US2420557A

US2420557A - Impeller pump

Info

Publication number: US2420557A
Application number: US534022A
Authority: US
Inventors: Alexander V Mueller
Original assignee: Individual
Current assignee: Deming Co
Priority date: 1944-05-04
Filing date: 1944-05-04
Publication date: 1947-05-13
Anticipated expiration: 1964-05-13

Description

' May 13, 1947. A. v. MUELLER v 2,420,557

IIIPELLER PUMP Filed llay 4, 1944 3 Sheets-Sheet 1 Ha. I

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May 13, 1947. I v, MUELLER I 2,420,557

IHPELLER PUIP Filed lay 4. 1944 3 Sheets-Sheet 2 I IN V EN TOR.

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IIPELLER PUIP Filed lay 4, 1944 L 3 Sheets-Shear, 3

13/ H7 07 /04 I ma IN VEN TOR. AL EXANDE'R VNuz-usn Patented May '13, 1947 IMPELLER PUMP Alexander V. Mueller, Salem, Ohio, assignor to The Deming Company, Salem, Ohio, a corporation of Ohio Application May 4, 1944, Serial No. 534,022

This invention relates to a pump of the type having a rotary impeller within an enclosing casing carrying walls in close proximity to the impeller, and an object of the invention is to provide means for increasing the efliciency of such a pump by preventing or greatly reducing leakage about the impeller.

More particularly, the invention relates to an impeller pump having a rotary impeller with an annular row of vanes or buckets adjacent its periphery, such impeller being mounted between two frame members which stand adjacent the impeller and one or both of which cooperate with the buckets and extend across the periphery of the impeller and carry an annular water passageway with which spaced intake and discharge passages communicate. In pumps of this type it has been customary to make the frame members or stationary heads stand very close to the face of the impeller, while out of contact therewith, and hence there has been always some leakage between the faces of the impeller and the heads, reducing the efficiency of the pump. Furthermore, this leakage water frequently carries grit with it which scores the faces of the impeller and progressively diminishes its effective operation.

My invention provides pressure seals having annular faces which are maintained in actual contact with the faces of the impeller by continuous pressure, with the result that the leakage j and consequent scoring is practically eliminated.

In this respect the present invention is an improvement on that shown, described and claimed in mycopending application, Ser. No. 511,577,

filed November 24, 1943. The present invention provides also improved means to prevent leakage between the pressure seals and the stationary frame members in which they are mounted. Accordingly, leakage is prevented around the exterior of the seals, as well as between them and the impeller. These features have a further advantage of avoiding the requirements for stufiing boxes about the shaft to prevent leakage from the pump.

My invention is hereinafter more fully explained in connection with two embodiments thereof, illustrated in the drawings, and the essential novel features are summarized in the claims.

In the drawings, Fig. 1 is a, vertical axial section through one embodiment of my impeller pump; Fig. 2 is a substantially central vertical cross-section on a. reduced scale at right angles to Fig. 1, as indicated by the line 22 on Fig. 1; Fig. 3 is a fragmentary vertical cross section 24 Claims. (c1.103111) through one of the pressure seals for the impeller, the plane of the section being indicated by the line 3-3 on Fig. 1; Fig.) 4 is a side elevation of either of a pair, of diaphragms for preventing leakage between the pressure seals and the casing; Fig. 5 is a perspective of a portion of the pump at the cut-water between the intake and discharge passages at the periphery of the impeller; Fig. 6 is a central vertical section of a portion of the pump having another embodiment of any provision for preventing leakage; Fig. 'l

.is a fragmentary, transverse section of the emever, that the invention is not confined to the 'pump construction illustrated.

In the form shown in Figs. 1 and 2, the frame of the pump comprises a vertical ring-like member l0 having a suitable base portion II and carrying at the top a'hollow discharge chamber l2, which a may be integral with the ring of the frame or attached thereto. This view shows two end members l3 and M- which abut the sides of the frame ring Ill and are secured thereto, cap screws (one of which is indicated at l5) passing through flanges l6 and H on the end members, being shown for this purpose. Each of the frame members l3 and I4 is shown as having a cylindrical portion to the outer end of which an inwardly extending annular member I8 is secured, as by cap screws I9.

20 indicates the driving shaft of the pump which is mounted in suitable bearings, not shown. This shaft carries the impeller 30 which coacts with members to be described. The impeller is shown as keyed at 3| to the shaft and longitudinally positioned by being mounted between a pair of sleeves 2| on the shaft which are forced against the impeller by nuts 22 screwing onto threaded portions 24 on the shaft. This makes a. simple construction rigidly securing the impeller to the shaft in the desired position while enabling ready installation of the impeller on the shaft or its removal therefrom, if required. I

The impeller 30 is of ageneral disc form, and carries an annular row of buckets adjacent its periphery. The actual form or direction of the buckets may vary and they may be on one or both sides of the impeller, as desired. I have shown buckets made by radial notches 32 in opposlte sides of the impeller, the notches on either side leaving between them radial vanes 33. These pressure seal. In Fig, 6, each seal has two diavanes operate in an annular passageway provided by two stationary heads or frame members 40. These heads are mounted within the frame ring I and abut each other at their inner faces. They are shown as abutted at their outer faces by the inner ends of the frame members I3 and I4.

These heads therefore, when the pump is assembled, constitute part of the stationary frame of the pump.

One of the frame members I3 or I4 may be bolted snug without a gasket against the ring I0, but I prefer to employ a gasket (indicated at 25 in Fig. 1) between the flange of theother member, as I4, and the central ring member, the latter frame member in this case being the one which would be removed to obtain access to the interior of the pump.

, The heads 40 are symmetrical, each formed with smooth nearly annular face 4| adjacent its periphery, which faces abut each other tightly. Within the nearly annularly regions II and opposite the buckets 32 and beyond the periphery of the impeller, in the form shown, are formed grooves 42 which coact to make the annular passageway in which the buckets travel. This annular passageway leads from an intake passage 44 communicating with the suction or supply chamber 50 of the pump. Another nearly radial passageway 46 leads from the annular raceway 42 to the discharge port 4'! in the frame ring and thence to the discharge chamber l2.

Between the intake or suction passage 44 and the discharge passage 41 is mounted the so-called cut-water separating these passages. This may comprise a bifurcated block 60 (Figs. 2 and 5) occupying the raceway in this location and straddling the impeller and thus blocking the passage of liquid about the impeller buckets from the discharge passage to the intake passage, except such small amount as may be carried by the buckets 32 themselves moving past the block.

I have given above a description of the partlcular pump illustrated in Figs. 1 and 2 of the drawings in order that the application and function of the sealing means constituting my invention about to be described may be better understood. pSuch sealing means, however, is capable of a wide variety of application to impeller pumps differing materially from that above speciflcally described.

Heretofore in impeller pumps such as above described it has been customary to extend the stationary heads 40 inwardly close to the face of the impeller and continue them into a region near the shaft, where they have been providedwith external stuffing boxes preventing discharge of the water, which leaked inward between the impeller and such stationary heads. In my inven tion, however, I eliminate the leakage and the necessity for the stuffing boxes by a novel constructlon at the sides of the impeller, which I will now describe.

In the hollow interior of each frame member I3 and I4, I place two annular pressure heads or seals which have smooth inner faces contactingfwiththe faces of the impeller. These heads are spring-pressed into actual contact with the impeller and constantly maintained in such contact, and maintained in liquid-tight connection with the corresponding frame members, by a means of annular diaphragms attached at their inner margins to the pressure seals and at their outer margins to the pump frame. In Fig. 1, I have shown one of these diaphragms for each counter-balancing of the pressure acting on the seal, as later described. I

In the embodiment of Figs. 1 to 5, an extension sleeve 80 is threaded on the exterior of each pressure seal I0 and is externally mounted slldably in a bearing in the frame member I3 or I4. Each extension'sleeve has an inwardly extending annular flange 0| with an annular rib 82 on the face distant from the seal. Helical compression springs I5 surround the shaft and are seated at their inner ends in the annular recesses beyond the ribs 82 and at their outer ends in annular recesses 83 formed on the inner faces of the stationary annular members I8. These springs accordingly maintain a constant pressure of the smooth inner ends of the seal rings I0 against the smooth side faces of the impeller 30.

Set screws 85 mounted in the frame members I3 and I4 extend into recesses 86 formed in the outer periphery of the sleeves 80 and prevent .rotation of these sleeves without interfering with the longitudinal movement thereof, the springs not reaching the bottom of the grooves 86.. The long sleeves in their bearings insure accurate presentation of the faces of the seals to the impeller.

The pressure of the smooth seals against the smooth face of the impeller practically eliminates leakage between these parts. To prevent leakage between the seals and the pump casing, I provide the yielding annular c'liaphragms in the form shown in Figs. 1 and 4. These annular members are of rubber or similar impervious flexible material and each has an outer annular fiat portion 9| clamped between the frame member I3 or I4 and the adjacent stationary head 40; then each diaphragm has an annular conical portion 92 inclining toward the impeller and lying along a conical edge 48 of a thinned annular portion 49 of the ring 40, and beyond this the diaphragm has a fiat annular portion 93 parallel with the portion 9| and offset therefrom. This innermost flat portion 93 of the diaphragm closely surrounds the hub portion of the seal I0 and rests against the outer side of the face portion 'II thereof and is clamped against that portion by the extension sleeve 80, preferably through an interposed washer 95.

In assembling the pump each diaphragm may be put into position over the hub of a seal against the flange 'II thereof, the washer 95 put in place on the other side of the diaphragm and then the sleeve 90 screwed into place on the seal to clamp the diaphragm in a water-tight manner to the seal.

The seals with the diaphragms and extension sleeves may then be put into place in the respective frame heads I3 and I l and the latter bolted against the central frame ring ID to clamp the outward annular extensions 9| of the diaphragm in a water-tight manner between the inner annular portions 49 of the frame heads 40 and the frame members. Then the springs I5 may be put in place against the flanges of the sleeves 80. Then, when the end members I8 are bolted in place, the springs are compressed against the extension sleeves and the seals are thus brought into snug and constant pressure against the opposite faces of the impeller.

In the embodiment shown in Figs. 6 and 7, the shaft I00 carries an impeller IOI, clamped between sleeves I02 held by nuts I03, and this impeller has peripheral vanes IIlll operating in an On opposite sides of the impeller, I mount the annular pressure seals I20, each of which has a head and a cylindrical sleeve portion |2I of considerable length, and threaded onto the exterior of this sleeve portion is an extension sleeve I25. Coiled compression springs I are mounted between the extension sleeves and annular end caps I2'I, which are tightly secured to the frame heads I05 and constitute in operation part of the stationary frame of the pump. It will be seen that. the springs I26 acting toward each other maintain the pressure seals in snug engagement with the opposite faces of the impeller, thus practically preventing leakage between the seals and the impeller.

To prevent leakage from the annular passageway I05 by a course outside of the impeller, I provide a somewhat different arrangement of diaphragms from that heretofore described. Thus, I mount within each frame head I06 a ring I30 and I place one annular diaphragm I3I with its exterior margin between the ring I30 and a flange I32 on the frame head and another annular diaphragm I35 with its exterior margin between the ring I30 and the frame cap I21. The inner margin of the diaphragm I3I is clamped between the head of the pressure seal and a clamping ring I31 surrounding the sleeve portion of the seal, there being preferably an interposed washer I38 between the clamping ring and diaphragm margin. The other diaphragm I35 has its inner margin clamped between the outer end of the clamping ring I31 and the washer I39 mounted in a rabbet in the end of the extension sleeve I25.

It will be seen that when the extension sleeve I05 is turned onto ttthe seal sleeve to the limit of its movement, it will tightly clamp the inner margins of both diaphragms of the pressure seal.

Likewise, the tightening of the frame cap I21 against the frame heads will clamp the outer margin of the two seals to the frame. Thus there is no possibility .of leakage from the impeller chamber around the outside of the seals.

It will be seen from Fig. 6 that the ring I30 between the two diaphragms has a radial opening I40 in it and this opening comunicates by a suitable conduit with some convenient region of the conduit carrying the discharged liquid. As shown, this connection is made by a passageway I4I, Hi2, leading from the ring opening I40 to the discharge passage III. The result is that the space between the two diaphragms associated with either seal is filled with liquid under the pressure 'of the liquid discharged. There is space between cause a balance between the effective pressures on the two diaphragms, diaphragm I3I being subjected on its other side to counteracting pressure in the impeller chamber. The pressure around the impeller averages materially less than the ultimate discharge pressure which is acting to push the diaphragm I3I toward the impeller. Hence, the effective pressure toward the impeller is the difference between the ultimate discharge pressure and the average" pressure about t e impeller. On the other hand-the diaphragm I35 on its outer side merely encounters atmospheric pressure so that the full discharge pressure is acting outwardly against that diaphragm.

I make the effective area of diaphragm I3l (which is dependent upon the area of the annular space between the two clamping rings) enough larger than the effective area of the other diaphragm to compensate for the reduced effective pressure acting toward the impeller on dia phragm I3I, and thus substantially balance the outward pressure against the two diaphragms from between them, with the result that the hydraulic pressures are without effect on the seal. Accordingly, the seal will contact with the impeller by a pressure determined merely by the spring I26, independent of the pressure developed by the pump. This enables me to use a comparatively light spring, causing just sufiicient friction between the seal and the impeller to maintain a substantially liquid-tight connection.

As the average pressure in the impeller chamber is substantially half that in the discharge passageway, I can obtain the desired balance by making the effective area of the diaphragm adjacent the impeller twice that of the other diaphragm.

Explaining further this balancing of pressures, by way of concrete example, if the liquid enters the impeller chamber through the suction passageway H0 at zero pressure and is discharged out of the annular passageway at 100 lbs. per

square inch pressure, the average pressure about the interior of the ring I30 and the exterior of the III leading to the diaphragm I35. This is done to the impeller would be substantially 50 lbs. Accordingly, in such instance there would be lbs. pressure between the two diaphragms shoving with 100 lbs. per square inch against the outer diaphragm I35 and shoving against the other ,diaphragm with an effective pressure of 50 lbs. per square inch on twice as large an area. Ac-

cordingly, I prefer to make the passageway I45 of substantially twice the cross sectional area of the passageway I so that the effects on the two diaphragms are equal.

It will be seen that in each embodiment the yielding diaphragms enable original and proper positioning of the parts in a water-tight manner and provide also for inward movement of the seals under spring pressure, as wear on the'rubbing faces of the impeller and sealing rings takes place. Accordingly, any leakage of liquid from the annular chamber or buckets across the outside of the seals is absolutely prevented. Leakage between the faces of the seals and the impeller ieaizage is more than an insignificant amount its presence will indicate to the user that the pump should be taken apart and the face of the impeller or the seal re-lapped. Such re-lapping may be readily effected by suitable application of pumice and oil on a perfectly flat plate.

It will be seen that by eliminating the leakage in any material quantity, I have increased the efficiency of the pump. There will, however, naturally be a film of liquid between the faces of the seals and the sides of the impeller sufficient for lubricating purposes and, accordingly, my leakage-prevention is efiected without a material increase in friction. The slight increase in friction in this region is compensated by the avoidance of the friction inherent in stuffing boxes.

Furthermore, it will be seen that by reason of the yielding character of the diaphragms and the permissible movement of the springs to press the seals, a considerable grinding away of the faces of the impeller or the ends of the seals may be efi'ected without interfering with the operation of the pump and hence the repairs may be repeated whenever necessary, thus giving a long life to the pump.

I claim:

1. In a pump, the combination of a frame, a shaft, an impeller on the shaft, an internal head carryin a water passageway for the impeller, an external clamping head secured to the pump frame and abutting said internal head, an annular diaphragm clamped between said internal and external heads, an annular seal about the shaft abutting the face of the impeller, means for clamping the diaphragm to said seal and means for supplying spring pressure to the seal to maintain it in pressure engagement with the impeller.

2. In a pump, the combination of a frame having a cylindrical opening, a pair of internal annular frame heads occupying said opening and having mating grooves to define an annular water passageway with intake and discharge passages, a pair of external heads secured to the frame and clamping against the internal heads, each of said external heads having a tubular portion surrounding the shaft, annnular seals surrounding the shaft abutting opposite faces of the impeller, each seal having an extension sleeve threaded thereto, helical compression springs surrounding the shaft and hearing at their inner ends against internal flanges of the sleeves, members secured to the outer ends of the external frame heads and carrying means to press against the springs to force the seals against the impeller, and annular diaphragms surrounding the seals and clamped adjacent their inner peripheries between external flanges on the seals and the inner ends of the extension sleeves, the outer portion of said diaphragms being clamped between said internal and external heads of the stationary frame.

3. In a pump, the combination of a casing and a rotary impeller, a sealing ring engaging the face of the impeller, a pair of yielding annular members spaced apart and fixed to the sealing ring and to the casing, and means fo admitting pressure to the space between said annular members.

4. In a pump, the combination of a rotary impeller havin vanes, means defining a passageway in which the impeller vanes travel, a movable seal member engaging the face of the impeller between its axis and its vanes, a pair of yielding annular members fixed adjacent their inner peripheries to the seal member and adjacent the oute periphery to the pump casing,

and means for admitting fluid under pressure to the space between said yielding annular members.

5. In a pump, the combination of a casing, a rotary impeller, a sealing ring engaging the face of the impeller, a pair of spaced annular diaphragms each having its inner margin attached in a liquid tight manner to the sealing ring and its outer margin attached in a liquid tight manner to the casing, a conduit from the discharge conduit of the pump to the space between the diaphragms to admit fluid under pressure into such space, one of such diaphragms being subjected on the face adjacent the impeller to the pressure in the impeller chamber, and means whereby the last-mentioned diaphragm has a larger area acted on by the pressure between the diaphragms than does the other diaphragm.

6. In a pump, the combination of a casing pro- .viding an annular chamber with intake and discharge passages communicating therewith, a rotary impeller in said chamber, annular sealing rings engaging opposite faces of the impeller, each sealing ring being pressed toward the impeller by a spring, a pair of diaphragms for each sealing ring connected at their inner margins to the ring and their outer margins to the casing, one of said diaphragms being subjected on the side adjacent the impeller to the pressure in the impeller chamber and both the diaphragms being subjected between them to pressure corresponding to the discharge pressure of the pump, and means between the diaphragms for causing the annular area of that diaphragm which is subjected to the pressure in the impeller chamher to be substantially twice that of the annular area of the other diaphragm acted on by pressure.

'7. In a pump, the combination of a casing, a shaft mounted therein, a vaned impeller on the shaft, means providing an annular chamber in which the impeller vanes may operate, said chamher having intake and discharge passages, an

annular pressure seal engaging a face of the impeller, said seal having a disc-like portion contacting the impeller and a sleeve-like portion surrounding the shaft, an extension sleeve threaded on the sleeve-like portion of the seal, a clamping.

ring between the extension sleeve and the disclike portion of the seal, a pair of diaphragms having their inner margins clamped respectively between the clamping ring and said disc-like portion and between the clamping ring and said extension sleeve, means for clamping the outer margins of said two diaphragms to the casing, means for admitting fluid under pressure to the space between the diaphragms, and a spring acting to force the seal against the impeller.

8. In a pump, the combination of a pump casing having an impeller chamber with intake and discharge passages, a rotary shaft, the impeller thereon having vanes occupying the impeller chamber, a pressure seal surrounding the shaft and engaging a face of the impeller, a pair of spaced diaphragms connected at their inner margins with the pressure seal, a ring between the outer margins of the diaphragms serving to clamp each of them against the assembled casing, there being spaces at the inner periphery of the ring leading to the two diaphragms, and a conduit for conveying fluid under pressure to such space.

9. In a pump, the combination of a casing providing an impeller chamber with intake and exit I to the casing.

passages, a shaft, a rotary impeller thereon occupying the impeller chamber, a pressure seal bearing against a face of the impeller and including an annular head with a rigid sleeve extending therefrom concentric of the shaft, an extension sleeve threaded to the seal sleeve, a clamping ring btween the extension sleeve and the seal head, a pair of diaphragms having their inner margins clamped respectively between the clamping ring and the seal head and between the clamping ring and the extension sleeve, a second clamping ring outside of the ring first mentioned and spaced from it and standing between the Outer margins of the two 'diap'hragms and clamping such margins against the casing, said latter clamping ring having an opening to admit pressure to the space betwen the rings, which space communicates with the twodiaphragms, the passageway between the rings to the diaphragm which is adjacent the impeller being greater than the passageway to the other diaphragm, and means for conducting fluid under pressure from the discharge of the pump to the space between margin to means maintained in engagement with the seal. a

11. In a pump, the combination of a casing, a rotary impeller therein having an annular row of buckets open outwardly but closed at their bases, a sealing ring engaging the face of the impeller close to the bases of the buckets, and means secured tightly to both the ring and the peller buckets travel, a seal member engaging the face of the impeller directly adjacent to the base of the buckets, an abutment member engaging the seal member, and one ol' the engagements mentioned being fixed and the other slipping, a spring bearing against such abutment member and maintaining the slipping engagement snug, a pair of yielding annular members fixed adjacent their inner peripheries to one of the members mentioned and adjacent their outer peripheries to the pump casing, and a conduit for phragms, each'having its inner marginattached f in a liquidtight manner to one of the members casing to prevent leakage across the outside of the ring.

12. In a pump, the combination oi a casing, a rotary impeller having an annular row of buckets open outwardly but closed at their bases, a sealing ring engaging the face of the impeller close to the bases of the buckets, means to maintain a pressure against the sealing ring and a yielding annular member fixed to a. part of said means and 13.-In a pump, the combination of a casing, a

rotary impeller therein, a sealing ring engaging the face of the impeller, a non-rotating member engaging the sealing ring, a. pair of yielding annular diaphragms spaced apart and aflixed to said non-rotating member, and a conduit for admitting fiuid under pressure to the space between the diaphragms.-

14. In a pump, the combination of a casing, a rotary impeller therein, an abutment member in the casing, an annular seal member between the abutment member and impeller engaging each of them,'one of such engagements being fixed and the other slipping, and two diaphragms preventing leakage between the seal and the casing, said diaphragms being secured at their of open-sided buckets adjacent its periphery,

means defining a passageway in which the immentioned and attached at their outer margins in a liquidtight manner to the casing to prevent leakage over the periphery of the sealing member from the impeller buckets, and a conduit from the discharge of the pump to the space between the diaphfagms to admit fluid under pressure to such space, the diaphragm which is subjected to pressure toward the impeller havinga larger effective area than the other diaphragm.

17. The combination of a casing. a shaft, a rotary impeller thereon within the casing hav-- ing a peripheral row of buckets closed at their inner ends and open at their outer sides, a sealing ring surrounding the shaft and abutting the side of the impeller, a yielding annular diaphragm surrounding the sealing ring' and clamped thereto, means for clamping the outer region of the diaphragm to the casing, and a spring acting on the sealing ring and'pressing it against the impeller, 45

18. In a pump, the combination of a casing, a rotary shaft, an impeller thereon within the casing and having an annular row of vanes adiacent its periphery providing buckets closed at their inner ends and open at their outer sides, means carried by the casing defining a passageway in which the vanes travel, a movable sealing ring surrounding the shaft and engaging the face of the impeller in the annular space between the row of vanes and the shaft, a sleeve connected to the sealing ring, a spring acting on said sleeve 1'01- pressing such sealing ring into [contact with the side of the impeller, and means preventing leakage about the periphery of said ring.

19. In a pump, the combination of a casing, a rotary shaft, an impeller thereon within the casing and having an annular row of vanes adjacent its periphery, means providing intake and discharge passageways each communicating directly with the peripheral space between said vanes, means carried by thecasing defining a passageway in which the vanes travel, a movable -sealing.ring surrounding the shaft and engaging the impeller adjacent the inner edges of the vanes, a sleeve slidably guided inthe casing and connected to the sealing ring, a spring pressing the sleeve toward the impeller, and means pre venting leakage about the periphery of said ring.

20. In a pump, the combination of a casing, a rotary impeller therein having a peripheral row of buckets, means providing intake and discharge passageways communicating directly with said buckets adjacent the periphery of the impeller, a sealing ring abutting the face of the impeller having an external annular flange, a yielding diaphragm engaging the flange, and means including rotary impelling ripheral row of buckets, means providing intake an extension sleeve screwing onto the sealing ring for clamping the diaphragm against the flange, a spring pressing the extension toward the impeller and means for clamping the outer region of the diaphragm to the pump casing.

'21. In a pump, the combination of a casing, a

shaft therein, a rotary impeller on the shaft' the combination of a casing, a member therein having a pe- 23. In a pump,

and discharge passageways communicating directly with said buckets adjacent the periphery of the impeller, 'a non-rotary member inthe cas ing, an annular seal intermediate of said members and secured to one of them and having a slipping 22. In a pump, the combination of a casing,

a shaft therein, a rotary impeller on the shaft within the casing having a peripheral row of buckets, means providing intake iind discharge passageways communicating directly with said buckets adjacent the periphery of the impeller, an annular sealing ring surrounding the shaft and abutting the impeller, an extension sleeve secured to the sealing ring and having its exterior mounted slidably in a bearing in the casing. a helical compression spring surrounding the shaft and acting to press the sealing ring against the impeller, andmeans carried by the casingcoacte ing with a longitudinal guide on the sleeve to prevent rotation of the sleeve while allowing it to mov axially.

connection with the other, a yielding diaphragm connected to the casing and to said non-rotary member, and a spring acting on the non-rotary member to maintain said slipping connection snug.

24. In a pump, the combination of a casing, a rotary impeller therein having a peripheral row of buckets, means providing intake and discharge passageways communicating directly with said buckets adjacent the periphery of the impeller, a non-rotary sealing member engaging the face of the impeller, means to maintain a pressure between the sealing member and the impeller, and a flexible impervious member secured tightly to said sealing member and said casting.

ALEXANDER V. MUELLER.

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

UNITED STATES PATENTS Number Name Date 1,198,558 Lawaczeck Sept. 19, 1916 1,483,645 Sessions Feb. 12, 1924 1,884,974 Hurd Oct. 25, 1932 1,972,548 Brady, Jr Sept. 5, 1934 ,02 ,898 Olson Dec. 10, 1935 2,113,116 McMillan Apr. 5, 1938 2,195,877 Steedman" Apr. 2, 1940 2,311,494 Vedovell Feb. 16, 1943