US2826898A - Apparatus for mine roof control - Google Patents

Description

March 18, 1958 J. F. JOY

vAPPARATUS FOR MINE ROOF CONTROL Original Filed Oct. 6, 1948 3 Sheets-Sheet 1 A Oliv 4 N MS March 18, 1958 J. F.JoY

APPARATUS FOR MINE ROOF CONTROL Original Filed Oct. e, 194s 3 Sheets-Sheet 2 65N@ .NN QS,

1522/622262# ToseJv I.' Joy any.

March 18, 1958 J. F. JoY 2,826,898

APPgRATUs FOR MINE: ROOF CONTROL l original Filed oct. e, 1948 5 sheets-sheet s 22 Eig 4- /49 22 may United States Patente@ 2,825,598.. APPARATUS @Fone MINE `Roon-coisifrnonfacturng Company, Ritfsburgh;,Pa.,a .corporation of PennsylvaniaY v Original application October 6, 19.485, SelalfNo. 53,lulll,

nowPatent;N.2,152,757, .datedzlulnf 19.156 Dl- This invention relates to apparatusgfor mine roof conf` trolj-and more particularly-to an improvedV hydraulicallyoperated Walkingnjack mechanism having"rollingontacte with the mine door and root for supportingjthe latter;

An object ofthe invention is'to-provide an improvedy roof support: for an underground mine; Anotherobjectis to provide'animprovedroof supporting structure'having means Vincorporated therein-for `facilitating litsmbeing;l progressively advanced, along with `the advance of amine facefwithoutl substantial release of the resistanceto roof subsidence and with suieient 'yield'l providedq for antw matically to -accornmodateat le astjniinor localsubsi-l denc:es. vk Still another object is to provide improvedme-l chanically actuatedstructures forpthe controllofmipe,

roofs whichr support 'the roofclose up to-theface along,

Yet another object is to provide aniniproyedroof"jaeley mechanismy having improved means for'a1teriug-its--1ine` of advance. Other objects and advantages of there-inven-A tion will hereinafter4 more fully appear.4

Thisv application is a divi sion of fmyjcopending application Serial No. 53,070, filed October 6, l948,"nowrn`1a tured into Patent No. 2;752,757, dated'July--3,".1956;`-

In the accompanying ydrawingsin whichY- forpurposes` of illustration there is shown anr embodiment which'lfthe invention may assume in practice: p

Fig.1 is a plan viewof ankillustrative embodimenteof the improved rootjacle structure.-

Fig. 2 is a side elevational view of the structure shown in Fig- 1.vv

Fig. `3 is `an enlarged vertical sectional view= taken-on the plane of line 3 3 ofvFig. 1.

Fig.-4 is a-somewhatdiagrammatic vview showingfthe ui'd pressure operating sources and connectionswffo'r effecting the roof supporting and 1walking;.operation :of the jacksf Fig. `5 is' air-agmentary sectional. iview: through; theibotf tom end of a pump used to supply-Huidto-thetrooffsupe porting jacks.

In4 the-illustrative `construction,-.as shownfin theqdrawfS ings; the improved walkingroofsupporting jacks comprise two upperandI ltwo =lower frames .havingroof andi lloor engaging-'devices on them.. one long upper: lframe :at each side, and onevlonglower -framerat each-sidei'and eachof the ljacl: deviceszl and 2 has-iupperfand lowery transversely extending frames 'rigidlyr connected atioppositeendscwith A ,furtherobject isuto provide anirnproved"y 2,826,898 ice Patented` Mer..,18,k 1953 elongated longitudinally extending;-` guide Yv frames 4:

Thjere are; thus twoy upper guide -franjies anda-two'. lower guide -framesthe frames -Vof -each-pair being-spaced Ibythe width of the cross frames \frorn-eachl-other.- The" guider-frames 4 may be of` any suitable @con-struction;- for example,t of frail-orgenerally 'I-beamconstruction-5^A being' herein- 4shown as-'formed by rigid yrailV #sections With-semifcireular guide elements 5 fattheiropposite ends,-theguide" elements 5-at-one end of:each-guideV frame-being `rela-1V tivelyJfadjustablelto insure suitable tension forY the roller connecting elements'shortly to besdescribed. l The lowery frames 4 have shallow Ichannel sections 6 suitablyvsecuredg as by welding :or otherwise, to 1 their# heads-and have their basel lflanges provided with :side ledges-T to provideJ forA the later-al i guiding Vof a` series -of {rollers-8 f-.which'iare adapted to provide a` rolling support-tor therlower frames- 4-as the -jacklinechanism is advanced..l Theinverted upper railr 'elements Aoifthe* upper rframes 4 l1fave-v sideledges -9 fat th'eiritopstov-guidethetfassociated rollersk 8,and to support the lower-run of.-'rollers'-associatedywith the upper-guide frame-=4;fthere isdisposed beneath-them and spaeedbe neath1gthe-bott-omofeach upper-guiderframe," an elond4 gatedliguide'astrip or-channel bar-;10 which; ishheld'fin -the desired spaced relation kto -themframe 4 whichfis above it;

byzspacing platessll'fsecuredv tol the-guide bars iandto the sides-oi--the frames `'-lsf The rollers Suarefprovidedwithfy through pinsl21`fand between thesezpins andthef-rolle'rsf thereare mountedsuitable bearings' (notshown): TheA oppositefends oit-itli'etpinsl are :suitably-bored,-i ,asvrshpowneine Fig 3,at13,tol permitl anendl'ess cabl'er141to1extend through/thev variousopenings-fandy provide'a connectionf between the rollers, and in'order-thatfth'e rollers Imay notcontact with eachottieni-these-pinsmayfbe'iiitcd-inspacedz apart-^relation tothe cable loop--as by axial clamping screws 15.

Thel devices or--extendingf-thejack elements-fthe deA vicesrfor-feeding them;etc.v--includes---the =front-andrearroofSi load-sustaining v-'jackl devices 11'andv=2, anfuprighg abutment jack device generally.l designated 16?i anY-ex-` tendible Awalking jack device generallyJ designated--17 for-A impartingh repositioning forces to the jack devices, will now "be described. f It: Vwill be v observed-that many of the parts ofthe frontandrear fja'ckdeviccsware Kidentical;v and, therefore ya-detailr description'fxof Jthefgjackidevice lwillfy suiii'cel forsboth jackdevice's. I The jack: device issh'own as -ofthe lhydraulic'pressure operated type-aand f-is carriedby a lowervetran-sversely Vextending'framelorcrossframe memberg '-and includes, asy -fully`vdisclosed inf the copend-v ing-application Y.Serial No.. 53,070,- now= Patent-No 2,75 2,757, a vertical cylinderY -19 in" -whichi` a hollow/pistoni element-2li -'is reciprocable.` The v reciproc-ableihol-low Lpiston has-an-upper-head 21havinga boss-ionprojectionfZZI looselyv received in an opening- 23 forrned'inatopewalllof` the upper 1transversely-extendingframe3; T he piston has rigidly secured thereto at its lower; end a suitably packed piston head-124; The piston head isi recessedlat ZSIat'its lower-,side and-a passage :2 61extends from thislrecess throughv the rupper surface of the piston l24, 'fand ya member 27threaded'within the pistoni-provides amounting fo`ra conventional. accumulator zfwhichimay be, for exampley of theiG're'eritypefv Liquid may owfrornthepassage 26 tothe interioriofthe lflexible' rubber` bag-foffthe?accumu-l latort A suit`able iillingconnection 291to1'.ithei-'accurnuf-E latoi-isnprovidedat the top of: the.faccumulatorll'whereby` the latterk -maymbefpreloaded with gaseous.A Huid' from` `an externalI supply..y The other roof-support 421isfoiz'fa vsimilari construction.- Liquid under 4pressurefmaybe supplied :to the hydraulic` jacks by a conventional-.handfoperatedipumpY mechanismwhich is connectedto. aliquid reservoir-orV tank 31u `The `entendible*,jack'dev-ice*.17 isinthe foljm-Of aait/allie. ingjaelemeehanisxn,including `21l1orizontal, longitudinally extending cylinder 33 containing a reciprocable piston 34 having its piston rod 35 connected at 36 with a boss 37 on a collarlike element 38 surrounding the cylinder of the abutment jack device 16. The cylinder head 39 is pivotally connected at 40 with a collar 41 surrounding the cylinder element 19 thereby to enable the cylinder element to swing vertically.

The abutment jack device 16 includes a vertical cylinder 43 closed at its bottom at 44 and having a mine floor engaging support element 45. Within the cylinder there is reciprocable a piston 46 having its upstanding tubular piston rod 47 carrying a roof engaging element 48 at its upper end. Liquid may be admitted to and vented lfrom the cylinder beneath the piston through a conduit 49.

Liquid may be supplied to the liquid supply conduit 49 through a passage 50 formed in the cylinder head 39 of the walking jack and leading to the bore of a conducting tube 51 mounted within the cylinder head 39 andv tele scoping with the hollow piston rod 3S which receives the tube. Liquid may be admitted to the opposite ends of the bore of the cylinder 33 through conduits 52 and 53 formed in the cylinder heads respectively. Each of the liquid supply connections 50, 52 and 53 will desirably be equipped with a fitting through which liquid can be supplied to it past a stop valve, as fully disclosed in my copending application above referred to.

In view ofthe tact that the abutment jack device 16 and the walking jack device 17 will have liquid supplied to them and vented from them only on the order of perhaps once or twice, or at most a very small number of times, a day, it is unnecessary to provide liquid reservoirs and pumps individual to them, and instead a portable liquid supply and discharge arrangement such as is shown in my Patent No. 1,900,446 may be provided to supply liquid under pressure to extend the abutment jack device 16 and to move the cylinder 33 relative to the abutment jack, or to allow the venting of liquid; it being understood with respect tothe walking jack device 17 that it will be necessary to provide a return connection from whichever one of the connections 52 or 53 is not to have liquid discharged to it from the apparatus shown in said Joy patent. Such a liquid supply means is portable from jack to jack.

It may be noted that the abutment jack device 16 may be repositioned laterally, as indicated in dotted lines in Fig. 1, so as to cause the jack devices to change their direction of travel, that is, to be moved slightly laterally in one direction or the other as they advance toward the face. l It will be understood that the loose mountings of the upper frames 4 on the jack devices 1 and 2 permit limited lateral and longitudinal tilting ot' the solid upper frame structure including two frames 3 and two frames 4.

In Fig. 4, there is shown for purposes of illustration, a control diagram. This diagram shows the connections so far mentioned, and also others. The roof jack devices are shown at 1 and 2, the abutment jack device at 16, and the jack device for effecting walking is shown at 17. The abutment jack and the walking devices are adapted to be supplied with liquid under pressure from a separate power driven pump device 55, such as is shown in my Patent No. 1,900,446.`- The only material difference between the device of the patent and the device shown at 55 resides in the fact that a return conduit or connection 56 is provided for the back ow of liquid from a working space which is to be vented to the reservoir of the device 55, and of course the reservoir size and the discharge pressure will be predetermined to the demands of the work to be done. If desired an adjustably loaded relief valve 57 may be arranged between the discharge conduit 58 from the device 55 and the return line to the reservoir. Each of the connections 50, 52 and 53 will be provided with a stop valve (shown in Fig. 4 at 59, 60 and 61), and suitable quick detachable connections, as of the Hansen coupling type, may be provided to facilitate connection and disconnection between the condiuts 56 and 58 and the connections 52 and 53.

The liquid supply to the roof jack devices 1 and 2 is, as has been previously noted, such that liquid under pressure may be supplied simultaneously to them, as will ordinarily be desirable, or separately, and liquid may also be vented simultaneously or separately from them. The manually operable pump mechanism 30 includes, as has been noted, a reservoir 31, a pump cylinder 62 and manual operating means 63 for the pump. An operator may therefore quickly pump up the desired pressures in the jack devices 1 and 2.

The supply of liquid under pressure to the cylinders 19of the jack devices 1 and 2 beneath the pistons 24 is by the hand operated pump mechanism 3), and a shelf 64 carried by the frame 3 supports the pump mechanism. This pump mechanism may be of any suitable construction and, as shown, includes the reservoir or liquid tank 31, and the `pump cylinder 62 in which a plunger 65 is adapted to be reciprocated by the operating means 63. The bottom of the pump cylinder communicates through a passage 66 (Fig. 5) with a chamber 67 which is arranged between a pair of check valves 68 and 69. The check valve 69 controls communication with the discharge line 70, which opens into a valve casing 71. The check valve 63 controls communication between the reservoir V31 and the chamber 67. The valve casing 71 contains a valve (not shown) shiftable to connect the line with a conduit 72, leading to the bore of the cylinder of the jack 1 beneath the piston, or to connect the line 70 with a conduit 73 leading` to the cylinder bore of the jack mechanism 2, or to connect the line 70 with both conduits at the same time. A return connection from the line 70 to the reservoir is provided at 74 and is controlled by a valve 75. The reservoir has a supply connection 76, and additional liquid will be supplied to the reservoir, as needed, while the jack devices are being extended to provide approximately the desired elevation of their upper portions. Means for releasing pressure from the bores of the cylinders beneath the pistons in the event of excessive roof pressures is provide-d in the form of two relief valve control means 77 and 78, these having the relief valves therein set at pressures higher than any normally desired pressure in the cylinder bores beneath the pistons but adapted to permit the return of liquid from these bores through a common conduit79 to the line 74 as pressures such as to endanger the accumulators 28 are occasioned by markedly increased 4roof pressure.

The upper andlower roller carrying frames 4 associated with the roof supporting jacks 1 and 2 arc connected together by the cross frames 3 and extensible parts of the roof supporting jacks and clue to the multiplicity of rollers and the substantial length of the up- `per and lower beamlike frames the pressure per square inch of contact with the floor and roof is substantially reduced, and yet these roller frames are capable of rolling along the oor and roof without excessive forces being required. Thus the roof supporting jack devices 1 and 2 are connected together by the upper and lower' frames and the cross frames so that forward movement of one jack device will be attended by corresponding movement of the other jack device and yet, if there is uneven subsidence of the roof, there may be limited tilting of the upper frames relative to the jack devices. Change in the direction of jack travel may also be facilitated, as` mentioned above.

When the roof supporting apparatus is in roof supporting position, as shown in Fig. 2, the roof supporting jack devices 1 and 2 will be subjected to hydraulic pressure from the pump mechanism 30 in such manner that they will provide the desired roof support, and the forces will be applied to the roof through the series of roof contacting rollers 8, resulting in a substantial area of contact between the upper roof supports and the roof forced. .intostheaccumulator, lincreasing the.- pressurent theconlnedgaseous iluidin-` the vacc un1ulator bag. and therebylin many cases enabling; continued nonerigid withstanding of increased roof'v pressurer, Whenrtlre, roofA jacl; underlyingthegarea; of increased;pressuresis ad; vanced from beneath .I thatz areaathefgaseous uid :under increased pressure in thenaccumulaton'bag will displace liquid from the f accumulator and cause, the return. of the roofv engaging portions 0f the jaekgzdevice tto its previo/us.v lev e l. Of cou1 se,4 as. -has been; ;previously explained; before the pressurecould ghe/ built up in. thetaccumulators sufiicient to rupture .thebags therein,thetreliefnvalve means heretofore describedinthe connections?? iand/ on 78 would allow the,escapeiof1fluid and.thesubstitutionj of asolid yfora yielding support fori the .roofA pressures The provision of the .yielding support of course,.facili-t tates the advance ofthe jacks overuneven bottornruor. beneathuneven roof.\ Further explanationcitheimodef of operation and advantagesof theinventionisclearly unnecessary, since the manner of, extendingthe jack def viceofthe roof-supporting jackimechanisms,thernanner` o f extending and -collapsing they abutment, v jack device 16 andthemanner of ,supplying ,the lluid to the oppositel en dsoflthe walkingjack devicellfwillV be clearlyxap.- parentfrom vthe description already givem A sfa ,result of this invention an improvedpmine .roof supporting apparatus is provided having animproved arrangement ofthe `oor engaging and roofv supporting roller-carrying supports. By the .provision.r,of thelrigid, longitudinally extendingl elongated beam Amembers .for carrying the rollers, and 'the associated supporting parts, theirnine Aroof is at all times adequately ysupported while the apparatus without release ther eof may bei readily; advanced as the .minevfaceadvances The prQi/iSionofl theabutment jack, together withthehorizontally swingable walking jackconnected thereto, enable the roof` supporting apparatus to be advanced in variousdirec.. tions as determined by thelateral positionofthe ahnte mentv jac l Thetstructure is relatively simple andrugged iiidesign, and extremely cornpact,l well adapted fortits,x intendempurpose, Otheradvantages Y-of'- the invention WilL-,b clearly )apparentto those skilled, in the art.-

While there is; in; this application,v specicallydescribed-4 onet fo r m which L,the f invention may assumein practice, it; will .bei understood :that` thiszformof thesame. ist shown for purposes of, illustration and that the; invention may be. rnodie d anden1hoded -in i various, other. forms ,withf` out departing from its;r spirit or the. scopeof the; appended. ClELlLIl'lS-pl Y i Whatl claimfrasnewzand, desire to secureby Letters; Patentris:

1a Ina mine rooiisupprorfting jack mechanisrma ,pain @f elongated, substantially vcoextensiveand superimposed roof and floor engaging ;devices,v eachilofusaid., devices iacludinafan eiengated framesand rolling Contact means giiidedfer.freereibitaleireulatienthereabeiit, eaehttrame, having guiding means for said rollingcontact ymeans :in-T e1nding; upper;;. andt tlower, guideways, extensible .ieek' means arranged between vsaidi frames V:for elevating said; roof engagincedevice relative to said,oorlengagitisde: vieltqbrjng said {roof- ,engaging devicerrmlyin .supf portingfengagementgwithgthe mine,roof,.and -a powen operated Adevice ort-feedingesaid rst mentioned devices horizontally insunisonifwhileasaid first. mentioned devices aresmaintainedfinsupportingxrelaton Withffthe roofeand; oo1,;,and tsaidfrollrig contactameanssgcirculatins freelyt f6 l eleaaasaida gaidiiiaameaiistrelativeate. fSaidefr-anies-durias; suenh ali- Vaiiedi witiifrespeet tQ-the-.lengitudiiial exis the,"I Jaels.

mechanismito -varyfi-thedirectiqn of 4travel v `ol`, said i roofiand. Hoor.. engaging devices.4

3 Arieek1meei1eiiism 21S-Set ferthrineelaim '1 fwhereiiit said power operatedieedingdevicej has anchor-:mesmel providing retienen/peint ltherefor during thev feedingA Operatieii.;y

4. Afjaclcme`hanism-- as .set forth ingclaimf wherein.- Said `rptiwerfoperated:-devieeehes .means Viet Shifting the.' angular.. positiontlrereof; horizontally to-,YarY-.the dire: ,v tion of feedf v 5f 111,: amineareeffsiippetting jack mechanism a pair offelongatedx substantially coextensiveand superimposed roof,-and, oogengaging Idevices, each ofsaid devicesl including an eleiigetedxframe and rolling eontaetmeans guided forfreeforbitalt circulation thereabout, each iframe having uidingl means for rsaid rolling contact means ill-E cludingiupper andflowerguideways, extensible jack means` arranged betweenipsaid frames for elevating said roof engagingdevise.frekitive-te Said iieorv engaging device tot brins aseiids.teef.v engaginaffdeviee firmly in Suptwrtiiigv engagement with the mine,roof-, said extensiblejaclr means inc lodingfjack, devices arrangedbetween and u longitudinally of i said-frames and acting on said framesI at points -located inwardly of the ends of saiucl r s t-n1entione d devices with saidiirst mentioned devicesy c .rrwerdlrand rearwardly/with. Arespeet. tesaidv javi? devieesto provide .Substantial overheen. andra pov/er1 Operated f. deyieetferrfeeding Said frstgmentioned de-r vices@ horizontally in` f unison while said t rstrmentioned devintrsj aremaintained.insupporting relation with` the roof andi,oor and said rolling abutment ymeans circulan ing :freely alongsaid guiding` means relative tolsaidframes during suc h :horizontalmovement. f

6,In-a mine yroof supportingrjack;fmechanism, apain 0f zeerigatedt; Substantially eoeXteiisivev and-.superimposed roofpgand door fengaging ,I devices each of said devices including an elongated frame and rollingcontact means, guided for free circulation thereahoutfextensiblejack means arranged between .said1 frames l for elevatingsaid roof, engaging device relative to saidgoor engaging device t0, bringsid reef engaging device firmly iii-,supporting en: sagement .with the mine Yreoffsaid extensible jack means including jack devices arranged between andspaedlongi; tudinallyof said frames andacting on saidf-r-ames at points located inwardly of the ends of saidrstmentioned devices with.-saidiirst mentioneddeviees projecting forwardly .and rearwardly with respect to v4said ;jac k devieeS; t0 ,prov id e, substantial overhang, -and a power` operated -devicef;forfeedingsaid first mentioned devices,horizontallyginzuni-A son while said first mentioned dev ices. aregmaintained; in supporting relation withthe roof and floo'nfand, said rollingicontact means circulating` freely` relative to v-saiid framesduring such horizontal movementyandfsaid power operatedldevicearranged longitudinally of saidv first mena tioned devices between said longitudinally spaced jack devices `andoperatively connectedto oneof the latterv 7.fln a vmine roof supporting jack mechanism,v a pain of elongated, substantially coextensive andsuperimposedroofv and .floort engaging devices, each'of said rdevicesincluding an elongated frame androlling contactv means guided 4for free circulation thereaboutf said rolling con.l tact means eachy having. guideways therefor extendingaboutzthe frame-margin. and including atseriesiof rollers rotatable .about axes transverse 4to the rameand means, for lconnecting said rollers for movement in an `orbital path ahonty said. 1 guideways: extensiblegiack means...1 arf. ranged between said frames for elevatingsaid; groofrena seeing; derieerrelativeftdsaidaileer.engagingrdevieerto bring said roof engaging device vfirmly in supporting engagement with the mine roof, and a power operated device for feeding said first mentioned devices horizontally in unison while said first mentioned devices are maintained in supporting relation with the` roof and floor, and said rolling contact means circulating freely relative to said frames during such horizontal movement.

8. In a mine roof supporting jack mechanism, a pair of elongated, substantially coextensive and superimposed roof and floor engaging devices,feach of said devices including an elongated frame and rolling contact means guided for free circulation thereabout, extensible jack means arranged between said frames for elevating said roof engaging device relative to said fioor engaging device to bring said roof engaging device firmly in supporting engagement with the mine roof, said rolling contact means each having a guideway therefor extending about a frame-margin and including a series of rollers rotatable about axes transverse to the frame, shafts on which said rollers are journaled and flexible means for connecting said shafts for movement in an orbital path about said guideway, and a power operated device for feeding said first mentioned devices horizontally in unison while said first mentioned devices are maintained in supporting relation with the roof and floor, and said rolling contact means circulating freely relative to said frames during such horizontal movement.

9. In a mine roof supporting jack mechanism, a pair of elongated, substantially coextensive and superimposed roof and floor engaging devices, each of said devices including an elongated frame and rolling contact means guided for free circulation thereabout, extensible jack means arranged between said frames for elevating said roof engaging device relative to said floor engaging device to bring said roof engaging device firmly in supporting engagement with the mine roof, said rolling contact means each having a guideway therefor extending about a frame-margin and including a series of rollers rotatable about axes transverse to the frame, shafts on which said rollers are journaled and flexible means for connecting said shafts for movement in an orbital path along said guideway, said flexible means comprising an endless cable and means being provided for attaching said shafts at intervals to said cable, and a power operated device for feeding said first mentioned devices horizontally in unison while said first mentioned devices are maintained in supporting relation with the roof and floor, and said rolling contact means circulating freely relative to said frames during such horizontal movement.

l0. In a mine roof supporting jack mechanism, a pair of elongated, substantially coextensive and superimposed roof and floor engaging devices, each of said devices including an elongated frame and rolling contact means guided for free circulation thereabout, extensible jack means arranged between said frames for elevating said roof engaging device relative to said floor engaging device to bring said roof engaging device firmly in supporting engagement with the mine roof, said rolling contact means each having a guideway therefor extending about a frame-margin and including a series of rollers rotatable about axes transverse to the frame, shafts on which said rollers are journaled and flexible means for connecting said shafts for movement in an orbital path along said guideway, said flexible means including parallel laterally spaced endless cables arranged at the sides of the frame and there being means for attaching said shafts at their ends to said cables at intervals along their lengths, and a power operated device for feeding said first mentioned devices horizontally in unison while said first mentioned devices are maintained in supporting relation with the roof and floor, and said rolling contact means circulating freely relative to said frames during such horizontal movement.

1l.` In a mine roof supporting jack mechanism, a floor engaging device comprising elongated parallel side frames and means for connecting said side frames in rigid transverse relation, a roof engaging device com-V prising elongated, upper, parallel side frames and means for connecting said side frames in rigid transverse relation, said upper side frames being arranged in parallel, superimposed, and substantially coextensive relation with said lower side frames, rolling contact means guided for free circulation about each of said frames, and jack mechanisms spaced apart longitudinally of said frames and arranged between said upper and lower connecting means and engaging the same intermediate said side frames for elevating said roof engaging device relative to said floor engaging device to bring said roof engaging device in firm supporting relation with the roof.

l2. ln a mine roof supporting jack mechanism, a floor engaging device comprising elongated parallel side frames and means for connecting said side frames in rigid transverse relation, a roof engaging device comprising upper, elongated, parallel side frames and means for connecting said side frames in rigid transverse relation, said upper side frames being arranged in parallel, superimposed, and substantially coextensive relation with said lower side frames, rolling contact means guided for free circulation about each of said frames, jack mechanism arranged between said upper and lower connecting means and engaging the same intermediate said side frames for elevating said roof engaging device relative to said oor engaging device to bring said roof engaging device in firm supporting relation with the roof, and power operated means for moving said devices horizontally in unison while said devices are maintained in supporting relation with the roof and floor, and said rolling abutment means circulating freely relative to said frames during such horizontal movement.

13. ln a mine roof supporting jack mechanism, a licor engaging device comprising elongated parallel side frames and means for connecting said side frames in rigid transverse relation, a roof engaging device comprising upper, elongated, parallel side frames and means for connecting said side frames in rigid transverse relation, said upper side frames being arranged in parallel, superimposed, and substantially coextensive relation with said lower side frames, rolling contact means guided for free circulation about each of said frames, jack mechanism arranged between said upper and lower connecting means and engaging the same intermediate said side frames for elevating said roof engaging device relative to said floor engaging device to bring said roof engaging device in firm supporting relation with the roof, and power operated means for moving said devices horizontally in unison while said devices are maintained in supporting relation with the roof and floor and said rolling contact means circulating freely relative to said frames during such horizontal movement, said transverse connecting means connected to said side frames at longitudinally spaced points and said jack mechanism including a pair of jack devices connected between said transverse connecting means at each end of said first mentioned devices, and said first mentioned devices extending forwardly and rearwardly a substantial distance with respect to said jack devices to provide substantial overhang.

14. In a mine roof supporting jack mechanism, a floor engaging device comprising elongated parallel side frames and means for connecting said side frames in rigid transverse relation, a roof engaging device comprising upper, elongated, parallel side frames and means for connecting said side frames in rigid transverse relation, said upper side frames being arranged in parallel, superimposed, and substantially coextensive relation with said lower side frames, rolling contact means guided for free circulation about each of said frames, jack mechanism arranged between said upper and lower connecting means and engaging the latter intermediate said side frames for elevating said roof engaging device relative to said oor engaging device to bring said roof engaging device in firm supporting relation with the roof, and power operated means for moving said rst mentioned devices horizontally in unison while said first mentioned devices are maintained in supporting relation with the roof and oor, and said rolling contact means circulating freely relative to said frames during such horizontal movement, said transverse connecting means connected to said side frames at longitudinally spaced points and said jack mechanism including a pair of jack devices connected between said transverse connecting means at each end of said devices and said rst mentioned devices extending forwardly and rearwardly a substantial distance with respect to said jack devices to provide substantial overhang, and said power operated means including a horizontal jack device arranged longitudinally of said rst mentioned devices intermediate said jack devices and operatively connected to one of the latter. v

15. In a mine roof supporting jack mechanism, a pair of elongated, substantially coextensive and superimposed roof and floor engaging devices, each of said devices including an elongated frame and rolling contact means guided for free circulation thereabout, extensible jack means arranged between said frames for elevating said roof engaging device relative to said door engaging device to bring said roof engaging device firmly in supporting engagement with the mine roof, and extensible jack means having anchor means and operatively connected to one of said rst mentioned jack means for feeding said roof and door engaging devices horizontally in unil0 son while said devices are maintained in supporting relation with the roof and floor, and said rolling contact means circulating freely relative to said frames during such horizontal movement.

16. In a mine roof supporting jack mechanism, a pair of elongated, substantially coextensive and superimposed roof and oor engaging devices, each of said devices including an elongated frame and rolling contact means guided for free circulation thereabout, extensible jack means arranged between said frames for elevating said roof engaging device relative to said floor engaging device to bring said roof engaging device rrnly in supporting engagement with the mine roof, said extensible jack means including jack devices arranged between and spaced longitudinally of said frames and acting on said frames at points located inwardly of the ends of said first mentioned devices with said rst mentioned devices projecting forwardly and rearwardly with respect to said jack devices to provide substantial overhang, and extensible jack means having anchor means and operatively connected to one of said first mentioned jack means for feeding said rst mentioned devices horizontally in unison while `said first mentioned devices are maintained in supporting relation with the roof and oor, and said rolling abutment means circulating freely relative to said frames during such horizontal movement.

References Cited in the le of this patent UNITED STATES PATENTS 1,588,987 OToole June 15, 1926

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