US2062660A - Mining machine - Google Patents

Description

M. P. HOLMES MINING MACHINE Dec. 1, 1936.

Filed Jan. 19, 1934 5 Sheets-Sheet l 5T +T mm W N H \l\.ll M 51 5%? @w gww u 7mg fi q 2 i: w 52:1 42 m. Wm v Q Maw" H @H H EV I I I I Q L Q Dec. 1, 1936.

M. P. HOLMES 2,062,660

MINING MACHINE Filed Jan. 19, 1934 5 Sheets-Sheet 2 H HER I :2: I I 4 2 I 5 A /;///J: /////2 z- IEIIIIIIiQ lieuenjbm- Dec. 1, 1936. M, p HOLMES 2,062,660

vM. P. HOLMES MINING MACHINE Dec. 1, 1936.

Filed Jan. 19, 1934 5 Sheets-Sheet 4 1 7 a 1 j 6 @P A d W PM y 00 H lit|i| I M J m MTG HM W 1 a 1 m 00 M H u M o/mllw 9 W "4 W 6. .W mm w W %W Patented Dec. 1, 1936 UNITED STATES NIINING MACHINE Morris P. Holmes, Claremont, N. 'H.,wassignor to Y Sullivan Machinery Company, a; corporation of Massachusetts Application January 19, 1934, Serial No.;'7 07,321

19 Claims.

This invention relates to mining machines, and more particularly, but not exclusively,'to improvements in coal mining machines of the flexibly fed,ifioor cutter type.

An object of this invention is to provide an improved coal mining machine. Another object is to provide an improved mining machine having improved adjustable kerf cutting mechanism. Another object is to provide an improved adjustable kerf cutting mechanism for a coal mining machine of the flexiblyfed, floor cutter type. A still'further object is to provide an improved mechanism for adjusting the kerf cutter of such a machine. These and other objects will, however, hereinafter more fully appear.

In the accompanying drawings there is shown for purposes of illustration one form which the invention may assume in practice.

In these drawings,-

Fig.1 is a planview of the illustrative form of theimproved coal mining machine.

Fig. 2 is a side elevational view of the machine shown in Fig. 1.

Fig. 3 is a longitudinally extending vertical sectional view taken substantially on line 3-3 of Figs. 1 and 4.

Fig. 4 is a horizontal sectional View taken substantially on line 4-4 of Figs. 2 and 3.

Fig. 5 is a cross sectional view taken substantially on line 5-5 of Fig. 4.

Fig."6 isa detail View showing structural details of the improved cutter adjusting mechanism.

Fig. 7 is a longitudinally extending vertical sectional view taken substantially on line 'i'! of Fig. 1..

Fig. 8 is a cross sectional view taken on line 88 of Figs. 2 and '7.

Fig. 9 is a horizontal sectional View takensubstantially on line 9-9 of Figs. 2 and 7,.

Fig. 10 is a detail sectional view taken on line IB+IB of Fig. 9.

In this illustrative embodiment of the invention there is shown a coal mining machine of the flexibly fed, floor cutter type generally comprising a portable base, herein preferably in the form of a bottom skid I having a plane bottom surface 2 whereby the machine may rest upon and slide in any direction over the mine floor. Pivotally mounted at 3 on a transverse axis at the rear end of the skid for swinging movement in a vertical direction relative thereto is an elongated arm structure 4 overlying the skid and having adjustably mounted thereon the improved adjustable. kerf cutting mechanism generally designated Thekerfcutting mechanism includes a r tatable cutter head'G mounted for rotative movement relative tothe arm structure about an axis extending longitudinally of the arm structure, and-having pivotally mounted thereon for swinging movement relative thereto about a transverse axis at La cutter support 8 whichcarriesan endless chainkerf cutter 9. The machine is-fed over the'mine'floor by improved flexible feeding means including relatively rotatable feed operating and controlling cable winding drums l0 and H cooperating respectively with flexible feeding and controlling cables l2 and I3. Arranged on the skid beneath the arm structured 'andin advance of the drums are inclined; guide sheaves l 4, l4,;while arranged at the opposite front corners of the skid are horizontalguide sheaves l5, l5. These guide sheaves guide the feeding andcontrolling cables in various directions during operation of the machine, in the manner well understoodby-those skilled in the art. The machine may be fed Iongitudinally and laterally over the mine floor to 20 effect sumping and withdrawal cuts and connecting transverse or rectilinear-cuts, andthearm structure 4 maybe swung vertically relative to the skid to move. the cutter head'into different elevated positions wherebythe kerf cutter may cut 25 kerfs in any desired horizontal plan'esbetween the mine roof and, mine 'floor,"and the cutter head may be'rotated-jrelativeto the-arm structure to enable cutting of kerfs in vertical planes in the coal face, as will presently 'be described.

In this illustrativeconstruction, the arm strucmm 4 carriesamotor, hereinpreferably'of the reversible electric type having ,its power shaft H extending longitudinally of the arm structure, and in.this instance the casing, l8 ofthis motor constitutes a part of the arm structure and forms a connecting elementbetween av front head frame 19 rigidly fixed to the front end of the motor. casing and a rear frame member 20 rigidly fixed to the rear'end of the motor casing, the frame section 20. forming the housingfor certain of the transmission gearings," as presently described. The elements l8, l9'and ZOithusconstitute a rigid arm swingable in a vertical direction. about the horizontal transversely extending axis. 3 relative to the bottom skid ,l; The skid 'I is. provided with. upstanding side frames 2|, 2|, these side frames extending verticallyfrom the lateral edges of the skid bottom and having lateral 50 openings 22 through which the. cables l2, I3 may be extended laterally from the rear guide sheaves M. These side frames also have rearwardly located integral bearing supporting portions 23, as

shown in Fig. 2 having detaghable caps 24, and 55 receiving bearing sleeves 25 within which are journaled trunnions 26, 26 detachably secured, as by screws, to the vertical sides of the rear frame section 28 of the arm structure 4. It will thus be seen that the arm structure 4 is mounted to swing in a vertical direction relative to the skid about the axes of the trunnions 28, 26 journaled within the bearing supports 23 of the skid frame. The improved means for swinging the arm structure is arranged beneath the arm structure between the latter and the skid bottom and is operated by the motor power shaft IT, as hereinafter described.

The feeding and controlling drums l and II are, in this instance, arranged with their axes coincident with the axis of swinging movement of the arm 4, and the mechanism for driving these drums comprises a bevel pinion 21 keyed to the rear end of the motor power shaft I! and meshing with a bevel gear 28 journaled for rotation about the axis of a vertical shaft 29, in turn suitably journaled within the rear frame section 28 of the arm. Formed on the depending hub portion of the bevel gear 28 is a spur pinion 38 meshing, as shown in Fig. 8, with a spur gear 3! fixed to a vertical shaft 32 likewise suitably journaled within the rear frame 29. Fixed to the upper end of the shaft 32 is a spur pinion 33 meshing with a spur gear 34 herein arranged coaxially with the bevel gear 28 and likewise journaled for rotation on the vertical shaft 29. The bevel gear 28 and spur gear 34, respectively, constitute high and low speed driving elements and are connectible in driving relation with the vertical shaft 29 by means of multiple disc clutches 35 and 35, respectively. These disc clutches are provided with improved operating means to be later described whereby the shaft 26 may be driven from the bevel gear 28 at a relatively high speed or from the spur gear 34 at relatively low variable speeds from zero to a predetermined maximum low speed. Formed on the lower end of the vertical shaft 29 is a bevel pinion 31 meshing with a bevel gear 38 having its hub fixed to a horizontal shaft 39, herein extending longitudinally of the arm structure and suitably journaled within the rear frame 26. Fixed to this shaft 39 is a worm 46 meshing with a worm wheel 4| keyed, as shown in Fig. 9, to a horizontal transversely extending drum driving shaft 42, herein arranged with its axis alined with the axes of the drums l0 and H and the arm pivot axis. This shaft 42 is suitably journaled within the rear frame 28 and in turn has journaled thereon and supports the drums l9 and H. The drums I0 and H are connectible in driving relation with the shaft 42 by multiple disc clutches 43 and 44 respectively, housed within the drums and having operating means including a control rod 45 extending axially through a central bore 46 in the shaft 42 and having fixed thereto at its opposite ends operating handles 41 and 48, these handles being arranged at the opposite side of the machine within chambers or recesses 49 formed within the trunnions 26, 26 of the arm structure. Each of these handles is provided with a hub 50 projecting within a bore formed in the shaft 42 and this hub is provided with clutch teeth 52 connectible with clutch teeth 53 formed on a clutch operating member 54 threaded at 55 within the shaft bore. The inner end of the member 54 engages lever elements 56 interposed between sets of clutch discs and acting on a pressure plate 51 for each set, these levers projecting inwardly through slotted apertures 58 formed in the shaft 42 in the manner shown in Fig. 9. it will thus be seen that when the handle 41 is slid inwardly from the position shown in Fig. 9, it is clutched to the operating element 54, and upon rotation of the handle the element 54 is rotated, and due to its threaded connection with the shaft, is moved axially inwardly, thereby swinging the levers 56 to effect spreading of the pressure plates 51 to apply the clutch, and as a result the drum I6 is connected in driving relation with the shaft 42. When the control rod 45 is slid in the opposite direction with respect to the shaft 42, the handle 41 is disconnected from its operating element 54, and upon rotation of the handle 48 the clutch within the drum H is applied, connecting the drum H in driving relation with the shaft. It will thus be seen that the drums in and II may be separately or simultaneously connected in driving relation with the drum drive shaft 42.

Now referring to the improved operating mechanism for the high and low speed disc clutches 35, 38, and more particularly to the improved operating means for the low speed clutch 38 whereby a variable low speed drive is attained, it will be noted that, as shown in Figs. 7 and 9, a cam or eccentric 69 is formed on the hub of the low speed gear 34, and engaging the surface of this eccentric is a lever 5| pivoted at 62 on an adjustable control member, herein an eye-bolt member 63. This eye-bolt member is threadedly connected within the hub of a control handle 64, the hub of this handle in turn being threadedly secured within the vertical end wall of the rear frame 20 of the arm, as shown in Fig. 9. This lever BI is provided with a projection 65 engageable with the inner surface of the vertical end wall of the frame 29 for limiting swinging movement of the lever Si in a direction outwardly from the eccentric. The opposite end of the lever 8| projects between the furcations of the bifurcated end 66 of a bell crank lever 51 pivotally mounted at 68 within the rear frame 20. The other arm of this bell crank is pivotally connected at 69 to a member 18 which, as shown in Fig. 8, has threadedly connected thereto at H and held in adjusted position therein'by a lock nut 12, a rod 13. This rod has a reduced portion forming a shoulder 14, and a spring 15 is compressed between a nut 16 threaded on the reduced end of the rod 73 and a collar 11 slidably mounted on the rod and normally engaging the shoulder 14 of the rod enlargement. The enlarged portion of the rod 13 passes through a trunnion device 18 comprising, as shown in Fig. 9, trunnion elements 19, 19 having concave recesses slidably engaging the cylindrical body of the rod enlargement, and these elements 19 are pivotally connected at 80 to a clutch shipper lever 8|. As shown in Fig. 8, this clutch shipper lever is pivoted at 82 within suitable bearing supports within the frame 20 and is provided with a yoke portion 83 engaging the shipper member 84 for the clutches 35, 36. This shipper member 84 is slidably mounted on a sleeve 85 keyed to the shaft 29 and is provided with clutch applying elements 86 for the clutches 35 and 36. This clutch shipper member 84 is operative to transmit the pressure of the clutch shipper lever 8| to effect loading of the disc clutches 35 and 36. It will thus be seen that when the parts are in the position shown in Figs. 8 and 9 and the eccentric 60 is rotated, the lever B! is swung about its pivot 62, thereby swinging the bell crank 6'! and moving the rod 13 axially in a downward direction. Movement of this rod in a downward direction will result in the transmission of no pressure .to. the 'clutchishipper. :lever B! untillthe sliding icollar Tl engageszithe upper. end of the trunnion-device 18', but that further movement downwardly .of the. rod will. thereafterdmpart "a loadto the clutch. shipper. lever 81: which will be determined by the extent. of the movement of the rod: and the degree of compression of the spring 15:. It is-therefore. evident that as the eccentric 60 revolves,.the shipper leverfll .is swung. back and forth intermittently'to apply-the disc clutch 3B; and. as a result, the shaft 29 is intermittently rotated at .a -relatively low speed. The. eye-bolt 63 provides a. movable fulcrum for thelever 6|, and. upon movement of this eye-bolt by the handle-.-64 in an axial direction, the interval of engagement of the lever-:61 with. the eccentric surface will be varied, and as a result, the time ofzapplicationzof the disc-clutch 35 will be correspondingly varied. Upon movement of the lever fulcrum. 62 to the right to a position sufficient to bring the lever B I out of engagement with the cam surface, the disc clutch 36 will'be maintained in released position during rotation of the cam. Upon-further movement of the eye-bolt to the right thenut 12 engages the bottom of thetrunnion device. 18 and swings the shipper lever 8| to move the shipper member 84 downwardly, thereby to apply the high speed disc clutch 35, the low speed disc clutch-being of course at that time released. When the eye-bolt is moved to theleft so far that the lever 6i continuously presses, under the pressure of the spring 15, against the trunnion device 18, continuous rotation ofthe shaft 29 will take place, and thespring will compress during eachrevolution of the cam an amount substantially equal to the full throw ofthe cam; but since the load of the spring is above the minimum necessary to efiectpower transmission through the clutch discs, there will be no release even when the lowest point in the cam is'opposite the point of engagement of the-lever 6| with the-cam. By moving the eye bolt graduatedamounts toward the right in Fig. 9, the period'of drive during each revolution of the cam'may be progressively reduced until it is entirely discontinued: Therefore, the drive through the low speed clutch 36 may be so adjusted as to obtain -a continuous maximum low speed drive and-an intermittent variable low speed drive from said maximum low speed down to zero, and a predetermined high speed drive may be obtained through the clutch 35; As a result, the feeding andcontrolling'drums' I 0 and II 'may be driven in'the cable winding direction at a relatively high predetermined speed, at a continuous maximum low speed and at intermittent low speeds between said-maximum low speed and zero. v The improved means operated by the motor for swinging-the arm 4 about its pivot relative to the skid comprises a screw shaft 88 suitably journaled on the bottom of the arm and disposed beneath the arm between the latter andthe skid, and in the present instance this screw shaft is arranged with its axis extending longitudinally of the arm and alined withthe feed drive shaft 39, as shown.

in Fig. 7. The bevel gear 38 surrounds the screw shaft 88, and arranged coaxially with this bevel gear and also driven by the bevel pinion 3.1- is a bevel gear 89, the bevel gears 88 and 89 rotating in opposite directions and constituting reversing gearszfor the screw shaft. These-bevel gears are.

selectively connectible in driving relation with the rscrew-shaft-BB-by multiple disc clutches; 9.0

andeilt respectively,- operated by, a ball bearing c1utch:shipper::member- 92? surroundinQzE-ndslid: ably .mounted :on: thewrearwa'rd .portion-. of the screw-shaft: 8& andzhaving a:-shipper yoke &3-..:. As shown inl;Fig.s 8., this: :shipper yoked-is: zpivotal'ly mounted-enra shaft 94 carried within .theiifra-me 2-D, and:has. an upstanding. lever bifurcated: at 9.5 forengagement withran eccentric zpin 9fi carried at the inner 'endrof 'fa'icontrol' rod 9l-rotatab1y mounted.withinxtheaframe zurand-ahaving anop erating leven:98'.a- Itwwi-ll? thus be seen that one or: the other of'thebevelgears- 38,,"39 maybe con,- nected tothe-screw: shaft'fifl to :eifect rotation oi the: latter? in either. ofopposite "directions. Threadedly'engaging this screwshaft 88 is ra nut 99 guided for rectilinear: movement within:a..lon-gi-.- tudinal' guidewaytt- [0.8.1: formed within as guide bracket I.B:l: :attached zto rth-ebottom: of. the ;arm structure-.2 'I'liliS1l11t'. has "oppositely. iprojecting trunnions. l Uzi/to. which there are 'pivotall-y, con nected the upper'ends. of links-v I=8'3*, these-l inks.-.in

turn being pivotallyconnectedrat .their. lower ends at 104 to-the.bottomofwtheskidr; It isac' cordingly evident that: 'as the screw: shaft.- 8.8;:isrotated in one direction the nut. 99.-is.moved:axial:- 1y within its guideway' [00,:sW-inging the.slinks;.-l03 about their pivot 1M, and asea result movingizthe arm structure 4 upwardly frornthefull line post tion shown in -Fig. 6 tothe dotted'line po'sition in that figure. When thesc'rew shaft. isnrotate'd in the opposite direction; the-parts: areof.=.,course swung in the:oppositedirection; r

Now referring to' the improved:kerficutting mechanism, it will be notedthat rotatablymounte ed on the head frame l9 of the armstructimeqdsis" a bifurcated or yokeshaped'iframe, lllifof the rotatable cutter head- 6 This head-1 frame will; is formed 'with a circular bearingirsupportr. I86 on, which the hub of a worm wheel 10'! is 'journaled; and the hub yoke I05 is fi-xed to th'e worm wheel as by-screws'l08. The yoke fr'ameeandahead frame cooperate to forma chamber:l-ll9riwithin. which the worm wheel l-ll'fi is 'housedg ands also: arranged within this chamber on a transverse axis is a worm H0 meshing-with the Worm wheel I01 and fixed to a transverse shaft'iH l1 Fix'edto one end ofthis shaft is an operating handle I I2. It will thus be evident that when the worm' 1 I0- is rotated by the operating handle l-2;the5worni wheel I0! is rotated, rotating therewith the cut ter head 6. This worm gearing -is-self'-1o'cking and holds automatically the cutter head against rotationin' its adjusted position: A kerf cutter supporting hanger H3 is rigidly-securedjasby screws H4, to the swingable cutter support 8,as shownin Fig. 3. The'kerf cutter 9 isherein in the form of a'coal saw and- "comprises-a relative ly thin cutter bar 1 l5 connected through-usualadjusting mechanism H6 to the hanger support H3, and having mountedfor circulation about-its margin a cutter bit carrying 1 cutter chain "I H of a'relatively narrow'design: The means fordriv ing this cutter chain for circulating; the latter about the margin of the cutter 'barx'comprisesfia bevel pinion H8 fixed to the forward 'endof the. motor power shaft I1 andme'shingyas shown, in'

Fig. 4,; with a bevel gear I l9'housed within-"the.

yoke-shaped frame I of the cutter head 8' which is herein made hollow and jolurnal'ed on the shaft.

shown. Thisshaft lfl is arranged With itS- ai= alined with'the pivotal axis of the cutter support 8 and has connectible thereto, as by a jaw clutch I23 splined to the shaft, a bevel pinion I24. This bevel pinion has clutch teeth I25. engageable with the teeth of the jaw clutch I23 and is journaled on a bearing sleeve I26 supported by the shaft I22. This bevel pinion I24 meshes with a large bevel gear I2I fixed to a shaft I29 herein arranged with its axis perpendicular to the pivotal axis I of the cutter support 8 and suitably journaled within the hanger support I I3, as shown in Fig. 3. Keyed to the outer end of this shaft I28 is a chain sprocket I29 which engages and drives the cutter chain Ill. The operating means for the jaw clutch I23 comprises a shipper yoke I30 pivotally mounted within the cutter support 8 and having a lever I3I connected by a pivoted link I32 to an eccentric pin I33 herein formed on a shaft I34 journaled within the support 8 and having an operating lever I35. A suitable pin lock I36 is provided for holding the lever I35 in its difierent positions. It will thus be seen that the cutter chain III may be connected in driving relation with the motor or remain idle at will during running of the motor.

The cutter support 8 is pivotally mounted at I on and between the arms of the yoke shaped frame I05 for swinging movement relative thereto about an axis coinciding with the axis of the shaft I22 and at right angles to' the axis of the cutter chain drive shaft I28 and the cutter head axis. This cutter support 81 is provided with lateral trunnions I40 pivotally mounted within bearing sleeves I4I supported within bearing supports I42 formed integral with the yoke shaped frame I05. The. improved mechanism for swinging the cutter support 8 relative to the yoke frame of the cutter head-to move the kerf cutter into different angularly related cutting planes with respect to the cutter head axis, herein comprises a bevel pinion I43 fixed to the inner end of the cutter chain drive shaft I28 and meshing with oppositely rotatable reverse bevels I44 and I45. These reverse bevels are selectively connectible by multiple disc clutches I46 and M1, respectively, to a shaft I48 alined with the shaft I22 and suitably journaled at its inner end within a bearing sleeve I49 supported within the shaft I22 and at its outer end within a ball bearing I50 supported within a cover or cap plate I5I detachably secured to the bearing support I42 of the yoke frame I05. The operating means for the disc clutches I46, I41 herein comprises a clutch shipper member I52 surrounding and slidably mounted on the shaft I48 between the reverse bevels I44, I and engaging at its opposite side clutch applying elements I53. For sliding the shipper member I52 axially relative to the shaft, there is provided a yoke I54 pivotally mounted at I55 on a shaft supported within the cutter support 8. One side of this yoke is provided with a slotted. portion I56 engageable with an eccentric pin I5I formed on the inner end of a shaft I58 suitably journaled Within the cutter support and having an operating lever I59.

Again referring to the cutter support swinging mechanism, and more particularly to the speed reducing means between the shaft I42 and the support 8, it will be noted that the shaft I48 is formed with an eccentric I60 having rotatably mounted thereon through a roller bearing I6I an annular member I62. This annular member is provided with a hub portion I63 journaled on a bearing sleeve I64 supported by the shaft I48 and-has formed therein, as shown in Fig. 5, a plurality of radially located chambers I65 in each of which there is slidably guided a plunger I66. ends engage in sliding abutting relation the exterior periphery of the outer race I6I of the roller bearing and are formed at their outer extremities with tooth-like projections I68 adapted to engage with a wedging action the inclined surfaces of tooth-like portions I69 formed on an annular frame II0 herein arranged in a bore III formed in the adjacent trunnion I40 of the cutter support 8 and secured to the latter as by a key. The annular'member I62 has formed on its hub portion I63 an eccentric II2 having rotatably mounted thereon, through anti-friction rollers'l I3, an annular member I I4. Formed in the annular frame H0 is a plurality of radially located chambers II5 similar to the chambers I65 above described and having similarly slidably guided therein plungers I16 similar to the plungers I66. These plungers engage at their inner ends in sliding abutting relation the exterior periphery of the annular member I14 and are formed at their outer extremities with tooth-like projections similar to the projections I68 on the plung-- These plungers at their inner ers I66 and similarly adapted to engage with a wedging action the inclined surfaces of toothlike portions III formed on an annular flange II8 herein formed integral with the cap plate I5I secured to the cutter head frame. This mechanism forms a compound speed reducing mechanism between the shaft I48 and the tiltable cutter support 8, and as the eccentrics I60, I12 are revolved by the shaft I48, the plungers I66, I16 are driven radially outwards through the chambers in the frames I62, I10 so that the ends of the plungers engage the inclined sides of the tooth-like projections I69, Ill and thereby transmit rotary motion to the annular frame II0 secured to the cutter support 8 to tilt the latter about the axis of the shaft I48 relative tothe cutter head frame. The operation of the toothlike plungers is continuous and the elements of this speed reducing mechanism form what might be termed a compound continuous wedge or heliocentric speed reducing mechanism. It will thus be seen that when one or the other of the disc clutches I46, M1 is applied, the cutter support 8, together with the kerf cutter supported thereby, may be tilted in one direction or the other about the axis I relative to the yokeshaped frame I05 of the cutter head. I

The improved mining machine is adapted to be supported on a usual transport truck during movement of the machine about the mine, and the truck driving means on the machine for effecting drive of the wheels of the transport truck herein comprises a polygonal driving element I 80 formed on the shaft 39, as shown in Fig. 7, and engageable with a polygonal socket member formed on the truck. It will thus be seen that the wheels of the transport truck on which the machine is supported may be driven at a predetermined high speed and through a wide range of relatively low speeds through the feed drive mechanism, it being possible to drive, the truck wheels at relatively low variable speeds or at a relatively high predetermined speed, as conditions may require. The operation of the improved mining machine, will be clearly apparent from the description given. When the parts are in the position shown in Figs. 1 and 2, the arm 4 is in its lowermost position with respect to the skid and the cutter head 6 is positioned to locate the kerf cutter 9 75 arm between the latter and said skid and including relatively rotatable screw and nut elements, a guideway on the bottom of said arm in which one of said elements is guided, and a I link connecting said guided element with said skid.

8. In a mining machine, a portable base, an arm pivotally mounted on said base for swinging movement in a vertical direction relative thereto, a kerf cutter carried by said arm, and motor operated means for swinging said arm relative to said base including a screw shaft arranged beneath and extending longitudinally of said arm, a nut engaging said screw shaft and guided on said arm, and a link connecting said nut to said base.

9. In a mining machine, a portable base, an arm pivotally mounted on said base for swinging movement in a vertical direction relative thereto, a kerf cutter carried by said arm, and motor operated means for swinging said arm relative to said base including a screw shaft arranged beneath and extending longitudinally of said arm, a nut engaging said screw shaft and guided on said arm, a link connecting said nut to said base, and motor operated reversing gearing carried by said arm for rotating said screw shaft in either of opposite directions.

10. In a mining machine, a portable base, an arm pivotally mounted at its rear end on the rearward portion of said base to swing in a vertical direction with respect thereto, said arm overlying said base, a kerf cutter carried by the forward end of said arm and projecting forwardly in advance of said base, and means for swinging said arm vertically about its pivot relative to said base to vary the elevation of said kerf cutter comprising a screw and nut adjusting mechanism arranged between the bottom of said arm and said base and including an element pivotally connected to said base and means mounted on said arm and swingable therewith for actuating said screw and nut mechanism.

11. In a mining machine, a portable base, an arm pivotally mounted at its rear end on the rearward portion of said base to swing in a vertical direction with respect thereto, said arm overlying said base, a kerf cutter carried by the forward end of said arm and projecting forwardly in advance of said base, and means for swinging said arm vertically about its pivot relative to said base tovary the elevation of said kerf cutter comprising a screw and nut adjusting mechanism arranged between the bottom of said arm and said base, said adjusting mechanism ineluding a screw journaled on the bottom of said arm and a cooperating axially movable nut.

12. In a mining machine, a portable base, an arm pivotally mounted at its rear end on the rearward portion of said base to swing in a vertical direction with respect thereto, said arm overlying said base, a kerf cutter carried by the forward end of said arm and projecting forwardly in advance of said base, and means for swinging said arm vertically about its pivot relative to said base to vary the elevation of said kerf cutter comprising a screw and nut adjusting mechanism arranged between the bottom of said arm and said base, said adjusting mechanism including a screw journaled on the bottom of said arm, a cooperating axially movable nut and a link pivotally connected between said nut and said base.

13. In a mining machine, a skid adapted to rest upon and slide in any direction over the mine floor, an arm overlying said skid and at its rearward extremity pivotally mounted on the rearward portion of said skid to swing in a vertical direction with respect thereto, a kerf cutter carried at the forward end of said arm and projecting forwardly in advance of said skid, and devices for swinging said arm about its pivot relative to said skid to vary the elevation of said kerf cutter comprising a screw and nut adjusting mechanism underlying said arm between the latter and said skid and including relatively adjustable screw and nut elements and a cooperating element pivotally connected to said skid, and means mounted on said arm and swingable therewith for effecting relative adjustment of said screw and nut elements.

14. In a mining machine, a skid adapted to rest upon and slide in any direction over the mine floor, an arm overlying said skid and at its rearward extremity pivotally mounted on the rearward portion of said skid to swing in a ver tical direction with respect thereto, a kerf cutter carried at the forward end of said arm and projecting forwardly in advance of said skid, and motor operated devices for swinging said arm about its pivot relative to said skid to vary the elevation of said kerf cutter comprising a screw and nut adjusting mechanism underlying said arm between the latter and said skid, said adjusting mechanism including a screw journaled on the bottom of said arm, a cooperating axially movable nut, and means carried by said arm for rotating said screw.

15. In a mining machine, a skid adapted to rest upon and slide in any direction over the mine floor, an arm overlying said skid and at its rearward extremity pivotally mounted on the rearward portion of said skid to swing in a vertical direction with respect thereto, a kerf cutter carried at the forward end of said arm and projecting forwardly in advance of said skid, and motor operated devices for swinging said arm about its pivot relative to said skid to vary the elevation of said kerf cutter comprising a screw and nut adjusting mechanism underlying said arm between the latter and said skid, said adjusting mechanism including a screw journaled on the bottom of said arm, a cooperating axially movable nut and a link pivotally connected between said nut and said skid, and means carried by said arm for rotating said screw.

16. In a mining machine, a skid adapted to rest upon and slide in any direction over the mine floor, an arm overlying said skid and pivotally mounted on said skid to swing in a vertical direction relative thereto, a kerf cutter carried by the forward end of said arm and projecting forwardly in advance of said skid, and motor operated means for swinging said arm vertically about its pivot relative to said skid including a screw journaled on said arm beneath the latter, a motor carried by said arm for rotating said screw, a nut threaded on said screw, and a link pivotally connected at one end to said nut and at its opposite end to said skid.

17. In a mining machine, a skid adapted to rest upon and slide in any direction over the mine floor, an arm overlying said skid and pivotally mounted on said skid to swing in a vertical direction relative thereto, a kerf cutter carried by the forward end of said arm and projecting forwardly in advance of said skid, and motor operated means for swinging said arm vertically about its pivot relative to said skid including a screw journaled on said arm beneath the latter, a motor carried by said arm for rotating said screw, means on the bottom of said arm providing a longitudinal guideway in parallelism with said screw, a nut guided on said guideway and threadedly connected to said screw, and a link pivotally connected at one end to said nut and at its opposite end to said skid.

18. In a mining machine, a portable base, an arm pivotally mounted on said base to swing in a vertical direction with respect thereto, said arm overlying said base, a kerf cutter carried by the forward end of said arm and projecting forwardly in advance of said base, and means for swinging said arm vertically about its pivot relative to said base to vary the elevation of said kerf cutter comprising mutually mechanically interengaging, toothed, arm swinging elements.

spectively, and means mounted on said am and swingable therewith for efiecting relative rectilinear movement between said arm swinging elements.

19. In a mining machine, a portable base, an arm pivotally mounted on said base to swing in a vertical direction with respect thereto, said arm overlying said base, a kerf cutter carried by the forward end of said arm and projecting forwardly in advance of said base, and means for swinging said arm vertically about its pivot relative to said base to vary the elevation of said kerf cutter comprising mutually mechanically interengaging, toothed, arm swinging elements having relative rectilinear movement to effect arm swing and arranged between said arm and base, said elements operatively connected to said arm and base respectively, and one of said elements mounted on the bottom of said arm to swing therewith.

MORRIS P. HOLMES.

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