APPARATUS AND METHOD FOR LIFTING A

HEAVY MACHINERY

PRIOR APPLICATION

[0001] The present application claims priority from U.S. provisional patent application No. 62/783,895, filed on December 21 , 2018, and entitled “HYDRAULIC CYLINDER ASSEMBLY”, the disclosure of which being hereby incorporated by reference in its entirety.

TECHNICAL FIELD

[0002] The technical field relates to hydraulic cylinder assemblies, and more particularly to hydraulic cylinder assemblies comprising coaxial hydraulic cylinders, for instance to be used in lifting apparatuses, to lifting apparatuses comprising a hydraulic cylinder assembly and to methods for lifting heavy machinery.

BACKGROUND

[0003] Lifting apparatuses that are used for instance to lift heavy machinery may comprise a plurality of hydraulic cylinders which are configured in an adjacent configuration. For instance, dual assemblies of hydraulic cylinders are used to provide the lifting apparatus with a mechanical redundancy, meaning that in case one of the hydraulic cylinders breaks (for instance in case of a leakage of a hydraulic circuit of one of the hydraulic cylinders), at least another hydraulic cylinder can ensure the lifting and/or the support of the heavy machinery.

[0004] However, hydraulic cylinder assemblies with adjacent hydraulic cylinders are usually cumbersome, so that they might not be adapted in some situations wherein the available spacing is limited. Moreover, the load of the heavy machinery supported by the adjacent hydraulic cylinders might be centered between the adjacent cylinders, so that the breaking of one of the hydraulic cylinders might unbalance the lifting of the heavy machinery and thus result in a fall of the heavy machinery.

[0005] In view of the above, there is a need for a hydraulic cylinder assembly which would be able to overcome or at least minimize some of the above- discussed prior art concerns.

BRIEF SUMMARY

[0006] It is therefore an aim of the present invention to address the above- mentioned issues.

[0007] According a general aspect, there is provided a hydraulic cylinder assembly having a longitudinal axis and comprising an outer barrel defining a piston-receiving cavity and having an inner peripheral surface; an inner barrel coupled to the outer barrel, extending in the piston-receiving cavity thereof and having an outer peripheral surface facing at least partially the inner peripheral surface of the outer barrel, and an opposed inner peripheral surface, the inner barrel separating the piston-receiving cavity into an outer fluid-receiving chamber and an inner fluid-receiving chamber; an outer piston at least partially inserted in the outer fluid-receiving chamber and comprising a sealing end portion having a fluid-contacting surface, the sealing end portion sealingly contacting the inner peripheral surface of the outer barrel and the outer peripheral surface of the inner barrel and being translatable within the outer fluid-receiving chamber along the longitudinal axis; an inner piston at least partially inserted in the inner fluid receiving chamber and comprising a sealing end portion having a fluid-contacting surface, the sealing end portion sealingly contacting the inner peripheral surface of the inner barrel and being translatable within the inner fluid-receiving chamber along the longitudinal axis. A surface area of the fluid-contacting surface of the sealing end portion of the inner piston is substantially equal to a surface area of the fluid-contacting surface of the sealing end portion of the outer piston so that, in use, the sealing end portions of the inner and outer pistons translate simultaneously within the corresponding one of the inner and outer fluid-receiving chambers. [0008] According to another general aspect, there is provided a hydraulic cylinder assembly having a longitudinal axis and comprising an outer barrel defining a piston-receiving cavity and having an inner peripheral surface; an inner barrel coupled to the outer barrel, extending in the piston-receiving cavity thereof and comprising an outer peripheral surface facing at least partially the inner peripheral surface of the outer barrel, and an opposed inner peripheral surface, the inner barrel separating the piston-receiving cavity of the outer barrel into an outer fluid receiving chamber and an inner fluid-receiving chamber; an outer piston at least partially inserted in the outer fluid-receiving chamber and comprising: a sealing end portion sealingly contacting the inner peripheral surface of the outer barrel and the outer peripheral surface of the inner barrel and translatable within the outer fluid-receiving chamber along the longitudinal direction, the sealing end portion having a fluid-contacting surface and an opposed rod-facing surface, and an outer piston rod comprising a rod body mounted to the sealing end portion and extending longitudinally from the rod-facing surface thereof. The hydraulic cylinder assembly further comprises an inner piston at least partially inserted in the inner fluid-receiving chamber and comprising a sealing end portion sealingly contacting the inner peripheral surface of the inner barrel and translatable within the inner fluid-receiving chamber along the longitudinal direction, the sealing end portion having a fluid-contacting surface and an opposed rod-facing surface, and an inner piston rod comprising a rod body mounted to the sealing end portion and extending longitudinally from the rod-facing surface thereof. Each one of the inner piston rod and the outer piston rod has a head-supporting end portion, the head supporting end portions of the inner and outer piston rods being connected to one another so that, in use, the sealing end portions of the inner and outer pistons translate simultaneously within the corresponding one of the inner and outerfluid- receiving chambers.

[0009] According to another general aspect, there is provided a kit for forming a hydraulic cylinder assembly according to the present disclosure.

[0010] According to another general aspect, there is provided a lifting apparatus for lifting heavy machinery, the lifting apparatus comprising a hydraulic cylinder assembly according to the present disclosure, and a lifting body engaged with the inner piston and the outer piston.

[0011] According to another general aspect, there is provided a method for lifting and lowering a heavy machinery, the method comprising providing a lifting apparatus comprising a hydraulic cylinder assembly having a longitudinal axis and comprising: an outer barrel defining a piston-receiving cavity and having an inner peripheral surface; an inner barrel coupled to the outer barrel, extending in the piston-receiving cavity thereof and comprising an outer peripheral surface facing at least partially the inner peripheral surface of the outer barrel, and an opposed inner peripheral surface, the inner barrel separating the piston-receiving cavity into an outer fluid-receiving chamber and an inner fluid-receiving chamber; an outer piston at least partially inserted in the outer fluid-receiving chamber and comprising a sealing end portion sealingly contacting the inner peripheral surface of the outer barrel and the outer peripheral surface of the inner barrel, the sealing end portion having a fluid-contacting surface and an opposed rod-facing surface, and an outer piston rod comprising a rod body mounted to the sealing end portion and extending longitudinally from the rod-facing surface thereof; an inner piston at least partially inserted in the inner fluid-receiving chamber and comprising a sealing end portion sealingly contacting the inner peripheral surface of the inner barrel, the sealing end portion having a fluid-contacting surface and an opposed rod-facing surface, and an inner piston rod comprising a rod body mounted to the sealing end portion and extending longitudinally from the rod-facing surface thereof; a lifting body engaged with the inner piston rod and the outer piston rod and supporting the heavy machinery. The method further comprises injecting inner and outer fluids simultaneously into the inner fluid-receiving chamber and the outer fluid-receiving chamber of the hydraulic cylinder assembly; translating substantially simultaneously the sealing end portions of the inner and outer pistons respectively within the inner and outer fluid-receiving chambers along the longitudinal direction; and raising the lifting body so as to lift the heavy machinery.

[0012] According to another general aspect, there is provided a hydraulic cylinder assembly comprising an outer barrel defining a piston-receiving cavity, an inner barrel inserted in the piston-receiving cavity of the outer barrel and separating the piston-receiving cavity of the outer barrel into an outer fluid-receiving chamber and an inner fluid-receiving chamber, an outer piston inserted in the outer fluid receiving chamber and translatable therein with respect to the inner barrel, the outer piston extending between the outer barrel and the inner barrel and having a fluid-contacting surface extending along a surface area and an inner piston inserted in the inner fluid-receiving chamber and translatable therein with respect to the inner barrel, the inner piston contacting an inner surface of the inner barrel and having a fluid-contacting surface extending along a surface area substantially equal to the surface area of the fluid contacting surface of the outer piston. Each one of the inner piston and the outer piston has a head supporting end portion, the head supporting end portions of the inner piston and the outer piston being connected to one another in a manner such that the inner piston and the outer piston translate simultaneously with respect to the inner barrel.

[0013] According to another general aspect, there is provided a hydraulic cylinder assembly comprising an outer barrel defining a piston-receiving cavity, an inner barrel inserted in the piston-receiving cavity of the outer barrel and separating the piston-receiving cavity of the outer barrel into an outer fluid-receiving chamber and an inner fluid-receiving chamber, an outer piston inserted in the outer fluid receiving chamber and translatable therein with respect to the inner barrel, the outer piston extending between the outer barrel and the inner barrel and sealingly contacting an inner peripheral surface of the outer barrel and an outer peripheral surface of the inner barrel to prevent a fluid inserted in the outer fluid-receiving chamber to flow outwardly therefrom through the outer piston and a contact between the outer piston and the inner peripheral surface of the outer barrel and the outer peripheral surface of the inner barrel and an inner piston inserted in the inner fluid-receiving chamber and translatable therein with respect to the inner barrel, the inner piston sealingly contacting an inner peripheral surface of the inner barrel to prevent a fluid inserted in the inner fluid-receiving chamber to flow outwardly therefrom through the inner piston and a contact between the inner piston and the inner peripheral surface of the inner barrel. Each one of the inner piston and the outer piston has a head supporting end portion, the head supporting end portions of the inner piston and the outer piston being connected to one another in a manner such that the inner piston and the outer piston translate simultaneously with respect to the inner barrel.

[0014] According to another aspect, there is provided a kit for forming a hydraulic cylinder assembly according to the present disclosure.

[0015] According to another aspect, there is provided a lifting apparatus for lifting heavy machinery. The lifting apparatus comprises a hydraulic cylinder assembly according to the present disclosure, and a lifting body engaged with the head supporting end portions of the inner piston and the outer piston.

[0016] According to another aspect, there is provided a method for lifting heavy machinery from a ground surface, comprising providing a lifting apparatus according to the present disclosure and injecting fluid from a fluid supply simultaneously into the innerfluid-receiving chamber and the outer fluid-receiving chamber of the piston-receiving cavity.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Fig. 1 is a top perspective view of a hydraulic cylinder assembly in accordance with an embodiment, the hydraulic cylinder assembly comprising inner and outer barrels coupled to each other, inner and outer pistons configured in a partially extended configuration and a casing assembly comprising a lower casing member;

[0018] Fig. 2 is a cross-section view of the hydraulic cylinder assembly of Fig. 1 , the hydraulic cylinder assembly further comprising a hydraulic locking device and the casing assembly further comprising an upper casing member, the inner and outer pistons being both configured in a retracted configuration;

[0019] Fig 3 is a cross-section view of the hydraulic cylinder assembly of Fig. 2, the inner and outer pistons being both configured in an extended configuration;

[0020] Fig. 4 is a top plan view of the hydraulic cylinder assembly of Fig. 1 ; [0021] Fig. 5 is a front elevation view of a lifting apparatus in accordance with an embodiment, the lifting apparatus comprising the hydraulic cylinder assembly of Fig. 1 ; and

[0022] Fig. 6 is a block diagram representing the sequential steps of a method for lifting a heavy machinery.

DETAILED DESCRIPTION

[0023] In the following description, the same numerical references refer to similar elements. Furthermore, for the sake of simplicity and clarity, namely so as to not unduly burden the figures with several references numbers, not all figures contain references to all the components and features, and references to some components and features may be found in only one figure, and components and features of the present disclosure which are illustrated in other figures can be easily inferred therefrom. The embodiments, geometrical configurations, materials mentioned and/or dimensions shown in the figures are optional, and are given for exemplification purposes only.

[0024] Moreover, it will be appreciated that positional descriptions such as "above", "below", "forward", "rearward", "left", "right" and the like should, unless otherwise indicated, be taken in the context of the figures only and should not be considered limiting. Moreover, the figures are meant to be illustrative of certain characteristics of the hydraulic cylinder assembly and are not necessarily to scale.

[0025] To provide a more concise description, some of the quantitative expressions given herein may be qualified with the term "about". It is understood that whether the term "about" is used explicitly or not, every quantity given herein is meant to refer to an actual given value, and it is also meant to refer to the approximation to such given value that would reasonably be inferred based on the ordinary skill in the art, including approximations due to the experimental and/or measurement conditions for such given value. [0026] In the following description, an embodiment is an example or implementation. The various appearances of "one embodiment", "an embodiment" or "some embodiments" do not necessarily all refer to the same embodiments. Although various features may be described in the context of a single embodiment, the features may also be provided separately or in any suitable combination. Conversely, although the invention may be described herein in the context of separate embodiments for clarity, it may also be implemented in a single embodiment. Reference in the specification to "some embodiments", "an embodiment", "one embodiment" or "other embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments.

[0027] It is to be understood that the phraseology and terminology employed herein is not to be construed as limiting and are for descriptive purpose only. The principles and uses of the teachings of the present disclosure may be better understood with reference to the accompanying description, figures and examples. It is to be understood that the details set forth herein do not construe a limitation to an application of the disclosure.

[0028] Furthermore, it is to be understood that the disclosure can be carried out or practiced in various ways and that the disclosure can be implemented in embodiments other than the ones outlined in the description above. It is to be understood that the terms "including", "comprising", and grammatical variants thereof do not preclude the addition of one or more components, features, steps, or integers or groups thereof and that the terms are to be construed as specifying components, features, steps or integers. If the specification or claims refer to "an additional" element, that does not preclude there being more than one of the additional element. It is to be understood that where the claims or specification refer to "a" or "an" element, such reference is not be construed that there is only one of that element. It is to be understood that where the specification states that a component, feature, structure, or characteristic "may", "might", "can" or "could" be included, that particular component, feature, structure, or characteristic is not required to be included. [0029] The descriptions, examples, methods and materials presented in the claims and the specification are not to be construed as limiting but rather as illustrative only. Meanings of technical and scientific terms used herein are to be commonly understood as by one of ordinary skill in the art to which the invention belongs, unless otherwise defined. It will be appreciated that the methods described herein may be performed in the described order, or in any suitable order.

[0030] Referring now to the drawings, and more particularly to Figs. 1 to 3, there is shown a hydraulic cylinder assembly 100 that is configured, for instance and without being limitative, to equip a lifting apparatus (Fig. 5) configured and designed to lift heavy machinery.

[0031] In the embodiment shown, the hydraulic cylinder assembly 100 has a longitudinal direction X1 (or longitudinal axis X1 ) and comprises an outer barrel 200 having an inner peripheral surface 202 defining a piston-receiving cavity 210 . The hydraulic cylinder assembly 100 further comprises an inner barrel 300 coupled (either directly or indirectly, as detailed below) to the outer barrel 200 and extending in the piston-receiving cavity 210. The inner barrel 300 has an outer peripheral surface 304 facing at least partially the inner peripheral surface 202 of the outer barrel 200, and an opposed inner peripheral surface 302. The inner barrel 300 separates the piston-receiving cavity 210 into an outer fluid receiving chamber 220 and an inner fluid-receiving chamber 230.

[0032] The hydraulic cylinder assembly 100 further comprises an outer piston 400 at least partially inserted in the outer fluid-receiving chamber 220 and comprising a sealing end portion 420 having a fluid-contacting surface 430. The sealing end portion 420 of the outer piston 400 sealingly contacts the inner peripheral surface 202 of the outer barrel 200 and the outer peripheral surface 304 of the inner barrel 300. The sealing end portion 420 is translatable within the outer fluid-receiving chamber 220 along the longitudinal axis X1. The sealing end portion 420 is thus translatable with respect to the inner barrel 300 and the outer barrel 200. The outer piston 400 thus at least partially extends between the outer barrel 200 and the inner barrel 300. In the following description, the term sealingly should be understood as meaning that a fluid-tight contact (or free of fluid leak) (for instance a liquid-tight contact) is provided between the contacted components.

[0033] The hydraulic cylinder assembly 100 further comprises an inner piston 500 at least partially inserted in the inner fluid-receiving chamber 230. The inner piston 500 comprises a sealing end portion 520 having a fluid-contacting surface 530. The sealing end portion 520 sealingly (i.e. in a fluid tight manner) contacts the inner peripheral surface 302 of the inner barrel 300 and is translatable within the inner fluid-receiving chamber 230 along the longitudinal axis Xl The sealing end portion 520 is thus translatable with respect to the inner barrel 300 and the outer barrel 200. As described in detail below, the hydraulic cylinder assembly 100 is configured so that, in use, the sealing end portion 520 of the inner piston 500 and the sealing end portion 420 of the outer piston 400 are translatable substantially simultaneously within the corresponding one of the inner and outer fluid-receiving chambers 230, 220. In other words, the hydraulic cylinder assembly 100 is configured so that the sealing end portions 520, 420 of the inner and outer pistons 500, 400 undergo substantially coincident displacements along the longitudinal direction X1 in the corresponding one of the inner and outer fluid receiving chambers 230, 220.

Outer barrel

[0034] In the embodiment shown, the outer barrel 200 has a substantially cylindrical shape and extends along the longitudinal axis X1 of the hydraulic cylinder assembly 100.

[0035] The inner peripheral surface 202 of the outer barrel 200 outwardly delimits radially (i.e. in a direction transversal, for instance substantially perpendicular, to the longitudinal direction X1 ) the piston-receiving cavity 210. The outer barrel 200 comprises an opposed outer peripheral surface 204. The outer barrel 200 comprises a lower end portion 206 and an opposed open upper end portion 208, both considered along the longitudinal direction X1. In the embodiment shown, a bottom cap 600 (for instance a fluid supply cap 600 in the embodiment shown) of the hydraulic cylinder assembly 100 is engaged with (for instance mounted to or coupled to) the lower end portion 206 of the outer barrel 200 in order to close the piston-receiving cavity 210 of the outer barrel 200 at the lower end portion 206 thereof.

[0036] In the embodiment show, the bottom cap 600 comprises a bottom wall portion 602 extending transversally (for instance substantially perpendicularly) to the longitudinal direction X1 and an outer peripheral wall portion 604 having for instance a substantially cylindrical shape and extending upwardly from the bottom wall portion 602 along the longitudinal axis X1. In other words, the outer peripheral wall portion 604 is substantially coaxial with the outer barrel 200. The bottom cap 600 further comprises an inner peripheral wall portion 606 having for instance a substantially cylindrical shape and extending upwardly from the bottom wall portion 602 along the longitudinal direction X1. The inner peripheral wall portion 606 is spaced apart from the outer peripheral wall portion 604 so as to define therewith an outer barrel-receiving slot 608. In the embodiment shown, the outer barrel-receiving slot 608 is shaped and dimensioned to receive at least partially the outer barrel 200 (at least a portion of the lower end portion 206 thereof, in the embodiment shown).

[0037] It is appreciated that the shape and the configuration of the outer barrel 200, as well as the shape, the configuration and the location of the bottom cap 600 can vary from the embodiment shown.

Inner barrel

[0038] The inner barrel 300 has a substantially cylindrical shape and extends coaxially within the outer barrel 200 (i.e. extending along the longitudinal direction X1 ).

[0039] The inner peripheral surface 302 of the inner barrel 300 outwardly delimits radially the inner fluid-receiving chamber 230. In the non-limitative embodiment shown, the inner fluid-receiving chamber 230 is thus substantially cylindrical and extends along the longitudinal axis X1.

[0040] In the embodiment shown, the outer fluid-receiving chamber 220 is outwardly radially delimited - considered in an outward direction with regards to the inner fluid-receiving chamber 230 - by the inner peripheral surface 202 of the outer barrel 200. The outer fluid-receiving chamber 220 is further internally radially delimited - considered in an inward direction with regards to the inner fluid-receiving chamber 230 - by the outer peripheral surface 304 of the inner barrel 300. Thus, in the non-limitative embodiment shown, the outer fluid receiving chamber 220 is substantially tubular in shape and extends along the longitudinal direction X1 . Considered along the longitudinal direction X1 , the inner fluid-receiving chamber 230 is delimited by the fluid-contacting surface 530 of the sealing end portion 520 of the inner piston 500 and the bottom cap 600, in the embodiment shown (or by a bottom portion of the inner barrel 300, in another embodiment - not represented).

[0041] The inner barrel 300 comprises a lower end portion 306 to which the fluid supply cap 600 (or bottom cap 600) is secured to close the inner barrel 300 at the lower end portion 306. For instance, the lower end portion 306 is mounted to (or engaged with) the inner peripheral wall portion 606 of the bottom cap 600 (for instance to an inner peripheral surface thereof).

[0042] In the embodiment shown, an inner fluid supply conduit 610 extends at least partially in the fluid supply cap 600 (or bottom cap 600) - for instance in the bottom wall portion 602 thereof - to fluidly connect the inner fluid-receiving chamber 230 to a fluid supply 630. An outer fluid supply conduit 620 at least partially extends in the fluid supply cap 600 - for instance in the bottom wall portion 602 thereof - to fluidly connect the outer fluid-receiving chamber 220 to the fluid supply 630. In the embodiment shown, as represented in Figs. 2 and 3, the inner fluid-receiving chamber 230 and the outer fluid-receiving chamber 220 are both fluidly connected - via the corresponding one of the inner fluid supply conduit 610 and the outer fluid supply conduit 620 - to a single fluid supply. It could also be conceived an embodiment wherein the inner fluid-receiving chamber and the outer fluid-receiving chamber would be fluidly connected respectively to distinct inner and outer fluid sources (or inner and outer fluid supplies). [0043] The inner barrel 300 further comprises an opposed open upper end portion 308.

[0044] It is appreciated that the shape, the configuration, and the location of the inner barrel 300 can vary from the embodiment shown.

Inner piston

[0045] In the embodiment shown, the inner piston 500 comprises a body 510 - or inner piston rod 510 - extending along the longitudinal direction X1 and having a substantially cylindrical shape (i.e. a substantially circular cross-section). The inner piston rod 510 has a rod body 511 mounted to the sealing end portion 520 and extending from a rod-facing surface 531 of the sealing end portion 520, the rod-facing surface 531 being opposed to the fluid-contacting surface 530 of the sealing end portion 520. An outer diameter d1 of the rod body 51 1 of the inner piston rod 510, as represented in Fig. 2, is smaller than an inner diameter d2 of the inner fluid-receiving chamber 230 so that the rod body 51 1 of the inner piston rod 510 is receivable into the inner fluid-receiving chamber 230 and translatable therein along the longitudinal direction X1.

[0046] As mentioned above, the sealing end portion 520 (or lower end portion 520) of the inner piston 500 sealingly contacts (i.e. forms a fluid tight contact with) the inner peripheral surface 302 of the inner barrel 300. In other words, the sealing end portion 520 is shaped and dimensioned to prevent the inner fluid contained in the inner fluid-receiving chamber 230 and provided therein by the fluid supply 630 via the inner fluid supply conduit 610 to flow outwardly therefrom either through the sealing end portion 520 of the inner piston 500 or through a contact area 521 (Fig. 2) between the sealing end portion 520 and the inner peripheral surface 302 of the inner barrel 300. The sealing end portion 520 is also configured to prevent the inner fluid contained in the inner fluid-receiving chamber 230 to flow outwardly therefrom through the inner barrel 300 or via the upper end portion 308 of the inner barrel 300. The sealing end portion 520 of the inner piston 500 has thus an outer diameter corresponding substantially to the inner diameter d2 of the inner fluid-receiving chamber 230. [0047] In the embodiment shown, the sealing end portion 520 of the inner piston 500 has a substantially cylindrical shape extending along the longitudinal direction X1 and comprises an outer peripheral surface 522 to which is mounted an inner seal 524 (for instance substantially annular in shape) circumscribing peripherally a peripheral wall of the sealing end portion 520 of the inner piston 500.

[0048] The fluid-contacting surface 530 of the sealing end portion 520 has a surface area. In the embodiment shown, the sealing end portion 520 of the inner piston 500 comprises a central portion 526 substantially cylindrical and formed by a sealing end-mounting portion 513 (or lower end portion 513) of the inner piston rod 510. The sealing end portion 520 of the inner piston 500 further comprises a sealing body 528 - or peripheral sealing portion 528 - having a substantially annular shape. The peripheral sealing end portion 528 is coaxial with the inner and outer barrels 300, 200. A rod-receiving opening 529 is formed in the peripheral sealing portion 528 that is shaped and dimensioned to receive at least partially the sealing end-mounting portion 513 of the inner piston rod 510. In other words, the peripheral sealing portion 528 surrounds peripherally the central portion 526 formed by at least a portion of the sealing end-mounting portion 513 of the inner piston rod 510. In the embodiment shown, the sealing body 528 - or peripheral sealing portion 528 - is slightly axially (longitudinally) offset with regards to the central portion 526 (in an upward direction, in the embodiment shown) so that the fluid-contacting surface 530 comprises a central surface (substantially circular in the embodiment shown) formed by the central portion 526 and a peripheral surface (substantially annular, in the embodiment shown) formed by the peripheral sealing portion 528. The peripheral surface and the central surface of the fluid-contacting surface 530 of the sealing end portion 520 of the inner piston 500 are substantially parallel to each other and slightly offset along the longitudinal direction X1.

[0049] The inner piston rod 510 of the inner piston 500 further comprises a head supporting end portion 540 (or upper end portion 540) that is for instance substantially cylindrical and coaxial with the outer and inner barrels 200, 300. In the embodiment shown, the head-supporting end portion 540 has a head- connecting aperture 542 formed therein (for instance substantially centrally therein).

[0050] It is appreciated that the shape and the configuration of the inner piston 500, and more particularly the shape, the configuration and the location of the sealing end portion 520 and the inner piston rod 510 comprising the head supporting end portion 540, the rod body 51 1 and the sealing end-mounting portion 513 can vary from the embodiment shown. For instance, it could be conceived a sealing end portion of the inner piston 500 that would be formed of a single component.

Outer piston

[0051] In the embodiment shown, the outer piston 400 is coaxial with the inner piston 500 and with the outer and inner barrels 200, 300. The outer piston 400 extends at least partially between the inner barrel 300 and the outer barrel 200. In the embodiment shown, the outer piston 400 comprises a body 410 - or outer piston rod 410 - extending along the longitudinal direction X1 and having a substantially tubular cross-section. An inner diameter d3 of the tubular body 410 - or outer piston rod 410 - is greater than an outer diameter d4 of the inner barrel 300, whereas an outer diameter d5 of the tubular body 410 is smaller than an inner diameter d6 of the outer barrel 200. The tubular body 410 - or outer piston rod 410 - of the outer piston 400 is thus at least partially receivable into the outer fluid-receiving chamber 220 and translatable between the inner and outer barrels 300, 200 along the longitudinal direction X1 (i.e. translatable within the outer fluid receiving chamber 220). The sealing end portion 420 of the outer piston 400 has a rod-facing surface 431 opposed to the fluid-contacting surface 430 and the outer piston rod 410 comprises a rod body 41 1 mounted to the sealing end portion 420 and extending upwardly from the rod-facing surface 431.

[0052] As mentioned above, the sealing end portion 420 (or lower end portion 420) of the outer piston 400 sealingly contacts (i.e. in a fluid tight manner) the inner peripheral surface 202 of the outer barrel 200 and the outer peripheral surface 304 of the inner barrel 300 so as to prevent the outer fluid contained in the outer fluid-receiving chamber 220 and provided therein by the fluid supply 630 the via the outer fluid supply conduit 620 to flow outwardly therefrom through the upper end portion 208 of the outer barrel 200. In other words, the sealing end portion 420 is shaped and dimensioned to form a fluid tight contact between the outer piston 400 and, in an outward direction considered with respect to the outer fluid-receiving chamber 220, a contact area 421 (Fig. 3) between the sealing end portion 420 of the outer piston 400 and the inner peripheral surface 202 of the outer barrel 200 and, in an inward direction considered with respect to the outer fluid-receiving chamber 220, a contact 425 area (Fig. 3) between the sealing end portion 420 of the outer piston 400 and the outer peripheral surface 304 of the inner barrel 300. The sealing end portion 420 is thus configured to prevent the outer fluid of the outer fluid-receiving chamber 220 from flowing outwardly therefrom through the upper end portion 208 of the outer barrel 200.

[0053] In the embodiment shown, the sealing end portion 420 of the outer piston 400 is substantially annular in shape and has an outer diameter corresponding substantially to the inner diameter d6 of the outer barrel 200 (i.e. to the inner diameter of the piston-receiving cavity 210), and an inner diameter corresponding substantially to the outer diameter d4 of the inner barrel 300.

[0054] In the embodiment shown, the sealing end portion 420 of the outer piston 400 comprises a lower sealing portion 422 having a substantially tubular shape extending along the longitudinal direction X1 , and an upper sealing portion 424 (or outer piston rod-mounting portion 424) with which a sealing end-mounting portion 413 of the outer piston rod 410 is engaged. In the embodiment shown, the upper sealing portion 424 of the sealing end portion 420 extends between the sealing-end mounting portion 413 of the outer piston rod 410 and the outer barrel 200. The lower sealing portion 422 of the sealing end portion 420 comprises outer and inner peripheral surfaces to which outer and inner seals 426, 428 are respectively mounted (for instance the outer and inner seals 426, 428 are substantially annular in shape). In other words, a rod-receiving opening 423 is formed in the sealing end portion 420 of the outer piston 400 that is shaped and dimensioned to receive the sealing end-mounting portion 413 of the outer piston rod 410. [0055] The fluid-contacting surface 430 of the sealing end portion 420 has a surface area. In the embodiment shown, the fluid contacting surface 430 of the sealing end portion 420 is substantially annular in shape. In the embodiment shown, the surface area of the fluid-contacting surface 430 of the sealing end portion 420 is substantially equal to the surface area of the fluid-contacting surface 530 of the sealing end portion 520 of the inner piston 500. In some embodiments, the surface area of the fluid-contacting surface 430 of the sealing end portion 420 of the outer piston 400 is equal to or greater than about 85% of the surface area of the fluid-contacting surface 530 of the sealing end portion 520 of the inner piston 500. In some other embodiments, the surface area of the fluid contacting surface 430 of the sealing end portion 420 is equal to or greater than about 90% of the surface area of the fluid-contacting surface 530 of the sealing end portion 520. In some other embodiments, the surface area of the fluid contacting surface 430 of the sealing end portion 420 is equal to or greater than about 95% of the surface area of the fluid-contacting surface 530 of the sealing end portion 520. In yet some other embodiments, the surface area of the fluid contacting surface 430 of the sealing end portion 420 is equal to or greater than about 97% of the surface area of the fluid-contacting surface 530 of the sealing end portion 520. In some embodiments, the surface area of the fluid-contacting surface 530 of the sealing end portion 520 of the inner piston 500 is equal to or greater than about 85% of the surface area of the fluid-contacting surface 430 of the sealing end portion 420 of the outer piston 400. In some other embodiments, the surface area of the fluid-contacting surface 530 of the sealing end portion 520 is equal to or greater than about 90% of the surface area of the fluid-contacting surface 430 of the sealing end portion 420. In some other embodiments, the surface area of the fluid-contacting surface 530 of the sealing end portion 520 is equal to or greater than about 95% of the surface area of the fluid-contacting surface 430 of the sealing end portion 420. In yet some other embodiments, the surface area of the fluid-contacting surface 530 of the sealing end portion 520 is equal to or greater than about 97% of the surface area of the fluid-contacting surface 430 of the sealing end portion 420. [0056] The outer piston rod 410 of the outer piston 400 further comprises a head supporting end portion 440 (or upper end portion 440). In the embodiment shown, a head-receiving indentation 442 is formed in the head-supporting end portion 440.

[0057] It is appreciated that the shape and the configuration of the outer piston 400, and more particularly the shape, the configuration and the location of the sealing end portion 420 and the outer piston rod 410 comprising the head supporting end portion 440, the rod body 41 1 and the sealing end-mounting portion 413 can vary from the embodiment shown. It could also be conceived, similarly to the inner barrel, an outer barrel wherein the sealing end portion 420 would be formed at least partially by a portion of the outer piston rod 410.

[0058] Moreover, even though in the embodiment shown, the bottom cap 600 is formed of a single element having portions with which both the outer barrel 200 and the inner barrel 300 are engaged, it could also be conceived a hydraulic cylinder assembly having distinct bottom caps. It could also be conceived a hydraulic cylinder assembly wherein the inner barrel would be engaged directly with a bottom wall portion of the outer barrel - and not via a bottom cap, as in the embodiment shown. It could also be conceived inner and outer barrels that would be formed of two components of a single element.

Cooperation of the inner and outer pistons

[0059] The hydraulic cylinder assembly 100 further comprises a cylinder connecting head 650 connecting together the inner and outer pistons 500, 400, via, in the embodiment shown, their respective head-supporting end portions 540, 440.

[0060] In the embodiment shown, and as represented for instance in Figs. 3 and 4, the cylinder-connecting head 650 comprises a central portion 652 (substantially circular, for instance) with a central opening 653 formed therein in register with the head connecting aperture 542 of the head-supporting end portion 540 of the inner piston 500 when engaged therewith. The hydraulic cylinder assembly 100 further comprises a rivet 660 (or any other suitable mechanical fastener such as a screw) to secure the cylinder connecting head 650 to the head supporting end portion 540 of the inner piston 500.

[0061] The cylinder-connecting head 650 further comprises a peripheral portion 654 (for instance having a substantially annular shape, in the embodiment shown) with a peripheral wall portion 656 extending from a lower surface downwardly thereof. The peripheral wall portion 656 is engageable with the head-supporting end portion 440 of the outer piston 400 (for instance with an inner peripheral surface of the head supporting end portion 440 and having a portion thereof insertable in the head-receiving indentation 442 formed in the head-supporting end portion 440).

[0062] In the embodiment shown, as represented in Fig. 3, an upper chamber 240 is defined, in a radial direction (i.e. in a direction perpendicular to the first longitudinal axis X1 ), between an inner peripheral surface 414 of the outer piston rod 410 and an outer peripheral surface 512 of the inner piston rod 510, and, in the longitudinal direction X1 , between the rod-facing surfaces of the sealing end portions 520, 420 of the inner and outer pistons 500, 400 and the cylinder connecting head 650. In the embodiment shown, a through opening 662 - orfluid circulation opening 662 - is formed in the cylinder-connecting head 650 to fluidly connect the upper chamber 240 to an external environment. It is understood that a volume of the upper chamber 240, when the outer and inner pistons 400, 500 are configured in an extended configuration, as represented in Fig. 3, is greater than the volume of the upper chamber 240 when the outer and inner pistons 400, 500 are configured in a retracted configuration, as represented in Fig. 2. In particular, when the outer and inner pistons 400, 500 are in the retracted configuration, as represented in Fig. 2, the inner barrel 300 extends in the upper chamber 240 and separates the upper chamber 240 in a non-sealingly manner - i.e. in a non-fluid-tight manner - into an outer upper chamber 242 and an inner upper chamber 244. The through opening 662 - or fluid circulation opening 662 - is thus dimensioned for gas or any other fluid to entry into the upper chamber 240 when the volume of the upper chamber 240 is increasing (i.e. when the inner and outer pistons 500, 400 are translated within the corresponding one of the inner and outer fluid-receiving chambers 220, 230 to be configured from the retracted configuration into the extended configuration).

[0063] In the embodiment shown, at least one seal 541 (for instance substantially annular in shape) is engaged with an upper surface of the head-supporting end portion 540 to prevent a fluid contained in the upper chamber 240 from flowing outwardly therefrom through the head-connecting aperture 542 formed in the head-supporting end portion 540.

[0064] The hydraulic cylinder assembly 100 further comprises an inner piston- guiding sleeve 670, as represented in Figs. 2 and 3, provided at and mounted to the upper end portion 308 of the inner barrel 300. An inner piston-guiding cavity 672 is formed in the inner piston-guiding sleeve 670 that is substantially cylindrical in shape, in the embodiment shown, and that is shaped and dimensioned to substantially conform to the inner piston 500, and more particularly to the inner piston rod 510 of the inner piston 500. The inner piston- guiding sleeve 670 at least partially surrounds the inner piston rod 510 (for instance the rod body 51 1 thereof) of the inner piston 500. The inner piston rod 510 of the inner piston 500 is translatable in the inner piston-guiding cavity 672 when the sealing end portion 520 of the inner piston 500 is translated within the inner fluid-receiving chamber 230 for the inner piston 500 to be configured from one of the extended and retracted configurations into the other.

[0065] A fluid conduit 674 is formed in the inner piston-guiding sleeve 670 that extends therethrough between opposed surfaces considered along the longitudinal direction X1 (i.e. between opposed upper and lower surfaces of the inner piston-guiding sleeve). The inner piston-guiding sleeve 670 is dimensioned to be axially (with regards to the longitudinal direction X1 ) offset with regards to the cylinder-connecting head 650 when the inner piston 500 is in the retracted configuration. When the inner and outer pistons 500, 400 are configured in the retracted configuration, the outer and inner upper chambers 242, 244 of the upper chamber 240 are thus in fluid communication with each other. Moreover, the outer and inner cavities 242, 244 - or outer and inner upper chambers 242, 244 - are in fluid communication with the through opening 662 (or fluid conduit 662, or fluid circulation opening 662) formed in the cylinder-connecting head 650.

[0066] As represented in Fig. 2, it is thus understood that the sealing end portion 520 of the inner piston 500 sealingly separates - considered along the longitudinal direction X1 - the inner fluid-receiving chamber 230 from the inner upper chamber 244, whereas the sealing end portion 420 of the outer piston 400 sealingly separates - considered along the longitudinal direction X1 - the outer fluid-receiving chamber 220 from the outer upper chamber 242.

[0067] Considered along the longitudinal direction X1 , the inner upper chamber 244 is upwardly delimited - in a non-sealingly manner, in the embodiment shown

- by the inner piston-guiding sleeve 670 and is downwardly delimited by the rod facing surface 531 of the sealing end portion 520 of the inner piston 500.

[0068] Considered along the longitudinal direction X1 , the outer upper chamber 242 is upwardly delimited - in a non-sealingly manner, in the embodiment shown

- by the cylinder-connecting head 650 and is downwardly delimited by the rod facing surface 431 of the sealing end portion 420 of the outer piston 400.

[0069] In yet other words, the sealing end portion 520 of the inner piston 500 is translatable in the inner fluid-receiving chamber 230 between the fluid supply cap 600 - or bottom cap 600 - and the inner piston-guiding sleeve 670 for the inner piston 500 to be configured from one of the extended and retracted configurations into the other.

[0070] The hydraulic cylinder assembly 100 further comprises an outer piston- guiding sleeve 680 provided at the upper end portion 208 of the outer barrel 200 and sealingly surrounding the outer piston rod 410 of the outer piston 400 (for instance the rod body 41 1 thereof). An outer piston-guiding cavity 682 is formed in the outer piston-guiding sleeve 680 that is substantially cylindrical in shape, in the embodiment shown, and that substantially conforms to the outer piston 400, and more particularly to the rod body 411 of the outer piston rod 410. The outer piston-guiding sleeve 680 at least partially surrounds an outer peripheral surface 412 of the outer piston rod 410. The rod body 41 1 of the outer piston rod 410 is translatable into the outer piston-guiding cavity 682 when the outer piston 400 is configured from one of the extended and retracted configurations to the other upon translation of the sealing end portion 420 of the outer piston 400 within the outer fluid-receiving chamber 220. A seal 683 is engaged with an inner peripheral surface of the outer piston guiding sleeve 680 to sealingly surround the outer piston rod 410 of the outer piston 400 when translated therein.

[0071] The sealing end portion 420 of the outer piston 400 is thus translatable in the outer fluid-receiving chamber 220 between the fluid supply cap 600 - or bottom cap 600 - and the outer piston-guiding sleeve 680 for the outer piston 400 to be configured from one of the extended and retracted configurations into the other one.

[0072] As represented in Fig. 2, an upper fluid-receiving chamber 250 - or feedback fluid-receiving chamber 250 - is delimited - considered in a radial direction - by the inner peripheral surface 202 of the outer barrel 200 and the outer peripheral wall surface 412 of the outer piston rod 410 of the outer piston 400. In other words, when the outer piston 400 is configured in the retracted configuration, the outer piston rod 410 of the outer piston 400 separates the upper fluid-receiving chamber 250 - or feedback fluid-receiving chamber 250 - and the outer upper chamber 242. In the embodiment shown, a feedback fluid conduit 684 is formed in the outer piston-guiding sleeve 680 that is fluidly connected to the feedback fluid-receiving chamber 250. A first volume of the feedback fluid receiving chamber 250 when the inner and outer pistons 500, 400 are configured in the retracted configuration is greater than a second volume of the feedback fluid-receiving chamber 250 when the inner and outer pistons 500, 400 are configured in the extended configuration. In the embodiment shown in which the rod-facing surface 431 of the sealing end portion 420 of the outer piston 400 is close to - or even contacts - a lower surface of the outer piston-guiding sleeve 680 when the inner and outer pistons 500, 400 are configured in the extended configuration, the first volume of the feedback fluid-receiving chamber 250 is slightly null when the inner and outer pistons 500, 400 are configured in the extended configuration. [0073] It is appreciated that the shape, the configuration, and the location of cylinder-connecting head 650, the inner piston-guiding sleeve 670 and the outer piston-guiding sleeve 680 can vary from the embodiment shown. It could also be conceived a hydraulic cylinder assembly wherein the inner piston-guiding sleeve and/or the outer piston-guiding sleeve would be formed integral with the corresponding one of the inner and outer barrels. It could also be conceived a hydraulic cylinder assembly wherein the cylinder-connecting head would be formed integral with at least a portion of the inner and/or outer pistons (for instance integral with the head-supporting end portion thereof).

Casing assembly

[0074] In the embodiment shown, the hydraulic cylinder assembly 100 further comprises a casing assembly 700 designed to at least partially contain the inner and outer pistons 500, 400 and the outer and inner barrels 200, 300. The casing assembly 700 is coaxial with the inner and outer barrels 300, 200.

[0075] For instance, the casing assembly 700 comprises a telescopic casing system 702 comprising a lower casing member 710 surrounding the outer barrel 200 (i.e. the casing assembly 700 is telescopic). In the embodiment shown, the lower casing member 710 has a substantially cylindrical shape and extends along the longitudinal direction X1. The lower casing member 710 is fixedly secured to the bottom cap 600 (for instance to the outer peripheral wall portion 604 thereof) and extends upwardly therefrom. In the embodiment shown, as represented in Fig. 2, an inner diameter d7 of the lower casing member 710 is greater than an outer diameter d8 of the outer barrel 200 so that a peripheral cavity 712 (Fig. 3) is formed between the lower casing member 710 and the outer barrel 200. In the embodiment shown, the peripheral cavity 712 is substantially tubular in shape.

[0076] The telescopic casing system 702 of the casing assembly 700 further comprises an upper casing member 720 mechanically coupled to the inner and outer pistons 500, 400 and translatable with respect to the inner barrel 300 and the outer barrel 200 along the longitudinal direction X1 . In the embodiment shown, the upper casing member 720 has a substantially cylindrical shape and extends along the longitudinal direction X1. The upper casing member 720 is coaxial with the inner and outer barrels 300, 200. For instance and without being limitative, the upper casing member 720 has an upper portion 722 mechanically coupled to the cylinder-connecting head 650 (for instance secured to the peripheral portion 654 of the cylinder-connecting head 650) for the inner and outer pistons 500, 400 and the upper casing member 720 to be translatable together along the longitudinal direction X1 upon actuation of the hydraulic cylinder assembly (i.e. upon injection of fluids into the inner fluid-receiving chamber, the outer fluid-receiving chamber and/or the feedback fluid-receiving chamber).

[0077] In the embodiment shown, an inner diameter of the upper casing member 720 is slightly greater than an outer diameter of the lower casing member 710 for the upper casing member 720 to be slidable along the longitudinal direction X1 outwardly with regards to the lower casing member 710.

[0078] In the embodiment shown, the casing assembly 700 further comprises an upper casing member-guiding sleeve 730 mounted for instance to an upper end portion of the lower casing member 710 and/or to the upper end portion 208 of the outer barrel 200 and surrounding at least partially the outer piston-guiding sleeve 680. The upper casing member 720 is slidable outwardly with regards to the upper casing member-guiding sleeve 730. In the embodiment shown, the upper casing member-guiding sleeve 730 is engaged with the upper end portion 208 of the outer barrel 200 (for instance via a thread formed on an inner surface of the upper casing member-guiding sleeve 730 designed to cooperate with a complementary thread formed on an outer surface of the upper end portion 208 of the outer barrel 200, or via any other suitable mechanical fastener). Thus, when the different components of the casing assembly 700 are assembled together to at least partially contain the inner and outer pistons 500, 400 and the outer and inner barrels 200, 300, the lower casing member 710 is maintained, considered in a direction parallel to the longitudinal direction X1 , between the fluid supply cap 600 - or bottom cap - and the upper casing member-guiding sleeve 730. Moreover, the upper casing member-guiding sleeve 730 contributes to the radial stability (i.e. in a direction substantially perpendicular to the longitudinal direction X1 ) of the different components of the hydraulic cylinder assembly 100. The radial stability is also ensured by radial abutting surfaces formed, on the one hand, between the head supporting-end portions 440, 540 of the outer and inner pistons 400, 500 and the cylinder-connecting head 650 and, on the other hand, between the sealing end portion 520 of the inner piston 500 and the inner piston-guiding sleeve 670 engaged with the upper end portion 308 of the inner barrel 300.

[0079] It is appreciated that the shape and the configuration of the casing assembly 700, and more particularly the shape, the configuration and the location of the upper casing member 720, the lower casing member 710 and the upper casing member-guiding sleeve 730, as well as the number of the members forming the telescopic casing system can vary from the embodiment shown.

Hydraulic locking device

[0080] As represented in Figs. 2 and 3, the hydraulic cylinder assembly 100 further comprises a hydraulic locking device 800. The hydraulic locking device 800 in this embodiment comprises an inner piston load-locking valve 810 (or inner piston counterbalance valve 810) and an outer piston load-locking valve 820 (or outer piston counterbalance valve 820) operatively connected respectively to the inner fluid supply conduit 610 and the outer fluid supply conduit 620. The inner and outer piston load-locking valves 810, 820, or holding valves, or counterbalance valves, offer a substantially high level of hydraulic safety protection, as detailed below. Even though in the embodiment shown, the inner and outer piston load-locking valves 810, 820 are mounted to the inner fluid supply conduit 610 and the outer fluid supply conduit 620 at a distance from the fluid supply cap 600 (or bottom cap 600) (outwardly from the hydraulic cylinder assembly 100), it could also be conceived a hydraulic cylinder assembly in which the inner and outer piston load-locking valves would be mounted in the portions of the inner fluid supply conduit 610 and the outer fluid supply conduit extending in the fluid supply cap 600.

Method for configuring the inner and outer pistons into the extended configuration

[0081] The present disclosure also concerns a method for configuring the inner and outer pistons 500, 400 into the extended configuration. [0082] The method for configuring the inner and outer pistons 500, 400 into the extended configuration, when the inner and outer pistons 500, 400 are initially in the retracted configuration, as represented in Fig. 2, comprises injecting outer and inner fluids simultaneously respectively into the outer fluid-receiving chamber 220 and the inner fluid-receiving chamber 230 respectively via the outer fluid supply conduit 620 and the inner fluid supply conduit 610. In the embodiment shown, the inner fluid-receiving chamber 230 and the outer fluid-receiving chamber 220 are both fluidly connected to the same fluid supply 630 (i.e. the inner and outer fluids are provided respectively to the inner and outer fluid receiving chambers via a single fluid supply) so that a fluid with an identical pressure is provided thereto. It could however be conceived a hydraulic cylinder assembly in which the inner fluid-receiving chamber and the outer fluid-receiving chamber would be fluidly connected to different fluid supplies. In this embodiment (not represented), the method for configuring the inner and outer pistons into the extended configuration would comprise injecting an inner fluid with an inner fluid pressure into the inner fluid-receiving chamber, and injecting simultaneously an outer fluid with an outer fluid pressure into the outer fluid-receiving chamber, the outer fluid pressure being substantially identical to the inner fluid pressure. The hydraulic cylinder assembly could thus further comprise, in this embodiment, a fluid supply controller operatively coupled with the inner fluid supply conduit and the outer fluid supply conduit to ensure that fluids having a substantially identical fluid pressure are injected substantially simultaneously into the inner and outer fluid-receiving chambers of the hydraulic cylinder assembly.

[0083] As detailed above, in an embodiment, since the surface area of the inner fluid-contacting surface 530 (comprising in the embodiment shown the central surface of the central portion 526 and the peripheral surface of the peripheral sealing portion 528) is substantially equal to the surface area of the fluid contacting surface 430 of the sealing end portion 420 of the outer piston 400 and a same fluid pressure is applied to the fluid-contacting surfaces 530, 430, the sealing end portions 520, 420 of the inner and outer pistons 500, 400 are translated upwardly along the longitudinal direction X1 respectively in the inner fluid-receiving chamber 230 and in the outer fluid-receiving chamber 220 in a substantially simultaneous manner, so that the inner piston rod 510 and the outer piston rod 410 are translated along the longitudinal direction X1 is a substantially simultaneous manner.

[0084] The translation of the sealing end portions 520, 420 of the inner and outer pistons 500, 400 respectively in the inner fluid-receiving chamber 230 and in the outer fluid-receiving chamber 220 causes the raising of the head-supporting end portions 540, 440 of the inner and outer pistons 500, 400, and thus the raising of the cylinder-connecting head 650 secured thereto.

[0085] As represented in Fig. 5, there is disclosed a lifting apparatus 50 for lifting heavy machinery. The lifting apparatus 50 comprises a hydraulic cylinder assembly 100 and a lifting body 60 engaged with the inner and outer pistons 500, 400. In the embodiment shown, the cylinder-connecting head 650 has a lifting surface 658 extending in a plane substantially perpendicular to the longitudinal direction X1. The lifting body 60 is engaged with the lifting surface 658 of the cylinder-connecting head 650. It is thus understood that, when the inner and outer pistons 500, 400 are initially configured in the retracted configuration, the simultaneous translation of the sealing end portions 520, 420 of the inner and outer pistons 500, 400 respectively in the inner fluid-receiving chamber 230 and in the outer fluid-receiving chamber 220 ensures that the lifting surface 658 is kept substantially perpendicular to the longitudinal direction X1 when the cylinder connecting head 650 is raised (i.e. translated upwardly along the longitudinal direction X1 ). Thus, in the embodiment in which the lifting apparatus 50 comprises the hydraulic cylinder assembly 100 and the lifting body 60, and in which a machinery (or any other element) to be lifted is at least partially supported by the cylinder-connecting head 650 via the lifting body 60, the simultaneous deployment of the inner and outer pistons 500, 400 (i.e. the simultaneous translation in an upward direction along the longitudinal axis X1 of the sealing end portions 520, 420 of the inner and outer pistons 500, 400 respectively in the inner fluid-receiving chamber 230 and the outer fluid-receiving chamber 220) ensures a safe and stable lifting of the heavy machinery. In other words, in the disclosed hydraulic cylinder assembly 100, the substantially synchronous deployment of the inner and outer pistons 500, 400 is ensured, amongst others, by the single fluid supply 630 which supplies to both the outer fluid-receiving chamber 220 and the inner fluid-receiving chamber 230 (or by distinct inner and outer fluid supplies supplying respectively inner and outer fluids at substantially identical fluid pressures to the inner and outer fluid-receiving chambers), by the fact that the surface area of the fluid-contacting surface 530 of the sealing end portion 520 of the inner piston 500 is substantially equal to the surface area of the fluid contacting surface 430 of the sealing end portion 420 of the outer piston 400 and by the cylinder-connecting head 650 connecting together the head supporting end portions 540, 440 of the inner and outer pistons 500, 400.

[0086] The hydraulic locking device 800 further comprises a locking valve controller 830 cooperating with at least one of the load-locking valves 810, 820 of the hydraulic locking device 800 (with both in the embodiment shown) so as to shut off (i.e. close the respective one of the inner fluid supply conduit 610 and the outer fluid supply conduit 620) in case a hydraulic leakage (or fluid leakage) or failure with the inner and outer pistons 500, 400 is detected by the locking valve controller 830, thereby ensuring that the corresponding one of the inner and outer fluids (such as, for instance, oil) remains trapped inside the inner fluid-receiving chamber 230 and/or the outer fluid-receiving chamber 220 to maintain the inner and outer pistons 500, 400 in their extended configuration or in any other intermediate configuration between the extended configuration and the retracted configuration at the moment of the detection of the leakage or failure). The load locking valves 810, 820 therefore help to safely support the load of the lifted heavy machinery while the leakage or failure gets fixed. It will be appreciated that the unit of lifting force outputted by each of the inner and outer pistons 500, 400 can include tons/tonnes, psi/Pa, Ibs/N, etc.

[0087] In the embodiment shown, as mentioned above, the upper chamber 240 is fluidly connected via the through opening 662 - or fluid circulation opening 662 - formed, for instance, in the cylinder-connecting head 650, to an external environment surrounding the hydraulic cylinder assembly 100. In case one of the inner and outer pistons 500, 400 would break or dysfunction - for instance in case the inner fluid contained in the inner fluid-receiving chamber 230 would not be prevented from flowing outwardly therefrom, for instance through the sealing end portion 520 of the inner piston 500, or between the sealing end portion 520 and the inner peripheral surface 302 of the inner barrel 300 or in case the outer fluid contained in the outer fluid-receiving chamber 220 would not be prevented from flowing outwardly therefrom through the sealing end portion 420 of the outer piston 400, or between the sealing end portion 420 and the outer peripheral surface 304 of the inner barrel 300 and/or the inner peripheral surface 202 of the outer barrel 200, or for any other reason - so that at least one of the inner and outer fluids would entry the upper chamber 240, the breaking would thus be easily and visibly detectable since the inner and/or outer fluids would reach the outside of the hydraulic cylinder assembly 100. Moreover, the hydraulic cylinder assembly 100 is configured so that even if one of the inner and outer pistons 500, 400 breaks, the lifting and the support of the machinery by the lifting apparatus 50 will still be ensured by the other one of the inner and outer pistons 500, 400, thus providing a mechanical redundancy to the hydraulic cylinder assembly 100.

Method for lifting a heavy machinery

[0088] The present disclosure thus also concerns a method 900 for lifting heavy machinery from a ground surface. As represented in Fig. 6, the method comprises a step 910 of providing a lifting apparatus 50 comprising a hydraulic cylinder assembly 100 according to the present disclosure, and a lifting body 60 engaged with the inner piston rod 510 and the outer piston rod 410 and supporting the heavy machinery. The method 900 further comprises a step 920 of injecting inner and outer fluids simultaneously into the innerfluid-receiving chamber 230 and the outer fluid-receiving chamber 220 of the hydraulic cylinder assembly 100. The method 900 then comprises a step 920 of translating substantially simultaneously the sealing end portions 520, 420 of the inner and outer pistons 500, 400 respectively within the inner and outer fluid-receiving chambers 230, 220 along the longitudinal direction X1. The method 900 then comprises a step 940 of raising the lifting body 60 so as to lift the heavy machinery.

[0089] As mentioned above, the step 920 of injecting inner and outer fluids simultaneously into the inner fluid-receiving chamber 230 and the outer fluid receiving chamber 220 could comprise providing the inner and outer fluids by a single fluid supply. The step 920 could also comprise injecting the inner fluid with an inner fluid pressure into the inner fluid-receiving chamber and injecting simultaneously the outer fluid with an outer fluid pressure into the outer fluid receiving chamber, the outer fluid pressure being substantially identical to the inner fluid pressure.

Method for configuring the inner and outer pistons into the retracted configuration

[0090] The present disclosure also concerns a method for configuring the inner and outer pistons 500, 400 into the retracted configuration. The method for configuring the inner and outer pistons 500, 400 into the retracted configuration, when the inner and outer pistons 500, 400 are initially in the extended configuration, as represented in Fig. 3 (or any other intermediate configuration between the extended configuration and the retracted configuration) comprises injecting a feedback fluid into the upper fluid-receiving chamber 250 (or feedback fluid-receiving chamber 250). The feedback fluid conduit 684 is either fluidly connected to a feedback fluid supply 686 or feedback fluid source 686 (Figs. 2 and 3) different from the fluid supply 630 feeding at least one of the outer and inner fluid-receiving chambers 220, 230 (both chambers, in the embodiment shown) or to the same fluid supply. By injecting a feedback fluid into the upper fluid-receiving chamber 250, a fluid pressure is exerted on the upper fluid contacting surface 431 (or rod-facing surface 431 ) - as represented in Figs. 2 and 3 - opposed to the fluid-contacting surface 430 of the sealing end portion 420 of the outer piston 400 facing the outer fluid-receiving chamber 220. In the embodiment shown, the feedback fluid conduit 684 at least partially extends in the upper casing member-guiding sleeve 730, for instance in the cavity 712 formed between the lower casing member 710 and the outer barrel 200 (so that the lower casing member 710 forms a protection surrounding at least partially the feedback fluid conduit 684), and in the fluid supply cap 600 (for instance in the outer peripheral wall portion 604 thereof).

[0091] The method also comprises configuring the inner piston load-locking valve 810 and the outer piston load-locking valve 820 in an open configuration so that the inner and outer fluids contained respectively in the inner fluid-receiving chamber 230 and the outer fluid-receiving chamber 220 can be expelled thereof via the inner fluid supply conduit 610 and the outer fluid supply conduit 620.

[0092] Due to the injection of the feedback fluid in the upper fluid-receiving chamber 250, the sealing end portion 420 of the outer piston 400 is translated downwardly along the longitudinal direction X1 in the outer fluid-receiving chamber 220. Since the outer piston 400 and the inner piston 500 are mechanically connected to each other via their head-supporting end portions 440, 540, the sealing end portion 520 of the inner piston 500 is also translated downwardly in the inner fluid-receiving chamber 230 along the longitudinal direction X1 .

[0093] The sealing end portions 520, 420 of the inner and outer pistons 500, 400 are thus substantially simultaneously translated downwardly in the corresponding one of the inner fluid-receiving chamber 230 and the outer fluid-receiving chamber 220 along the longitudinal axis X1 to configure the inner and outer pistons 500, 400 in the retracted configuration. It is thus understood that only one of the inner and outer pistons 500, 400 (the outer piston 400, in the embodiment shown) is of the double-action type (i.e. is configurable from the extended configuration into the retracted configuration via the injection of a feedback fluid and from the retracted configuration into the extended configuration by injection of an outerfluid), whereas the second one of the inner and outer pistons 500, 400 (the inner piston 500, in the embodiment shown) is of the single-action type. The retroaction of the second one of the inner and outer pistons 500, 400 (i.e. its displacement for it to be configured in the retracted configuration) is mechanically driven by the first one of the inner and outer pistons 500, 400.

[0094] A hydraulic cylinder assembly 100 in which the inner cylinder 500 would be of the double-action type or both the inner and outer cylinders 500, 400 would be of the double-action type could also be conceived.

Method for lowering a heavy machinery

[0095] The present disclosure also concerns a method for lowering a heaving machinery. [0096] In the embodiment shown, the method comprises injecting a feedback fluid into the feedback fluid-receiving chamber 250 so as to lower the lifting body 60. In some embodiments, the feedback fluid is provided by at least one of an inner fluid source and an outer fluid source providing respectively the inner and outer fluids to the inner and outer fluid-receiving chambers 230, 220.

[0097] The present disclosure also concerns a kit for forming a hydraulic cylinder assembly 100 according to the present disclosure.

[0098] Several alternative embodiments and examples have been described and illustrated herein. The embodiments of the invention described above are intended to be exemplary only. A person of ordinary skill in the art would appreciate the features of the individual embodiments, and the possible combinations and variations of the components. A person of ordinary skill in the art would further appreciate that any of the embodiments could be provided in any combination with the other embodiments disclosed herein. It is understood that the invention may be embodied in other specific forms without departing from the central characteristics thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein. Accordingly, while the specific embodiments have been illustrated and described, numerous modifications come to mind. The scope of the invention is therefore intended to be limited by the scope of the appended claims.