US1047261A - Screw-propeller pump. - Google Patents

Description

P. MARBURG, JR. SCREW PROPELLER PUMP.

APPLIUATION FILED SEPT.. 23, 1903.

1,047,261 Patented Dec. 17, 1912.

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APPLICATION FILED $131,123, 190s.

1,047,26L I Patented B60121912.

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SCREW PROELLER PUMP.

APPLICATION FILED SEPT. 23,1903.

1,047,261 Patented Deo. 17, 1912.

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FRANZ MRBURG, JR., 0E NEW YORK, N. Y.

SCREW-PROPELLER PUMP.

Specification of Letters Patent.

Patented Dec. 17, 1912.

Application filed September 23, 1903. Serial No. 174,249.

To all whom t may concern Be it known that I, FRANZ MARBURG, Jr., a citizen o-f the United States, residing in the borough of Brooklyn, in the county of Kings, in the city and State of New York, have invented certain new and useful. Improvements in Screw-Propeller Pumps, vof whichthe following is a specification.

This invention relates to axial propeller pumps, and the object of the invention is, in part, to improve the shape of the screw, in part to simplify the construction and increase the efficiency of the pump; and in part to provide simple means for balancing the thrust of end-pressure on the shaft.

In the accompanying drawings, which illustrate an 'embodiment of the invention, Figure 1 is a longitudinal, horizontal-axial section of the pump, and Fig. 2 is a similar vertical section of the same. Figs. 3, 4, 5, 6, 7, 8 and 9 are, respectively, transverse sectionsv atlines w3, x4, m5, w, m7, w8 and ai" in the principal views. In Fig. -1 the-screw is shown in elevation and in Fig. 2 it is represented in section.

1 designates the elongated and substantially cylindrical casing of the pump, which is provided with heads 2 and 3. In the head 2 is the inlet 4, and in the casing itself is the outlet. 5. Extending through the casing axially is the pump-shaft 6, which has a bearing 7 in the casing and another bearing 8 .in the head 2. On the shaft 6, which has a little endwise movement in its bearings, is secured the screw 9. AThis screw has an elongated, tapered body rounded at its larger end, and is provided7 as herein represented, with two spiral blades somewhat in the form These blades are disposed at the larger conical end or part of the body, adjacent to the pump-inlet, the

-blades beginning at-the part of the core or screw-bodywhich has the greatest diameter and extending to a part of said body of lesser diameter, and the'lesser end of the screw-body is naked, or without blades. The outer contour of the main middle pory tion of the screw is shown cylindrical, which v screw outlet.

vis preferable as it allows endwise movement of thescrew and of the shaft. The screwbody being tapered from the screw-inlet toward the screw-outlet, it follows, that the fully radial width of the screw-blade, and consequently the capacity of the screw, increases from the screw-inlet toward the l/Vherever the expression main middle portion or main portion of the screw or 'of the blade is used, it signifies the part of the screw or of the screwblade which is at its outer contour in close proximity to the wall of the casing and the expression full radial width -of the screwblade signifies the radial width of said blade at the main po-rtion of the screw only. The pitch of the spiral of the blades gradually increases from the receiving end, and the blades increase gradually to their full radial width from their respective ends toward the main middle portion of the screw. The object of this construction is to reduce the shock caused by the fluid entering the screw while the latter is rotating at a high velocity, and also to prevent suction and undue whirling at the screw-outlet. The bore in the casing where the blades of the screw are situated may be` substantially cylindrical, but it may be gradually flared or enlarged at pointsadjacent to the ends ofthe blades, as seen at 10 in the principal views.

, The shaft being rotated in the proper direction, the fluid enters through the main inlet to a chamber 11 (Fig. 2) in the head 2,

and is drawn by the blades of the screw through the annular space. between the larger part of the screw-body and the casing, and is forced into a delivery chamber 12, in the casing, which chamber is connected with the eduction o utlet I5 of the pump. i

In forcing the fluid under ahead toward the outlet the'screw tends to move or be forced back toward thevinlet,lor to the left in the principal views, and this lputs an endthrust or pressure on the shaft Gwhich it is very necessary to obviate by counterbalancing. To effect this the head 3 is constructed to form a cylindrical piston-chamber 13,- and on the shaft 6 is secured a piston 14, which may rotate loosely ,or freely in said chamber and also move endwise therein with the shaft. The chamber 13 is open at the inner face of the piston 14, to fluid from the, outlet 5, through a pass/age 15, so that the liquid may press on the piston 14 with substantially the pressure due to the head atthe main outlet, and acting on the piston in the opposite axial direction as on the screw; but as the piston 14 fits loosely in the chamber, a small quantity of the fluid may flow pastit into the chamber atits outer side.

Opening from the outer part of the cham- .l ber is an exhaust-port 16, leading into a pas-4 sage or conduit 17, which extends back to the inlet chamber 11. This port 16 is adapted to be closed by a valve 18 on the end of the shaft 6, when the latter is moved endwise toward the right under the pressure of l .the fluid behind the piston 14.

The operation of this device is substantially as follows: When the pump is set in motion the liquid under a pressure at the outlet acts on the piston to move the shaft endwise, to the right as seen in the principal views, and to cause the valve 1S to close the exhaust-'port 16. But as a small quantity of the fluid may find its way past the piston, as

explained, the valve-chest will lill at the outer side o-f the piston 14, and the pressure be increased thereon, thus tending to bal-- ance the pressure on both faces thereof. However, as the pressure tends to be thus equalized the pressure on the screw will move `the shaft and the piston 14 to the left,

will be kept cool bythe water flowing about and in contact with them at all times while the pump is in operation. The blades of the screw 9 will also rotate out of contact with the casing, but of course in near proximity thereto.

In order to supply the bearings with oil lfor lubrication, an oil-chamber 19 is pro-- vided in the head 2, about the bearing `8, and a similar chamber 20 is provided in the casing about the bearing 7. There are oil-holes 21 in the bearings, as seen in Figs. 7 and 9,

' and oil-inlets for supplying oil to the chambers, closed by screw-plugs 22.

The object of the construction of the screw 9 as shown in the drawing, and as described, will now be fully explained. A

I have found by carefully conducted eX- periments that the. main diiiculty with screw-pumps, if operating against a high head, is the unavoidable slip of the fluid, the axial velocity of the fluid being approximately only from one-half to one-quarter of the forward velocity of the spiral blade, the slip increasing with the pressure against whichthepurnppperates. As a result of this action there is a heavy shock or blow when the fluid-enters the screw, and a consequent sudden high peripheral velocity and whirlingof the Huid with consequent loss 'of energy and efficiency. After the fluid has attained a high peripheral velocity, little'or no pressure in a forward direction can further be exerted on the fluid by the spiral blades. It is not the object of this invention to prevent the slip, but it is rather the intention to produce a screw wherein this un-Y avoidable slip can take place gradually from the 'screw-inlet toward the screw-outlet. rlhe sectional area or capacity atl the screwoutlet is greater 'than the sectional area or capacity at the screw-inlet, taken in a plane at right-angles to the screw-axis, and as a result the Huid will travel at a greater axial velocity at the screw-inlet than at the screwoutlet, the axial velocity of the iuid at the screw-inlet` being equal or nearly equal to the peripheral velocity of the screw blade multiplied by the tangent o-f the angle which the blade forms at the screw-inlet with a vertical plaiie through the pump axis. Thus it will be clearly seen that the pressure exerted by the spiral blade on the fluid increases gradually as the axial velocity of the fluid decreases, the pressure being greatest atthe screw-outlet, or at the point of greatest sectional area or capacity. The increase of the pitch of the spiral blade and the increase of the full radial width of the spiral-blade, both produce increasing capacity from the screw-inlet toward the screw-outlet, and in the construction shown in the drawings the increasing pitch of the spiral blade toward the delivery end of the screw accentuates the increase of pressure on the fluid, as the blade travelsforward in an axial direction with increasing Speed, while the fluid iows forward with decreasing speed. .It is also clear that it is essential, in all cases, that the screw-outlet capacity should be greater than the screw-inlet capacity. I do not claim an increase of capacity of any part of the screw, oran increase of the pitch of any part of the spiral blade, and smaller screw-outlet capacity than screw-inlet capacity, as shown in the patent to Miles and Sto-rch No. 736,421, but I claim a greater screw-outlet capacity than screw-inlet capacity.

It is important in a pumpas embodied in this invention, that the full radial width of .thescrew-blade should be less than one-sixth part of the corresponding diameter of the outer contour of the screw.V The importance of this proportion I have proved by experiments. If'the radial width of the screwblade is greater than stated herein, the efliciency of the pump as herein described is low, either through backfiow of `the fluid at the inner portion of the screw-blade, nearest the pump-axis, while operating under great pressure or head at the discharge outlet, or through a large over-expenditure of energy at the outer portion of the screwblade. The first loss occurs if the angular velocity of the screw, and consequently the peripheral velocity of the screw-blade, is

' lished byv me through experiment.

not sufficient at its inner portion or near the ump-axis, to create the'required pressure; the latter loss occurs, if the angular velocity is sufficient to create the required pressure at the inner portion of the blade, in which case the outer portion of the blade travels with a greater velocity than necessary to produce the required pressure or head. The amount of these losses caribe estimated from the following rules which have been estab- The pressure produced and which can be utilized by this pump, is proportional to the square of the peripheral'velocity of the screw-blade or vany portion thereof. The capacity increases in this particular pump about directly proportional to the velocity of the screw-blade, at vario-us pressures within certain limits, while the amount of energy necessary to operate this pump is proportional to the cube of the peripheral velocity of the screw-blade or any portion thereof. These rules are substantially correct only in a screw-pump of a smaller inlet capacity than outlet capacity, and the amount of energy used at a given velocity of the screw-blades is very nearly independent of the pressure or head at the main discharge outlet of the pump. The reduced or limited inlet area or capacity of the screw produces a more nearly constant discharge against different heads o-r pressures, and for this reason a high peripheral velocit-y is always imparted to the fluid in a pump of this character. However, if this pump is operated at the proper speed for each pressure or head, and

if the full radial width of the screw-blade is within the limits'above stated, and if a fixed director of the proper shape, or other means are employed to gradually reduce the high velocity of the fluid adjacent to the screw-outlet,v then in that case, the efficiency of the pump 1s very high. Y

One other unavoidable feature of these" pumps, as just stated, is the resultant high rotary velocity of the fluid abo-ut the pumpaxis at the discharge end of the screw; and the object of the anuularspace or chamber adjacent to the screw-outlet, and of the gradual chamber in the direction from the screw-outlet, is to gradually reduce this high rotary velocity and thus to utilize a part of this energy by transforming it into useful pressure, thereby increasing the efficiency of the pump. j

Ad 'acent to the screw-outlet 5 is a fixed director 23, which may be in one part with the casing as herein shown, or which may be separate and secured in the casing, as may be convenient. The objectof this fixed director -is to direct the fluid gradually toward the main punsp outlet, which objectis herein accomplished with little shock or whirling, thereby saving some energy. This intat-ively within said lcreasing gradually increase o-f the capacity of said' ventionis not limited to the use of a director of the exact sha e as herein shown, or of the device shown Ilierein for reducing the velocity of the fluid adjacent the screw-outlet. i

There are two spiral blades shown in the drawings, but this invention is not limited in this respect and it is obvious that one or more spiral blades can be used; and the number of blades'used should increase with the diameter of the screw and with the pressure against which the pump operates.

Whenever the expression spiral blade occurs in this application, it signifies a blade of oblique shape and gradually curved from the screw-inlet toward the screw-outlet. The expression screw VVsignifies a body having one or more spiral blades, which blades extend in the direction from the screw-inlet toward the screw-outlet in a peripheral and substantially axial direction.

A screw-wheel, as understood in this application, may be a screw with or without a rotating outer ring.

l claim herein, of some of the characteristics, only t-he specific-construction, these same characteristics ,being claimed more broadly in my Patent No. 872,361, dated December 3, 1907.

Having thus claim: j

l. A screw pump, a fluid inlet and fluid having a substantially spiral bla de,

described my invention, l

having a casing` with outlet, a screw wheel the outer cont-our of the main portion of said blade being substantially cylindrical, corresponding to the inner wall of the casing and said screw wheel being fitted in and mounted rocasing, the casing inin diameter internally outlet,- t-o form a gradbeyond the screw into ually enlarging annular chamber, which the fluid flows from the screw.

2. A screw pump, having a casing, with a fluid inlet and fluid outlet, a'screw wheel having a substantially spiral blade, the radial width of the main portion of said blade increasing from the screw-inlet toward the screw-outlet, the outer contour of the main portion of said blade being substantially cylindrical, corresponding to the inner wall of the casing, and said screw wheel being fitted in and mounted rotatively wit-hin said casing, the casing increasing gradually in diameter internally beyond the screw outlet, to form a gradually enlarging annular chamber, into which the fluid flows from the screw. l

3. A screw pump having a casing, with a fluid inlet and lfluid outlet, a screw wheel, having a substantially spiral blade, the pitch of said blade increasing from the screwinlet toward the screw-outlet, the outer contour ofy the main portion of said blade being substantially cylindrical, corresponding to the inner wall of the casing, and said screw wheel being fitted in and mounted rotatively within said casing, th/eJ casing in- `creasing gradually in diameter internally beyond the screw-outlet, to form a gradually enlarging annular chamber, into which the fluid flows from the screw. Y l

f4. A screw pump, having a casing with a' fluid inlet and fluid out-let, a screw wheel,

rhavingva substantially spiral blade, the radial widt-h and the pitch of said blade increasing from the screw-inlet toward the vscrew-outlet, the outer contourof the main portion of said blade, being substantially cylindrical, corresponding to the inner wall of the casing, and said screw wheel being fitted in and mounted .rotatively within said casing, the casing increasing gradually in diameter internally beyond thekscrew-outlet, to form a gradually enlarging annular chamber, into which the fluid flows from the screw. l

5. A screw pump, having a casing with a fluid inlet and fluid outlet, a screw wheel,

having a substantially spiral blade, the capacity of the screw increasing from the screw-inlet Ytoward4 vthe screw-outle t,. the outer contour ofthe main portion of said blade being substantiallycylindrical, corresponding ,to the inner wall of the casing, a'nd said screw wheel beingfitted in and mounted rotativ'ely within said casing, the

casing increasing gradually in diameter internally beyond the screw-outlet, to form a gradually enlarging annular chamber, into which the fluid flows from the screw.

6. In a device' for the purpose set forth,

a casing with a fluid inlet and fluid outlet,l

a screw wheel mounted rotatively within said casing between the fluid inlet and fluid outlet,l said screw wheel having a substantially spiral blade, the Y,pitch and the full `radial width of said blade increasing from lthe' screw inlet toward the screw outlet, and means for gradually reducing the velocity of the fluid, adjacent to the screw outlet.

8. A screw pump,-having a casing withl a fluid inlet and vfluid outlet, a screw wheel, having a substantially spiral blade, which gradually 'increases to its full radial width from one end 'toward the main port1on of' the screw, the outer contour of said blade at its main portion being substantially cylindrical, corresponding to the inner wall of' the casing, and said screw wheel being fitted in and mounted rotatively within said-casing, the casing increasing gradually in diameter beyond the screw outlet, 'to form a vgradually enlarging annular chamber, into which the fluid flows from the screw.

9. A screw pump, havingva casing with a fluid inlet and fluid outlet, a screw wheel, having a `substantially spiral blade, which gradually increases to its full radial width from each end toward the main middle portion of the screw, the outer contour of said blade at its main middle portion being substantially cylindrical,-corresponding to the inner wall of the casing, and said screw wheel being fitted in and mounted rotatively within said casing, the casing increasing gradually in diameter beyond the screw outlet, to form a gradually enlarging annular chamber, into which the fluid' ows from the screw.

l0. A screw pump, having a casing with a fluid inlet and fluid outlet, a screw wheel, having a substantially spiral blade, which gradually increases to its full radial Width from one end toward the main portion of the screw, the full radial width of said blade increasing from the screw-inlet t0- ward the screw-outlet, the outer conto-ur of said blade at its main portion being substantially cylindrical, corresponding to the inner wall of the casing, and said screw wheel being fitted in -and mounted rotatively within said casing, the casing increasing gradually in diameter beyond the screw outlet, to form a gradually enlarging annular chamber, into which the fluid flows from the screw.

11. A screw pump, having a casing with a fluid inlet and fluid outlet, a screw wheel, having a substantially spiral blade, which gradually increases to its full radial width from one end toward the main portion of the screw, thel pitch of said blade increasing from the screwfinlet toward the screw-outlet, the outer contour of said blade at its main portion being substantially cylindrii l cal, correspondingto the inner wall of the casing, and said screw wheel being fitted in .and mounted rotatively wit-hin said casing,`

the casing increasing gradually in diameter beyond the screw outlet, to form a graduallyI enlarging annular chamber, `into which the fluid flows from the screw.

12. A screw pump, havinga casing with a fluid inlet and fluid outlet, a screw wheel, having a substantially spiral blade,. which gradually increases to its full radial width from one end toward the main portion of the screw, the pitch and the full radial width of said blade .increasing from the screw inlet toward -thev screw outlet, the' outer contour of said blade at its main portion beingf substantially cylindrical, corre- -yond the screwoutlet, toform a gradually enlarging annular chamber, into which the fluid flows from the' screw. Y

V13. A screw pump, having'a casing with a fluid 'inlet and fluid outlet, a screw wheel,

having a substantially spiral blade, which gradually increases to its full radial width 'from one'end toward'the main portion of the screw, the capacity increasing from the screw yinlet toward the screw outlet, the outer contour of said blade at its main portion being substantially cylindrical, 'corresponding to the inner wall of the casing, and said screwvwheel4 being fitted in and mounted rotatively within said casing, the casing increasing" gradually in diameter beyond the screw outlet, to Aform a gradually` enlarging annular chamber, into which the fluid flows from the screw. I

14.- A screw pump, having a casing,- with a fluid inlet and fluid outlet, -a screw Wheelv having a substantially spiral blade, the

4cuter contour of the mainvportion of said vblade being substantially cylindrical, correspending to the inner wall of the casing and. said screw' wheel being fitted in and mount-4 ed rotatively within said casing, the casing increasing gradually in diameter internally beyond the screw outlet,fto form a gradually enlarging annular chamber, into which the fluid flows from the screw, and a fixed director near the fluid outlet of the casing.

1.5. A screw pump, having a casing, with a fluid inlet and fluid outlet, a screw wheel having asubstantially' spiral blade, the -iadial width of the main portionof said'bladeincreasing from the screw inlet toward the screw outlet, the outer contour of the mam portion of said blade being substantially cylindrical, corresponding to the inner. wall of the casing, and said screw .wheel being fitted in and' mounted rotatively 'within said casj ing, the casing increasing-gradually indiamete'r internally beyond the screw outlet, to form a gradually enlarging annular chamber, into which the -fluid'flows from the screw, and a fixed director near the fluid outlet 'of the casing.

16. Ascre'w pump, having a casing with a u y fluid inlet and fluid outlet, a screw wheel,

having a substantially spiral blade, the pitch of said bladev increasing from theJ screweinlet toward the screw-outlet, the

v outer contour of the 'main portion of lsaid blade being substantially cylindrical, cQrrespondingto the inuenwall of the casing, and said screw wheel being fitted in and mountedrotatively 'withinfsaid casing, the casing increasinggr'adually in diameter internally beyond the screw-outlet, to forma gradu' allyenlarging annular chamber,'into which of' the casing, and said screw wheel being e fitted in and mounted rotatively within said casing, the casing increasing gradually in diameter internally beyond the screw outlet, to form a gradually enlarging annular chamber, into which the fluid flows from the screw, and a fixed director near the fluid outlet of the casing.

18. A screw pump, having a casing with a fluid inlet and fluid outlet, a screw wheel,

having a substantiallyspiral blade, the capacity of the screw 4increasing from the screw-inlet toward the screw-outlet, the outer contour of the main portion of said blade being `substantially cylindrical, corresponding'to the inner wall of the casing, and said screw wheel being fitted in and mounted rotatively within said casing, the casing increasing gradually in' diameterinternally beyond the screw-outlet, to form a gradually enlarging annular'chamber, into which the fluid flows from thei screw, and a fixed director near the fluid outlet of the casing. i i

19. A screw pump, having a casing with a fluid inlet and fluid outlet, a screw wheel, having a substantially -spiral blade,` the vpitch-and the full vradial width of said -blade 'increasing from the screw-inlet tof ward the screw-outlet, the outer contour of the main portion ofv said blade being substantially V`cylindrical, corresponding to the inner wall ofthe casing, and said screw Vwheel'being fitted in and mounted rotatively wit-hin said casing, and adjacent to the screw outlet a fixed director.-

Q 20. vA screw pump, having a casing with a fluid inlet and fluid outlet, a screw wheel, having a substantially spiral blade, the

pitch and the full vradi'al'width of said blade increasing from the screw-inlet toward the screw-outlet, said screw wheel being fitted `in and -mounted rotatively within said casing and adjacenttothe screw-outlet a fixed director. A

@21. A device for the purpose specified, having an internal cylindrical casing with a fluid-inlet and. fluid outlet` and a screw wheel the main portion of which is of cylindrical outer contour, mounted rotatively a substantially. spiral vblade and having also al core or. body whichis conical and tapers from the screw inlet toward the :within said casing between the said fluid4 Y inlet and outlet, saidv screw wheel, having screw-outlet, the pitch of said spiral blade ying a substantially spiral blade the pitch of said spiral blade and the full radialwidth of the same'increasing from the screw-inlet toward the screw-outlet.

23. A device for the purpose specified, having a casing'with a fluid inlet and fluid outlet, and a screw-'wheel mounted rota- Atively within said casing between the said fluid inlet and outlet, said screw wheel having a substantially.' spiral blade, Athe pitch and the full radial width of said blade increasing from the screw-inlet toward the screw-outlet, and the capacity of the screwout-let being greater than the capacity of the screw-inlet. l

24. A device for the purpose set forth, having a casing with a fluid inlet and fluid outlet, and a screw-wheel mounted rotatively within said casing between said fluid inlet and outlet, said screw wheel having a substantially spiral blade, whose pitch and width increase from the screw-inlet toward the screw-outlet.

25. A device for the purpose specified, having a casing with a fluid-inlet and fluidoutlet, and va screw wheel fitted in and mounted rotatively within said casing, between the said fluid inlet and outlet, said screw wheel having a substantially vspiral blade, lthe pitch and the full radial width of said blade increasing from the screwinlet toward the screw-outlet, the outer contour of the main portion of said screw being substantially cylindrical, and the capacity of the screw outlet being greater than the capactiy of the screw inlet.

26, A device for the purpose set forth, having a casing with a fluid-inlet and fluidoutlet, and a screw wheel fitted inv and mounted rotatively within said casing between said fluidinlet and outlet, said screw wheel having a substantially spiral blade, the

' pitch and the full radial width of said blade said extended screw-body being naked and of conical outer shape and tapering in the -v direct-ion from the screw-outlet.

28. A device for the purpose specified, having a casing with a fluid-inlet and liuidoutlet, and a screw wheel mounted rotatively within said casing between the said fluidinlet and outlet, said screw wheel having a substantially spiral blade, the pitch and the full radial width of -sa'id blade increasingfrom the screw-inlet toward the screw-outlet, and said screw wheel having a core or body which extends beyond the screw-inlet, said extended screw body being naked and of conical outer shape and tapering in the direction from the screw inlet.

29. A device for the purpose specified,

v having a casing with a fluid inlet a-nd fluid outlet, and a screw wheel mounted rotatively within said casing between the said fluid-inlet and fluid-outlet, said screw wheel having a substantially spiral blade, the pitch and the full radial width of said bladeincreasing from the scr-ew-inlet toward the screw-outlet. and said screw wheel having a core or body, which extends `beyond' the screw-inlet and beyond the screw-outlet, said extended screw hifly being naked andof -conical outer shape and tapering in the di-v rectio-n from the screw-inlet and in the direction from the screw-outlet.

30. A device for the purpose set forth, having a casing with a fluid inletand fluidoutlet, and a screw wheel mounted rotatively within said casing between said iiuid inlet and outlet, said screw wheel having a substantially spiral blade, Vthe pitch and the full radial width of said blade increasing from the screw inlet toward the screw outlet, the outer contour of the main portion of said screw being substantially cylindrical, and adjacent to one screw end an annular space, which increases gradually in capacity in the direction from the screw.

' 31. A device for the purpose set forth,

havinga casing with a fluid inlet and fluidv outlet, and a screw wheel mounted rotatively within said casing between said fluid inlet and fluid outlet, said screw wheel having a substantially spiral blade, the pitch, and the full radial width of saidblade increasing from the screw inlet toward t-he screw outlet, the outer contour of the main portion of said screw being substantially cylindrical, adjacent to the screw inlet an annular inlet space which increases gradually in capacity in the direction from the screw-inlet, and adjacent to the screw-outlet an annular outlet space which increases gradually in capacity in the direction from the screw outlet.

32. A device for the purpose setforth, having a casing with a fluid inlet and fluid outlet, and a screw wheel mounted rotatively within said casing between said fluid inlet and outlet, said screw wheel having a substantially spiral blade, the pitch and the full from the screw-inlet toward the screw-outradial width of said blade increasing from let, and said spiral blade increasing graduthe screw-inlet toward the screw-outlet, and -ally to its full radial width from each end having adjacent to o-ne screw-end an annutoward the main middle portion of the lar space which increases gradually in cascrew.

pacity in the direction from the screw.

33. A device for the purpose set forth, having a casing with a fluid inlet and fluid outlet, and a screw wheel "mounted rotatively within said casing between said fluid inlet and outlet, said screw wheel having a substantially spiral blade, the pitch and the full radial width of said bladeincreasing from the screw-inlet toward the screw-out let, and having adjacent to the screw-inlet an annular inlet-space which increases gradually in the direction from the screw-inlet, and adjacent `to the .screw-outlet an annular outlet-space which increases gradually in the 'direction from the screw-outlet.

34. A device for the purpose specified, having a casing with a fluid inlet and fluid outlet, and a screw wheel, mounted rotatively within said casing between said fluid inletvand fluid outlet, said screw wheel having a substantially spiral blade, the pitch and the full radial width of said blade increasing from the screw-inlet toward the screw-outlet. and said spiral blade increasing gradually to its .full radial width from one end toward the main portion of the screw, the outer contour of the main portion of said screw being substantially cylindrical.

35. A device vfor the purpose specified, having a casing with a fluid inlet and fluid outlet, and a screw wheel mounted rot-atively within said casing between said fluid inlet and Hui-d outlet, saidscrew wheel having a substantially spiral blade, the pitch and the full radial width of said blade increasing from the screw-inlet toward the screw-outlet, and said spiral blade increasing gradually to its full radial width from each end toward the main middle portion of the screw, the outer contour of the main portion of said screw being substantially cylindrical.-

A devlce for the purpose specified, having a casing with a fluid inlet and fluid outlet, and a screw wheel mounted rotatively within said casing betweenA said fluid inlet and outlet, said screw wheel having a substantially spiral blade, the pitch andthe full radial width of said blade increasing n, from the screw-inlet toward the screw-outlet, and said spiral blade increasing gradually to its full radial width from one end toward the main portion of the screw.

VA device for the purpose specified, having a casing with-,a fluid inletand fluid outlet, and a screw wheel mounted rotatively "within said casing between said fluid inlet and outlet, said screw-wheel having a substantially spiral blade, the pitch and the full radial width `of said vblade increasing 38. A device for the purpose specified, having a casing with a fluid inlet and fluid outlet, and a screw wheel mounted rotatively within said casing between said fluid inlet and outlet, said screw wheel having a substantially spiral blade, which increases gradually to its full radial width from one end toward the main portion of the screw, the pitch and the full radial width of said blade increasing from the screw-inlet toward the screw-outlet, and adjacent to one end of the screw an annular space which increases gradually in capacity in the direction from the screw, the outer contour of the main portion of said screw being substantially cylindrical. 1

39. A device for the purpose specified, having a casing with a fluid inlet and fluid outlet, and a screw wheel mounted rotatively within said casing, between said fluid inlet and outlet, said screw wheel having a substantially spiral blade which increases gradually to its full radial width from each end toward the main middle portion of' the screw, the pitch and the full radial width of said blade increasing from the screw-inlet toward the screw-outlet, and adJacent to each end of thel screw an annular space which increases gradually in capacity in the direction from the screw, the outer contour of the .main portion of said screw being substantially cylindrical.

40. A device for the purpose specified, having a casing with a fluid inlet and fluid outlet, and a screw-wheel mounted rotatively within said casing between said fluid inlet and out-let, said screw wheel having a substantially spiral blade which increases gradually to its full radial width from one end toward the main portion of the screw, the pitch and theffull radial width of said blade increasing from the screw-inlet toward the screw-outlet, and'having adjacent to one end of the screw an annular space which-increases gradually incapacity in the direction froin"the screw;

41. A device for the purpose specified, having a casing with a fluid'inlet and fluid outlet, and a screw wheel mounted rotatively within said casing between said fluid inlet and outlet, said screw wheel having a subies i'io

stantially spiral blade which increases grad-v v 42. A device for the purpose specified, having a casing with a fluid inlet and fluid outlet, a shaft, a screw wheel on said shaft, and mounted rotatively within said casing between the fluid inlet and outlet thereof, said screw wheel having a substantially spiral blade and being subjected to endthrust, and means for balancing said endthrust, said means comprising a cylindrical piston-chamber open at one end to fluid under pressure and having at its opposite end a fluid outlet independent of the shaft, a piston on the screw-shaft, said piston being located in and playing loosely Wit-hin said chamber between the fluid inlet and fluid outlet, and-a valve on the shaft, said valve controlling the fluid outlet from the pistonchamber, and said valve being automatically actuated by the longitudinal movement of the screw-shaft, substantially as set forth.

43. A device for the purpose set forth, having a casing wit-h an inlet and outlet, a

. screw-shaft mounted rotatively within said casing, a screw-wheel onsaid shaft having a. substantially'spiral blade and being subjected to end-thrust,and means for balancing said end-thrust, said means comprising a cylindrical piston-chamber open'at one'end' to fluid under pressure and having at its opposite end a fluid outlet independent of the Shaft, the said screw-shaft extending axially through the piston-chamber, a` piston fitted in and mounted rotatively on said shaft within said chamber between the fluid inlet and fluid outlet thereof, means for permitting part of the fluid to escape from the fluid inlet end to the fluid outlet end of said chamber, and a valve controlling the fluid outlet from thev chamber, said valve being automatically actuated by the longitudinal movement of the shaft.

44. A device for the purpose set forth,

l having a casing with an inlet and "outlet, a

screw-wheel on a shaft and mounted rotatively within said casing, said screw Wheel having a subst-antially spiral blade and being subjected 'to end-thrust, and means for balancing said end-thrust, said means comprising a cylindrical piston-chamber, the

Said screw-shaft, extending through the pis-.

ton-chamber, a piston on the shaft and fitted 1n and ounted rotatively within said chamber, means for admitting fluid under presshaft mounted rotatively within said casing and slidable endwise, a cylindricalpistonchamber through which the shafteextends, a

piston on the shaft, said piston fitted in p eripherally and mounted rotatively within the piston-chamber, means' for admitting fluid under pressure to said chamber and at blade, the pitchand t-liefull radial width of said blade increasing from the screw-inlet toward the screw-outlet, the outer contour of the main portion of said blade being substantially cylindrical, and means for balancing the end-thrust on said screw wheel, said means comprising a balancing device which is automatically controlled by the end wise movement of'said shaft 47. In a device for the purpose set forth, a casing having a fluid inlet and fluid outlet, a screw wheel on a shaft and mounted rotatively within said casing between the fluid inlet and fluid outlet, said screw wheel having a substantially Spiral blade, the pitch and the full radial width of said blade increasing from the screw-inlet toward the screw-outlet, and means for balancing'the end-thrust on said screw wheel, said means comprising a balancing device which is automatically controlled by the endWise-movement of said shaft.

48. A device of the character described having a casing with a fluid-inlet andfluidoutlet, a shaft andra propeller wheel on said shaft, mounted rotatively within said casing and slidable endwise, a piston-chamber, through which the shaft'extends, a piston on piston-chamber, means for admitting fluid under pressure to one end of said chamber and at one side of said piston, means for permitting part of the fluid to escape to the other .end of said chamber at the opposite side of said piston, and a fluid outlet independent of the shaft from the .latter end of said chamber and controlled from the end- Wise movement of the piston.

449. A .device for the purpose specified, having a casing with a fluid-inlet and fluidoutlet, a shaft and a propeller wheel on said shaft, mounted rotatively within said casing and slidable endwise, a piston-chamber through which the shaft extends, a piston on the shaft and being mounted rotatively within the piston-chamber, means for admitting fluid under'pressure to one'end of said chamber and at one side of said piston, means for permitting part of the fluid t0 Vescape to the other end of said chamber at the opposite side ofsaid piston, land la. fluid outlet independent of the shaft from the latv surface fitted within the chamber, means for admitting fluid under pressure to one end of said chamber and at one side of said piston, means for permitting a part of the fluid to escape to the other end of said chamber y and to the opposite side of said piston, and

a fluid-outlet independent of the shaft from the latter end of said chamber, and controlled from the endwise movement of the piston.

51. A device for the purpose specified,

l having a casing with a fluid-inlet and fiuidoutlet, a shaft mounted rotatively within said casing and slidable endwise, a cylindrical piston-chamber through which the shaft extends, a piston on said shaft, said -piston being fitted in peripherally and mounted rotatively within the piston-chamber, means for admitting fluid under pressure to one end of said chamber and at one side of said piston, means for permitting a part-of the fluid to escape to the other end of said chamber and to the opposite side of said piston and a fluid-outlet independent of the sha-ft from the latterend of said chamber, said outlet being controlled by the piston through its endwise movement.

v 52. In a device for the purpose set forth, a casing with a fluid inlet and fluid outlet, al screw wheel fitted in'and mounted rotatively'within said casing, between said fluid inlet and fluid outlet, said screw wheel having a substantially spiral blade, the pitch and the full radial width of said blade increasing throughout the screw from its inlet, land means for gradually reducing the velocity of the fluid, adjacent to the screwoutlet. p

53. A device of the character described having a casing with a fluid-inlet and fluidoutlet, and a screw-wheel mounted rotatively within the casing between said fluid-inlet and fluid-outlet and having a substantially spiral blade the pitch of which increases from the screw-inlet toward 'the screw-outlet, thescreW-outlet capacity being greater than the screw-inlet capacity and the full radial width of said blade being less than one sixth part of the corresponding diameter of the outer contour of the screw.

54:.` A device of the character described having a casing with a li'uid-inlt'and fluidoutlet, and a screw-wheel having atE its main portion a substantially cylindrical outer contour, mounted rotatively in the casing between said fluid-inlet and fluid-outlet, said screw-wheel having a substantially spiral blade the pitch of which increases from the screw-inlet toward the screw-outlet, the screw-outlet capacity being greater than the screw-inlet capacity and the full radial width of said blade being less than one sixth part of the corresponding diameter of the outer contour of the screw.

55. A device of the character described having a casing with a fluid-inlet and fluidoutlet, a screw wheel mounted to turn in the casing between said fluid-outlet and fluid-inlet, said screw wheel having a substantially spiral blade, the pitch of said blade and t-he capacity of the screw increasing throughout from the screw-inlet toward the screw-outlet and the full radial width of said blade being less than one sixth part of the corresponding diameter of the outer contour of the screw. Y

56. A device of the character described having a casing with a Huid-inlet and fluidoutlet, a screw-wheel having a substantially cylindrical outer contour mounted to turn in the casing between the fluid-inlet and Huid-outlet, said screw-wheel having a substantially spiral blade, the ypitch'of said blade and the capacity of the screw increasing throughout from the screw-inlet toward the screw-outlet .and the full radial width of said blade being less than one sixthpart of the corresponding diameter of the outer conteur of the screw.`

57. A device of the character described having a casing with a fluid-inlet and fluidoutlet, a screw-wheel having at itsr main portion a substantially cylindrical outer contour mounted to turn in the casing between the fluid-inlet and Huid-outlet and having a substantially spiral blade the pitch of which increases Afrom the screw-inlet toward the screw-outlet and the full radial width of which is less than one sixth part of the corresponding diameter of the outer contour of the screw, and means for gradually reducing the velocity of the fluid adjacent to the screw-outlet.

58. A device of the character described having a casing with a fluid-inlet and fluidoutlet, and a screw-wheel mounted to turn in said casing between said fluid-inlet and` tially cylindrical outer contour mounted to turn in the casing between the fluid-inlet in the casing between the fluid-inlet and Huid-outlet and having a substantially spiral blade the pitch of said blade and the capacity of the screw increasing throughout from the screw-inlet toward the screwoutlet, and the full radial width of the blade being less than one sixth part of the c orresponding diameter 'of the outer contour of the screw, and means for -gradually reducing the velocity of the fluid adjacent to the screw-outlet.

61. A device of the character described having a casing with a fluid-inlet and fluidoutlet, and a screw-wheel mounted to turn in the casing between the fluid-inlet and Huid-outlet and having aqsubstantially spiral blade the pitch of which increases from the screw-inlet toward the screw-outlet, said screw-wheel having a core or body which extends beyond the screw-outlet, said extended screW-body-being naked and of conical outer shape and tapering from the screw-outlet, and an annular space around said tapered body, said annular space gradually increasing in capacity and in width in the direction from the screw-outlet.

62. A device of the character described having a casing with a fluid-inlet and fluidoutlet, and a screw-wheel having .a substantially cylindrical outer contour mounted to fturn in the casing between the fluid-inlet and fluid-outlet,` said scr w-wheel having a substantially spiral blade the pitch of which increases from the screw-inlet toward the screw-outlet, said screw-wheel having a core or body which extends beyond the screw-outlet, the extended screw-body being naked and of conical outer shape and tapering .from the screw-outlet, and an annular fspace around the screw-body, said annular space gradually increasing in capacity and in width in the direction from the screwoutlet.

63. A' device of the character described having a casing with a fluid-inlet and fluidoutlet, and a screw-wheel mounted to turn in the casing between the fluld-lnlet and 4fluid-outlet and having 'a substantially vvspiral lblade the pitch of which increases vnular space which increases from the screw-inlet toward the screw-outlet, and said screw-wheel having a core or body extended beyond the screw-inlet, said extended screw-body being naked and of conical outer contour and tapering in the direction from the screw-inlet.

64:. A device of the character described having a casing with a fluid-inlet and fluidoutlet, and a screw-wheel having a s ubstantially cylindrical outer contour'mounted to turn in the casing between the-fluid-inlet and fluid-outlet and having a substantially spiral blade the pitch of which increases from the screw-inlet toward the screw-outlet, and said screw-wheel having a corel or body which extends beyond the screw-inlet7 said extended screw-body being naked and of conical louter contour and tapering in the direction from the screw-inlet.

65. :A device of the character described having a casing wit-h a fluid-inlet and fluidoutlet, and a screw-wheel mounted to turn in the casing i between the fluid-inlet and fluid-outlet and having a substantially spiral blade the pitch of which increases from the screw-inlet toward the screw-outlet, and adjacent to the screw-outlet an annular outlet space which gradually increases in capacity and in width in the direction from the screw-outlet.

66. A device of the character described having a casing with a fluid-outlet and fluidinlet, and a screw-wheel having a substantially cylindrical outer contour mounted to turn in the casing between the fluid-inlet and fluid-outlet and having a substantially spiral blade, the pitch of which increases from the screw-inlet toward the screw-outlet7 and adjacent to the screw-outlet an annular outlet space which gradually increases in capacity and in width in the direction from the screw-outlet.

67. A deviceof' the character described having a casing with a fluid-inlet and fluidoutlet, and a screw-wheel mounted to turn in the casing between the fluid-inlet and fluid-outlet and having a substantially spiral blade the pitch of which increases from the screw-inlet toward the screw-outlet, and adjacent to one screw-endl an annular space which increases gradually in capacity and in width in the direction from the screw.

68. A device of the kcharacter described having a casingl with a'fluid-inlet and fluidoutlet, and a screw-wheel having a substantially cylindrical outer contour mounted to turn in the casing between the fluid-inlet and fluid-outlet and having a substantially u spiralv blade the pitch of which increases from the screw-inlet toward the screw-outlet,and adjacentl to one screw-end an ann gradually in capacity and 1n wldth 1n the dlrection from the screw.

69. iA Jdevice of' the character described having a casing with a fluid-inlet and fluidoutlet, and a screw-wheel mounted to turn in the casing between said fluid-inlet and fluid-outlet and having a substantially spiral blade the pitch of which increases from the screw-inlet toward the screw-outlet, and adjacent to the screw-inlet an annular inlet space which increases gradually in capacity and Ain width in the direction from the screw-inlet, and adjacent to thel screw-outlet an annular outlet space which increases gradually in capacity and in width in the direction from the screw-outlet.

70. A device of the character described having a casing witha fluid-inlet and fluidoutlet, and a screw-wheel having a substantially cylindrical outer contourv mounted to turn in the casing between the fluid-inlet and fluid-outlet and having a substantially spiral blade the pitch of which increases from the screw-inlet toward the screw-outlet, adjacent to the screw-inlet an annular space increasing gradually in capacity and width in the direction from the screw-inlet., and adjacent to the screw-outlet, an annular outlet space increasing gradually in capacity andwidth in the direction from the screw-outlet.

71. A device yof the character described having a casing with a fluid-inlet and fluidout-let, and a screw-wheel mounted to turn in the casing between the fluid-inlet and fluid-outlet and having a substantially spiral blade the pitchof which increases from the screw-inlet toward the screw-outlet, and said spiral blade gradually increasing to its full radial widthy from one end toward the main portion of the screw.

72. A device of the character described having avcasing with a fluid-inlet and fluidoutlet, and a screw-wheel having a substantially cylindrical vouter contour mounted to turn in the casing between the fluid-inlet and fluid-outlet and having a substantially spiral blade the pitch of which increases from the screw-inlet toward the screw-outlet, and said.spiral blade gradually increasing to its full radial width from one end toward the main portion 'of the screw.

73. A device of the character described having a casing with a fluid-inlet and fluidoutlet, and a screw-wheel mounted to turn in the casing betweenthe fluid-inlet and fluid-outlet. and having a substantially spiral blade the pitch of which increases from the screw-inlet toward the screw-outlet, and said spiral blade gradually increasing to its full radial width from each end toward the main middle portion of the screw. A

74. A device of the character described having a casing with a fluid-inlet and fluidoutlet, and a screw-wheel having a substantiallycylindrical outer contour mounted to turn in the casing between the fluid-inlet and fluid-outlet and having a substantiall' spiral blade the pitch of which increases from the screw-inlet toward the screw-outlet, and said spiral blade gradually increasing toits full radial width from eachend toward the main middle portion of' the screw.

75. A device of the character described having a casing with a fluid-inlet and fluidoutlet, and a screw-wheel mounted to turn in the casing between the fluid-inlet and fluid-outlet and having a substantially spiral blade which gradually increases to its full radial width from one end toward the main portion of the screw and the pitch of which increases from the screw-inlet toward the screw-outlet, and adjacent to one screw-end an annular space increasing gradually in capacity and width in the direction from the screw.

763 A device of the character described having a casing with a Huid-inlet and fluidoutlet, and a screw-wheel having a substantially cylindrical outer contour mounted to turn in the casing between said inlet and outlet and having a substantially spiral blade which gradually increases to its full radial width from one end toward the main portion of the screw and the pitch of which increases from the screw-inlet toward the screw-outlet, and adjacent to the screw-end an annular space which increases gradually in capacity and width in the direction from y the screw.

77. A device of the character described having a casing with a fluid-inlet and fluidoutlet, and a screw-wheel mounted to turn in the casing between said inlet and outlet and having a substantially spiral blade which increases gradually to its full radial width from each end toward the main middle portion of the screw andthe pitch of which increases from the screw-inlet toward the screw-outlet, and adjacent to each screwend an annular space increasing graduallyv in capacity and width in the direction from the screw.

78. A device of the character described having a casing with a fluid-inlet and fluidoutlet, and a screw-wheel having a substantially cylindrical outer contour mounted to turn in the casing between said inlet and outlet and having a substantially spiral blade which increases gradually to its full radialwidth from each end toward the main middle portion of the screw and the pitch of which increases from the screw-inlet toward the screw-outlet,I and adjacent to each screwy end an annular space increasing gradually in capacity and width in the direction from the screw.

79. A device of the character described having a casing with a fluid-inlet and fluidoutlet,; and a screw-wheel mounted to turn in the casing between said inlet and outlet and having a substantially spiral blade which increases gradually to its -full radial width from one end toward the main portion of the screw and the pitch of which increases' from the .screw-inlet toward the screw-outlet, and means for gradually reducing the velocity of the fluid adjacent to the screw-outlet.

80. A' device of the character adescribed having a casing with a fluid-outlet and fluidinlet, and a screw-wheel with a substantially cylindrical outer contour mounted to turn in the casing between said inlet and outlet and having a substant-ially spiral bladewhich gradually increases to its full radial width from one end toward' the main portion of the screw and the pitch of which increases from the screw-inlet toward the screw-outlet, and means for gradually reducing the velocity of the fluid adjacent to the screw-outlet.

8l. A device of the character described having a casing with `a fluid-inlet and fluidoutlet, and a screw-wheel mounted to turn in Athe casing between said inlet and outlet and having a substantially spiral blade which increases gradually to its full radial width from each end toward the main middlev portion of the'screw and the pitch of which increases from the screw-inlet toward the screw-outlet, and means Jfor radually reducing the velocity of the flui adjacent to the screw-outlet.

82. A device of the character described having a casing with a fluid-inlet and Huidoutlet, and Ma screw-wheel with a substantially cylindrical outer contour mounted to turn in the casing between the fluid-inlet f and fluid-outlet and having a substantially spiral blade which increases gradually to its full radial width from each end toward the main portioln of the screw and the pitch of which increases from the screw-inlet toward the screw-outlet, and means for gradually reducing the velocity of the fluid adjacent to the screw-outlet.

83. n a device for the purpose set forth, a casing with a fluid inlet and fluid outlet, a screw wheel with its main portion of sub# stantially cylindrical outer' contour mounted rotatively within said casing between the Huid inlet and fluid outlet, said screw wheel having a substantially spiral blade, the pitch and the full radial width ot said blade increasing from the screw inlet toward the screw outlet, and means for gradually reducing the velocity of the fluid, adjacent to the screw outlet.

In witness whereof I have hereunto signed* my name this 18th day of September, 1903,v`

in the presence of two subscribing witnesses.

FRANZ/MARBURG, J R.

Witnesses: l

y BENJAMIN H. HoL'r, WILLIAM J. FIRTH.

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