RU2219385C2 - Hydraulic cylinder - Google Patents

Abstract

FIELD: mechanical engineering. SUBSTANCE: invention relates to lifting and transportation machinery, namely, to double-acting hydraulic cylinders designed for lifting and lowering support and mounting feet of outriggers of crane-and-manipulator plants. Proposed hydraulic cylinder contains housing with welded-to bottom, detachable through cover and end connector for fastening on end of extensible beam of slewing gear of crane-and-manipulator plant, one sided hollow rod with piston and end connector for butt-joining of foot with selfaligning support bearing plate, supporting and sealing members of movable and fixed joints, mud scraper and channels to feed working liquid provided with threaded connecting unions. Threaded unions for delivery of working liquid into piston and rod spaces of hydraulic cylinder are spaced in circumference. Bosses with threaded holes designed for fastening mounted one-sided pilot-controlled check valve are welded on side wall of housing sleeve. EFFECT: simplified design, decreased overall dimensions, improved reliability in operation and facilitated assembling and disassembling of hydraulic cylinder. 5 cl, 10 dwg

Description

 The invention relates to the field of hoisting and transport engineering, and in particular to double-acting hydraulic cylinders for lowering and lifting the supporting and mounting paws of the remote outriggers of crane manipulators.

 A fairly large number of analogues of the invention are known both in domestic and foreign development (see, for example, author certificate. SU 889986, F 16 J 10/02, 1981; SU 1599252, B 60 S 9/02, 15.10.90 g .; applications of Germany 4002558, F 15 B 15/14, 08/23/90; GB 1465289, B 60 S 9/10, 2.03.77; GB 2058693, B 60 S 9/00, B 60 F 1 / 00, B 60 D 15/02, 04/15/81; JP 58-50898, B 60 S 9/12, 11/12/83; Pat. US 4,236,643, F 15 B 15/00, 05/10/2000 g .; US 544968, F 01 B 31/00, 08/15/95; RU 2148733, F 15 B 15/00, May 10, 2000; V. A. Vasilchenko. Hydraulic equipment of mobile machines. Reference book. M: Engineering, 1983, BBK 34.447, V19, UDC 62-82 / 625.08 (03), p. 93, Fig. 340, and other general technical literature on hydraulic drives).

 In its most general form, the remote outrigger is a power telescopic rack with a support-mounting pivot that is articulated or rigidly fixed at the end of the beam of the support-rotary device of the crane manipulator, which can be pulled out in the transverse direction, which can be pressed to the ground and secured to him.

 In a number of well-known remote outriggers (JP 58-50898, US 4236643, etc.), the supporting and mounting legs are moved using kinematically connected autonomous double-acting hydraulic cylinders. At the same time, spatially indicated hydraulic cylinders can be placed both outside and inside telescopic racks.

 This design of outriggers simplifies the design of the drive hydraulic cylinders and allows you to use the corresponding standardized and mass-produced drive to move the support legs.

 However, in this case, the design of remote outriggers as a whole is much more complicated, their dimensions increase and weight perfection worsens.

 In others, the design of the hydraulic cylinder itself, oriented downward by the rod (GB 1465289, GB 2058693, etc.), is used directly as a power telescopic rack.

 In this case, the support legs of the outriggers are fixed at the free ends of the hydraulic cylinder rods. Such outriggers are more compact and have better weight excellence. To fix them at the ends of the sliding beams of the slewing rings, they mainly use the external cylindrical surface of the cylinder body, forming special connecting elements on it for fixing it in the axial and circumferential directions.

 For example, in the well-known analogue of GB 1465289, the hydraulic cylinder is attached to the end of the sliding beam of the slewing device of the self-propelled crane using two removable fingers passed through the corresponding groups of coaxial holes made in a pair of spaced apart plates welded to its body and in the side walls specified beams along which the plates are located. The design of this connection is quite difficult to implement and contributes to an increase in transverse dimensions and a deterioration in the weight excellence of the remote outrigger in general.

 Many of the well-known hydraulic cylinders are standardized and mass-produced. Moreover, their nomenclature is extremely large. In Europe alone, more than 120 firms produce various types of hydraulic cylinders for a wide variety of machinery and equipment.

 However, in some cases, standard hydraulic cylinders for general engineering purposes do not always satisfy developers of special equipment in terms of connecting elements, dimensions, efforts to be developed, degree of sealing of working cavities, weight perfection, ease of assembly and disassembly, and other technical and operational characteristics.

 Of the known analogues of the claimed technical solution, the closest (prototype) can be a double-acting hydraulic cylinder for lowering and lifting the supporting and mounting paws of the remote outriggers of the supporting-rotary device of the ISS-4032 crane, shown in Fig. 19 p. 49 "Manuals for operators (operators) on the safe operation of cranes." M.: NPO OBT, 1995, BBC 32.816N, P62, UDC [221.856.8-5: 658.382.3]: 658.386.05), author-compiler N.A. Bumps.

 The specified hydraulic cylinder contains a housing made in the form of a cylindrical sleeve with a welded bottom, a removable through cover, basing and fastening elements at the end of the cantilever part of the retractable beam of the slewing device of the crane, a single-sided welded hollow rod with a piston and a removable end connector for attaching to it paws with a self-supporting support heel, supporting and sealing elements of movable and fixed joints, a wiper and channels for supplying working fluid to the piston and rod racks with threaded connecting fittings.

 A removable through-case cover in the known hydraulic cylinder is fixed in the inner cavity of its sleeve using a split circular spring ring and secured against rotation in the circumferential direction by means of locking with several radial set screws that are equally spaced around the circumference. Obviously, such compounds contribute to compactness and improve weight design perfection.

 However, with the large geometric dimensions of the hydraulic cylinder, the assembly of the joints of this type is difficult due to the high stiffness of the spring ring. This requires a special device. In addition, they are very sensitive to various manufacturing inaccuracies, leading to the possibility of relative displacement of the edges of the mating parts interacting with the spring ring.

 In this regard, under the action of large working forces developed by the hydraulic cylinder during operation, significant contact stresses are realized on the edges of the parts mating with the spring ring of the circular cross section with the help of it, leading to their crushing.

 As a result of the crushing of these edges, a kind of rolling of the mating parts occurs, which makes it extremely difficult to disassemble them. In practice, there are known cases of transformation for this reason of such detachable connections - into one-piece.

 Execution in the prototype of the piston is removable with lip seals, protected by end washers and fastening with a nut too complicates the design of the hydraulic cylinder, increases its axial and radial dimensions and worsens weight excellence.

 The removable terminal end of the rod for attaching paws to it with a self-supporting support heel is made in the prototype in the form of a corresponding cylindrical bore in its sleeve with an annular groove for a split spring ring of axial paw fixation in the bore.

 The disadvantages of this technical solution are identical to those discussed above for the attachment point of the removable through cover of the cylinder body.

 In the paw mount in the cylindrical bore of the rod sleeve of the specified hydraulic cylinder, it is not provided for rotation from turning in the circumferential direction, which is undesirable, since the relative relative movement of the mating parts during operation contributes to their additional wear.

 For basing and axial fixing of the known hydraulic cylinder at the end of the cantilever part of the retractable beam of the slewing device of the ISS-4032 crane, the outer surface of the cylindrical sleeve of its body and the corresponding restrictive flanges of the ring configuration formed on it are used (see Fig. 3 - p. 27, 4 - p. 29 and 19 - p. 49 of the above "Manual ...").

 Radial fixation of the known hydraulic cylinder is carried out by appropriate tightening with bolts of two spacing collars spaced apart from each other in height.

 The objective of the present invention is to simplify the design, reduce the size, increase the reliability, weight perfection, improve the Assembly and disassembly and other technical and operational qualities of the inventive hydraulic cylinder.

 In accordance with the invention, it is achieved by the fact that in the inventive double-acting hydraulic cylinder for lowering and lifting the supporting and mounting paws of the remote outriggers of crane manipulators, comprising a body made in the form of a cylindrical sleeve with a welded bottom, a removable through cover and an end connector for rigidly fixing it to the end of the console part of the sliding beam of the slewing ring of the crane manipulator installation, one-sided welded hollow rod with a piston and end connector for docking paws with a self-supporting support heel, support and sealing elements of movable and fixed joints, a wiper and channels for supplying working fluid to the piston and rod cavities with threaded connecting fittings, the end connector of the housing is additionally equipped with an outer side formed on its welded bottom and interacting in the composition of the slewing ring of the crane manipulator with the corresponding vertically oriented and open landing bottom from the bottom, located on the end of the console part of the sliding beam of the specified device, a short-base centering shank with a flat annular support and installation end and several equally spaced threaded connecting holes for the shank mounting bolts in the beam socket, a removable through housing cover is coupled to its sleeve by threaded connections, the piston is integral with the rod, and the rod end connector - in the form of a screw cut into it bolt and additionally locked at the interface using an axial set screw, locked by a core in a slot in the thread at three points with a depth of 1 ÷ 1.5 mm at an angle of 30 ÷ 45 degrees, bushings with a developed central threaded hole for a removable paw of a remote outrigger equipped with a concentric located relative to its central threaded hole and open from the outside with a blind recess of cylindrical shape for insertion into it of a bent hook of a lock washer, which secures the paw in the circumferential direction ns after the bend to its corresponding flatted edge washers.

 In addition to the above, the achievement of the task is also ensured by the fact that in the inventive hydraulic cylinder all the structural elements are made of medium-carbon low-alloy steel, hardened by thermomechanical testing, for the radial fixation of the rod with the piston with the possibility of their axial movement, split support rings with an oblique lock of high strength and wear-resistant composite polymer material, for example carbon-filled polyamide, and for sealing movable joints ений - combined seals based on o-rings made of wear-resistant composite polymer material with high antifriction properties, for example, coke-filled fluoroplastic, and compression rings made of elastically deformable oil-resistant material, for example rubber.

 The threaded connecting fittings of the channels for supplying the working fluid to the piston and rod cavities of the inventive hydraulic cylinder are displaced in the circumferential direction with respect to each other, and on the side wall of the sleeve of the housing from the outside between the threaded connecting fittings of these channels are welded mounting bosses with blind threaded holes for fastening on them a hinged one-way hydraulic lock, providing automatic locking of the piston cavity of the hydraulic cylinder in case of emergency damage flexible fluid hoses located in front of the hydraulic lock.

The invention is illustrated by drawings, which depict:
figure 1 is a General view of the inventive hydraulic cylinder;
figure 2 is a view on the left of the hydraulic cylinder;
figure 3 is a view of B from the right to the hydraulic cylinder;
figure 4 - remote element B with an enlarged image of the seal assembly of the piston of the hydraulic cylinder in the sleeve of its body;
figure 5 - remote element G with an enlarged image of the node of the seal of the stem of the hydraulic cylinder in a removable through cover of the sleeve of the housing;
in FIG. 6 is a cross section DD of the hydraulic cylinder at the location of one of the mounting bosses for mounting the hinged one-way hydraulic lock, which automatically locks the piston cavity in case of emergency damage to the flexible fluid supply hoses located in front of it (hydraulic lock is not shown conditionally);
in FIG. 7 - a node for additional fastening of the inventive hydraulic cylinder to the end of the console part of the retractable beam of the support-rotary device of the crane manipulator using axial bolts;
in FIG. 8 is a general view of a fragment of a rotary support device of a crane manipulator with a remote outrigger, in which the paw is retracted into the internal cavity of the hydraulic cylinder;
in FIG. 9 is a general view of a fragment of a rotary support device of a crane manipulator with a remote outrigger, in which the paw is extended to its lowest position;
figure 10 is a General view of a fragment of a remote outrigger, showing the features of the fastening of his paws at the end of the rod of the inventive hydraulic cylinder.

 The inventive hydraulic cylinder 1 double-acting for lowering and lifting the support and mounting paws 2 remote outriggers 3 crane manipulator installation includes a housing 4 made in the form of a cylindrical sleeve 5 with a welded bottom 6, a removable through cover 7 and an end connector 8 for rigidly fixing it to the end of the console part retractable beam 9 of the slewing device 10 of the specified installation, a single-sided welded hollow rod 11 with a piston 12 and an end connector 13 for docking the legs with a self-supporting support fifth 14 minutes, musculoskeletal sealing elements 15-25 mobile and fixed joints, wiper 26 and channels 27, 28 for supplying hydraulic fluid into the piston and rod end 29, 30 with threaded connecting fittings 31, 32.

 As the end connector 8 of the housing 4 of the inventive hydraulic cylinder, its external side surface 33 is used, as in the prototype, while the specified connector is additionally provided with an external manipulator formed on the weld bottom 6 of the housing and interacting with the rotary support device 10 of the crane manipulator with the corresponding vertically oriented and open from the bottom of the landing nest 34, located at the end of the console part of the retractable beam 9 of the slewing device, m centering shank 35 of a cylindrical shape with a flat supporting and mounting end 36 of the ring configuration and several equally spaced in the circumferential direction and open from the outside with blind threaded connecting holes 37 for the bolts 38 of the shank in the socket of the beam.

 The presence of such a shank provides a more reliable, compared with the prototype, fastening of the remote outrigger to the metal structure of the retractable beam of the support-rotary device of the crane manipulator.

 A removable through cover 7 of the hydraulic cylinder body 4 is connected to its sleeve 5 by means of a threaded connection 39. The cover 7 is locked in the sleeve 5 of the housing 4 by means of several radial set screws 40 equally spaced in the circumferential direction, locked by a core in the slot in the thread at three points with a depth of 1 ÷ 1 , 5 mm at an angle of 30 ÷ 45 degrees.

 This connection of a removable through cover with a sleeve of the housing of the inventive hydraulic cylinder is technologically simple enough and has, in comparison with the prototype, much greater strength, reliability, ease and ease of installation and disassembly during operation.

 The piston 12 of the hydraulic cylinder is integral with the rod 11.

 This technical solution allows to significantly simplify the design of the piston rod, to reduce axial and radial dimensions and to obtain a significant gain in its mass.

 The end connector 13 of the rod 11 is made in the form of a sleeve screwed into it on a thread 41 with a developed central threaded hole 42 for a removable paw 2 of the remote outrigger 3. The sleeve 13 is additionally locked at the interface with the rod 11 using an axial set screw 43 locked with a core in the slot into the thread at three points with a depth of 1 ÷ 1.5 mm at an angle of 30 ÷ 45 degrees.

 It is equipped with a cylindrical-shaped blind recess 44 concentrically located relative to its central threaded hole 42 and open from the outside to insert the bent hook 45 of the lock washer 46 into it, which secures the paw 2 in the circumferential direction after bending the edges of the washer onto its corresponding flange 47.

 This embodiment of the connector 13 in the technological plan is quite simple and has, in comparison with the prototype, much greater strength, reliability, ease and convenience of assembly and disassembly of this connection of the mating parts during operation.

 Additional fixation of the connector in the rod using the axial set screw almost completely eliminates the possibility of unauthorized unscrewing it during operation.

 All the structural elements of the inventive hydraulic cylinder are made of medium-carbon low-alloy steel, for example, grade 30HGSA, hardened by thermomechanical processing.

 The specified processing involves the combination of two hardening mechanisms, plastic deformation and hardening in a single technological process.

 Such a combined effect in relation to medium-carbon low alloy steels allows to increase the whole range of their mechanical properties and especially the ductility and viscosity of the material, which is most important for a high-strength state. Compared with conventional processing, the increase in strength during thermomechanical processing is about 10–20%, and the ductility and viscosity characteristics increase by 1.5–2 times.

 Using for the manufacture of power parts of the inventive hydraulic cylinder of high-strength medium-carbon low alloy steel can significantly reduce the size and weight, as well as increase its durability. As a result, the downtime of the crane installation can sharply decrease and its specific productivity per unit mass can increase, the cost of the work performed can be reduced, and the need for appropriate spare parts can be reduced.

 The practice of operating welded structures of the mechanisms of road construction and other machines from high-strength medium-carbon low-alloy steels shows that it is economically feasible to use relatively more expensive high-quality steel compared to low-carbon, but significantly increase the reliability and durability of the structure.

 Due to the increased carbon content, special technologies are used for welding such steels, which provide optimal welding conditions, excluding the appearance of cracks and providing the required ductility, strength and cold resistance in the heat-affected zone.

 Such technologies are now well mastered by the corresponding specialized engineering enterprises and allow to obtain welded joints with properties equal to or close to the properties of the base metal.

 For radial fixation of the piston 12 and the rod 11 with the possibility of their axial movement, split support-guide rings 15, 16, 18, 19, 20, 21, 24 with an oblique lock 48 of high-strength and wear-resistant composite polymer antifriction material, for example carbon-filled polyamide, were used, and for sealing movable joints - combined seals 17, 22, 23 based on O-rings 49, 50, 51 made of wear-resistant composite polymer material with high antifriction properties, for example, coke-filled fluorine asta and biasing the rings 52, 53, 54 of the compliant oil resistant material such as rubber, manufactured by the domestic "AGA-ELKONT".

 Supporting and sealing elements of the aforementioned company, which are distinguished by high quality of manufacture, are compact enough, have relatively low friction, have a long service life, can operate in a wide temperature range, providing relatively good tightness at pressures up to 35 MPa and more, and linear speeds up to 2 m / s. According to their main parameters, they comply with international standards.

 Supporting-guide rings exclude contact and the possibility of scuffing of steel surfaces of the stem and the mirror of the cylinder liner liner and, together with combined seals, increase its working life due to polishing of these surfaces during friction during operation.

 The use of oblique locks in their design almost completely eliminates the possibility of vibrations and creaks in the supports.

 Support and sealing elements of the AGA-ELKONT company significantly improve the lubrication conditions of the moving parts of the hydraulic cylinder, are quite reliable in operation and are convenient for installation and replacement. In this regard, these products currently complete their products more than 100 engineering enterprises.

 In the inventive hydraulic cylinder, the corresponding reservation of supporting-sealing elements of movable joints is implemented. Due to this, the reliability of the hydraulic cylinder is significantly increased and leakage of the working fluid into the environment is almost completely eliminated.

 The threaded connecting fittings 31, 32 of the channels 27, 28 for supplying the working fluid to its piston and rod cavities 29, 30 of the inventive hydraulic cylinder are displaced in the circumferential direction with respect to each other.

 This technical solution provides the convenience of wiring and connecting to the threaded connecting fittings of the hydraulic cylinder of the corresponding pipelines for supplying the working fluid to its piston and rod cavities.

 On the side wall 55 of the sleeve 5 of the housing 4 of the hydraulic cylinder from the outside between the threaded connecting fittings 31, 32 of the channels 27, 28 for supplying the working fluid to its piston and rod cavities 29, 30, support-mounting bosses 56 with blind threaded holes 57 for welding onto them are welded hinged one-way hydraulic lock, which provides automatic locking of the piston cavity of the hydraulic cylinder in case of emergency damage to flexible hoses for supplying working fluid located in front of the hydraulic lock.

 This technical solution allows us to use functionally completed protective and regulatory equipment in a modular design, which is commercially produced by specialized enterprises, to equip the claimed hydraulic cylinder, and on this basis, greatly simplify its design and improve the corresponding quality indicators.

 The installation of the inventive hydraulic cylinder at the end of the cantilever part of the sliding beam 9 of the rotary support device 10 of the crane manipulator is assembled with the paw 2. In this case, the hydraulic cylinder is based in two places: the lateral cylindrical surface 33 of its body 4 in the profiled lodgement 58 thereon and the shank 35 - in the landing nest 34 with the emphasis of its annular end 36 on the mating surface 59 of the beam 9.

 After the corresponding exhibition, the hydraulic cylinder is rigidly fixed in the indicated places with the help of the lining 60, pressing it to the tool tray 58, and the bolts 38 and 61.

 Such fastening of the inventive hydraulic cylinder at the end of the cantilever part of the retractable beam of the slewing ring of the crane manipulator is more reliable than the prototype and almost completely eliminates the possibility of unauthorized rotation of it in the seat and lodgement during operation.

 When the working fluid is supplied to the piston cavity 29 of the inventive hydraulic cylinder, its rod 11 extends from the inner cavity of the housing 4 and, dropping down, presses the paw 2 of the remote outrigger 3 with the self-supporting support heel 14 to the ground, providing the necessary stability of the crane manipulator against tipping over.

 When the working fluid is supplied to the rod cavity 30 of the hydraulic cylinder, its rod 11 is drawn into the inner cavity of the housing 4 and, rising up, takes the supporting heel 14 of the legs 2 from the ground.

 In the design of the inventive hydraulic cylinder, modern domestic materials widely used in engineering are used, optimal technical solutions and standard manufacturing technology.

 With this in mind, it can be repeatedly reproduced according to the documentation developed for it in the conditions of mass production at engineering plants with the necessary experience and equipment.

Currently, Aviaagregat OJSC (Samara) has developed working documentation for the claimed hydraulic cylinder according to the technical specifications of NK Uralterminalmash CJSC, according to which a batch of prototypes of this product has been made for lowering and lifting the support and installation paws of the remote outriggers of the Sinegorets crane-manipulator installation -210 "heavy-duty with the following technical specifications:
The diameter of the piston, mm - 100.

 The diameter of the rod, mm - 80.

 Working stroke, mm - 750.

The working fluid is mineral oil according to GOST 17479.3-85 with a viscosity range during operation from 10 to 500 mm ² / s.

Range of working temperatures, city .:
- environment - from -40 to +50;
- working fluid - from -40 to +80.

 Maximum working pressure, MPa - 16.

 Idling pressure, MPa - not more than 0.5.

Weight kg:
- with the retracted stem - 35.0;
- with a stock issued - 39.0.

 These samples of the inventive hydraulic cylinder have successfully passed autonomous tests. The results of autonomous tests confirmed the correctness of the technical solutions laid down in the design of the inventive hydraulic cylinder, as well as the possibility of obtaining the aforementioned technical effect when implementing the invention, which consists in simplifying the design, reducing dimensions, improving reliability, weight perfection, as well as improving assembly and disassembly and its other technical operational qualities.

 Complex tests of the inventive hydraulic cylinder as part of the Sinegorets-210 crane manipulator are planned for the current year. The decision on the mass production of the inventive hydraulic cylinder will be made in the prescribed manner after the completion of its comprehensive tests.

Claims (5)

1. A double-acting hydraulic cylinder for lowering and lifting the supporting and mounting paws of the remote outriggers of the crane-manipulator installations, comprising a body made in the form of a cylindrical sleeve with a welded bottom, a removable through cover and an end connector for rigidly fixing it at the end of the cantilever part of the retractable support beam rotary device of a crane-manipulator installation, a single-sided welded hollow rod with a piston and an end connector for joining the legs with a self-supporting support heel, op sealing elements of movable and fixed joints, a wiper and channels for supplying working fluid to the piston and rod cavities with threaded connecting fittings, characterized in that the housing end connector is additionally provided with an outer side formed on its welded bottom and interacting with the rotary support devices of a crane-manipulator installation with a corresponding vertically oriented and bottom-mounted landing jack located at the end of the console part a retractable beam, with a short-base centering shank of a cylindrical shape with a flat supporting and mounting end face of a ring configuration and several equally spaced threaded connecting holes for the shank mounting bolts in the beam socket, and a removable through cover is interfaced to the body sleeve by means of a threaded connection made in one piece with the rod, and the rod end connector - in the form of a sleeve screwed into it on the thread with a developed center with a threaded threaded hole for the foot of the remote outrigger, additionally locked at the place of mating with the rod with the help of an axial set screw locked by a core in the slot in the thread at three points with a depth of 1-1.5 mm at an angle of 30-45 °, for radial fixing of the piston and rod , with the possibility of their axial movement, used split support-guide rings with an oblique lock made of high-strength and wear-resistant composite polymer antifriction material, for example, carbon-filled polyamide, and for sealing zhnyh compounds - combined seal based sealing rings of wear-resistant polymeric composite material with good antifriction properties, for example polytetrafluorethylene koksonapolnennogo and biasing ring of an elastically deformable oil resistant material such as rubber. 2. The hydraulic cylinder according to claim 1, characterized in that the rod end attachment is provided with a cylindrical deaf depression concentrically located relative to its central threaded hole and open from the outside to insert a bent hook of the lock washer into it, which secures the paw of the remote outrigger in the circumferential the direction after bending to its corresponding flatter the edges of the washer. 3. The hydraulic cylinder according to claim 1, characterized in that the power structural elements are made of high-quality medium-carbon low-alloy steel, hardened by thermomechanical processing. 4. The hydraulic cylinder according to claim 1, characterized in that in it the threaded connecting fittings of the channels for supplying the working fluid to its piston and rod cavities of the hydraulic cylinder are displaced in the circumferential direction with respect to each other. 5. The hydraulic cylinder according to claim 1, characterized in that in it on the side wall of the sleeve of the housing from the outside between the threaded connecting fittings of the channels for supplying the working fluid to its piston and rod cavities, support-mounting bosses with blind threaded holes are welded for mounting the mounted ones one-way hydraulic lock, providing automatic locking of the piston cavity in case of emergency damage to flexible hoses for supplying working fluid located in front of the hydraulic lock.

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