636,384. Mining-machines. BRITISH JEFFREY-DIAMOND, Ltd. March 25, 1946, No. 9221. Convention date, April 6, 1945. [Class 68 (i)] [Also in Groups XXIV, XXIX, XXXIV and XXXVII] A mining machine for use in low seams comprises a rotor mounted within a motor frame wholly or partially of magnetic material, and means on opposite sides of the frame serving as guides for the cutter chain, at least part of said guide means being in a normally horizontal plane which passes through the rotor. The machine may be of shortwall, longwall, shortwall-longwall, arcwall or other type. General arrangement.-A shortwall machine comprises a motor frame 41 and a gearing frame 42 bolted together, cuttings-removing means 43 removably attached to the rear of the gearing frame, a cutter-chain jib 45 extending forwardly from the motor frame, and rope drums 48, 49 with a uni-directional drive for feeding the machine. Cutter-chain drive.-Hollow motor shaft 59, Fig. 3, acts through pinions 61, 62, bevel gears 64, 65, and dog clutch 84 to drive a shaft 69 carrying cutter-chain sprocket 70. Clutch 84 is controlled through shipper 85, and a crank 87, Fig. 9, connected by link 88 to a crank 89 on a transverse shaft 90, a handle 91, Fig. 1, being provided on each end of the latter. Removing cuttings.-A bevel gear 82, Fig. 3, fixed to bevel gear 65 acts through bevel gear 92, shaft 93, cup 94, pins 96, and reversing bevel gearing 100, 101, 102, Figs. 3 and 6, to drive a transverse shaft 105 connected at each end through bevel gearing 128, 129, to vertical shafts 130 carrying cylinders 132 with slots 137, Fig. 17, through which project blades 135 rotatable on an eccentric post 134. Guides 138 on the frame 43 steer cuttings from the cutter chain to the removing means and have slots receiving pins 140 on the gearing frame 42 to assist in positioning the posts. The reversing bevel gearing is controlled through a dog clutch 107 with bevelled teeth allowing yield under overload ; the clutch is moved by a pivoted shipper 108 connected to a rod 120 held between centering springs 123 in a frame 121 secured to a rod 122 movable axially by a pivoted lever 124, Fig. 1, held in adjusted position by ball &c. detents, a further ball detent 110, 111, Fig. 3, being provided for the neutral position of the shipper. Interlocking means-see belowbetween lever 124 and the motor reversing switch ensure correct rotation of the cuttins-removing means in spite of reversal of the direction of cutting. Truck-drive.-A bevel gear 112, Fig. 3, driven from the bevel reversing gear 100 ... 102, is connected to a power take-off 115 from which a transport truck for the machine may be driven; when the cuttings-removing means is detached, the truck may be driven from the cup 94. Motor and motor details ; cutter-chain support.-The armature is mounted on a hollow shaft 156, Fig. 4, the hollow drive shaft 59 passing through the shaft 156 and being connected to the forward end thereof through an overload release clutch comprising plates 176 alternately connected to driving and driven members 172, 173, secured respectively to the shafts 156 and 59, springs 174 applying pressure to the plates. The rear end of shaft 156 is supported in a bearing block 158, Figs. 4 and 31, sliding into a cup 159 on the motor frame 41 ; around the block 158 are spaced notches 163, Fig. 31, any of which is engaged by a spring-pressed pin 164 to hold the block against rotation. An air-circulating fan 170, Fig. 4, is secured to shaft 156. The cutter jib 45 has a rearward extension comprising spaced arms 189, Figs. 2, 4 and 7, forming skids, the forked rear ends 190, Fig. 4, of the arms slidably engaging pivoted bearing blocks 191 ; the jib 45 is normally held rigidly by screws 195, Fig. 7, threaded to the machine frame, but on removal of the screws and raising of the front end of the machine by jacks 58, the armature and parts secured thereto may be removed through the forward end of the machine. The motor frame has side grooves 207 forming rear guides for the cutter chain. The direct current motor shown comprises side pole shoes 198 with field coils 199, top and bottom pole shoes 196, 197, and interpoles 202 with a compensating coil 204, the shoes being removably held by bolts. An alternating current motor, preferably of induction type, may be substituted. Feeding the machine.-The bevel gear 82, Fig. 3, drives opposed bevel gears 210, Fig. 9, one or other of which drives a sectional transverse shaft 227 through gears 217, 218, and a one-way clutch 219 comprising an outer driving member 223, Fig. 18, an inner driven member 226, and intermediate spring-pressed clutch rollers 228. Each end of the shaft 227 is adapted to drive the adjacent rope drum 48 or 49 through a hydraulic coupling 234-see below-gears 255, 262, 263, 260, two-speed planetary transmission 261 including high and low speed brake bands 268, 269, applied respectively by hydraulic piston motors 278, 272, pinion 280, and internal gear 282, the latter being engageable with the respective drum by a clutch comprising a spider 291, Fig. 15, movable by a spring 296 to cause pins 292 thereon to engage openings 293 in the internal gear 282 ; the clutch is releasable hydraulically by a piston 299 bearing on the spider, actuating fluid being supplied automatically through a slide valve actuated when the hydraulic coupling is adjusted to zero torque position. Fluid supply to motors 278, 272, is controlled by axial movement of a shaft 338, Fig. 20, carrying a valve 348. The drum also carries spring-pressed pins 301, Fig. 16, bearing frictionally on the internal gear 282 whereby when the clutch is disengaged, the feed rope can be pulled off the drum under drag. Feed rope guides.-At the rear corners of the machine are pulleys 52, 53, Figs. 1, 2 and 6, each mounted on a stub shaft 150, Fig. 6a, on an arm 149 protruding from a member 147 pivoted in upper and lower brackets 145, 146 ; a slot 147a in member 147 may be moved into register with a slot in bracket 145 to permit removal of the feed rope. At the front corners are pulleys 54, 55, each carried on a stub shaft 186, Fig. 7, on a pivoted bracket 185 which, when the pulley is not in use, is held in raised position by a latch 188. Hydraulic coupling 234 comprises a body 235, Fig. 10, fixed to the driving shaft 227 and having cylinders 236 each containing a piston 237 urged outwardly by a spring 238 and carrying a roller 239 engaging a cam 240 removably held between parts 241, 242, Fig. 9, of a housing secured to the driven gear 255. The coupling is immersed in an oil bath 212 from which oil passes through screened openings into the housing and thence, when the pistons 237 move outwardly, into the cylinders 236 through ports 247 in the pistons, ports. 247 being controlled by spring-pressed check valves 248. The cylinders 236 also communicate through check valves 249 and passages 250 with a central port 251 in the body 235 to which oil is supplied at variable pressure to control slip of the coupling. Slip control means 313, 314, Fig. 1, are provided at each side of the rear of the machine and each comprises a balanced pressure-relief valve consisting of a spring 319, Figs. 20, 21, 23, between a piston 320 and a flanged sleeve 321, the latter having limited movement before contacting the spring ; a piston 326, open to the oil pressure through inlet 327 and ports 330, acts on the sleeve 321 through an inner flanged sleeve 323, while the piston 320 acts through a lever 336 on a valve 332, excess pressure opening valve 332 and allowing some oil to escape. To vary the slip of the coupling, sleeve 321 is adjusted by rotation of a shaft 338 acting through bevel gears 342, 343 and a pinion 344 engaging a rack on the sleeve ; a spring- pressed ball engages pinion 344 to assist in holding the sleeve in adjusted position. Raising or tilting the machine.-Two hydraulic jacks 57, 58, Fig. 2, are provided on each side of the machine, jacks 57 being connected in parallel for common control and each jack 58 being separately controlled, control being effected from either side of the machine by two sets of three valves ; each valve comprises a spool 370, Fig. 20, normally held in the jack-locking position shown by a spring 382, but movable in either direction to connect a chamber 379, leading to the jack, with a fluid supply chamber 378 or with an exhaust chamber 380. Dual controls.-The shaft 338 of each control box 313, 314, carries a pinion 387, Figs. 20, 26, 29, with a gap co-operating with a lug 388, whereby the shaft 338 may be moved axially to vary the planetary transmission only when the hydraulic coupling is at zero torque position. Shaft 338 of control box 313 may be operated from the opposite side of the machine from handle 401, rotation being conveyed through gearing 399, 398, 396, 395, hollow shaft 393 and gearing 392, 391, while axial movement is conveyed to hollow shaft 393 through shrouds on gears 395, 399, engaging gears 396, 398 which are fixed to a slidable shaft 397 ; shaft 393 acts through rocker arm 403 to slide the shaft 338. Shaft 338 of control box 314 may be similarly operated from handle 405 on the opposite side of the machine through gear 408 or rocker arm 412. Motor control interlocking gear.-The motor switch 419, Figs. 33 and 34, is operable through cam 420 by handle 421, or from the opposite side of the machine through cross rod 423 and linkage 424, while the motor-reversing drum 416 is operable by handle 418 or from the opposite side of the machine through cross rod 433, slotted member 432, and arm 430 ; a guided latch pin 426 is reciprocable by an arm 425 on the switch and co-operates with a cam 429 on the reversing drum to prevent reversal of the latter except when the switch is open. On reversal of the drum, a roller 436 acts through arms 435, 437, to move a transverse rod 438 with notches 441, 443, Fig. 2a, co-operating with a U-shaped yoke 442 on a slidable rod 44