US2761664A - Multiple rotor head mounting for mining machine - Google Patents

Description

S. BOWMAN Sept. 4, 1956' MULTIPLE ROTOR HEAD MOUNTING FOR MINING MACHINE l2 Sheets-Sheet 1 Filed July 21. 1.953

. INVENTOR.

- SPENCER BOWMAN FHUHWIF.

A T TOR/V5 Y S. BOWMAN Sept. 4, 1956 MULT PLE: ROTOR HEAD MOUNTING FOR MINING MACHINE 12 SheeIs-Sheet 2 Filed July 21, 1953 IN V EN TOR.

8 PE NGE R BOWMAN A TTOR/VE Y Se t. 4, 1956 s. BOWMAN 2,751,664

MULTIPLE ROTOR HEAD MOUNTING FOR MINING MACHINE Filed July 21.. 1953 12 Sheets-Sheet 3 IN V EN TOR. SPENCER BOWMAN ATTORNEY S. BOWMAN Sept. 4, 1956 MULTIPLE ROTOR HEAD MOUNTING FOR MINING MACHINE Filed July 21. 1953 12 Sheets-Sheet 4 INVENTOR. SPENCER BOWMAN ATTORNEY S. BOWMAN Sept. 4, 1956 MULTIPLE ROTOR HEAD MOUNTING FOR MINING MACHINE Filed July 21, 1953 12 Sheets-Sheet 5 (/33 w zwkz . INVEN TOR. F/G- SPENCER BOWMAN S. BOWMAN Sept. 4, 1956 MULTIPLE ROTOR HEAD MOUNTING FOR MINING MACHINE",

Filed July 21, 1953 12 Shfs-Sheet e N VEN TOR.

BY sPmvcm BOWMAN A T TOR/VE Y BOWMAN Sept. 4, 1956 l2 Sheets-Sheet 7 Filed July 21I 1953 M3 v3 M3 9% vQ m2 O INVENTOR. SPENCER BOWMAN A r TORNEY S. BOWMAN Sept. 4, 1956 MULTIPLE ROTOR HEAD MOUNTING FOR MINING MACHINE Filed July 21, 1953 12 Sheets-Sheet 8 \8 m8 $8 0 8 PS INVENTOR. SPENCER BOWMAN A T TOR/V5 Y s. BOWMAN 2,761,664

12 Sheets-Sheet 9 Sept. 4, 1956 MULTIPLE ROTOR HEAD MOUNTING FOR MINING MACHINE Filed July 21, 1953 .wv 5 R. w R. T I I N V; I I 1 INVEN TOR. SPENCER BOWMAN A TTORNEY Q A Q m NN A QM m S. BOWMAN Sept. 4, 1956 MULTIPLE ROTOR HEAD MOUNTING FOR MINING MACHINE Filed July 21, 1953 12 Sheets-Sheet l0 3 mt NV kw w INVENTOR.

SPENCER BOWMAN A TTOR/VEY S. BOWMAN Sept. 4, 1956 MULTIPLE ROTOR HEAD MOUNTING FOR MINING MACHINE l2 Sheets-Sheet 11 Filed July 21, 1953 A T TORNE Y Sept. 4, 1956 BOWMAN 2,761,664

MULTIPLE ROTOR HEAD MOUNTING FOR MINING MACHINE Filed July 21. 1953 12 Sheets-Sheet 12 FIG. /7

INVENTOR.

SPENCER BOWMAN United States Patent MULTIPLE ROTOR HEAD MOUNTING FOR MINING MACHINE Spencer Bowman, Bay Village, Ohio, assignor, by mesne assignments, to Westinghouse Air Brake Company, a corporation of Pennsylvania Application July 21, 1953, Serial No. 369,311

9 Claims. 1 (Cl. 262-7) This invention relates broadly to continuous mining machines, but more particularly to a mining machine of the multiple rotor or cutting head type and to the means for efliciently supporting and adjusting such heads.

One object of this invention is to provide such a machine with simple and efficient means through which the multiple rotor or cutting heads thereof are readily retractable intoinoperative position within the confine of the machine, or extendible to an operative position adapted to produce a cut wider than the normal width of the machine.

Another object of this invention is to produce an adjustable mounting for each cutting head of said machine, which is of simple and strong construction, capable of withstanding the relatively high cutting thrust to which it is subjected.

Another object of this invention is to produce a relatively simple and comparatively inexpensive mechanism for effecting lateral extension or retraction of the cutting heads, the mechanism including self-locking means preventing accidental collapse or retraction of the heads.

Another object of this invention is to provide such machine with a supporting frame topped by a flat rigid plate extending forwardly from the front end thereof and having cutting heads extending therebeyond'from supporting arms protectively mounted on the underside of the plate.

Another object of this invention is to provide the rotary cutting heads of such machine with hollow supporting arms having housed therein rotation transmitting means through which rotary motion is transmitted to the heads.

Other objects of this invention will be apparent from the following detailed description wherein similar characters of reference designate corresponding parts, and wherein:

Figure 1 is a top plan view of a' continuous mining machine embodying the invention and showing the rotor heads in a retracted nonoperative position.

Figure 2 is an enlarged plan view of the front end of the machine showing the rotor heads in an extended operative position.

Figure 3 is a side elevational view of the machine.

Figure 4 is an enlarged longitudinal sectional view taken on line 4-4 in Figure 2 and looking in the direction of the arrows.

Figure 5 is an enlarged longitudinal sectional view taken on line 5-5 in Figure 4. 1

Figure 6 is an enlarged sectional view of the innner end of the rotor arm shown in Figure 4.

Figure 7 is an enlarged view of the underside of the top plate of the machine as viewed from the arrows 7-7 in Figure 4, showing the cutting head supporting arms in extended position.

Figure 8 is a view similar to Figure 7, but with the arms in retracted position.

Figure 9 is an enlarged cross-sectional view taken on line 9-9 in Figure 7. 1

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Figure. 10 is an enlarged cross-sectional view taken on line 10-10 in Figure 7.

Figure 11 is an enlarged longitudinal sectional view taken on line 11-11 in Figure 7.

Figure 12 is an enlarged sectional view taken on line 12-12 in Figure 7.

Figure 13 is a front elevational view of the rotors in an extended operative position.

Figure 14 is a view similar to Figure 12 but with the rotors in a retracted non-operative position.

Figure 15 is an enlarged view of the gear box shown in Figure 3, but with its lid removed.

Figure 16 is an enlarged cross-sectional view taken on line 16-16 in Figure l.

Figure '17 is an enlarged cross-sectional view taken on line 17-17 in Figure 3.

Shown in the drawings, there is the general outline of a continuous mining machine to which the invention applies. As shown in Figure 3, this machine includes an elongated relatively low frame 20 supported between a pair of tractor treads 21 through which the entire machine is normally carried. Among other things, this frame carries a relatively thick top plate 22 having its portion adjacent the front end of the machine enlarged as at 23 to an extent denoting substantially the greatest width of the machine. This plate carries all the rotor heads and their supporting arms about to be described, and is therefore an important part of this invention, but since the means through which it is mounted on the frame 20 is not a part of this invention, no illustration thereof is thought necessary. However, it may be stated that the top plate 22 is preferably fixed to two parallel elevator bars extending longitudinally underneath its narrower or inner portion, which bars are connected to the frame 20 by a system of links forming a parallelogram, with the top plate 22 adjustable in height, by hydraulic means, within a range of about 5".

As shown in Figure 3, the, top plate 22 is substantially horizontal with its enlarged end portion 23 extending longitudinally well beyond the front end of the frame 21) to form a rigid overhang underneath of which are movably mounted the arms 24 of a plurality of rotor heads 25, six of which are shown in the drawings. All rotor heads are identical, and as shown in Figure 5, each comprises a T-shaped housing 26 having a burster 27 fixed on the cross arm 28 thereof coaxially with its axis of rotation by bolts 29. The tubular leg 30 of the housing 26 forms the driving axle for its cross arm 28. It is adequately supported on a spider 31 for rotation relative thereto, by two tapered bearings 32 and 33 adapted to also resist the axial thrust to which the rotor head is subjected while in operation. Spider 31 is fixed in the non-rotatable outer end 34 of the arm 24, and between the bearings 32 and 33, it carries on cross shafts 35 three planet gears 36 in mesh with a sun gear 37 which forms the output end of a driving shaft 38. The planet gears 36 are also in mesh with a ring gear 39 formed as an integral part of the tubular leg or driving axle 30. Thus it will be understood that rotation of the shaft 38 is transmitted to the rotor head 25 and its burster 27 on the longitudinal center axis of the latter. Since this rotation transmitting mechanism is more fully described in my co-pending application Serial No.

343,764, now abandoned, no further description is thought tends longitudinally and forwardly therefrom. In practice, it may be of any desired type, such as carrying rotary cutters or the like, all adapted to cut a circular kerf in the coal being mined. Fastened to the free end of the shank 41 by a bolt 43, there is the tail piece 44 of a nut 45 which cooperates with a screw 46 extending longitudinally in the cross arm 38, parallel to but offset from the shank 41, and adequately journaled within a bearing 47. A ball bearing 48 is mounted in the tubular leg 30 adjacent the end of the spider 31, and has journaled therein a tubular shaft 49 which extends into the spider cavity 40 where it is operatively surrounded by a hydraulically operated brake 50, and through which it may be locked to the spider and thereby made stationary. Extending through and journaled within the shaft 49, there is a smaller shaft 51 which projects therefrom into the bottom of the cavity 40 where it is operatively surrounded by a hydraulically operated brake 52. Shaft 51 has fixed to its outer end a first bevel gear 53 and the shaft 49 a second bevel gear 54. The first bevel gear is in mesh with a third bevel gear 55 fixed on the screw 46, while the second bevel gear 54 is in mesh with an idler pinion 56 carried on a shaft 57, which idler is in mesh with a fourth bevel gear 58 also fixed on the screw 46.

From the foregoing, it will be understood that as the rotor head 25, which includes the burster 27 and cutting bar 42, rotates on its own axis, the bevel gears 55 and 58, normally stationary relative to their own common axis, revolve with the screw 46 about the rotary axis of the rotor head, thereby causing the gears 55 and 58 to impart rotation to the gears 53 and 54 in opposite directions by virtue of the idler 56. As long as the brakes 50 and 52 remain inoperative,.the cutter bar 42 revolves about the rotary axis of the head 25 to cut a kerf of a uniform diameter. When it is desired to radially retract or extend the cutter bar, that is, change the diameter of the kerf being cut thereby, it is only necessary to operate the brake 50 or 52, thereby locking gear 53 or 54 against rotation. In such instance, the revolving motion of the gears 55 and 58 about stationary gears 53 or 54, imparts rotation to the screw 46 in one or the other direction, and to the shank 41 through the nut 45, effects inward or outward movement of the cutting bar 42. Since the mechanism just above referred to is more fully described in the co-pending application Serial No. 355,073, no further explanation is believed necessary, other than pointing out that since the radial adjustment of the cutter bar 42 is responsive to the rotation of the rotor head 25, this adjustment can be made as the cutting operation progresses to vary the diameter of the kerf being cut.

The end of the driving shaft 38 opposite the sun gear 37, is enlarged to form a ring gear 60 adequately supported by a ball bearing 61 mounted in the outer end 34 of the arm 24. This ring gear has rotation imparted thereto by a plurality of planet gears 62 mounted on cross shafts 63 carried by a stationary spacer 64. Coaxially with the driving shaft 38, there is a shaft 65 supported by two ball bearings 66 mounted in the stationary spacer 64. This shaft has an integral sun gear 67 in mesh with the planet gears 62, and a bevel gear 68 fixed on one end thereof by a key 69.

As shown in Figure 2, the arms 24 of the rotor heads 25 extend angularly and inwardly therefrom with respect to the longitudinal center axis of the machine. The two outboard rotors have arms converging therefrom toward each other at equal and relatively sharp angles with respect to the axis of rotation of the rotors. The legs of the intermediate rotors, similarly converge toward each other but at lesser angles, and so do the legs of the inboard rotors, the angle of which is relatively small. Except for their angular postion relative to their carrying rotors, all arms 24 are substantially alike. Preferably each comprises a tubular member 70, which as shown in Figure 5, extends angularly from the spacer 64 and adjacent thereto is provided with a cross wall 71 carrying a ball bearing 72 in which is journaled one end of a drive shaft 73. A bevel gear 74, in mesh with the bevel gear 68, is keyed on the end of the shaft 73. As shown in Figures 4 and 6, the other or inner end of the tubular member is also provided with an integral cross wall 75 accommodating a ball bearing 76 in which is journaled the other end of the shaft 73, which beyond the cross wall 75 also has fixed thereona right angle bevel gear 77. Beyond the cross wall 75 the tubular member 70 is formed with a relatively thick integral bearing plate 78 extending longitudinally therefrom parallelly with the under side of the top plate 22, and rigidly supported by two side walls 79. Within the vertical plane passing through the longitudinal center axis of the shaft 73, the top plate 22 has a bore 80 extending vertically therethrough to receive a relatively large bushing 81, which is substantially flush with the upper side of the plate, but protrudes from its underside through the bearing plate 78. The bushing is axially locked in one direction by a split ring 82 engaging the bottom of a counterbore 83 formed on the upper side of the plate 22, and in the other direction by a split ring 84 engaging the bearing plate 78. Holding the bearing plate 78 on the bushing 81 and against the underside of the top plate 22, there is a ledge 85, see Figure 4, substantially parallel to the underside of the top plate, on which rests the flat band 86 formed on the inner end of the arm parallelly to the bearing plate 78. The ledge 85, which extends transversely of the plate 22 and is common to all arms 24, has a back wall 87 extending vertically therefrom rigidly secured to the underside of the plate 22 by any suitable means, not shown. Thus it will be understood that the inner end of each arm 24 is pivotally mounted on the bushing 81 between two parallel guides defined by the underside of the plate 22 and the ledge 85. A shaft 88 extends through the bushing 81 where it is journaled in bearings 88', and has fixed on its lower end a right angle bevel gear 89 in mesh with the gear 77, and on its upper end, above the top plate 22, a relatively large spur gear 91, fixed thereon by a key 90.

It will be understood that the inner ends of the rotor arms 24 are all as above described and shown in Figure 6, with the spur gear 91 thereof in interengagement as clearly shown in Figure 1, thus resulting in the rotor heads 25 rotating alternately in different directions. Rotation of the gears 91 is derived from an electric motor 92 of sufiicient capacity, shown schematically in Figure 3 as mounted on the side of the frame 20. As shown in Figure 17, this motor has an output shaft 93 extending into a gear box 94 through supporting bearings 95, and has fixed to its free end by a key 96 a spur gear 97. Gear box 94, which has a removable lid 98, extends diagonally from the shaft 93 of motor 92 to the underside of the top plate 22 as clearly shown in Figure 3. With reference to Figure 15 which shows the gear box 94 with its lid removed, it will be seen that the input spur gear 97 is transmitting rotation to an output gear 99 through two idlers 100 and 101 mounted on stub arbors 102. As shown in Figure 16, the output gear 99 is fixed on a shaft 103 by a key 104,

g which shaft is journaled within ball bearings 105 and extends through the lid 98 of the gear box to receive a right angle bevel gear 106 fixed thereon by a key 107. Within a vertical plane passing through the axis of the shaft 103, the top plate 22 has a bore 108 extending therethrough with two ball bearings 109 mounted therein, in which is journaled a shaft 110. Fixed on the lower end of this shaft, on the underside of the plate 22, by a key 111, there is a bevel gear 112 in mesh with the bevel gear 106, and on its upper end above the plate 22, there is a spur gear 113 fixed by a key 114. As shown in Figure l,

r the spur gear 113 is in mesh with an idler 115 which in turn is in mesh with one of the gears 91, the idler 115 being mounted on the plate 22 substantially as the gears 91 and 113. Preferably all gears 91, 113 and 115 on the upper side of the top plate 22, are protectively housed in a gear box 116, the removable lid 117 of which is shown in Figure 16 but has been left off in Figure 1.

Pivotal movement of the arms 24 on the bushings 81, that is, their inward or outward movements, are effected by a system of links clearly shown in Figures 7 and 8, both of which show the underside of the plate 22 as viewed from the arrows 77 in Figure 4. In order to more clearly show the linkage about to be described, the ledge 85, gears and shafts shown in Figure 4 have been left out of Figures 7 and 8. The link system and its actuating means include a hydraulic cylinder 120 fixed to the underside of the plate 22, having a piston (not shown) slidable therein and connected to a piston rod 121 for imparting forward or backward movements thereto. In practice the cylinder 120 is operatively connected to a source of hydraulic fluid such as a pump, and is actuated at the will of the operator by manipulation of adequate valve means. Piston rod 121 extends longitudinally of the plate 22 substantially mid-way between the sides thereof and between the two inboard arms 24a. Adjacent the cylinder 120, the piston rod is cylindrical, but thereafter it is formed of two spaced superposed strips 122 fixed to the cylindrical portion of the rod by a cross pin 123, see Figure 11, and extending longitudinally and coaxially therefrom. A second cross pin 124 pivotally connects the superposed ends of two arcuated links 125 to the rod or strips 122, which links extend in opposite directions from the central axis of the rod. Also located between the piston rod strips 123, is the inner end of a straight link 127 which extends longitudinally and coaxially therefrom. Between the strips 123, this link is formed with two spaced longitudinal slots 128 having fitted therein cross pins 129 carried by the strips 122, which pins maintain the link coaxially with the strips and are engageable with the bottom of the slots for transmitting longitudinal motion to the link 127. The outer end of the link 127 is pivotally connected by a cross pin 130 to two lateral links 131 extending therefrom in opposite directions, which have their other ends pivotally connected by cross pins 132 to the inner sides of the inboard arms 24a at a place near the bottom of their straight portions leading from their rotor heads 25.

With reference to the arcuated links 125, each constitutes the primary element of a linkage actuating the intermediate arms 24b and the outboard arms 24c. As shown in Figures 7 and 8, the end of each link 125 remote from the piston rod 121 is forked to fit over a bell-crank lever plate 133 where it is pivotally connected by a cross pin 134, see Figure 10, the plate being pivotally carried by a stud 135 on a boss 136 raised from the underside of the top plate 22, see Figure 9. A relatively long link 137, has one forked end pivotally connected to the plate 133 by a pin 138, and leads therefrom between the arms 24a and 24b to leave its other end pivotally connected by a pin 139 to two lateral links 140 and 141 extending in opposite directions and pivotally connected to the inner sides of the inbound and intermediate arms by cross pins 142. A third link 143 has one of its forked ends also pivotally connected to the plate 133 by a cross pin 144, while its other forked end is similarly connected to a second bell-crank lever plate 145 by a cross pin 146, which like the plate 133 is pivotally carried on the underside of the plate 22 by a stud 147. A relatively long link 148, leads from this plate 145 Where its forked end is pivotally connected by a pin 149, and extends between the intermediate and outboard arms 24b and 240 respectively to terminate in a pivotal connection 150 with two lateral links 151 and 152, which extend therefrom in opposite directions and are pivotally connected by cross pins 153 to the opposite sides of the intermediate and outboard arms 2% and 240. As shown in Figure 12, the lateral links pivotally connected to the rotor arms, are relatively wide to assure sufficient strength and rigidity. Preferably the lateral links 141 and 152 have an integral lug 157 forming a stop engageable with the undersides of the links 151 and 152 respectively for limiting outward movement of the links 137 and 148 and consequently the outward movement of the rotor arms.

As shown in Figures 2 and 4, the inboard and intermediate rotor arms 24a and 24']; have, adjacent the base of their rotor heads, their upper sides formed with a laterally extending guide-way 154 having parallel side walls 155 between which is fitted the front end portion 156 of the top plate 22, thereby providing a sliding supporting connection or guide between the front end of the plate and the rotor arms. As shown in Figure 1 the leading end of the top plate is especially shaped to enable free lateral movement of the rotor arms without interference with the guide-ways 154.

In the operation of the machine, it is understood that rotation is imparted to the first spur gear 113 on top of the plate 22 by the electric motor 92, it being transmitted therefrom through the .spur gears 97, 100, 101 and 99, see Figure 15, and bevel gears 106 and 112, Figure 16. From the gear 113, rotation is transmited to the interengaging gears 91 through the idler 115. From each gear 91, rotation is transmited to a rotor head 25 through bevel gears 89 and 77, Figure 6, shaft 73, and the transmission mechanism heretofore described and shown in Figure 5, which briefly includes bevel gears 74 and 68, planetary train including sun gear 65, planet gears 62 and ring gear 60, floating shaft 38 and a second planetary train including sun gear 37, planet gears 36 and ring gear 39, the latter being an integral part of the rotor head housing 26. Since the gears 91 are directly connected to each other, it is obvious that any two adjoining gears, as well as any two adjoining rotor heads 25, will rotate in opposite directions. While the cutter arms 42 are all substantially alike, the ones rotating in the same direction have their leading cutting edges disposed of course at from the ones rotating in the other direction, while the trailing edge of each cutter is shaped and spaced relative to the leading edge in a manner enabling free cutting of a kerf without binding or dragging. In order to enable rotation of the cutter arms 42 without interference from the cutter bar of any adjoining rotor head, the cutter bar shanks 41 are first positioned as shown in Figure 13, that is with the shanks of the rotor heads B, D and F rotating in the counterclockwise direction being exactly in the same position, and the cutter bar shanks of the rotor heads A, C and D rotating in the clockwise direction being exactly at right angles from the other shanks. Since the rotary speed of each rotor is exactly alike, it will be understood that after having been initially positioned as above described and operatively connected to their rotation imparting mechanism While in that position, the cutter bar shanks of one set of rotor heads such as B, D and F, will remain synchronized at 90 from the ones of the heads A, C and E. With reference to the cutter bars 42, they are preferably located so that when their shanks are substantially parallel, that is positioned diagonally at 45 from the position shown in Figure 13, each adjoining cutter bar will be at substantially 180 from each other, thereby enabling the heads 25 to assume substantially the positions shown in Figure 14 while in a retracted position.

During rotation of the rotor heads 25, that is during mining operations when the entire machine is fed by the tractor treads 21 to the face being mined, the rotor arms 24a, 24b and 240 are in the extended position shown in Figure 7 to position the rotor heads 24 as shown in Figure 13. During the extended position of the arms, the piston rod 121 is maintained at the end of its forward stroke by the hydraulic pressure acting on its piston in the cylinder 120, thereby maintaining the link 127, through the pins 129 engaging one end of the slots 128,

at the end of its forward travel and the links 125 at the end of their inward travel, and resulting in the other links to be maintained in the position shown in Figure 7. In this instance the lateral links 131 are substantially at right angles with their actuating links 127, that is in dead center relation therewith, consequently rendering ineffective any forces to which the arms 24a may be subjected tending to cause their collapse or inward movement while the set of lateral links 140, 141 and 151, 152 are similarly located relative to their actuating links 137 and 148 respectively, to safeguard against any possible collapse of their supporting arms and make their locks 157 effective against such collapse, they are preferably located somewhat beyond the dead center position. Thus it will be understood that in addition to imparting pivotal movement to the rotor arms, the system of links, and more particularly the lateral links also act as a locking device for preventing accidental inward movement or collapse of the arms.

When moving the machine about the mine, and especially when retracting it from the face, in order to provide sufiicient clearance for the machine and enable it to be moved about with limited amount of interference from mine props and the like, it is advantageous to retract the rotor heads 25 Within the confines of the machine. To that end the rotation of the rotor heads 25 are stopped to position the cutter blade shanks 41 or cross arms 28 cf the housing 26, parallel with each other, that is obliqueiv at an angle of about 45 with a plane coincident with their axes of rotation, thereby positioning any two adjoining cuter blades at substantially 180 from each other. Before retraction of the drill units, and while the rotor heads are still rotating, it is desirable to retract all cutter bars 42 to their innermost position by operating one or the other of the brakes 50 or 52. Since the radial adjustment of each cutter bar is effected by virtue of its rotation, radial retraction of the bar relative to its head cannot be made when the head is not rotated. Thereafter the drill units may be retracted by reversing the hydraulic action on the piston in the cylinder 120 to cause inward movement of the piston rod 121 to the cosition shown in Figure 8. Because both inboard arms 24 are retracted toward each other, the length of their pivotal travel is about one-half that of the other arms, consequently it is necessary for the inboard arms to travel a shorter distance than the other arms for a given stroke of the piston rod 121. To that end, the initial inward movement of the piston rod is transmitted only to the intermediate and outboard arms 24b and 240 through the links 125, while the link 127 remains stationary by virtue of the pins 129 sliding in the slots 128. As the arms 24b and 240 move substantially one-half their possible inward travel, the pins 129 reach the end of the slots 128 to move the link 127 inwardly and impart inward travel to the inboard arms to retract them with the other arms to the position shown in Figure 8. With reference to the intermediate and outboard arms 24:) and 24c, it is obvious that the inward movement of the links 125 effects the pivotal movements of the bell-crank lever plates 133 on the pivot 135 in opposite direction away from the arms and the inward movement of the actuating links 137, which in turn effects the collapse of the lateral links 140 and 141. Pivotal movement of the plates 133 is transmitted to the plates 145 through the links 543, to effect the inward movement of the actuating links 148 and the collapse of the lateral links 151 and 152.

Because of the angular shape of the rotor arms, which in the extended position causes their inner portions to converge toward each other, and their outer portions including the rotor heads 25 to be substantially parallel, it is possible to retract them within the confines of the machine to produce the compact arrangement shown in Figure 8. When retracted, it will be seen that the side walls of any two adjoining arm inner portions are substantially parallel but with suflicient space between them to accommodate the longitudinal links 127, 137 and 148, the power actuated primary link 121, and the collapsed lateral links. In their retracted position, the outer portions of the arms including the rotor heads, are converging toward their free ends as clearly shown in Figures 1 and 14, with the shanks 41 of the cutter blades 42, or more particularly with the cross arms 28 of the housings 26, closely fitted alongside of each other to form the compact arrangement clearly shown in Figure 14.

When it is desired to again spread the rotor heads, the above described operation is repeated in reversed order, that is the piston in the cylinder is hydraulically actuated to elfect the outward movement of the piston rod 121. In this instance the links move initially with the rod to impart pivotal movement to the plates 133 and toward the inner ends of the arms and effect outward movement of the longitudinal links 137 and 143. At the same time the pins 129 slide in the slots 128 without imparting motion to the link 127, thereby enabling the inboard arms 24a to remain retracted temporarily as the other units are gradually extended. As the latter reach about one-half of their outward travel, the pins 129 reach the ends of the slots 128 for imparting outward movement to the link 127 and inboard arms 24a.

Although the foregoing description is necessarily of a detailed character in order to completely set forth the invention, it is to be understood that the specific terminology is not intended to be restrictive or confining and it is to be further understood that various rearrangements of parts and modification of structural detail may be resorted to without departing from the scope or spirit of the invention as herein claimed.

I claim:

1. In a mining machine, a supporting frame, a plurality of pivotally movable rotor heads laterally spaced in operative position including two inboard heads one on each side of the longitudinal center axis of said frame, said heads adapted to be moved laterally inward against each other into inoperative position by virtue of their pivotal movement, the inward travel of said inboard heads being shorter than that of the others, and means to effect said pivotal movement with delayed action for said inboard heads.

2. In a mining machine, a supporting frame, a plurality of rotor heads laterally spaced in operative position including two inboard heads one on each side of the longitudinal center axis of said frame, supporting arms for said heads pivotally connected to said frame, said heads adapted to be moved laterally inward against each other into inoperative position upon pivotal movement of said arms, the inward travel of said inboard heads being shorter than that of the others, and means including a system of links operatively connected to said arms to effect their pivotal movement with delayed action for the arms of said inboard heads.

3. In a mining machine, an elongated supporting frame, a plurality of side by side rotor heads on each side of the longitudinal center axis of said frame extending longitudinally beyond one end of said frame and adapted for lateral movement toward and away from each other, a carrying arm for each of said heads pivotally connected to said frame to eifect said lateral movement, and power means connected to said arms to effect their pivotal movement resulting in lateral movement of the heads on one side of said center axis in a direction opposite to that of the heads on the other side of said axis, said arms being shaped to enable retraction of said heads within the width of said frame upon said lateral movement toward each other and to enable at least two of said heads to be positioned outside of the width of said frame for rotation on parallel axes upon said lateral movement away from each other.

4. In a mining machine, an elongated substantially horizontal supporting frame, a plurality of rotor heads extending longitudinally beyond one end of said frame including an inboard and an outboard head on each side of the longitudinal center axis of said frame, a supporting arm for each of said heads pivotally connected to said frame, each of said arms forming intermediate its ends an inner obtuse angle, said angles being smaller for the arms supporting said outboard heads than for the arms supporting said inboard heads whereby said heads upon maximum outward pivotal movement of said arms are positioned for rotation on axes parallel to said center axis, and means to limit the extent of said outward pivotal movement.

5. In a mining machine, an elongated substantially horizontal supporting frame, a plurality of rotor heads extending longitudinally beyond one end of said frame including an inboard and an outboard head on each side of the longitudinal center axis of said frame, a supporting arm for each of said heads having an outer portion coaxial with the axis of rotation of its head and an inner portion connected to said frame for pivotal movement on a substantially vertical axis, said outer and inner portions forming an obtuse angle facing said center axis, said angles being smaller for the arms supporting said outboard heads than for the arms supporting said inboard heads whereby said heads upon maximum outward pivotal movement of said arms are positioned for rotation on parallel axes, and means to limit the extent of said outward pivotal movement.

6. In a mining machine, an elongated substantially horizontal supporting frame, an arm on each side of the longitudinal center axis of said frame, a pivotal connection between the inner end of said arm and said frame, both arms extending longitudinally beyond the forward end of said frame, a rotor head mounted on the outer end portion of each arm for rotation on the center axis of said portion, each head being extendible into a position laterally outward of said pivotal connection relative to the longitudinal center axis of said frame, said arms being shaped whereby said heads when extended into said position are located for rotation on parallel axes.

7. In a mining machine, an elongated supporting frame, a substantially flat horizontal plate constituting the upper side of said frame, a plurality of arms on each side of the longitudinal axis of said frame, pivotal connections between the inner ends of said arms and the underside of said plate enabling lateral movement of said arms under said plate, the outer end portions of said arms extending longitudinally beyond said plate and having their center axes maintained within a single substantially horizontal plane by virtue of said pivotal connections, rotor heads mounted on said outer end portions for rotation on said center axes, power driven rotary means longitudinally through said arms drivingly connected to said heads, power means connected to said arms for imparting pivotal movement thereto to shift said rotor heads into operative positions laterally further away from said longitudinal axis than the pivotal connections of their supporting arms with said frame, said arms being shaped in a manner causing the center axes of said outer end portions to be parallel during the operative positions of said heads.

8. In a mining machine, an elongated supporting frame, a plurality of arms having their inner ends pivotally connected to said frame, and their outer end portions extending longitudinally beyond one end of said frame, a rotor head operatively mounted on the outer end portion of each of said arms, said arms being shaped whereby upon their inward pivotal movement their outer end portions are adapted to nest toward each other within the width of said frame and upon their outward pivotal movement of their outer end portions are positionable with their center axes parallel with each other, and power driven means operatively associated with said arms for imparting said pivotal movement thereto.

9. In a mining machine, a supporting frame, a substantially flat plate constituting the upper side of said frame, an arm extending longitudinally beyond one end of said plate, means connecting the inner end of said arm to the under side of said plate for pivotal movement of the arm about an axis perpendicular to said plate, ledge means carried by said plate maintaining said inner end against the under side of said plane, a supporting connection between said one end of said plate and said arm enabling said pivotal movement, and a rotor head operatively mounted on the outer end portion of said arm.

References Cited in the file of this patent UNITED STATES PATENTS 504,179 Stanley Aug. 29, 1893 674,415 Hough May 21, 1901 1,357,510 Pedulla Nov. 2, 1920 1,984,373 Holmes Dec. 18, 1934 2,379,137 Fencht June 26, 1945 2,415,205 Gartin Feb. 4, 1947 2,675,996 Gunning Apr. 20, 1954

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