US3686856A - Hydraulic servomotor with air motor - Google Patents

Hydraulic servomotor with air motor Download PDF

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US3686856A
US3686856A US90341A US3686856DA US3686856A US 3686856 A US3686856 A US 3686856A US 90341 A US90341 A US 90341A US 3686856D A US3686856D A US 3686856DA US 3686856 A US3686856 A US 3686856A
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servomotor
space
plunger
hollow
conduit means
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Witold Rozwadowski
Aleksander Szymanski
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GLOWNE B ST P ZEPLECZA TECHNIC
GLOWNE BIURO STUDIOWI PROJEKTOW ZEPLECZA TECHNICZNEGO WARSZAWA
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GLOWNE B ST P ZEPLECZA TECHNIC
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/028—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force
    • F15B11/032—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force by means of fluid-pressure converters
    • F15B11/0325—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force by means of fluid-pressure converters the fluid-pressure converter increasing the working force after an approach stroke
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/21—Systems with pressure sources other than pumps, e.g. with a pyrotechnical charge
    • F15B2211/216—Systems with pressure sources other than pumps, e.g. with a pyrotechnical charge the pressure sources being pneumatic-to-hydraulic converters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7053—Double-acting output members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/775—Combined control, e.g. control of speed and force for providing a high speed approach stroke with low force followed by a low speed working stroke with high force, e.g. for a hydraulic press

Definitions

  • the servomotor is constructed as an integral unit and consists of the piston air motor of one-sided action and of relatively high frequency running, hydraulic storing system under pressure: and appropriate servomotor. By means of these servomotors operating forces of the order of a few to a dozen or so tons could be obtained.
  • the present invention relates to an hydraulic servomotor with air motor, which drives an hydraulic piston pump delivering the liquid to operating chamber of a plunger cylinder.
  • this design makes it impossible to use hydraulic pistons of pumps of a diameter less than 12 to 15 mm; thus this design cannot be used in constructing small-size motors for higher pressures of the order from 300 to 600 kg/cm, in which the diameter of the hydraulic piston is of the order of 4- to 8 mm.
  • a further drawback of the design of the hydraulic servomotor with air motor being known at present consists in the fact that the servomotor can operate only in a vertical position, since the fluid level in the plunger is free, while for the regular operation of the servomomotor a constant and perpendicular position of the fluid with respect to the plunger is required.
  • the purpose of this invention is to eliminate the above mentioned drawbacks and to develop such a design of hydraulic servomotors with air motors, which will permit application of a wide range of diameters of hydraulic pistons, beginning with the values of the order 2 to 3 mm and will ensure at the same time an unchanged position of the fluid level with regard to the plunger.
  • the pneumatic conduit feeding the compressed air to the upper space of the hollow plunger has been made in the lateral wall surrounding the recess in which the piston of the hydraulic pump is moving.
  • the fluid has been separated from the compressed air by a baffle in a form of a tightly fitting piston sliding on the inner surface of the plunger and the outer surface of the pneumatic conduit.
  • the hydraulic servomotor with air motor being so designed will permit using it not only for lifting devices,
  • FlG. ll represents the longitudinal half-section of the hydraulic servomotor with air motor, while MG. 2 shows the cross-section through the outlet,
  • valves of fluid being pumped are actuated.
  • the servomotor consists of the housing 31 inside which the hollow plunger 2% is located, provided in its lower part a flanged insert 2% supported by the locating ring 29.
  • a flanged insert 2% supported by the locating ring 29.
  • the orifice of the flanged insert 28 is located slidably the elongated part of the baffle 27 provided with the inlet valve of the fluid, which valve consists of ball l3, pin lid and spring 15 and with the outlet valve of the fluid consisting of steel balls 17 resting on ring 1d.
  • the inlet valve cuts off the space 12 connected with the space lll from the space of the cylinder in, while the outlet valve cuts off the space beneath the plunger l9 from the space of the cylinder lid.
  • the hydraulic piston 22 is located provided with a hollow with the bottom 36.
  • the annular groove 3% connected with the orifice 25 is provided in the cylindrical orifice in which the piston 22 moves.
  • the piston 22 is driven in the operating direction by the piston of the air motor 2 located in the cylinder 5 having on the outer surface the conduit groove connected with orifice d in the cylinder bottom with orifice El leading to the conduit feeding the motor ll.
  • conduit groove 6 is connected by means of the conduit 7 and the tube with the upper surface of the hollow of the plunger 9, in which the pneumatic-hydraulic piston lltl is located.
  • the plunger On the outer surface of the plunger the peripheral groove is provided, in which the sealing ring 33 is placed.
  • the plunger has two different diameters-32 and 3t, whereby the ring space 37 contained between these diameters is permanently connected with the pneumatic conduit supplying the motor by means of the orifice 3b in the in the housing Eli and a conduit (not shown) connecting the orifice 3b and the supply conduit l.
  • the hydraulic space of the plunger Ill is connected by means of conduits hdflfland M with the high-pressure space 19 beneath the plunger.
  • the space M can be separated from the space 19 by cutting off with the needle 5.23 the orifice 25 from the orifice 2d.
  • the peripheral grooveild is provided which is connected by orifices 25 and 2b with the hydraulic space of the plunger ll.
  • the compressed air fed to the conduit 1 penetrates to the air motor 2 and at the same time through the orifice 3 in the conduit l to the conduit 4 in the bottom of the cylinder 5 of the motor 2, then, through the groove 6 to the conduit '7 and further 5 through the tube 8 to the space 9 above the pneumatichydraulic piston 10.
  • the motor 2 On account of the initially low pressure of the compressed air inside the servomotor, the motor 2 still does not operate, but the pneumatic hydraulic piston 10 presses the fluid contained in the space 11, due to which the fluid in the orifice 12 deflects the ball 13 supported by the pin 14 and spring 15 and penetrates to the space 16.
  • the pressure of the compressed air increases and the motor 2 is set into motion.
  • the piston of the motor 2 presses upon the piston 22 and pushes it into the space 16, involving therein a high pressure, due to which the fluid, in the way described previously, penetrates into the space 19 and imparts to the plunger 20 the operating movement under load.
  • the compressed air contained in the space 37 acts permanently upon the plunger in the backward sense.
  • the slidable insert 28 supported by the locating ring 29 has been transversely mounted.
  • An hydraulic servomotor comprising:
  • baffle mounted in said housing and having an elongated axial portion and a recessed area defined in said elongated axial portion, said baffle defining with the walls of said housing first and second hollow interior portions;
  • a hollow plunger mounted in said first hollow interior portion coaxially with said elongated axial portion;
  • connecting means connecting said plunger to said elongated portion for slidable movement of said plunger along said elongated portion
  • first conduit means for supplying air to said motor
  • a piston member mounted in said hollow plunger and defining together with the walls of said plunger a third space, said piston member further defining said first space on the opposite side of said piston member from said third space;
  • third conduit means for communicating said second passageway with said third space.
  • conduit means connecting said first space with said recessed are defined in said elongated axial portion;
  • valve means disposed adjacent the one end of said further conduit means in communication with said recessed area and in engagement therewith, said valve means comprising a ball member and resilient means resiliently urging said ball member into sealing engagement with said one end of said further conduit means, and said resilient means being mounted for engagement with said hydraulic piston.
  • a flanged member disposed in said opening and supported by said annular member and mounted concentrically on said elongated axial portion for slidable movement integrally with said hollow plunger.
  • a servomotor as defined in claim 1 wherein said bafile comprises a hollow cylindrical portion in which said hydraulic piston is mounted for axial movement into and out of said recessed area; an annular groove formed in the walls of said cylindrical portion, and further conduit means defined in said baffle for com municating said annular groove with said second space.
  • said hollow plunger comprises two portions having difierent diameters; the larger diameter corresponding substantially to the internal diameter of said first hollow interior portion, the smaller diameter portion of said plunger defining together with the inside wall of said first hollow interior portion a conduit in permanent communication with said first conduit means.

Abstract

The hydraulic servomotor with air motor is a device which integrates functions performed to date by the big set consisting of hydraulic compound machine, hydraulic conduits, control unit and appropriate servomotor. The servomotor is constructed as an integral unit and consists of the piston air motor of one-sided action and of relatively high frequency running, hydraulic storing system under pressure and appropriate servomotor. By means of these servomotors operating forces of the order of a few to a dozen or so tons could be obtained.

Description

United States Patent Rozwadowski et al.
[ 1 Aug. 29, 1972 HYDRAULIC SERVOMOTOR WITH AIR MOTOR Inventors: Witold Rozwadowski; Aleksander zyrnanski, both of Warsaw, Po land Assignee: Glowne Biuro Studiowi Projektow Zeplecza Technicznego Warszawa, Giviazdzista, Poland Filed: Nov. 17, 1970 Appl. No.: 90,341
Foreign Application Priority Data Nov. 21, 1969 Poland.... ..137030 US. Cl ..60/6, 91/412, 60/97 H, 92/110 Int. Cl. ..F01b 21/00 Field of Search ..92/110, 152; 60/97 H, 6; 91/412 References Cited UNITED STATES PATENTS 8/1894 Palmer ..92/110 3,511,133 5/1970 Day ..92/110 3,426,649 2/1969 Koppers ..91/412 2,701,551 2/1955 Cunning et a1. ..91/412 3,068,841 12/1962 Robbins ..91/412 Primary Examiner-Edgar W. Geoghegan Assistant Examiner-J1. H. Lazarus Attorney-Stevens, Davis, Miller & Mosher ABSTRACT The hydraulic servomotor with air motor is a device which integrates functions performed to date by the big set consisting of hydraulic compound machine, hydraulic conduits, control unit and appropriate servomotor.
The servomotor is constructed as an integral unit and consists of the piston air motor of one-sided action and of relatively high frequency running, hydraulic storing system under pressure: and appropriate servomotor. By means of these servomotors operating forces of the order of a few to a dozen or so tons could be obtained.
10 Claims, 2 Drawing Figures ll lllllfllllhltllllilfi dlEhi/UMUTQR Wl'llli Alll't MUTUR V The present invention relates to an hydraulic servomotor with air motor, which drives an hydraulic piston pump delivering the liquid to operating chamber of a plunger cylinder. v
The design of a hydraulic servomotor with air motor, being applied, particularly, for lifting devices is known up to now. This design, however, has a disadvantage insofar as it makes it difficult to construct servomotors of reduced or miniature size due to the fact, that in the axis of the air motor and of the hydraulic pump connected with it, a pneumatic conduit is located, which serves simultaneously for feeding compressed air to the upper space of the plunger, and for controlling the rotary hydraulic valve provided in the hydraulic conduit that is embraced slidingly by the orifice in the bottom of the hollow plunger.
On the above mentioned pneumatic conduit many intakes of dynamic, pneumatic and hydraulic seals are provided, which fact complicates the design and puts higher requirements as to the resistance of materials used in construction.
At the same time, this design makes it impossible to use hydraulic pistons of pumps of a diameter less than 12 to 15 mm; thus this design cannot be used in constructing small-size motors for higher pressures of the order from 300 to 600 kg/cm, in which the diameter of the hydraulic piston is of the order of 4- to 8 mm.
A further drawback of the design of the hydraulic servomotor with air motor being known at present consists in the fact that the servomotor can operate only in a vertical position, since the fluid level in the plunger is free, while for the regular operation of the servomomotor a constant and perpendicular position of the fluid with respect to the plunger is required.
The purpose of this invention is to eliminate the above mentioned drawbacks and to develop such a design of hydraulic servomotors with air motors, which will permit application of a wide range of diameters of hydraulic pistons, beginning with the values of the order 2 to 3 mm and will ensure at the same time an unchanged position of the fluid level with regard to the plunger.
ln realizing the above object, the pneumatic conduit feeding the compressed air to the upper space of the hollow plunger has been made in the lateral wall surrounding the recess in which the piston of the hydraulic pump is moving.
At the same time the rotary hydraulic valve located in the pump axis has been replaced by the needle valve and arranged transversely in the bottom of the baffle separating the air motor from the space of the plunger cylinder.
To enable this, in the lateral wall surrounding the recess in which the piston of the hydraulic pump moves, a longitudinal orifice has been executed, through which the fluid flows after, opening of the hydraulic needle valve.
In order to secure a steady position of the fluid level with regard to the plunger, the fluid has been separated from the compressed air by a baffle in a form of a tightly fitting piston sliding on the inner surface of the plunger and the outer surface of the pneumatic conduit. I
The hydraulic servomotor with air motor being so designed will permit using it not only for lifting devices,
FlG. ll represents the longitudinal half-section of the hydraulic servomotor with air motor, while MG. 2 shows the cross-section through the outlet,
valves of fluid being pumped.
The servomotor consists of the housing 31 inside which the hollow plunger 2% is located, provided in its lower part a flanged insert 2% supported by the locating ring 29. In the orifice of the flanged insert 28 is located slidably the elongated part of the baffle 27 provided with the inlet valve of the fluid, which valve consists of ball l3, pin lid and spring 15 and with the outlet valve of the fluid consisting of steel balls 17 resting on ring 1d.
The inlet valve cuts off the space 12 connected with the space lll from the space of the cylinder in, while the outlet valve cuts off the space beneath the plunger l9 from the space of the cylinder lid.
in the bottom of the baffle 27 the hydraulic piston 22 is located provided with a hollow with the bottom 36. In the cylindrical orifice in which the piston 22 moves, the annular groove 3% connected with the orifice 25 is provided.
The piston 22 is driven in the operating direction by the piston of the air motor 2 located in the cylinder 5 having on the outer surface the conduit groove connected with orifice d in the cylinder bottom with orifice El leading to the conduit feeding the motor ll.
In the upper part of the cylinder of the motor 5 the conduit groove 6 is connected by means of the conduit 7 and the tube with the upper surface of the hollow of the plunger 9, in which the pneumatic-hydraulic piston lltl is located.
On the outer surface of the plunger the peripheral groove is provided, in which the sealing ring 33 is placed. The plunger has two different diameters-32 and 3t, whereby the ring space 37 contained between these diameters is permanently connected with the pneumatic conduit supplying the motor by means of the orifice 3b in the in the housing Eli and a conduit (not shown) connecting the orifice 3b and the supply conduit l.
The hydraulic space of the plunger Ill is connected by means of conduits hdflfland M with the high-pressure space 19 beneath the plunger. The space M can be separated from the space 19 by cutting off with the needle 5.23 the orifice 25 from the orifice 2d.
in the orifice of the baffle 27 in which the piston 22 moves, the peripheral grooveild is provided which is connected by orifices 25 and 2b with the hydraulic space of the plunger ll.
presses and may As is shown in FIG. 1 the compressed air fed to the conduit 1 penetrates to the air motor 2 and at the same time through the orifice 3 in the conduit l to the conduit 4 in the bottom of the cylinder 5 of the motor 2, then, through the groove 6 to the conduit '7 and further 5 through the tube 8 to the space 9 above the pneumatichydraulic piston 10.
On account of the initially low pressure of the compressed air inside the servomotor, the motor 2 still does not operate, but the pneumatic hydraulic piston 10 presses the fluid contained in the space 11, due to which the fluid in the orifice 12 deflects the ball 13 supported by the pin 14 and spring 15 and penetrates to the space 16.
From the space 16 the fluid through orifices 35 deflects the balls 17 supported by the spring 18 and penetrates into the space 19 beneath the plunger 20 and pushes it from the housing 21.
At the moment the plunger 20 encounters a resistance, the pressure of the compressed air increases and the motor 2 is set into motion. The piston of the motor 2 presses upon the piston 22 and pushes it into the space 16, involving therein a high pressure, due to which the fluid, in the way described previously, penetrates into the space 19 and imparts to the plunger 20 the operating movement under load.
The process described above takes its course in a cycle in a rhythm of the operation of the air motor 2, pumping the fluid from the space 11 to the space 19 under the plunger 20. Upon interruption of the supply of compressed'air to the conduit ll, the motor 2 is stopped. The operating movement of the plunger is stopped too. In consequence, a connection of the conduit 1 with the ambiance causes the disappearing of the pneumatic overpressure inside the servomotor.
The compressed air contained in the space 37 acts permanently upon the plunger in the backward sense.
If now the needle 23 is withdrawn, the spaces 11 and 19 are connected again and the fluid begins to flow from the space 19 through the orifice 24 to the conduit 25 and further through the conduit 26 to the space 11.
. Consequently, the plunger begins to slip inside the housing2l and will finally occupy the extreme outlet position.
In order to make the guidance of the plunger 20 on the elongated part of the baffle 27 independant from the guidance of the plunger in the orifice of the housing 21 in the lower bottom of the plunger, the slidable insert 28 supported by the locating ring 29 has been transversely mounted.
We claim:
1. An hydraulic servomotor, comprising:
a housing;
a baffle mounted in said housing and having an elongated axial portion and a recessed area defined in said elongated axial portion, said baffle defining with the walls of said housing first and second hollow interior portions;
a hollow plunger mounted in said first hollow interior portion coaxially with said elongated axial portion;
connecting means connecting said plunger to said elongated portion for slidable movement of said plunger along said elongated portion;
an air operated motor mounted in said second hollow interior portion;
first conduit means for supplying air to said motor;
an hydraulic piston connected to said motor and mounted for movement within said'recessed area defined in said elongated axial portion;
a first space defined by the interior of said hollow plunger, said elongated axial portion being at least partially disposed within said first space;
a second space defined by said housing, said baffle and a face portion of said hollow plunger; and
second conduit means defined in said baffle for communicating said first and second spaces with each other.
2. A servomotor as defined in claim 1, further comprising:
a first passageway defined in a portion of the wall of said housing which defines said second hollow interior portion;
a second passageway defined in said baffle and connected to said first passageway;
a piston member mounted in said hollow plunger and defining together with the walls of said plunger a third space, said piston member further defining said first space on the opposite side of said piston member from said third space; and
third conduit means for communicating said second passageway with said third space.
3. A servomotor as defined in claim 2, wherein said housing further comprises an end plate which further defines said second hollow interior portion and further comprising a radially disposed conduit defined in said end plate and connecting said first conduit means with said first passageway.
4. A servomotor as defined in claim 2, wherein said third conduit means comprises a hollow tubular member coaxially mounted with said elongated axial portion and connecting said second passageway to said third space and wherein said piston member is slidably mounted on said tubular member and separates said first and third spaces from direct communication with each other.
5. A servomotor as defined in claim 1, further comprising further conduit means defined in a wall of said elongated axial portion for communicating said recessed area with said second space; and valve means engaging said further conduit means comprising a ball member disposed adjacent one end of said further conduit means and resilient means resiliently urging said ball member into sealing engagement with said one end of said further conduit means.
6. A servomotor as defined in claim 1, further comprising:
further conduit means connecting said first space with said recessed are defined in said elongated axial portion; and
valve means disposed adjacent the one end of said further conduit means in communication with said recessed area and in engagement therewith, said valve means comprising a ball member and resilient means resiliently urging said ball member into sealing engagement with said one end of said further conduit means, and said resilient means being mounted for engagement with said hydraulic piston.
7. A servomotor as defined in claim 6, wherein said hydraulic piston comprises an elongated hollow member and said resilient means comprises a spring having one end portion resting in said elongated hollow member and the other end supporting said ball member, and a pin member around which said spring is concentrically mounted.
8. A servomotor as defined in claim 1, wherein said face portion of said hollow plunger has a concentric opening formed therein; and said connecting means comprise:
an annular member mounted in said opening in said face portion; and
a flanged member disposed in said opening and supported by said annular member and mounted concentrically on said elongated axial portion for slidable movement integrally with said hollow plunger.
9. A servomotor as defined in claim 1, wherein said bafile comprises a hollow cylindrical portion in which said hydraulic piston is mounted for axial movement into and out of said recessed area; an annular groove formed in the walls of said cylindrical portion, and further conduit means defined in said baffle for com municating said annular groove with said second space. 10. A servomotor as defined in claim 1, wherein said hollow plunger comprises two portions having difierent diameters; the larger diameter corresponding substantially to the internal diameter of said first hollow interior portion, the smaller diameter portion of said plunger defining together with the inside wall of said first hollow interior portion a conduit in permanent communication with said first conduit means.

Claims (10)

1. An hydraulic servomotor, comprising: a housing; a baffle mounted in said housing and having an elongated axial portion and a recessed area defined in said elongated axial portion, said baffle defining with the walls of said housing first and second hollow interior portions; a hollow plunger mounted in said first hollow interior portion coaxially with said elongated axial portion; connecting means connecting said plunger to said elongated portion for slidable movement of said plunger along said elongated portion; an air operated motor mounted in said second hollow interior portion; first conduit means for supplying air to said motor; an hydraulic piston connected to said motor and mounted for movement within said recessed area defined in said elongated axial portion; a first space defined by the interior of said hollow plunger, said elongated axial portion being at least partially disposed within said first space; a second space defined by said housing, said baffle and a face portion of said hollow plunger; and second conduit means defined in said baffle for communicating said first and second spaces with each other.
2. A servomotor as defined in claim 1, further comprising: a first passageway defined in a portion of the wall of said housing which defines said second hollow interior portion; a second passageway defined in said baffle and connected to said first passageway; a piston member mounted in said hollow plunger and defining together with the walls of said plunger a third space, said piston member further defining said first space on the opposite side of said piston member from said third space; and third conduit means for communicating said second passageway with said third space.
3. A servomotor as defined in claim 2, wherein said housing further comprises an end plate which further dEfines said second hollow interior portion and further comprising a radially disposed conduit defined in said end plate and connecting said first conduit means with said first passageway.
4. A servomotor as defined in claim 2, wherein said third conduit means comprises a hollow tubular member coaxially mounted with said elongated axial portion and connecting said second passageway to said third space and wherein said piston member is slidably mounted on said tubular member and separates said first and third spaces from direct communication with each other.
5. A servomotor as defined in claim 1, further comprising further conduit means defined in a wall of said elongated axial portion for communicating said recessed area with said second space; and valve means engaging said further conduit means comprising a ball member disposed adjacent one end of said further conduit means and resilient means resiliently urging said ball member into sealing engagement with said one end of said further conduit means.
6. A servomotor as defined in claim 1, further comprising: further conduit means connecting said first space with said recessed are defined in said elongated axial portion; and valve means disposed adjacent the one end of said further conduit means in communication with said recessed area and in engagement therewith, said valve means comprising a ball member and resilient means resiliently urging said ball member into sealing engagement with said one end of said further conduit means, and said resilient means being mounted for engagement with said hydraulic piston.
7. A servomotor as defined in claim 6, wherein said hydraulic piston comprises an elongated hollow member and said resilient means comprises a spring having one end portion resting in said elongated hollow member and the other end supporting said ball member, and a pin member around which said spring is concentrically mounted.
8. A servomotor as defined in claim 1, wherein said face portion of said hollow plunger has a concentric opening formed therein; and said connecting means comprise: an annular member mounted in said opening in said face portion; and a flanged member disposed in said opening and supported by said annular member and mounted concentrically on said elongated axial portion for slidable movement integrally with said hollow plunger.
9. A servomotor as defined in claim 1, wherein said baffle comprises a hollow cylindrical portion in which said hydraulic piston is mounted for axial movement into and out of said recessed area; an annular groove formed in the walls of said cylindrical portion, and further conduit means defined in said baffle for communicating said annular groove with said second space.
10. A servomotor as defined in claim 1, wherein said hollow plunger comprises two portions having different diameters, the larger diameter corresponding substantially to the internal diameter of said first hollow interior portion, the smaller diameter portion of said plunger defining together with the inside wall of said first hollow interior portion a conduit in permanent communication with said first conduit means.
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US524184A (en) * 1894-08-07 John p
US2701551A (en) * 1952-02-20 1955-02-08 Westinghouse Air Brake Co Automatic air feed pressure control for rock drills
US3068841A (en) * 1961-01-13 1962-12-18 Robbins & Bendror Associates I Hydraulic pressure system
US3426649A (en) * 1963-11-29 1969-02-11 Rheinstahl Wanheim Gmbh Multistage hydraulic mine prop
US3511133A (en) * 1968-03-06 1970-05-12 Caterpillar Tractor Co Position control for hydraulic jacks

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US524184A (en) * 1894-08-07 John p
US2701551A (en) * 1952-02-20 1955-02-08 Westinghouse Air Brake Co Automatic air feed pressure control for rock drills
US3068841A (en) * 1961-01-13 1962-12-18 Robbins & Bendror Associates I Hydraulic pressure system
US3426649A (en) * 1963-11-29 1969-02-11 Rheinstahl Wanheim Gmbh Multistage hydraulic mine prop
US3511133A (en) * 1968-03-06 1970-05-12 Caterpillar Tractor Co Position control for hydraulic jacks

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Publication number Publication date
HU163544B (en) 1973-09-27
PL80403B3 (en) 1975-08-30
DE2056936A1 (en) 1971-06-16
DE2056936B2 (en) 1977-02-17
FR2068570A1 (en) 1971-08-27
CS172917B2 (en) 1977-01-28
AT308327B (en) 1973-06-25
FR2068570B1 (en) 1973-02-02

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