US1377210A - Pump - Google Patents

Pump Download PDF

Info

Publication number
US1377210A
US1377210A US409074A US40907420A US1377210A US 1377210 A US1377210 A US 1377210A US 409074 A US409074 A US 409074A US 40907420 A US40907420 A US 40907420A US 1377210 A US1377210 A US 1377210A
Authority
US
United States
Prior art keywords
vanes
rotor
casing
runway
ring
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US409074A
Inventor
Harvey B Lindsay
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to US409074A priority Critical patent/US1377210A/en
Application granted granted Critical
Publication of US1377210A publication Critical patent/US1377210A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04CROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C14/00Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations
    • F04C14/06Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations specially adapted for stopping, starting, idling or no-load operation
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04CROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2/00Rotary-piston machines or pumps
    • F04C2/30Rotary-piston machines or pumps having the characteristics covered by two or more groups F04C2/02, F04C2/08, F04C2/22, F04C2/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members
    • F04C2/34Rotary-piston machines or pumps having the characteristics covered by two or more groups F04C2/02, F04C2/08, F04C2/22, F04C2/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in groups F04C2/08 or F04C2/22 and relative reciprocation between the co-operating members
    • F04C2/344Rotary-piston machines or pumps having the characteristics covered by two or more groups F04C2/02, F04C2/08, F04C2/22, F04C2/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in groups F04C2/08 or F04C2/22 and relative reciprocation between the co-operating members with vanes reciprocating with respect to the inner member
    • F04C2/3448Rotary-piston machines or pumps having the characteristics covered by two or more groups F04C2/02, F04C2/08, F04C2/22, F04C2/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in groups F04C2/08 or F04C2/22 and relative reciprocation between the co-operating members with vanes reciprocating with respect to the inner member with axially movable vanes

Definitions

  • This invention relates to certain new and useful improvements in pumps, and among other objects the invention has to simplif the structure and improve the vane contro
  • the invention is also applicable to lclutches, brakes, or the like or similar devices ein loying rotary blades moving in a bodyof liquid.
  • the invention further resides in a construction wherein the vanes are movable in an axial 'direction so that their control isy facilitated and the action of centrifugal force against the control is avoided.
  • Figure 1 is a transverse section through the improved liquid clutch, brake or pump structure
  • Fig. 2 is a side elevation thereof
  • Fig. 3 is a similar view of a piimppem ⁇ bodying the improvements
  • Fi 4 is a like view of the invention as ap lied to a clutch or brake; 0
  • a ig. 5 is a transverse section through a modified construction
  • Fig. 6 is a detailed elevation of the vanecontrolling ring incorporated therein;
  • Fi 7 is a transverse section of the modified4 crm taken at right angles to the plane of section for Fig. 5
  • Fig. 8 is an elevation of the rotor per se
  • Fig. 9 is a transverse section through a further modification
  • Fig. 10 is a similar view of .the rotor therefor taken on line lQe-lO of F1 11.
  • Fig. 11 is a side elevation of t e rotor
  • Fig. 12 is an inside view of one of the sections of the casing depicted 1n Fig. 9.
  • the casing 1 is circumferentially divided into two sections eachhaving in its radial face a concentric channel or runway 2 whose plane is inclined relative to the diametral plane of the casing whereby the channel will gradually rise to its 'reatest hei ht for one-half ofA the circum erence ail then gradually descend for the second half of the circumference, the channelway on one side of the Casin being arranged in staggered or reverse re ation to the channelway on the opposite side whereby the points of greatest delpth will occur diametrically opposite-each ot er.
  • a rotor 3 is fixed on the shaft 4, journaled in bearin s 5 of the casing, and is provided with radial slots in which the vanes 6 are mounted to slide in an axial direction.
  • each runway 2 is equipped with two conduits 8, one connecting the openin s 7 on one side ofthe shallowest portion o the runway an-d the other disposed on the opposite side thereof, thereby providing an inlet and an outlet for the rel spective sides of the pump.
  • the clutch In the clutch.
  • the single conduit 8 provides a continuous bypass about the shallow portion or point of greatest resistance in the runway so that the rotor-may freely rotate within the casing.
  • Ad'ustable means are provided for varying t e resistance .to the passage ofthe iiuid through the conduit, the same prefervsage o shown) slidable on the shaft. If the valve is completely closed, the fluid will be prei ventedV from by-passing and consequently the casing and ⁇ rotor will be locked against vrelative movement.
  • a positive mechanical lever (not shown) may be further provided. More or less opening of the valve will increase or decrease the relative movement between the casing and shaft.
  • the rotorA 11 is mounted in the casing 12- which has only one runway or channel 13, the vanes 14 being slidable in an axial manner thereinto by means of a guide ⁇ ring 15.
  • This vring is pivoted on ,the opposite side of the rotor to the casing by means of a bracket 16, fixed to the cover 17 thereof, and a screw 18 countersunk into. thel ring as shown.
  • the cover is spaced from the rotor to provide a large compartment 19 for the ring, andinto this compartment extend the rear ends of the vanes the same havin inwardl apenin slots or seats 20 vfor sli ably em racing t e ring.
  • Said ⁇ ring is provided with a pair of parallel, chorda'l arms 21 between w ich and the intercepted arcs are pivotally mounted the inner ends of rods 22, as by ivot bolts 23, and these rods slidably exten through stuiling boxes 2l, on the cover 17, and 'have their outer ends secured to the outer ends of radial arms 25, the latter extending from a collar 26.
  • This collar, together with a second collar 27, is carried on a sleeve 28 which is slidable upon the drive shaft 29 by means of a lever 30 whose forked end straddles and is pivotally attached to the collar 27.
  • a fulcrum support 31 for the vane-controlling lever 30 is fixed to the cover whereb the vanes, their ring and the vane control ing mechanism can be removed as a unit with the cover.
  • the ulcrum is supported on an independent fixed frame (not shown).
  • the casing is preferably divided circumferentially linto a pair of sections each formed with an axially extending, annular flange 38, which flange is concentric within the casing, but eccentric relative to the shaft, and is spaced from the'opposing flange to define therewith an annularspace through which the web of the rotolr 36 extends.
  • the ianges 38 define an annular channel or runway for the vanes which, by reason of the eccentric disposal of the shaft, are successively rojected and retracted from the radial s ots 35, and the fluid is driven ahead of the vanes in the arcuate chamber 39 and discharged throu hthe lateral orifices 40.
  • the vanes are automatically shifted into and out of ⁇ theizid channels by the walls thereof, while in Fig. 5 the vanes are under manual control and can be withdrawn entirely from the compression 'or fluid chambers.
  • the vanes are double acting at each end, or the may operate in a single capacity only.
  • two or more arcuate, inclined channe s,on each end, havin respective points of greatest depth and sA allowness at different circumferential positions, and arranged concentrically, ma be required, which, in turn will require' a ouble set of vanes.
  • the casings are rovided with filling openings 41 for supp ying the liquidto the interior mechanism, in an obvious manner.
  • a casin a rotor therein, .vanes movable in an axia direction on the rotor, said casing having a runway for the vanes, and means for varying the degree of movement of the vanes intothe runway.
  • a casin a rotor therein, vanes movable in an axial-direction on the rotor, said or certain pur oses f casing having a runway for the vanes, and
  • a casing having a runway-for the vanes, and means Afor varying the depth at which the l vanes are to operate inthe runway, said means including a vane-guidin member movable toward and from the side of the rotor.
  • a casing having a runway, a rotor in the casing having atransverse slot, a
  • vane slidable in the slot for projection into the runway and movable guide means for y projecting the vane into the runway.
  • a casing having a runwa a rotor in the casing having a transverse s ot, a vane sl'idable in theslot for projection into the runwayya guide member pivoted in the casing at one vside for swinging inwardly t0,-v
  • a casing having a runway, a rotor slidablein the slotfor projection into the runway, a guide ring pivoted to the casing and slidably connected to the vanes whereby the latter may revolve about the ring, and means for adjusting the ring angularly to accord the vanes a corresponding angular path of movement in therunway.
  • a casingV having a'runway, a rotor in .the casing having a transverse slot, a vane slidable in the slot for projection-into the runway, a uide ring pivoted to the casing and slida ly connected to the vane whereby the' latter may revolve around th.
  • a casing havin a runway on the end thereof, the end wa 1 of which runway is inclined from the axial -perpendicular to the end that a gradual varlation shall exist in the distance from said end wall of said runway and the face of a rotor revoluble within said casing, said rotor carrying means obstructing said runway.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Rotary Pumps (AREA)

Description

H. B. LINDSAY.
PUMP. APPLlcATloN man sans. 1920.
Patented May 10, 1921.
4 SHEETS-SHEET 1.
H. B.-L|NDSAY.
PUMP. (APPLICATION FILED SEPT. 9. 1920.
Patented May 10, 1921;
- 4 SHEETS-SHEET 2.
- Eii.,
H HIM,74
H. LINDSAY.
- PUMP.
Y APPLICATION FILED SEPT. 9, `|920. '1,377,210 Patented May 10, 1921.
4 SHEETS-SHEET 3.
H. B. LINDSAY.
PUMP.
APPLICATION mp0 SEPT. 9. 1920.
'1377,21 0 Patented May1o,1921.
4 SHEETS-SHEET 4.
Eml-
IuNi'ri-:D STATES PATENT carica.
HARVEY' TB. LINDSAY, 0F OAKLAND, CALIFORNIA.
PUMP.
Specification of Letters Patent.
Patented May 10, 192,1.
Application nled September 9, 1920. Serial No. 409,074.
new and useful Improvements in Pumps;l
and I do declare the following to be a full,
- clear, and exact description of the invention,
such as will enable ot ers skilled in the art to which it appertains to make and use the same.
-This invention relates to certain new and useful improvements in pumps, and among other objects the invention has to simplif the structure and improve the vane contro The invention is also applicable to lclutches, brakes, or the like or similar devices ein loying rotary blades moving in a bodyof liquid.
The invention further resides in a construction wherein the vanes are movable in an axial 'direction so that their control isy facilitated and the action of centrifugal force against the control is avoided.
Further, the invention resides in a coinpact structure entirely lacking of springs and embodying but few moving parts., and also in the features of construction and the arrangements and combinations of parts hereinafter described and claimed, reference being had to the accompanying drawings wherein:
Figure 1 is a transverse section through the improved liquid clutch, brake or pump structure;
Fig. 2 is a side elevation thereof;
Fig. 3 is a similar view of a piimppem` bodying the improvements;
Fi 4 is a like view of the invention as ap lied to a clutch or brake; 0
a ig. 5 is a transverse section through a modified construction;
Fig. 6 is a detailed elevation of the vanecontrolling ring incorporated therein;
Fi 7 is a transverse section of the modified4 crm taken at right angles to the plane of section for Fig. 5
Fig. 8 is an elevation of the rotor per se;
Fig. 9 is a transverse section through a further modification;
Fig. 10 is a similar view of .the rotor therefor taken on line lQe-lO of F1 11.
Fig. 11 is a side elevation of t e rotor; and
Fig. 12 is an inside view of one of the sections of the casing depicted 1n Fig. 9.
In the form depicted in Figs. 1 through i4, the casing 1 is circumferentially divided into two sections eachhaving in its radial face a concentric channel or runway 2 whose plane is inclined relative to the diametral plane of the casing whereby the channel will gradually rise to its 'reatest hei ht for one-half ofA the circum erence ail then gradually descend for the second half of the circumference, the channelway on one side of the Casin being arranged in staggered or reverse re ation to the channelway on the opposite side whereby the points of greatest delpth will occur diametrically opposite-each ot er.
A rotor 3 is fixed on the shaft 4, journaled in bearin s 5 of the casing, and is provided with radial slots in which the vanes 6 are mounted to slide in an axial direction.
Consequently, upon rotating the shaft relative to the casing the bottom of both channels will engage the opposite ends of the Varies and theV gradual rise of one bottom will effect shifting of the vane into the opposite channel. Therefore, the vanes will be alternately shifted from one side of the rotor to the other and thus drive or impel the fluid in each channel in advance thereof and out through the ports provided unless the flow is impeded or restricted. When the depicted in Fig. 3 each runway 2 is equipped with two conduits 8, one connecting the openin s 7 on one side ofthe shallowest portion o the runway an-d the other disposed on the opposite side thereof, thereby providing an inlet and an outlet for the rel spective sides of the pump. In the clutch.
and brake embodiment as in Fig. 4 the single conduit 8 provides a continuous bypass about the shallow portion or point of greatest resistance in the runway so that the rotor-may freely rotate within the casing. Ad'ustable means are provided for varying t e resistance .to the passage ofthe iiuid through the conduit, the same prefervsage o shown) slidable on the shaft. If the valve is completely closed, the fluid will be prei ventedV from by-passing and consequently the casing and` rotor will be locked against vrelative movement. A positive mechanical lever (not shown) may be further provided. More or less opening of the valve will increase or decrease the relative movement between the casing and shaft.
In the embodiment shown in Figs. 5 through 8, the rotorA 11 is mounted in the casing 12- which has only one runway or channel 13, the vanes 14 being slidable in an axial manner thereinto by means of a guide `ring 15. This vring is pivoted on ,the opposite side of the rotor to the casing by means of a bracket 16, fixed to the cover 17 thereof, and a screw 18 countersunk into. thel ring as shown. The cover is spaced from the rotor to provide a large compartment 19 for the ring, andinto this compartment extend the rear ends of the vanes the same havin inwardl apenin slots or seats 20 vfor sli ably em racing t e ring. Said `ring is provided with a pair of parallel, chorda'l arms 21 between w ich and the intercepted arcs are pivotally mounted the inner ends of rods 22, as by ivot bolts 23, and these rods slidably exten through stuiling boxes 2l, on the cover 17, and 'have their outer ends secured to the outer ends of radial arms 25, the latter extending from a collar 26. This collar, together with a second collar 27, is carried on a sleeve 28 which is slidable upon the drive shaft 29 by means of a lever 30 whose forked end straddles and is pivotally attached to the collar 27. In the brake embodiment, a fulcrum support 31 for the vane-controlling lever 30 is fixed to the cover whereb the vanes, their ring and the vane control ing mechanism can be removed as a unit with the cover. When the device is em loyed as a clutch wherein the casing itsel revolves, the ulcrum is supported on an independent fixed frame (not shown).
v Obviously, swinging the lever handle to the left (Fig. 5)-, the ring 15 will be swung inwardly about the pivot 18 to assume a position upwardly inclined from its pivot and to the ri ht, the innermost inclination parvertical will withdraw the vanes 'and accordingly decrease the resistance to the pasthe vanes. In their rotary movement'the vanes are carried by the rotor about the guide ring 15, said ring being held from a rotary movement relative to the casing.
" V-With the vanes fullyy withdrawn the ring will be disposed parallel to the cover where it is engaged by an abutment 32 projecting from the cover into the path of a stolp lug A33 on said ring. When the device is operative as a liquid` clutch the base of the runway 1s uninterrupted by openings whereas for a pump these openings are provi-ded in a manner similar to the arrangement depicted in Fig. 2, or they may be provided in which are slidable in a radial direction, the
same being mounted in the radial slots 35 of a rotor 36 an-d operable within the cylindrical casin 37 whose side or end walls are flat throng out and provided with shaft bearings which are eccentrically disposed. l
The casing is preferably divided circumferentially linto a pair of sections each formed with an axially extending, annular flange 38, which flange is concentric within the casing, but eccentric relative to the shaft, and is spaced from the'opposing flange to define therewith an annularspace through which the web of the rotolr 36 extends. The ianges 38 define an annular channel or runway for the vanes which, by reason of the eccentric disposal of the shaft, are successively rojected and retracted from the radial s ots 35, and the fluid is driven ahead of the vanes in the arcuate chamber 39 and discharged throu hthe lateral orifices 40.
ln this latter crib, as is also true of the embodiment exemplified in Figs. 1 to 4, inclusive, the vanes are automatically shifted into and out of\the luid channels by the walls thereof, while in Fig. 5 the vanes are under manual control and can be withdrawn entirely from the compression 'or fluid chambers. The vanes are double acting at each end, or the may operate in a single capacity only. two or more arcuate, inclined channe s,on each end, havin respective points of greatest depth and sA allowness at different circumferential positions, and arranged concentrically, ma be required, which, in turn will require' a ouble set of vanes. The casings are rovided with filling openings 41 for supp ying the liquidto the interior mechanism, in an obvious manner.
What is claimed is:
1. In a mechanism of the character described,I a cas1ng,a.rotor therein, vanes mov` able in an axial direction'on the rotor, and means for adjusting the vanes on the rotor.
2. In a mechanism of the character described, a casin a rotor therein, .vanes movable in an axia direction on the rotor, said casing having a runway for the vanes, and means for varying the degree of movement of the vanes intothe runway.
' 3. In a mechanism of the character described, a casin a rotor therein, vanes movable in an axial-direction on the rotor, said or certain pur oses f casing having a runway for the vanes, and
means for varying the ydepth at which the `vanes are to operate in the runway, said member.
means including a vane-guidin movable toward and from the slde of the rotor.
4. In a mechanism of the character de-v scrlbed, a casing, a rotor therein, vanes movable in an axial direction on the rotor, said casing having a runway-for the vanes, and means Afor varying the depth at which the l vanes are to operate inthe runway, said means including a vane-guidin member movable toward and from the side of the rotor.
`5. In a mechanism of the character described, a casing having a runway, a rotor in the casing having atransverse slot, a
vane slidable in the slot for projection into the runway and movable guide means for y projecting the vane into the runway.
6. Inl a mechanism of the character described, a casing having a runwa a rotor in the casing having a transverse s ot, a vane sl'idable in theslot for projection into the runwayya guide member pivoted in the casing at one vside for swinging inwardly t0,-v
ward the rotor at the op osite side, said vane slidably embracing t e periphery of the guide member, and means for adjusting the position of the guide member to vary the vmovement: of the vane into the runway.
7. In a mechanism of the character descrlbed, a casing having a runway, a rotor slidablein the slotfor projection into the runway, a guide ring pivoted to the casing and slidably connected to the vanes whereby the latter may revolve about the ring, and means for adjusting the ring angularly to accord the vanes a corresponding angular path of movement in therunway.
8. In mechanism of the character dcscribed, a casingV having a'runway, a rotor in .the casing having a transverse slot, a vane slidable in the slot for projection-into the runway, a uide ring pivoted to the casing and slida ly connected to the vane whereby the' latter may revolve around th.
- ring, and means for adjusting the ring angularly to accord the vane a corresponding angular path of movement inthe runway, said runway provided with intake and dischar ev orifices;
9. n al mechanism of the character described, a casing havin a runway on the end thereof, the end wa 1 of which runway is inclined from the axial -perpendicular to the end that a gradual varlation shall exist in the distance from said end wall of said runway and the face of a rotor revoluble within said casing, said rotor carrying means obstructing said runway.
In testimony whereof I affix m HARVEY B. LI
si nature. l D AY.
Witnesses:
C. SETON LINDSAY, JAMES M. HUDNUT.
US409074A 1920-09-09 1920-09-09 Pump Expired - Lifetime US1377210A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US409074A US1377210A (en) 1920-09-09 1920-09-09 Pump

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US409074A US1377210A (en) 1920-09-09 1920-09-09 Pump

Publications (1)

Publication Number Publication Date
US1377210A true US1377210A (en) 1921-05-10

Family

ID=23618949

Family Applications (1)

Application Number Title Priority Date Filing Date
US409074A Expired - Lifetime US1377210A (en) 1920-09-09 1920-09-09 Pump

Country Status (1)

Country Link
US (1) US1377210A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2418354A1 (en) * 1978-02-23 1979-09-21 Bosch Gmbh Robert ROTARY DISPLACEMENT VANE PUMP
FR2590932A1 (en) * 1985-12-02 1987-06-05 Valibus Alain Volumetric device and improvements to rotating machines with vanes or walls
US20050214155A1 (en) * 2004-03-23 2005-09-29 Brother Kogyo Kabushiki Kaisha Pump and ink jet printer mounting the pump
US20170167488A1 (en) * 2015-12-10 2017-06-15 Albert's Generator Services Inc. Apparatus for driving fluid having a rotating cam and rocker arm

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2418354A1 (en) * 1978-02-23 1979-09-21 Bosch Gmbh Robert ROTARY DISPLACEMENT VANE PUMP
FR2590932A1 (en) * 1985-12-02 1987-06-05 Valibus Alain Volumetric device and improvements to rotating machines with vanes or walls
US20050214155A1 (en) * 2004-03-23 2005-09-29 Brother Kogyo Kabushiki Kaisha Pump and ink jet printer mounting the pump
US7258535B2 (en) * 2004-03-23 2007-08-21 Brother Kogyo Kabushiki Kaisha Sealing features for a pump and ink jet printer mounting the pump
US20170167488A1 (en) * 2015-12-10 2017-06-15 Albert's Generator Services Inc. Apparatus for driving fluid having a rotating cam and rocker arm
US9964109B2 (en) * 2015-12-10 2018-05-08 Albert's Generator Services Inc. Apparatus for driving fluid having a rotating cam and rocker arm

Similar Documents

Publication Publication Date Title
US2393223A (en) Hydraulic motor
US1996875A (en) Fluid motor and pump
US1495526A (en) Rotary prime mover, motor, compressor, pump, and the like
US1377210A (en) Pump
US1460487A (en) Rotary compressor, expander, motor, and pump
US1567912A (en) Hydraulic clutch
US1376397A (en) Rotary engine
US2045851A (en) Pump
US2543603A (en) Fluid operated variable-speed power-transmitting device
US2370934A (en) Fluid pressure machine
US1516053A (en) Pump
US2293369A (en) Constant delivery vane pump
US1037655A (en) Rotary engine.
US979272A (en) Combined clutch and multiple transmission.
US2513447A (en) Rotary pump or motor
US1398788A (en) Rotary pump or motor
US2413935A (en) Pump
US1786435A (en) Centrifugal pump
US1459637A (en) Rotary machine
US2336225A (en) Rotary engine
US1945220A (en) Rotary pump machine
US2321190A (en) Rotary pump
US2466622A (en) Hydraulic axial vane pump or motor
US1659753A (en) Fluid power-transmitting mechanism
US1153873A (en) Rotary pump.