US1724184A - Automatic hydraulic press - Google Patents
Automatic hydraulic press Download PDFInfo
- Publication number
- US1724184A US1724184A US146504A US14650426A US1724184A US 1724184 A US1724184 A US 1724184A US 146504 A US146504 A US 146504A US 14650426 A US14650426 A US 14650426A US 1724184 A US1724184 A US 1724184A
- Authority
- US
- United States
- Prior art keywords
- pressure chamber
- fabric
- ram
- casing
- bed
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B30—PRESSES
- B30B—PRESSES IN GENERAL
- B30B9/00—Presses specially adapted for particular purposes
- B30B9/02—Presses specially adapted for particular purposes for squeezing-out liquid from liquid-containing material, e.g. juice from fruits, oil from oil-containing material
- B30B9/04—Presses specially adapted for particular purposes for squeezing-out liquid from liquid-containing material, e.g. juice from fruits, oil from oil-containing material using press rams
- B30B9/06—Presses specially adapted for particular purposes for squeezing-out liquid from liquid-containing material, e.g. juice from fruits, oil from oil-containing material using press rams co-operating with permeable casings or strainers
-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23G—COCOA; COCOA PRODUCTS, e.g. CHOCOLATE; SUBSTITUTES FOR COCOA OR COCOA PRODUCTS; CONFECTIONERY; CHEWING GUM; ICE-CREAM; PREPARATION THEREOF
- A23G1/00—Cocoa; Cocoa products, e.g. chocolate; Substitutes therefor
- A23G1/04—Apparatus specially adapted for manufacture or treatment of cocoa or cocoa products
- A23G1/08—Cocoa butter presses
Definitions
- the invention relates to an automatic hydraulically operated press for the extraction of oils from seeds or fruit in which the ad mission and exhaust of the pressure on the different pistons, the insertion of the filter ing fabric or fabrics, the ejection of the oil cake-from the press and the setting of the press for a new cycle of operations are auto- .matic.
- the invention consists in the filtering fabric being arranged in front of a bed for the movable pressure chamber and-in means for moving said fabric out of the pressure chamber together with the pressed oil cake. Furthermoreaccording to the invention the ram after having pressed the oil cake begins its backward motion first, and then the pressure chamber returns to its initial position, the
- I Fig. 1 is a part elevation, part vertical section of the whole of thepress and of its accessory parts.-
- Fig. 2 is a cross view with part-section through the casing E for one half and through the casing F for the other half.
- Fig. 3 is avertical section of an-alternative construction of the piston-head I.
- the apparatus comprises:
- a frameworkA supporting a cylinder B and a bed C stayed by two columns D.
- bis metal casing can be brought against the ressure ex- "erted, and the time during which it is apbed 0, by means of the pawns o placed symmetrically to the horizontal axis of the press.
- the pistons H with invariable ressure tend to hold the casing E, F away rom the bed C; the action of the pistons G being more powerful when they receive the hydraulic pressure, the casing F is pressed against the bed C.
- a pressing piston I slides inside the cylinder B, and is brought back bythe rods K connecting it with the constant pressure cylinder J sliding on the piston L when the pressure of the piston I is shut off.
- the piston I enters the portion F of the casing to compress the material to be treated placed against the filtering fabric T itself placed next to the perforated plate Q.
- the portion E of the casing has an inner annular perforated wall E the holes in which lead into a circular channel M conveying the liquids to a nozzle N through which theyflow away.
- the part F of the casing cylindrical in its lower half, runs up in two parallel sides in its second half, the top part of which is open and communicates with a piping O, bringing'the parts to be pressed, the latter coming from a heater P, for instance.
- the bed C carries a perforated plate Q, the holes in which. lead to vertical channels B which allow the liquids to escape outside the filtering casing.
- a valve controller Z operates by cams on the pressure exhaust flapsof the pistons G and It should be noticed that the pistons H. and L are under constant pressure and only come into action when the pressure of the pistons G and I ceases.
- the press may be doubled by fitting similar organs on both sides of the cylinder B, the latter containing in this case, two pressing pistons I opposed to each othe and moving simultaneously in opposite directions.
- the press acts as follows:
- the metal casing E. F. being filled with the material to be pressed, the corresl'mnding cam of the valve controller Z raises the pressure-admission flap-valve into the cyliuder B.
- the piston I enters part F of the casing, closes the inlet of'the paste, enters part E of the casing, and there starts to strongly compress the matter.
- the liquid runs out through the perforated wall E into the groove M and through the nozzle N into the tray A,.
- the clutching of the pulley U allows the driving of the drum S, which pulls upwards the fabric T, thus raising the oil-cake into the funnel D,; the fabric coiling itself round the drum S tears itself away from the oilcake, the latter being maintained during its upward motion in the funnel D against the side d, tangential to the drums.
- the oil'cake could also, by spontaneous parting from the fabric T, fall into the lower part.
- Fig. 3 shows a different construction of part of the apparatus, the piston I being fitted with a perforated plate M the holes in which lead into vertical channels thence into a circular groove N,, from which the liquids flow out of the casing, by way of the pipe 0,.
- the fabric L will resume its position by its own weight, as the fabric T returns into position.
- an automatic hydraulically operated press for extraction of oil from seeds and fruit, a ram, a movable pressure chamber for said ram, a bed for the pressure chamber carrying a perforated plate allowing liquid to escape from the pressure chamber, a filtering fabric arranged in front of the perforated plate of the bed, means for moving said fabric to and fro upwards anddownwards and from out of the pressure chamber, hydraulic means for moving said ram into the pressure chamber and withdrawing the fabric to be pulled upwards togetherwith the adhering oilcake, and means for controlling the motion of the fabric and giving it but once the to and fro motion only after the pressure chamber being removed from its bed. 7
- a ram In an automatic hydraulically operated press for extraction of oil from seeds and fruit, a ram, a movable pressure chamber for said ram, a bed for the pressure chamber, carrying a perforated plate allowing liquid to escape from the pressure chamber a filtering fabric arranged in front of the perforated plate-of the bed, means for moving said fabric to and fro upwards and downwards and from out of the pressure chamber, hydraulic means for moving said ram into the pressure chamber and withdrawing from the latter, hydraulic means for moving the pressure chamber to and fro, an inlet opening for material to be pressed provided in the wall of the pressure chamber and to be controlled by the ram, means for admitting the hydraulic pressure onto the ram and onto the pressure chamber in such a way that the ram after having pressed the oil cake begins its backward motion first and then the pressure chamber is returning to its initial position whereby the speed of the pressure chamber exceeds the speed of the ram, thus enabling the fabric to be drawn u, awards together with the adhering oilcake, and means for controlling the motion of
- a ram having at its front end a perforated plate for the escape of liquid, a filtering fabric having one edge, attached to the upper part of the front surface of the ram and laying against said front surface, a movable pressure chamber for said ram, a bed for the pressure chamber, carrying a perforated plate allowing liquid to escape from the pressure chamber, a second filtering fabric arranged in front of the perforated plate of the bed, means for moving said second fabric upwards and from out of the pres sure chamber, hydraulic means formoving said ram into the pressure chamber and with drawing from the latter, hydraulic means for moving the pressure chamber to and fro, an inlet opening for material to be pressed pro viding in the wall of the pressure, chamber and to be controlled by the ram, means for a dmitting the hydraulic pressure onto the ram and onto the pressure chamber in such a way that the ram after having pressed the oil cake begins its backwards motion first and then the pressure chamber
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Food Science & Technology (AREA)
- Polymers & Plastics (AREA)
- Filtration Of Liquid (AREA)
- Treatment Of Fiber Materials (AREA)
- Apparatuses For Bulk Treatment Of Fruits And Vegetables And Apparatuses For Preparing Feeds (AREA)
Description
Aug. 13, 1929. L. c. DEOUNE AUTOMATIC HYDRAULIC PRESS Filed Nov. 5, 1926 2 Sheets-Shem 1 INVENTOR 27 in: C'Jkaune,
Aug. 13, 1929. 1.. c. DEOUNE AUTOMATIC HYDRAULIC PRESS Filed Nov. 5, 1926 asneets-sheex Patented Au 13, 1929.
UNITED STATES LEOII CHARLES DEE-DUNE, F MABSEILLE, FRANCE, ASSIGNOR TO SOCIE'IE ANONYEE DES ATELIERS ARMANI) 8c DEOUNE, A COMPANY 01 FRANCE.
AUTOMATIC HYDRAUIIIG PRESS.
. Application filed November 5, 1926, Serial No. 146,504, and in France. November 23. '192 The invention relates to an automatic hydraulically operated press for the extraction of oils from seeds or fruit in which the ad mission and exhaust of the pressure on the different pistons, the insertion of the filter ing fabric or fabrics, the ejection of the oil cake-from the press and the setting of the press for a new cycle of operations are auto- .matic.
The invention consists in the filtering fabric being arranged in front of a bed for the movable pressure chamber and-in means for moving said fabric out of the pressure chamber together with the pressed oil cake. Furthermoreaccording to the invention the ram after having pressed the oil cake begins its backward motion first, and then the pressure chamber returns to its initial position, the
speed of the pressure chamber exceeding the speed of the ram.
The apparatus as invented includes the following advantages:
Speedy extraction of the liquids. Eliminates the loose sheets or absorbing materials in which the matter to be pressed is sometimes wrapped.
Elimination of the parings or edges of the oil-cakes not completely exhausted.
Renders uselessthe so-called preparatory presses.
Possibility of treating any matter out of which the liquid parts are to be extracted; the liquid obtained being in every case quite clear and pure.
Possibility of altering the plied, according to the result desired.
Very high pressure.
Elimination of considerable labour.
The attached drawings show a preferred embodiment of the invention, in which,
I Fig. 1 is a part elevation, part vertical section of the whole of thepress and of its accessory parts.-
Fig. 2 is a cross view with part-section through the casing E for one half and through the casing F for the other half.
Fig. 3 is avertical section of an-alternative construction of the piston-head I.
The apparatus comprises:
A frameworkA supporting a cylinder B and a bed C stayed by two columns D.
A filtering metal casing composed of two parts E and F, slides on the columns D.
bis metal casing can be brought against the ressure ex- "erted, and the time during which it is apbed 0, by means of the pawns o placed symmetrically to the horizontal axis of the press.
The pistons H, with invariable ressure tend to hold the casing E, F away rom the bed C; the action of the pistons G being more powerful when they receive the hydraulic pressure, the casing F is pressed against the bed C.
A pressing piston I slides inside the cylinder B, and is brought back bythe rods K connecting it with the constant pressure cylinder J sliding on the piston L when the pressure of the piston I is shut off.
The piston I enters the portion F of the casing to compress the material to be treated placed against the filtering fabric T itself placed next to the perforated plate Q.
The portion E of the casing has an inner annular perforated wall E the holes in which lead into a circular channel M conveying the liquids to a nozzle N through which theyflow away. i
The part F of the casing, cylindrical in its lower half, runs up in two parallel sides in its second half, the top part of which is open and communicates with a piping O, bringing'the parts to be pressed, the latter coming from a heater P, for instance.
The bed C carries a perforated plate Q, the holes in which. lead to vertical channels B which allow the liquids to escape outside the filtering casing.
Between the casing E and the plate Q, is interposeda filtering fabric T, attached to the two revolving drums S and S The upper drum S is driven by a known planet-gear, allowing by means of the braking of the drum U through a steel ribbon The lower drum S turns loose on the bearings and receives 'the filtering fabric T, which it rolls up by means of the counterweight V and of the cables X coiled round the axle y of the drum S. e
A valve controller Z operates by cams on the pressure exhaust flapsof the pistons G and It should be noticed that the pistons H. and L are under constant pressure and only come into action when the pressure of the pistons G and I ceases.
Two trays A and A are slung under the framework A, in order to receive the liquids which afterwards run, through the pipe B into the channel C A sheet-iron box 1),, acting as conveying funnel for the oil-cake E carries inside a flap F maintained in its closed position by the springs G and G H is a rotary brush to clear the filtering fabric T at each motion.
The press may be doubled by fitting similar organs on both sides of the cylinder B, the latter containing in this case, two pressing pistons I opposed to each othe and moving simultaneously in opposite directions.
The press acts as follows:
The metal casing E. F. being filled with the material to be pressed, the corresl'mnding cam of the valve controller Z raises the pressure-admission flap-valve into the cyliuder B.
The piston I enters part F of the casing, closes the inlet of'the paste, enters part E of the casing, and there starts to strongly compress the matter.
The liquid runs out through the perforated wall E into the groove M and through the nozzle N into the tray A,.
It also runs through the fabric '1, through the holes of the plate Q, into the grooves R which drip into the tray A The time of the pressure being regulated by the speed of the cam-shaft of the valve controller Z, the cylinder B begins to empty and the piston I goes back to its initial position, thus parting from the oil-cake made. As soon as this parting is completed, the valve controller Z, always by means of a cam, stops the hydraulic pressure on the piston G and the casing E. F. slides back under the uninterrupted action of the piston H.
The backward movement of the casing EF is quicker than that of the ram 1; the stop J, on this casing immediately pulling the levers I and H,, which clutch in the brake composed of a steel tape rolled on the pulley U.
The clutching of the pulley U allows the driving of the drum S, which pulls upwards the fabric T, thus raising the oil-cake into the funnel D,; the fabric coiling itself round the drum S tears itself away from the oilcake, the latter being maintained during its upward motion in the funnel D against the side d, tangential to the drums.
The oil-cake having passed the sloping flap F the latter falls back, prompted by the springs Gr and Gr and the unhampered oil-cake rollsdown the slope of F which motion delivers it out of the apparatus.
The oil'cake could also, by spontaneous parting from the fabric T, fall into the lower part.
During the ascending motion of the oilcake, the fabric T forces, by means of the stop K,, the arm I and raises the lever I which frees itself from the catch J,. The pulley U is no longer driven, becomes loose and frees the drum S, which stops, and starts moving in the opposite direction, the fabric T moving backwards, under the action of the drum S actuated by the counterweight V.
The fabric T having returned to its starting position, the ram I, which was slowly sliding back, uninasks at this movement the inlet for the paste, whereas the valve controller Z sets in action the piston G, bringing the casing E. F. back against the bed C.
The paste falls into the casing and everything is now, ready for another operating cycle as soon as the corresponding cam of the valve controller Z opens the flap-valve allowing pressure on the ram I.
Fig. 3 shows a different construction of part of the apparatus, the piston I being fitted with a perforated plate M the holes in which lead into vertical channels thence into a circular groove N,, from which the liquids flow out of the casing, by way of the pipe 0,.
In this case a filtering fabric L is fixed on the top part of the ram I; the matter is thus pressed between two layers of filtering fabric placed on perforated metal surfaces.
In the upward motion of the oil-cake, the filtering fabric L will loosen itself from it, by folding, as shown on Fig. 3.
The fabric L will resume its position by its own weight, as the fabric T returns into position.
I claim:
1. In an automatic hydraulically operated press for extraction of oil from seeds and fruit, a ram, a movable pressure chamber for said ram, a bed for the pressure chamber carrying a perforated plate allowing liquid to escape from the pressure chamber, a filtering fabric arranged in front of the perforated plate of the bed, means for moving said fabric to and fro upwards anddownwards and from out of the pressure chamber, hydraulic means for moving said ram into the pressure chamber and withdrawing the fabric to be pulled upwards togetherwith the adhering oilcake, and means for controlling the motion of the fabric and giving it but once the to and fro motion only after the pressure chamber being removed from its bed. 7
2. In an automatic hydraulically operated press for extraction of oil from seeds and fruit, a ram, a movable pressure chamber for said ram, a bed for the pressure chamber, carrying a perforated plate allowing liquid to escape from the pressure chamber a filtering fabric arranged in front of the perforated plate-of the bed, means for moving said fabric to and fro upwards and downwards and from out of the pressure chamber, hydraulic means for moving said ram into the pressure chamber and withdrawing from the latter, hydraulic means for moving the pressure chamber to and fro, an inlet opening for material to be pressed provided in the wall of the pressure chamber and to be controlled by the ram, means for admitting the hydraulic pressure onto the ram and onto the pressure chamber in such a way that the ram after having pressed the oil cake begins its backward motion first and then the pressure chamber is returning to its initial position whereby the speed of the pressure chamber exceeds the speed of the ram, thus enabling the fabric to be drawn u, awards together with the adhering oilcake, and means for controlling the motion of the fabric and giving it but once the up and down motion only after the pressure chamber being removed from its bed.
3. In an automatic hydraulically operated press for extraction of oil from seeds and fruit, a ram, a movable pressure chamber for said ram, a bed for the pressure chamber, carrying a perforated plate allowing liquid to escape from the pressure chamber, a filtering fabric arranged in front of the perforated plate of the bed, means for m ving said fabric upwards and from out of the pressure chamber, hydraulic means for moving said ram into the pressure chamber and with drawing from the latter, hydraulic means for moving the pressure chamber to and fro, an inlet opening for material to be pressed provided in the wall of the pressure chamber and to be controlled by the ram, means for admitting the hydraulic pressure onto the ram and onto the pressurechamber in such a way that the ram after having pressed the oil cake begins its backward motion first and then the p: ssure chamber is returning to its initial position whereby the speed of the pressure chamber exceeds the speed of the ram, thus enabling the fabric to be drawn upwards together with the adhering oil cake, each end of the filtering'fabric being fixed to a revolving drum, one of them arranged above and the other one arranged beneath the pressure chamber, the movement of the drums being controlled by stops pivotally mounted on the pressure chamber and means for driving the drums alternatively in both directions but only after the pressure chamher being removed from its bed.
l. In an automatic hydraulically operated press for extraction of oil from seeds and fruit, a ram having at its front end a perforated plate for the escape of liquid, a filtering fabric having one edge, attached to the upper part of the front surface of the ram and laying against said front surface, a movable pressure chamber for said ram, a bed for the pressure chamber, carrying a perforated plate allowing liquid to escape from the pressure chamber, a second filtering fabric arranged in front of the perforated plate of the bed, means for moving said second fabric upwards and from out of the pres sure chamber, hydraulic means formoving said ram into the pressure chamber and with drawing from the latter, hydraulic means for moving the pressure chamber to and fro, an inlet opening for material to be pressed pro viding in the wall of the pressure, chamber and to be controlled by the ram, means for a dmitting the hydraulic pressure onto the ram and onto the pressure chamber in such a way that the ram after having pressed the oil cake begins its backwards motion first and then the pressure chamber in returning to its initial position whereby the speed of the pressure chamber exceeds the speed ofthe ram, thus enabling the second filtering fabric to be drawn upwards together with the adhering oil cake, each end of the second filtering fabric being fixed to a revolving drum, one of them arranged above and the other one arranged beneath the pressure chamber, the movement of the drums being controlled by stops pivotally mounted on the pressure chamber and on the second filtering fabric and means for driving the drums alternatively in both directions but only after the pressure chamber being removed from its bed.
In testimony whereof I have affixed my signature.
LEON CHARLES DEOUNE.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR465950X | 1925-11-26 |
Publications (1)
Publication Number | Publication Date |
---|---|
US1724184A true US1724184A (en) | 1929-08-13 |
Family
ID=8902142
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US146504A Expired - Lifetime US1724184A (en) | 1925-11-26 | 1926-11-05 | Automatic hydraulic press |
Country Status (5)
Country | Link |
---|---|
US (1) | US1724184A (en) |
BE (1) | BE337049A (en) |
DE (1) | DE465950C (en) |
FR (1) | FR619392A (en) |
GB (1) | GB262072A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN107825741A (en) * | 2017-10-30 | 2018-03-23 | 钟光文 | A kind of medical and beauty treatment plant essence liquid high efficiency extraction equipment |
CN110406147A (en) * | 2019-07-02 | 2019-11-05 | 广州贤智科技有限公司 | A kind of heavy duty detergent solid-liquid separating machine for organic fertilizer production |
CN114770676A (en) * | 2022-06-20 | 2022-07-22 | 启东市罗源光伏设备有限公司 | Constant-pressure press and application thereof in cold pressing process of plates |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1109501B (en) * | 1954-12-11 | 1961-06-22 | Hydraulik Gmbh | Process for pressing cocoa masses and cocoa pot press to carry out the process |
IT208248Z2 (en) * | 1986-10-16 | 1988-04-22 | Ferrero Spa | PRESS FOR PRESSING COCOA PASTA |
CN112959716A (en) * | 2021-02-20 | 2021-06-15 | 柳州城市职业学院 | Tea bran autosegregation machine with tea-seed oil is collected |
-
0
- BE BE337049D patent/BE337049A/xx unknown
-
1925
- 1925-11-26 FR FR619392D patent/FR619392A/en not_active Expired
-
1926
- 1926-11-01 GB GB27281/26A patent/GB262072A/en not_active Expired
- 1926-11-05 US US146504A patent/US1724184A/en not_active Expired - Lifetime
- 1926-11-12 DE DES76950D patent/DE465950C/en not_active Expired
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN107825741A (en) * | 2017-10-30 | 2018-03-23 | 钟光文 | A kind of medical and beauty treatment plant essence liquid high efficiency extraction equipment |
CN107825741B (en) * | 2017-10-30 | 2019-05-10 | 南京阳子生物科技有限公司 | A kind of medical and beauty treatment plant essence liquid high efficiency extraction equipment |
CN110406147A (en) * | 2019-07-02 | 2019-11-05 | 广州贤智科技有限公司 | A kind of heavy duty detergent solid-liquid separating machine for organic fertilizer production |
CN110406147B (en) * | 2019-07-02 | 2021-06-01 | 广州贤智科技有限公司 | A high-efficient type solid-liquid separation machine for organic fertilizer production |
CN114770676A (en) * | 2022-06-20 | 2022-07-22 | 启东市罗源光伏设备有限公司 | Constant-pressure press and application thereof in cold pressing process of plates |
Also Published As
Publication number | Publication date |
---|---|
DE465950C (en) | 1928-09-28 |
FR619392A (en) | 1927-03-31 |
BE337049A (en) | |
GB262072A (en) | 1928-02-01 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US1724184A (en) | Automatic hydraulic press | |
US4405457A (en) | Plate-type filter press with a cleaning truck | |
US5365838A (en) | Machine for the extraction of juice from grapes | |
JPS602889B2 (en) | Discontinuous filtration method and device for suspensions | |
NO157372B (en) | DEVICE FOR AA EXPRESSING LIQUID OF A MOISTURED MASS AND PROCEDURE FOR CONTINUOUS EXPOSURE OF LIQUID FROM A MOISTURED MASS BY COMPRESSING THE MASS. | |
US2554968A (en) | Continuous pressure separating device operating in multiple stages | |
DE3041994A1 (en) | METHOD FOR DRAINING A LOT OF LOT | |
US3256721A (en) | Press for textile goods | |
US2072942A (en) | Press | |
US4377479A (en) | Vacuum belt filter | |
US3154228A (en) | Drapery pleating and pressing machine | |
US2476574A (en) | Baling press | |
US883536A (en) | Machine for extracting liquid from cloth. | |
US2997179A (en) | Sifting device and method for filtering with the aid of said sifting device | |
US2038721A (en) | Machine for the production of molded pulp articles | |
US2659412A (en) | Means and method for producing a continuous sheet of integrated mica | |
US2050191A (en) | Machine for adhesively uniting the plies of multiple ply articles of apparel | |
US4392422A (en) | Apparatus for removing liquid from a suspension | |
US1742470A (en) | Press | |
US1476532A (en) | Preservation and preparation for transportation of cottonseed | |
US1980000A (en) | Oil press | |
US2027252A (en) | Steeping peess | |
US1481838A (en) | Apparatus por expressing | |
US413683A (en) | William p | |
DE1955238A1 (en) | Device for controlling the movement of a piston in its end position which can be displaced in a cylinder under the action of a pressure medium |