JPH06504514A - Multi-stage telescopic jib - Google Patents

Abstract

A multistage telescope jib, in particular for a loading crane on a truck, has hydraulic units composed each of a piston and a cylinder arranged between the successive, telescopically nested arms (11-14). A pipe (23a-c) projects axially from the bottom of the cylinder into the chamber of the cylinder, sealingly extending into the hollow piston rod (17a-c) when the piston is retracted and sealing the chamber of the cylinder from the inner chamber of the hollow piston rod. In order to ensure an automatic extension sequence of the telescope arms, the inner chamber (25a-c) of each hollow piston rod (17a-c) is linked to the cylinder chamber (24b-d) of the next-outer hydraulic unit (15b-d) by a preferably rigid line (19a-c) and the inner chamber (25a-c) of each hollow piston rod (17a-c) communicates with the cylinder chamber (24a-c) of the same hydraulic unit (15a-c) when the piston (18a-c) is fully extended.

Description

[Detailed description of the invention] Multi-stage telescopic jib Technical field The present invention provides an arrangement between a plurality of arms disposed in and out of each other in a continuous nested manner. a hydraulic unit with a piston and a cylinder is arranged in each In this case, in the cylinder of the innermost arm, at least the bottom of the cylinder The limb canal stands up in the cylinder chamber in the axial direction, and the piston is at least partially The hollow piston rod is sealed against this piston when pushed in. The brackets allow the cylinder chamber to be opened into the hollow piston rod. Cranes, especially for loading and unloading vehicles, which are sealed against the interior of the vehicle. This invention relates to a multi-stage telescoping jib for.

Background technology Sequence control for cargo handling cranes is mostly based on fixed arms of telescoping jibs. ensure that they are pushed or pushed in a fixed and prescribed order. It has the purpose of proving. By Palfinger Co., Ltd. The cargo handling cranes used in the However, if the telescoping jib is equipped with Only the arms that are directly supported by the surrounding bending arms are forced to extend first. It has shortcomings.

The remaining arm of the telescopic jib (extrusion arm), on the other hand, The order has not been determined.

Palfinger Corporation's openly used crane has a bending arm placed on it a bending arm of the hydraulic unit which operates the first arm by means of a stop that is A valve is provided which is operated at the end of the piston towards the piston. This first a Only when the arm is fully extended does the valve configured as a check valve Releases the flow of hydraulic fluid into the cylinder of the telescoping arm.

German Published Application No. 3413443 already describes an arbitrary extrusion order. It shows a three-stage telescoping jib with a control system for determining the position. center The hydraulic oil supply to the cylinders is via a telescoping slide fixed to the basic cylinder. This sliding conduit is technically uneconomical and the basic cylinder It takes up some space near the side of the piston rod. into the outermost cylinder The hydraulic oil supply is via a tube projecting axially from the bottom of the cylinder; A hollow piston, the tube of which is sealed against the piston and combined with a control device. reaches inside the rod. The oil flowing out of said tube of the basic cylinder is routed through a conduit. into another tube that protrudes from the bottom of the central cylinder, and this tube inside the hollow piston rod of this piston. is familiar with The end of this hollow piston rod is the outermost hydraulic unit It communicates with the cylinder chamber of. Control of the extrusion order is described in the German Federal Republic of Application No. In the specification of 3413443, arbitrary extrusion order can be controlled. This is done only via an external control device. For this reason, the telescoping arm is the innermost is not guaranteed to be automatically pushed out starting from the arm of Further According to the specification of Federal Republic of Italy Application No. 3413443, there are more than three-stage type. How many hydraulic units can be used in a stage telescopic jib than three hydraulic units? There is no theory that this is possible.

Disclosure of invention The object of the invention is to create a structurally simple and compact device of the general form at the outset. Configured to aid in automatic sequencing of multiple telescoping arms be.

According to the invention, this means that the inner chamber of each hollow piston rod is advantageously Connected with the cylinder chamber of the next outer cylinder unit via a rigid conduit In addition, the inner chamber of each hollow piston rod is When removed, it communicates with the cylinder chamber of the same cylinder unit. This is achieved by

The pipe that protrudes from the bottom of the cylinder and reaches into the hollow piston rod is the next (third pipe). ) Hydraulic oil to hydraulic units – used only for supply and therefore each At each piston position, it always communicates only with the inner chamber of the hollow piston rod. Regarding the specification of the Federal Republic of Germany Application No. 3413443, which is The tube of the hydraulic unit according to the invention, together with the position of the piston, is connected to the next outer hydraulic Configured to allow control functions for the supply of hydraulic oil into the unit. Ru. The piston or the cylinder of the hydraulic unit (also partially pushed in) of a hollow piston rod whose chamber is connected to the cylinder chamber of the next hydraulic unit. If the piston is completely pushed out whereas it is sealed against the inner chamber In this case, the inner chamber of the hollow piston rod does not communicate with the cylinder chamber of the same hydraulic unit. Ru. Therefore, when supplying hydraulic fluid into the cylinder chamber of a hydraulic unit, the hydraulic The piston is first pushed without the oil flowing further into the next outer hydraulic unit. can be guaranteed to be released. when the piston is fully pushed out For the first time, there is communication between the cylinder chamber and the inner chamber of the hollow piston rod, and The pressure oil can flow further into the next outer hydraulic unit.

Hydraulic oil dependent on the piston position in the next outer cylinder – related to the supply The above-mentioned control action of the tube can be carried out in a simple form, for example if the tube is If the piston is pushed out completely by this, , exiting from this piston or a sealing member disposed within it. This can be achieved by at the free end of the piston or tube Due to the corresponding sloping surface, the tube actually becomes a hollow piston when the piston is pushed in again. Can penetrate into stone rods. piston when the piston is pushed In order to eliminate problems with reintroduction of the tube into the tube, in an advantageous embodiment remains guided within the piston even when the piston is fully pushed out. at least two openings in the circumferential wall near the free end of the pipe, the openings The cylinder is located within the cylinder chamber when fully extruded, and this Communication between the cylinder chamber and the hollow piston rod through the end region of the tube by is starting to form. When the piston is in the pushed position, it is closed. A tube wall seals the interior of the hollow piston rod to the cylinder chamber. but , when the piston is fully pushed out, the hydraulic oil is near the free end of the tube. into the tube through the hole provided in the hole, and from there into the inner chamber of the hollow piston rod. , and finally into the cylinder chamber of the next outer hydraulic unit.

A conduit is actually installed for further flow of hydraulic oil to the next outer hydraulic unit. All hydraulic units are nearly identical except for the outermost hydraulic unit that is not configured and hydraulically connected in series. Series of hydraulic units In order to obtain the desired actuation, the innermost Only the cylinder chamber of the hydraulic unit is loaded with hydraulic oil. extrusion When one of the telescopic jibs is operated by the self-side 1 of the hydraulic unit, An arm can only be pushed out if the next inner arm is already pushed out. is guaranteed.

The piston rod of the hydraulic unit and the same arm of the telescopic jib are located next to each other. Since the cylinder of the hydraulic unit on the side is fixedly connected, the hollow piston rod is The conduit leading from the inner chamber of the pad into the next outer hydraulic unit is advantageously wear-resistant. It can be configured as a flexible and pressure-tight rigid conduit.

In order to press the arms of the telescopic jib in an orderly manner, all pistons must be Supplying hydraulic oil into the annular chamber defined between the cylinder rod and the cylinder wall It can also be loaded in the pushing direction by. First, the hydraulic pressure from the cylinder chamber A predetermined push order is achieved by successively opening valves that prevent oil from flowing out. It is possible to achieve the order. Such a [drain valve] is connected to the next outer hydraulic unit. It can be controlled by the push-in state of the cut. According to an advantageous embodiment, the control The valve is advantageously mounted next to the hollow piston rod of the inner hydraulic unit. It can also be a check valve that can be opened in the locked direction in the conduit leading to the cylinder chamber. can. Hydraulic oil supply with such a check valve to push out the piston is always possible. When the piston is loaded in the pushing direction, this check valve is is shut off, but the next outer piston has already been pushed out via the control conduit. When the check valve receives a signal indicating that Pressure oil is transferred from the cylinder chamber via a conduit to the hollow piston rod of the next inner cylinder. It can be flowed into the head. From here, the hydraulic oil flows through the pipe according to the invention. and flows from this tube into the outflow conduit. This outflow conduit connects the inner hydraulic unit to It further opens into a conduit leading to the inner chamber of the hollow piston rod of the Hydraulic oil can again flow out via the pipe.

In summary, the tube according to the invention can be used to automatically control the extrusion sequence frequency. In addition to being used as a return conduit for hydraulic oil when pushing a hydraulic unit, It is also used.

Brief description of the drawing Further advantages and details of the invention are explained in more detail with the aid of the following drawings.

Figure 1 shows a schematic diagram of a cargo handling crane with a four-stage telescoping jib (push arm). 2 shows a sequence control according to the present invention comprising a hydraulic control device for the push order. FIG. 3 shows the wiring diagram of the control according to the present invention having an electric control device of the push order. The sequence control wiring diagram is shown, and Figure 4 shows the bottom of the cylinder when the piston is pushed in. Fig. 5 shows an axial cross-section of the hydraulic unit in the region where the piston is fully pushed. FIG. 4 shows an axial section in the region of the piston when it is drawn out;

BEST MODE FOR CARRYING OUT THE INVENTION The cargo handling crane shown in FIG. 1 and corresponding to the prior art is The horn has a support 3 which is rotatable about a vertical axis at the base 8. child A lifting arm 5 connects the horizontal axis to the column 3 via the lifting cylinder 1. It is pivotably supported at the center. Centered on another horizontal axis 9, the so-called bending The arm 7 is pivotable by means of a hydraulic unit 6 and a toggle lever 2. Bending a The arm 7 has a series of pre-arranged entire push arms placed therein, shown as a push arm. The arms 11-14 form a four-stage telescopic jib.

The invention provides a sequence for extending and retracting arms ll, 12.12.14. Regarding the control, the arm is connected to the bending arm 7 or - 4 hydraulic units! , 5a-d (some of which are not visible). are combined.

FIG. 2 shows hydraulic units 15a-d for a multi-stage telescoping jib according to the invention. The wiring diagram is shown below. Each hydraulic unit is slidable within the cylinders 16a-d. It has pistons 18a-d which are mounted on the piston rods 17a-d and have piston rods 17a-d. are doing. The cylinder 16a can be coupled with the bending arm 7 of FIG. 1, for example. On the other hand, the piston rod 17a is connected to the arm 11, and the piston rod 17b is connected to the arm 11. The arm 12 and the piston rod 17c are connected to the arm 13, and the piston rod 17d is connected to the arm 13. can be combined with the frame 14. of the three outer hydraulic units 15b-d. The cylinders 16b-d are respectively pistons of the next inner hydraulic unit 15a-c. are fixedly connected to the connecting rods 17a-c and will therefore be described in further detail. The conduits 19a-c, 20a-c can also advantageously be configured as rigid conduits. Wear. The outlet conduit 21 and the inlet conduit 22 can also be configured as rigid conduits. Wear.

One tube 23 from each of the cylinder bottoms of the three inner hydraulic units 15a-c a-c stand up in the cylinder chamber in the axial direction, and the pistons 18b and 18 c sealed against these and hollow when at least partially pushed in It reaches inside the piston rod, thereby making the cylinder chambers 24b and 24c hollow. The inner chambers 25b, c of the piston rods 17b, c are sealed.

The sealing element applied to the outside of the tube in the area of the piston is shown in FIG. Although not shown, it is clear in FIGS. 4 and 5.

Now, in contrast to the prior art, the tubes 23a-c according to the invention are connected to the piston (innermost If the piston 18a) of the hydraulic unit 15a is fully pushed out, the Each cylinder as shown in the innermost hydraulic unit 15a The chamber is configured to allow communication between the chamber and the inner chamber of the piston rod of the same hydraulic unit. It is.

Here, the tube 23a is designed to be shorter than the travel distance of the piston 1.8a.

For this reason, if the tube is completely pushed out from the piston 18a, this piston or from a sealing member disposed therein, thereby providing an outlet. Hydraulic oil supplied via the conduit 21 is supplied to the piston rod from the cylinder chamber 24a. It is possible to reach into the interior chamber 25a of 17a. According to the present invention, this inner chamber 2 5a for example via a rigid conduit 19 to the series of the next outer hydraulic unit 15b. It is connected to the download chamber 24b. This ensures that the outlet conduit 21 is under pressure. When the piston 18a is loaded with hydraulic oil, the piston 18a is The head 17a is pushed out together with the innermost arm of the jib. piston 1 Only when 8a reaches the end position shown in FIG. It flows into the cylinder 15b, where it aligns the piston 18b with the piston rod 17b. move outward together. In FIG. 2, the piston 18b has already been partially pushed out. However, both outer hydraulic units 15C and d are still fully pushed in. It is rare.

Overall, in a practically identical configuration of hydraulic units 1.5 a-c, additional Automatic sequence control is obtained without any external control device, and this sequence control Now, only if the next inner piston rod is already fully pushed out, The next outer piston rod is implemented.

Due to the pushing movement of the piston rods 17a-d, the bodies are always in communication with each other. - Hydraulic conduits 22.20a-c are provided. Each of these conduits has a piston In the annular chamber defined between the tongue rods 17a-d and the cylinder wall, The exposed pistons 1.8a-d are open on the side opposite to the piston rod. . In this case, from this annular chamber, piston rods 17a-C are passed in the region of the piston. one each guided by and separated from the inner chambers 25a-C of the piston rod. Conduits 26a-c are provided which connect to the next outer hydraulic unit. - opening into hydraulic conduits 20a-c.

In this manner, the hydraulic-artificial conduit 22 is negative by hydraulic oil under pressure. During loading, all pistons 18a-d are first loaded in the pushing direction. this Subsequently, the piston 18a has only the smallest section, and the tube 23a is connected to the cylinder chamber 24a. can be pushed in until it seals. On the other hand, the reverse valve 27a first Further pushing of the piston 18a is blocked. Pistons 18b and 18c , first, the pipe 23b or 23c seals the cylinder chamber 24b or 24c. You can also push it in a little bit until it clicks. The first closed check valve 27b or 27c, hydraulic oil also flows to and from cylinder chambers 24b and 24c. First, the pistons 18b and 18c cannot be pushed any further. Only the outermost piston +8d has hydraulic oil flowing out from the cylinder chamber 24d. Since it does not get in the way, it can be pushed freely from the beginning. hydraulic oil This kind of outflow of the rod first occurs through the conduit 19C, the piston rod inner chamber 25c, and This takes place via a pipe 23C to which an outflow conduit 28c is connected. In this outflow conduit A second check valve 29c is disposed, and the outflow conduit 28c is connected to the first check valve 29c. 27c opens into conduit 19b on the side opposite the cylinder chamber. Second check valve 29 c indicates that hydraulic oil enters the pipe 23c when the piston 18c is pushed out. prevent, but allow unhindered outflow of hydraulic oil from this pipe 23e. conduit Outflow from 19b through hydraulic units 15b and 15a takes place in a similar manner. Ru.

After the outermost piston rod 1.7 d is completely pushed in, the piston 18 d is generally enough to detect the fully pushed-in position of the piston 18d. The first shutoff placed in the control conduit 30c via the operating bin 31d, which is the device The checked valve 32d is opened. Now, via control conduit 30c, the hydraulic oil is It flows to the next inner hydraulic cylinder 15c and opens the check valve 27c there. child Therefore, the hydraulic oil existing in the cylinder chamber 24c can flow out by the method described above. , and the piston 18C can be pushed together with the piston rod 17C. . In this case, the fully pushed-in piston 18d is inverted through the operating bin 31c. Valve 32c is pressed, which causes hydraulic oil to flow through control conduit 30b. It flows to the pressure type unit 15b. Here, the same control as in the case of the hydraulic unit 15c is applied. A divine action occurs. Finally, the hydraulic oil reaches into the conduit 30a and the first check valve 2 7a, and the innermost piston rod 17a is also pushed in. can be done.

A device for detecting the fully pushed-in position of the piston is connected to the corresponding position of the telescopic jib. It is also possible to detect the position of the arm moved by the piston rod. is clear. Depending on the position of the telescoping arm, this arm may not be fully pushed in. As soon as a control pulse is induced.

The embodiment shown in FIG. 3 differs from the embodiment shown in FIG. 2 mainly in controlling the pushing order. The difference is caused by the fact that the first check valves 27'a-C for Become.

Otherwise, the hydraulic unit is configured substantially the same as in the embodiment shown in FIG. has been done. Although tubes 23a-c are shown only as lines in FIG. Of course, it is hollow like the tube shown in FIGS. 2 or 4 and 5.

Hydraulic conduit 22 applies pressure to force the piston rod and thus the arm of the jib. Can be applied. This first causes the piston of the outermost hydraulic unit 1.5d to Stone is pushed in. Corresponding in the corresponding arm of the piston rod or jib When the piston is fully pushed in, the stopper 31d of the switching member 32'd is closed, whereby the current supplied from the power source 33 via the electric wire 34 is can flow into conductor 300' which passes through electrically openable check valve 270'. Ru. Therefore, when the piston of the outermost hydraulic unit is fully pushed in, Valve 27'c opens, thereby removing air from the cylinder chamber of hydraulic unit 15c. Release the hydraulic oil outflow and push this hydraulic unit over it. It's similar Then, the stopper 31'c and the switching member 32'C are connected to the electromagnetic operation via the conductor 30'b. The check valve 27'b can be operated by the switching member 32'b, and the stopper 31'b is to switch the electromagnetically operable check valve 27'a via the electrical control lead 30'a. . Therefore, the overall pressing order is automatically determined.

Instead of mechanically operated switching members 32' b-d, contactless switching is possible. switching elements, such as electromagnetically operated reed switches or optoelectronic devices or similar It is also possible to provide a switching member which is switched over.

FIG. 4 shows the series when the piston 18a is completely pushed into the hydraulic unit 15b. FIG. 3 shows a longitudinal sectional view taken in the region of the bottom 34b. Hollow from the cylinder bottom 34b The pipe 23b, which is screwed together via the same 35, stands up in the cylinder chamber in the axial direction. . Check valve 27b prevents hydraulic oil from flowing from pipe 23b into a conduit connected to point 36. allow the unchecked outflow of Hydraulic oil supply to push piston +8b is carried out through an opening 37 and a conduit section 38 shown in dashed lines, which conduit section , a check valve (not shown in detail at point 39) (first check valve 27b in FIG. 2 or is supplied with hydraulic oil via a check valve 27'b (corresponding to check valve 27'b in FIG. 3). tube 23b is sealed from the piston 18b via the seal member 40, so First, the hydraulic oil does not reach the interior chamber 25b of the hollow piston rod 17b. When hydraulic oil is supplied through the opening 37, the piston is pushed out. .

Piston 18b reaches the fully extended position shown in FIG. When the hydraulic oil comes into contact with the chain member 52), the hydraulic oil flows from the cylinder chamber 24b to the pipe 23. A hollow piston is inserted through a hole 41 in the wall of this tube near the free end of b. It reaches inside the inner chamber 25b of the rod 17b. In this case this oil is from, as shown This flows into the cylinder chamber of the next outer hydraulic unit via conduit 19b, which is not A hydraulic unit can be pushed out.

In order to force the piston 18b, a hydraulic oil is supplied via a conduit and opening 42 (not shown). The oil is supplied into an annular chamber provided between the piston rod 17b and the cylinder surface. It will be done.

This causes the piston 18b to initially The bore 41 is moved slightly inwardly until it is closed by the piston 18b. wife Until there, the hydraulic fluid flows from the cylinder chamber 24b and the opening 41 through the pipe 23b. can be released. After this short movement of piston +8b, now cylinder chamber 2 4b or sealed against the inner chamber of pipe 23b and for the time being hydraulic oil is not flowing. Since it cannot be removed, this piston remains as it is. Now installed at location 39 Check valve that is closed or opens after the next outer hydraulic unit is fully pushed in. and the hydraulic oil can flow out of the cylinder chamber 24b via the conduit 38; Piston 18b then moves to the position shown in FIG. Therefore, piston +8b or push the operating pin 31b to the right against the action of the spring 43, thereby tightening the screw 4. The check valve 32b installed in the hole closed by 4 is opened. this As a result, the hydraulic oil flows into the chamber 46 against the original locking direction of the check valve 32b. (not shown, but corresponds to control conduit 30b in FIG. 2) connected to and a control conduit connected to the chamber 45 (not shown, but comparable to the control conduit 30a in FIG. 2). corresponding) and this causes the first inverse of the next inner hydraulic unit to The stop valve can be opened, which allows the hydraulic unit to be pushed in. Ru.

In the embodiment shown in FIGS. 4 and 5, the piston rod 17b is configured as a double tube. an inner tube 48, in this case located concentrically with respect to the outer tube 47; surrounds the inner chamber 25b of the piston rod 17b. The outer pipe 47 and the inner An annular chamber 49 located between the conduit 48 and the conduit (corresponding to conduit 26b in FIG. 2) and the conduit pipes hydraulic oil from the cylinder interior 50 through the opening 51. Stone rod - guided from the piston rod through the annular chamber 49 and from there to the next the piston rod to guide it into the cylinder annular chamber of the hydraulic unit outside the It is hydraulically partitioned from the inner chamber 25b in the door.

Of course, the invention is not limited to the illustrated embodiment. For example, the four hydraulic units shown A different number of hydraulic units can also be connected to each other.

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Claims (13)

[Claims] 1. It is placed between multiple arms placed inside and outside each other in a nested manner. Hydraulic units each having a piston and a cylinder are arranged, In this case, at least in the cylinder of the innermost arm, the tube is removed from the bottom of the cylinder. The tube extends axially into the cylinder chamber, the tube being at least partially connected to the piston. Inside the hollow piston rod that is sealed against this piston when pushed in , and this makes the cylinder chamber the inner chamber of the hollow piston rod. Particularly for cargo handling cranes of cargo transport vehicles, of the type sealed against In the multi-stage telescopic zip, each of the hollow piston rods (17a -c) the inner chamber (25a-c) of the Connected to the cylinder chamber (24b-d) of the side cylinder unit (15b-d) In addition, each hollow piston rod (17a-c) has an inner chamber (25a-c). c) is the same cylinder unit when the pistons (18a-c) are fully pushed out. It communicates with the cylinder chamber (24a-c) of the knit (15a-c). A multi-stage telescopic zip that is characterized by: 2. The tubes (23a-c) are shorter than the travel distance of the pistons (18a-c). and thereby when the pistons (18a-c) are fully pushed out. , exiting from this piston or a sealing member disposed within it. The telescoping zip according to claim 1, characterized in that: 3. tubes (23a-c) when pistons (18a-c) are fully pushed out; is also guided within the piston and has at least one in the circumferential wall near its free end. The pistons (18a-c) are fully depressed. located within the cylinder chamber (24a-c) when ejected, and Through the end region of the tube (23a-c) there is thus a connection between the cylinder chamber (24a-c) and the hollow communication with the piston rods (18a-c) is formed; The telescoping zip according to claim 1, characterized by: 4. All hydraulic units (15a-c) except the outermost hydraulic unit According to any one of claims 1 to 3, the structure is configured to have the same shape. Telescopic zip. 5. guided into the cylinder chamber (24a-c) and therein the area of the cylinder bottom. A first check valve (27a-c; 2 Any one of claims 1 to 4, characterized in that 7'a-c) are arranged. 1. The telescopic zip described in 1. 6. Each hydraulic unit except the innermost hydraulic unit (15a) (15b-d) or of a telescoping jib coupled to said hydraulic unit. One hydraulic unit of the arm is coupled to or to the piston (18b-d). A device for detecting the fully pushed-in position of the arm (31b-d, 32b -d; 32'b-d, 32'b-d), and this device has a piston (18b-c) or in the fully pushed-in position of the arm connected thereto. Open the valves (27a-c, 27'a-c) via the control conduits (30d-c) and In the released state, hydraulic oil passes through this valve to the next inner hydraulic unit (15a-c). The cylinder chambers (24b-d) of the A telescoping zip according to any one of claims 1 to 5. 7. The first check valve (27a-c, 27'a-c) can be opened even in the locking direction. , and the check valve is a valve openable via the control conduit (30a-c; 30'a-c). The telescoping zip according to claim 5 or 6, characterized in that it is formed. 8. The pistons (18b-d) or the arms connected thereto are fully pushed in. The device for detecting the position is mechanically operated by the piston or a member connected thereto. hydraulically operated control valves (32b-d), the control valves being Hydraulic oil is routed through hydraulic control conduits (30a-c) to the next inner hydraulic through hydraulically openable valves (27a-c) of the unit (15a-c); Claim characterized in that these valves (27a-c) are adapted to open. 7. The telescoping jib according to 6 or 7. 9. The pistons (18b-d) or the arms connected thereto are fully pushed in. The device for detecting the position is mechanically operated by the piston or a member connected thereto. electrical switching member (32'b- d), and the switching member is connected via an electrical control conduit (30'a-c). electromagnetically openable valves (27'a) of the next inner hydraulic units (15a-c). -c) The telescoping zipper according to claim 6 or 7, characterized in that: -c) is controlled. 10. An outflow conduit (28a-) is connected to the end of each tube (23a-) on the bottom side of the cylinder. c) is connected. Telescopic zip. 11. The outflow conduits (28a-c) are provided with a second check valve (29 a-c) are arranged and the outflow conduit (28a-c) is connected to the first check valve (28a-c). 7a-c) opening into the conduit on the side opposite the cylinder chamber (24a-c). The telescoping zip according to claim 5 or 10, characterized in that: 12. On the side of the extruded piston (18a-d) opposite the piston bottom, a rigid Sexual inlet-hydraulic conduits (22, 19a-c) connect with piston rods (17a-c) It opens into the annular chamber defined between the cylinder wall and the outermost fluid pressure From this annular chamber, the pistons are removed from the area of the pistons (18a-c), excluding the formula unit. The inside of the piston rod (17a-c) is guided through the piston rod (17a-c). Conduits (26a-c) separated by chambers (25a-c) are connected to the external hydraulic Inlet to unit (15b-d) - open to hydraulic conduit (19a-c) The telescoping zip according to any one of claims 1 to 11, characterized in that: 13. The piston rods (17a-c) are configured as double tubes and are further An inner tube (48) arranged concentrically with respect to the side tube (47) is a piston rod. (17a-c) surrounding the inner chamber (25a-c) and the outer tube (47) and the inner tube (48), the annular chamber (49) forming a conduit. 13. The telescoping zip according to claim 12.