US2012092A - Ore reduction furnace and condensing chamber - Google Patents

Description

Aug. 20, 1935. A, A. ANDERsbN ORE REDUCTION FURNACE AND CONDENSING CHAMBER Filed Nov. 15, 1955 2 SheetsSheet 1 I INVENTOR RNEY 0, 1935. A. A. ANDERSON 2,012,092

ORE REDUCTION FURNACE AND 'CONDENSING CHAMBER Filed Nov. 13, 1953 2 Sheets-Sheet 2 AT RNEY Patented Aug. 20,

I UNITED" sT-ArE-s can REDUCTION FURNACE AND e CONDENSING CHAMBER Almer A. Anderson, Seattle, Wash., assignor of "one-half to Wm. Phelps Totten, Seattle, Wash Application November 13, 1933, serial No. 697,803

1 Claims. (01526 -18) I Myrinvention relates to an ore reduction and vaporizing furnace meanscombined with an integrally constructed condensing means, whereby most: ,metals and values "may be extracted from i most ores by volatilization thereof in an enclosed crucible furnace-and reduced by selective condensation in connected and co-ordinating condensing apparatus. The ineans'provides separate control andelimination of combustion gases'and ore vapors. Combustion chambersconsist of rectangular helical ascending passages through spe-' cial firebrick which confine combustion flames against the crucible exterior, fortify the crucible,

with spiral partitions and'assist in insulating L cible and exhausting separately to stacks.

4 the crucible from the furnace shell; each of two or more, such described heat lanes leading combustion flames from separate pressure burner nozzles, within: the base ofi the furnacein multipleicircuitous inclined courses about the cru- Ore vapors are provided with a sealed perpendicular passage from crucible through a throat, corresponding' in size and shape to the rim of the cruciblainto an overhead reservoir or hood which is built stationary upon the .main frame casting orhorse. .The crucible is suspended in and as a part of a tiltingcradle, The crucible is designed in elongated, narrow V or flat trough shape to' facilitate rapid and thorough penetrationof heat qto contents when upright, rapid dumping of" ganguewhen fully tilted and rapid charging when partially. tilted. The furnace shell of'steelycon j taining the crucib1e,'firebrick, combustion appa-" ratus and other devices shown. constitutes a cradle and is suspended upon suitable trunnions 7 extending from each end thereof and mounted iI'l bBIiIIgS in the end standards-of the stationmy main frame casting at points measured to make the cradlebalance its sloping top surface- 40 away from, the apertured under surfaces of the flush against, and" also permit'tilting same fully stationary'base of an overhead vapor reservoir. The cradle may, by power applied to an attached wheel "gear, operated from a removed source by chain or belt, be tilted through an arc sufficient. for gravity dumping of gangue from cruciblefand' charging crucible with ores. When upright, the furnace, crucible top, combustion exhaust and other operating features are by: virtue of reciprocally inclined planes of contact sealed as ahnit to co-incident surfaces, parts and aperturesin the overhead hood and stationary frame respeo tively; the cradle is closed when upright andin such closed position the crucible chamber is'firrnly values.

with sprocket chain removed. I

sealed to the condensing units and ready forithe vaporizing operation. J g i I a The generalobjectincludes special objects in' the condensing means wherein ore vapors are carried automaticallyby heat and vaporexpaniv sion pressure generated in the crucible lIltOITGSG ervoirs, passages and chambers designed consecutively to facilitate 'promptand full reduction of the metal and value content to commercial. or

solid form particularly by acombinationofgconstruction and preparationas hereinafter shown'z designedto reduce internal pressure byyrelease of the vapors into expanded areas, to disrupt ,the

column ror internal structure,- of the vapors, by sudden interruption and reversal of direction of fiowfto cool-vapor passageways through water filled tanks "in which temperatures may be .regu-g lated and sharply reduced, to induce in partic:-:

ular metals'such as golda'molecular 1 attraction and adhesion {to-surfaces washedor treated Ewith a preparation of :Silicaor other corrosion' resisting material and to filter vapors 1 in 1 perpendicg.

.ular passages :through napp'ed wool orlasbestos: strands hung between vertical'bafile-platest *The' object contemplates integral construction and co-j.

operation of all the foregoing, but permitsoptional selectionofiportions to meet specialrequirementsl The object includes permissibleauxiliary or alter-* native use of the: furnacesfor v reduction" and re-[ covery of metals and values inmolten or residuary.

' form; The invention contemplates adequate Lac-1 cess to every part; of the; condensing Vmeans for.

full and easy removal of reduced metals and- Other objects oi -the invention; more specific:

than-those referred to above, willbei'n; part 'o'bvi ous and in part pointed out fin the following description of the elements,-icombinations; ar'-'j rangements of parts and application of princi-fples constituting theinventioniand the scopeof protection will be indicated. in the appended claims. The accompanying drawingsareby ref-' erence made a part of this specification and show" a preferredideal'and illustrative operating 'for'm' of the invention, wherein:

Figure 2 is a view upon line 2 2'or ri ufe r Figure3 is a sectionupon the line 3-3 of Fig ure 2 with the supporting framework removedi 1 Figurelis the end elevation of the evaporatingfurnace and condensing dome unit. 4'

. "Figure 4 is a longitudinal section of the "second; a 3

stage or return tube condensed.

' Figure 51s a cross-section of' the vertical filter or*colle,otingtank. f i

are provided with bearings 9 in which are supported the trunnions ID of the cradle represented in its entirety by reference numeral I I which will be described later. I2 are the bearing caps and are secured in place by bolts l3. Extending upwardly from the shelf 8 are stanchions l4 supporting'the condensing dome represented in I its entirety by I5. I6 is a rectangular neck or passage connecting opening 8a with-dome I5. I! (Figure 3) is a deflector extending the'full length of the dome. The condensing dome I5 is provided with an openingwhich may be tightly closed by cover l8 hinged at l9 and latched by means of eye bolts 20 pivoted to brackets 2! by means of pin 2Zand adapted to swing into slots 23 in lugs 24 (Figure 2) cast in the main body of the dome. 25 are nuts by means of which the latching arrangement may be tightly drawn up. 26 is a manifold consisting of two branches as shown in Figure 2 and connecting to a, common outlet 21. The entire interior of dome l5 with neck I6 is coated with athin layer of silica or fireclay.

' The cradle II is in general a rectangular metal box, preferably steel consisting of bottom 28,"

3| of the cradle and the undersur face of shelf' 8 may be sealed by any approved form of gasket or fire resisting material.

The interior of cradle -I l is first lined with an' approved insulating material 33 such as asbestos The cradle is' next lined with aor the like. 7 fireproof brick 34 so as to form a pocket to receive the crucible 35. The inner face or surface I of this pocket is provided with two passages or grooves 36 and 31. Passage 36 commences at the lower right hand end (Figure 2) of cradle H as at 38 (Figures 2 and 3) and winds upwardly in the form of a rectangular helix and terminates at the upper left hand end of the cradle as shown at 39. Passage 3'! commences in'the lower corner opposite 38 as'at and winds helically upward in a like manner and terminates at 4! where it joins with passage;39, the junction terminating in a single tube 42 (Figure 2). The

" beginning 38 and 40 of passages 36'and 31 rebe stopped up by removable firebrick plugs 44 secured to covers 45 which are secured to the sides of the cradle by means of bolts and wing nuts 46 and 41 respectively.- The end 38 of passage 31 is provided with a tube 48 which extends through the end of the cradle The end of passage 31 is provided with a similar tube 49.

5|] and 5| are oil burners provided with flanges by means of which they are secured to the end frame 1 by screws 52 (Fig. l and Fi 2). The

mouths or outlets of these oil burners are located I so as to register with tubes 48 and 49 when the cradle is in its normal upright position. 35 is a crucible with sides tapered downwards and rounded at the bottom so as to fit snugly into the pocket formed by the fire brick lining. The bottom of the crucible slopes towards each end as shown at 53 (Fig.2) and terminates in spout 54 which registers with opening 55 in the cradle. Openings 55 are closed by shutters 55 pivoted as at 57 (Fig. l) and provided with a handle 58 (Figures 1 and 2) 59 are small spouts or troughs immediately below openings 55 in the cradle II and 60 are other troughs which may be cast integral with the frame and located directly below spouts 59.

To one trunnion of thecradle is rigidly secured a sprocket wheel SI. 62 is a pedestal forked at its upper end and provided with bearings 63 in which rests a shaft 64 to which is keyed a sprocket 65 and ratchet wheel 65'. 5'! is a bearing capsecured in place. by means of bolt 68. This bearing cap is providedwith a small lug 69 to which is pivoted a pawl Iii by means of pin H and adapted to engage the-ratchet wheel 55. To the opposite side of sprocket wheel 65 may be secured another ratchet wheel (not shown) andpawl arrangement adapted ,towork in the opposite direction. (Dnepawl of course is disengaged when the other is in operation; Passing over sprocket wheel 6| and 66 is a sprocket chain 12.

To one end 'of shaft 64 is secured a crank 13.

Secured to the frame and registering with tube 22 (Figure 2) is an exhaust pipe. ;14.the inner end of which is provided with a loosely fitted sleeve 15' which may :beslipped over the end of tube 42 when cradle'is'upright and furnace in operation.

The return tube condenser consists of a main body or shell '13 constructed of any suitable material such as Wood or metal and fitted with intake pipe 14' and outlet pipe 15 to permit circulation of acooling medium such as water. passing through the condenser making tight joints where they penetrate the shell. The protruding ends are connected by return bends I! so as to form a continuous passage for the gases. Y The interior diameter of the tubes and the interior diameter of the return ends are the same so as to prevent any shoulders. The exterior ends of the condenser tubes i6 and the interior ends of the returnbends are machined soas to'form gas tight joints. 7 The ends of the return bends 7? are provided with flanges 13 (Figure 6) which. are drilled to receive studs '59 (Figure 4) -which' are secured to the condenser shell 13.

The studs are provided with wing nuts 35 so the returned ends may be drawn uptight on the ends of the tubes and also facilitate ,easy removing. The tubes may pass through the shell in any desired manner such as vertically or. horizontally. The interior surface of tube 18 and return bends T! are coated with a thin layer of silica or fireclay.

89a is a thermometer by which the temperature of the cooling medium can be determined.

The vertical filterconsists of a casing 8| provided with suitableopenings 82 and 83 to faciliita te easy cleaning and removing'of inner parts. These openings are closed by easily removable covers 84 and 85 respectively. The covers may be held in place by studs and wing nuts as in 16 are tubes.

dic ated: 86 {and 8'! arevertical .bafiles; considere;

ably; shorterrthan thecheight of the casingaill and. secured? andljoined a1ternate1y .with the top and the bottom of. the. easingaas. showni (Figure 5);. Y

and; extending; .fromside to. -side .making;tight joints, therewith forming a .;number .of; ;;vertica 1.

0nd; duet; communicating. with -eaeh' other shown, andthe tops of thesecendyandthird cemg;

municatingwithi each other so 'asito-iorm' a gen tinuous passage: for; .7 the gases jyfrom an,;inlet;

The-numbers ofibaffles and: ductsrmay ,be: increased 7 to: any. desiredmurnbeh to suit 1 conditions-.11

Suspended in eachxduct: 88. ironic-racks; 9], are

banks of: hinted-asbestos ,ortwool strands ofilength,

' shownandof sufficient numhertovfill the entire;-

duct and. packed closely 'enough. t0-,::cause;'.t'he

desiredi'filtering' of: the gases to recoven; the :re-.=

mainingxvalues before. the gases-are exhaustedvtm therzatmosphere. through pipe 90;: ;'Ihe outlet? 21-1601? vconclensi'ng dome I 5. (Figure 3) connects with the first "or inlet: 16a .-of the Lfirst condenser;

25 tube-11 6 I of the return tube condenser. (Figureein 'Ihe outletiof the return tube condenser: tubes" arejeonnected with the in1et'89 of the filtenbysmeans" of ea pipe-92; 'the inner. surface: of-.which-; is also co'ated-with afthinlayer. offsilica. The.- above eonnections causing a. continuous passage forthe gases fromthe crucible throughT-the' dome; condenser through' the return't'ube condenser 'andl finally-through 'the:filter' (Figure 5) to: the atmos "'I'he'--method ofoperationiisas. follows Bawl' is lifted an'd' crank [3 turned causing thesprockee 65 to turn which in turn ,rotates sprocket, 6 I by means *of 'chai n 12-50 asto 'tilt' the cradleleon-l' tainin thecrueible in the direction indicatedby arrow. The cradle is. tilted-sufficiently far to 5. give aecess to loadingthe" crucible with the: ores.

Y to"bre duced and the-cradle returned'to its up i l5, The"-"vapbrswhich' arenot'fcondensednvillh ,righti pos'itionz" "In starting the fire the eoverslliv of the cradle (Fig. 2 and Fig; 3) are first r'emovedl" and the firsstarted' directing" the" flames into the spiralpassages 3B and'31.-= The object for rem0v';

mg theeovers 45 is to eliminate the-danger from explosions'which'may b e causedlby an aeoumulation'of'oil'dr gases before'sufiieient clraft'dr proper" fire is attained; "After fireare secured in place-. r a U I When-' suffieient ternperaturehas been rea'ehed the Ores in the erue'ihlewill'inelt "and-"finally "we; porize, the .hot ore vapors passing Up' thr ughQ neck l6 into do'rne condenser 15 where theffirst condensation takesiplace or, where the metal vapors 'which will ppmens'eat the highest tem? perature "will be foondensed' depositing the' metal Onthejbafile ll or'the interio-rlin ing in domei pass throughpass'ag'e 2! (Figure 3)-into return tube pondenser F' (Fi'gure "4-) where -more nietals will be 'condensed'out; the gr'eatest amount be-.

a variedfby changing the temperatureg'ofithe cool? iiig deposited in'thereturnedbendsllif whereith direetion of how is interrupted or changed f Thl.

condensing temperature: in the tubes- 16 m ing: medium passe'd' through the 'c'onder' ser or temperature "being read *by thermometer; ;.80a..

; The metals or values requiring'a lower tempera-z tureto' condense will pass ongth'rough. pipeaBZ? into the i filter (FiguregB) Where i the remaining} values will be deposited on the stranded-asbestos. or-z'wool banks in ducts 8.8: rAfter the heat: is

;finished i;the -values onijdepositmare rem'ovedii the covers?" p-the gdome cendenserg by; opening eeyern rem ved by io enin swi e-nutsa 0: and remo e? ing the return bends 11 from which theyzvaluesg I canzbefeasily remoyejcland given .full access for E" remoying the .waluesj deposited-in; the; straight} v tubes- 1% ;-The--fina1. values parekgremo'yed; from? E esfiaz. through-:;:the=-qp i smflyori 8.3 ymremeving thestranded asbestps or wool:

w V will notjvolatiliz runder n eri;na- 1g=heat s.,in;,-thez crucible; but.sink-.:to .pthe' bottompi--the-crucible; maybe drawn off thru hout fik tt e bet oma d le e d a euezare tnit,aatttn mig. tte Y .li as hasflma y cha es may-telnet;

thedimensionsand eonstruetion;of any and allf part without: (Eventing .fromqcthm spiritl and;

seem et'..-theinvention 1as-defined-in the :fol-lowr ing plaims; it is intendedthat fall matter,.--e0n-u tained l3! illustrative, and not in a; limiting sense; .=Yarious3 changesin,materiah. size, shapefirelation- ,"construction and arrangement; of parts: may be-Erer sorted to by -thoseskilled in" the; art; without'de aii e irem t piritz f yi ve tion ori-any:- 0 'subiQ n d l ims: .1; I i fieiereneeis hereby. made. to my previous; ape.

plicatlon ion Letters; Patent; under: ;Ser-ial *Nozi" 624-;986, filed in the United States Patent Office; on July 27th, 1932, for an Ore evaporating-iurnacew 5 :Having thus; described my --invention, what? I claim .as. new and desire tosecure by Letters" Pete, v

entsrisi w r 1. An apparatus of -.the ;type describedpompris ne' an x er a ahe ted rou h-0 119110 8;very. 40

na r qp t n to en nd- ;depth. im-i bedded;in firegesisting material fixed in ametah -box eradle the cradle, having a; flat; slantin 1 pie e-=-top.-;pr0vided with an opening which TCQI;

r onds .and-1communicates-;with,; the;.erueilole;

rim the; cradle- .tiltablysuspended on :trun-nions; etwee s d rds b a i a inn tiha::t pv

mm? havin a. fiat under surface; slanting ,c o'-;-,

n id nt l as p .i he e d wh n-111 ri h ah hav n rancp n mm ni a neiexus l w th; 1;. h ent a h a e Q l h in and fi er; ppar t s com in di w e fra e: the .-poiht; A of l trunnions and hearings. thereof in hestahdarda and the s-sla ne an l of s d 100,-.- z.

b le and ny e toid su s 'id sur acese asse w -tos rmitirchareineehiss;

el'iarging and-recharging; of the crucible. withi ore; andmeansior heatingrsaid crueihle.

, #21 5111 apparatus 'oialzthe type described;':= elongated i: trough-eici'ucibl'e 1.substantially of. V shape in :crussv :SBCtiQn: and very narrow; in iproportion to lengthE-and' depthiigar ld ;meahs a"for; ;apz-x "plying heatexternally o;al1- sides:of.-;the,crucible; 7

xc t; the -t0p -f :di i11in 1 the .values; of; ore n ap a atus-0 hee d s ib slire e a ed .ireu hiic uci su st n al y bf 1 ape c'rossa e tionandv nar w, i .:pr r 9nto lengthand depth and having-asloping"butt m cptionauyi toaomror; both ends, descend nglinto;

ducts: 88:5 which .may12be.-'r.emOYed inf-10,5,

in this specification-aswellaS-flinthe ace; 7 any ne dr w ngs: shall-be, interpreted as.

channels and spouts at either end, the spouts having shutter stops to close the'drainage and to permit drainage of the crucible in upright position.

' 4. Anapparatus of the type" described com--- the flat surface of the frame coincides with the flat top of the cradle when in upright position, bringing the mouth of the crucible into registry with the entrance to the condensing system to complete an exclusive passageway for gases from crucible to condensing'system and being also such that the tilting of the' cradle will separate the flat surfaces and disunite' the from crucible to condensing system. 7 a

5. An apparatus of the type described comprising a crucible, means for heating same ex-- ternally, a condenser, means supporting said crucible for pivotal movement to permit said crucible to be swung downwardly for charging,

said crucible and saidcondenser having connections meeting at an angle whereby they may be separated and brought into registryfby movement of said crucible.

6. An apparatus of the type described, an elongated trough crucible substantially of V shape in cross section, very narrow in proportion to length and height with combustion means and rectangularly moulded helicalfcombustion cells surrounding same and all imbedded in fire-resisting materials fixed in a cradle characterized by a slanting plane top, said top having an opening equal to the crucible rim and communicating" therewith; means supporting said cradle for tilting movement but normally maintaining the cradle inoperative position; the cradle suspension being in combination'with a stationary fume condenser and filter system having an opening i leading thereto; said crucible being movable from chargeable position-to a normally operative'position withits outlet in registry with said opening. '7. An apparatus of the type described consisting] of an externally heated crucible very narrow in proportion to length and depth having an open top normally-lying in'a'n inclinedplane and provided with a closable drain spout at the bottom, said crucible imbedded in a'cradle of fire-resisting material with means supporting same for tilting'movement downwardly to charging positionyand afixed condensing and filter system having an'opening leading thereto, said crucible being movable into anormal operative position;

with its topint-registry with said opening, the crucible further characterized by sloping bottom, drain-oif'channels and closable drain-off spouts.

'8. An apparatus of thetype described, an ore vapor condensing-and filter system in combination with and for attachment to, the ore vapor exhaust passageway from an ore furnace; the system comprising a continuouspassageway for said vapors exclusively through adjacent, connected cells-separately described as follows; a

dome drum of adequate reservoir capacity for reception and immediate expansion of all 'said passageway va'pors, with entrance and interior designed with curvatures for agitating the vapor column and inducing temporary relaxation of flow therein andconstructed of material permitting slight cooling of contents byradiation to the atmosphere and with an easily removable cover, said cell collecting the quickly condensible values frombends, the case provided with means to circulate a cooling 'medium and to regulate the temperature therein, with a device for indicating temperatures therein, said cells collecting values selectivelyl according'to known volatility and condensation temperatures; further, a filter case; with longitudinal cells therein alternately connected at opposite ends and separated only partially by baiiles alternately extending from opposite ends in such manner as to cause ore vapors to pass alternately back and forth through the case, each such cell packed with dry,'looselybanked, strands of such materials as asbestos and wool, said packs removably installed, the case provided witheasily removable covers to give access therein for removing filters and values.

'9. An apparatus of the type described comprising a "crucible, means for heating same exteriorly in .combinationwith a condensing system composed of a dome drum, with a removable-cover for condensing and collecting the least volatile values from ore, and a varying temperature continuous passage return-tube condenser in a case adapted to contain a medium for cooling same, terminal portions. of said condenserextending exteriorly of said case, and'slip-on bends for connecting terminal portions for access to the interior and means for cooling said condenser to different degrees of temperature, .at different points wherebyrore values are condensed selectively according .to volatilitypoints:

10. An apparatus of the type described com prising a crucible and means for heating same. exteriorly in combination'with a condensing system consisting of a dome drum, a curving throat- Way lip in said drum for turningv the vapor flow to induce precipitation and to serve as azreceptacle to receive precipitated values; and a continuous passage condenser comprising parallel tubes passing through acoolingfiase, ends protruding from said case and joined in series by removable slip-on returned bends which are machined interiorly to fit over the tube ends, means for circulating a cooling medium in said case whereby the temperature of the tubes may be controlled-and.

means for temperature indication in the me-' dium; the reverse passageways being operative to break the column of vapor flow therethrough to induce disruption and uniform cooling.

11. In apparatus of the type described, an elongated trough crucible substantially of a V shape incross section andvery narrow in proportion to length and depth, means for heating same exteriorly,- a cradle mounted for tilting movement and containing said crucible in combination with an ore vapor condensing. and 'fil-' ter system, the crucible havingpa slanting-planed top sloping towards one side to facilitate gas-tight junction of said top'with the entrance to the condensing. and filter system and disjunction by tilting the cradle.

12. In apparatus of the type described, an elongated. trough crucible substantially; of 'V,

shape in cross section and very narro'w pro 1 portion to length and depth, and means for heating the same exteriorly in said cradle, in combination with an ore vapor condensing and "filter system, the crucible having a slantingplaned top sloping towardsone side, a flat member having a sealed connection with the top of the crucible throughout the entire periphery thereof and extending in all directions from the crucible rim substantially upon said slanting plane of said crucible top to said edge of the cradle top.

.13. In apparatus of the type described, a vapor trap and condensing means consisting of a cell contained in an elongated dome drum the upper surface of which is semi-circular in cross sec- 3 tion in connection'andcommunication with the ore vapor exhaust passageway from an ore furnace, an entrance thereinto under a curved demoval of values condensed therein; said cellof sufiicient dimensions to adequately receive and permit expansion of ore vapors from, the fur nace, said dimensions and reverse passagewaybeing operative to interrupt the column of said vapors and partially impound same for cooling.-

14. In apparatus of the type'described, a series of parallel ore vapor condensing tubes in connection and communication with the ore vapor exhaust passageway from an ore furnace, the

tubes extending through a liquid type cooling case with tube ends protruding therefrom and connected in series tocomplete the continuous passageway for ore vapors'therethrough, slip-on return bends connecting tube ends and removable to permit recovery of values which condense in thetubes; means for circulating a 'cooling medium throughsaid case and a temperature indicating device in said case to facilitate'temperature regulation and condensation of values from ore vap'ors'in the tubes. 7 r

15. In apparatus of the type described, an ore V vapor filter system comprising a filter case connected to and in communicationfwith the ore vapor exhaust passageway from an ore furnace,

the filter case containing. parallel cells formed between. alternate parallel baflles, and alternately connected atopposite walls of the case, the baflles alternately extending from opposite walls of the case in such amanner as to cause ore vapors to pass continuously through the filter case in reverse alternate passage through adjoining cells; each such cell being uniformly packed with dry, loosely-banked, 'strands of such materials as asbestos and wool; said packs removably installed and the case being provided with removablecovers to give access therein for removing filters and values. I s I I 16. An apparatus of the type described, a complete ore smelting and distilling furnace having a fluid-fuel combustion means, a box cradle tiltably suspended in balance on trunnions in such a manner thatithe furnace may be inverted forcharging and dumping without substantial interruption ofv the smelting and distilling operation;

said combustion means and furnace being wholly contained in said cradle, a crucible in said furnacehaving a sloping bottom for drainage and ore vapor condensing and filter system whose 30 recovery of value, a frame supporting a complete entrance forms a severable, airtight junction with the mouth of the crucible when the cradle isupright on its trunnions, said crucible being located. within said frame, the mouth of the crucible and the condenser entrance meeting at reciprocal planes with reference to trunnionbearings and being so machined that registered junction may ,be readily made and broken by tilting the cradle on its trunnions.

' ALMER A.-'ANDERSON.

Images