LOCKABLE SUPPORT BY AUTOMATICALLY ACTIVATED SYSTEM

Description

[0001] The invention relates to a prop, more particularly a mason's prop.

[0002] The term prop in the following description refers to a mason's prop, that is, a prop which has all the robustness performance to support a structure, hold a concrete element, a framework, etc., unlike a prop or a rule, described as light or extensible which aims to support low loads of the type at most 30 kg.

[0003] Typically, a prop consists of an outer tube or shaft forming the lower part of the prop, an inner tube or slide forming the upper part of the prop, which slides within the tube and has several regularly spaced through holes, a captive pin or pin that passes through a hole to lock the slide in place, and a nut on the upper part of the tube to allow for fine adjustment of the prop's overall height and ensure effective clamping pressure. Generally, the nut has a pair of handles or lugs for tightening or loosening it.

[0004] However, such a prop systematically requires the use of both hands. Firstly, to lock the slide after its rapid approach against the surface to be supported—one hand holding the slide in place while the other inserts the pin into a through hole—and secondly, to fine-tune the tightening by turning the two lugs of the nut with both hands. Furthermore, to achieve a rapid approach without the risk of the prop's slide descending uncontrollably, it is known to integrate an automatic lowering locking system into the prop, such as the systems shown in patent applications FR2628466, EP1602791, FR1210466, and NL1025522. The locking pin can be pivoting. However, there is also a desire to save even more time and provide a simple and, above all, very quick locking mechanism for the operator.

[0005] The invention therefore aims to provide a simpler operating prop, in particular allowing it to be implemented with one hand, and even saving installation time, while maintaining its robustness.

[0006] According to the invention, the prop conforms to claim 1. In particular, the prop comprises a shaft, a slide adapted to slide in the shaft and comprising through holes distributed (regularly) along the length of the slide, a locking pin, preferably captive, intended to be inserted into a through hole to lock the slide in the deployed position, and a nut with a fine adjustment function for the height of the prop, the prop comprises an automatic system for locking the slide when lowering, which is adapted to be implemented automatically after deployment of the slide and before installation of the locking pin.

[0007] This design of the prop allows for one-handed operation. The user simply extends the sliding section with one hand, and upon releasing it, the section is automatically locked. With the same hand, while the other remains free, the user can then insert the locking pin, which secures the sliding section in position. This pin is essential for the load-bearing capacity of the masonry prop. Unlike previous designs, the user no longer needs both hands to set up the prop, which greatly facilitates operation on a construction site and allows them to use their other hand simultaneously for another task.

[0008] According to the invention, the automatic lowering locking system comprises a locking finger that is movable and pivotable (about an axis perpendicular to the slide axis) and that automatically engages in a through hole in the slide when the slide is released, without penetrating the slide's cross-section (diameter). The slide itself includes an anti-rotation means. Consequently, the locking finger temporarily locks the slide in position, and since it does not penetrate the slide's cross-section, it is very easy for the user to continue extending the slide if necessary, thanks to the finger's mobility, and to ensure automatic locking in another hole, as the slide cannot rotate.

[0009] In a preferred embodiment, the automatic down-locking system comprises a support piece that carries the spindle and a pivoting locking pin. The support piece is sleeve-shaped, surrounding the slide and resting on the barrel or nut, and has a first radial opening into which the locking pin is engaged and a second, opposite radial opening into which the spindle can be inserted. Preferably, the second radial opening communicates with a radial tubular housing that carries the spindle; the tubular housing provides, in particular, a guiding function for the spindle's translation in a plane perfectly orthogonal to the direction of the slide.

[0010] Another characteristic is that the locking finger is in a free position by gravity. This makes the system simple to manufacture, particularly as it eliminates the need for a spring-type elastic element. In its free position, the locking finger is able to abut against the slide during its extension; it is when the locking finger encounters a hole in the slide that it automatically engages.

[0011] Advantageously, the locking pin also constitutes an automatic indexing system for inserting the spindle. According to the invention, the spindle is fixedly positioned in the unlocked position (by means of a suitable support) so as to be radially opposite the locking pin. In this way, the spindle is always already in the engagement position in front of a through hole because the locking position is already indexed due to the indexing performed by the locking pin in position within a hole in the slide. The user does not have to think; with the slide locked in position at a through hole, the spindle can be inserted directly opposite the through hole, which houses the locking pin on the opposite side. The user simply has to translate the spindle into the through hole (in particular by a simple push), and locking is achieved extremely quickly.Since the locking finger is mobile, the spindle, when translated, will effortlessly push the locking finger, driving it out of the hole to completely pass through the section of the slide.

[0012] Furthermore, the fact that the spindle is fixedly arranged in the unlocked position so as to be radially opposite the locking finger allows the forces exerted on the support in the support position to be distributed, and thus avoids the risk of deforming the locking finger.

[0013] Another feature of the locking pin is a gripping extension located opposite the slide (facing the outside), allowing the locking pin to be manually lifted by pivoting. This makes it very easy to release the locking pin if the user needs to lower the slide when the locking pin has not been inserted. Furthermore, by unlocking the slide—that is, by removing the pin from the through hole with the locking pin outside the slide—the slide's weight immediately lowers it into its stowed position within the forestay's shaft.

[0014] The slide incorporates an anti-rotation mechanism relative to the automatic downward locking system. According to another feature, this slide has a longitudinal groove formed in the slide wall, offset from the longitudinal axes of the through holes. The automatic downward locking system, specifically the locking pin support (the inside of the support sleeve), has a complementary form of interaction with the groove. Advantageously, the barrel also incorporates an internal complementary form of interaction with the slide groove to prevent rotation of the slide when stored in the barrel, and in particular to ensure that the locking pin remains aligned with a through hole in the slide.

[0015] Another key feature of the prop is its ratchet mechanism for tightening and loosening the nut. This ratchet system is attached to the lower end of the nut, opposite the sliding joint, and comprises a ratcheting mechanism and an operating element such as an arm or handle. This ratchet system provides increased torque, allowing for very efficient tightening and effortless loosening. This design also enables the nut to be tightened or loosened within a tight angle, without requiring full rotations of the operating element, but rather a back-and-forth motion. This is advantageous in confined spaces, such as near a wall.

[0016] Advantageously, the nut operating system is a double ratchet system which includes a ratchet wheel whose inner circumference is engaged with the lower end of the nut, a double ratchet piece carrying two teeth and capable of being movable to position either tooth in cooperation with the ratchet wheel, and an operating arm to actuate the rotation of the ratchet wheel.

[0017] Advantageously, the operating arm is positioned opposite the double ratchet mechanism to the ratchet wheel (diametrically opposite), and preferably, the operating arm is capable of pivoting (upward or downward) around an axis perpendicular to the longitudinal axis of the prop, allowing it to be folded down and positioned at the desired angle. In this way, the operating arm is as close as possible to the shaft, thus reducing the compactness of the ratchet operating system. Furthermore, the pivoting function of the arm allows it to be positioned at an angle that adapts to the working space.

[0018] Preferably, the ratchet wheel is engaged with the lower end of the nut by being fixed to it by welding.

[0019] Preferably, the ratchet wheel and the double ratchet piece are arranged inside a closed body which has two windows from which two actuation surfaces are accessible for rotating the double ratchet piece.

[0020] According to yet another characteristic, the strut includes at least one end stop for the slide inside the barrel, in particular a stop which is integral with the barrel (integral with the inside of the upper end of the barrel) and against which an element integral with the slide is able to cooperate to ensure an end of the slide deployment.

[0021] According to yet another characteristic, the stay has two lower and upper plates, respectively attached to the shaft and the slide, which have soles made of plastic material, in particular rubber, preferably the soles being removable.

[0022] The invention also relates to a method of implementing a prop of the aforementioned invention, according to claim 12, this method comprising a step of deploying the slide to a desired height, a step of locking the slide via the insertion of the pin into a through hole, and optionally tightening the nut, characterized in that it comprises after the step of deploying the slide and before the locking step, a step of releasing the slide causing the automatic locking of the slide via the automatic system of locking on descent of the slide, in particular the step of deploying the slide being done with one hand, and the locking step being able to be done with the same hand.

[0023] According to the invention, the automatic locking is achieved by the locking finger automatically entering a through hole in the slide (the nearest hole being located immediately above the locking finger at the time of the slide's release), and the locking is achieved by translating the spindle into the through hole opposite the locking finger until it is driven out of the slide (and in such a way as to absorb the vertical load).

[0024] The slide folds back automatically by pulling the spindle out of the slide.

[0025] In the following description the term "height", the qualifiers "upper", "lower", "top" and "bottom" of an element of the prop are used in the context of a normal installation of the prop, that is to say relating to a vertical notion in relation to a ground on which the prop would be placed.

[0026] Features and other advantages of the invention will become apparent from the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings, in which: [ Fig. 1] ou figure 1 represents a perspective view of a preferred embodiment of a prop according to the invention in the fully stowed position of the slide. Fig. 2] ou figure 2 represents a side view of the forestay of the figure 1 , in the deployed and locked position of the slide, and before locking. Fig. 3] ou figure 3 is a partial vertical cross-sectional view of the strut of the figure 1 showing the blocked position of the slide thanks to the automatic sliding block system; the cooperation of the automatic block system with the slide when the latter is in the deployed position is the same. Fig. 4] ou figure 4 represents a side view of the forestay of the figure 1 in the deployed and locked position of the slide. Fig. 5] ou figure 5 corresponds to a partial vertical cross-sectional view of the strut of the figure 4 along a vertical median plane passing through the through holes. Fig. 6] ou figure 6 This corresponds to the partial vertical cross-sectional view of the strut during the deployment of the slide and before the slide is locked. Fig. 7] ou figure 7 is a cross-sectional view along the horizontal median plane of the ratchet operating system of the nut. Fig. 8] ou figure 8 is a perspective view of the slide in its deployed position, with the automatic lowering locking system of the slide intentionally translated to show the nut from a top-down view. Fig. 9] ou figure 9 corresponds to a tilted view of the figure 8 to view, from a bird's-eye perspective, the underside of the automatic lowering locking system of the slide. Fig. 10] ou figure 10 is a cross-sectional view of the foot of the strut in the folded position of the slide, showing the lower end stop for the slide. Fig. 11] ou figure 11 is a cross-sectional view of the upper end of the stay shaft in the fully extended position of the slide, and showing the upper end stop for the slide.

[0027] The prop 1 of the invention illustrated on the figures 1 And 2comprising a shaft 2 forming the lower part of the prop, a slide 3 adapted to slide within the shaft 2, forming the upper, telescopic part of the prop and including through holes 3' regularly spaced along the length of the slide, an automatic system 4 for temporarily locking the slide 3 in its downward position once the latter is in the deployed position, a locking pin 5 for the slide 3 to prevent its descent into the prop's operating position, the pin 5 being adapted to cooperate with a through hole 3', a nut 6 for fine-tuning the height of the prop, and an operating system 7 for the nut 6, adapted to tighten and loosen the nut. Preferably, the automatic downward locking system 4 also forms an automatic indexing system for the pin 5, systematically aligning it with a hole 3' in the slide 3.

[0028] Prop 1 is a mason's prop with all the robustness expected for this type of prop.

[0029] The automatic system 4 for temporarily locking the slide 3 in its downward position will be described later; it allows the slide 3 to be operated with one hand, without needing the other hand to lock it in position. Indeed, when the user stops extending the slide 3 upwards, the slide 3 is automatically locked in position and cannot be lowered again; this temporary lock allows the user to use the same hand to grasp the pin 5 in order to lock the slide 3 in position. Furthermore, when the automatic temporary locking system 4 incorporates the indexing function, the pin 5 is automatically aligned with a hole 3', and the user only needs to translate the pin 5 horizontally (horizontal push) to lock the slide 3. The term "temporary" means that the sliding lock of the slide is not engaged via the pin 5.

[0030] Furthermore, the operating system 7 of the nut 6 illustrated in the embodiment example and detailed further on opposite the figure 7 , is a ratchet operating system that provides ease of screwing and unscrewing by providing more torque.

[0031] The shaft 2 comprises a hollow tube 20, a lower plate 21 at the foot of the stay and serving as a base for the stay, and preferably, a foot reinforcement 22 of a type known per se by forming a double tube surrounding the lower end of the tube 20.

[0032] The lower plate 21 advantageously includes a sole 23 made of plastic material such as rubber.

[0033] As shown on the figure 3 The upper distal end of the tube 20 of the shaft 2, opposite the base of the shaft, is threaded to receive the nut 6. The nut 6 is a simple tube 60 whose interior is tapped to engage with the threaded distal end of the shaft 2. As usual, tightening the nut 6 slightly raises the slide 3, which is locked in place by the pin 5, to fine-tune the height of the strut and bring it fully into compression against the surface to be supported. The operating mechanism 7 for the nut 6 and its coupling with the slide 3 are described later.

[0034] The slide 3 has a hollow tube 30 which is able to slide within the hollow tube 20 of the barrel 2. The tube 20 of the barrel 2 has inside it, at its base, a limit stop 24 (visible on the figure 10 ) for the lower end of the slide 3. The end stop 24 is, for example, a transverse axis to the shaft 2 and fixed by bolting to the foot reinforcement 22. In addition, the strut includes ( figures 10 et 11 ) a limit switch element 25 for the deployment of the slide and a stop 26, to prevent the slide 3 from coming out of the barrel 2. The limit switch element 25 is a radial part projecting from the tube 20; its protrusion from the body of the slide is limited to allow the slide 3 to slide inside the tube 20. The stop 26 is located at the upper inner end of the tube 20 and is designed to block the slide from translation when the projecting part of the element 25 comes into contact with said stop 26.

[0035] The slide 3 has at the upper distal end of the tube 30 a plate 31, called the upper plate, which is intended for support. Preferably, the upper plate 31 includes a base 32 made of a plastic material such as rubber.

[0036] Furthermore, slide 3 includes (notably visible on the figures 3 à 6 ) a plurality of regularly spaced through holes 3'. The through holes 3' form diametrically opposed bores aligned along two diametrically opposed longitudinal axes, extending along the height of the tube 30. The pin 5 is designed to cooperate with a through hole 3' in a radial direction to the tube 30 to lock the slide 3 in position. The pin 5, by passing through the entire diameter or cross-section of the slide 3, completely locks the slide 3, preventing it from descending unexpectedly.

[0037] The pin 5 is captive. The pin 5 is fixed to a ring 50 which surrounds the slide 3. In addition, the pin 5 is supported by a support piece 40 which is part of the automatic temporary locking system 4.

[0038] The automatic temporary locking system 4 for the downward movement of the slide 3 allows the slide 3 to be temporarily locked until the spindle 5 has been installed in the locked position. The automatic temporary locking system 4 comprises the support piece 40, which surrounds the tube 30 of the slide 3 (and is free to move in translation), and a locking member 41, which prevents the slide tube 30 from sliding relative to the support piece 40 (until the spindle 5 is in the locked position). The support piece 40 is therefore circularly perforated when viewed from above, allowing the tube 30 of the slide 3 to slide through it. The support piece 40 also has a shoulder 42 at its lower end so that it can rest on the barrel 2 or the nut 6 when the nut protrudes from the barrel 2 in the screwed position.

[0039] In the preferred example shown, the support piece 40 forms a socket and includes in its wall a first orifice 40' arranged radially in the wall, while the locking member 41 forms a locking finger which is able to be movable to cooperate with the orifice 40' of the support piece 40 and a hole 3' of the tube 30 of the slide 3 ( figure 3 ). The locking finger 41 is movable by pivoting around an axis orthogonal to the axis of the slide 3. The locking finger 41 is capable of adopting two positions, a so-called locking position which corresponds to its engagement up to a hole 3' of the slide 3 ( figure 3 ), and a position called the exit position which corresponds to its disengagement from a 3' hole in the slide ( figure 5 ). When the pin 5 is not in its locking position, i.e., fully through the slide 3 via a through hole 3', and the locking finger 41 assumes a free position by its own gravity, said locking finger 41 is systematically arranged through the orifice 40' of the support piece 40 ( figures 3 And 6 ). During the deployment of the slide 3, the locking finger 41 passes alternately in front of a hole 3' in the slide and in front of the wall of the tube 30, butting against it ( figure 6 ). Thus, when the slide 3 is released, the locking finger 41 automatically enters the immediately nearest through hole 3' temporarily blocking the slide in translation.

[0040] The locking finger 41 has a free end 41A for cooperation with the slide 3 and an opposing free end 41B, referred to as the gripping end, facing the external environment and suitable for manual grasping. The locking finger 41 is able to pivot by pushing on its cooperation end 41A during the upward translation of the slide 3, or by pulling on its gripping end 41B, and is able to return to its free position by gravity. The locking finger 41 is not coupled to any spring or elastic element.

[0041] To ensure the pivoting of the locking finger 41, the automatic locking system 4 preferably includes a stirrup 43 ( figure 1 comprising a core 43A and two opposing wings 43B and 43C, the locking finger 41 being integral with the core of the stapes, while the distal ends of the wings 43B and 43C of the stapes are pivotally fixed to the support piece 40. The stapes 43 is thus able to pivot about an axis parallel to the core 43A of the stapes. The locking finger 41 is integral with the core 43A of the stapes 43, and has its cooperating end 41A projecting orthogonally to the core 43A and inwards towards the stapes between the two wings 43B and 43C, and its grasping end 41B projecting in the opposite direction outwards from the stapes. Thus, the pivoting of the locking finger 41 is ensured by the pivoting of the stirrup 43.

[0042] In the folded position of the stay 1, when the slide 3 is completely stowed in the barrel 2 ( figure 1 ), the end stop 24 for the slide 3 has been positioned so that the support piece 40 of the automatic locking system 4 has its radial orifice 40' directly opposite a hole 3' in the slide. Thus, in the folded position of the strut 1, the support piece 40 rests by its shoulder 42 on the barrel 2, or possibly on the nut 6 if the latter is screwed in slightly protruding from the barrel, and the locking finger 41 is in the engaged position by passing through the orifice 40' of the support piece 40 and through a hole 3' in the slide ( figure 3 ).

[0043] As soon as the user wants to extend the slide 3 and position it at a certain height, they simply lift the upper plate 31, then, stopping their movement while releasing the slide 3, the locking finger 41, which is already positioned through the opening 40' in the support piece 40, automatically enters the nearest hole 3' in the slide and is thus positioned as in the configuration of the figure 3 The cooperation end 41A of the locking finger 41 is advantageously beveled with a downward slope, which facilitates the immediate release of the locking finger during its pivoting, thus preventing the bottom of the locking finger from hitting the lower part of the orifice 40' of the support piece during pivoting ( figure 6 ). The other advantage of the beveled shape is to facilitate the automatic disengagement of the finger from the 3' holes when sliding upwards in the slide, and its direct insertion into a hole when the sliding is stopped.

[0044] Finally, the locking finger 41, through its systematic interaction with a through hole 3' in the slide 3, provides an indexing mechanism for the pin 5 to be inserted into this same through hole 3'. The user does not need to think; as soon as the slide 3 is in a temporarily locked position, they know that this position is the one required to directly insert the pin 5 and thus lock the slide 3.

[0045] Advantageously, the support piece 40 carries the spindle 5 by its free end 5', which is engaged in a radial tubular housing 44 projecting from the outside of the support piece. The tubular housing 44 communicates directly with a second radial opening 44' in the support piece 40, which is opposite the first radial opening 40' that houses the locking pin 41. In this way, the spindle 5 is always aligned with a through hole 3' in the slide 3. Thus, the automatic locking system 4, by means of its locking pin 41 and its support piece 40, which supports and prepositions the spindle 5, constitutes a means of indexing the spindle 5 with respect to the through holes 3' in the slide 3.Furthermore, the radial tubular housing 44 forces the spindle 5 into an orthogonal position relative to the tube 30 of the slide, and thus imposes a perfect position opposite a through hole 3' in the slide, while also participating in the translational guidance of the spindle 5. The user only has to push on the ring 50 in a horizontal direction to translate the spindle 5 towards the locking finger 41 until the said locking finger 41 is pushed, which then pivots out of the first radial orifice 40' of the support piece 40, allowing the spindle 5 to completely traverse the slide 3 (. figure 5 ) thus locking the slide 3.

[0046] The automatic system 4 for temporarily blocking the downward movement of the slide 3, described above, comprising the socket-shaped support piece 40 with two opposing radial holes, and the locking finger 41, has been given as an example. Other variations are possible. For example, the support piece 40 for the spindle 5 could include an upper plate with a downward-curved surface, while the spindle ring would be arranged under the upper plate with its free end abutting the curved surface, thus preventing the slide from descending. This temporary blockage would then allow the spindle to translate to secure the locking. However, this variation, although providing temporary blocking of the slide, does not provide indexing for the locking process.Indeed, in the absence of the locking finger which cooperates with a 3' through hole in the slide, this variant does not allow the slide to be locked automatically so that the locking pin 5 can be directly opposite a 3' through hole in the slide.

[0047] The slide 3 includes an anti-rotation system relative to the support piece 40, so that the locking finger 41 is always opposite the longitudinal axis of the through holes 3'. A preferred embodiment of the anti-rotation system is illustrated in the figures 8 et 9 : by translating the support piece 40 towards the upper plate 31 to view the inside and the underside of the support piece 40, we see that the tube 30 of the slide 3 has a longitudinal groove 33 cooperating with a complementary form 45 integral with the inside of the support piece 40. Similarly, the inside of the tube 20 of the barrel 2 advantageously has a complementary form 26 cooperating with the groove 33 of the slide 3 so as to prevent the rotation of the slide 3 in the stowed position.

[0048] Finally, the operating mechanism 7 for nut 6 could be a pair of handles forming a pair of ears, as in the prior art. However, in the preferred embodiment shown, the operating mechanism 7 for nut 6 consists of a ratchet tightening and loosening system. As shown in the figure 7The ratchet operating system 7 is integral with the lower end 61 of the nut 6. It comprises, within a preferably metallic body 70, a ratchet wheel 71 fixed (preferably by welding) around the lower end 61 of the nut, a double-ratcheting piece 72 having two spaced teeth 72A and 72B adapted to selectively engage with the ratchet wheel 71, and, outside the housing, an operating arm 73 for rotating the body 70. The ratchet wheel 71 lies in a plane transverse to the nut 6. The double-ratcheting piece 72 forms a pivoting part adapted to be moved between two positions to engage either of the teeth 72A and 72B with the ratchet wheel 71 in order to control the direction of rotation of the ratchet wheel 71, and consequently tighten or loosen the nut. 6. The double ratchet piece 72 is pivotal about an axis 72' parallel to the longitudinal body of the nut 6.The double ratchet piece 72 has two surfaces 72-1 and 72-2 accessible externally to the body 70 (via two windows 74-1 and 74-2 of the body 70); pivoting is achieved by alternately pressing on one or the other of the surfaces 72-1 and 72-2. Preferably, the operating arm 73 is foldable by pivoting downwards and upwards, which reduces its size when not in use by allowing it to be folded vertically parallel to the forestay, and which facilitates its operation, particularly when the lateral clearance at the forestay does not allow the arm 73 to be arranged completely horizontally.

Claims

1. A prop (1) comprising an outer tube (2), an inner tube (3) capable of sliding in the outer tube (2) and comprising through holes (3') distributed along the length of the inner tube, a locking pin (5), preferably captive, intended to be inserted into a through hole (3') in order to lock the inner tube (3) in the extended position, and a nut (6) for finally adjusting the height of the prop, as well as an automatic system (4) for blocking the descent of the inner tube (3), which is capable of being implemented automatically after the inner tube has been extended and before the locking pin (5) has been placed, wherein the automatic blocking system (4) comprises a blocking catch (41) that is capable of being pivoted, characterised in that the blocking catch (41) is capable of being inserted automatically into a through hole (3') in the inner tube when the inner tube is released without passing through the entire section of said inner tube, and the pin (5) is fixed in the non-locking position so as to face the blocking catch (41) radially, while the inner tube (3) comprises an anti-rotation means.

2. A prop according to any one of the foregoing claims, characterised in that the automatic system (4) blocking descent comprises a support part (40) holding the pin (5) and a blocking catch (41) capable of pivoting, wherein the part has the shape of sleeve surrounding the inner tube (3) and rests on the outer tube (2) or the nut (6), and is provided with a first radial orifice in which the blocking catch (41) is engaged and a second opposite radial orifice (44') into which the pin (5) can be inserted, where the second radial orifice is preferably in communication with a radial tubular housing (44) which holds the pin (5).

3. A prop according to any one of the foregoing claims, characterised in that the blocking catch (41) also constitutes an automatic indexing system for inserting the pin (5).

4. A prop according to any one of the foregoing claims, characterised in that the blocking catch (41) is in a free gravity position.

5. A prop according to any one of the foregoing claims, characterised in that the blocking catch (41) can be moved by pivoting and comprises a grasping extension (41B) which is placed opposite the inner tube.

6. A prop according to any one of the foregoing claims, characterised in that the inner tube (3) comprises a means for preventing rotation relative to the automatic system (4) for blocking the descent of the inner tube, in particular the inner tube (3) comprises a longitudinal groove (33) which is formed on the wall of the inner tube and is offset relative to the longitudinal axes of the through holes, while the automatic system (4) for blocking the descent of the inner tube has a complementary shape for cooperating with the groove, preferably the interior of the outer tube (2) also has a complementary shape (25) for cooperating with the groove (33) of the inner tube.

7. A prop according to any one of the foregoing claims, characterised in that it comprises a ratchet operating system (7) for screwing and unscrewing the nut (6).

8. A prop according to the foregoing claim, characterised in that the ratchet operating system (7) is a double pawl system which comprises a ratchet wheel (71) whose inner circumference is engaged with the lower end of the nut, a double pawl part (72) bearing two teeth (72A, 72B) and capable of moving to position either tooth in cooperation with the ratchet wheel (71), and an operating arm (73) for rotating the ratchet wheel (71), wherein preferably the ratchet wheel (71) and the double pawl part (72) are arranged inside a closed body (70) which has two windows (74-1, 74-2) from which two operating surfaces (72-1, 72-2) are accessible for pivoting said double pawl part.

9. A prop according to the foregoing claim, characterised in that the operating arm (73) is placed opposite the double pawl part (72) with respect to the ratchet wheel (71), wherein preferably the operating arm (73) is also capable of pivoting around an axis perpendicular to the longitudinal axis of the prop.

10. A prop according to any one of the foregoing claims, characterised in that it comprises at least one limit stop (24, 26) for the inner tube (3) inside the outer tube (2), in particular a stop (26) which is integral with the outer tube (2) and against which an element (25) integral with the inner tube (3) is capable of cooperating in order to provide a limit stop for the extension of the inner tube.

11. A prop according to any one of the foregoing claims, characterised in that it comprises two plates, base and top plate (21, 31), integral with the outer tube and the inner tube respectively, which comprise pads (22, 32) made of plastic material, particularly rubber, wherein the pads are preferably removable.

12. A method of implementing a prop according to any one of the foregoing claims, comprising a step of extending the inner tube (3) to a desired height, a step of locking the inner tube by inserting the pin (5) into a through hole (3') and possibly tightening the nut (6), characterised in that it comprises, after the step of extending the inner tube (3) and before the locking step, a step of releasing the inner tube, resulting in the automatic blocking of the inner tube by the automatic system (4) for blocking the descent of the inner tube; in particular, the inner tube extension step is performed with only one hand, and the locking step can be performed with the same hand, wherein automatic blocking is performed by the blocking catch (41), which is automatically inserted into a through hole (3') in the inner tube, and locking is achieved by displacing the pin (5) opposite the blocking catch (41) so as to push the blocking catch until it is driven out of the inner tube (3) and the pin passes through the entire section of the inner tube.