US2613906A - Hydraulic control valve - Google Patents

Description

Oct. 14, 1952 H. c. WEIMAR 2,613,906

HYDRAULIC CONTROL VALVE Filed May 25, 1948 2 SHEETS-SHEET 1 72 w '1 4 5; g 3 2% A; 7% #8, #6 n1 /6/% I 26 a Oct. 14, 1952 H. c. WEIMAR 2,613,906

HYDRAULIC CONTROL VALVE Filed May 25, 1948 2 SHEETSSHEET 2 5 4 .16 R 16 51 I 1 :1 J

L J Lvl 17 J7: .16 .19 1 9490 2 52 fig? Patented Oct. 14, 1952 HYDRAULIC CONTROL VALVE Hans C. 'Weimar, Providence, R. L, assig'nor to Brown and Sharpe Manufacturing Company, Providence lt. I., a corporation of Rhode Island Application May 25, 1948, Serial No. 29,042

8 Claims.

The present invention relates to an improved hydraulic control valve, and is herein disclosed in a preferred. form .as embodied in a peed con.- trol valve adapted for controlling the rate of movement of a machine tool support as, for example, a hydraulically actuated grinding machine wor'ksupporting table.

It is a principal object of the invention to pro vide a novel and improved control valve" of which theimovable'valve element is adapted for adjustment by substantially evenly spaced increments of movement over" a reasonable range from a closed toa fully opened position, and of which the throttle opening is arranged to be adjusted by said increments of movement from a closed to a fully opened position to provide a series of accurately determined very slow speeds of the driven support which may range, for example,

from one to several inches per minute, and thereafter a series of more widely spaced higher speeds as the valve element approaches its fully opened position,

It is a further object of the invention to providea novel and. improved control'valve of which the throttle opening is increased proportionately as the square of the distance moved by the'movablevalve element, which is simple and economical in construction, and adapted for easy manual adjustment for the: accurate control of. the rate of support movement.

lit is a further object of the invention to provide": asimple and eiiicient valve construction includlng means available ininitially adjusting the valve mechanism to accurately ascertain the starting position of the valve and to provide accurate calibration of. the valve particularly over the very slow speed range in accordance with asimple and effective method of adjustment hereinafter more fully set forth. 7

With the above: and other objects" in view as may hereinafter appear, a principal feature of the inventloneonsists in the provision or cylindrical valveand. sleeve elements which are inscrewthreaded. relation to one another so that a com.- bined rotational and axial movement of one element relative to the other is effected, and which are formed. with rectilinear apertures arranged to be moved diagonally into overlying: relation.

v 2 a a p in the sleeve element is formed by means of a transverse out of a depth extending nearly to: the axis of the sleeve and of a width preferably greater than required for full valve opening. The

cooperating rectangular opening in the valve member is formed by slabbing off half the diameter of the valve member at its inner end. The 5 efiective opening or aperture oftheyvalve in any position is determined by the amount of overlap of the semi-cylindrical edge of the slabbed-ofi portion of the valve member and a transverse edge of the slot in the sleeve member in one direction and the amount of overlap of two cooperating side edges of the respective valve and sleeve elements in the other direction. l

Another feature of the invention consists in the novel construction and arrangementof, the

valve assembly to facilitate an'jinitial accurate adjustment of thevalve mechanism including a rotatably adjustable nut into' which the valve stem is threaded for imparting-the desired r o,-'

tational andaxial movements to the valve memberto open and close the valve, In the illus-v trated construction, the nut element is circular in form, and is angularly adjustable by means of v asuitable pin wrench, being normally secured in adjusted position by means. of anoverlying axial movement of thevalve element, and the manuallyxoperable control knob; 2 :is.

end-view of the control knob and its associated. dial shown. in Fig. 1 looking from the-left; is a view similar to Fig. 2, but with the control knob removed. and portions of the underlying adjustable nut and associated clamp ring broken away'and' sectioned; Fig"; 4 is a sectional view taken 'onfthe line 44 of Fig. 1, showing the valve in its fully open position; Fig.- l5is a view similarto Fig; 4: showing the valve throttle and more particularly the side ports in intermediate or half-way position between fully opened'zandv shut-off position; Fig. dis a view similar to "accordance with the parabolic law.- The-controlvalve illustrated in the drawings ias embodying in a preferred form the several 3 Figs. 4 and 5, but with the valve shown in its fully closed position; Fig. 7 is a fragmentary developed view showing the relation of the valve stem and cylinder with the valve fully opened as shown in Fig. i; Fig. 8- is a developed view similar to Fig. 5, in which the valve stem has been turned half-way to its shut-off position; Fig. 9 is a developed View of the parts in the shut-off position shown specifically in Fig. 6; Fig. 10 is a view of the valve control mechanism looking from the left, but with the manually operable knob removed and a pair of gauging devicesapplied respectively. to the valve stem and rotatably adjustable nut preparatory for adjustment; Fig. ll is a sectional view looking 'fromthe right,

taken on the line H-ll of Fig. 10; Figs. 12 to V s 16 inclusive, are a series of developed diagram-a matic view showing successive positions of the relatively movable valve elements in positions taken during the process of adjusting the degreater than is required for the maximum throttle opening of the valve. A'cooperating port opening is formed in the inner right hand end of the valve member 12 in the form of a semi-cylindrical cutout in the end of the valve member. With the valve in the fully opened position shown, for example, in Fig. 1, liquid under pressure is admitted through the, inlet pipe 24 to the port 28, through the port 39' in the valve member, and thence outwardly to the right by way of the end of the valve sleeve Hi to the outlet pipe 26.

The valve member I2 is arranged to have imparted thereto a combined rotational and axial movement which has the effect of causing the rectangularly-shaped apertures provided by ports 28 and 30 to move diagonally into overlying relation attheir adjacent corners to open so that the vice; Figs. 17 to 21 inclusive, correspond respectively'with the positions of the valve elements shown'in Figs. 12 to 16; and Fig. 22 is a diagram illustr'atingthe manner in which the throttle opening of the valve and related rate of drive of thehydraulically driven support i increased in =feature's'g'of the invention, is particularly adapted and: is calibrated to control the rate of movement of: -a hydraulically-actuated grinding machine worksupportin'g table having-a range of operat- 'ing speeds fromgone inch per minute up to any desired maximum, which may for example be the ldl inches per minute indicated on the dial of Fig. '2. -In--actual operation, a close control of the'rate of'travel of the table is desirable at the lo'wer'spe'eds,-.while at the same time provision m'ust also'be made for a reasonable range of operating table speeds at much'higher feed rates. *Adifference of speed-amounting to an inch'per 'minute within theslow speed range extending from one to six inches of travel of the grinding machine table may be of considerable-conselqu'ence, for-example, in connection with wheel :truin'gl In carrying out the present invention, a simple and yet eiiicient valve mechanism ha been developed, inwhi'ch themovable valve element'is arranged to be shifted through approximately equalincrements ofdistance to successive'posi "tions of adjustment in order to providefora .sure is introduced intov the valve assembly by mean of an inlet duct. 24, ,passes' through a throttle'opening inthe,valve,-and is then dis charged-through an .outlet 26 connecting with theouter'end of thevalve sleeve'member Hl. Cooperatingports are formed in thevalve sleeve member l4 and valve member 12 which are rendered operative by. a combined rotational and axial movement of the-valve member I2. to control the amount of fluid passing through the valve.

I A-.-port.2 8 is'formed' inthe valve :sleeve 14 in the formof a transverse cut extending nearly to thetaxisoi the sleeve l 4, and of a width preferably size of the aperture or throttle opening will increase in proportion to the square of the distance moved by the valve element l2. Specifically, the area of throttle .openingincreases in accordance with the formula for a parabola x =ay where m is a unit ofdistance'through which the valve element 12 is moved orturned, y i thegarea of throttle opening, andv a is a constantiactor determined by the dimensions of the valve and the units chosen for x and .y'. For simplicity of illustration, the factor a.is taken as'unity in the graph Fig. 22. s i

The manner-in which the valve opensis illustrated in graph form iniFig. 22. Inthis figure, the values of :r and 11/ have been arbitrarily chosen. In the graph, the-r coordinate represents arbitrary units of. the angle of valve opening.. The-y coordinate represents arbitraryunits dash diagonally extending line B is the graph of a valve such as the ordinary needle .valvewhich opens in accordance with a straight line law, and is introduced solely for purposes of comparison. Fig. 22 demonstrates the advantage achieved by the improvedvalve disclosed which opens in accordance with the parabolic law. From the graph,it will readily be seen that the initial-increments of movement of the valve fromclosed position to open; will efiect a relatively small. increase in aperture and consequent table speed, whereas, as the valve continues its movement to open, increments ofrmovementof equal extent will produce much larger increases of aperture particularly adapted for adjustment of the valve inthe'high'speed range. v

Forucontro-lling the movement of the-valve member l2, there is provided an enlarged valve stem-34 which passes through an oversize apere ture 35 :in the wall 20 ofrthe machine frame, thence through an oversize' a'perture .38 inlanother .wall portion 48 of the machine frameand is formed with a screw --.thread 42 threaded through-a nut t4 secured-to the outer face of the wall 40. At its outer endpthe valve stem, 34; has i mountedthereon a manually operable, control knob 46' which is secured in position on the stembya set screw 48. -As shown insthe.;draw. ings, the nutv is formed with a circular outer edge having an annularfiange 50 against which mounted toextend outwardly from the face. of the clamping ring 52 projects into-an annular groove 60 formed in the under face of the manual controlknob 46 torpositively limit angular movement of the control knob and valve stem 34 therewith in either direction. I

Inorder to insure the accurate positioning of thevalve member 12 axially of the valve sleeve Ilirrespective of any looseness or wear which may exist between the. screw 42 and nut 44 elements, a helical take-up spring 64 isv coiled about the valve stem 34. between a washer 66 retained onthe valve stem 34, and a sleeve abutment 68 arranged to bear against. the left hand or outer face fv the wall of the casing. With this construction it is appreciated that an axial jogging of the control knob 46 and valve stem'34 against. the pressure of the spring 64 will have the-effect of momentarily changing the speed .of the: driven support. It is appreciated further that such an accidentaljogging which might tend to increase the feed rate would involve aserious hazard of overloading and-damage both to the machine and, to the work being operated upon. With the illustratedconstruction, the thrust of. the spring upon the valve stem 34 and control knob 46 is outward to open for the adjusted potary and harmless slowing of the driven support. In-ord-er to avoid any possible tendency ofthe take-up spring 64 or-its associated abutments 68 to become frictionally engaged against the wall 20, with. the result that torsional strains may beset up in the spring 64 tending to move the. valve stem 34 and associated parts rotation ally from adjusted position, the sleeve abutment 66 is keyed to turn with and to slide with relation toth valve stem 34 by means of a key 10 Y passing through a slot in the valve stem.

As illustrated, for example, in Figs. 1 and 2 of the drawings, the control knob 46 is formed to provide an indicator dialill having calibrated markings thereon to. cooperate with a relatively stationary'marker 12 carried on the nut clampingiifring- 52. With the. illustrated construction, the dial H is calibrated in terms of inches per minute ofv travel of a hydraulically-actuated grinding machine work supporting table. These calibrations includea group of very slow table speeds'from 1 to 6 inches per minue, and a group of. more rapidly increasing higher speeds ranging from 16 to 144 inches per minute. V V

. The manner in which the ports 28 and are moved with relation to one another to cause the throttle opening to be increased in proportion to: thesquare of the increment of movementz of the. valve stem will be readily. understood from an inspection of Figs. 4 to 6 showing the valve. respectively in its fully opened, partly opened and fully closed positions taken in connection with.

the diagrammatic developed. views of the parts. in the corresponding positions of Figs. 7, 8 and 9. Starting with the fully closed position of. Fig. 6,

itwill be seen that the valve member I2. is turned 7 5 so that the projecting semi-cylindrical end portion of the valve member designated at I4 is turned to fully blank off the-sleeve port 28 while at the same time the valve member has been moved inwardly, or to the right from'the position shown in Fig. 1, into its'sleeve M to such an extent. that the transverse edge surface I6 of the semi-cylindrical cutout has moved beyond the adjacent transverse edgesurfaoe 1B of the in-'- let port 28, so that the valve is entirely shut off. If the control knob 46 is now rotated in a counterclockwise direction, the combined rotational and axial movement thus imparted to'the valve member 12 causes the adjacent corners of. the two ports 28 and30 to movediagonally into overlapping relation withirelation to one another. Th -rotational orutransver'se movement of the valve member I 2 causes the two adj acent. vertical edges of the respective portsv to overlap, whereas the longitudinal component .of' valve movement causes thecooperating transverse edges 16 and 18 to overlap to produce the rectangular opening of Fig. 8, this opening being thereafter in.-

creased by continued. rotational movement ofzthe The valvemechanism above described has the advantage that it can be adjusted to operatepwith a highdegree of precision, particularly over the slowspeedirange of adjustment,.while'at the-same time the .valve parts are. of simple construction and are inexpensively produced without any necessityfor maintaining a high standard of precision in manufacture. .A feature of the inven-e tion which contributes in large. measure td-the' highlya'ccurate results obtained, consists in the means for adjustmentemployed. in'connection with'the' setting up of the valve mechanism; so that the exact point of blanking off of the throttle aperture is readily determined, and-an accurate scale of speed adjustments maybe obtained particularly over the slow speed range of .the' valve.

The combination of the cooperating. rectangular valve ports and the screw-threaded'bonnection for controlling therelative movement o f the valve and valve sleeve-elements has been fou'n'dfof advantage in that it automatically provides for-a slow rate of increase of valve aperture for 'the initial increments of relative movement from closed to open position of the valve, and thus per-'- mits the'use of substantial increments of movement to produce the very fine speed changes required at the. low speeds of support movement. In this connection also, the provision of the takeup spring 64 is of particular value toinsure the elimination of backlash in the screw thread and the consequent maintenance of a' high degree of accuracy in the critical. axial setting of the valve element. M t, A preferred and advantageousmethodfor er fecting the adjustment of the valve mechanism is illustrated and will bedescribe'd in connection with Figs. 10 to 21 inclusive of the drawings; as best shown in Figs. 10 and 11, for purposes of ad justment the hand knob 46 has been removed; a pin wrench ,84has been applied to the adjustable nut 44', and an adjusting dog 86 having a split clamping portion and clamping screw this secured to the valve stem 34 in place of the man-- ual control. knob 46. The dog is'provid'ed at its outer end with a pointer 90 havingaa wedge- 'in Figs; 13 and 18.

For convenience in (setting up the valve mechanism, a transverse screw driver slot 94 is formed in, the end of'the, valve, stem exactly parallel to the face of the semi-cylindrical cutout 30 formed inthe-yalve member 12. A'punch mark. 96 is formed in the end of the valve stem 34 at one side of the ,slot 94 and in the same relation thereto as :the semi-cylindrical segmentFM-left by the cutout 30 at the end of the .valve member 12..

The: several steps of the operationof adjusting the valve mechanism are briefly as follows: The adjusting dog 86 is mounted on the valve stem 34with the pointer 90 in position vertically above the valve, stem 34, and with the punch mark 96 also in line with the pointer 90 as shown, for'example, in Figs. 10, 11 and 17. The screws 54 on the nut clamping collar 52 are backed 01f just enough to permit the nut 44 to bev turned with the pin wrench 84. With. the hydraulic pressure on the system, the control support which may be assumed to be a grinding machine work supporting table, will either move indicating that the valve member I2 is retracted out of thev-alve sleeve l4 so far as to uncover the inlet port 28,

orthe table will be stopped, showing that the semi-cylindrical segment 14' is projected sufiiciently into the sleeve M to blank off the port 128. In either event, the nut 45 is rotated while the valve stem is held stationary in the position of Fig. 10. Assuming that the nut is provided with a right hand thread, a clockwiserotationzof 1 the nut will tend to open, and a counterclockwise step in the operation of adjustment is, while leaving the nut stationary, to rotate the valve stem by means of the dog 86 in a counterclockwise direction until the table starts. The blank: ing oiT point thus arrived at is the position shown The blanking off point as show in Fig. 18, is marked with a'pencil on the surface of, the clamping ring 52 in alignment with the pointer 90 of the. dog. As a third step in the operation, the valve stem 34 is rotated counterclockwise to the position shown in Figs. 14 and 19, that is, with the dog pointer directly beneath the valve stem, the nut 44 being held stationary. For this position of the parts, the valve is wide openand the table ismoved at a maximum speed governed by pump capacity. As a'fourth step in the operation, while holding the valve stemsta tionary, the nut 44 is turned counterclockwise un til the table just stops. This is theposition' shown in Figs. 15 and of the drawings. It will be noted that Figs. 13 and 18 show one preliminary blanking off position in which the cooperating longitudinal edges of the ports 28fand are about to overlap as the result of the rotational movement of the valve member 12,.while Figsr15 and 20 show another preliminary blanking oil position in which the adjacent transyersefedges of the ports 28 and 30 are about to 'movelinto overlapping position as the result "of relative axial movement of the valve'rnemberjlland'valve sleeve'l. V p

,From the position shown in Figs, 15 a nd 2 0 the valve stem and nut will now be rotatedin unison in a clockwise direction until the pointer on the dog 86 lines up with the pencil mark on the surface of the clamping ring 52. 'In orderto 8 assist'in this operation, the link 92 is moved on top of the handleof the pin wrench 84 and the two parts are held together by finger pressure during. the rotational movement to theposition,

ofFigsi 16 and 21. The valve mechanism is now in the position of adjustment. The clamping screwsxful are tightened to cause the clamping rin 52 to rigidly securethe nut 44 in adjusted position, and th dog 86 is removed and replaced with the dialcontrol knob 46 which is now set so that the speeds indicatedthereon check with the table speeds- The setting of the dial knob is accomplished by holding theknob against its slow speed stop while-turning the valve stem, using a screw driver fitted into the screw driverslot 94 for this purpose until the desired slow speedis reached. The locking "set screw 48 is now tightened, completing the operation.

It' has been found that the series of opera! tions above described are capable of securing a very accurate adjustment of the valve mechanism, forthe reason that each of the blanking off positions is arrived at separately, so that in each instance the aperture resultingfrom' the overlapping of adjacent edges of the ports 28 and 30 is the product of the very small dimension in the direction of overlapping and of a rela tively large transverse dimension, so that the efiective opening increases from zero very rapidly' It will be understood that the invention is not limited to the specific embodiment shown,.-and that various deviations may be made therefrom without departing from the spirit and scope of theiappended claims; '15

What is claimed is: l i

1. A hydraulic control valve which comprises a cylindrical valve element and a cylindrically chambered valve receiving element, said valve element and chambered valve receiving element having cooperating valve ports formed with rectilinear transverse and longitudinal edges sub stanti'ally square with the axis of" said cylindrical elements andarranged' to be brought into overlapping'r'elation by'movement of the valve element to provide a throttle, opening, a nut, an ex tension ofthe valve element threaded to the ma;

said valve and chambered valve receiving elements' being disposed with relation to one another so that the screw movement of the valve element relative to the nut effects a substantially simultaneous Loyerlapping of the cooperating transverse and cooperating longitudinal edges of said ports to increase, the area of thethrottle opening of said valve from closed to open posi'-' tion, and means supporting the nut in fixed I axial relation to the valve receiving element and for rotatable adjustment with relation thereto, whereby rotation of the screw from a fully closed position of the valve will indicate the adjusted angular position of the threaded extension with relation to said supporting means for the blank-' ing-off of said longitudinal edges, and a rotationaladjustment of the nut relativeto the threaded extensionwill indicate the adjusted position of the threaded extension axially with relation t'o' the nut -for the blanking-offof said transverse edgesr and'a subsequent rotational movement of thenut and threaded extension as a unit toLthe previously'adjusted angular position of the threaded extension will accurately determine the 'shut-ofi position of the Valve.

52. A hydraulic-control valve-which comprises a cylindrical valve elementand a cylindrically chambered valve receiving; element, said valve elementsiand' arranged to'be brought into over-' lapping relation'by movement ofthe valve element to provide athrottle opening, 'awnut', an-

extension'of the valve element threaded-to the nut, said valve and chambered valve receiving elements "being disposed-with relation to one another'so that the screw-'movement of the valve element relativeto-the nut efiects a substantially simultaneous overlapping of the cooperating" transverse and cooperating longitudinal edges-of said ports-to increase the area of thejthrottleopening of, said valve from closed to open position, means supporting the nut in fixed*axial-re-- lationto the valve receiving element and for rotational adjustment with relation to said threaded extension for adjustment of the rotational and axial position-of the threated extension to effect said simultaneous overlapping of said transverse and longitudinal edges, and spring means connected to bias the valve element axially against the nut and thereby to eliminate backlash in the threaded connection with the nut comprising :a coil spring coiled about and secured to the valve extension, and a sleeve thrust element engaged by said coil spring keyed to slide upon and turn with said sleeve extension.

3. A hydraulic control valve which comprises a cylindrical valve element and a cylindrically chambered valve receiving element, said valve element and chambered valve receiving element having cooperating valve ports formed with rectilinear transverse and longitudinal edges substantially square with the axis of said cylindrical elements and arranged to be brought into overlapping relation by movement of the valve element to provide a throttle opening, a nut, an extension of the valve element threaded to the nut, said valve element being disposed with relation to the chambered valve receiving element so that a screw movement of the valve element outwardly relative to the nut effects overlapping of the cooperating transverse and cooperating longitudinal edges of said ports to increase the area of the throttle opening of said valve from closed to open position, means supporting the nut in fixed axial relation to the valve receiving element and for rotational adjustment with relation to said threaded extension for adjustment of the rotational and axial position of said threaded extension to effect said simultaneous overlapping of said transverse and longitudinal edges, 9, manual control disposed at the outer end of said valve extension, and spring means connected to bias said valve element axially outwardly against the nut.

nut in a fixed axial relation to the valve receiving element and for rotational adjustment relative thereto, an extension of the valve element threaded to the nut, said valve and chambered valve receiving elements being disposed with relation to one another so that the screw movement tudinal edges, an indicator dial arranged for re tative adjustment on said valve extension to1accord witha relative angular blank-off position of said valve elements'and a rel-atively'fixed indicator cooperating with said dial.

5. A hydraulic control valve which comprises;

a cylindrical valve element and a cylindrically chambered valve receiving element, said valve element and chambered valve'receiving element" having cooperating valve ports formed with'rec tilinear transverse and longitudinal edgesi'substantially square with-the axis of saidcylindrical elements, a nut. threaded to the valve element, means for supporting the nut in a rotatably adjustable .axially fixed relation to the valvelreceiveing element for independent adjustment ofiitheLv axial and rotational position. of the threaded; valve element-for blanking-off of said respective. transverse and longitudinal .edges to effectr'a 1' simultaneous overlapping of said transverse and longitudinal edges, at adjacent corners of said ports moving from a closed to an open position, :a dial supporting manual controller secured to said valve element for adjustment angularly to accord with the rotationally adjusted blank-of]? position of the valve element, and a stop device acting against said manual controller to limit the rotational movement thereof.

6. A hydraulic control valve which comprises cylindrical valve and valve sleeve elements, said valve element having a semi-cylindrical cut-out formed at the inner end thereof to provide a port having rectilinear transverse and rectilinear longitudinal edges substantially square with the axis of said valve elements, said valve sleeve having formed therein a transverse slot of a length axially of the valve sleeve element less than the length of the cut-out in the valve element and of a depth extending nearly to the axis of the sleeve element to provide a side port having rectanuglar transverse and longitudinal edges, a nut threaded to one of said elements, a support on which the nut is fixed axially with relation to the other of said elements and for rotational adjustment with relation thereto for effecting an independent determination of the relative rotational and axial blanking-01f positions of said valve elements to efiect a simultaneous overlapping of said transverse and longitudinal edges for a throttled opening of the valve, and means for securing the nut to the support in an adjusted position.

7. A hydraulic control valve which comprises a cylindrical valve element and a cylindrically chambered valve receiving element, said valve element and chambered valve receiving element having cooperating valve ports formed with rectilinear transverse and longitudinal edges substantially square with the axis of said. valve elements and arranged to have adjacent corners thereof brought into overlapping relation by movement of the valve element to provide a throttle, a nut having a threaded connection with one of said cylindrical valve elements, a support on which the nut is fixed axially with relation to the other tional adjustment with relation thereto for effect.

ing an independent determination of the relative rotational and axial blank-off positions of said valve elements, means on said support marking theangular-blank-ofi position of the movable cylindrical valve element, means securing the nut to saidsupport for a position in which the mov-. able sleeve element is in said marked'rotational position and in which the nut and movable cylindrical valve element are in said determined axial blank-01f position, and a dial supporting manual controller rotatably adjustable on said movable valve' element to accord with the adjusted positions of said nut and threaded sleeve valve element.

8. A hydraulic control valve which comprises cylindrical valve and valve; sleeve elements, said valve element having a semi-cylindrical cut-out formed at the inner end thereof to provide a port having rectilinear transverse and rectilinear longitudinal edges substantially square with the axis of said valve elements, said valve sleeve having formed therein a transverse slotof a length axially of the valve sleeve element less than the length of the cut-out in the valve element and of a depth extending nearly to the axis of the sleeve element to provide a side port having rectilinear transverse and longitudinal edges, a nut, a

threaded. extension of said valve element threaded to the nut, said valve and sleeve elements being disposed with relation to one another so that I a screw movement of the vlave element outwardly relative to the nut effects a substantially simultaneous overlapping atadjacent corners of the cooperating transverse and longitudinal edges of; said portsto open the valve, means including a ring clamp supportingthe nut in fixed axial re- I lation to the valve receiving element and for rotational adjustment with relation thereto to determine the relative angular and relative axial blank-off positions of said valve elements, and a dial supporting manual controller angularly ad justable on said .valve extension in accordance with the angularly adjusted blank-01f position of said valve extension. I

' v HANS C. WEIMAR.

REFERENCES CITED The following references are of record in the file' of this patent: f

UNITED STATES PATENTS

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