US2905441A - Hydraulic powered mining machine - Google Patents

Description

Sept. 22, 1959 w. N. PoUNljsToNE v 2,905,441

HYDRAULIC POWERED MINING MACHINE Filed Feb. 5, 1954 5 Sheets-Sheet 1 Sept. 22, 1959 w. N. PouNDsToNE 2,905,441

HYDRAULIC POWERED MINING MACHINE Filed Feb. 5, 1954 5 Sheets-Sheet 2 Sept. 22, 1959 w. N. PouNDsToNE HYDRAULIC POWERED MINING MACHINE 5 'sheets-sheet s Filed Feb. 5,4 1954 ATTORNEY a E 7 \5 N w R 6 2 M.. mw-a w 2 6 nlc. 4 w u O M N frm 0 3 M 3 3 3 3 3 M M 3 M 3 3 M M D 3 f f M W u W l -le I .,l v. om w. 3 4s 4 am I na .w M .M nu M 3 3 3 M mn i s .a i n 6 n 5 o @n N 3 vn f Y G. Nm H D E 5mm wm im foon oN www Nm `0 OJV `N m @E www. y

Sept. 22, 1959 w. N. PoUNDsToNE v2,905,441

HYDRAULIC POWERED MINING MACHINE Filed Feb. 5, 1954 5 Sheets-Sheet 4 ATTORNEY W. N. POUNDSTONE HYDRAULIC POWERED MINING MACHINE Sept. 22; 1959 5 Sheets-Sheet 5 Filed Feb. 5, 1954 aNvx-:NToR WILLIAM N. PouNDsToNE BY ATTORNEY HYDRAULIC POWERED MINING MACHlNE William N. Poundstone, Morgantown, W. Va., assignor to Consolidation Coal Company, a corporation of Penn- Sylvania Application February 5, 1954, Serial No. 408,371

4 Claims. (Cl. Z55-47) The present invention relates to improvements in hydraulically powered mobile mining machines and particularly to rotary drilling machines.

In underground mobile hydraulic drilling machines, the auger has two separable working motions, each of which has an independently controlled hydraulic power source. The rotational motion of the auger is powered by a hydraulic rotating motor having a rotational velocity, which can be modified by regulating the rate at which hydraulic fluid passes through the hydraulic motor. The longitudinal motion of the auger is controlled by a hydraulic ram which advances the auger in accordance with the rate at which hydraulic uid is introduced into the hydraulic liuid chamber behind the ram piston. The operator of these drilling machines must be skilled in controlling the independent valves in the hydraulic feed lines to the motor and the ram so that the auger attains a rapid drilling rate without advancing the auger so rapidly that the auger rotation motor stalls.

According to the present invention the hydraulic circuit for the rotational motor is hydraulically correlated with the hydraulic circuit for the advancing ram whereby the advance is regulated automatically by the capacity of the rotational motor. The advance is maintained at the highest rate consistent with the capacity of the rotational motor. Thus the drilling machine automatically is operated at a torque near the maximum possible torque, while the possibility of stalling is eliminated. Hence holes can be drilled with highest eiiiciency. Moreover the operator of the machine need not be as experienced as the operators required for prior drilling machines.

The principle of my new invention can be applied to other mobile mining machines which combine a rotational motion with a longitudinal advance motion in the working elements, such as roof bolting machines, cutting machines and continuous mining machines.

The primary object of this invention is to provide automatic means for exerting the maximum longitudinal advancing force consistent with the maximum rotational force which a mining machine is capable of developing. Another object of this invention is to permit operation of drilling machines by relatively inexperienced operators by providing a single manual control valve together with an automatic valve means for integrating the two mechanical motions of rotation and longitudinal advance.

A further object of this invention is to provide a drilling machine which cannot be stalled in normal operation.

Another object of this invention is to provide a drilling machine in which the auger is automatically safenited States Patent fice guarded from excessive stresses, even those which develop unexpectedly when the working auger bit encounters an area of unusually hard material in the path of the drill hole.

Another object is to reduce abrasion of cutting tools by automatically avoiding free rotation of the cutting tool under abrasive conditions.

Other objects and advantages of the present invention will become apparent from the following specification and drawings. It is to be understood that modifications from the exact structural details are contemplated within the scope of the appended claims without departing from the spirit of the invention.

In the drawings:

Figure 1 is a schematic illustration of the preferred embodiment of the present invention;

Figure 2 is a diagrammatic illustration of the valve means Shown in the drilling machine embodiment of Figure l;

Figures 3, 5 and 7 are schematic illustrations of hydraulically powered drilling machines, each of which embodies other modifications of the control system of the present invention;

Figure 4 is a diagrammatic illustration of the valve means shown in the drilling machine embodiment of Figure 3;

Figure 6 is a diagrammatic illustration of the valve means shown in the drilling machine embodiment of Figure 5; Y

Figure 8 is a diagrammatic illustration of the valve means shown in the drilling machine embodiment of Figure 7; and

Figure 9 is a diagrammatic illustration of a hydraulically powered continuous mining machine employing the control system of the present invention.

Throughout the drawings, like numbers are employed to indicate corresponding elements of the drilling machine.

The prior art Rotary hydraulic drilling machines as used in underground mining operations comprise a transportable frame upon which is mounted supporting structure for a drilling auger. The auger is caused to rotate by means of a primary hydraulic motor which may be of the piston, vane, gear or rotor type. The auger is caused to move longitudinally by secondary hydraulic means, for example, a hydraulic ram having a cylinder and piston. Other suitable hydraulic advance devices include a secondary hydraulic motor having a chain and sprocket drive or a rope and shive drive or a rack and pinion drive. Longitudinal movement of the auger effects both ad- Vancement into a drill hole and retraction from the drilled hole. Each of the two principal hydraulic circuits has an independent control for the ow of hydraulic fluid.

In the present invention the two principal hydraulic circuits are coordinated through a direct hydraulic connection whereby the resistance to rotation encountered by the auger determines the rate of advance of the auger. In various modifications of the present invention, the flow of hydraulic fluid to the advancing circuit is throttled, short-circuited or divided in response to the uid pressure in the rotating motor circuit. The pressure of the hydraulic iiuid in the feed conduit leading to the primary rotating motor increases when the resistance encountered by the auger increases; hence by reducing the flow of hydraulic: fluid to the secondary advancing circuit when high pressures are developed in the primary rotating motor feed conduit, the rate of advance of the auger is automatically reduced below normal speed under conditions of high drilling resistance.

Preferred embodiment A The preferred embodiment of the .present invention is shown in Figure lwhich is a schematic illustration of' the essential features of existing hydraulic drilling niachines. Throughout the drawings, corresponding" nurnerals are used to indicate corresponding elements. In the drilling machine shown in Figure l, an auger 10,Y tipped with a cutting bit (not shown), is caused to rotate by means of a primary hydraulic motor 12 is mechanically associated with the auger shaft in any convenient manner such as gearing, chains, belts, direct drive, and the like. The motor 12 is powered by hydraulic fluid from acontinuously operating ,pump 14 which receives iluid from a reservoir 1 8 through conduit 16 and delivers pressurized 'fluid through conduit 20 to the motor 12. Low .pressure huid' is returned from the rntor 12 through conduit '22 to die dreservii 18. Joining conduits 20 and 2'2 is a safety relief conduit 2.4 having a relief valve 26 adapted vto open `vvhen predetermined excessive pressures develop in the fluid conduit 20. A by-pass conduit 28 having a manuallyoperated valve 30 is provided between the conduits 2 0V and 22. With the valve 3'0 closed, the pump 1* 4 sends hy daulic Huid under' pressure to vthe mt'oi" 12`ft e leet rotational motion. With the valve 30 open, 'the fluid from lilli pu'rrip I4 passes 'through the conduit 28 and Vle'tllrns direotly "t the reservoir 18 for recirculation. Thus the valve 30 in effect is an on-ol control for the rotatihal ntion of the motor 12.

Advirhrit and refraefin f the Y'ilgei" is eted (in this illustration) by ahydraulic ram comprising a. ylilidr 32 having a closely ttig, eCpcbleV 4piston 34 ehneeted vvith e shaft 36 vvhl'ch 'determines the 'pesition of the auger with respect to the supporting 'strucf. III Sl'ne drilling mhirls the "sh'ft 36 iS joined "the Supporting Structure Whil th 'Cylinder 32 'is mechanically 'associated vvitlj the auger; in other machines fthe itig/lieder is hixed te the supporting 'structure vvhile th' pistn iS 'associated 'vv'itli the l'ge. The" hydruli ram is powered by hydraulic iluid from pump 48 which receives iluid through 'conduit 50' from the reservoir 1S and delivers uid under .pressure through conduit vS2 and appropriate valving to the Ihydraulic ram. Atwoposition, lfour-port reversing v alve 40 is shown for illus- -frative purposes. Hydraulic' uid under pressure in conduit 52 passes through the valve 40 as shown `in Figure 1 and enters the cylinder chamber 3S throughwconduit 42, causing the piston 34 to move to the right. 'The hydraulie 'duid inthe cylinder chamber i4 behind-the :piston returns to the reservoir 18 through conduit 45, valve 40 and conduit 54. As in the rotating motor circuit, a "safety relief conduit 56 with a relief valve V5S is provided to eliminate excessive pressures in the conduit 52; Also as in the motor circuit a by-pass conduit 60 Vhaving `a manually operated valve 62 is provided between the conduits 52 and 54 for short-circuiting the hydraulic fluid Yfrom the pump 48 away from the cylinder 32. The valve 62 affords manual on-oil control of the Hydraulic'a'dvanee rnean's.

'n its alternate -positill the vlv 40 joins dit '52 with conduit 46 for feeding Hydraulic uid iri't' 'Chamber 44 tO retract the glj S'illlltn'buly the valve 40 loins conduit ft2 'with conduit '54 for returning 'hydraulic fluid from the chamber 318 to the reservoir I8 during auger retraction.

With both pumps 14 and 48 operating continuously, and the valves 30 vand 62 'in an op position, there i's neither rotation nor longitudinal niovnie'nt in the auger. Having its auger' in'a'ret'aeted position, 'the drilligniachine is moved to a selected drill hole site and the auger 10 is aligned for drilling. The valve 30 is closed to commence rotation of the motor 12 and the auger 10. The valve 62 is closed to cause the drill to advance into the working face for drilling the hole. The maximum rate of advance of the auger 10 is determined by the capacity of the pump 4S. Throughout the drilling operation, when the machine operator observes signs of increased drilling resistance, he instantly opens the valve 62 to prevent stalling of the rotational motor 12 through excessive loads on the drill hitl. lf the operator successfully opens the valve 6 2 at theinstant drilling difcuties are encountered, the advance of the auger is stopped and the auger rotation 'Without the advance pressure permits the 'uge t?) 'drill itself fle. Th'iou'pil, tb vid unnecessary and nonproductive free rotation, the operator must immediately sense the removal of the ditliculty and close the valve 62 to permit the auger to advance once more at its normal speed. Where lthe area of high drilling resistance extends through a considerable distance, the operator must repeatedly open and close the valve 62 in order that the advance of the auger does not exceed the cutting capacity of the drill bit. These intervals of free rotation of the auger are no't only nonproductive machine time, but also are destructive to the Vauger Bits which are subjected to serious abrasive conditions when freely rotating rather than cutting; hence the auger bits have a shortened useful life and must be replaced with undue frequency, Nevertheless,` without the required free rotation, auger bits may be broken through excessive stresses, or the Yprimary hydraulic rotating motors may be stalled.

In the preferred embodiment of the present invention a by-pass 'conduit v1'02having a valve '100 is provided between the hydraulic cylinder feed conduit 52 andthe cylinder return conduit S4. The valve is biased in a normal position in which hydraulic uid can-,pass therethrough only if the vpressure in conduit 52 exceeds the predetermined bias of the valve. A pressure tap conduit joins the .primary hydraulic circuit feed conduit 2'0 with the operating piston chamber of the val-ve 100.

The valve 100, shown in greater detail in Figure 2, comprises a cylinder 112,- 'a laterl .port 108, an internal bore 114 and threaded axial ports "116 and I11S. Extending into the cylinder is e sleeve 'having internal threads 122 and external threads 124 at' ehe end. 'The external threals124 engage the internal' threads 1.18 `ef 'the `cylinder 112. The iiltnal threads 122 engage the external threads 126 of a valve seat insert 128 having a bore 104'v`vhich joins with conduit 102, A cup-piston 1.30, having an internal here 132 vvhi'eh terms a surface s'lidably engaging the outside Wall of the sleeve 120, has an external srfae which 'slidably 'engages the bore 114 or the valve cylinder 112. A 'pert- 3'1 extends through the head of the piston 130. Grooves' 1321 'are provided in 'the sleeve` 12()V for" receiving sealing rings to effect "e Atight seal between the piston here 132 and the sleeve 120. similarly gree've's 136 are provided th the pistn to receive sealing rings te effect Va tight seal between the piston and the here 1'14 eff the cylinder 112. A reducing nipple 138 is provided vv'ith externalthr'eads 140 vtij 'l'gge th internal threads 116 Of tli yiidei 112. Ah axial here 142 rhhs through the nipple 13'8. Threads 144 l'are 'prvided iii-ille pO't 10616 engage the conduit 102. A ep'rihg 146 is .psijtiehed ih the 'chamber 148' 'termed hv theylihd'er' 'here 114, the nipple 138 'and the piston 130. The cmpres'sloh ofthe spring 146' is adjusted' hy turning the nipple 138. A 'second spring 150 is npesitioned in the chamber 152 within the sleeve 120; A bll 154, having 'a diameter greater 'than the here ofthe' valve seat insert 128, rests irl-a valveseat 129 'tif the v'insert 1128'. A cap member 156 conforms to the shape of the"b`ll 154 and engages the bali The spring 151i is' cehipressed 'between the piston 130 and 'the capahehiber 156. "the compression of the spring 150 is adjusted by threading the valve seat insert 128".

The piston 130, therefore, is maintained in a normal position which is determined by the relative compression of the springs 146 and 150. The downward movement of the piston 130 is limited, of course, by the upper lip of the sleeve 120, and, as shown in Figure 2, the piston is in its lowest possible position. An annular chamber 158 is formed by the bore 114 of the cylinder, the external surface of the sleeve 120, the bottom of the piston 130, and the bottom closure of cylinder 112. The chamber 15S communicates through theport 108 with the conduit 110 which transfers the pressure of the primary rotational motor feed oil conduit.

The valve 100, when installed in a drilling machine, acts as a pressure relief valve for venting excess hydraulic pressures from the feed conduit 52. The valve 100 is biased to permit the ow of hydraulic Huid past the ball 154 when there is no hydraulic pressure in the primary feed conduit 20, to limit the maximum pressure which can develop in the conduit 52, and hence to limit the' maximum advance force which can be developed within the hydraulic ram 32. Thus, when the primary rotational hydraulic motor is encountering little or no resistance, the pressure transmitted through the conduit 110 from the primary motor feed conduit 20 is insuicient to overcome the resistance of the biasing spring 146, and the valve 100 acts merely as a pressure relief valve for the conduit 52.

The vented hydraulic fluid from conduit 52 passes the ball 154 into the chamber 152, through the port 131, into the chamber 148, through the bore 142, the port 106 and into the conduit 102 whence it is returned by conduit 54 to the oil reservoir 18. This normal pressure setting is determined by the compression of spring 150 when the piston 130 is in the position shown in Figure 2.

When the pressure in the conduit 20 exceeds a predetermined maximum value, the transmitted pressure through conduit 110 moves the cup piston 130 against the biasing spring 146, thereby reducing the compression in the valve spring 150. With less compressive force acting against the ball 154, the relief setting of the lvalve '100 is reduced so that under these conditions the maximum pressure which can be developed in the conduit 52 is less than `that when there is no load on the primary rotating motor.

Should the auger resistance return to a low value, the pressure in the conduit 20 is again reduced and the biasing spring 146 again restores the cup piston 130 to a position in which the compression of the spring 150 is increased toward its maximum value.

Under usual operating conditions, the hydraulic pump 48, which supplies hydraulic fluid to the auger advance circuit, will have suicient capacity to provide hydraulic fluid at a rate corresponding to the maximum design rate of advance and under sufficient pressure to provide the maximum design advance force upon the auger. Thus, under usual operating conditions, some hydraulic fluid will be passing through the valve 100 from the conduit 52 at all times.

The present modification, of course, is not limited by the mechanical features of the valve described and illustrated in Figures l and 2. Any hydraulic pressure relief valve which has a relief setting adapted to respond inversely to a secondary hydraulic pressure may be employed in the by-pass conduit.

One of the outstanding advantages of this modification of the present invention is that the hydraulic fluid in the cylinder 32 can return through the valve 100 to relieve the pressure acting against the piston 34 when the auger is under heavy stresses.

Additional advantages of the present invention can be described now that its operation is understood. In addition to providing automatic control of the rate of ad- Vance in response to drilling resistance, the present nvention provides an automatic control over the rate of advance as limited by clogging of the drilled material in the ights of the auger shaft.

When drill bits become dulled through use, their cutting capacity is reduced. Since prior machines were controlled manually, the operator had no way of knowing when drill bits had become dulled; by continuing to use the drilling machine at the normal rate when the bits had become dulled, the operator placed undue loads upon the machine, usually stalling the hydraulic motors. With the present invention, however, the problem of dulled bits is eliminated. The load on the machine is maintained automatically at the design torque regardless of whether the bits are sharp or dull. With dulled bits, the rate of auger advance is automatically reduced. When the operator observes that the drilling operation is carried out at a substantially reduced rate, he has an indication that the drill bits have become dulled and should be replaced. This also eliminates the practice of replacing bits periodically without regard to their condition. With the present invention, the operator knows when the bits are dull and needs to replace them only when the drilling rate of the machine is reduced thereby.

Modification of Figure 3 The embodiment of the present invention shown in Figure 3 provides a valve 200 in the hydraulic cylinder feed conduit 52 for throttling the llow of Huid in response to the pressure existing in the rotating motor feed conduit 20. The valve 200 is of the spring loaded piston type (for illustration) and, as shown in Figure 4, cornprises a cylinder 202, a bore 204 and a threaded axial pressure port 206 at one end and a threaded axial valve seat opening 208 at the other end. A lateral port 210 is provided to receive hydraulic oil being pumped from the oil pump 48. A plunger 212, having a piston end 214, a shaft 216 and a valve head 218, is slidably positioned in the bore 204. Grooves 220 are provided in the piston Wall for receiving sealing rings 222 which are preferably O rings or similar sealing material to effect a tight seal between the piston walls and the cylinder bore. A valve seat insert 224 having external threading 226 which engages the valve port threading 208, has an internal bore 228 with a valve seat 230 corresponding to the valve head 218. A spring 232 is positioned in the annular space between the shaft 216 and the cylinder bore 204. The spring is seated against the valve seat insert 224 and the piston 214. By proper threading adjustment of the valve seat insert 224, the compression of the spring 232 against the piston 214 can be maintained at a desired predetermined value. A conduit 236, communicating with the feed oil conduit 20 of the rotational motor circuit, communicates at the threaded axial pressure port 206 with a chamber 23S within the valve cylinder behind the piston 214. Conduit 52, carrying pumped oil from the hydraulic ram pump 48, communicates at the port 210 with the annular chamber formed within the valve between the bore 204 and the shaft 216. Conduit 52', carrying pumped oil to the hydraulic ram, communicates with one port of the four-way valve 40 and also with the bore 228 of the valve seat insert 224.

With hydraulic uid in the rotational circuit owing through the conduit 20, the pressure within the conduit 20 is transmitted through conduit 236 against the head of the piston 214. The compression of the spring 232 opposes the hydraulic pressure against the piston and biases the valve seat 218 in a normal position out of contact with the valve seat receiver 224. Oil owing to the hydraulic ram 32, passes through conduit 52, port 210, the annular space between the valve cylinder bore 204 and the shaft 212, through the bore 228 and the conduit 52 to the reversing valve 40. Hydraulic ram fluid will continue to ow through the valve 200 until the pressure in conduit 20 exceeds the normal pressure which` i balances the 'conter-essieu of the spring 232. 'with pressure's inthe conduit zo exceeding nor'inal,jtlret pistou 214 is forced against the spring 232, reducing the area or now available to Vthe hydraulic ram fluid, thereby 'throttling the new o'f hydraulic r'a'rh oil. With 'even higher 'piessurejs developing lin conduit 20, the valve head 'als will be toiced into contact with the valve seat 230 tocut en mplet'ely the iowof 'oil 'through the valve 200 to the hydraulic r'rain '32. when theprotating auger V10 has been freed ofthe resistance `jvvhich increased its stressjthe pressure in 'conduit '20 will be restored to normal and the spring v232 will fr'c'e the piston 214 back 'against' .the reduced pressure, thereby 'restoring' the full normal flow area to the hydraulic ranihuid within the valve 20,0.

method of controlillustr'ate'd in the modication of Figure v'3is 'not limited to the mechanical features/of the valve 200. I Any normally open hydraulic duid" valve may be used if 'adapted to reduce the flow orifice iii ijes'porise to increased pressures from a hydraulic fluid circuit.

Modification of Figure A third einhodinient of the present invention is yillust'rated and described in connection with Figures 5 "and v6. A valve, generally indicated by numeral 300, is provided in theconduit 52. The vvalve 300 is of the sliding spool type', vhaving a spool 302 slid'ably fitted within a valve easing 304. The spool 302 comprises two piston ends 306 andf308 having grooves 310 and 312 for receiving sealing il'gs yto provide a tight seal betwen fhep'valve pistons and the bo're 314y of thevalve casing 304. A shaft 316, having a diameter less than that 'ofuthe valve c'asi'lg bore -3014, join's the two valve pistons306 and 308 to :provide 'a 4chamber 318 for hydraulic fluid. Three ports are provided through the valve casing 304; thc' port 320 joins the conduit 5'2 with the chamber 318; the'p'o'r't 322 joins the chamber 318 with the conduit 52'; and the po'rt3`24 joins lthe chamber 31s with Aa hydraulic by-Ypass conduit 3'2`6 which communicates with the hydraulic fluid returiico'nduit 54. Another valve chamber 328 is p'rovided bet'vveel'n the head of valvepistorn 30S, the casing bore 314 and a threaded plug 330, adapted to `s'c'al the ed of "the valve casing bore 314. A port332v is pro; v'ded 'in the plug 330 to provide communication between the chamber' 328 and a conduit 334l communicating with the rotating motorfeed line 20. At the opposite end of the' valve casing 304, a second threaded plug 336v is provided to seal the valve casing bore 314. A third valve chamber 338 is formedby the head of thevalve pisto'i 306, the casing bore 314 and the plug-336. A port 340 in the 'plug 336 joins the chamber 338 with conduit 342 communicating' with the hydraulic uid return' 'coi'iduit 54. A spring 344 is provided lin the climb'e'r 3538` under compression between the plug 33'6 and 'theV head of `the valve jpiston 306. In normal posi# tion, the spring' '3 44 urges the spool 502 awa-y freni the plug 336 so that the port 324 is sealed from the chamber 31s by the valve piston 306, whereasthe piston 30s is ont or engagement with the port 322 whereby open communication between 'ports through the annular chamber 31s. I Y A When the valve means 300 -'s installed in a drilling in'cliine under normal operating conditions, hydraulic iiuid flows from the `pump 43 through 'conduit 52, port 320, chamber y318, vport 322 and conduit S2" to 'operate the hydraulic ram 32. However when the auger bit encounters resistance, the back 'pressure in the hydraulic feed conduit is transmitted through conduit 334 and port '332 to the chamber e728 whc'rc it acts against the head or the valve piston sus, causing `the spool to ad- Vance against the spring 344. The movement o'f the spool "302' lopens' the port 324 and partially closes the port 322 whereby the flow of hydraulic duid in conduit '$2' is 'throttlcdbctwcen thcd'hydrajulic rain conduit l512 and' the hyrpa'ss conduit 526. 'when' the lresistance to 32e and 322 is provided f rdtti the 'rdtice'd pressure in the chamber 323 is overcome lby the compression fr'ce of 'the 344 "tlv've 302 returns to normal'poeition, Ted-toting the normal rat 'f auger fadvane in the hydraulic As' an additional feature, a narrow neck 34o nray 'be provided in 'the inner wall of vthe valve 'c 'a's'ng to @limit 'lie' 4'sliding range f the valve spool 302. When narrow jne'c'it "is provided, one of the pistons rnay be tlrjreaded -erifo the sha-:ft 31e as indicated by the threads' 343i. niit 3`49f1`y be used `to lock the piston to .the shaft. f '-Ihe el-ug 336 is provided vvith external 'thrm'ds 350 engage 'threads 352 in the valve casing to' 'ses cure the oonnecii 'and permit 'adjustiilent of the com# pression 'of the 'spring 344. Excess hydraulic oil in the haibr 33% vfd `through the `port 340 and conduit 342 te avoid hydraulic resistance 'to the free rnovenient of the spool 362.

A- fourthv embodiment of the present invention lis ilf -lustlated and described in connection with Figures Tand 8. Valve means indicated .generally by the numeral 400 are provided -in 'the :hydraulic conduit 52. The valve means 400 comprises a cylindrical valve casing 402 havh ing ffour different bores,- 404, 406, 408, Yand 410. A valve piston sindicated generally by numeral 412 is provided with a spring engaging head 414 Yhaving a diameter less `than the valve bore 404. A'shank portion 416 of the valve ipiston 412; adapted to engage the `valve bore 406, is provided with-,grooves v41S for receiving scaling rings to provide -a tight seal` between the shank 416 and the bore 406.` -A fshaft 42.0, adapted to engage the bore 408,- also is .provided with grooves 422 for receiving sealf ing rings to provide -atightscal between the shaft 420 and the bore 408. A valve head 424 is provided at-the end' of lthe shaftA 420 to engage a valve seat 42S which is axial-ly positioned in a valve seat insert 426, threaded into the valve casing.V A chamber 428 is formed in the valve casing between the bore 410 and the shaft 420. Gommunicating with the chamber 428 are three valve ports: the' port 430 vjoins conduit 52 with the chamber 428; the port 432 -joins the chamber 428 with 'the conduit 52; the lp'ort 434 joins the chamber 428 with -a conduit 436 communicating with 4.the hydraulic fluid return conduit S4.

Anannular chambe1'438 is formed between the valve bore 406 and the shaft 420. One Vport 440 joins the chamber Y438 with 'the conduit 442 vcommunicating with the' feed conduit 20 'of lthe rotational mo'tor 12. A chamber 444 is formed `by the valve bore V404, the piston head 4114 and a 'threaded ,plug 446 which is secured in the' casing by threads; 448. A `spring 450 `is provided in `thel chamber 4441under compression between the' plug 446 Aand the Ypiston head 414. YIn 4normal position,I the piston, as shown in Figure 8, is urged towards the annu= lar lip at' the bottom of the ychamber 444 by the com pressive force of the spr-ing 450, whereby 4the valve -hoad 424 vengages vthe valve seat '425 to seal vthe port 434'. Under normal condi-tions, hydraulic duid from the p'ump 48 passes' through the `conduit 52 and the port 432 into the annular-chamber 428, through the port 430 into the conduit 52 to operate `the hydraulic r'am 32.

lWhen the auger -10 encounters increased resistance, the pressure in the' hydraulic fluid feed conduit 20 is transmitted through lthe conduit 442 and the` va'lve port 440 irl-tdV the annular chamber 438' where -it acts against tl'lepshank 416 t urge `the valve piston 412 upwardly against the' biasing 'spring 450.

Whe! Vlv jt fd V'lllJvVE-l'rtlly, the valve head 424 is disengaged from the valve seat '425 to open the v'lve port 434 and permit the hydraulic iluid "fiom the fciiduit- 52' to 'be Idivided between the' conduits 436 a'rld 152% VrSin'c'e 2there eubs'taitially Eno resistance Ft the how of liuid through the conduit 436, the bulk of the hydraulic fluid will by-pass the hydraulic ram circuit` When the resistance to rotation is diminished, the pressure in conduit 7.0 is reduced together with the pressure acting in the chamber 438; the compressive force of the spring 456 once more forces the valve piston to its normal position, wherein the port 434 is closed and the fluid in conduit 52 passes to the hydraulic ram circu-it once more.

The compressive force of `the spring 450 can be adjusted by a threaded adjustment of the nipple 446. A port I452 is provided Iin the nipple 446 to permit hydraulic oil to leave the chamber 444 through conduit 454 which communicates with the hydraulic iiuid return conduit 54. The engagement of the valve head 424 with the valve seat 425 can be adjusted by the threaded connection between the insert 426 and the valve casing.

This modification of the present invention has the added advantage that the conduit between the hydraulic pump 48 and the hydraulic ram is at all times unobstructed. Hence, even when the by-pass conduit 436 is opened yas the result of increased pressures in the rotation motor circuit, the passage between the valve 400 and the hydraulic ram is opened so that undesirable liquid pressures in the hydraulic ram can be relieved through the conduit 436.

When hydraulic drilling apparatus lhas its hydraulic circuits integrated in vaccordance with the present invention, the auger automatically operates at its maximum torque. The auger is advanced at the maximum rate consistent with the cutting load encountered by the bit. Guesswork on the part of the machine operator is eliminated; stalling of the hydraulic liuid motors is avoided; excessive stresses are prevented from developing in the system. The machine can be used without regard to the drilling load to be encountered since the machine itself responds instantly to variations in cutting resistance.

The machine is responsive to increased resistance whether resulting from encountering a hard, dense materal or from the clogging of the auger flights with drilled material. Furthermore the machine automatically adjusts its drilling operation according to the sharpness and ability to cut olf the drill bits.

When converting existing drilling machines in accordance with the present invention, care should be exercised that the hydraulic fluid supply reservoir is sufli- -ciently large to prevent overheating of the fluid through the high pressure drop encountered by the fluid in the rapidly moving automatic control valves.

In adapting the present invention to existing mining machines, the particular valve selected as the control device may respond too rapidly to momentary changes in drilling resistance with the result that the drill advances in sporadic movements which can harm the equipment. To prevent too rapid fluctuations of the rate of auger advance, dampening devices may be inserted in the hydraulic conduit which transfers the pressure from the primary hydraulic circuit to the control valve in the secondary hydraulic circuit. Typical dampening apparatus is illustrated in the transfer conduit of Figure l. A restricted orilice 170 is installed in the main pressure tap conduit 110. A by-pass conduit 172 having a checkvalve 174 is installed in parallel relation to the restricted orifice 170. The check valve 174 permits hydraulic tluid to move through the conduit 172 only from the primary hydraulic circuit toward the valve 100. The restricted orice 170 permits hydraulic iiuid to ow freely in either direction, but at a slow rate.

^ Thus, when the pressure in the primary hydraulic circuit increases, hydraulic iiuid can flow instantaneously throughfthe by-pass conduit 172 and the check valve 174 as well as through the restricted oriiice 170, to operate the valve 100. When the pressure in the primary hydraulic circuit diminishes, the liuid which has been forced into the valve can return to the primary circuit only through the restricted orice since the alternate path through conduit 172 permits the liow of uids only in the opposite direction. Thus, the valve 100 does not return instantaneously to a new position upon reduction of the pressure in the primary hydraulic circuit; instead the restoration of the valve 100 is gradual so that the restoration of pressure in the auger advance circuit is correspondingly gradual, whereby sporadic motion of the auger is avoided.

v Other types of dampening apparatus than shown in Figure 1 may be employed in the conduit 110.

. Another interesting application of the present invention is to the eld of continuous mining machines which also have two independent movements powered by independent hydraulic circuits. The cutting operation normally is eiiected by means of one or more rotating cutter bars or by means of an endless chain itted with cutter bits moving around two drums. 'Ihe advance motion in cutting machines usually is effected by moving the entire mining machine forward by means of its endless treads or conventional wheels. Where the advance motion is powered by a hydraulic motor, the present invention is applicable to continuous mining machines.

yIn continuous mining the advance of the machine is limited by the capacity of the cutting tools to remove coal from the working face. With the present invention, the rotating cutting tools can be operated by hydraulic motors which at all times are developing a torque iust short of their maximum design torque.

' The control valves of the present invention are installed in the advancing hydraulic circuits of the continuous mining machines and operate in response to pressure loads of the hydraulic circuit controlling the cutting tools. Since the machine is self-regulating, relatively inexperienced personnel can operate the machine at maximum efliciency without the danger of stalling the hydraulic motors and without the danger of breaking or unnecessarily abrading the cutter bits. When the cutter bits become dulled through use, the machine itself adapts its rate of advance into the working face to compensate for the diminished cutting capacity of the cutter tools.

The use of this invention in continuous mining machines is briey illustrated in Figure 9 which is a schematic drawing of a typical continuous mining machine having hydraulic power units for both the cutting operation and the advance operation. The continuous mining machine, generally indicated by the numeral 500, has a cutter head 501 and is mounted upon endless treads 502. The cutter head may be of the revolving drum and cutter chain type, the rotating cutter arm type, or any other type which employs a rotary motion to effect cutting at the working face. The endless treads indicated in the drawing could be replaced with ordinary wheels. A hydraulic pump 503 is provided to supply hydraulic fluid from a reservoir 504 and a conduit 505 through a feed conduit 506 to a hydraulic motor 507 which powers the cutter head S01. Hydraulic tluid from the motor 507 returns to the reservoir for reuse through the conduit 50S. A pressure relief conduit and valve 509 and an on-oi bypass conduit and valve 510 are provided for the same purpose as those shown in Figure l.

A hydraulic pump 511 supplies hydraulic iiuid from the reservoir 504 and the conduit 512 through the conduit 513 to a hydraulic motor 514 which powers the endless ftread movement. Hydraulic uid from the motor 514 returns to the reservoir for reuse through the conduit 515. A relief conduit and valve 517 and an on-oli by-pass conduit and valve 516 are provided for the same purpose as those shown in Figure 1.

An additional by-pass conduit 518 is provided between the feed conduit 513 for the hydraulic advancing motor 514 and the return conduit 515. A pressure relief valve 519 of the type shown and described in Figure 2 is prt)-I auna-sar vided iii-the e'iidni 518` tdreieve eitc'ess hydraulic iiuid fidr conddit 5153Ar A- pifess'ureetap conduit 52|]i pro-'- vides'hvdruii drhmunicationbetween the primary hy# drauiicf feed cir-'cinc at'- conduit 506 and the operating port ostlie valve sfr-9i. The pressure transmittedrhreugnrhe pressure' tap conduit 524V serves tofregulate the: reliet` set-y ting et the pressure relief vaive 519` as described in'- con:` letion'- with the valve'- shown in- Figure 2;

When the dint-:hind isnioved through'A mine. passage Wayswithits cutterh'ead not' operating,- no pressure is exerted through conduit 520 and hence the valve 5129- permits pressure to bedevel'oped inthe advancing. circuit througlconduit 513; accordingly' the continuous rriinng machine canbe'v moved rapidly onV its endicss ti'e" ds tinfongh-the' niine. However', when thecontinuous niiniiig machine? erigafg'e'di withthe-Working' surf-ace and'- the cutter head setl intooperation; the rate of advance isy attorticllv limited by' the resistanceto' cuttingl en# countered by die' cutter head. Accordingly the maximum` curr-ing torque is developed by the' mining machine at all during the work-ing' motion, yetthemaximumto'r'que is? never'- e'rceeded.v Hence' protective* shear pins are'z not broken",- nor is the machine subjectedV to' thermal overioatlirigof its electrical circuits.- Since the' operator Iis noti requiredto control the; advance*A motion of thecontinuous raining machine, the normally sporadic and ineiticient advance resu'iti-n'gfrom manualoper-ation afVOidd'.-

According to the: provisions of the` patent statutesr I ii'av'e explained. the' princi-ple,- preferred construction,A and mode of operation o my inventionantl: have illustrated and?.described what I now-'consider to' represent itsbest embodiment. However, I desi-re' to' have4 itunderstood'I that,A within the' scope ot'. the appended claims, thein'-Y venteion may be' practiced otherwise than as: specifically illustrated and described.

In a machine'- havin-g aprimary uidmotor- With a pr-imaryfl-uidtfeed' conduit? receiving hydraulic iiuidv frome a' primary source andiasecondary iiuid motor withia' sec ond'axty iiuid-A feedxconduit receiving hydraulic fluid from-z asec'onidary source,l the-improved'hydrauhc circuitz comV prising in combinations a" bypass uid conduit providing a uid path from said secondary iuirh feed: conduit cir; cumventingzsaid secondaryiiuid'V motors valve means havingi an- 'inlet associated;A with said secondarir uid' feedcondui-t and an* outlet associated With said liv-pass iuid: conduit, resilienti'y biased-sealing means within said-'vvalve means for sealing said outlet'` toprevent fiow of fluidy from' said secondary fluid-'.fe'edconduit through said-Y bypass conduit, operating-means associated with-said val-ve means and responsive toa uid pressure 'impressed-there; on. for opposing,- the bias oisaidA sealing means-whereby saith outlet isY opened to admit-fluid from said secondary uid feed-conduitinto said by-pass conduit, a iiuid4 control conduit between said primar-y uid feed conduit and saidoperating means-for impressing the' uid pressurefof.v said'lprimary uid feed conduit onA saidoperating means, and dampening means in said uid' control conduit:V between said-primary fluid feed conduit and'said operating. meansprovidingunrestricted flow ofA uid from said primary fluid feed conduit anda restricted-flow of. uid in the reverse direction.

2. In a control system for a hydraulically operated machine-operabie to both rotate and-advance a--Working element the combination comprising, a fluid pressureactuated:v implement rotating; motor: and afuid pressure actuated implement advancing; motor, ai i-rstsource ot ftuid under apredeterminedxed-constant pressure operable-to actuate said implement-rotating'motor, a'lsecond and-separate source ofE fluidunder a predetermined fixed constant pressure operable to actuate said-imple`- ment advancing motor', a iirst` circuitconnecting said rst source ofA fluid:- undenf pressure-Y Withsaid implement rotating motor-,a second circuit connecting said? second sour-co3 of iiuidunde'r'- pressure. with-said implement ad' vane-ing? motor',- said second circuit:- including a lay-pass: conduit-*,operableto by-pass uid around said implement; advancing motor to thereby reduce saidy work-ing element;L rate ot advance; ow control means positioned insaid: lay-passv circuit, saidA flow control means including mechanicalmeans' biasing a valve means'toward a closed` position; saidl flow control means having a fluidy pressure responsive means to urge saidvalve means toward an: open position, and conduit means connectngqsaidfluid, pressure responsive` means with said rst circuitbetween said ist source of'iiuid4 under pressure and said imple-jment rotating-motor so that control ofv said iiow'` controlj meansinsaid second: circuit by-pass conduit is dependentI upon pressure of` the fiuid on the inlet side of said im. plement yrotating motor.

3. In a control system for ahydraulically operated ma.v chine oper-able to both rotate and advance a Working element the combination comprising, a uid pressure4 actuated implement rotating motor and auid.pressure actuated. implement advancing motor-,- a first source' of iluid underv a predeterminecl iixedr constant pressure operable to actuate said implement rotating motor,- a'l second-,and separate source of uid under a predetermined ixed constant pressure operable to actuate said implenientadvancing motor, aiirst circuit connecting; said.l iirst; source of.- uid under'pressure with said implement; rotating motor, a second circuit connecting said second Source-of uid underpressure with said implementV advancingA motor-g said second 4circuit including a by-pass conduitoperable, to by-pass. fluid around said implementadvancing motor to thereby reduce said-working-element rate of advance,.- flow control means positioned in said lay-passt. circuit, said owcontrol. means. including mechanical means biasing a valve means toward aclosed position, said flow control means. havinga. iiuid pressure responsive means to urge said vaive means toward an' open position, conduit: means connecting said uid prssurev responsive means With said iirst circuit between said rst source of uid under pressure and said implement rotating-motor so that controlof said hou/.control means inrsaid. second circuit by-pass conduit-is. dependent upon pressure-ofl the uid on the inlet side of said implement rotating motor,l and dampening., means in; said conduit, means between said irst circuit and saidV iiovvcontrol.y means, said dmpening meansv constructed and arranged to provide unrestricted iiovv otI uid from said rst'circuit anda restricted fiow of: iiiiid' in the'. reverse direction.

Lt. In a control system forahydraulicallyoperatedfmaf chine operable to both rotatey and advance a Working-clef' ment the 'combination comprising a fluid .pressure actuated implement rotating motor and a iiuidpressure' actuated implement advancingmotona rst` source of uid under a predetermined fixed constant pressureloperable to actuatesaid implement motor, a second and separate source of iiuid under a predetermined-fixed constantfpres sure operable to actuate said. implement advancing-motor,- a first circuit connecting said iirst source ofruid under pressure with said implement rotatingrmotor, a second circuit connecting -saidsecond` source of duid under pressure withf said implement advancing motor, said second circuit includinga by-pass conduit ,operableI to by-pass fluid aroundV said; implement advancing motor. to; thereby red-uccsaid workingl elementrate ofy advance,- iiow`4- control meanspositioned in; saidV by-pass circuiti said flow control means havingahousing with. an inlet'port asso ciated, withssaidsecondcircuit and an outlet port asso--I ciated with saidbv-pa'ss-- conduit, valve means positioned within-saidhousingI for-controlling flow therethrough, re-j silient means-biasing` said valve means towarda closed position, uid pressure responsive' means operable to oppose the biasofsaid resilient-means to therebymove saidvalve means toward an open position,- and conduit meansf connecting said uid pressureA responsive means with said-first circuitbetween saidy rst' source-ofuid under pressure and saidimplement rotating motor sp References Cited in the le of this patent UNITED STATES PATENTS Vickers et a1. May 11, 1937 Joy Nov. 15, 1938 14 Vickers Mar. 17, 1942 Lehman June 1, 1943 Cartlidge Sept. 21, 1943 Jeffrey et a1. Nov. 23, 1943 Paget Nov. 5, 1946 Tucker Ian. 25, 1949 Lewis May 6, 1952 Ernst Aug. 12, 1952 Quintilian Nov. 4, 1952,

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