushing members, means to impart a normal relative crushing movement to said members, support means including normally closed expansible chamber hydraulic means supporting one of said members in relation to the other and normally constraining said one member to a position in a predetermined path of normal relative crushing movement, said support means being so constructed and arranged that the pressure in said hydraulic expansible chamber is proportional to the crushing pressure on said members, fluid pressurerelief means responsive to abnormal pressure caused by uncrushable substance between said members to allow fluid discharge from and contraction of said chamber and abnormal relative movement of said members to avoid excessive pressure, a fluid reservoir, conduit means connecting said reservoir with said hydraulic chamber, means in said conduit permitting fluid flowv from said reservoir to said chamber and preventing reverse ilow, elastic means deformable by abnormal movement of said members and said hydraulic chamber means and tending to urge said members and said expansible chamber means towards their predetermined normal positions and causing Said expansible chamber means to draw in fluid to replace fluid discharged therefrom. i

2. In a crusher comprising relatively movable crushing members, means to impart a normal relative crushing movement to said members, support means including normally closed expansible chamber hydraulic means supporting one of said members in relation to the other and normally constraining said one member to a position in a predetermined path of normal relative crushing movement, said support, means being so constructed and arranged that the pressure in said hydraulic expansible chamber is, proportional to the crushing pressure on said members, fluid pressure relief means responsive to abnormal pressure caused by uncrushable substance between said members to allow fluid discharge from and contraction of said chamber and abnormal relative movementVo-f said members to avoid excessive pressure, a fluid reservoir, conduit means connecting said reservoir with said hydraulic chamber, means in said conduit permitting fluid flow from said reservoir to said chamber and preventing reverse flow, elastic means deformable by abnormal movement of said members and said hydraulic chamber means and tendingto urge said members and said expansible chamber means towards their predetermined normal positions and causing said expansible chamber means to draw in fluid to replace fluid discharged therefrom, said elastic means comprising a spring assembly having a spring and means engaging the ends of said spring and constraining said spring to a predetermined normal length, said assembly being deformable in length by pressure in excess of a predetermined amount, said spring urging said assembly to assume its normal predetermined length with sufficient force to cause said crushing members to resume their normal positions upon removal of said crushing pressure.

3. In a crusher comprising relatively movable crushing members, means to impart a normal relative crushing movement to said members, support means including normally closed expansible chamber hydraulic means supporting one of said members in relation to the other and normally constraining said one member to a position in a predetermined path of normal relaltive crushing movement, said support means being so constructed and arranged that the pressure in said hydraulic expansible chamber i-s pro- ,abnormal portional to the crushing pressure on said members, fluid pressurefrel'ief means Yresponsive to abn'ormal pressure caused by un'crushable substance between said members to allow fluid discharge from and contraction of said chamber 'and abnormal relative movement 'of said members to avoid excessive pressure, a iluid reservoir, conduit means connecting said reservoir with said hydraulic chamber, means in said conduit permitting fluid flow from said reservoir to said 'chamber and preventing reverse flow, elastic means deformable by abnormal movement of said members and said hydraulic chamber means and tending to urge said members and said expansible chamber means towards their predetermined normal-'positions and causing said expansible rchamber means to draw in Iiuid to replace fluid discharged therefrom, said elastic means comprising afspring` assembly having a spring and means engaging the ends of said spring and constraining saidspring toapredetermined normal length, said assembly being deformable in length by pressure in excess of a predetermined amount, said spring urgingsaid assembly to assume its normal predetermined length with suilcient force to cause said crushing members to resume their normal positions upon removal of said `crushing pressure, in which the position of one end of said elastic means relative to one of v.said crushing members under normal conditions determines the normal positions of said crushing ,y members and v.said hydraulic supporting means,

and'means to adjust the position of said one of said elastic means relative to said one of said crushing members.

4. In a/'crus'her comprising relatively movable crushing members, means to impart a normal relative crushing movement to said members, support means including normally closed expansiblechamber hydraulic means supporting one -of said members in relation to the other and normally constraining said one member to a position in a predetermined path of normal relative crushing movement, said support means being so constructed and arranged that the pressure in -said hydraulic expansiblechamber is proportionalto the crushing pressure on said members, fluid pressure relief means responsive to abnormal pressure caused by uncrushable substance between-said members to allow fluid discharge from and contraction of said chamber and abnormal relative movement of said members to avoid excessive pressure, a fluid reservoir, conduit means connecting saidv reservoir with said hydraulic chamber, means in said conduit permitting fluid ow from said reservoir to said chamber and preventing reverse noti/,elastic means deformable by .movement of said members and contracting of said hydraulic chamber means and tending to urge said members and said expansible chamber means towards their predetermined normal positions and causing vsaid expansible chamber means to draw in fluid to replace iluid discharged therefrom, said elastic means being entirely within said expansible chamber means.

'5j In a gyratory ,crushen a concave, a frame 'work supporting said concave, a gyratory shaft and Crusher head, mounting means on said frame 4work for said shaft and head including means. to`

gyrate said shaft andwhead about the axis of said concave, said mounting means comprising hydraulic means supporting said shaft in a predetermined axial position relative to said concave lagainst axial displacement by force caused by relative motion of said head `and concave to'crush vmeans to adjust the axial material therebetween, said hydraulic means being yieldable only to abnormal forcescaused -by uncrushable material to permit axial movement of said shaft and head, elastic means associated with saidr hydraulic means and deformable by said yielding thereof to return said vhydraulic means and said shaft to normal position upon removal of said uncrushable material, said hydraulic means comprising a plunger and a cylinder, said cylinder having a supply and discharge outlet normally closed by a supply check valve and a relief valve, said elastic means comprising a spring within said cylinder acting to return said plunger and said cylinder to predetermined relative position after relative axial displacement thereof.

6.- In a gyratory Crusher, a concave, a frame work supporting said concave, a gyratory shaft and Crusher head, mounting means on said frame Work fo-r said shaft and head including means to gyrate said shaft and head about the axis of said concave, said mounting means comprising hydraulic means supporting said shaft in a predetermined axial position relative to said concave against axial displacement by force caused by relative motion of said head and concave to crush material therebetween, said hydraulic means being yieldable only to abnormal forces caused by uncrushable material to permit axial movement of said shaft and head, elastic means associated with said hydraulic means and deformable by said yielding thereof to return said hydraulic means and said shaft to normal position upon removal of said uncrushable material, said hydraulic means comprising a plunger and a cylinder, said cylinder having a supply and discharge out` let normally closed by a supply check `valve and a relief valve, said elastic means'comprising' a spring within said cylinder acting to return said plunger and said cylinder to predetermined relative position after relative axial displacement thereof, and means to adjust said spring means to predetermined initial yielding strength and predetermined normal axial length.

7. ln a gyratory crus-her, av concave, a frame work supporting said concave, a gyratory shaft and Crusher head, mounting means on said frame work for said shaft and head lincluding means to gyrate said shaft and head about the axis of said concave, said mounting means comprising hydraulic means supporting said shaft in a predetermined axial position relative to said concave against axial displacement by force caused by relative motion of said head and concave to crush material therebetween, said hydraulic means being yieldable only to abnormal forces caused by uncrushable material to permit axial movement of .said shaft and head, elastic means associated with said hydraulic means and deformable by said yielding thereof to return said hydraulic means and said shaft to normal position upon removal of said uncrushable material, said hydraulic means comprising a plunger and a, cylinder, said cylinder having a supply and discharge outlet normally closed by a supply check valve and a relief valve, said elastic means comprising a spring within said cylinder acting to return said plunger and said cylinder to predetermined relative position after relative axial displacement thereof, means to adjust said spring means to predetermined initial yielding strength and predetermined normal axial length, and l position of one end of said spring means thereby to determine the vnormal axial position of said shaft rand head.

"8-.In 'a crusher, yi'eldable hydraulic bearing support means comprising a contractable hydraulic fluid containing means of normal predetermined volume, elastic means of positively limited .length deformable by contraction of said fluid containing means and active when deformed tocause expansion of said fluid containing means to said predetermined volume, a discharge and intake opening in said containing means, relief valve means connected Ywith said opening to permit discharge of uid and contraction of said container under abnormal pressure, check valve means connected with said opening preventing discharge of iiuid therefrom, uid supply means connected with said check valve means, said check valve permitting intake of fluid from said fluid supply means upon expansion ofv said container, said elastic means comprising an assembly having a spring, a telescoping spring compressor, and means to adjust said compressor to precompress said spring to a predetermined initial tension and positively limit said assembly tofa' 'predetermined normal length.

l*9. In a crusher, yieldable hydraulic bearing support means comprising a contractable hyf draulic fluid containing means of normal predetermined volume, elastic means of positively limitedlength deformable by contraction of said fluid containing means and active when deformed to cause expansion of said iluid containing means l 1 tofsaid predetermined volume, a discharge and intake opening in said containing means," relief valve means connected with said opening to permitdischarge of fluid and contraction of said container under abnormal pressure, checkl valve means "connected with said opening preventing discharge of iluid therefrom, fluid supply means connected with said check valve means, said check valve permitting intake of fluid from said fluid supply means upon expansion of said container, said elastic means comprising an assembly having a spring, a telescoping spring compressor, and means to adjust said compressor to precompress said spring to a predetermined initial tension and positively limit said assembly to a predetermined normal length, means on said :fluid containing means to adjust the position of said elastic assembly relative thereto to vary the predetermined volume of said fluid container,

said bearing support being movable and having its normal position determined by the volume of said hydraulic means.

10. In a gyratory Crusher, a Crusher body, a concave supported in said body, a crushing head rigidly connected said bodi7 for gyratory and axial motion relative to the axis of said concave, a bearing support member capable of movement relative to said body to determine the axial position of said shaft and head relative to said concave, said support member comprising a plunger, a cylinder rigidly connected to said body in axial alinement with said concave, said cylinder engaging said plunger in fluid sealing engagement, means comprising a volume of substantially incompressible fluid in said cylinder to determine the axial position of said plunger and resist axial displacement thereof in a direction to reduce the volume established b v said plunger and cylinder, a fluid supply and discharge opening on said cylinder normally closed by a pressure responsive means permitting discharge of fluid above a predetermined Ipressure, a check valve permitting supply of fluid to said cylinder but preventing discharge therefrom, a fluid supply reservoir and a conduit conto a shaft means, mounted in :t

into said cylinder from said reservoir. y

1l. In a gyratory crusher, a crusher body, a

concave supported in said body, a crushing head rigidly connected to a shaft means, mounted in said body for gyratory and axial motion relative to the axis of said concave, a bearing support member capable of movement relative-.to saidl body to determine the axial positionof said shaft.

and head relative to said concave, said support member comprising e, plunger, a cylinder rigidly connected to said body inaxial alinement with said concave, said cylinder engaging said plungerl in fluid sealing engagement, means. comprising a volume of substantially incompressible fluid in said cylinder to determine the axial position` of said plunger `and resist axial displacement thereof vin a direction to reduce the volume established by said plunger and cylinder, a fluid supply and discharge opening on `said cylinder normally closed by a pressure responsive means permitting discharge of iluid above a `predetermined pres-i sure, a check valve permitting supply of fluid toA said cylinder butpreventing discharge therefrom, a uid supply reservoir and a conduit connecting said reservoir to said check valve, elastic means of vaxial displacement of said plunger in said'c-ylinder, said' elastic means when deformedV acting' to urge said plunger towards its predetermined axial position relative to said cylinder thereby causing fluidto be drawn into said cylinder from said reservoir, adjusting means operatively connected with the said cylinder and axially supporting said elastic means for adjusting the normal axial position of said elastic means, said plunger and said shaft.

l2. In a Crusher having relativelyY movable crushing members, precompressed elastic means operatively engaging said members to determine the normal relative position of said members under no load conditions, normally closed hydraulic means of predetermined volume operatively engaging said members to resist relative displacementthereof under maximum normal crushing load, means to permit discharge of fluid from and reduction in volume of said normally closed hydraulic means when said load exceeds said maximum normal crushing load, said elastic means urging said hydraulic means to resume said predetermined normal volume, a source of fluid, and means to automatically connect said source of fluid to said hydraulic means for now of fluid to said hydraulic means in response to an increase in volume of said hydraulic means.

13. A yieldable bearing support comprising a hydraulic means having a predetermined normal volume, said hydraulic means being yieldable under predetermined excessive pressure by discharge of uid therefrom, a uid supply reservoir, check valve means permitting flow of fluid from said supply reservoir to said hydraulic means and preventing reverse flow at least at a lpressure below said predetermined pressure, and means operatively connected with said hydraulic means to urge said hydraulic means tc resume its predetermined normal volume after a yielding movement, said hydraulic means upon such resumption of normal volume acting to suck in fluid to replace fluid discharged therefrom,

saidl hydraulic means comprising relatively movable plunger and cylinder means defining a closed hydraulic 'uid chamber, said means to urge said hydraulic means toresume its normal predetermined volume comprising a spring assembly ax.- ially arranged Within said hydraulic iluid chamber and operatively engaging said plunger and cylinder means, said assembly including deformable means lpositively limiting the axial length and initial yielding strength of said assembly.

14. A yieldable bearing support comprising a hydraulic means having a predetermined normal volume, said hydraulic means being yieldable under predetermined excessive pressure by discharge of fluid therefrom, a fluid supply reservoir, check Valve means permitting flow of fluid from said supply reservoir to said hydraulic means and preventing reverse oW at least at a pressure below said predetermined pressure, and means operatively connected with said hydraulic means to urge said hydraulic means to resume'its predetermined normal volume after a yielding movement, said hydraulic means upon such resumption of normal volume acting to suck in fluid to replace fluid discharged therefrom, said hydraulic means comprising relatively movable plunger and cylinder means dening a closed hydraulic fluid chamber, said means to urge said hydraulic means to resume its normal predetermined volume comprising a spring assembly axkially arranged Within said hydraulic uid chamber and operatively engaging said plunger and cylinder means, said assembly including deformable means positivelyy limiting the axial length and initial yielding strength of said assembly, adjusting means operatively engaging a part of said hydraulic means and said spring assembly to adjust the relative predetermined axial positions of said plunger and cylinder.

15. A yieldable bearing support comprising a hydraulic means having a predetermined normal volume, said hydraulic means being yieldable under predetermined excessive pressure by discharge of fluid therefrom, a fluid supply reservoir, check valve means permitting ilow of uid from said supply reservoir to said hydraulic means and preventing reverse flow at least at a pressure below said predetermined pressure, and means operatively connected with said hydraulic means to urge said hydraulic means to resume its predetermined normal volume after a yielding movement, said hydraulic means upon such resumption of normal volume acting to suck in lluid to replace iluid discharged therefrom, said hydraulic means comprising relatively movable plunger and cylinder means defining a closed hydraulic fluid chamber, said means to urge said hydraulic means to resume its normal predetermined volume comprising a spring assembly axially arranged Within said hydraulic fluid chamber and operatively engaging said plunger and cylinder means, said assembly including deformable means positively limiting the axial length and initial yielding strength of said assembly, adjusting means operatively engaging a part of said hydraulic means and said spring assembly to adjust the relative predetermined axial positions of said plunger and cylinder, said adjusting means being ofsullicient strength to support the maximum deformed pressure of said spring assembly, and said initial yielding strength oi said spring assembly being at least sulcient to support the no-load weight on said bearing support.

WILLIAM C. JOHNSON.

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