US3554093A - Constant power regulator for hydraulic pumps - Google Patents

Constant power regulator for hydraulic pumps Download PDF

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Publication number
US3554093A
US3554093A US779881A US3554093DA US3554093A US 3554093 A US3554093 A US 3554093A US 779881 A US779881 A US 779881A US 3554093D A US3554093D A US 3554093DA US 3554093 A US3554093 A US 3554093A
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Prior art keywords
pump
pressure
adjusting mechanism
slide element
responsive
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US779881A
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Kurt R Lonnemo
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Vickers Inc
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Sperry Rand Corp
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Assigned to VICKERS, INCORPORATED reassignment VICKERS, INCORPORATED ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: SPERRY CORPORATION A DE CORP.
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/08—Regulating by delivery pressure

Definitions

  • the continuous variamechanism which is actuated by the action of the pump outlet pressure on'a movable contact surface and, in the opposite direction, by a spring unit, and which controls a selective pressure liquid supply to the actuating device in such a way that, when the pump outlet pressure rises above the value determined by the choice of spring unit, the device automatically actuates the adjusting mechanism in such a way that the displacement of the pump is diminished, and vice versa.
  • This type of regulator is usually called a pressure-compensating device and also exists in certain variants, in which the valve mechanism is acted upon in the second direction, not only'by the spring unit, but also, either direc'tly'by the hydraulic pressure which operates the actuating device, or by a secondary piston which, in turn, is acted upon by the pressure of said device or by the pump outlet pressure;
  • the regulator assures that the efflux from the pump is adjusted immediately thereafter, doing so in such a manner that the power delivered by the pump or, if this is desirable, the power delivered to the pump by the drive motor,'isalways constant.
  • the purpose of the present invention is to create a constant power regulator, in which the aforesaid disadvantages are eliminated entirely and by means of which an adjustable pressure-flow characteristic, regular and undisturbed over the whole range of regulation, is obtainable while using very sim-' ple and inexpensive means.
  • the invention can be considered to be a further development and amplification of the previously mentioned pressure compensating devices, inasmuch as it, similar to them, is based on both a hydraulically operated device for actuating the pump adjusting mechanism, and also a valve mechanism which, in one direction, is acted upon by the action of the pump outlet pressure on one of the movable contact surfaces and, in the opposite direction, by a spring unit, as well as a cooperating hydraulic pressure which acts on the other contact surface.
  • the first contact surface is disposed on the valve mechanism itself while the second may also likewise be disposed, but generally, instead, is fashioned as a so-called return" piston, separate from the valve mechanism. but acting upon it.
  • the characterizing feature of the constant power regulator according to the invention is that the pressure which works in unison with the spring unit is regulated by a pressure-varying device, as a function of the position of the pump-adjusting mechanism.
  • the pressure which works in unison with the spring unit is thus varied in such a way that it increases, or decreases, in proportion to the pump outlet pressure and in step" with it, and inversely proportional to the increase, or decrease, in the pump displacement.
  • the force of the spring unit acting on the valve mechanism which (force) expediently can be adjusted, in a manner in itself know, by presetting, determines, in the regulator according to the invention, not only the lowest pressure on the discharge side of the pump, at which the regulator is to commence operating, but also the power of the pump to be held constant, which brings about a far-reaching simplification of the adjustment of the power level. Because of the continuous interaction, during operation of the regulator between the pump outlet pressure and the controlled-pressure which works in unison with the spring unit, maximum uniformity in the pressure-flow characteristic is thus obtained, independent of the set magnitude of the power, and the need for complicated spring and limiting devices in the regulator, disappears completely.
  • the pressure-varying device incorporated in the constant power regulator according to the invention preferably comprises at least one variable constriction and has its simplest and most appropriate form when the variable constriction is fashioned as a leakage slit of variable length between a slide member and an interacting sleeve which are so disposed as to proportionately change their relative positions, when the pump-adjusting mechanism moves.
  • the maximum length of the leakage slit (s) that is the maximum attainable choke effect can thus easily be adjusted in a very advantageous manner, to include the desired adjustment of the pressureflow characteristic, depending on for example pump leakage or other factors.
  • the characteristic can also be changed by a suitable choice of the relative magnitude of the two contact surfaces, by means of which the valve mechanism is operated by the regulated pressure which works in unison with the spring unit and the pump outlet pressure, respectively.
  • the slide element with one active part of limited length dimensions in the direction of motion of the slide member relative to the sleeve, said active part communicating on one side with the pump inlet and, on the other side, with the pump outlet, and to design the part of the sleeve which functions with the active part of the slide element with a discharge opening for the regulated pressure which operates in unison with the spring unit, past which discharge opening the active part of the slide element is arranged to move in such a manner that, at least in some operating positions, a two-sided leakage slot is obtained, with relation to the discharge opening.
  • the entire length of the leakage slot may be available between the discharge opening and the discharge side of the pump, but when the active part of the slide element later is displaced, due to a change in position of the pump-adjusting mechanism, that is due to displacement of the pump, the length of the leakage slot and the associated choke effect are distributed on both sides of the discharge opening.
  • the slide element is fashioned as a body which can move axially in a cylindrical bore in the sleeve, and if the regulator actuating device has the form of a piston, in which case the slide element is conveniently disposed coaxially with said piston and in such a way that. by means of mechanical contact, the former follows the movements of the latter. Consequently, the construction of the regulator can be made extremely compact and can easily be incorporated in the pump housing itself, either completely or in part.
  • FIG. 1 shows, partly schematically and in section, one embodiment of the constant power regulator according to the invention, in which the pressure-varying device comprises a rectilinearly movable slide element.
  • FIG. 2 likewise partly schematic and in section, shows a second embodiment of the constant power regulator, in which the pressure-varying device includes a rotary slide element.
  • FIG. 3 shows, in turn, partly schematic and in section, a variant of the constant power regulator according to FIG. 1, assembled with an axial piston pump of a well-known type, readily available on the open market.
  • FIG. 4 finally, shows, in the form of a curve diagram, a representative example of the pressure-flow characteristic of a constant power regulator according to the invention, with some different settings and modifications of details.
  • FIG. 1 indicates a hydraulic pump with continuously variable displacement, shown only schematically, inasmuch as it may be of a type known in itself.
  • the pump 1 has a discharge line 2, an inlet line 3 and in addition is provided with an adjusting mechanism 4, which in the drawing is conceived to be vertically movable and which, in a manner in itself known, acts on the pump so that the displacement of the latter, and with it also the efflux, is decreased at a constant rotary speed, when the adjusting mechanism 4 is pushed downward, and vice versa.
  • the regulator itself which in general is designated by 5, is connected by a line 6 to the discharge side of the pump 1 and to the inlet side of the pump by means of a line 7. In actual practice the regulator and pump are often joined together in such a way that the lines 6 and 7 can be replaced by short channels.
  • the regulator itself comprises a housing or sleeve 8, in which is disposed a borehole 9, in which a slide 10, serving as a valve mechanism, is axially movable.
  • the line 6 connects with the lower end of borehole 9, and from this emanates another channel 11, the purpose of which is to be described later.
  • borehole 9 is crossed by another bore 12, which. via a channel [3, communicates with a third borehole 14 in the regulator housing and also via a branch line 13'.
  • borehole 9 communicates again, via channel 15, with borehole l4 and, in addition, with the discharge side of a pressure-limiting valve 16, incorporated in the regulator housing.
  • borehole 9 opens into a larger bore 17, the upper end of which is sealed by a threaded plug 18, which can be screwed in or out and thus serves as an adjusting device.
  • the slide 10 is provided with an annular flange 10' which has an insignificantly larger axial thickness than borehole 12 and the upper end of the slide is, in addition, equipped with a cap 10" which is guided in the upper end section of borehole 9, without completely blocking it.
  • the cap 10 makes contact in the larger bore 17 with a connecting piece 19 which is subject to the action of a spring 20, the upper end of which rests against the plug 18 and which tries to force the connecting piece 19, and with it also the slide 10, in a downward direction.
  • the connecting piece I9 is acted upon. at its upper end, by a secondary piston 21 which moves axially in a borehole 22 in the lower end of plug 18.
  • the plug 18 has double, axially separated, seals 23 and 24, against the surrounding parts of the regulator housing 8. and the upper part of bore 22 communicates, via the interspace between these seals, and via a channel 25, both with the inlet side of the pressure-limiting valve 16 and with an annular recess 26 in bore 14.
  • a lengthy slide element In the borehole 14 is disposed a lengthy slide element, generally designated by 27.
  • This slide element has the form of a relatively thin rod, the lower part of which forms a shaft 28, and the upper part of which is provided with three, axially separated, cylindrical enlargements 29, 30 and 31, respectively, of which the lowest 29 and the uppermost 31 have a suffciently large diameter to act as a seal, at least substantially, with the wall of borehole 14, as the slide element moves along axially, while the middle enlargement 30 expediently has asomewhat smaller diameter so that between the same and the wall of borehole 14 an annular leakage gap 32 is formed.
  • slide element 27 works in unison with a spring 33 which seeks, with a moderate force, to push the slide element downward in the HQ, and the shaft 28 of the slide element rest 5, with its lower end, against an adjusting piston 34, which can move axially in a cylindrical chamber 36, against the action of a more powerful spring 35, said chamber forming a widened axial extension of borehole 14,
  • the piston 34 via shaft 34', communicates directly with the pump-adjusting mechanism 4, in such a manner that the adjusting piston completely controls the location of the adjusting mechanism.
  • channel 11 which also communicates openly with the discharge side of the pump, opens between the two upper enlargements 31 and 32 of the slide element, while channel 13 opens beneath the lower slide element enlargement 29 and consequently communicates openly, via borehole 14, with the cylindrical chamber 36 above the adjusting piston 34, while at the same time communicating, via branch 13', with the upper end of borehole 14, above the upper enlargement of the slide element 31.
  • channel 15 opens into the borehole 14 at a level between the lowest and middle slide element enlargement 29 and 30, respectively, and this part of borehole 14 is also connected to the inlet side of the pump, via line 7.
  • the slide element 27 is also, at least approximately, balanced from the hydraulic point of view.
  • the slide 10 in borehole 9 in itself acts as a contact surface for the pump outlet pressure, which seeks to push the slide upward against the action of spring 20, inasmuch as the upper part of bore 9, as well as the larger borehole l7, are subject to the low inlet pressure of the pump.
  • the annular flange 10 on slide 10 serves, in conjunction with the transverse bore 12, as a selective valve device, which, on increase of the pump outlet pressure in lines 2 and 6, beyond a certain value primarily determined by spring 20, brings in pressure fluid into channel 13 and at the same time produces a motion of the adjusting piston 34 in a downward direction.
  • the slide 10 instead, moves downward and pulls out pressure fluid from the channel 13, via channel 15 and line 7 to the pump inlet side, so that the adjusting piston, acted upon by spring 35, moves upward.
  • This operation is in itself well known from so-called pressure-compensating devices. Since, however, the slide element 27 follows the motion of the adjusting piston 34, the middle enlargement 30 of the slide element moves relative to the annular recess 26 in bore 14, so that the entire length of the leakage gap 32 is distributed on both sides thereof, and thus the fluid pressure in channel 25 is caused to vary proportionally with the motion of the adjusting piston 34.
  • the thus regulated pressure in channel 25 acts on the secondary piston 21 which then seeks, by way of connecting piece 19, to force the slide downward-against the action of the pump outlet pressure. It should be noted that the secondary piston 21 acts parallel with, and not via, the' spring 20.
  • the maximum pressure for each power level is limited, which is accomplished by means of the fixed adjustment of the pressure-limiting valve 16, which provides a limitation of the pressure in the system, without loss of power, because it operates between the regulated pressure in channel 25 and the pump inlet side.
  • the pressure-limiting valve 16 could be adjustable, and it might also be replaced by an ordinary overflow valve, situated in a suitable manner between the outlet and inlet sides of the pump.
  • curves B and B" respectively (broken line and dot-dash) it is possible, by making certain variations in the regulator, to adjust the pressureflow characteristic according to the pump leakage and other factors. Naturally, in such a case, these adjustments occur at all power levels, although these will not be shown, for the sake of clarity.
  • Curve 8' can be obtained either by increasing the area of the secondary piston 21 in relation to the'contact area on slide 10, acted upon by the pump outlet pressure, and/or by shortening the length of the middle enlargement (which forms the leakage gap) on slide element 27, so that it becomes shorter than the stroke of adjusting piston 34.
  • Curve B" is obtained by decreasing the area of the secondary piston, in relation to the contact area on slide 10 and/or by making the enlargement'30 longer than the stroke of the adjusting piston.
  • the constant power regulator shown in FIG. 2 does not differ substantially, from a functional point of view, from the one shown in FIG. 1, but has partly assumed another structural design, due to the fact that the pump 1 is assumed to be of such a type that its adjusting mechanism 4 can expediently be fashioned as a rotary shaft which acts on the adjusting piston 34 of the regulator, via a rack 38 and pinion 37. Then the shaft 4' continues beyond the pinion 37 and is directly connected with a rotary slide 39 which operates in a separate sleeve 40, which (because of technical aspects of drawing) is shown apart from the actual regulator housing 8, although in actual practice it can certainly be incorporated therein.
  • the details included in the regulator housing B can correspond in all respects to those shown in FIG.
  • the channels l1, l5 and 25 lead to the sleeve 40 and they open into a cylindrical chamber 41, disposed therein, for the rotary slide 39.
  • the rotary slide is provided with two axially extending recesses 42 and 43, respectively, between which is located a protrusion 44 which expediently may have a somewhat smaller radius than the remainder of the rotary slide, thus forming a leakage gap 45 between the recesses 42 and 43 and the outlet of channel 25. Otherwise, the rotary slide 39 satisfactorily seals against the sleeve 40, and is not substantially affected by any torque produced by the pressure exerted on the working chamber 41.
  • the pressure on the secondary piston comes down again and the overall effect is that the desired pressureflow characteristic obtained is in accordance with the curves shown in FIG. 4.
  • the pretension on spring 20 is the factor which determines the power level and the lowest pressure at which the regulating function begins.
  • the pressure-limiting valve 16 limits the maximum pressure in the same manner as before.
  • the length of the leakage gap is of course determined by the peripheral width of the protrusion 44, between recesses 42 and 43, that is by the angle a and this is therefore what is changed, when required, to adjust the characteristic of the regulator in relation to the leakage of a given pump and other factors affecting power.
  • this adjustment can also be made alternatively by changing the area of the secondary piston 21 in relation to the slide 10, which may be more convenient, inasmuch as the plug 18 and the corresponding piston are easily interchangeable.
  • a variant of a constant power regulator is shown, which is particularly suitable for use with, and assembled as a unit with, an axial piston pump with continuously variable displacement, of the usual type available on the market.
  • the pump itself is shown in detail, in schematized form.
  • the principal components thereof comprise a pump housing 50 with a pump housing cover 51.
  • a drive shaft 52 is mounted in the pump housing and cover and supports a rotor 53 which houses an annular series of pump cylinders 54 each of which incorporates an axially movable pump piston 55.
  • Each pump cylinder 54 has an opening 56 at its upper end and these openings, as the rotor turns, function, in a manner like that of a slide valve, with the pump housing cover 51, in which are disposed curved bends with inlet and outlet channels, not shown in the drawing.
  • the pistons 55 in the different cylinders 54 work in unison with an obliquely set yoke 57 in such a manner that, as the rotor revolves, they produce an axial backand-forth motion.
  • the yoke 57 is pivoted in the pump housing 50 around pins represented by center 58 and is actuated on one side by a powerful spring 59 so as to assume the oblique position shown, when under no pressure.
  • the yoke 57 can swing clockwise against the action of spring 59, around its supporting pins at 58, so that the upper side of the yoke lies in a plane perpendicular to the drive shaft and the rotor 53. With such a position of the yoke, the axial motion of pistons 55, and thus the pump displacement, is reduced to zero. Thus. the pump displacement is continuously variable, and the yoke 57 represents, in fact, the pump-adjusting mechanism.
  • the entire pump housing 50 is filled with the oil which is to be pumped, and thus the pressure on this oil can represent the pump inlet pressure. Although this is not immediately evident, this pressure also prevails in the channel 60 shown in cover 51, while channel 61 in the cover is connected, in a mariner not shown, with the outlet side of the pump, and thus the pump outlet pressure prevails in it.
  • the channel 61 in the pump housing cover 51 is connected to a channel 6a, the upper end of which opens into a borehole 9a, enclosing a slide 10a, of the same type as in FIG. 1 and FIG. 2.
  • the top of slide 10a makes contact, inside a larger bore 17a, with a connecting piece 19a, which is acted upon by a spring 20a, which, in turn, bears against a plug 18a, adjustable by screwing in or out.
  • a return piston 21a Centrally in the plug is disposed a return piston 21a, in a borehole 22a.
  • the first-mentioned bore 9a communicates via a channel 150 with channel 60 in the pump housing cover 51, where, as was previously stated, a pressure comparable with the pump inlet pressure prevails.
  • the annular recess 12a which works in conjunction with the annular flange l0'a on slide 100, communicates with a channel 13a, which may be said to be extension of borehole 14a in the tubular sleeve 64 of the slide element.
  • a transverse hole 7a which puts the borehole 14a into open communication with the interior of the pump housing and thus guarantees the pump inlet pressure in part of the bore.
  • the slide element itself 27a in this case has the form of a tube, the interior of which forms a prolongation of channel 13a and allows pressure oil from the annular recess 12a to penetrate down to the lower end of the slide clement 27a and thus not only to balance the slide element but also to act on the adjusting piston 34, which in this case encloses the lower part of the sleeve 64 like a shell and is guided by it, exerting its action directly on the yoke 57.
  • the tubular slide element 27a is fashioned with three axially separated enlargements, namely a lower enlargement 29a, which provides a sliding seal in borehole 14a, a centrally located enlargement 30a and an upper enlargement 31a, which likewise forms a sliding seal in borehole 140.
  • an annular leakage gap 32 is disposed around the middle enlargement 30a, which expediently can have a somewhat smaller diameter than the other two, and enlargement 30a is here also designed so that, as the slide element moves vertically, it works in unison with an annular recess 26a in borehole 14a.
  • This annular recess 26a communicates, via a line 25a (indicated in broken lines) with the return piston 21a, on its left side.
  • the slide element 27a is acted upon by a spring 33a, downward as shown in the drawmg.
  • the constant power regulator shown in FIG. 3 is, in principle, constructed in the same way as the regulator according to FIG. I, and in operation is also equivalent.
  • the adjusting piston spring 35, shown in FIG. 1, is represented in FIG. 3 by the spring 59.
  • An increased outlet pressure in the pump seeks to push the slide 10a to the left, so that pressure fluid is fed to the adjusting piston 34a, whereon it seeks to decrease the slope of yoke 57 and, with it, the displacement of the pump.
  • the slide element 27a accompanies the movement of the adjusting piston and, due to the decreased length of the leakage gap about the annular recess 26a, lowers the pressure on secondary piston 210, so that a new equilibrium position is reached immediately, corresponding to the increased pressure.
  • a corresponding turn of the yoke 57 leads to decrease in the pump displacement and, with it, the efflux, so that the power input or output of the pump remains constant, according to the detailed dimensioning of the regulator, as was previously described.
  • a decrease in the pump outlet pressure involves an inverse operation, so that the pump efflux again increases.
  • pressure compensated means for varying the displacement of the pump including a pump-adjusting mechanism; means responsive to the outlet pressure of the pump for moving said pump-adjusting mechanism;
  • variable displacement pump including:
  • pressure compensated means for varying the displacement ofthe pump including a pump-adjusting mechanism; means responsive to the outlet pressure of the pump for moving said pump-adjusting mechanism;
  • pressure compensated means for varying the displacement of the pump including a pump-adjusting mechanism; means responsive to the outlet pressure of the pump for moving said pump-adjusting mechanism;
  • said secondary means comprises at least one variable constriction
  • variable constriction comprises:
  • a body a slide element
  • variable constriction comprising at least one leakage gap between said body and said slide element
  • said slide element being movable in response to movement of said pump-adjusting mechanism.
  • said pumpadjusting mechanism comprises a piston, said slide element being disposed coaxially with said piston and engaging said piston so that itmoves in conjunction with said piston.
  • pressure-compensated means for varying the displacement of the pump including a pump-adjusting mechanism
  • said pressure responsive means comprises a spool
  • said secondary means comprises a second spool associated with said first-mentioned spool
  • variable displacement pump including:
  • pressure-compensated means for varying the displacement (of the pump including a pumpadjusting mechanism
  • said secondary means comprises at least one variable constriction
  • variable constriction comprises:
  • a body a slide element
  • variable constriction comprising at least one leakage gap between said body andsaid slide element
  • said slide element being movable in response to movement of said pump-adjusting mechanism.
  • variable displacement pump including:
  • pressure-compensatedmeans for varying the displacement of the pump including a pump-adjusting mechanism; means responsive to the outlet pressure of the pump for moving said pump-adjusting mechanism;
  • said pressure responsive means comprises a spool
  • said secondary means comprises a second spool us- 5 sociated with said first-mentioned spool;
  • the combination comprising: a variable displacement pump; a pump-adjusting mechanism for varying the displacement of the pump; pressure-responsive means responsive to the outlet pressure of the pump for moving said pump-adjusting mechanism; spring means yieldingly opposing said pressure-responsive means; and secondary means responsive to theoutlet flow rate of the pump for applying a hydraulic pressure to said pressureresponsive means in conjunction with said spring means to modulate the pump-adjusting mechanism.
  • valve member having a first contact surface and a second contact surface
  • said first contact surface being hydraulically connected to the pump outlet pressure
  • valve member having hydraulic pressure applied thereto.
  • Constant power regulator for those hydraulic pumps, the displacement of which is continuously variable by action of a movable adjusting mechanism, said regulator comprising both a hydraulically operated actuating device which acts on said adjusting mechanism, and also a valve mechanism which is actuated in one direction by the action of the pump outlet pressure on one movable contact surface, and in the opposite 40 direction by a spring unit, as well as by a hydraulic pressure which works in conjunction therewith and acts on the other contact surface, and which provides for such a selective feed of pressure fluid to the actuating device that, when the pump outlet pressure rises above a value determined by the choice of spring unit, it acts on the adjusting mechanism automatically in such a way that the displacement of the pump is decreased, and vice versa, characterized in that the pressure which works jointly with the spring unit is regulated by a pressure-varying device, depending on the position of the pumpadjusting mechanism, said pressure varying device comprising at least two variable constrictions to a discharge opening which communicates with the spring unit, one of said constrictions communicating with said pump inlet and
  • Constant power regulator according to claim 18, 60 characterized in that the variable constrictions comprises at least two leakage gaps of variable length between a slide element and sleeve which works in unison with it, these being so disposed as to change their relative positions proportionally when the pump-adjusting mechanism is moved.
  • Constant power regulator according to claim 19, characterized in that the slide element has an active part of limited extent in the direction of motion of the slide element relative to the sleeve, said active part communicating on one side with the pump inlet and on the other side with the pump outlet, and that the part of the sleeve which works in unison with the active part of the slide element being provided with said discharge opening for the regulated pressure which works in conjunction with the spring unit,- past which discharge opening the active part of the slide element is disposed to 75 move, so that in at least certain operating positions a twopiston and so as to follow its inovements, due to mechanical contact.
US779881A 1967-12-04 1968-11-29 Constant power regulator for hydraulic pumps Expired - Lifetime US3554093A (en)

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SE16593/67A SE323286B (de) 1967-12-04 1967-12-04

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US779881A Expired - Lifetime US3554093A (en) 1967-12-04 1968-11-29 Constant power regulator for hydraulic pumps

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DE (1) DE1812682C3 (de)
GB (1) GB1242239A (de)
SE (1) SE323286B (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4175914A (en) * 1977-05-31 1979-11-27 The Cessna Aircraft Company Hydraulic stop
US4296678A (en) * 1979-02-12 1981-10-27 Felder Donald W Polish rod jack system
EP0226125A2 (de) * 1985-12-13 1987-06-24 Vickers Incorporated Pumpanordnung mit veränderlicher Verdrängung

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5517234B2 (de) * 1973-09-20 1980-05-09
US3945764A (en) * 1974-09-05 1976-03-23 Parker-Hannifin Corporation Variable displacement pump control assembly
US3941513A (en) * 1974-09-05 1976-03-02 Parker-Hannifin Corporation Variable displacement pump control assembly
US4157233A (en) * 1975-07-04 1979-06-05 Daikin Kogyo Co., Ltd. Variable delivery hydraulic pump
US4072442A (en) * 1975-07-04 1978-02-07 Takeshi Horiuchi Variable delivery hydraulic pump
FR2552187B1 (fr) * 1983-09-20 1987-08-28 Linde Ag Dispositif de commande ou de regulation pour une transmission hydraulique

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2283321A (en) * 1937-04-15 1942-05-19 Waterbury Tool Co Power transmission
US2903852A (en) * 1956-10-29 1959-09-15 Lucas Industries Ltd Control means for road vehicle hydraulic power transmission systems

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2283321A (en) * 1937-04-15 1942-05-19 Waterbury Tool Co Power transmission
US2903852A (en) * 1956-10-29 1959-09-15 Lucas Industries Ltd Control means for road vehicle hydraulic power transmission systems

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4175914A (en) * 1977-05-31 1979-11-27 The Cessna Aircraft Company Hydraulic stop
US4296678A (en) * 1979-02-12 1981-10-27 Felder Donald W Polish rod jack system
EP0226125A2 (de) * 1985-12-13 1987-06-24 Vickers Incorporated Pumpanordnung mit veränderlicher Verdrängung
EP0226125A3 (en) * 1985-12-13 1989-07-05 Vickers, Incorporated Variable displacement pump system variable displacement pump system

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SE323286B (de) 1970-04-27
DE1812682C3 (de) 1975-03-27
DE1812682B2 (de) 1974-08-01
GB1242239A (en) 1971-08-11
DE1812682A1 (de) 1969-07-03

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