DE102010050301A1 - Cast blank for cylinder tube of hydraulic cylinder, comprises near-net-shape portion formed with cast blank in one-piece manner for attaching or receiving hydraulic functional element at its outer circumference of storage equipment - Google Patents

Abstract

The cast blank for a cylinder tube (1) of a hydraulic cylinder, comprises a near-net-shape portion formed with the cast blank in an one-piece manner for attaching or receiving a hydraulic functional element at its outer circumference of a storage equipment comprising a pivot pin for fastening, supporting or storing the hydraulic cylinder. The portion is a connection (14' 16'), a connection surface, a connection recess (10'), a through hole recess (12'), a connection pin, a connection flange, a connection plate (6'), a hydraulic control block, a valve housing or a cylinder tube sheet. The cast blank for a cylinder tube (1) of a hydraulic cylinder, comprises a near-net-shape portion formed with the cast blank in an one-piece manner for attaching or receiving a hydraulic functional element at its outer circumference of a storage equipment comprising a pivot pin for fastening, supporting or storing the hydraulic cylinder. The portion is a connection (14' 16'), a connection surface, a connection recess (10'), a through hole recess (12'), a connection pin, a connection flange, a connection plate (6'), a hydraulic control block, a valve housing, a cylinder tube sheet, a rib or a threaded portion. The hydraulic function element is a hydraulic line, a pressure medium channel, a pressure medium container, the hydraulic control block, the valve, a pressure relief valve, a way valve, a lowering brake valve, a pressure measuring unit, a hydraulic pump, an electric motor, a position sensor, linear encoder of a displacement measuring unit or a cover plate. Independent claims are included for: (1) a method for producing cylinder tube of a hydraulic cylinder over the casting blank; and (2) a cylinder tube for a hydraulic cylinder.

Description

The invention relates to a casting blank for a cylinder tube of a hydraulic cylinder according to the preamble of claim 1, and the cylinder tube and a method for producing the cylinder tube.

A cylinder tube of a hydraulic cylinder generally has several parts of different function. It has a circular cylindrical interior, which is formed, for example, via a tube in which a piston is received axially movable, a cylinder tube bottom, which closes the interior or the tube axially at one end portion, connections to which, for example, pressure medium lines or valves can be connected, etc In general, sections must be present on or in the cylinder tube to which a hydraulic functional element can be attached or attached or received.

It is known to add these parts or sections via a welded joint to produce the cylinder tube.

The disadvantage of this is that the welding on the one hand represents a high cost and on the other hand, a potential weak point of the cylinder tube is formed on the weld joint. In addition, the supplied thermal energy can adversely affect the dimensional stability of the interior.

Alternatively, it is known to form the cylinder tube from a solid material or cast block via separating methods, such as drilling, turning or milling.

This is adversely associated with a high material usage, a high processing cost and, since weight-optimal material or wall thicknesses can only be reached via an increased processing costs, usually a large weight of the cylinder tube.

The DE 3835383 A1 proposes as an alternative to the two variants, a method in which a casting blank for a cylinder tube of semi-liquid metal or semi-solid metal starting material is poured. About a casting mold or one or more casting cores while the parts (pressure medium channels, sniffer holes, connections, recesses, systems) are precast in a rough shape to the casting blank. The casting blank is brought into the final shape or into the final contour of the cylinder tube by subsequent cutting or machining such as stamping, milling or drilling. This method and the disclosed cylinder tube is proposed in particular for master cylinder of vehicle technology.

The disadvantage of this is a further high processing costs by punching and machining processes.

In contrast, the invention is based on the object to provide a cast blank for a cylinder tube, from which the cylinder tube can be manufactured with a reduced machining effort.

This object is achieved by a cast blank having the features of patent claim 1.

Advantageous developments of the invention are described in the dependent claims.

A casting blank for a cylinder tube of a hydraulic cylinder, on the outer circumference of which a bearing device for fastening, supporting or supporting the hydraulic cylinder is provided, has, according to the invention, a section shaped approximately close to the casting blank, which is formed on or in a cylinder tube made from the casting blank in a final contour is provided for attaching or fastening or for receiving a hydraulic functional element.

As a result, a later processing effort for the formation of the final contour or the cylinder tube is reduced, since no material or only very little material must be separated from the casting blank to form the final contour. The application according to the invention is to be understood as meaning that the hydraulic functional element can be fastened to the section or connected to the section, for example to form a pressure medium connection. The recording according to the invention also means that the hydraulic functional element is formed at least in sections within the section or arranged within the section.

The section of the cast blank may be a connection or a connection surface or a connection recess or a through-hole or a connection pin or a connection flange or a connection plate or a hydraulic control block or a hydraulic block or a hydraulic plate or a valve housing or a cylinder tube bottom or a rib or a threaded portion.

Since the said sections in the casting blank are close to the final contour and are integrally integrated in it, they no longer have to be integrated into the cylinder tube to be manufactured later via joining methods, such as welding. That lowers the Effort for the production of the cylinder tube and at the same time increases its stability, since weakening joints or welds omitted.

The hydraulic functional element, for the preparation of which the section is shaped close to the final contour, is preferably a hydraulic line or a pressure medium channel or a pressure medium container or a hydraulic control block or a valve or a pressure limiting valve or a directional valve or a lowering brake valve or a pressure measuring unit or a hydraulic pump or a Electric motor, via which the hydraulic pump is driven, or a displacement sensor or a displacement sensor of a displacement measuring unit of the hydraulic cylinder or a cover plate of the cylinder tube.

• – die an den Anschluss oder an die Anschlussplatte anzusetzende bzw. anzuschließende Druckmittelleitung,
• – das an die Anschlussplatte anzusetzende bzw. anzuschließende Ventil,
• – der an die Anschlussplatte anzusetzende bzw. anzuschließende hydraulische Steuerblock oder Hydraulikblock oder die an die Anschlussplatte anzusetzende bzw. anzuschließende Hydraulikplatte,
• – der in der Rippe aufzunehmende Druckmittelkanal,
• – das am Zylinderrohrboden anzusetzende bzw. anzuschließende oder im Zylinderrohrboden abschnittsweise aufzunehmende Wegeventil,
• – die am Zylinderrohrboden anzusetzende bzw. anzuschließende oder im Zylinderrohrboden abschnittsweise aufzunehmende Hydropumpe. Vorteilhaft ist die Aufnahme der Hydropumpe, wenn das Zylinderrohr bzw. der Hydraulikzylinder mit ausreichend hohen Stückzahlen hergestellt wird. Alternativ dazu und insbesondere im Falle geringerer Stückzahlen des Zylinderrohres bzw. Hydraulikzylinders kann eine Standardpumpe am Zylinderrohrboden anzusetzen bzw. zu befestigen sein,
• – der am Zylinderrohrboden anzusetzende bzw. zu befestigende Elektromotor, über den die Hydropumpe anzutreiben ist,
• – die am Zylinderrohrboden anzusetzende bzw. zu befestigende oder zumindest abschnittsweise aufzunehmende Druckmesseinheit,
• – der am Zylinderrohrboden anzusetzende bzw. zu befestigende oder zumindest abschnittsweise aufzunehmende Weggeber oder Wegsensor der Wegmesseinheit.

Particularly preferred combinations of the section with the functional element to be attached thereto or incorporated therein are:

• - The pressure medium line to be attached to or connected to the connection or to the connection plate,
• The valve to be attached to the connection plate or to be connected,
• The hydraulic control block or hydraulic block to be attached to or to be connected to the connection plate or the hydraulic plate to be attached or to be connected to the connection plate,
• The pressure medium channel to be received in the rib,
• The directional valve to be attached to the cylinder tube bottom or to be connected in sections in the cylinder tube bottom,
• - To be applied to the cylinder tube bottom or to be connected or in the cylinder tube bottom sections to be included hydraulic pump. Advantageously, the inclusion of the hydraulic pump when the cylinder tube or the hydraulic cylinder is manufactured with sufficiently high numbers. Alternatively, and in particular in the case of lesser quantities of the cylinder tube or hydraulic cylinder, a standard pump may be attached to the cylinder tube bottom or fastened,
• The electric motor to be attached to the cylinder tube base or via which the hydraulic pump is to be driven,
• The pressure measurement unit to be attached to the cylinder tube bottom or to be attached at least in sections,
• - The position to be attached to the cylinder tube bottom or to be fastened or at least partially recorded Weggeber or displacement sensor of the displacement measuring unit.

For attachment or for fastening of the functional element, the cylinder tube bottom of the cast blank preferably has a substantially planar surface, formed radially or axially, with a near net shape.

In an advantageous development and in order to further reduce the machining effort of the cast blank for forming the bearing device of the cylinder tube or of the hydraulic cylinder, the cast blank has a near-net shape and integrally formed pivot pin.

In order to obtain a low-temperature strength down to -40 ° C, the casting blank preferably consists of cast steel. Particularly advantageous is its cold-strength property in an application of the hydraulic cylinder in applications outside of buildings and with high mechanical loads. Such requirements must meet, for example, a control cylinder in a wind turbine. If, on the other hand, a lower low-temperature strength up to about -20 ° C is required, the cast blank may consist of less expensive and less expensive ductile iron to be processed.

• a. Gießen des erfindungsgemäßen Gussrohlings;
• b. Fertigen des Zylinderrohres, insbesondere über ein trennendes oder spanabhebendes Fertigungsverfahren.

A preferred method for producing the cylinder tube has the following steps:

• a. Casting the cast blank according to the invention;
• b. Finishing of the cylinder tube, in particular via a separating or cutting production process.

The section for attachment or for receiving the hydraulic functional element is in step a. Pouring preferably formed over a near-net shape formed mold.

In a preferred embodiment of the method and in order to form recesses within the sections, they are also formed over end cores formed casting cores. This reduces the production effort for step b. Final.

In an advantageous development of the method, a feeder of the casting mold before step a. Casting arranged in the region of an intended, for example, functional reasons accumulation of material of the casting blank, provided that this area is subjected to a lower mechanical stress on the later cylinder tube. The feeder can be provided for example in the region of the pressure medium connection of the cylinder tube, to which a low-pressure tank is connected, or in the region of the pivot pin.

In a particularly preferred embodiment of the method, the starting material of step a. Pour liquid or mushy or semi-solid or semi-liquid or is a squeeze casting material or a semi-solid material.

The stated starting materials in this case have a temperature which corresponds approximately to the melting temperature. That means they are not overheated. Advantageous here is, inter alia, a reduced energy consumption during casting, since the starting material or the melt must be heated only to a relatively low temperature. In particular, for higher quantities of the cylinder tube is also advantageous that a reused mold due to the lower temperature has an increased life.

Preferably, the cylinder tube is made of the casting blank according to the invention or according to the method.

Particularly advantageously, the cylinder tube according to the invention is used in a hydraulic cylinder, which is operated as a lifting or traversing cylinder, especially when high displacement speeds of a piston are required. Depending on the direction of travel of the piston while a piston chamber or an annular space is subjected to pressure medium. For example, if the pressure medium channel, via which a connecting channel between the piston chamber and the annular space is formed, arranged in the rib or the directional control valve, via which a pressure medium connection of the piston chamber and the annular space is controlled, integrated in the cylinder tube bottom or attached to the cylinder tube bottom, eliminates a corresponding external line or piping of the piston chamber with the annulus or the two rooms with the directional control valve. The cylinder tube is particularly space-saving, spatially compact and stiff due to the saved piping. The stiffness has an advantageous effect on the adjustment of the hydraulic cylinder, since an attenuation of pressure pulses is the lower, the stiffer the cylinder tube is formed. The higher a degree of integration of the cylinder tube, d. H. the more sections for attaching or receiving hydraulic functional elements over the casting blank according to the invention are integrated into the later cylinder tube, the greater is this advantage. It is also advantageous that as the degree of integration increases, a number of potential leaks decrease.

Preferably, the cylinder tube is used in hydraulic cylinders with an operating pressure above 50 bar.

In the following, three embodiments of a cast blank according to the invention or cylinder tubes made therefrom are explained in more detail with reference to five figures. Show it:

1 in each case a schematic sectional contour of a cast blank and of a cylinder tube produced therefrom according to a first exemplary embodiment;

2 a lateral section of the cylinder tube 1 ;

3 a side section of a cylinder tube made of a second embodiment of a casting blank according to the invention;

4 a cross section of the cylinder tube 3 ; and

5 a side section of a cylinder tube made of a third embodiment of a casting blank according to the invention.

1 shows a schematic sectional contour S 'of a cast blank 1' and a schematic end contour S of a cylinder tube made therefrom 1 according to a first embodiment.

The sectional contour S 'of the cast blank 1' is according to the invention close to the final contour S of the cylinder tube 1 - ie "near net shape" - trained.

The cylinder tube 1 extends into 1 from left to right along a longitudinal axis 3 , In 1 left shows the cylinder tube 1 a first portion for receiving a hydraulic functional element. This section is referred to as a radially recessed recess 4 in the cylinder tube 1 formed with an internal thread (not shown). The hydraulic functional element which is to be received in this recess, a cover that is used in a later use of the cylinder tube 1 in a hydraulic cylinder is penetrated by a piston rod of the hydraulic cylinder. The end cover is via an external thread in the recess 4 screwed. According to the invention is in Gussrohling 1' while a corresponding recess 4 ' provided over a casting core near net shape, so that the recess 4 of the cylinder tube 1 can be produced with very little manufacturing effort together with the internal thread. The sectional contour S 'of the cast blank 1' can in the area of the recess 4 so close to the final contour S of the cylinder tube 1 be poured that only the internal thread is cut to the recess 4 to manufacture with internal thread.

The principle of the invention, a portion of the cylinder tube 1 near-net shape in the casting blank 1' provide in order to simplify subsequent manufacturing steps in this way, or to minimize an effort or to obtain a more compact or more stable cylinder tube is in the following other sections of the cylinder tube 1 implemented:
In the cylinder tube 1 is along the longitudinal axis 3 a piston chamber 8th educated. According to the invention is in Gussrohling 1' for this, about a corresponding Casting core, a piston chamber 8th' formed close to the final contour.

In 1 left is in the cylinder tube 1 a connection plate 6 for connecting a pressure medium line, a control block, a valve, a hydraulic block or a hydraulic plate (not shown) integrated. The connection plate 6 has a connection recess 10 and a passage recess 12 , which in turn according to the invention in the casting blank 1' via a corresponding casting core as a connection recess 10 ' and through-hole 12 ' are provided close to the final contour.

In 1 right is in the cylinder tube 1 in one piece a cylinder tube bottom 13 integrated. In the cylinder tube bottom 13 are also connections 14 and 16 , for example, a valve or other hydraulic control, as well as a groove 18 educated. According to the invention is the cylinder tube bottom 13 , the connections 14 and 16 , as well as the groove 18 already in the casting blank 1' via a corresponding casting mold and a cast core as a cylinder tube bottom 13 ' , Connections 14 ' . 16 ' and groove 18 ' provided near net shape.

For storage or for pivoting the cylinder tube 1 are radially on the outside of the cylinder tube 1 and diametrically two pivot pins 20 educated. According to the invention are also for these pivot pins 20 in the cast blank 1' about the appropriate design of the mold pivot pin 20 ' provided near net shape.

The final contour S of the cylinder tube 1 can in particular on the radial outside of the cylinder tube 1 with the sectional contour S 'of the cast blank 1' coincide, ie that the casting blank 1' possibly has unprocessed sections on its outside. In 1 necessary draft angles are not shown.

2 shows a lateral section of the cylinder tube 1 according to the first embodiment 1 , The cylinder tube 1 is from the casting blank 1' starting from the near-net shape sectional contour S 'in its final contour S made by machining processes (see. 1 ).

Deviating from the illustration according to 1 are in 2 to the cylinder tube 1 Hydraulic functional elements for control and for the operation of the hydraulic cylinder (not shown) attached or attached or connected. The functional elements are all in one area of the cylinder tube bottom 13 arranged.

A way valve 22 is at a planar and radial to the longitudinal axis 3 aligned outside 24 of the cylinder tube bottom 12 arranged. Furthermore, on an axial end face 26 of the cylinder tube bottom 13 several pressure medium connections 28 arranged. The piston chamber 8th and the pressure fluid connections 28 are via the directional valve 22 and over in the cylinder tube bottom 13 trained pressure medium channels (not dargstellt) connectable.

The 3 and 4 show a manufactured from a second embodiment of a casting blank according to the invention cylinder tube 101 , 3 represents the cylinder tube 101 in a lateral section, 4 on the other hand shows a cross section of the cylinder tube 101 out 3 ,

According to 3 has the cylinder tube 101 different from the first embodiment according to the 1 and 2 a rib 140 in which a pressure medium channel 142 is designed as a connecting channel. The pressure medium channel 142 on the one hand flows into 3 right in a front side 126 one according to the invention in one piece into the cylinder tube 101 integrated cylinder tube bottom 113 and on the other hand in 3 left in an annulus 109 of a cylinder tube end cap (not shown) of an outer surface of a piston rod, an end face of a piston 107 and an inner surface of the cylinder tube 101 is limited. The annulus 109 is about the piston 107 from a piston chamber 108 separated. In the piston chamber 108 flows into 3 on the right another pressure medium channel 143 , which is approximately axial in the cylinder tube bottom 113 is trained. The pressure medium channel 143 flows into 3 right in the front 126 of the cylinder tube bottom 113 ,

The pressure medium channels 142 and 143 each with a connection of a directional control valve 144 connected. Via the directional control valve 144 can depending on the switching position of the annulus 109 with the piston chamber 108 can be brought into pressure medium connection or the pressure medium connection between the two rooms can be interrupted.

A displacement of the piston 107 in the cylinder tube 101 via a (not dargstellte) hydraulic pump. About the hydraulic pump and a (also not shown) directional valve is either the annulus 109 or the piston chamber 108 acted upon by pressure medium. The pressure medium is thereby from the hydraulic pump in a closed circuit depending on the switching position of the directional valve either in the annulus 109 or in the piston chamber 108 promoted.

Is via the hydraulic pump, for example, pressure medium in the piston chamber 108 promoted, this results in a bottom of the piston 107 and in 3 left-directed force. So that the piston 107 can move to the left, the directional control valve 144 be open so that over the Druckmittekanäle 142 and 143 Pressure medium from annulus 109 in the piston chamber 108 can flow. The same applies to a movement of the piston 107 in 3 left to right.

If, on the other hand, the piston is to be locked in its position, the directional control valve is brought into the closed position, so that no more pressure medium from the annular space 109 in the piston chamber 108 , and vice versa, can flow.

4 shows the cross section of the cylinder tube 101 according to the section line AA in 3 , The cylinder tube 101 has a substantially circular cylindrical cross-section. It points in 4 above the invention integrally formed rib 140 on, in which the pressure medium channel 142 is trained. The rib 140 , the pressure medium channel 142 and the pressure medium channel 143 (see. 3 ) are according to the invention already in a casting blank of the cylinder tube 101 had been provided near the final contour.

5 shows a side section of a cylinder tube made of a third embodiment of a casting blank according to the invention 201 ,

Notwithstanding the in the 1 to 4 illustrated two embodiments, the third embodiment according to 5 additionally a displacement measuring unit 250 on.

The cylinder tube 201 is integral with a cylinder tube bottom 213 formed according to the invention already close to final contour in a casting blank of the cylinder tube 201 has been formed. In the cylinder tube 201 is a piston 207 along the longitudinal axis 3 arranged axially displaceable, in 5 left one of a cylinder tube end cover (not shown), a piston rod, an end face of the piston 207 and an inner surface of the cylinder tube 201 limited annulus 209 is trained. This one is about the piston 207 from a piston chamber 208 separated.

In 5 top right is in the cylinder tube 201 a pressure medium connection 256 formed over which this piston chamber 208 can be acted upon with pressure medium, so that a displacement of the piston 207 in 5 can be done to the left. Also the pressure medium connection 256 is according to the invention already close to the final contour in the casting blank of the cylinder tube 201 been formed.

The path measuring unit has a displacement sensor 252 , a sensor rod 264 and a transmitter formed by a magnet 254 , The displacement sensor 252 the path measuring unit 250 is over a hanger 258 and a variety of screws 260 in tapped holes 262 are screwed in, on the cylinder tube bottom 213 attached. The cylinder tube bottom 213 is in the area of a hole 266 coaxial to the longitudinal axis 3 from the sensor rod 264 passed through, with the sensor rod 264 in the hole 266 pressure medium tight against the cylinder tube bottom 213 is sealed.

As a guideline is the Weggeber 254 in a radially stepped back groove 268 the piston rod of the piston 208 edged. Between the piston rod and the sensor rod 264 is a small radial annular gap 270 designed so that the piston 207 collision-free in the cylinder tube 201 is displaceable and no contact between the piston rod and the sensor rod 264 is possible.

Will the piston 207 moves, the magnet moves 268 accordingly with. The movement relative to the stationary sensor rod 264 is doing from the displacement sensor 252 detected.

Disclosed is a casting blank for a cylinder tube of a hydraulic cylinder having portions close to the final contours, i. H. are formed close to a final contour of the cylinder tube. At or in the finished in their final contour sections of the cylinder tube hydraulic functional elements are to be set or record. Furthermore, a manufacturing method is disclosed, via which a casting blank according to the invention can be produced and via which a cylinder tube can be manufactured from the casting blank. Furthermore, a cylinder tube is disclosed, which is made of a cast blank according to the invention or via the method.

LIST OF REFERENCE NUMBERS

S '

Cut contour cast blank

S

Final contour of the cylinder tube

1'

cast blank

1; 101; 201

cylinder tube

3

longitudinal axis

4 ', 4

recess

6 ', 6

connecting plate

107; 207

piston

8 ', 8; 108

piston chamber

109

annulus

10 ', 10

connection recess

12 ', 12

Durchgangausnehmung

13 ', 13; 113; 213

Cylinder tube sheet

14 ', 14

connection

16 ', 16

connection

18 ', 18

groove

20 ', 20

pivot pin

22

way valve

24

outside

26; 126

front

28

Pressure medium connection

140

rib

142

Pressure fluid channel

143

Pressure fluid channel

144

way valve

250

displacement measuring

252

displacement sensor

254

encoder

256

Pressure medium connection

258

hanger

260

screw

262

threaded hole

264

sensor rod

266

drilling

268

groove

270

annular gap

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3835383 A1 [0007]

Claims (12)

Cast blank for a cylinder tube ( 1 ; 101 ; 201 ) of a hydraulic cylinder, on the outer circumference of a bearing means for fastening, supporting or supporting the hydraulic cylinder is provided, characterized by a near-net shape integrally formed with the casting blank section for applying or for receiving a hydraulic functional element. Cast blank according to claim 1, wherein the section comprises a connection ( 14 ' . 16 ' ) or a connection surface or a connection recess ( 10 ' ) or a passage recess ( 12 ' ) or a connecting pin or a connecting flange or a connecting plate ( 6 ' ) or a hydraulic control block or a or a valve housing or a cylinder tube bottom ( 13 ' ) or a rib or a threaded area ( 4 ' ). Cast blank according to claim 1, wherein the hydraulic functional element is a hydraulic line or a pressure medium channel ( 142 . 143 ) or a pressure medium container or a hydraulic control block or a valve or a pressure relief valve or a directional control valve ( 144 ) or a lowering brake valve or a pressure measuring unit or a hydraulic pump or an electric motor or a displacement sensor ( 252 ) or Weggeber ( 254 ) a path measuring unit ( 250 ) or a cover is. Cast blank according to claim 1, wherein the bearing device comprises a pivot pin ( 20 ) having. Cast blank according to claim 1 made of cast steel or nodular cast iron. Method for producing the cylinder tube ( 1 ; 101 ; 201 ) over the casting blank ( 1' ) according to one of the preceding claims, comprising the steps of: a. Pouring the cast blank ( 1' ); b. Finishing the cylinder tube ( 1 ; 101 ; 201 ); the section at step a. Casting is formed over a near-net shape formed mold. The method of claim 6, wherein the portion is formed over a near net shape formed casting core. Method according to claim 6, wherein prior to step a. Pouring a feeder of the casting mold is arranged in the area of a material aggregate or in the area of the section. A method according to claim 6, wherein a starting material of step a. Casting is liquid or pulpy or semi-solid or semi-liquid, or is a squeeze-casting material or semi-solid material. Cylinder tube ( 1 ; 101 ; 201 ) for a hydraulic cylinder, wherein the cylinder tube ( 1 ; 101 ; 201 ) is produced according to the method according to one of the claims 6 to 9, or wherein the cylinder tube ( 1 ; 101 ; 201 ) from a casting blank ( 1' ) is manufactured according to one of the claims 1 to 5. Cylinder tube ( 1 ; 101 ; 201 ) according to claim 10, wherein the hydraulic cylinder is a lifting or Verfahrzylinder. Cylinder tube ( 1 ; 101 ; 201 ) according to claim 10 or 11 for an operating pressure greater than 50 bar.

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