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Publication numberUS3502028 A
Publication typeGrant
Publication dateMar 24, 1970
Filing dateFeb 8, 1968
Priority dateFeb 8, 1968
Publication numberUS 3502028 A, US 3502028A, US-A-3502028, US3502028 A, US3502028A
InventorsRoy F Cooper
Original AssigneeSargent Industries
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Hydraulic motor and pump
US 3502028 A
Abstract  available in
Images(3)
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Claims  available in
Description  (OCR text may contain errors)

March 24, 1970 R. F. COOPER HYDRAULIC MOTOR AND PUMP I5 Sheets-Shea?l 1 Filed Feb. 8. 1968 R. F. COOPER HYDRAULIC MOTOR AND PUMP March 24, 1970 5 Sheets-Sheet 2 Filed Feb. 8'. 1968 su.. @Q

March 24, 1970 R. F. COOPER HYDRAULIC MOTGR AND PUMP 15 Sheets-Sheet 5 Filed Feb. 8, 1968 United States Patent 3,502,028 HYDRAULIC MOTUR AND PUMP Roy F. Cooper, Huntington Park, Calif., assigner to Sargent Industries (Oil Well Equipment Division), Huntington Park, Calif., a corporation of Delaware Filed Feb. 8, 1968, Ser. No. 704,104 Int. Cl. F04b 47/00; F01b 7/18 U.S. CL 103-46 9 Claims ABSTRACT 0F THE DISCLOSURE This invention relates to apparatus for pumping wells, and particularly to that type of pumping apparatus having a reciprocating hydraulic motor driven by supplying clean power oil under pressure from the surface, the motor being connected to drive the reciprocating pump therebelow. Devices of this general type are shown in the prior Sargent Patents Nos. 2,748,712; 2,787,223; 2,821,141 and 2,933,071.

This invention is directed to improvements over the disclosures of the above-listed patents. One of the features of invention of the present application resides in the provision of a reciprocating hydraulic motor and pump assembly in which the motor comprises a stationary barrel having a plunger which reciprocates within it, and wherein power oil under pressure is constantly supplied to the annular space below the plunger and between the barrel and the plunger rod, and wherein valve means within the plunger alternately pressurizes a circular space above vents it to exhaust through an internal passage in the plunger rod. Another feature of invention resides in a novel form of Valve mechanism within the plunger, which comprises a coaxial pilot valve and main valve positioned centrally on the plunger axis. Another feature of invention resides in the provision of a constant pump and engine ratio which is achieved by relating the effective areas of the motor plunger expo-sed to power oil in a manner so that the effective area of the motor plunger on the upstroke as compared to its effective area on the downstroke is the same ratio as the effective area of the pump piston on the upstroke to its effective area on the downstroke. By relating the effective motor and pump areas in this manner, there is provided a power ratio which remains constant for both upstroke operation of the combined assembly.

In the drawings:

FIGURE 1a is a sectional elevation in diagrammatic form showing a perferred embodiment of my invention. The positions of the internal parts correspond to upstroke of the plunger.

FIGURE 1b comprises an extension of the lower end of FIGURE 1a.

FIGURE 2a is a view similar to FIGURE 1a, the positions of the internal parts corresponding to downstroke of the plunger.

FIGURE 2b comprises a continuation of the lower end of FIGURE 2a.

FIGURE 3 is a view showing a portion of FIGURE 1a with the internal parts in position corresponding to upstroke reversal.

FIGURE 4 is a view similar to a portion of FIGURE la with the internal parts in position corresponding to downstroke reversal.

FIGURE 5 shows a modification.

FIGURE 6 shows the two-part pilot valve assembly.

FIGURE 7 shows the two-part main valve assembly.

Referring to the drawings, the hydraulic pump and motor device generally designated 10 is positioned within a first well tubing 11 and rests on a shoe 12 at the bottom of the tubing 11. The device 10 includes a reciprocating hydraulic motor generally designated 13 and a reciprocating hydraulic pump generally designated 14. In the form of the invention shown in the drawings, the motor 13 includes a reciprocating plunger 15 traveling within a stationary barrel 16, and the pump 14 includes a reciprocating piston 18 traveling within a stationary cylinder 19. The plunger rod 20 of the hydraulic motor 13 is fixed to or formed integrally with the piston rod 20a of the hydraulie pump 14. Accordingly, reciprocation of the motor plunger 15 within its barrel 16 under applied hydraulic forces, as described below, serves to reciprocate the pump piston 18 within its cylinder 19. Clean oil under pressure is supplied from the surface and passes down through the tubing 11, and the pressure of this power oil is applied at all times against the lower face 21 of the plunger 15. The plunger 15 is caused to reciprocate by alternately applying the pressure of the power oil to the upper end 22 of the plunger and then venting the space 23 to exhaust. Since the effective area of the lower face 21 of the plunger 15 is less than the effective area of the upper end 22 of the plunger 15, the plunger moves downward when power oil under the same unit pressure is applied to both ends of the plunger.

Valve means are provided for alternately pressurizing the space 23, and then connecting it to exhaust, and as shown in the drawings, this means includes connecting passages 25, 26, check valve chamber 27, and passage 28 in the upward projecting stem 29 on the upper end of the barrel 16. The pressure of the power oil is thus transmitted to the annular space 30 between the barrel 16 and the tubing 11, and then enters the interior of the barrel 16 below the plunger 15 through ports 31 and into space 32. The lower face 21 of the plunger defines the upper end of the space 32 and its lower end is dened by the seal rings 34 which slidably eng-age the outer surface 35 of the plunger rod 20. The seal rings 34 are carried in a ange 36 fixed to the lower end of the barrel 16.

The pressure of the power oil in space 32 below the plunger 15 of the hydraulic motor 13 passes through a pilot valve assembly generally designated 37 and a coaxial main valve assembly generally designated 38, both contained within the plunger 15. Power oil from space 32 constantly pressurizes the longitudinal passage 39 in the plunger 15. This passage 39 communicates with lateral passages 40, 41 and 42. In the position of the valve parts shown in FIGURE la, corresponding to the upstroke of the device, the inner end of the passage 42 is blocked by the `pilot valve 37 `while the passages 40 and 41 are both open to the internal chamber 43. The pressure of the power oil within this chamber 43 acts to hold the pilot valve assembly 37 in its upper (closed) position. It also acts to hold the main valve assembly 38 in its downward (closed) position. With the parts of both valve assemblies in closed position, the pressure of the power oil does not reach the space 23 above the plunger 15, and instead this Space 23 is vented to exhaust through longitudinal passage 45, transverse passage 46, internal cavity 47, passage 48, longitudinal passage 49, transverse passage 50, longitudinal bore 51 in the plunger rod 20, lateral port 52 therein, to the annular space 53 between the pump piston 21 and the -pump cylinder 54. The space 53 is connected to the second well tubing 55 through lateral passage 56 and 3 aligned port 57 in the wall of the cylinder 54 below the location of the seal rings 34. The pressure of the exhaust power oil in the passage 58 in the well tubing 55 is subp stantially less than the pressure of the power oil applied through well tubing 11, and accordingly the plunger moves upward within the barrel 16, pulling the pump piston 18 with it.

As the plunger 15 approaches the upper end of the barrel 16, the projecting plug 60 on the upper end of the plunger enters the dash pot cavity 61 in the stem 28, thereby slowing down the rate of upward movement of the plunger 15. Upward movement of the plunger continues at the lower rate of travel while the upper end 62 of the shifter 63 contacts the end wall 64 of the cavity 61, thereby shifting internal valve parts. The internal valve parts are then in the position shown in FIGURE 3, corresponding to upstroke reversal.

As shown in FIGURE 3, the upper shifter `63 moves the pilot valve assembly 37 downward with respect to the plunger 15, thereby moving the lower shifter 67 downward, so that its projecting end 68 extends below the lower face 21 of the plunger. Power oil under pressure is then admitted from passage 39 through passage 42 into annulus 69 and into longitudinal passage 70 through transverse passage 71. This power oil under pressure then reaches chamber 72 from transverse passage 73 and longitudinal passage 70. At the same time power oil under pressure passes from annulus 69 through transverse passage 75, longitudinal passage 76 and transverse passage 77 into recess 78. Hydraulic pressure in the recess 78 therefore holds the pilot valve assembly 37 in its mechanicallyshifted position.

Hydraulic pressure of the power oil in chamber 72 then shifts the main valve assembly 38 from the closed position shown in FIGURE 3 to the open position shown in FIG- URE 2a. In this position of the valve parts, the space 23 above the plunger 15 receives power oil under pressure from passages 45 and 46, annulus 47, passage 40 and longitudinal passage 39. As pointed out above, longitudinal passage 39 is constantly pressurized with power oil from space 32 below the plunger 15. As power oil is admitted under pressure into the space 23 above the plunger 15, it causes the plunger 15 to move downward because the effective area exposed to power oil pressure is greater above the plunger 15 than below it. This is true because the effective area of the plunger exposed to pressure in the chamber 23 is the full cross-sectional circular area of the bore of the barrel 16, while the effective area at the lower end of the plunger 15 is diminished by the cross-sectional area of the plunger rod which slides in the seal rings 34.

The valve parts remain in the position shown in FIG- URE 2 during the downstroke of the device, and when the plunger 15 approaches the lower end of this downstroke, the enlarged portion 80 of the plunger rod 20 enters the annular recess 81 to slow down the rate of travel of the plunger rod and plunger by dash-pot action. The collar 82 which slides on the cylindrical portion 83 of the plunger rod 20 then engages the stationary shoulder 84 and causes the collar 82 to contact the extending end 68 of the lower shift 67, and to move the pilot valve 37 to the position shown in FIGURE 4. In this position of the internal valve parts, the pressure of the power oil in the internal chamber 43 acting on the main valve assembly 38 causes it to move downward against the exhaust pressure in chamber 72, and back to the position shown in FIGURE 1a. This downward movement of the main valve assembly 38 is retarded as oil in the chamber 72 exhausts through restricted opening 85 in the main valve part 38a. The retarded rate of downward movement of the main valve part 38b insures gradual opening of the exhaust passage 48 to the passages 46 and 45 by way of annulus 47. The upper space 23 is thus vented to exhaust, and therefore the plunger 15 moves upward. This completes the cycle of the parts of the hydraulic motor 10.

The two parts 37a and 37b of the pilot valve assembly 37 function as a single integral unit, but are constructed as separate pieces in order that slight misalignment between the bores 86 and 87 can be tolerated without interfering with free axial movement of the parts 37b and 37a, respectively. Similarly, the two parts 38a and 38b of the main valve assembly 38 function as a single integral unit, but are constructed as separate pieces in order that slight misalignment between the bores 88 and 89 can be tolerated without interfering with free axial movement of the valve parts 38b and 38a, respectively.

The hydraulic pump generally designated 14 has a lower circular chamber 91 below the piston 18 and within the cylinder 19, and has an upper annular chamber 92 above the piston 18 and between the cylinder 19 and the piston rod 21. When the piston 18 is on the upstroke, as shown in FIGURE 1b, production fluid from the well enters the opening 93 in the seat 12, passes the valve 94 and through the space 95 and axial bore 96, space 97, past check valve 98, space 99, annulus 100, passageway 101, and into the expanding lower chamber 91. At the same time, production uid passes from the upper annulus chamber 92 through annulus 103, passage 104 and past check valve 105, and into annulus space 106 between the hydraulic pump 14 and the lower end of the well tubing 11. This well production fluid then passes downward through the annular space 106 to the region of the shoe 12 and out through passage 107 and into the interior 108 of the third well tubing 109. This third well tubing extends to the upper end of the well. During the upstroke of the pump piston 18, the valves and 111 remain closed because of the pressure of the hydraulic head of well Iiuid within the third tubing 109, as compared to the relatively lower formation pressure of the fluid passing the check valve 94.

During the downstroke of the pump piston 18, as shown in FIGURE 2b, well iiuid passes from the chamber 91 through passage 101, annulus 100, and space 99. The pressure closes the valve 98 and opens valve 110, so that well Huid under pressure passes from space 99 upward through opening 113, past check valve 110 and through axial bore 114 and radial passage 115 into the annular space 106, and then out through passage 107 and into tubing 109. At the sme time, the expanding annular chamber 92 receives well production iluid that passes check valve 94, space 95, and flows through passage 96, space 97, annulus 116, passage 117, and annulus 118, past check valve 111, and through annulus 103 to the chamber 92. During this downstroke of the pump piston 18, the valves 98 and 105 remain closed because the pressure of the hydraulic head of the well fluid in the tubing 109 is greater than the formation pressure of the well iluid entering the pump 14 past the check valve 94.

In accordance with this invention, and in order to produce maximum pumping eiciency throughout the cycle of upstroke and downstroke, certain ratios of effective areas are employed. This relationship may be expressed as follows:

where A is the effective area of the motor plunger exposed to power oil on the upstroke, B is the effective area of the motor plunger exposed to power oil on the downstroke, C is the effective circular area of the pump cylinder below the pump piston, and D is the effective annular area of the pump cylinder above the pump piston. This proportionate sizing of motor and pump areas provides for a given power ratio which remains constant for both upstroke and downstroke operation of the cornbined assembly. Stated in other terms, for each unit of effective area of the motor plunger exposed to power oil pressure, there is a corresponding unit area of the pump piston acting to pump well production iluid from the well, and this ratio does not change during the upstroke and downstroke.

In the modified form of hydraulic pump 14m shown in FIGURE 5, no third tubing 109l is employed, and instead, the well production fluid is mixed with the exhaust power oil and passes upward to the surface through the second tubing 55. The pump cylinder 19a has a check valve 98a at its lower end, and the pump piston 14a has a traveling valve 110a mounted at its lower end. A central bore 120` in the pump piston 14a communicates by axial passage 121 in the pump piston rod 21a with the axial passage 51 in the plunger rod 20, and with the lateral port 52a.

On the `downstroke of the pump piston 14a, the valve 98a is closed and the traveling valve 110a is open. Well fluid in the lower chamber 91a passes the valve l10n into the bore 120 and through passage 121 which communicates with the axial passage 51 in the plunger rod 20. The well fluid passes outward through port 52a, into annulus 53a, and passes through passage 57a. The well fluid then passes through passage 56 and into the second tubing 55. Check valve 111a remains open to admit well fluid into the upper pump chamber 92a via annulus 103:1.

On the upstroke of the piston rod 14a, well production iiuid is drawn from the formation past the check valve 94, through the space 95, bore 9'6, and into space 97, and this well production fluid passes check valve 98a and enters the lower pump chamber 91a. At the same time, traveling valve 110a is closed by the pressure of the hydraulic head of the mixture of exhaust power oil and production fluid in the tubing 55. Well production fiuid in the upper annular chamber 92a passes through annular space 103:1, passage 104@ past check valve 105a and into the second tubing 55 through annulus 106a and passage 56. The seal ring 125 (FIGURE 2a) and its adjacent shoulders are omitted in this form of the device so that the annulus 106a communicates directly with the passage 56.

The same pump and engine ratio is adopted, as set forth above, wherein the full circular area of the lower chamber 91a bears the same relationship to the annular area of the upper chamber 92a as the ratio of the effective annular area of the motor chamber 32 bears to the effective circular area of the motor chamber 23. As before, the operating pressure of the power oil required to reciprocate the pump piston is the same in both directions.

The device including the hydraulic motor assembly 13 and hydraulic pump 14 or 14a may be lowered as a unit into the tubing 16. A releasable tool (not shown) grasps the stem 29 at the upper end o-f the assembly, so that the asernbly may be lowered on a wire line until the lower end of the pump assembly 14 engages the shoe 12. The tool is then released and withdrawn on the wire line. A portion of the well tubing 16 on opposite sides of the lateral passage 56 is provided with a reduced bore 123 for sliding reception of axially spaced seal rings 124 and 125 carried on the member 36 which joins the motor barrel 16 to the pump cylinder 19. When the asasembly 10 is lowered into position, the seal rings 124 and 125 slidably engage the internal stationary surface 123. The assembly may be removed from the tubing 11 by lowering the releasable tool (not shown) on a wire line, engaging it with the stem 29 and then lifting the entire assembly 10 through the tubing 11.

Having fully described my invention, it is to be understood that =I am not to be limited to the details herein set forth, but that my invention is of the full scope of the appended claims.

1. In a reciprocating hydraulic motor and pump assembly for a well, the combination of a hydraulic motor having a stationary barrel and a plunger mounted to reciprocate in the barrel, a hydraulic pump below the motor having a stationary cylinder and a piston mounted to a reciprocate in the cylinder, stationary means connecting the motor barrel and the pump cylinder, a rod member fixed to the motor plunger and fixed to the pump piston so that the plunger, rod member and piston move as a unit, means including valve means associated with the pump piston and cylinder for lifting production fluid from the well upon reciprocation of the piston, seal means carried by said stationary means slidably engaging said rod member to define an annular space below the plunger and within the barrel, the rod member having an internal passage communicating with space outside the rod member below the seal means, means whereby a circular space is formed within said motor barrel and above said plunger, means for constantly subjecting said annular space to power oil under pressure, and means including valve means within said plunger whereby said circular space may alternately be subjected to power oil under pressure and then exhausted through said passage in said rod member, said valve means including a main valve assembly having an axially movable part and a pilot valve assembly having an axially movable part, said parts being positioned centrally of the plunger and axially aligned.

2. The combination set forth in claim 1 in which the main valve assembly is positioned below the pilot valve assembly.

3. The combination set forth in claim 1 wherein the valve means within the motor plunger includes a main valve assembly and an axially aligned pilot valve assembly thereabove, a first shifter on the plunger for mechanically shifting an element of the pilot valve assembly in one direction, a second shifter on the plunger for mechanically shifting said element in the other direction.

4. In a reciprocating hydraulic motor and pump assembly for a well having first and second tubings therein, the combination of: a hydraulic motor having a stationary barrel and a plunger mounted to reciprocate in the barrel, a hydraulic pump below the motor having a stationary cylinder and a piston mounted to reciprocate in the cylinder, stationary means connecting the motor barrel and the pump cylinder, a rod member fixed to the motor plunger and fixed to the pump piston so that the plunger, rod member and piston move as a unit, means including valve means associated with the pump piston and cylinder for lifting production fluid from the well upon reciprocation of the pump piston, said means also forming a circular charnber below the piston within the cylinder and an annular chamber between the rod member and the cylinder above the piston, seal means carried by said stationary means slidably engaging said rod member to define an annular space below said plunger and within said barrel, the rod member having an internal passage communicating with space outside said rod member and below said seal means, means whereby a circular space is defined within said motor barrel above said plunger, means whereby power oil supplied through the first well tubing constantly pressurizes said annular space, and means including valve means within said plunger whereby said circular space may alternately be filled with power oil under pressure and then exhausted through said rod passage to the second tubing, said valve means including a main valve assembly having an axially movable part and a pilot valve assembly having an axially movable part, said parts being positioned centrally of the plunger and axially aligned.

5. In a reciprocating hydraulic motor and pump assembly for a well having three tubings therein, the combination of: a hydraulic motor having a stationary barrel and a plunger mounted to reciprocate in the barrel, a hydraulic pump =below the motor having a stationary cylinder and a piston mounted to reciprocate in the cylinder, stationary means connecting the motor barrel and the pump cylinder, a rod member fixed to the motor plunger and fixed to the pump piston so that the plunger rod member and piston move as a unit, the hydraulic motor and pump assembly being insertable as a unit through a first of said well tubings, means including valve means associated with the pump piston and cylinder for lifting production fluid from another of the well tubings upon reciprocation of the pump piston, said means also forming a circular charnber below the piston within the cylinder and an annular chamber between the rod member and the cylinder above the piston, seal means carried by said stationary means slidably engaging said rod member to define an annular space below said plunger and within said barrel, the rod member having an internal passage communicating with said space outside said rod member and below said seal means, means whereby a circular space is defined within said motor barrel above said plunger, means whereby power oil supplied through the first well tubing constantly pressurizes said annular space, and means including valve means within said plunger whereby said circular space may alternately be filled with power oil under pressure and then exhausted through said rod passage to another well tubing, said valve means including a main valve assembly having an axially movable part and a pilot valve assembly having an axially movable part, said parts being positioned centrally of the plunger and axially aligned.

6. In a reciprocating hydraulic motor and pump assembly for a well, the combination of a hydraulic motor having a stationary barrel and a plunger mounted to reciprocate in the barrel, a hydraulic pump below the motor having a stationary cylinder and a piston mounted to reciprocate in the cylinder, stationary means connecting the motor barrel and the pump cylinder, a motor rod -xed to the motor plunger, a pump rod fixed to the pump piston, said rods being joined for axial movement as a unit, means including valve means associated with the pump piston and cylinder for lifting production fluid from the well upon reciprocation of the piston, said valve means including an inlet valve and a discharge valve at the lower end of the pump and an inlet valve and a discharge valve above the piston and adjacent the pump rod, seal means carried by said stationary means slidably engaging said motor rod to define an annular space below the plunger and within the barrel, seal means carried by said stationary means slidably engaging said pump rod to define an annular chamber `between said seal means, the motor rod having an internal passage communicating with said chamber, means whereby a circular space is formed within said motor barrel and above said plunger, means for constantly subjecting said annular space to power oil under pressure, and means including valve means within the plunger whereby said circular space may alternately be subjected to power oil under pressure and then exhausted through said passage in said motor rod, the pump cylinder having a circular chamber therein below the piston and an annular chamber therein above the piston and around the pump rod, the effective area of the motor plunger exposed to power oil on the upstroke having substantially the same relation to the effective area of the motor plunger exposed to power oil on the downstroke as the effective circular area of the pump cylinder below the pump piston bears to the effective annular area of the pump cylinder above the pump piston.

7. The combination set forth in claim 6 wherein the valve means within the motor plunger includes a main valve assembly having an axially movable part and a pilot valve assembly having an axially movable part, said parts being positioned centrally of the plunger and axially aligned.

8. The combination set forth in claim 6 in which the main valve assembly is positioned below the pilot valve assembly.

9. The combination set forth in claim 6 wherein the valve means within the motor plunger includes a main valve assembly and an axially aligned pilot valve assembly thereabove, a first shifter on the plunger for mechanically shifting an element of the pilot valve assembly in one direction, and a second shifter on the plunger for mechanically shifting said element in the other direction.

References Cited UNITED STATES PATENTS 2,682,257 6/ 1954 Deitrickson 91-321 XR 2,834,294 571958 Schoen 103-46 2,921,531 1/1960 Brennan et al 103-46 ROBERT M. WALKER, Primary Examiner U.S. Cl. X.R.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2682257 *Jul 7, 1952Jun 29, 1954Nat Supply CoFluid operated engine for downwell pumps
US2834294 *Aug 13, 1953May 13, 1958Alco Valve CoDeep well pump
US2921531 *Mar 13, 1958Jan 19, 1960Nat Supply CoPressure fluid-operated pump structure
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3703926 *Dec 3, 1970Nov 28, 1972George K RoederDownhole hydraulic pump and engine improvements
US4118154 *May 24, 1976Oct 3, 1978Roeder George KHydraulically actuated pump assembly
US4214854 *Sep 11, 1978Jul 29, 1980Roeder George KHydraulically actuated pump assembly having mechanically actuated valve means
US4925374 *Jan 9, 1989May 15, 1990Carrens Donald EDown hole hydraulically actuated pump
US6886226 *Sep 27, 2000May 3, 2005Textron Fastening Systems LimitedRiveting apparatus
US6948917Mar 10, 2003Sep 27, 2005Donald CarrensValving system for a downhole hydraulically actuated pump
US20040131488 *Dec 2, 2003Jul 8, 2004Locher Ben C.Water well pump
Classifications
U.S. Classification417/404, 91/321
International ClassificationF04B47/04
Cooperative ClassificationF04B47/04
European ClassificationF04B47/04
Legal Events
DateCodeEventDescription
Jun 19, 1992ASAssignment
Owner name: EVI-HIGHLAND PUMP COMPANY
Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:TRANSAMERICA BUSINESS CREDIT CORPORATION;REEL/FRAME:006164/0594
Effective date: 19920324
Jun 19, 1992AS17Release by secured party
Owner name: EVI-HIGHLAND PUMP COMPANY
Effective date: 19920324
Owner name: TRANSAMERICA BUSINESS CREDIT CORPORATION
Jul 23, 1991ASAssignment
Owner name: CITICORP NORTH AMERICA, INC., NEW YORK
Free format text: SECURITY INTEREST;ASSIGNOR:EVI-HIGHLAND PUMP COMPANY;REEL/FRAME:005775/0330
Effective date: 19910329
Jul 23, 1991AS06Security interest
Owner name: CITICORP NORTH AMERICA, INC. A CORPORATION OF DE 4
Owner name: EVI-HIGHLAND PUMP COMPANY
Effective date: 19910329
Feb 20, 1990ASAssignment
Owner name: EVI-HIGHLAND PUMP COMPANY, TEXAS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:LUFKIN INDUSTRIES, INC.;REEL/FRAME:005249/0226
Effective date: 19891222
Feb 20, 1990AS02Assignment of assignor's interest
Owner name: EVI-HIGHLAND PUMP COMPANY, A CORP. OF TX
Owner name: LUFKIN INDUSTRIES, INC.
Effective date: 19891222
Dec 31, 1985AS02Assignment of assignor's interest
Owner name: DELAWARE CAPITAL FORMATION, INC., 1100 NORTH MARKE
Effective date: 19851231
Owner name: SARGENT INDUSTRIES, INC.
Dec 31, 1985ASAssignment
Owner name: DELAWARE CAPITAL FORMATION, INC., 1100 NORTH MARKE
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:SARGENT INDUSTRIES, INC.;REEL/FRAME:004500/0355
Effective date: 19851231