US3162387A - Hydraulic bowl release for cone crushers - Google Patents

Description

1964 G. SYMONS 3,162,387

HYDRAULIC BOWL RELEASE FOR CONE CRUSHERS Original Filed Oct. 16, 1957 2 Sheets-Sheet l INVENTOR. 10/?! 6. swat 5,

ATTO/P/VZIS.

Dec. 22, 1964 e. SYMONS 3,162,337

HYDRAULIC BOWL RELEASE FOR CONE CRUSHERS Original Filed Oct. 16, 1957 2 Sheets-Sheet 2 INV ENT OR. 10,?! 6. sways,

47 ram 1 5.

United States Patent Ofiiice 3,162,387 Patented Dec. 22, 1964 3,162,387 HYDRAULIC BOWL RELEASE FOR CONE CRUSHERS Loren G. Symons, North Hollywood, Calif, assignor to Nordberg Manufacturing Company, Milwaukee, Wis, a corporation of Wisconsin Original application Oct. 16, 1957, Ser. No. 690,458, now Patent No. 3,019,994, dated Feb. 6, 1962. Divided and this application Nov. 13, 1961, Ser. No. 151,708

17 Claims. (Cl. 241-290) This is a division of my copending application Serial No. 690,458, filed October 16, 1957, now Patent No. 3,019,994, issued February 6, 1962.

The present invention relates to an improvement in cone crusher adjusting and release means, and has for one purpose to provide improved and quickly releasable and yieldable locking means for locking the bowl of a cone crusher against unintended movement in relation to the bowl supporting ring.

Another purpose is to provide means for quickly releasing such locking means and for thereby permitting quick adjustment of the bowl and ring.

Another purpose is to provide improved means for adjusting the bowl of a cone crusher in circumstances where the bowl is in screw-threaded relation to a bowl support by rotating the bowl in relation to the support.

Another purpose is to provide improved releasing means for moving the bowl of a cone crusher when uncrushable material is wedged between bowl and head.

Another purpose is to provide improved control means for controlling the bowl adjusting and bowl releasing means.

Other purposes will appear from time to time in the course of the specification and claims.

I illustrate the invention more or less diagrammatically in the accompanying drawings wherein:

FIGURE 1 is a side elevation of a typical cone crusher;

FIGURE 2 is a vertical radial section, on an enlarged scale, on the line 2-2 of FIGURE 1;

FIGURE 3 is a partial section, with parts broken away, on the line 33 of FIGURE 2; and

FIGURE 4 is a more or less diagrammatic illustration of a varying structure.

Like parts are indicated by like symbols throughout the specification and drawings.

Referring to the drawings, 1 generally illustrates the base flange of the circumferential crusher frame 2. The crusher frame terminates at its upper edge in a flange 3 having outwardly extending aprons 4, The flange 3 has an inner, upwardly conic surface 3a and an outer, generally conic surface 3b. Conforming to and centered on and normally in fixed relation to the flange 3 is the bowl ring or support 5. This support has an inner component 5a which is inwardly screw-threaded as at 5b. It extends outwardly and has a circumferential channel, generally indicated at 50, having portions conforming to the conic faces 3a and 3b of the main frame flange. The ring has also an outward extension or extensions, as at 5d.

In the form of crusher herein shown, the bowl ring 5 is normally held downwardly against the main frame flange 3 by a plurality of springs arranged in clusters. The upper ends of the springs of a particular cluster are positioned within the apron 4 on the flange 3 and abut against the flat lower surface 4a of the main frame flange 3. A lower movable abutment for the spring cluster is indicated at 6. Compressed between the abutment 6 and the lower main frame flange surface 411 are a plurality of springs 7. One spring, indicated at 7a, operates somewhat differently from the remaining springs 7 of the cluster, as will later be seen. Extending through some or all of the springs 7 are spring bolts 8 which may be headed at the top, as at 8a, and which may have securing nuts or other suitable adjustable abutments 8b at their lower end. By adjustment of the nuts 8b, the compression of the springs 7 may be adjusted. Since the bolts extend through suitable apertures in the main frame flange 3 and in the bowl supporting or adjusting ring 5, with the heads 8a abutting against the top of the bowl supporting or adjusting ring, the springs 7 are effective normally, through the abutment 6 and the bolts 8, to hold the ring 5 firmly downwardly against the main frame flange 3 in the position in which the parts are shown in FIGURE 2.

The bowl structure proper is generally indicated at 10. It includes an outer, outwardly screw-threaded cylindrical portion 10a which is in screw-threaded relation with the portion 5a of the adjusting ring 5. It is shown as having an upwardly and inwardly conic portion 10b which may receive a bowl liner 10d and an upwardly and outwardly conic portion 100, upon which any suitable hopper or material guide 11 may be positioned. In order to lock the adjusting ring 5 and the bowl 10 against unintended relative rotation, I provide a threaded locking ring 12, shown as having a downwardly extending skirt 12a. To prevent rotation of the locking ring 12 relative to the adjusting ring 5, they may be keyed together, as at 1211. The connection between the threads may be protected in any suitable way, for example, by the outwardly and downwardly extending hood 11a which may wipe across any suitable oil seal 11b on the locking ring 12 and a seal 11c between the locking ring 12 and the adjusting ring 5. In order to lock the locking ring in place, and to prevent undesired relative rotation of the members 5 and 10, I fined it advantageous to employ the individual springs 7a. I may, for example, employ one spring in each cluster, or I may employ springs in some clusters while omitting such springs in others, depending upon the required locking pressure.

Taking the cluster shown in vertical section in FIG- URE 2 as typical, it will be noted that the spring 7a has a separate washer 14 at its lower end and a separate adjustment or adjusting nut 14a. The abutment 6 is apertured or cut away to permit this. The spring bolt 15 of the spring 7a has the washer 14 adjustably secured by the adjusting nut 14a. The bolt 15 is shown as having an enlargement 15a which enters an appropriate cavity in the lower part of the main frame flange portion 5d. The parts are so proportioned that a slight'upward travel of the spring bolt 15 is permitted before the enlargement 15a contacts the upper end of the cavity in the portion 5d in which it is positioned. Thus, a slight upward movement of the spring bolt 15 ispermitted, without any movement of the adjusting ring 5. I employ this slight upward movement to permit or effect a release of the locking ring 12. The locking ring is normally urged upwardly by locking levers 16, of which the lever shown in FIG- URE 2 is typical. These levers may be fulcrumed on heads 16:: at or adjacent their inner ends which are notched at 16]) to straddle the heads 8a of spring bolts 8. The short end of the lever abuts the bottom of the apron 12a of the locking ring 12. The outer portion of the lever 16 is shown as apertured to permit the passage therethrough of an upward extension 15b of the spring bolt 15. The nut 150, when the spring 7a and the spring bolt 15 are in the position in which they are shown in FIGURE 2, operates to exert a downward pressure on the outer end of the locking lever 16, which exercises a corresponding upward thrust against the apron 12a of When itis desiredto adjust the crusher by imparting a rotation'ofth'e bowl 16in relationto the adjustingringS; j

12." A slight travelis sufficient; and this travel may be obtained, for'example, by. the use of hydraulic. jacks, such as are'shown at20in FIGUREZ; There will preferably be an individual hydraulic jackv for each of the spring bolts each jack: constituting thereby 'a release'forone of the locking levers 16. The details of the jacks do n'ot of themselvesform partof the'present' invention-f It will beundersto od, however, thatthey may be connected by any suitable manifold 21 to' which the interior" ofeach jack is connected by any suitable passagez2l. I prefer to employ conventional spring return jacks sothatt when hydraulic pressure is'admit'tedito the interior: of'the jack, its piston'20a rises,'the spring beingeifective to. depress the piston a when hydraulicpressureis released.

It is thought not necessary to show the" hydraulic system in detail. I ill'ustrate,however; in' diagrammatic form, a valve controllever 25 which, when movedin fone'direcr tion or to one position, permits only sufficient-pressur'e to buildup in the jacks to raisethe spring bolts 15' a ,distance'eifective merely to release the lever 16'. I may, for example, employ-any suitable bypass'valving so, that :the only possible result of moving the lever25: in'the: direction 25a wouldjbe to elevate the. spring bolts 15 as far as they are permitted to rise'without lifting. the bowl adjustingring 5 On the otherhand,when the lever-25isrnoved in the direction"25b or toha 'diflerent p osition,; it';willibe understood thatthe valving is effective to permitsuflicient pressure to buildup in the jacks to elevatethe' adjustment ring 5"-as high'as thesprings 7 and'7a will permit it: to

feet at thelower edge is of the order of: 4 /2 to S-"ihches.

.v 4 r engage any suitable leverage for, applying forceto the locking'ring12, as shown'in-FIGURE 2 The rod" 60 has a bottom plate or abutment'63 which is located substantially below the plate 6. The rod passes through any appropriate aperture 64, centrally located in the plate 6, or so located as-to be on the-general axis ofthe combined spring thrust of the cluster of springs taken as a Whole.

I A separate spring 65, located below the cluster plate or abutment'e, is compressed between it and the bottom plate 63 of the rod 60, and normally urges the rod downwardly the locking ring,12 of FIGURE 2. However, when adjustrise. I may say'that the possible excursion in a. known type of conecrusher having a .cone with. a diameterof17 However, the particular size of the crusher, or the particularpermitted e'xcursion,are not critical-.-. What I-wishto ,beable .t'o do', and can do by the:herein'described structure, is to employ a set of jacks alternatively to release the locking pressure on the locking ring 12, or to elevate thebowl adjustment ring 5; A purpose for elevating'the ring 5'is to permit the interior of the crusher tobe'freed of u'ncrushable material which has stalled the crusherq-i It will'be-understood thatin the normal. use ofthe device, the crushing head, generally indicatedat 30; is gy rated toward and away fr'omthe bowl-1t The crushing takes place as the'result of the'gyration of the head ;within the normally fixed bowl. In the event that uncrushable P e i '50 material, such as a mass of; packedparticles. or a dipper clearance between the bowland head. f The blocking'mament orrelease is necessary, hydraulic pressure is admitted to the. jackiefiT-and urges-its operating piston;67 upwardlyagainst the. bottom plate. or abutment 63 of the rod 60. The piston 67 urges'therod'and the plate'63 upwardly, and'tthe' first contact is with/a downwardly extending abutment or: abutments 68' below'th'e plate 6-. This. elevation isrsufiicient toymove the rod -upwardly far enough tov release: the locking:ring':12 of FIGURE '2, or itsequivalent; The bowl: can then be adjusted. If,

7 however, the hydraulic system. ispoperated: to give the maximummpward movement:of the: jack: elementr67, then the second contact takes place between the rod enlargement 61 and the bowl 'supporting.'ring 5, and; the jack system is effective to lift thawing 5 torthe extent permitted by the full, orssubstantially full, compression of the springs 7: I, FIGURE 4 will; of; course, :be .read as? if the springs 7 were in position and were:compressed between'the'plate 6zand the mainframe flange 1620f FIGURE 2.

The structure'offFIGURE '4 has certain definite advantages: Q. For example, the' thrust'of each jack isibalanced It-willbe, realized that whereas I have described and shown a practical and; operative device, nevertheless,

many changesrmay-be made in? size, shape, number and disposition of parts 'withoutdeparting: from the. spirit of my inventionr I, therefore, wish my description and drawings tojbe taken as in a broad'senseillustrativelor diagrammataicfrathenthan as limitin'g me to my specific disclosure herein. It will be' understood, for example, that Whereas I- have illustrateda crusher in which the springs are. arranged.iniclusters, my system maybeapteri-al then normallypasses'downwardlyfrom th'e cr h,

ing cavity.{ Wlien1the tramp iron or dipper teeth a're'in Volt/ed, and are of too great "a size topass-downwardly through thecavity, they can easily be lifted upwardlyjout of the bowl l In the form [of FIGURE 4; reinstate an ernate V application of force. The disclosure: can be taken some what diagrammatically, fwith" the main frame and top flange-omitted but with a rod element 66 illustrated, which passesupwardly through the bottom; of the spring cluster plate; or abutmenteg and passes upwardly through it has atop enlargementgel fitting. into. anappropriately formed aperture in-thebottomiofthe'abowl supporting ring 5, and also has an upward extension fig which may I find it' desir'able normally-m rely on these springsflln adjusting rings, they may bepufatany other desired or pliediequally iwell to -crushers in which the springsare equally distributed 'infa: single tier aboutthe exterior of the main frame; Whereas Iillustr'atethe jacks 20' as below them'ain frame flange? map-r course, below the desirable location; Lik'ewise; whereas I find' it advantageo'usto apply-thelifting thrust throughthe spring bolts 15 to the adjusting-ring-5;- by: the use of the heads-15:}, I do not wish to be limited to this specific arrangement. It will 'be understood, also, thatwhereas 'l'fin'd it advantageous tohaveeach fof the thrust-membersls or 60 operate initi'allyto 'releaseftheibowl for adjustment; and

' to operate thereafter by a longer travel to elevate the bowl, I may segregate the system andhave'some members operating to release for adjustment and 'other members operating -torelease the bowl. Y

Theuse' and operation ofthe invention are as follows: Stated simply, I employsprings to hold a bowl or bowl support .against' movement; i'ri,--rel'ationto ;'a fmain fframe.

currently employed cone crushers, such springs are used,

' and give adequate service In cone-crushers ,now, on' the market, adjustments, however; are somewhat lengthy and difii'cult-and no means areprovided for, a quick release of a stalled crusher. My invention provides both quick adjustment in normal use and quick release of the crusher, when stalled, by a hydraulic system which normally idles. It operates only when needed. Normally, the springs operate to hold the adjusting ring 5 downwardly against the main frame flange 3, while permitting the necessary yielding safety release to prevent breakage and to permit occasional overloads to pass through. However, when adjustment is desired the movement of the lever 25 in the direction 25a immediately releases the locking ring 12. This permits rotation of the bowl in relation to the adjust-ment ring 5. If the head is gyrated in the proper direction, the immediate result of such a release of the locking ring 12 is to permit the bowl to rotate in response to the movement of the head and the material compressed therebetween. As soon as the desired adjustment is reached, the hydraulic jacks 20 are released by a return of the lever 25 to neutral, and the springs 7a resume their normal locking thrust of the lever 16 against the locking ring 12. If desired, additional locking means may be employed, such as any suitable links or connections, not herein shown, between the bowl 10 and the adjusting ring 5.

I claim:

1. In a gyratory crusher, a circumferential main frame with an outwardly extending flange adjacent its upper edge, a bowl supporting ring tiltably mounted on said flange and movable upwardly therefrom, a bowl mounted on the bowl supporting ring, yielding means for normally holding the bowl supporting ring downwardly against said; flange and substantially fixed in relation tothe main frame while permitting overload release, including a plurality of bowl holding and release springs, their upper ends abutting the lower side of said main frame flange, movable abutments for the lower ends of the springs, and spring bolts passing through apertures in said main frame flange, and connecting said abutments and bowl supporting ring with said springs under compression therebetween, thrust members extending upwardly among the springs through the main frame flange with a surface opposing the bowl supporting ring, and a plurality of hydraulic jacks positioned about the main frame relative to the thrust members so that when the jacks are energized, they apply an upthrust to the thrust members which will be communicated to the bowl supporting ring, thereby raising the bowl to allow the free escape of lodged material.

2. The structure of claim 1 further characterized in that the surface on the thrust members includes an enlargement thereon disposed between the supporting ring and the flange on the main frame.

3 In a gyratory crusher, a circumferential main frame with an outwardly extending flange adjacent its upper edge, an adjustment ring tiltably mounted on said flange and movable upwardly therefrom, a bowl mounted on the adjustment ring, yielding means for normally holding the adjustment ring downwardly against the main frame flange and substantially fixed in relation to the main frame but permitting overload release, a plurality of' thrust rods positioned symmetrically around the main frame extending upwardly through the main frame flange, a lateral surface on each of the thrust rods between the main frame flange and the adjustment ring, and a plurality of hydraulic jacks positioned about the main frame relative to the thrust rods so that when the jacks are energized, they will apply an upthrust to the thrust rods which will be communicated to the adjustment ring by the lateral surfaces on the thrust rods to thereby raise the bowl in order to allow the free escape of lodged material.

4. The structure of claim 3 further characterized in that the lateral surface on the thrust members includes an enlargement thereon between the main frame flange and the adjustment ring.

5. In combination, a gyratory cone crusher having a circumferential main frame with an outwardly extending flange adjacent its upper edge, a bowl supporting ring tiltably mounted on said flange and movable upwardly therefrom, a bowl mounted on the bowl supporting ring, yielding means for normally holding the bowl supporting ring downwardly against said flange and substantially fixed in relation to the main frame while permitting overload release, including a plurality of bowl holding and release springs, their upper ends abutting the lower side of said circumferential main frame flange, movable abutments for the lower ends, and spring bolts passing through apertures in said main frame flange and connecting said abutments and the bowl supporting ring with said springs under compression, said bowl being in screw-threaded relation with the bowl supporting ring whereby, when the bowl is rotated in relation to the ring, its elevation is adjusted, a locking ring in screw-threaded relation with the bowl and means for holding it against rotation in relation to the bowl supporting ring, spring means for normally applying an upward thrust to the locking ring to eliminate thread clearance between the bowl and bowl supporting ring and tending to lock the bowl against rotative adjustment, and means for releasing said spring means and for thereby permitting free rotation of the bowl in relation to the bowl supporting ring.

6. A system of bowl adjustment for a cone crusher having a main frame, a bowl supported for adjustment on the main frame, a crushing head mounted for movement in the main frame and defining a crushing cavity with the bowl, spring means for releasably restraining the bowl against unintended adjustment under a predetermined amount of spring pressure, power means operatively associated with the spring means such that operation thereof overcomes and releases the spring means so that adjustment of the bowl may take place, and additional power means for adjusting the bowl relative to the main frame when the releasable spring means is released.

7. A system of bowl adjustment for a cone crusher having a main frame, a bowl supported for adjustment on the main frame, a crushing head mounted for movement in the main frame and defining a crushing cavity with the bowl, spring means for releasably restraining the bowl against unintended adjustment under a predetermined amount of pressure, and power means operatively associated with the spring means such that the operation thereof compresses and releases the spring means so that adjustment of the bowl may take place.

8. The structure of claim 7 further characterized in that the yielding means for releasably restraining the bowl includes a plurality of springs disposed about the crusher, means for maintaining the springs under compression and effective to exert the thrust of the thus compressedfsprings between the bowl and main frame, and further characterized in that the power means operatively associated with the spring means includes a plurality of hydraulic jacks positioned about the main frame and disposed to apply a compressing thrust to the springs to compress them so that the springs will be overcome and the bowl will be released for adjustment.

9. In a gyratory crusher, a circumferential main frame, a bowl mounted in screw-threaded relationship to the main frame and constructed to be adjusted by rotation thereof, and means for applying a limited, generally axial yielding upthrust to the bowl to releasably restrain it against movementin the main frame but constructed to be released so that free rotative adjustment of the bowl may take place, including a ring in screw-threaded relation with the bowl, means-for holding the ring against rotation in relation to the main frame, and a plurality of springs disposed about the main frame, maintained under compression, and effective between the ring and the main frame to thereby apply a releasable upthrust to the bowl through the ring.

10. The structure of claim 9 further characterized by and including power means for overcoming and compressing the springs to thereby permit free rotation of the bowl in the main frame for adjustment thereof.

11. In a gyratory crusher, a circumferential main frame, 7

' ably restrain the bowl against rotative adjustmentin .the'

bowl supportingring, constructed to be released so that free rotative adjustment of the bowl may .take place, including-meansior applying ayieldable and compressible upthrust to the bowl reactively effective immediately between the bowl and bowl supporting ring to restrain the bowl againstrotative adjustment in the bowl supporting ring, and separate means for eliminating the yieldable upthrust so that .the bowl maybe freely rotated and adjusted.

12..In a hydraulic system. of bowl release for a .cone crusher having a main frame, a bowl supporting ring on said mainframe, a bowl; adjustable on. said ring, and a I to a predetermined excursion of one of more of said spring release normally holding. said ring fixed. on said main frame, butlfoimiedand adapted to, permititsmovev ment in relation to the mainframe when' uncrushable material .is present-in .the crushing cavity, yielding means for normally. holding the. bowl against funintended movement in relation-to thelbowl supporting. ring, a plurality of hydraulic. jacks circumferentially arranged-about the crusher, and thrustmembers mounted about the framej and aligned withand in position .to-be contacted by said jacks, means for releasingthe. yielding means between the bowl: and. the-bowl supporting. ring inirespon'se. to' a predeterminedminimum excursion of. one or.v more of said thrust;members,i.and. means for directing a lifting on'said main frame, ..means. for. looking it against'unin tended adjustingm'ovement, ajspring release normallyholding-saidbowl: fixed ,on saidmain frame butformed and adapted to. permit its, movement. in relation to the thrust members, and meansiforliftingthebowl support ing ring from'the main frame, 1 r

15, In. a hydraulic system of bowl'releasefor' a cone crusher. having a main frame, a bowl audjustably supported on the. main 'frarne a crushing head mounted for'movement'in the main frame and defining a crush ing cavity'with the bowl, means for restraining'the bowl against unintended'adjusting movement, a spring release normally holding; the bowl fixed on themainframe constructedto permit it to move in relation to the main frame when uncru'shable'material is present in the'crushingcavity, and separate power means operatively associatedwith. the restraining means, spring release and bowl such that initial operation of the separate power means releases the restrainingmeans so that the bowl'maybe adjusted and further operation of the separate power means lifts the'bowl to clear uncrushable material.

16. A hydraulic system: of bowl release for a cone crusher having..a main frame, a bowl'supported on the mainframefdr both-adjustment and release, a crushing head mounted for movement in' the main frame and defining a crushing cavity with the'bowl, means for releasably restraining the bowl against unintended adjustment, a spring. release normally holding-the bowl fixed on the frame under pressure and ,constructed' to permit the bowl to release toa release position in relation to themain frame when uncrus'hable material is present in. the crushing cavity, and power means operatively associated with' the releasable. restraining means, the spring release and the, bowl such'thatyinitial operation'thereof releases the releasable restraining means so that adjustment of the'bowl may take place: and further operation moves the bowl to its releaseposition to allow'uncrushable'material to. be cleared from the-crushing cavity.

17; A hydraulic system of bowl adjustmentand' bowl release fora-pone crusher haVing-a'main frame, a bowl supported. on the main frame for both adjustment and release, a crushing head' mounted for movement in the mai frame and defining a crushing cavity with thebowl, means for releasably restraining the bowl against uninitended adjustment, a'spring release normally holding 'the bowl fixed onthe frame under pressure and constructed main frame. when i uncrushableamaterial is present .in. the

crushing cavity, av plurality of hydraulic. jacks circumfer entially arranged .abouLthe. crusher,.means for-releasing the, locking. means :between; the. bowl. and framefiin; responsetoxa predetermined'desserexcursion of one or more of. said, jacks, and means...for.,directing; a.-' l i fting thrust 'against the bowl. in. response to.. aPIedeterrnined greaterrexcursion of. one-ormore of said;jacks. V

'14 In ahydraulic system' of bowlrelease; for. a cone crusher. having aarnain frame aibowl supporting I ring on to permit'the bowl to releaseto a release position in relation .to the main frame when uncrushable' material is present in the crushingvcavityrpower means operatively associated with the; releasable restraining means, the, spring release andthe bowlsuch thatoperation'thereof releases the releasable restraining means so that adjustment of the' bowl may take placegfand movesfthe .bowl

to its release position to allownncrushable 'material't o be cleared'from thecrushing-cavity; and additional power means foradjusting the..bowl relative to the main frame saidmainframe, a bowl adjustablegon .sai'djring', iand-a' spring, release normally holdingsaidiring..fixed on said ment in; relation "to, the mainframe when uncrushable main frame, but formed and .adaptedio :p'e'rmit its movematerial is presentin the crushing cavity,;yieldingfmeans and aligned withfand in 1 position to be contacted by said jacks, means for-releasing the yielding means' be-' tween the bowl and? the. bowLsupporting ring-in response when the releasable restraining means is released. I

R eferences lite'dlin the file-iofi thistpatent l :UmrEn sra rEsPA'rE rs I 2,550,098

, Traylor Apr. .24, 1951 2,680,511.} Bjarme June 8, 1954 2,687,257 Rumpel 'Aug. 24, 1954 2,747,804 Rumpel May29,21956 ,'2,791,'383 Kjelgaard e May. 7, 19.57

;-Feb. 6, 1962

Claims (1)

1. IN A GYRATORY CRUSHER, A CIRCUMFERENTIAL MAIN FRAME WITH AN OUTWARDLY EXTENDING FLANGE ADJACENT ITS UPPER EDGE, A BOWL SUPPORTING RING TILTABLY MOUNTED ON SAID FLANGE AND MOVABLE UPWARDLY THEREFROM, A BOWL MOUNTED ON THE BOWL SUPPORTING RING, YIELDING MEANS FOR NORMALLY HOLDING THE BOWL SUPPORTING RING DOWNWARDLY AGAINST SAID FLANGE AND SUBSTANTIALLY FIXED IN RELATION TO THE MAIN FRAME WHILE PERMITTING OVERLOAD RELEASE, INCLUDING A PLURALITY OF BOWL HOLDING AND RELEASE SPRINGS, THEIR UPPER ENDS ABUTTING THE LOWER SIDE OF SAID MAIN FRAME FLANGE, MOVABLE ABUTMENTS FOR THE LOWER ENDS OF THE SPRINGS, AND SPRING BOLTS PASSING THROUGH APERTURES IN SAID MAIN FRAME FLANGE, AND CONNECTING SAID ABUTMENTS AND BOWL SUPPORT-

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