US2334009A - Mining machine - Google Patents

Description

Nov. 9, 1943. R. K. JEFFREY 2,334,009

MINING MACHINE Filed May 23, 1941 5 Sheets-Sheet 1 f/VVE/VTOE, EOBEQT K. JEFFREY.

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Nov. 9, 1943. R. K. JEFFREY 2,334,009

MINING MACHINE Filed May 23, 1941 5 Sheets-Sheet 2 f/VVE/VTOE, 120mm K. JEFFREY,

N 9,"1943-, 1 R. K. JEFFREY MINING MACHINE 5 Sheets-Sheet 5 Filed May 23 1941 f/Vl/E/VTOE, BOBEQT K. JEFFREY. Maw 17.

ATTY R. K. JEFFREY MINING MACHINE Nov. 9, 1943.

5 Sheets- Sheet 4 Filed May 23, 1941 [AA/E/VTO/Q;

120mm K. JEFFREY,

R. K. JEFFREY MINING MACHINE Nov. 9, 1943.

Filed May 23 1941 5 Sheets-Sheet 5 j/Vl/E/VTOE,

ROBERT K. JEFF REY,

Patented Nov. 9, 1943 -r 2,334,009 MINING MACHINE Robert K. Jeffrey, Columbus, Ohio, assignor to The Jeffrey Manufacturing Company, a cor-.

poration of Ohio Application May 23, 1941, Serial No. 394,812

21 Claims.

This invention relates to a mining machine and particularly to an improved hydraulic control system'ior a mining machine.

An object oi the invention is to provide a mining machine in which the feed rate of the kerf cutting mecham'sm is automatically adjusted to compensate for the load thereon thereby to prevent overloading of the driving motor for. said kerf cutting mechanism.

Another object of the invention is to provide an improved hydraulic control system for a mining machine in which hydraulic means are provided to effect a feeding of the keri cutting mechanism in which the rate of liquid supply to the hydraulic feeding mechanism is adjusted in accordance with the current flow in the driving motor of the kerf cutting mechanism to prevent overloading of said driving motor.

A further object ofthe invention is to provide an improved power operated hydraulic control valve.

Still another object of the invention is to provide a solenoid operated hydraulic control valve which is adapted to control the rate of fluid flow therethrough in accordance with the current flowing in an electrical circuit.

Another object of the invention is to provide a combined solenoid and mechanically operated hydraulic controlling valve adapted to vary progressively the rate of flow of hydraulic liquid therethr'ough.

Other objects of the invention will appear hereinafter, the novel features and combinations being set forth in the appended claims.

In the accompanying drawings,

Figs. 1, 2 and 3 placed end to end comprise a plan view of a mining machine incorporating the features of my invention;

Fig. 4 is a digrammatic plan view of the mining machine illustrating various horizontal swinging cuts which can be made thereby; I

Figs. 5 and 6 are diagrammatic elevational views of the minin machine showing several positions of adjustment of the cutter bar;

Fig. '7 is a piping diagram of the hydraulic control system of my invention;

Fig. 8 is a front elevational view of a power operated automatic volume control valve incorporated in the system of Fig. '7 with parts shown in section;

Fig. 9 is a sectional view taken on the line 9--9 of Fig. 8 looking in the direction of the arrows;

Fig. 10 is a sectional elevational view taken on the line ,|0l0 of 9 looking in the directionof the arrows;

' Fig. 11 is a sectional elevational view of a pilot control valve employed in the hydraulic system of Fig. 7

Fig. 12 is an enlarged view partly in section showing the structure of an adjusting mechanism of the pilot valve of the control system of Fig. 7; and I Fig. 13 shows a modification of the system of my invention, being particularly a modification of the apparatus disclosed in Fig. 7.

This application is a continuation inpart of my application, Serial No. 252,801, for a Mining machine, filed January 25, 1939.

The mining machine herein disclosed constitutes an improvement upon the mining machine disclosed in the application of Robert K. Jeffrey et al., Serial No. 206,448, filed May 6, 1938, now Patent No. 2,263,779, dated November 25, 1941, entitled Mining machine. It is-to be understood that unless a contrary'fact is indicated, the structure of the mining machine of the instant application follows the structure of the mining machine disclosed in complete detail in said above mentioned application of Robert K; Jeffrey'et al.

It has been found -in practice that there is a tendency for kerf cutting-mechanismto overload the driving motor therefor under certain conditions, as the kerf cutting'mechanism is fed into the coal while cutting a kerf either during a shearing; sumping or swinging operation.

The mining machine disclosed herein and constituting my invention operates automatically to control the feed rate of the kerf cutting mechanism to maintain theload on the driving motor substantially constant 'at its rated value, at which it has a maximum efficiency, which drives said kerf cutting mechanism, by controlling the volume. of hydraulic fluid delivered to the feeding hydraulic motor or motors at a rate which is entirely independent of the pressure of the hydrau- 'lic fluid, being controlled only by the volume oi flow thereof. 7

Referring particularly to Figs. 1, 2 and 3 which together comprise a plan view of the mining machine, and to Figs. 4, 5 and 6, which show the mining machine diagrammatically, it will be seen that said machine comprises a main frame 30 including atrack mounted truck 3| provided with whee1s32 adapted to ride upon mine track rails 33.

Mounted upon the said truck 3| for adjustment about an upright axis is a turntable Biadapted to be swung about said upright axis by a pair of oppositely acting hydraulic piston motors 35.-

Pivotally mounted upon the turntable 34 for adjustment about a horizontal axis is a supplemental frame 36 formed by a housing 31 of an electrical driving motor 9| (see Fig. '7), contained therein, to which is rigidly attached a gear housing 38 provided with an integral and downwardly sloping neck to which is journaled gear housing 39; that is, the motor housing 31, gear housing 38 and neck carrying housing 39 are all rigidly attached together to form the supplemental frame 36. Said supplemental frame 36 is pivotally attached to the turntable 34 by journal bearings 46, 40 at the rear end of said supple! mental frame 36 and turntable 34.

Also forming a part of said supplemental frame 36 is a pair of spaced arms or brackets 4| between each of which arms 4| and the motor housing 31,

there is trunnioned the housing of a hydraulic piston motor 42, the piston rod of which i jour. naled to the turntable 34. The hydraulic piston motors 42 are adjustable to swing the supple- 1;

mental frame 36 about the horizontal axis provided by the journal bearings 46, thereby to adjust the elevation 01' the forward end .01 said supplemental frame 36.

The rear end of the main frame 36 forms a supporting platform' 55 upon which is mounted an electric motor 43 which serves a number of purposes. Said motor 43 drives a hydraulic pump 44 of the hydraulic control system and also drives the wheels 32 of the truck 3! to tram the mining machine along the'mine railsthrough an appropriate gear train including clutch shifting mechanism 45 which is adapted also to effect a driving connection from the hydraulic motor 46 to said wheels 32 to effect low speed sumplng of the entire mining machine while cutting a kerf. That is, the clutch shifting mechanism 45 includes a. shiitable clutch member 41 which is operable from operating handle 43 through a gear train including pivoted shaft 49, rod 5!), bell crank 5|, rod 52 and bell crank shipp r 53 to effect a driving connectionto the wheels 32 by way of reduction gear 54 either Irom the electri v motor 43 forhigh speed during tramming or the. machine or from the hydraulic motor 46 for low speed during sumping thereof.

.Also mountedupon the platform 55 is an electrical cable reel mechanism 56: which winds in and pays out the electric cable for supplying current to electric motor 43 and which is driven by the drive mechanism 51 including a, control clutch 56 operable Irom' appropriate operating mechanism including hand .9-.

It is to be noted that the operating handles 48 and 59 are positioned at an operatorsstation at which there is an operators seat 66' also adjacent to which is a brake-handle 61 of a brake mecha-i nism associated with the wheels 32 of truck 31-. There is'also mounted upon the platform 55 a steel draft cable mechanism 62 which may be operated from the electric motor 43 through an appropriate drive including gears 63- to aid in the sumping action of the mining machine particularly when operating under difllcult eonditions or to anchor the mining machine in the mine against retrograde movement.

Also mounted on an upright plate at the torward end of the platform 55 is a two-waycontrol valve mechanism 64 having; two valves therein one of which is controllable to swing the turntable about its upright axis by controllingthe hydraulic flow of fluid-to hydraulic motors 35, the other or which is operable to control the hydraulic motor 46 to efiect the surnping of the entire mining machine alongthe track rails 33.

The outer end of the neckhousing 39 terminates in and forms a turnover head 65. Mounted upon the turnover head 65 for swinging movement about an axis which is perpendicular to the plane thereof is a kerf cutting mechanism 66 comprising a flat elongated cutter bar 61 around which is adapted to move an endless cutter chain 68 carrying cutter bits 69. The cutter chain 68 is driven from a drive sprocket, in a manner well understood in this art, at the rear end thereof which drive sprocket is driven from the electric motor 9| (Fig. 7), contained within housing 31,

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through appropriate drive gearing which extends through the gear housing 38, neck housing 39 and turnover head 65. It may be stated that the sole function of the motor contained within housing 31 is to drive the cutter chain 69 of said kerfc'ut- I ting mechanism 66.

To provide for controlled swinging movement of the kerf cutting mechanism 66 about its upright pivotal axis with respect to the turnover head 65,*a pair of reversely operating hydraulic piston motors 19'is provided; the cylinders of which motors are pivotally attached to an operating bracket 12 which is. rigidly. attached to the cutter bar 61. It is thus manifest that byalternate reverse operation of the two motors "the cutter bar 61 may be swung .in reverse directions.

To provide for the swinging of the cutter bar 61 in a plane perpendicular to its own plane, particularly so that said cutter bar 61 may be horizontally positioned, for example in any of the positions illustrated in Figs. 5 and 6- of the drawings for different positions of adjustment of the supplemental frame 36, said cutter bar 61 is pivotally attached to the turnover head 65 on a transverse axis which is parallel to the plane of said cutter bar. To effect swinging movement of said cutter bar 61 transversely of its plane there is mounted on the turnover head 65 a hydraulic piston motor 13 the piston rod of which is attached to a sliding head 14 to which are connected operating arms 15 attached to opposite plates 16 I which at. their bottoms form a journal upon which the previously mentioned bracket 12 is journaled for swinging movement and which acts to support the kerf cutting mechanism 661mm the turnover head 65. It is evident that expansion and contraction of the hydraulic pistonmotor 13 will therefore produce a swinging movement-of. the cutter bar 61 in an are perpendicular to its own plane. It is thus to be noted that the cutter mechanism 66 may be adjusted for swinging movement with respect to the turnover head 65 about axes that are disposed at a right angle with respect to each other. i

To provide for the turning over of the head 65 so that the cutter bar 61 may be adjustedto a bottom cutting position, as illustrated for exam,-

ple in Fig. '6 of the drawings, or to a top cutting; example in Fig. 5; of

journaled on the aforementioned integral neck of the supplemental frame 36, and is provided wlth means for rotating, it through almost butnot quite, 360 degrees, including a rotary t ne-oi by? draulic motor 11 (see Fig. 2), which is adapted to rotate the neck housing 39 through, appropriate gear reduction mechanism preferably including,

worm gearing.

It may be stated that between the neck and its housing 39 there is a stop means which prevents its own plane in,

360 degrees of rotation but which permits the adjustment of the cutter bar 61 to any of the aforementioned positions.

To provide for the flow of hydraulic fluid to the hydraulic motors and 13 which, of course,

rotate with the turnover head mechanism 65 and thus rotate with respect to the supplemental frame 36, flexible hose hydraulic conduits 18 are provided which wind upon winding reel 19 which is driven to rotate with the neck housing 39 by a driving cable 80.

It may additionally be pointed out that mounted on one side of the gear housing 38 of the supplemental frame 36 is a four-way hydraulic control valve 8| including four slide pistons which slide pistons are individually controlled by four operating handles 82 (Fig. 2) positioned at an operators station adjacent the rear end of the supplemental frame 36 and attached to the motor housing 31. There is one handle 82 for operating each of the pistons of the four-way valve 8|.

It may be stated that one of said handles and one of said slide pistons is individual to the two motors 10, another individual to the motor 13, another individual to the motor 11 and another individual to the motors 42. In other words, motors 42, TI, 10 and 13 are individually controlled by the handles 82 which control individual pistons of the four-way valve 8|.

It may also be mentioned that the previously mentioned two-way control valve 64 which is carried by the rear platform has two slide valves one of which is individual to the hydraulic motor 46 to control the sumping of the entire mining machine and the other of which is individual to the hydraulic piston motors 35 for swinging the turntable 34, the latter of which is controllable from two positions, one of which is adjacent the control station where handles 82 are located, by virtue of handle 83, the other of which is controllable from the position near the operators seat by handle 84. This is desirable because during tramming of the mining machine through the mine it is sometimes necessary to swing the supplemental frame on the turntable 34, particularly while rounding curves in the mine. All of the hydraulic motors are controllable from the operators station adjacent the handles 82, for this is the normal position of an operator while the machine is cutting a kerf in the mine.

As was previously pointed out, it is desirable to regulate automatically the feeding movement of the kerf cutting mechanism 86 and this is preferably done to maintain a substantially constant ampere load on the driving motor 9| (Fig. '7), contained within housing 31. In practice, the mechanism is preferably adjusted so that the cutter mechanism is driven at full speed until the current reaches approximately its full load rating, whereupon the feed rate of the kerf cutting mechanism is decreased until the motor 9| again draws its rated current, thereby preventing overloading thereof.

It is, of course, evident that with this automatic system the kerf cutting mechanism is operated at the maximum rate possible without undesirable overloading of its driving motor 91 which is the motor in housing 31, so that when easy cutting is encountered, the feed rate is increased and when hard cutting is encountered the feed rate is reduced. Furthermore, when the driving motor for the cutting mechanism is not operated at all, or is merely running light as when no cutting operation is being performed, the feed rate for adjusting the various hydraulic piston motors is at a maximum thus providing for a high rate of adjustment to position, the cutter mechanism for kerf cutting.

The apparatus which provides for this automatic control as above set forth, is disclosed in detail in Figs. 8 to 12 of the drawings, which will now be described in connection with Fig. '7 of the drawings which shows the hydraulic control system.

Referring first to Fig. 7 of the drawings, it is to be seen that the hydraulic control system comprises a tank or reservoir for the hydraulic fluid or oil from which extends a feed pipe 88 leading to four reversely connected valves 8'! interconnected to the hydraulic pump 44 from which valves 8'! there extends a pressure pipe or conduit 88. The valves 81 are so connected that the pressure in the pipe 88 is always positive regardless of the direction of rotation of the reversible pump 44. In this connection it may be stated that driving electric motor 43 is of the re versible type so that the mining machine can be trammed in reverse directions and consequently the pump 44 is subjected to rotation in reverse directions, as shown in Fig. 1.

The pressure pipe 83 leads to and through a combined high pressure relief and automatic volume control valve mechanism 203, the detailed structure of which is disclosed in Figs. 8, 9 and 10 of the drawings, and hereinafter described in full detail.

As a general description, it may be stated that the automatic volume control valve mechanism 203 is operative to control the volume of fluid delivered to the operating hydraulic motors of the hydraulic system to maintain a substantially constant current flow in the electric motor contained in housing. 31, which is illustrated at 9| in Fig, '7 of the drawings.

Leading from the automatic volume control valve 203 is pressure pipe or conduit 92 which delivers hydraulic fluid under pressure to the two-way control valve 64. The two-way control valve 64 is effective to control the selective feeding of hydraulic fluid in reverse directions to the hydraulic piston motors 35 and to the rotary hydraulic motor 46; there being, of course, an individual piston for the two motors 35 on the one hand and the motor 46 on the other.

It may be stated that, as above described in complete detail in the application of Robert K. Jeffrey et a1., S. N. 206,448, now Patent No. 2,263,779, dated November 25, 1941, the two motors 35 and the single motor 46 are capable of operation at the same time or individually due to the particular construction of the control valve 64.

A return pipe 94 is provided to return hydraulic fluid from the pressure relief valve 203 to the reservoir 85 whenever said pressure relief valve 203 operates to relieve excessive pressure in the pressure pipe 88.

It may also be mentioned that leakage drain pipes 95, 96 and 91 are provided for the motor 46, two-way valve 64 and pump 44 to return any excess fluid, such as is received due to seepage past the bearings thereof, to the reservoir 85 by way of junction block 98.

That portion of the hydraulic control system above described which is to the lower left hand side of the line 99 in Fig. 7 of the drawings, is all mounted on the platform 55 and therefore is stationary with respect to the main frame of the mining machine. The portion of the system now to be described is mounted for adjustment 11 of the drawings.

with respect to the main frame and is carried by the supplemental frame 36 or some structure which is attached to move therewith.

Extending to the four-way control valve 8| is a pair of flexible hydraulic fluid conduits or hoses I and IOI, of which the former is a. pressure hose leading from the valve 64 and the latter a return hose which leads to the junction block 98 and thence to the reservoir 85. It may be stated that pressure is delivered to the hose I00 from the pressure pipe 92-without regard to the position of any of the slide valves of the twoway valve 64. Said conduits or hoses I00 and IOI lead to and from the four-way control valve BI which is provided with four individual slide valves as above set forth, one of which is operated to control the motor 11, another of which is operated to control the two motors 42 in parallel, still another of which is operated to control the motor 13 and the fourth of which is operated to control the reversely connected motors 10.

To provide for the floating of the cutter bar 61 on-it pivot, when positioned in a vertical plane which is desirable for the cutting of vertical kerfs while the mining machine is sumping along a curved mine track, a by-pass valve I02 interconmeets the conduits leading to the hydraulic piston motor 13 which in cooperation with an equallz'ing valve I 03, also connected between said conduits, permits the floating of the piston in said motor 13 whenever valve I02 is open. As above described, the reel 19 provides for the rotation of the hydraulic piston motors and 13 with the neck housing 39.

It is also evident, of course, that motors 10 must swing about the axis of the turnover head 65 which is parallel with the plane of the cutter bar 61. To provide for the continuation of the fluid conduit during this swinging motion a pivotally mounted packed bearing I04 is provided which forms continuing paths leading to the motors 10 for various positions of adjustment of the cutter mechanism 66 with respect to the head 65.

The armature circuit of the electric motor 9I has connected in series with it a solenoid I19 with which there is associated a plunger I which is connected to an adjustable helical spring I8I by a shaft I82. Shaft I82 is pivotally attached to an operating lever I83 pivoted at I84.

Associated with the lower portion of lever I83 is a pair of oppositely positioned cushioning spring abutments I85, the detail structure of which is illustrated in Fig. 12 of the drawings. Each of said spring abutments I85 comprises a casing I86 carrying a stop I81, and within which is mounted a slide piston I88 to which is attached an outwardly extending contact pin I89 adapted to contact the lever I83 after a predetermined pivotal movement thereof. Also, in the casing I86 is an adjustable cap I90 the position of which may be adjusted by adjusting screw I9I.

Between the slide piston I88 and the cap I90 is a helical spring I92. It is manifest that by adjusting the cap I90 the tension on the spring I92 may be varied thus varying the amount of current that must flow in the solenoid- I 19 to ad-- just the position of the lever I83.

The lever I83 controls a pilot valve I93, the structure of which is disclosed in detail in Fig.

Said pilot valve I93comprises a casing I94 provided with a central cylindrical bore I95 closed at one end by a plug I96 and having therein a slide piston I91 provided portion of the bore I95 with an operating rod I 98 which is attached to said lever I83 and extends from the bore I95 through a sealing gland I99. The pressure pipe 88 has a branch 88 which leads to thecentral thereby providing hydraulic fluid at this position. Leading from the bore I95 is a pipe or conduit 200. Forwardly and rearwardly :of the piston I91 are drainage ports which lead to pipe or conduit 20I which, inturn, is connected to the junction block 98 and thence to sump 85.

It is manifest from reference to Fig. 11 of the drawings, that with the piston I91 in theposition illustrated fluid pressure will not be supplied to the pipe 200 but said pipe .200 is free to drain fluid to conduit 20I. However, when said piston is moved to the extreme right, as viewed in said Fig. 11, in response to a predetermined current flow in solenoid119, conduits 88' and 200 will be in communication through bore I95 to sup-. ply hydraulic fluid under pressure to said conduit 200 which leads to a power operating mechanism 282 for volume control valve mechanism 203 which-is rigidly attached to the combined high pressure relief and automatic volume control valve structure 203. When the current flow in solenoid I19 is below a predetermined value, piston I91is moved by the springI8I to the left, as illustrated in Figs. 7 and 11 of the drawings, to permit a flow of fluid from pipe 200 to drainagepipe 20I, as aforesaid.

The power operating mechanism 202 comprises a main casting 204 provided with a central bore 205 which intermediate its ends communicates with a central chamber 206. Within the bore 205 and extending across the chamber 206 is an operating piston 201 the head end of which communicates with and extends into a chamber 208which is an enlargement of the bore 205. The aforementioned pipe or conduit 200 communi- 'cates with the chamber 208. At the lefthand end of the bore 205, as viewed in Fig. 8 of the drawings, there is a helical spring 209 which abuts the piston 201 and urges it to the right, as viewed in Fig, 8, which, it may be stated, corresponds to the full open position of the automatic volume control valve 203.

The casting 200 is provided with opposite heads 2! and 2 to close the bore 205. The piston 201 is provided with an elongated piston position indicator 2I2 which is rigidly attached thereto and which slides through an aperture in gill: head 2 made fluid-tight by a packing gland Piston 201 also has a by-pass passageway 201 which provides a movement limiting means to connect chambers 208 and 206 when piston 201 moves the desired maximum amount against spring 209.

To prevent a compression of air in the lefthand portion of the bore 205 as the piston 201 reciprocates, said piston 201 is provided with a groove 2I3 which extends from the lefthand end thereof to an upright notch 2 (see Fig. 9), formed in said piston 201 for a purpose to be described. Also connected to the chamber 206 is a drain pipe 94 which connects to the drain pipe 94 thereby draining any overflow from the chamber 206 to the sump 85. V

Removably attached to the casting 204 of the power operating mechanism 202 is a casting 2I5 (see Figs. 9 and 10) of the combined high pressure relief and automatic volume control valve mechanism 203; which at its bottom is provided with a cylindrical bore 2I'6 within which is an eccentric control cylinder 2II provided with a tapering volume control groove 2 I8. The bore 2|6 forms a chamber, orifice or passageway into which the hydraulic liquid is adapted to flow by way of inlet port 2I9 from pressure pipe or conduit 88 and from which said hydraulic liquid is adapted to flow to pressure pipe or conduit 92 by Way of outlet port 226. The angular position of the cylinder 2|1 controls the effective size of the opening, chamber, orifice or passageway connecting ports 2I9 and 229.

To provide for the angular adjustment of said cylinder 2I1 it is provided at one end with an operating shaft 22I to which is keyed an operating arm 222 which is provided at its upper end with a roller 223 mounted upon a shaft 224. The roller 223 extends into the previously mentioned notch 2|4 of the piston 261. It is thusinanifest that straight-line motion of the piston 201 is translated into this rotary motion of the cylinder 2|1 and the position of said cylinder 2|1 determines the effective size of the opening,

chamber, orifice or passageway through which the hydraulic liquid flows from conduit 88 to conduit 92. A seepage pipe 95 is connected to drain pipe 95 to drain hydraulic liquid which seeps by the right hand end of cylinder 2|1 as viewed in Fig. 9 of the drawings.

It may be mentioned that in Fig. '1 of the drawings, the power operating mechanism 262 is shown separated from the high pressure relief and Volume control valve 203 in the interest of clearness, but in practice they are preferably rigidly attached together as illustrated in Figs. 8, 9 and 10 of the drawings, with the shaft 22I rigidly connected to the cylinder 2I1.

The additional structure of the high pressure relief valve 283 includes a central cylindrical bore I64 in casting 2|5 within'which is a control piston I65 moved downwardly by a relatively weak helical spring I66 which bears against a closure plug I61 for the bore I64.

At the bottom of the bore I64 and at a position generally surrounding the piston |65 when the latter is in its normal position, is a chamber I69 which is connected to return pipe 94 by a passageway I19. A bore |1| provid'esa communicating passageway between the bore 2I9 and the bottom of bore I64 thereby to subject the bottom of the piston I65 to the pressure in the bore 2I9 which, of course, is the same as the pressure in the pipe 88.

Interconnecting the bore I64, at a position above that assumed by the piston I65 during any operating condition, and the passageway I10 which leads to the drain pipe 94, is a passageway I14 leading to chamber I15 which in turn leads to passageway I16. An adjustable ball check valve I11 is provided in chamber "5 and will release upon a predetermined pressure in the bore I64 above the piston I65.

The pipe or conduit ISI 7 pressure in the pressure pipe 92 to the bore I64. Consequently, the pressure on top of piston I65 is normally equal to that in pipe 92 and the pressure on its bottom is equal to that in pipe 88. The pressure drop in the fluid flowing through groove 2|8 for any given effective size opening is proportional to the volume of hydraulic liquid flowing therethrough. This pressure drop is not very great, but during normal operation is sufficient to overcome the weak spring I66, and may be of the order of twenty or twenty-five pounds per square inch, thereby lifting the piston I65 an amount to provide a communicates the by-pass for the excessive hydraulic fluid not desired to operate one of the hydraulic motors 35, 42, 46,10 or 11 leading to pipe 94 by way of chamber I69 and bore I1I to keep a substantially constant load on motor 9|. The piston I65 acts under the influence of weak spring I66 to control the amount of fluid by-passed at such a value as to insure an adequate supply to the hydraulic motor being operated to keep motor 9| fully loaded, it being evident that in the absence of sufiicient pressure drop across groove 2I8, piston I65 will be moved downwardly to reduce or shut off the icy-pass.

To provide a safety valve against excessive pressure in the system, as when a hydraulic motor reaches the end of its stroke and hydraulic fluid continues to be fed to it, whenever the pressure in pipe 92 becomes excessive at any value which may be adjustably determined by the check valve I11, an example of which is 1200 pounds per square inch, the check valve I11 will operate to relieve this pressure and permit a flow of the hydraulic fluid to the return pipe 94. The flow of this high pressure fluid from the conduit I6I into the bore I64 is through a passageway I18 which is a very restricted area thereby causing an appreciable pressure drop whenever the fluid begins to flow through said passageway I18.

After the ball valve I11 has cracked and the high pressure fluid begins to flow to the return pipe 94 the pressure in the bore I64 above the piston I65 will fall below that on the bottom of said piston I65'due to said pressure drop through passageway I18 which will result in the fluid under pressure on the bottom of piston I65 moving it upwardly against the action of the weak spring I66, to provide a direct communication between the bore |1I and "the passageway I16 by way of chamber I69. This, of course, will provide a direct communication between the conduits 88 and 94 thereby providing a direct return path for high pressure fluid in the line 88 to the return pipe 94. Whenever the pressure in the pressure pipe 92is returned to normal, check valve I11 will close and the parts of the high pressure relief valve 203 will be returned to their normal positions as illustrated in Fig. 10 of the drawings.

In the operation of the mining machine incorporating the hydraulic control system above described, the reversible electric motor 43 may be connected by a direct mechanical drive to the wheels 32 of the mining machine for tramming in reverse directions. Furthermore, the motor 43 whenever in operation drives hydraulic pump 44 of the hydraulic control system to provide fluid for said control system in the pressure conduits 88, 92 and I06 at all times. The hydraulic fluid under pressure as delivered by said pump 44 is employed for sumping the kerf cutting mechanism 66 while performing a sumping cut by driving the rotary hydraulic motor 46 which may be connected to drive said wheels 32, as aforedescribed. During any sumping operation the cutter chain 68 ofthe kerf cutting mechanism '66 is, of course, driven by the electric motor 9| which is within the housing 31. As previously mentioned, the electric 'motor 9| does not driv any other portion of the mining machine.

It is, of course, manifest that before any kerf cutting operation is to be performed, the cutter bar 61 must be adjusted to a desired position. This may be done with the motor 9| deenergized, or it may be done with said motor running light, under which conditionsthe automatic vol plemental frame 36 about its horizontal axiswith,

respect to the turntable 34, hydraulic piston motors 10 for swinging the, cutter bar 61 with respect to the turnover head- 85 in-its own plane,

hydraulic motor 13 for swinging said cutter bar.

transversely of or at right angles to its own plane, and rotary hydraulicmotor. 11 for turning over the head 65, neck housing-.39 and all parts rigidly attached to them. I

In the performance of the sumping operation as previously mentioned, it is, of course, evident that the cutter mechanism 68 is in operation and driven by the electricmotor 9| in housing 31 to drive the continuous cutter chain 68. The sumping operation may be performed in a horizontal plane which plan may lie anywhere between the top or roof of the mine room, for example as illustrated in dotted lines in Fig. 5 of the drawings, and the bottom or floor of the mine room, for example as illustratedin the full line position at the bottom ofFig. 6 of the drawings. Furthermore, a horizontal sumping cut may be made at any intermediate position between the two extreme positions above mentioned.

In a wide entry such as one where the distance between the ribs is approximately equal to twice the distance from the turntableaxis to the outer end of the cutter bar, a continuous horizontal arcuate cut may be made on the turntable axis,

as illustrated by the semi-circle in full lin in Fig. 4. In entries not so wide the successive arcuate horizontal connecting cuts illustrated by the dotted lines in Fig. 4 may be made, the turntable and supplemental frame 36 being held in adjusted position relative to the stationary truck 3| for each such successive arcuate cut. The feed of the kerf-cutteron the turntable axis is effected by means .of the hydraulic motors 35, 35 and the horizontal kerf cut is on a relatively long radius. The feed of thekerf cutter'on its own pivot is effected by means of the hydraulic motors 10, m and thehorizontal kerf cut is ona shorter radius. l I i In narrow entries it is preferred first to make a sumping-cut by traction feed along the mine track. That is, the whole machine is moved along the mine track at feeding speedtc cause the kerf-cutter to cut ,a kerf rectilinearly parallel to the minetrack in continuation of one of the ribs of the mine entry. This is followed by arcuate feeding horizontally either on the tumtable axis or on. the pivotalaxis of the cutter bar while the truck is stationary on the mine.

track. Finally, a rectilinear withdrawal cut, is made by traction feed to finish the horizontal kerf along the opposite rib of the mine entry. During the rectilinear sumping and withdrawalouts parallel to the mine track, the cutter bar is'held rigidly connected to the supplemental frame 36 and the latter is heldrigidly connected to the truck 3|. Horizontal kerfs may b cut between the ribs of the mine entries of various widths at any elevation between the floor and the roof.

Vertical or shear kerfs may be out between the floor and roof of mine entries of various widths anywhere between the ribs thereof. For such shearing cuts th cutter bar. is adjusted to a vertical plane by means of the rotary hydraulic motor 11 and the shear kerf completed by rectilinear sumping and withdrawal cuts parallel to the mine track connected by arcuate cuts either on the pivotal axis of the cutter bar or on the y axis of the trunnions 40, 40 (Figs. 2, 5, 6), the sumping and withdrawal cuts being effected by traction feed or by movement of the whole machine along the mine track at feeding speed and the upright arcuate cuts being made either by the motors I0, 10 or the motors 42, 42, while the truck is stationary on the mine track.

Also for adjustment purposespreparatory to motors 35, 42, 10 and 13 are all of the double acting type so that they may operate positively in reverse directions by reversing the direction.-

of flow of the hydraulic fluid thereto.

It is to be particularly noted that when any of the hydraulic piston motors such as motors 35,, '42, 10, 13 or 48 are in operation and the electric driving motor 3! which drives the kerf cutting mechanism 66 is in operation, and a kerfis actually being cut thereby placing a load on saidmctor Bl, thev automatic control valve mechanism. 203 is effective to maintain the feed rate of the cutter mechanism 66 at a value such as to maintain the current or, in other words, the load on the motor 9| within safe limits and at a substantially constant value.

In the system of Fig. 7 whenever the mining machine is performing any kerf cutting opera-- tion by the operation of any of the motors 35, 42, 46, 10 or. '13, the current flow in the motor 9| flows through, the solenoid I13 to energize it. Aslong as this current is below a predetermined value, as determined by the adjustment of the'spring Ill and the spring abutments I85, which is preferably the rated load of said motor 8|, pilot valve I93 is operated to the position illustrated in Figrll and the volum control valve 283 is at full open position. Thisis generally only during adjustment or starting, for during normal operation the feed rate for full volume of hydraulic fluid would be at such a value as to overload motor 9| even for the very softest coal. Consequently, during normal operation as soon asthe currentflow to motor 9| reaches the predetermined value, preferably rated value,

pilot valve I93 is operated to connect branch conduit-88 and conduit 200 thereby supplying hydraulic fluid to the chamber 208 of power operating mechanism 202. Piston 201- is then moved to the left, as viewed in Fig. 8 of the drawings, or to the right, as viewed in Fig. 7 of the drawings, to adjust the cylinder 2H thereby reducing the effective size of orifice or opening 2|8 which produces an increased pressure drop between pipes 88 and 92, which is also realized between the top and bottom of piston I65, thereby lifting it against spring I66 and by-passing a portion 7 of the hydraulic liquid thereby reducing thevolume of the hydraulic fluid supplied to the pressure conduit 92 and to whatever hydraulic motor is performing the feeding, operation of the kerf cutting mechanism 66. This action will take place until the feed rate of the kerf cutting mechanism 66 is reduced so that pilot valve I93 is returned automatically to its balanced position with pipe 200 sealed by the right hand boss of piston I91, in which the magnetic pull on plunger I80, due to the flow of a predetermined amount of current therethrough, equals the pull thereon due to spring I8I, which will stop the movement of piston 201 of automatic power operating mechanism 202 which will be locked in this position of adjustment and hold the control cylinder 2I'I in this predetermined position.

It is, of course, evident that continued variations in the load on the motor 9! will cause continued operations of the solenoid I19 with resulting operation of the pilot valve I93 either to produce an additional decrease in the rate of fluid flow to the hydraulic feeding motor or to increase said feed rate, to maintain substantially constant the rate of current flow in the motor 9| and solenoid I19. In short, cylinder 2!! is moved by power under the control of solenoid I19 to such a position that the load on motor 91 is limited as to a maximum value in that the feed rate of the kerf cutting mechanism 86 is adjusted by the current flow through said motor BI to keep said motor 9| operating at substantially full load, and thus maximum efficiency, at all times.

To reiterate briefly, it is manifest that with the hydraulic control system of my invention the hydraulic motors for adjusting the cutter bar 6! to any position of adjustment preparatory to the cutting of a kerf are supplied with a-maximum volume of hydraulic fluid, thus insuringtheir rapid movement to the desired positions of adjustment which, of course, are effected without any load on the kerf cutting mechanism or upon its driving motor SI, since these adjustments will be effected ordinarily with the driving motor 9| de-energized, or under any conditions, operating appreciably short of its rated load; I

Once a kerf cutting operation is started and throughout the continuous operation of any kerf cutting operation involving the hydraulic motors which ar employedto adjust the cutter bar 6'! during the cutting of a laerf, the energy supplied to the driving motor 9!.

of the kerf cutting mechanism. 56 is employed, for example, by feeding the current through a'solenoid, to control the feed rate of the kerf cutting mechanism to maintain the current flow in the.

driving motor 9| substantially constant.

As was previously mentioned, it is preferred that the fluid delivery to the feed motor, whichever one it may be, is preferably maintained at a value to maintain a predetermined load on the motor SI which is preferably its rated load value, but to prevent hunting variations of a few percent above and below rated value are without effect and valve I93 is responsive only beyond this range. This is effected by adjusting cushion means I85. Therefore, the feed rate of the kerf cutting mechanism is automatically adjusted to prevent an overloading of the driving motor 9! for the kerf cutting mechanism and at the same time to operate it at its maximum efficiency.

It has been found in practice that a high pressure relief valve to' by-pass fluid from the pump of a fluid pressure system for kerf cutting machines does not act properly to protect the cutter chain driving motor, and this is true even if this relief valve is controlled by the driving motor current because the feeding rate also then depends in part upon the total pressure in the system and not solely on the motor current,

the action of any of The system of control shown in the accompanying drawings, depends only upon variation'of the electric current passing through the cutter chain driving motor 9 I and therefore this system of control provides smooth variations in feed rate and at the same time is entirely independent of the system pressure. Attempts to control the feed rate which involve the system pressure have been found to result in a series of starts and stops in the feed rate which is very unsatisfactory operation.

The fundamental difference between my system and the undesirable system above described is evident from the following fundamental consideration.

In the said undesirable system, the load on the electric driving motor for the kerf cutter becomes effective when it becomes excessive and then it operates to open the hydraulic feed line, like a high pressure relief valve, which practically stops thefeeding of the mining mechanism entirely. This causes a reduced motor current and the hydraulic feed starts again quite suddenly and this usually causes a repetition of the above cycle.

In my system, the fundamental factor is that for every size of opening or orifice provided by groove 2I8 there is a predetermined rate of hydraulic fluid flow to the hydraulic feeding motor doing work. This predetermined rate is maintained entirely automatically because if it tends to increase there will be an increased pressure drop across orifice 2I8 which will lift piston I higher than its previous position to increase the amount of hydraulic, fluid by-passed, While if it tends to decrease there will be a decreased pressure drop across orifice 2 I 8 which will movepiston I lower than its previous positionto decrease the amount of hydraulic fluid by-passed.

Of course, for each position of the cylinder 2|! said opening or orifice provided by groove 2I8 has a predetermined siZe thus automatically demanding a different predetermined rate of fluid flow for each position thereof.

This predetermined fluid flow is fixed for each position of cylinder ZI'I but adjustable by adjusting the position of cylinder 2H and is entirely independent of the hydraulic pressure of the sys-' tem or any variations thereof. In this respect it is fundamentally different from an ordinary by- 1'. pass valve for with such a valve the amount of hydraulic fluid by-passed is a function of both the size of the opening or orifice and the pressure of the system.

The control of the rate of hydraulic flow in my i. system is smooth and continuous for the current in the electric driving motor for the kerf cutter when effective merely adjusts the rate of hydraulic fluid flow to the hydraulic feeding motor by adjusting the position of cylinder 2H, and as above stated the variable factor of the hydraulic pressure of the system is entirely eliminated.

My system of control also includes high pres sure relief valve mechanism, as above described and is shown at 203 in Figs. '7, 8, 9 and 10, combined with the volume control mechanism which is adapted to protect the system against excessive pressures which would be encountered, for example, when a hydraulic motor reached the end of this movement and hydraulic fluid was still being fed to it.

As soon as the by-pass opens in response to excessive pressure the pressure in the motor line drops and the by-pass valve closes again followed by reapplication of the pressure in the motor line. Such repeated opening and closing of the high pressure relief valve causes the cutter bar to chatter and thereby signal the operator to stop the justing the valve mechanism 64 or 8|.

It will thus be seen that the efllciency of operation will be safely maintained at a maximum in that the electric motor 9| for driving the chain cutter will continuously and safely operate at its full load capacity or any other predetermined setting, so that when easy cutting is encountered, the rate of feed is automatically increased, and when the cutting is hard the rate of feed is automatically reduced. Moreover, when no cutting is taking place and the driving motor 9| is running free or is not operating, the rate of feed for adjustment of the kerf cutter relative to the supporting framework, is automatically raised to a maximum. That is, if the current'to the motor 9| is low o is cut off during such adjustments of the kerf cutter, the spring IS] in Fig. 7 moves the valve I91 to the left, as viewed in Fig. 11, to permit the pipe 200 to be connected to the drainage pipe 20l, whereupon the spring 209 (Fig. 8), is free to move the piston 201 to such position that the volume control valve cylinder 2 l1 will be in its widest open position for maximum flow of the fluid pressure medium to the adjusting motors.

In Fig. 13 of the drawings I have shown a modification of the system of my invention and it is to be understood that except for changes indicated, this modified system follows the system above described and particularly the hydraulic system disclosed in Fig. 7 of the drawings. As

a general statement it may be said that in the modified system of Fig. 13 I have eliminated the volume control valve mechanism 203 entirely. In place of the hydraulic power operated mechanism 202 I have substituted hydraulic power operated mechanism 202, the piston rod N2 of which is directly and positively connected to an adjustable ring 44 of a variable volume pump 44 'which replaces the pump 44 of the system of Fig. 7. The pump 44 is of well known construction and may follow in general that illustrated in the patent to Floyd 0. De Millar, No. 2,057,089, for a Hydraulic road grader, dated October 13, 1936, except that in the pump 44 the volume is controlled by positive adjustment of the controllable ring 44!, while in the De Millar patent this ring is spring-biased to one position and is operated by a hydraulic plunger in the opposite direction.

Fundamentally the system of Fig. 13 operates the same as the system of Fig. 7. Specifically, they differ in this respect: In the system of Fig.

13 the pump 44 normally delivers hydraulic fluid under pressure at a rate in excess of that required to operate the feeding mechanism of the mining machine or any of the hydraulic jacks or motors which'are controlled by hydraulic fluid. The amount of hydraulic fluid, however, actually delivered to any hydraulic motor or jack in the system of Fig. 7 is automatically controlled by the by-pass mechanism 203 and is maintained at any predetermined but variable value as determined by the current in the motor 9! as aforedescribed. V

In the system of Fig. 13 all of the fluid output of the motor 44 is employed to do useful work and none of it is by-passed. For this rea-' son the system of Fig. 13 is more efllcient than that of Fig. 7. In the system of Fig. 13, instead of by-passing an amount of fluid from a pump which generates an excess amount, the volumet-.

ric output of the pump 44 is controlled directly by controlling the eccentricity oi the ring 44" in the manner well understood in the pump art and V which is fully described in the above-mentioned patent to De Millar, No. 2,057,089.

Obviously. those skilled inthe art may make various changes in the details and arrangement of parts without departing from the spirit and scope of the invention as defined by the claims hereto appended, and I therei'orewish not to be restricted to the precise construction herein disclosed.

Having thus described and shown an embodi-' ment of my invention, what I desire to secure by Letters Patent of the United States is:

1. In apparatus of the class described, the combination with a frame, of cutting mechanism mounted thereon, mechanism comprising an electric motor for driving said cutting mechanism, fluid-pressure motor means for feeding said cutting mechanism, a volumecontrol valve connected to said fluid-pressure motor means, a fluidpressure motor for actuating said volume control valve, a pilot valve for controlling said fluidpressure motor, and an electro-magnet in'circuit with said electric motor and. connected to said pilot valve to control the same in accordance with the current flowthrough said electric motor, the construction and arrangement being such that the said electric motor may be oper-. ated continuously at a predetermined full load capacity by reason of automatic regulation oi. the rate of feed of the cutting mechanism, such rate of feed being automatically increased when easy cutting is encountered in the mine vein and automatically decreased when the cutting is relatively hard, and when no cutting is taking place and the electric motor is not operating or running free the rate of feed for adjustment of the cutting mechanism is automatically increased to a maximum.

2. In apparatus 01 the class described, the combination with cutting mechanism, of an electric motor connected theretoto drive the same, by

spring to said pilot valve, spring-pressed abut-v ment mechanism associated with said lever and adapted to co-operate with said solenoid and spring to effect such operation ofsaid pilot valve as to cause said reciprocating hydraulic motor to control said volume control valve to vary the rate of feed of the cutting mechanism in accordance with the load thereby maintain such load at a predetermined value, and a hydraulic system of piping connections from the source of supply of pressure medium to secure such operation automatically.

3. In apparatus or the class described, the combination with cutting mechanism, or an electric motor connected thereto to drive the same, hydraulic motor means'for feeding said cutting mechanism, a volume controlvalve, a reciprocating hydraulic motor comprising a springpressed plunger connected to said valve to control the same, a pilot valve connectedto'said reciprocatmg hydraulic motor, anelectro-magnet on the electric motor and.

in circuit with said electric motor, means associated with said electro-magnet and said pilot valve to effect operation of the latter when current through said electric motor and said electro- I magnet varies due to variations of load on said electric motor, and a hydraulic system for the said valves and said hydraulic motors to enable increase of current through said electro-magnet to operate the pilot valve to direct hydraulic pressure to said reciprocating motor tocause the latter to partially close said volume control valve to reduce the flow of pressure medium to said feeding hydraulic motor means and therebyreduce the rate of feed of the cutting mechanism to prevent loading said motor beyond a predetermined limit.

4. In apparatus of the class described. the combination with cutting mechanism, of an electric motor connected thereto to drive the same, hydraulic motor means for feeding said cutting mechanism, hydraulic means comprising a pilot valve for controlling the rate of feed effected by said hydraulic motor feeding means, a solenoid in circuit with said electric motor, a plunger in said solenoid, a spring acting on said plunger'to retract the same when said solenoid is de-energized, a pivoted lever connecting said plunger and said pilot valve, limit stops on opposite sides of said lever set in accordance with the limits of said pilot valve, spring-pressed buffer devices on opposite sides of said lever in positions to be engaged by said lever before said limit stops are reached, means for adjusting the resistances offered by said buffer devices to movements of said lever by said spring and said solenoid acting on said plunger against the action of said spring, and a hydraulic system for said hydraulic motor and said hydraulic means to enable the latter to effect regulation of feed in accordance with variations of current flow through said solenoid due to variations of load on said electric motor and thereby maintain a substantially uniform load on the said electric motor.

5. In apparatus of the class described, the combination with cutting mechanism, of an electric motor for driving said cutting mechanism, hydraulic means for feeding said cutting mechanism, a hydraulic system including mechanism for supplying hydraulic fluid to said hydraulic feeding means at a controllable rate including an adjustable member, mechanism operated as determined by the position of said adjustable memher for continuously maintaining a substantially constant rate of hydraulic fluid flow to said hydraulic feeding means different for each of a plurality of operating positions of adjustment of said adjustable member, and means responsive to the load on said electric motor for adjusting said adjustable member to maintain said load within a predetermined range, said means being operable to increase the feed rate of said cutting mechanism when the load on said electric motor falls substantially below its rated value and to decrease said feed rate when said load goes substantially above said rated value.

6. In apparatus of the class described, the combination with cutting mechanism, of an electric motor for driving said cutting mechanism, hy-

draulic means for feeding said cutting mechanism, a hydraulic system including mechanism for supplying hydraulic fluid to said hydraulic feeding means at a controllable rate including an adjustable member, mechanism operated as determined by the position of said adjustable member for continuously maintaining a substantially constant rate of hydraulic fluid flow to said hydraulic feeding means different for each of a plurality of operating positions of adjustment of said adjustable member, said mechanism including a by-pass for part of said hydraulic fluid, and means responsive to the load on said electric motor for adjusting said adjustable member to maintain said load within a predetermined range, said means being operable to increase the feed rate of said cutting mechanism when the load on said electric motor falls substantially below its rated value and to decrease said feed rate when said load goes substantially above said rated value.

'7. In apparatus of the class described, the combination with-cutting mechanism, of an electric motor for driving said cutting mechanism, hydraulic means for feeding said cutting mechanism, a hydraulic system including mechanism for supplying hydraulic fluid to said hydraulic feeding means 'at a controllable rate including a variable output pump having means for varying its volumetric output comprising an adjustable member, mechanism operated as determined by the position of said adjustable member for continuously maintaining a substantially constant rate of hydraulic fluid flow to said hydraulic feeding means different for each of a plurality of operating positions of adjustment of said adjustable member, and means responsive to the load on said electric motor for adjusting saidadjustable member to maintain said load within a predetermined range, said means being operable to increase the feed rate of said cutting mechanism when the load on said electric motor fallssubstantially below its rated value and to decrease said feed rate when said load goes substantially above said rated value.

8. In a mining machine, the combination with cutting mechanism, of an electric motor for driving said cutting mechanism, hydraulic mechanism for feeding said cutting mechanism, a hydraulic system for supplying fluid under pressure to said hydraulic mechanism, a variable output pump in said hydraulic system, adjustable means operable on said pump and constructed and arranged to have a plurality ofpositions in which the fluid delivery to said hydraulic mechanism .is different for each position, and means responsive to the current flow in said electric motor for 'operating said adjustable means to adjust automatically therate of feed of said cutting mechanism to prevent overloading of said electric motor, while maintaining it in operation substantially at its rated capacity, said means beingoperable to increase the feed rate of said cutting mechanism when the load on said electricmotor falls substantially below its rated value and to decrease said feed rate when said load goes substantially above said rated value.

9. In a mining machine, the combination with cutting mechanism, of an electric motor for driving said cutting mechanism, hydraulic mechanism for feeding said cutting mechanism, a hydraulic system for supplying fluid under pressure to said hydraulic mechanism, a, pump in said hydraulic system, adjustable means constructed and arranged to have a plurality of positions in which the fluid delivery to said hydraulic mechanism is different for each position, and means responsive to the current flow in said electric motor for operating said adjustable means to adjust automatically the rate. of feed of said cutting mechanism to prevent overloading of said electric ume hydraulic pump,

motor, whilemaintaining it in operationsubstantially at its-rated capacity. a a

' lllpIna mining machine, the combination-with cuttingmechanism, of an electric motorfor driv- :ing said cutting, mechanism, hydraulic mechanism for feeding said cutting'mechanism, avolume-control valve inthe supply line connected to said hydraulic-mechanisrmmeans comprising an automatic valve "for byepa-ssinga portionofthe hydraulic pressure medium-before reaehing said volume control valve, hydraulic mechanism for operating said volume control valve, and means operative in response to current flow-in said electric motor for controlling said last-named hydraulic mechanism, the "construction and armangementbeingsuchthat the-feed rate of the hydraulic feeding'mechanism iscontrolled by the current flow in said'electric motor to prevent overloading the motor but eflecting *operation thereof at a predetermined maximum capacity. 1 '11. In amining machinethecombination with cutting mechanism, of-an electricimotor for drivingsaid cutting mechanism, hydraulic mechanism for feeding said cutting mechanism,;a volume control valve in thesupply line connectedto 1 said hydraulic feeding mechanism, means for effecting by-passing a portion of the hydraulic pressure medium from said'volume control valve,

a hydraulic motor'for operating said-voiumecon- .trol valve, a pilot valve for controllingsaid: hydraulic motor, andv means comprising an electromagnetln circuit with said electric motor for operating 'saidpilotvalve, the construction and arrangement being such that the feed rate of the cutting mechanism is automatically) regulated 'to 'keep'theelectric motor inoperatio'n at maximum capacity without overloading.

12."' Ina mining machine, the combination with cutting mechanism, of an electric motor for drivin'g said-cutting mechanlsm,hydraullc means for 'iee'ding' sai'd cutting mechanism, a constant vola volume control valve in asupply line-connecting said pump to said hydraulic'feedingmeanaa variable by-pass for the ydraulic fluid from said {volume control valve, hydrauli'cmeans for controlling said'volume control valve, means dependent upon the setting of said volume control valve forzautomatically con trolling said by+pass and thereby regulate the volume of liquid nowing tosaid hydraulic 'feeding means, and meansresp'dnsive to current flow in said electric'motor to'efiect automatic operationof saidhydraulic mean'sforcontrolling said volumegcontrol valve tovary the rate cfieed or the cutting mechanism load on the electriomotor,-the rate'orfeedbeing slowed downwhen-the load onthe-'electrie m'otor isincreased above its rated value and the rate of feed being increased when the loadonthe electric motor is decreased below its-ratedvaluex- 13. In a mining machine, the combination with a supporting frame, of cutting mechanism mounted thereon, means comprising an electric motor fordriving' said cutting mechanism, fluidpressurefmotor means for feeding said cutting mechanism, a volume control valve connected to said fluid-pressure motor means, fluid-pressure motor means for operating said volume control 'valve, 'mea'ns for automatically 'by-passing variable portions of the fluid pressure medium from 'the volume *controlvalve to efiect variations in feeding rate of the cutting mechanism, and

means comprising an electr c-magnet in circuit with "said electric motor and connected tosaid last-named"fiuid 'pressure motor means tosecure maccordan'ce' with the with the load on said electric fluid in excess of that operationofsaid volume control valve and said by-passing meam; to enact: regulatiomor-the vol-- ume of :fiuid pressure medium flowing to said fluid-pressure motor feeding means in accordance motor.

14. In amining'machine, the combination with cutting mechanism, of "hydraulic feedingmeans for said cutting mechanism, an electric motor connected to said cutting mechanism to drivethe same, a hydraulic pump having a normal operating output of hydraulic fluidin-excessof that usable by said hydraulic feeding-means during nor-- mal operation of-the machine, means comprising a volume control valve for conducting I hydraulic fluid from said pump to "said hydraultcifeeding means, means comprising another valve for bypassing -fiuid from the 1 pump before reaching ,said volume control valve, said by-pass valveaoting automatically to by-pass a portion-of the-hy- -draulic fluid substantially continuously during normal operation of said hydraulic feeding means, and means', operative in response tn the current flow to said electric-motor to actuate'said volume control valve to effect said operation of ,said by-pass valve, the volume of fiuidflowing-to said-hydraulicfeeding means beingthus regulatedin-accordance with the load on-the :notor,-the feed of-the cutting mechanism being slowed down when the'loado the-motor increases above its rated-value and-vice ver 15. In a mining machine-the combination with cutting. mechanism, of hydraulic'means forfeedingsaid cutting mechanism; I an electric motor connectedto said cutting mechanism to drive the same, meanscomprisinga volume controi valve and a supply conduit-for directinghydraulic fluid under pressure to said hydraulic feeding means, .a hydraulic pump having a normal-operating out.- put of hydraulicfluid in excess of i that usable '-by said hydraulic feeding means during normaloperation of themachine, saidpumpbeing connected-to saidsupply-conduit, pumoby-pass means comprising a valve controlling a by+pass-conduit leading from the supply conduit near the volume control valveto the-return side'of thepummsaid pump by-passmeans during normal operation of the machine serving tocontinuously by-pass a portion of the-hydraulic fluid :from the volume control'valve to thereturn side of means operative in response to current flow to said electric motor for setting said volume control valve tocontroi the extent of -movementof said bypass valve andtherebyregulate the volume of .by-passed hydraulicfluld.

16. In apparatus ofthe class described,-the

combination with working mechanism, of an electric motor for driving said working mechanism, hydraulickfeeding means for feeding said working mechanismto its work, a hydraulic pump having -a normal operating output of hydraulic usable by saidhydraulic feeding means duringmormal operation '01 the apparatus, a supply conduit between said pump and said-hydraulic feeding means, a. volume control valve having anl'adjustable siz s'passageway in said supply conduit, means re'sponsive to the electric motor for adjusting I valve to-vary the effective size ofsaid-passageway, apump by-pass for the excesshydraulicfluid from the supply conduit'on the pump side of, the volume control valve,='and a valve for controlling said by-pass-inaccordance with the'adjustedposition of the' volume control valve in the supplyconduit.

17. In apparatus of the class described, the

the'pump, and

combination with working mechanism, of an electric motor connected thereto to drive the same, hydraulic feeding means for feeding said working mechanism to its work, a hydraulic pump having a normal operating output of hydraulic fluid in excess of that usable by said hydraulic feeding means during normal operation of said apparatus, a supply conduit between said pump and said hydraulic feeding means, a volume control valve having an adjustable size passageway in said supply conduit, power-operated means for adjusting said volume control valve to vary the effective size of said passageway and hold said valve in adjusted position, means operative in response to current flow to said motor for adjusting said power-operated means whenever said current varies a predetermined amount from a desired value, a by-pass for the excess hydraulic fluid leading from said supply conduit, and a valve for controlling said by-pass in accordance with the adjustment of said size passageway in said supply conduit.

18. In apparatus of the class described, the combination with working mechanism, of an electric motor connected thereto to drive the same, hydraulic feeding means for feeding said working mechanism to the material to be worked upon, mechanism for supplying hydraulic fluid to said feeding means at a controllable rate, said mechanism comprising means including by-pass controlling means operating continuously to maintain said rate of hydraulic fluid flow at a predetermined value for each position of adjustment of an adjustable member thereof independently of the pressure of the hydraulic fluid, and means responsive to the current flow in said electric motor when it reaches a predetermined value for adjusting said adjustable member to adjust the value at which said rate of hydraulic fluid flow is predetermined to prevent overloading of said motor.

19. In apparatus of the class described, the combination with working mechanism, of an electric motor connected thereto to drive the same, hydraulic feeding means for feeding said working mechanism to the material to be worked upon, mechanism for supplying hydraulic fluid to said feeding means at a controllable rate, said mechanism comprising means operating continuously to maintain said rate of hydraulic fluid flow at a predetermined value for each position of adjustment of an adjustable member thereof independently of the pressure of the hydraulic fluid, and means responsive to the current flow in said electric motor when it reaches the rated value of said motor for adjusting said adjustable member to adjust the value at which said rate of hydraulic fluid flow is predetermined to prevent overloading of said motor, and also responsive to a reduction in the current flow below the rated value of said motor for adjusting said adjustable member to prevent underloading of said motor.

20. In apparatus of the class described, the combination with cutting mechanism, of hydraulic motor means for feeding said cutting mechanism, an electric motor for driving said cutting mechanism, a pump having an output in excess of the normal fluid consumption of said hydraulic motor means, conduit means for delivering hydraulic fluid from said pump to said hydraulic motor means, a fluid by-pass control valve in said conduit means constructed normally to by-pass a portion of said hydraulic fluid during operation of said pump and hydraulic motor means, and mechanism operable by variations of the current flow to said motor to control said by-pass valve to increase the fluid by-passed whenever said electric motor is over-loaded and to decrease the fluid by-passed whenever said electric motor is operating below its rated load whereby said electric motor is automatically maintained in operation substantially at its full rated load.

21. In apparatus, of the class described, the combination with cutting mechanism, of hydraulic motor means for feeding said cutting mechanism, an electric motor for driving said cutting mechanism, a pump, conduit means for delivering hydraulic fluid from said pump to said hydraulic motor means, and mechanism operable by variations of the current flow to said motor to control the rate of flow of hydraulic fluid to said hydraulic motor means to decrease said fluid flow whenever said electric motor is over-loaded and to increase said fluid flow whenever said electric motor is operating below its rated load whereby said electric motor is automatically maintained in operation substantially at its full rated load.

ROBERT K. JEFFREY.

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