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Publication numberUS2322740 A
Publication typeGrant
Publication dateJun 22, 1943
Filing dateJun 5, 1940
Priority dateJun 5, 1940
Publication numberUS 2322740 A, US 2322740A, US-A-2322740, US2322740 A, US2322740A
InventorsFelt Adolph E, Vanderzee Harry H
Original AssigneeSullivan Machinery Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Hydraulically operated apparatus
US 2322740 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

June 22, 1943. H. H. vANDERzEE ETAL IIYDRAULIGLLY OPERATED APPARATUS Filed June. 5, 1940 2 Sheets-Sheet 1 Eig.

. s in- 8 June 22, 1943.

H. H. vxnuaslzzlala: ETAL HYDRAULICALLY OPERATED APPARATUS 2 sheets-sheet 2 y Filed June 5, 1940 'uit Patented June 22, 1943 UNITED STATES yPrrrENT OFFICE 2,322,740 HYDRAULICALLY oPERA'rEn APPARATUS Harry H. Vanderzee, Claremont, N. H.. and Adolph E. Felt, Marquette, Mich., assignors to Sullivan Machinery Company, a corporation of Massachusetts Application June s, 194'0, serial Nmsssso `(el. fio-52) 8 Claims.

improved hydraulically operated apparatus. An-

other object is to provide an improved hydraulic fluid system having improved means for controlling the supply of fluid under pressure to the various hydraulically operated devices. A further object is to provide an improved multiple valve means for controlling the flow of fluid under pressure to the various hydraulically operated devices. Still another object is to provide an improved hydraulic fluid system embodying an improved pump arrangement. A further object is to provide an improved dual capacity pump arrangement embodying a pump section of small capacity and a pump section of large capacity, the pump of small capacity normally maintaining the required pressure in the system when a small volume of fluid is required, and the pump of large capacity supplying a greater volume of fluid to the system when rapid operation is desired, the

presence of the small capacity pump and the capacity to by-pass the large capacity pump eliminating excessive generation of heat in the fluid system, due to by-passing of large quantities of fluid past a loaded relief valve, when only a small volumelof fluid is required. Still another object is to provide an improved control valve means for maintaining at least a predetermined minimum pressure on the operating pistons during operation of a hydraulically operated device. thereby to preclude unintended release of the device. These and other objects and advantages of the invention will, however, hereinafter more fully appear.

In the accompanying drawings there are shownA L for purposes of illustration one form and a modiiication which the invention vmay assume in practice.

tially on line 2-2 of Fig. 1.

Fig. 3 is a cross sectional View taken substantially on line 3-3 lof Fig. l.

Fig. 4 is a cross sectional View taken substantially on line 4--4 of Fig. l.

Fig. 5 is a diagrammatic view illustrating the improved hydraulic fluid system.-

Fig. 6 shows a modified form of hydraulic fluid system. l

In this illustrative form of the invention the improved hydraulic fluid system is shown asso ciated with a plurality of hydraulically operated devices generally designated I, 2, 3 and 4 respectively, which may assume various forms.

By way of example, but -without limitation thereto, these hydraulically operated devices may be embodied in a rotary drilling apparatus of the oil well type, and the device I constitutes a drill rod feeding mechanism and the device 2 a drill rod chuck operating mechanism. The device 3 i-n such a system might be provi-:led to effect tilt. ing of the derrick mast of the drilling apparatus, while the device 4 might then constitute a transfer means for shifting the feeding mechanism. z

laterally relative to the drill hole to clearthe latter.` Such a drilling apparatus might be of the same general type as that disclosed in a copending application to H. H. Vanderzee, Serial No. 275,235, filed May 23, 1939 now Patent No. 2,309,999, granted Feb. 2, 1943.

The device I is shown as comprising a pair ofparallel cylinders 5 (for example, feed cylinders, in a drilling apparatus) containing reciprocable operating pistonst, while the device 2.

(for example, a chuck operating device in a drilling apparatus) includes parallel cylinders V'I containing Areciprocable operating pistons 8. The device 3 (for example, a mast tilting device in a drilling apparatus) includes parallel cylinders 9 containing reciprocable operating pistons I0 while the device 4 (for example, a transfer device in a drilling apparatus) includes a cylinder II,conk

taining a reciprocable operating'piston I2. The various hydraulically operated devices are reversible and their operating pistons are subjectable to working pressure on their opposite sides so that they may be moved by power in either direction. The structure outlined above is shown merely for purposes ofillustraiion and it will be evident Ithat the improved hydraulic system may be associated with the hydraulically'operated devices of apparatus of a wide variety of types.

-The improved hydraulic fluid system comprises a pump I3, preferably of the dual capacity type, embodying a pump section I4 having a substantially greater capacity than the other pump section I5. This pump may consist of two distinct pumping units coupled together, one pump unit being of larger capacity than the other. 'I'his pump is arranged so that the small capacity side normally maintains the required pressure in the system when a small volume of fluid is required,

thereby eliminating an excessive heat generation in the liquid due to circulating large quantitiesv and I1, respectively, to a liquid supply tank I8.-

A valve box I9 has horizontal valve bores 20, 2|,

.22, 23 and 24 respectively containing slide valves 25, 26, 21, 28 and 29.- The inner ends of the valves 25, 26 and 21 are tapered in the manner shown, thereby to relieve the hammering which occurs in valves of this type, as is well known. 'I'he valve box comprises a plurality of sections held together by tie rods 30 (Fig. 4) and `each containing a valve bore, the valve box sections having gaskets interposed therebetween to prevent leakage. charge manifold 3| is secured to the valve box sections, at one end thereof, and has a discharge. chamber 32 with which the valve bores communicate and which is connected by a discharge conduit 33 back to the tank I8. posite ends of the valve box sections and closing the valve bores 20, 2|, 22 and 23 are heads 34 having packed bur es through which the valve stems 35 extend, and these heads may each carry a spri-ng-pressed plunger lock 36 for locking the valves in one position. Secured to the right hand valve bxsection in Fig. 1 and closing the bore 24 is a head 31 having a packed bore through which the valve stem 38 extends. Each valve stem has a manual operating handle. side of the pump is connected by a conduit 39 to a chamber 40 in the right hand section of the A dis- Secured to the op- The large capacity valve box, while the small capacity side of the l pump is connected by a conduit 4I to a chamber 42 in the next adjacent valve box. 'I'he several slide valves are hollow and their interiors communicate directly with the discharge chamber 32 and through ports 43 with the ends of their respective valve bores remote from the discharge chamber. tical and respectively control the flow of liquid to the cylinders 9, the cylinder and the cylinders lthe valve 28 and communicate with the groove 46,

as shown in Fig. 1. The valve 29 has relatively wide annular grooves 49 and 50 and a narrow intermediate groove 5 I, the latter communicating through ports 52 with the valve interior. Formed in the walls of the valve .bore 24 are annular grooves 53, 54, 55, 56 and 51, and the grooves 54 and 56 communicate directly with the chamber 48. For yieldingly urging the control valve 29 for the operating pistons 8 into and holding the valve in the position illustrated, there is seated on an annular shoulder 58, surrounding the valve` bore 24, a washer 59, the latter having a central opening through which the valve stem extends. This washer is held against this sloulder by a coil spring 60 interposed between the washer and a washer 6| engaging a shoulder on the valve stem and also adapted to engage the inner end wall of the head 31. It will thus be seen that irrespective of the position of the valve The three valves 25, 26, 21 are iden- 29 inwardly or outwardly from the position shown in Fig. 1, the valve, when released, will automatically be returned to the position shown by the coil spring 68. Formed in the walls of the valve bore 23 are three annular grooves 62, 53 and 64,-the rst communicating through a passage 65 with the groove 53 and the two latter grooves communicating directly with the chamber 42. Formed lin the walls of the valve bore 22 are three annular grooves 66, 61 and 68, and the valve bores 20 and 2| have similar sets of grooves 69, 10, 1| and 12, 13, 14, respectively. The grooves 61, 13 and 10 are connected by different parts of a passage 15 with one another and with the chamber 42. The grooves 55 and 51 of the valve bore 24 are connected by conduits 16 and 11, respectively, to the upper and lower endsof the cylinders 1 containing the operating pistons 8. discharge side of the small capacity pump, has embodied therein a restricter 18 in the form of a Venturi tube having a passage of minimum cross sectional area, and communicating with the conduit 4I'between this restricter 18 and the pump is a conduit 19 leading through a bleeder valve to the conduit 16. If the pressure in the conduit 16 for any reason drops below a predetermined minimum, the bleeder valve 80 will open automatically to admit liquid under pressure to the upper ends .of the cylinders 1 directly from the conduit 4I. The restricter 18 maintains at all times. in the portion of line 4| vleading from the small pump to it, a pressure wholly adequate to effect opening of the bleeder valve 80 and to supply the desired pressure to act on the operating pistons 8, and the restricter will be noted to be necessary because the small pump may be bypassed by the control. "alve 28. Also the restricter avoids all except the inherent friction energy losses when the pressure in the line 4| exceeds the minimum established by the restricter. The bleeder valve 80`is of the spring-loaded type and of such construction as to admit liquid under pressure to the operating pistons 8 when the pre'ssure on these pistons drops below a certain predetermined value, but does not permit flow inthe opposite direction. When self-locking operating devices are .provided for the device 2 it is found that, the restricter and bleeder valve may be eliminated. The groove 66 of the valve bore 22 is connected by a conduit 8| to the lower ends of the cylinders 5, while a conduit 82 connects the valve bore groove 68 with the upper ends of the cylinders 5. The groove 12 of the valve bore 2| is connected by a conduit 83 to one end of the cylinder I I, while the valve bore groove 14 is con-` nected by a conduit 84' to the opposite end of this cylinder. 'I'he groove 69 of the valve bore.. 20 is connected by a conduit 85.to branch con-j duits 86 leading to the upper ends of the cylinders 9, while the valve bore groove 1I is connected through a conduit 81 and branch conduits 88 to the lower ends of these cylinders, these latter conduits having check valves 89, provided with restricted by-pass ports, embodied therein, so that an excessively rapid movement of the operating pistons I0 can be prevented." The conduits 39 and 4| are connected, by the opposite halves of a conduit 98, through check valves 9|, with a conduit 92 leading to the return conduit 33. Thus I each can have uid pass to the return conduit, but not to the other. The conduit 92 has embodi'ed therein a relief valve 93 loaded so as to maintain the desiredpressure.

The conduit 4|, leading from the.

. bythe higher pressure is not desirable.

9i in the conduit 90 have been replaced by relief valves 94, which act as check valves also, and the relief valve 93 in the conduit 92 is omitted. When a single relief valve 94 is employed, it is necessary for the operator to adjust the pressure setting during lifting movement of the pistons of the operating cylinders 9, since a higher pressure isnecessary in the device disclosed during such lifting movement.

I0 are in their raised position, the relief valve may be reset to obtain a lower maximum pressure in the hydraulic system during normal operation of the apparatus. However, the arrangement embodying the two relief valves is preferable, since resetting of the relief valve after it has been set at the proper predetermined pressure is unnecessary, thereby removing the possibility of the operators failing to reset the relief valve When the operating pistonsl lng the smaller pumps discharge.

after operating the cylinders 9 to eiect raising of the pistons I8. Such failure of the resetting of the relief valve results in a too high pressure in the hydraulic fluid system for normal operation of the apparatus.- In actual practice, when two relief valves are employed, the relief valve of the large pump is set at a pressure substantially lower than the pressure setting of the relief valve for the small pump, since operation of the pistons 8 The relief valve for the small pump is set at' a higher pressure, since such higher pressure is required to effect raising of the operating pistons I0. The

valve 88 can then be caused to limit the pressure passing through line 19 to the cylinders I. The pressure used for effecting movement of the pistons 6 is, however, determinable selectively by the positioning of the by-pass valve 28, and by the relief valve settings. Of course, when both pumps are discharged to the cylinders 5, the maximum pressure available in the hydraulic fluid system is the pressure settingof the relief valve for the large pump, as both pumps may discharge past this relief valve., Thus, with'the connections of Fig. 6, and the valve positions of Fig. 1, the maximum pressure at any of the hydraulically operated devices I, 3 and 4 would be determined by the by-pass valve between conduits 39 and 92'.

' If valve 28 be moved part way downwardlyin Fig.

l, just enough to vent passage 65, the pressure for the devices mentioned would be determined bythe by-pass valve between conduits 4I and 92. If valve28 were moved downwardly to establish communication with groove 64 cf grooves 48, or

of these grooves 48 and also grooves 46, then control of pressure exclusively by the position of the by-pass valve may be obtained, in the sense that pressures below the limiting values set by the relief valve means can be secured.

, In Fig. 1 both pump discharges are shown connected to the pressure supply passage so that the desired volume of liquid is obtained by the combined discharges of both'pumps, and when the by-pass valve 28 is moved'axially from the position shown in that ligure the discharge passage 65 leading from the large pump is connected to the discharge chamber 32 past the end of valve 28, so that at that time a relatively small volume of liquid is supplied from the small pump to the hydraulic system. The quantity supplied can be very closely regulated by moving the valve 28 (downwardly i-n Fig. 1) to a position in which venting of chamber 42 to a desired degree through grooves 48 and 46 and ports 41 and the interior of the valve Will be possible. Thus with a rereverse flow.

duced supply andwith individual control of delivered quantities a very effective control of operf lower ends of these cylinders will continue to be vented through ports 43. Opposite movement of valve 29 will connect passage 16 with groove 5I land ports 52.

From the foregoing, it will be evident that 'the operating cylinders 9, the operating cylinder II,

and the device I may be operated under the control of the valves 25, 26 and 21, respectively and the volume of liquid flowing through thesystem may be controlled bythe by-pass valve 29 first by determining whether the large pump discharge is to be by-passed and second by variably by-pass- By the provision of the control valve 29 the entire output of the large pump I4 may be made available at relief valve pressure to effect operation of the cylinders 1 to effect opposite movement of the operating pistons il, and by the provision of the restricter 18 and bleeder valve 80 a predetermined at least relatively constant pressure may be maintained on the pistons 3. when the passage 16 is cut off from communication with the venting means and also with the supply connection 39, thereby preventing inadvertent release of the device operated thereby. The control valve 29, as well asthe other valves, is independently operable so that the cylinders 1 may be controlled at will regardless of the positions of the other valves. By the provision of the dual pump arrangement, a relatively small volume of liquid may be maintained under pressure in the fluid system during normal operation of the apparatus and a relatively large volume of liquid under pressure may be supplied to the system when rapid operation is desired. When the load on the operating pistons 6 of the device I becomes excessive, both pump-discharges may be by-passed by means of the by-pass valve 28 and the rate of piston movement regulated by metering the flow of liquid from the lower ends of the cylinder 5 beneath` the pistons 6 by means of the valve 21.

Under certain conditions, the small pump may supply liquid under pressure to the upper ends of the cylinders 5 above the pistons 6, and, whether the pressure therein be determined by regulating the by-pass or by completely closing the by-pass and forcing the liquid past the relief valve, the rate of ,feed may be governed by metering the flow of'liquid from beneath the pistons. The presence of the small capacity pump I5, together with the capacity to'fby-pass the large pump discharge, eliminates the excessive generation of heat from the fluid system which occurs when alarge volume of liquid is forced past a loaded relief valve for any substantial length of time. from the conduits 39 and 4I to the return conduit 33 and prevent reverse flow, and, as above described, the relief valve '93 .is setto open automatically to relieve an excessive pressure in the system. The check valves 89 in the conduits 88 leading'to the operating cylinders 9 permit liquidflow to the cylinders, but, through the restricted by-pass ports,

It lwill be evident that by forming l the valve box in a plurality of sections and securing the sections together by tie bolts, the valve box structure is simplified. When the control The check valves 9I permit ow of liquid automatically retard sensitive fluid flow regulation is possible.

of its opposite positions, it is returned automatically into its central position by the coil spring 60 when its control handle is released by the operator. By the provision of the metering slots 48 in the by-pass valve 28, an extremely In the modied hydraulic iiuid system, the relief valves la described one form and a modification which the.

inventionmay assume in practice, it will be understood that this form and modiilcation of the same are shown for purposes of illustration and that the invention may be further modied and embodied in various other forms without departing from its spirit or the scope of the appended claims. f

What we claim as new and desire to secure by Letters Patents is:

1. In a hydraulically operated apparatus, the combination with a hydraulically operated mean's actuated on the supply of liquid to one end to move in one direction and on the supply of liquid to its Aopposite end to move in another direction, of means for. supplying liquid under pressure to said hydraulically operated means comprising pumping means having a small capacity discharge and a large capacity discharge,

means for supplying liquid from said low capacity discharge to one end of said hydraulically oper.- ated means including means governed automatically by the pressure in said end for establishing communication between the llatter and said low capacity discharge whenever the pressure in saidend is below a predetermined value,

and valve means comprising a valve box having a bore and a slide valve receivable in said bore for controlling said large capacity pump discharge whereby the latter may be connected to the same end of said hydraulically operated means or the large capacity discharge may be cut off from said end while the flow of liquid .from the low capacity discharge to said end remains unaiected.

v2.' In combination, a hydraulically operated device, a pump of small vdischarge capacity, a pump of larger discharge capacity, a valve casing providing a bore, means forming a passage leading from the pump of larger discharge capacity and communicating with said valve casing bore at a point adjacent one end thereof, a connection from the pump of smaller discharge capacity communicating with said valve casing bore at i.

two points spaced from each other and said first- -past an end of said valve, and means for connecting said second and third connections to the hydraulically operated device at will.

3. In combination, reversible hydraulically operated means, a hydraulically operated mechanism, a plurality of pumps of diiIerent discharge volumes for supplying fluid to said hydraulically operated means and to said mechanism, a return line to said pumps, and controlling means for said hydraulically operated means and said mechanism for controlling fluid flow relative to them from said pumps including a valve casing having three bores therein, three valves reciprocable in said casing, one in each of said bores, iiuid supply conduits leading from said pumps to said casing, one of said iluid supply conduits having passages leading to two of said bores and another having communication with the third of said bores, passage means for connecting said last mentioned bore with one of the others, the valve in the third mentioned bore reciprocable therein to control said mechanism and the 'connection of the third mentioned bore with the one of the others to which said passage means leads from said third mentioned bore, the valve in the bore to which said last mentioned passage means leads controlling communication between that bore and said third mentioned bore and communication between each of said supply conduits and the return line to said pumps,

and the valve in the other of said bores controlling said hydraulically. operated means, and means for automatically establishing communication .between said pump which has a smaller discharge volume and one end of said hydrau-l lically operated mechanism, whenever the pressure in said end is below a predetermined value.

4. In combination, a valve casing having a plurality of substantially parallel bores therein, a chamber at one en d of said casing into which said bores severally openfa plurality of passages for the supply of iluid opening into one of said bores at points spaced along its length, fluid delivery and return passages leading from said one bore at points at opposite sides of one of said first mentioned passages, and` a passage extending from said one bore to the next bore at a point in the latter near the communication thereof with said chamber, a valve in said one bore having grooves in its periphery for selectively connecting one of said supply passages with the passages at its opposite sides and connecting the other of said supply passages with the passage leading to said next bore, said valve having means thereon for connecting the passages at the opposite sides of the rst supply passage alternatively to said chamber, a plurality of passages for the supply of fluid opening into'said next bore, a valve in said next bore having means formed thereon for controlling communication of said passage extending between the bores with said chamber, and for establishing and interrupting communication between said two bores and for connecting one of said supply passages opening into said next bore with said chamber, means for connecting one of said last mentioned supply passages with a third bore, fluid delivery and return passages communicating with said third bore at a plurality of vpoints therein, and valve means in said third Vbore for establishing communication selectively between said last mentioned connecting means and one or another of said last mentioned iluid delivery and return passages, and for connecting the said conducting means with said chamber.

" 5. In a hydraulic control mechanism, in combination, a hydraulic pump of high capacity, a hydraulic pump of low capacity, said pumps having a common intake, a hydraulically operl ated device actuated on the supply of a liquid to one end to move inone direction and on the supply of liquid to its opposite end to move in another direction, means for supplying liquid from said pump of low capacity to one end of said hydraulically operated device including means for automatically establishing communication between said pump and said end whenever the pressure in the latter is below a predetermined value, and means including a manually operated valve for selectively connecting one end of said hydraulically operated device to said pump of high capacity while connecting its other end to the intake of said pumps.

6. In a hydraulic control mechanism, in cornbination, a hydraulic pump of high capacity, a hydraulic pumpf low capacity, a hydraulically operated, device moved in one direction on the supply of a liquid to one end while liquid is vented from its other end and moved in an opposite direction when the supply and venting of liquid relative to the ends of said hydraulically operated device are reversed, means for supplying liquid from said pump of low capacity to one end of said hydraulically operated device including means for automatically establishing communication between said pump and said end whenever the pressure in the latter is below a predetermined value, means for supplying liquid from said pump of high capacity selectively to the ends of said hydraulically operated device and simultaneously venting liquid from the end one reason for interconnecting said rst connection with one of the others through one of said valve grooves and movable to another position to connect said rst mentioned connection with said discharge line and to connect the third of said connections through the other groove also with said discharge line, said iirst connection being connected with said discharge line past an end of said valve, land means for connecting said second and third connections to the hydraulically operated device at will.

8. In combination, a valve casing having a plurality of bores therein, a chamber in said casing into which said bores severally open, a plurality of passages for the supply of fluid opening into one of said bores at points spaced along -its length, fluid delivery and return passages leading from said one bore at points at opposite sides of one of said first mentioned passages, and a passage extending from said one bore to the next bore at a point in the latter near the communication thereof with said chamber, a valve in said one bore having grooves in its periphery for selectively connecting' one of said supply passages with the passages at its opposite sides and connecting the other of said supply passages with the passage lea'ding to said next bore, said valve having means thereon for connecting the passages at the opposite sides of the of said device opposite to that connected to-said pump of high capacity, said last mentioned means including a manually operated valve movable to positions for connecting selectively the ends of said hydraulically operated device' to said pump of high capacity and to vent or for cutting off the ends of said device from said pump of high capacity and from vent.

'7. In combination, a hydraulically operable device, a pump of small discharge capacity, a pump of larger discharge capacity, a valve casing, means forming a passage leading from the pump of larger discharge capacity and communicating with said valve casing at a point adjacent one end thereof, a connection from the pump of smaller discharge capacity communicating with said valve casing at but two points spaced from each other and said first namedpoint of communication, a slide valve movable in said casing, a discharge line leading from said casing and connected to the intakes of said pumps, said slide valve having spaced grooves and movable into first supply ,passage alternatively -to said chamber, a plurality of passages for the supply of fluid opening into said next bore, a valve in said next bore having means formed thereon for controlling communication of said passage extending between the bores with said chamber, and for establishing and interrupting communication btween said two bores and for connecting Vone of said supply passages opening into said next bore with said chamber, means for connecting one of said last mentioned supply passages with a third bore. uid delivery and return passages communicating with said third bore at a plurality of points thereimand -valve means in said third bore forestablishing communication selectively between said last mentioned connecting means and one or another of said last mentioned Iiuid delivery and return passagespand for connecting the said last mentioned ui'd delivery and return passages means with said chamber.

HARRY H. VANDERzEEg ADOLPH E. FELT.

l CERTIFICATE oF coRREcTIoN. Patent No. 2,322,7LL0. l June 22, '191;5,

HARRY H. vANDERzEE, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, first column, line 14.0, for l'discharged" read --discharging; age 11 second column, line s' 68 and 69, claim l1., for "conducting means" read 1ast mentioned fluid delivery and return passages--g page 5, second column, line 1,-claim 7, for reason" readupositionn; line M9, c laim 8, strike out "means"; and that the said Letters Patent should be read with this correction therein that the same may conform to the record ofthe case in .the Patent Office.

Signedand s'ea1ed this and day of November, A. D. 1915.

Henry Van Arsdale (Seel) Acting Commissioner 'of Patent s.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3061028 *Dec 2, 1957Oct 30, 1962Brooks WalkerMotor vehicle lifting and traversing device
US3107694 *Apr 22, 1960Oct 22, 1963Aurora CorpPlural valve arrangements
US3112769 *Mar 24, 1960Dec 3, 1963Aurora CorpValve mechanism
US6018895 *Dec 4, 1996Feb 1, 2000Clark Equipment CompanyValve stack in a mini-excavator directing fluid under pressure from multiple pumps to actuable elements
US6029446 *Sep 25, 1997Feb 29, 2000Melroe CompanyMultifunction valve stack
Classifications
U.S. Classification60/429, 91/31, 60/421, 91/168, 137/884, 91/508, 60/427, 137/637, 91/452, 137/596.12
International ClassificationB23B47/00, E21B19/08, E21B19/00, B23B47/08
Cooperative ClassificationE21B19/08
European ClassificationE21B19/08