PIPE SEALING APPARATUS AND JACK

Abstract: Pipe sealing apparatus and a jack for operating the sealing apparatus to effect repairs in sewer pipes and the like are disclosed. The sealing apparatus comprises a col­ lapsible pipeliner (16, 18, 20, 22) constructed in a plurality of arcuate segments that define a closed loop which can be moved from a collapsed state in which the loop can be located in a damaged pipe to an erect state in which the loop defines a rigid pipeliner with a cylindrical outer sur­ face. A compressible sealing material such as urethane foam is secured to the segments so that the sealing material covers the cylindrical outer surface when the loop is moved into the erect state. When the pipeliner is erected the seal­ ing material is compressed between the cylindrical outer surface of the erected pipeliner and a damaged inner sur­ face of the pipe to provide a fluid-tight seal. The pipeliner can be erected by expanding the closed loop vertically and thereafter horizontally until the loop assumes an oversized state from which the loop is biased to move into a locked-­ erect state of relatively smaller dimension. A hydraulically operated jack (30) for expanding the loop is described.

Description: The invention relates to sealing apparatus for use in repairing sewer pipes and the like, and to a hydraulically operated jack for use in operating the sealing apparatus during pipe repair. The jack disclosed is also useful generally for erecting collapsible tunnel liner sections constructed in a plurality of arcuate segments which define rigid shell-like cylindrical liners when erect. Segmented, closed loop tunnel or pipeliners are known, and reference is made to my U.S. patent No. 4,124,985 which discloses such a tunnel liner. These tunnel liners comprise a plurality of arcuate segments which are hingedly connected to define a closed loop which in collapsed state is small enough in cross-section to be transported through previously erected tunnel liner sections to a location where an additional tunnel liner section is to be erected. Once at the desired location, the tunnel liner section is expanded to define a rigid cylindrical structure. In the device of my U.S. patent, the tunnel liner section is moved from a collapsed state to an intermediate state in which the arcuate segments define a cylindrical structure having an inner diameter greater than the ultimate desired diameter for the erected tunnel liner section, and in this oversized condition the arcuate segments are positioned to self-lock when released, to assume the final erect state. My U.S. patent No. 4,124,985 also discloses a method of erecting a collapsible tunnel liner section. The method involves placing deflated air bags in the stack formed by the collapsed loop of tunnel liner segments, and then inflating the bags to expand the loop outwardly to the oversized condition. The air bags are then deflated (leaving the tunnel liner section in the fully erect state), and moved for use in the next section to be assembled. A disadvantage associated with the use of air bags is that considerable care and time must be taken to ensure that they are properly placed in the cavity defined by the collapsed tunnel liner and functioning properly. Another method used to erect tunnel liners involves placing a vertically oriented hydraulic cylinder in the cavity defined by the collapsed tunnel liner sections at both ends thereof. The cylinders are then used to expand the loop vertically thereby increasing the size of the interior cavity and allowing workmen to access the inner surface of the loop. The workmen then press out the side segments of the tunnel liner section with jacks to completethe erection. This method has proven somewhat dangerous because of the instability of the tunnel liner section and its oversized condition and because of the lack of effective bracing of the cylinders. The present invention seeks to provide method and apparatus for sealing a damaged pipe or tunnel, which apparatus incorporates much of the structure of a collapsible tunnel or pipeline or section, and seek to provide a novel hydraulically-powered jack for use in assembling the apparatus and also for use generally in assembling collapsible tunnel or pipeliner sections. Accordingly, in a first aspect, the invention provides sealing apparatus comprising a collapsible pipeliner constructed in a plurality of arcuate segments. The segments are hingedly connected to define a closed loop which can be moved from a collapsed state in which the loop is sufficiently small in cross-section to be located in a damaged pipe to an erect state in which the loop defines a rigid structure with a generally cylindrical outer surface. A compressible sealing material (such as foamed urethane) is secured to the segments so that the sealing material covers at least a portion of the cylindrical outer surface when the pipeliner is erected. When the collapsible pipeliner is located within a damaged pipe portion in a collapsed state and then moved into the erect state, the sealing material is compressed between the cylindrical outer surface of the erected pipeliner and a damaged inner pipe surface to seal the damaged pipe portion. In a second aspect the invention provides a jack specifically adapted for use in erecting segmented, closed loop tunnel liners (or pipeliners). The jack can be used with any collapsible tunnel liner of this type in which the loop defined by the tunnel liner segments can be moved from a collapsed state, in which the segments define a stack with an open space for receiving the jack, to an erect state, at least in part by relative displacement of loop portions along two mutually perpendicular axes. More specifically, the jack is intended for use with a tunnel liner loop that can be erected by displacing a first loop portion relative to a second loop portion through a first predetermined distance along the first axis (for example, the displacement of top and bottom segments of a loop along a vertical axis), and then displacing a third loop portion relative to a fourth loop portion through a second predetermined distance along a second axis perpendicular to the first axis (and continuing the example, by displacing oppositely-disposed loop side segments horizontally). The jack is thus useful in expanding a collapsible tunnel liner as described in my U.S. patent No. 4,124,985 from a collapsed state to its oversize condition. The jack comprises a carrier which can be physically disposed in the cavity defined by a collapsed tunnel liner, and first, second, and third pushing elements. A first hydraulic cylinder secured to the carrier can be activated to advance the first pushing element in a first direction (typically vertically). A second hydraulic cylinder secured to the carrier can be activated to advance the second pushing element in a second direction perpendicular to the first direction (typically horizontal). A third hydraulic cylinder secured to the carrier can be activated to advance the third pushing element in a third direction, opposite to the second direction. When the carrier is disposed in the cavity of a collapsed tunnel liner section, the direction of motion of the pushing elements can be oriented coincident with the axes along which the tunnel liner loop portions must be advanced to move the tunnel liner into an erect state, and the hydraulic cylinders activated to displace the first and second loop portions mentioned above to the first predetermined distance then to advance the third and fourth loop portions through the second predetermined distance. In the context of a collapsible tunnel liner section as described in my U.S. patent No. 4,124,985 the jack can be used first to expand a tunnel liner vertically and then horizontally until an oversized condition is achieved, and thereafter the jack can be disengaged to permit the tunnel liner segments to lock into an erect structure. The invention'will be better understood with reference in which: Fig. 1 is a side perspective view of a jack constructed according to the invention, in partially contracted condition; Figs. 2-3 are cross-sectional views along the line 2-2 illustrating a turning mechanism (oriented in two distinct states) used to rotate certain hydraulic cylinders of the carrier between operative and inoperative positions; Fig. 4 is a front perspective view of pipe sealing apparatus comprising a segmented pipeliner, partially erected with the jack of Fig. 1; Fig. 5 is a front perspective view of the sealing apparatus fully erected; and, Figs. 6-8 are side perspective views illustrating alternative embodiments of a jack constructed accoridng to the invention. Reference is made to Fig. 4 which illustrated sealing apparatus 10 being erected with a hydraulically operated jack 12 to seal damaged inner surfaces of a large pipe 14. The sealing apparatus 10 comprises a closed loop pipe or tunnel liner defined by a numberof arcuate pipe liner segments, namely, a top segment 16, a bottom segment 18, a first pair of side segments 20 and an oppositely disposed pair of side segments 22. The segments can be constructed of steel, concrete, PVC plastic or any other suitable material. The segments are shown in Fig. 4 in a collapsed state in which they effectively define a closed loop stack with an opening 24 in which the jack 12 is received. In Fig. 5 the segments have been erected using the jack 12 to define a rigid tunnel liner section of generally cylindrical shape. Two sheets of foamed urethane are adhesively secured to the segments. When the segments are erected into a rigid pipeliner, as illustrated in Fig. 5, the sealing material 24 is compressed between the generally cylindrical outer surface (not specifically indicated) of the erected segments and the damaged inner surface 26 of the pipe 14. The pipeliner and the sealing sheets 25 must of course be dimensioned appropriately. In particular, if a pipe or tunnel liner as illustrated in my U.S. patent No. 4,124,985 is used, one must ensure that the outer diameter of the pipeliner in its oversized condition does not exceed the liner diameter of the pipe 14 being repaired. It will also be appreciated that the sheets of sealing material 25 will have to compress sufficiently to accomodate the structure of the segments in the oversized condition. The jack 12 is better illustrated in the views of Figs. 1-3 where it can be seen to comprise a hollow steel carrier 28 with a base 29 having a rounded bottom 31 con; forming in curvature to the bottom segment 18 of the sealing apparatus 10, two vertically oriented hydraulic cylinders 30, and two horizontally oriented hydraulic cylinder assemblies 32. Each of the cylinder assemblies 32 comprises a pair of horizontally oriented hydraulic cylinders 34,36 which are rigidly secured to one another and aligned to advance metal push pads 38,40 in opposite directions when hydraulically activated. The hydraulic cylinders 30,34,36 are of a conventional type that is spring-biased to retract its piston when application of hydraulic fluid is discontinued so that once a pipeliner is erected with the jack 12 a drop in pressure in hydraulic feed liners causes the cylinder pistons and consequently the pushing elements to retract automatically from the erect pipeliner. The jack 12 is preferably compact to fit easily into the open space within a collapsed loop of pipeliner segments. In pipeliners such as that of the sealing apparatus 10, the segments when collapsed define an opening whose vertical extent is greater than its horizontal extent. The jack 12 has consequently been constructed so that its overall horizontal width can be reduced by rotating the assemblies 32 between inoperative positions (illustrated in ghost outline in Fig. l)in which the hydraulic cylinders 34, 36 are effectively retracted and operative positions (illustrated in Fig. 1 in solid lines). In the inoperative positions the cylinders 38,40 are disposed substantially parallel to the longitudinal axis A of the carrier 28, substantially perpendicular to the directions in which the cylinders 38,40 normally act when in the operative positions. The carrier 28 houses a rotation assembly 48 (illustrated in the views of Figs. 2-3) which serves to rotate the cylinder assemblies 32 between the operative and inoperative positions. Each of the cylinders assemblies 32 is mounted on a vertical shaft 50, rotatably secured to the carrier 28. Winged collars 52, 54 are secured one to each shaft 50, and used in rotating the shafts 50. Two substantially identical connecting arms 56 are pivotally connected to the collars 52, 54 as illustrated to ensure that the cylinder assemblies 32 rotate in unison and by the same amount. A hydraulic cylinder 62 with an end 64 pivotally secured to the carrier 28 and a piston end 66 pivotally secured to the wing collar 54 can be hydraulically activated to rotate the cylinder assmeblies 32 between the operative and inoperative positions, the operative position being achieved by full-extension of the cylinder 62, and the in operative position being achieved by full contraction of the cylinder 62. (Metal stops can be used instead to engage the winged collars 52,54 to limit rotation, but would have to be constucted to withstand very significant forces and are not preferred). The various hydraulic cylinders of the jack 12 are operated from hydraulic feed lines 42,44, 46. The vertical cylinders 30 are simultaneously operated from the line 42, and the horizontal cylinders 34, 36 from the line 44. The cylinder 62 is expanded by hydraulic press- ure in the line 42 (and its expansion is closely tied to that of the horizontal cylinders 24, 26), and contracted by pressure applied to the line 46. A valve 64 directs hydraulic fluid in the line 44 between the horizontal cylinders 34, 36 and the cylinder 62 so that expansion of the horizontal cylinders 34, 36 does not begin until the horizontal cylinders assemblies 32 are first rotated to their operative positions. The valve 64 has a first internal pathway which continuously directs hydraulic fluid to and from the cylinder 62 whereby the cylinder 62 always expands (to the extent otherwise possible) when pressure is applied to the line 44. The valve 64 has a second internal pathway with a spring-biased check valve that freely permits the flow of hydraulic fluid from the horizontal cylinders 34, 36 but only permits flows into the cylinders 34, 36 when a predetermined pressure is achieved in the valve 64. Thus, when hydraulic fluid is applied to line 44 the hydraulic cylinder 62 alone expands, until fully extended and a build-up of back pressure occurs in the fluid line 66. When the back pressure exceeds the predetemined level needed to open the internal check valve, the hydraulic cylinders 34, 36 are then expanded. When pressure is no longer applied to the line 44 the cylinders 34, 36 retract under their spring bias, and the cylinders assemblies 32 can then be rotated to their inoperative positions by applying hydraulic pressure to the line 46, contracting the cylinder 62. A suitable valve for such purposes is the Enerpac V161, of Enerpac Butler, a division of Applied Power Inc., of Wisconsin, U.S.A. To repair a pipe the sealing apparatus 10 is transported in its collapsed state to the location in the pipe where the fault has occured, and oriented for expansion into the erect state. The jack 12 is then disposed in the opening 24 with the base 31 of the carrier 28 resting against the bottom segment 18 of the sealing apparatus 10. The bottom surface of the base 21 is shaped to conform sub- stantially to that of the bottom to improve the bracing of the carrier 28 against the segments. The vertically oriented hydraulic cylinders 30 are then activated to advance pushing pad 70 towards the upper segment 16 of the sealing apparatus 10. The upper segment 16 is advanced vertically until the sheets of sealing material 25 are compressed against the damaged pipe portions 26. With the incident horizontal expansion of the space 24 the hydraulic assemblies 32 can then be positioned to press out the side segments 20,22. The cylinders assemblies 32 are rotated to the operative positions illustrated in solid lines in Fig. 1, and the cylinders 34, are then activated to move pushing elements 38 in a direction C and the cylinders 36 simultaneously activated to move the pushing elements 36 in an opposite direction B, (the directions B and, Cbeing substantially perpendicular to the axis A of the carrier 28). The pushing-elements 38,40 engage the side segments 20,22 respectively, and advance the side segments 20,22 towards the position illustrated in Fig. 5, and into the oversized condition of the sealing apparatus 10. The hydraulic pressure applied to the cylinders 30,34 is then released, permitting the cylinders to then retract under their spring bias, and simultaneously permitting the sealing apparatus 10 to assume its erect state. Because the foamed urethane sealing material is compressed against the damaged inner surface 26 of the pipe 14, the surface 26 is sealed. The cylinder assemblies 32 are then returned to the inoperative position so that the jack 12 can be used elsewhere on the pipe 14 or returned to storage. In small pipes the length of a conventional hydraulic cylinder may well exceed the clearance between upper and lower pipe liner segments in their collapsed state. The carrier 12 with its vertically oriented hydraulic cylinders 30 cannot be used under such circumstances. A jack 72 which can be appropriately dimensioned for such application is illustrated in the view of Fig. 6. The jack 72 comprises an elongate carrier 74 having a longitudinal axis D and a rounded base 76 adapted to be rested in a collapsed pipe or tunnel liner. Two substantially identical vertical pushing assemblies 78,80 are secured to the carrier 74 as illustrated. A horizontal assembly 82 is mounted to the top of the carrier 74. The vertical pushing assembly 78 comprises a hydraulic cylinder 84 rigidly secured to the carrier 74 and aligned substantially parallel to the axis D, a metal pushing pad 86 and various mechanical linkage means for transforming movement of the piston 84 in a direction parallel to the axis D into a substantially vertical movement of the pushing pad 86. The piston 84 is of the type described above which is spring-biased to return to a contracted state when no longer hydraulically actuated. The linkage means include a yoke 88 secured to the piston of the cylinder 84, a first pivot arm 90 pivotally mounted at one end in the yoke 88 and pivotally connected at another end to the pushing element 86,. and a second pivot arm 92 pivotally connected at one end to the pushing element 86 and pivotally connected at another end to the connector 74 by means of a pivot pin 94. The motion of the pushing pad 86 under the influence of the cylinder 84 is not a pure displacement in a vertical direction, but involves rotation of pushing element 86 about the pivot pin 94. As the vertical pushing assembly 78,80 is substantially identical, the visible components of the assembly 80 have been labelled with corresponding reference numerals but the assembly 80 will not be described. The horizontal pushing assembly 82 is constructed as two distinct pushing assemblies 96,98. Each of the pushing assemblies 96,98 comprises a hydraulic cylinder 100 which lies substantially parallel to the axis D, a pushing pad 102, and linkage means comprising first and second pivot pin 108. The pushing assemblies 96,98 are analagous in structure and function to the pushing assemblies 78,80, and motion of the pistons of the cylinders 10,0 in the general direction of the axis D is transformed at least in part into motion of the pushing elements 102, horizontally but in opposite directions. The two pivot arms 106 and two pivot pins 108 can be replaced by a single pivot arm extending continously between the pads 102, and pivotally connected to the carrier 74 by a single pivot pin centrally located in the pivot arm. In practice, use of a single pivot arm has been found to necessitate lateral bracing of the carrier 74 where unequal forces are brought to bear on each of the pads 102. This problem is substantially obviated where the cylinders 100 are substantially identical, separate pivot arms 106 and pivot pins 108 are used, and the cylinders 100 are actuated from a single hydraulic fluid line. The jack 72 is used in substantially the same manner as the jack 12 described above. However, only two hydraulic fluid lines 110, 112 are required. The fluid line 110 provides hydraulic fluid simultaneously to each of the vertical pushing assemblies 78,80 and the line 112 provides hydraulic fluid simultaneously to each of the hydraulic cylinders 100. It will be appreciated that the carrier 74 can be dimensioned to be smaller than illustrated, and could in fact be a thick metal plate with the hydraulic fluid lines 110,112 secured to the exterior plate. Figs. 7 and 8 illustrate alternative embodiments 114,116 of hydraulically operated jacks adapted for use in the sealing apparatus of the invention. The jacks 114,116 involve a combination of features already discussed in detail with respect to the jacks 12.72 and consequently will not be discussed in detail. Instead, features identical to those described have been labelled with like reference numerals. Very briefly, the jack 114 comprises vertically oriented hydraulic cylinders 30 surmounted with pushing pads 70. To the top of the carrier illustrated are secured the horizontal pushing assemblies 96,98. As the cylinders 30, and 100 are of the type which are spring-biased to retract when not subject to hydraulic fluid pressure, only two fluid lines 110, 112 are required to operate the cylinders 30, 100, the line 110 providing hydraulic fluid simultaneously to the vertical cylinders 30, and the line 112 providing hydraulic fluid simultaneously to the hydraulic cylinders 100. The jack 116 is provided with the vertical pushing assemblies 78,80 described above which transforms longitudinal motion of the hydraulic cylinders 84 into vertical displace of pushing pads 86. The jack 116 is also provided with the rotating cylinder assemblies 32 of jack 12 for use in horizontally expanding closed loop tunnel or pipeliners. The vertical pushing assemblies 78,80 are operated from a single hydraulic fluid line 42, while the cylinder assemblies 32 are operated from two lines, 44,46. The line 44 serves both to rotate the cylinder assemblies 32 from the inoperative to the operative positions and to advance the pistons of the cylinders 34,36 horizontally. The line 46 serves to restore the cylinder assemblies 32 to the inoperative position in the manner described above. The various jacks 12,72 114, 116 have been described with reference to the sealing apparatus 10. However, it is contemplated that the jacks can be used generally in the erection of segmented, closed loop tunnel or pipeliners which can be assembled by displacing top and bottom loop segments along a vertical axis, and then by displacing oppositely-disposed side segments along a horizontal axis. Although horizontal and vertical axes ahve been relied upon throughout to illustrate the realtive orientation of the hydraulic cylinders of the various jacks, it will be appreciated that the jacks described can be used to erect vertically inclined tunnel or pipeliners which can be erected by displacing oppositely-disposed loop protions along mutually perpendicular axes.

Claims: I CLAIM: 1. Sealing apparatus for use in sealing damaged pipes, comprising: a collapsible pipe liner constructed in a plurality of arcuate segments hingedly connected so that the segments define a closed loop which can be moved from a- collapsed state in which the loop can be located in a damaged pipe to an erect state in which the loop defines a rigid, erected pipe liner of generally cylindrical shape with a generally cylindrical outer surface; and, compressible sealing material secured to the segments so that the sealing material covers at least a portion of the cylindrical outer surface when the loop is moved into the erect state; whereby, when the collapsible pipe liner is located within a damaged pipe portion in the collapsed state and then moved into the erect state, the sealing material is compressed between the cylindrical outer surface of the erected pipe liner and a damaged inner surface of the damaged pipe portion to, seal the damaged pipe portion. 2. Sealing apparatus as claimed in claim 1 in which the sealing material defines a substantially cylindrical shell covering the-cylindri-cal outer surface of the erected pipe¯liner. 3. A collapsible tunnel liner in combination with a jack for use in erecting the tunnel liner, in which: the collapsible tunnel liner comprises a plurality of arcuate segments hingedly connected so that the segments define a closed loop which can be moved from a collapsed state in which the segments define a stack with an open space for receiving the jack, to an erect state, in which the segments define an erected tunnel liner, at least in part by movements comprising displacing a first loop portion relative to a second loop portion through a first predetermined distance along a first axis and then displacing a third loop portion relative to a fourth loop portion through a second predetermined distance along a second axis perpendicular to the first axis; the jack comprises a carrier located in the open space in the stack against the second loop portion; ; the jack comprises first hydraulically-operated jack means for use in displacing the first loop portion relative to the second loop portion by the first predetermined distance, including a first hydraulic cylinder secured to the carrier and a first pushing element coupled to the piston of the first hydraulic cylinder so that the first pushing element can be advanced by the first hydraulic cylinder to displace the first loop portion along the first axis, the jack comprises second hydraulically-operated jack means for use in di-splacing the third loop portion relative to the fourth loop portion by the second predetermined distance, including a second hydraulic cylinder secured to the carrier and a second pushing element coupled to the piston of the second hydraulic cylinder so that the second pushing element can be advanced by the second hydraulic cylinder to dispalce the third loop portion in a first direction, along the second axis and including a third hydraulic cylinder secured to the carrier and a third pushing element coupled to the piston of the third hydraulic cylinder so that the third pushing element can be advanced by the third hydraulic cylinder to displace the' fourth loop portion along the second axis in a second direction opposite to the first direction along the second axis. 4. The combination of claim 3 in which: the second and third hydraulic cylinders are rotatably secured to the carrier, and rotable between inoperative positions in which the second and third cylinders are transversely disposed relative to each of the first and second axes and operative positions in which the second and third hydraulic cylinders are directed generally in the first and second directions so that the pistons of the second and third hydraulic cylinders move in the first and second directions when hydraulically activated; and, the second jack means include means attached to the carrier for selectively rotating the second and third cylinders between the operative and inoperative positions. 5. The combination of claim 3 in which: the first hydraulic cylinder is rigidly secured to the carrier and positioned so that the piston of the first cylinder advances when hydraulically activated along a third axis substantially perpendicular to the first and second axes; and, the first jack means include linkage means coupling the first pushing element to the piston of the first hyd- raulic cylinder for transforming movement of the piston of the first cylinder along the third axis into movement of the first pushing element parallel to the first axis. 6. The combination of claim 3 in which: the second and third hydraulic cylinders are rigidly secured to the carrier so that the pistons of the second and third hydraulic cylinders move when hydraulically actuated perpendicular to the first and second axes; and, the second jack means include linkage means for coupling the pistons of the second and third hydraulic cylinders to the second and third pushing elements for transforming movement of the piston of the second hydraulic cylinder perpendicular to the first and second axes into movement of the second pushing-element parallel to the second axis and for transforming movement of the piston of the third hydraulic cylidner perpendicular to the first and second axes into movement of the third pushing element parallel to the second axis. 7. A jack for use in erecting collapsible tunnel liners and the like, comprising: a carrier shaped to be located in a collapsed tunnel liner; first, second and third pushing elements; a first hydraulic cylinder secured to the carrier and having a first piston coupled to the first pushing element so that the first pushing element can be advanced when the first piston is hydraulically activated; a second hydraulic cylinder secured to the carrier and having a second piston coupled to the second pushing element so that the second element can be advanced in a second direction to the first axis when the second piston is hydraulically activated; and, a third hydraulic cylinder secured to the carrier and having a third piston coupled to the third pushing element so that the third pushing element can be advanced in a third direction opposite to the second direction when the third piston is hydraulically activated. 8. The jack of claim 7 in which: the second and third hydraulic cylinders are rotatably secured to the carrier, and are rotatable between inoperative positions in which the second and third cylinders are substantially retracted to reduce the overall width of the jack as measured in the second and third directions and operative positions in which the first and second hydraulic cylinders are aligned in the second and third directions; and, the jack includes means secured to the carrier for selectively rotating the second and third hydraulic cylinders between the operative and inoperative positions. 9. The jack of claim 7 in which: the second and third cylinders are rigidly secured to the carrier and positioned so that the second and third pistons move substantially perpendicular to the first and second directions; and, the jack includes linkage means coupling the second and third pushing elements to the second and third pistons for transforming movement of the second piston perpendicular to the first and second axis into movement of the second pushing element in the second direction and for transforming movement of the third piston perpendicular to the first and second axes into movement of the third pushing element in the third direction. 10. The jack of claim 7 in which: the first cylinder is rigidly secured to the carrier in a position such that the first piston moves substantially perpendicular to the first and second axes; and, the jack includes linkage means coupling the first piston to the first pushing element for transforming movement of the first piston along the axis perpendicular to the first and second axis into movement of the first pushing element along the first axis.

Inventors: MAIMETS, LEMBIT
Applicants: MAIMETS, LEMBIT
Application year: 1982
Main classification: F16L55
IPC codes: E21D11, F16L55, E21B29