FR2747380A1 - METHOD AND DEVICE FOR SECURE ACCESS TO A HIGH DRIVING STATION, IN PARTICULAR ON A TOWER CRANE - Google Patents

Abstract

The invention relates to access to an elevated driving position, such as a tower crane cab (16), accessible by a mast (5) in one or more parts (10, 11, 12) fitted laterally with scales (13, 14, 15). A personal protection basket (17), inside which the crane operator can stand, is mounted mobile along the mast (5), being held and guided on the ladders (13, 14, 15). The nacelle (17) is driven by the crane operator on its path, during the ascent or descent of the ladders, by means of a harness or a harness. Means (18, 19) compensate for the weight of the nacelle (17) and allow it to be immobilized. Application: telescopic mast tower crane (5).

Description

The present invention relates to a method for secure access to a station

  of high driving, more particularly to the cabin of a tower crane. It also relates to a device for implementing the method. This invention finds particular application for access to the cabin of tower cranes self-assembly, telescopic or folding,

  used on construction sites of buildings.

  In use, the cabin of such a crane is generally arranged at the top of the mast, so that the crane operator, taking place in this cabin for driving the crane, can have good visibility on all work operations. To access the cabin, the mast of the crane is traditionally equipped with ladders and protective cages called "crinoline" fixed, arranged either inside the mast when the cross section of this mast is sufficient for the passage of the crane operator outside the mast when the section of the mast is insufficient, which is often the case for

automated editing.

  In all cases, the ladders must have rest stops placed at levels such that each ladder run does not exceed a permitted value. Preferably, the flocks of successive ladders are offset laterally relative to each other, to ensure better ergonomics. However, during climbing or descending ladders, the crane operator is not immune to a fall inside the crinoline, a height of up to several meters. Fixed crinolines are therefore not protections

  perfect against the risk of falling.

  In addition, in the case where ladders and crinolines are arranged outside the mast, crinolines in particular have a significant wind resistance, which limits the mechanical strength and the height of autonomy of the crane in service. The presence of external crinolines also implies additional space which hinders the folding of the crane in position

  transport and increased vulnerability.

  To overcome some of the foregoing drawbacks, European Patent Application No. 0.175.052 discloses an embodiment in which the cab is slidably mounted along the mast of the crane, and in which the crinoline device of the ladders of access to the cabin, which is also sliding along the mast and interconnected by cables or straps, is suspended under the cab. In the transport position of the crane, the cabin is lowered to the foot of the mast, and the hoops of the device of crinolines stack on top of each other, while presenting a footprint as small as possible. Such an embodiment is interesting for the road transport of the crane, but it presents technical difficulties and a significant additional cost, in particular to ensure the correct guidance of the arches of crinolines during the

  sliding, and maintaining in position these arches.

  Also known are access devices at the top of the mast of a crane, including high, consisting of a real elevator car flowing inside the mast - see International Patent Application No. WO 92/18412. Such a solution is conceivable only for masts of large cross section. It is particularly expensive because it requires motor means, braking means and

  specific safety features.

  Moreover, in the field of ladders in general, it has already been proposed many safety devices more or less effective, for the rise and fall of the ladder, as well as devices forming a work platform or intervention, may be

  placed at the desired height on a ladder.

  In particular, the French patent application No. 2,495,684 discloses a sliding protector, constituted by a sort of rolling trolley along the amounts of a ladder, and laterally provided with handles seized by the operator during the climb of the ladder. This device has in itself many disadvantages, and it is neither intended nor adapted for access to a high driving position, such as a crane cabin: - The device does not provide complete protection, c that is, at the same time lateral, inferior and

  possibly higher than the operator.

  - The use of such a device is particularly tiring, since the user must climb to scale by the strength of his legs, without

to be able to help himself with his arms.

  This disadvantage is aggravated by the fact that the device has no means of compensation for its

  weight, which is added to that of the user.

  - The device does not offer real security, in the sense of a firm immobilization of this device on the scale, at any height; the use of the only spring pressure is noticeably insufficient to immobilize the protector on the

amounts of the ladder.

  - The training of the device along the ladder, during the climb, is only by holding the handles, which requires a voluntary and unusual gesture; a crotch strap retains the user but does not allow the drive of the device to the

  high, when climbing the ladder.

  - The device does not include any means facilitating its access from the outside, and the output of the user; in particular, there is no provision for the user, arrived in the high position, safely out of the protector, to win a high driving position, including a tower crane cabin which would be on the side of the ladder. - Finally, this known device is not really suitable for switching from one ladder to another, with continuous guidance, while cranes with telescopic or folding mast usually have a succession of ladders. Thus, the solution disclosed by the French patent application N 2,495,684, moreover formulated in a very succinct manner, proves to be non-ergonomic and even totally unrealistic, in particular with respect to the specific field of application of the

present invention.

  It is also possible to note U.S. Patent No. 2,245,661, in which is described a harness device, movable along a ladder and used for performing work at height. Thus, this device is a small work platform, which can be hung at the desired level on the rungs of a ladder, but like the previous one it is not designed for secure access to a driving position located at a height, in particular at the cabin

of a tower crane.

  The present invention aims to overcome the disadvantages set out above, by providing a method and a device for secure access to a high driving position, including the cabin of a tower crane, which limit the effects of the wind to increase the mechanical resistance and the height of autonomy of the crane, and which facilitate the folding of the crane for its transport on road, while ensuring an ergonomics and a security optimal, during the ascent and the lowering of the mast than during the passage of the crane operator

  the ladder to the cabin, and vice versa.

  For this purpose, it is essentially proposed a method for secure access to a high driving position, in particular on a tower crane, accessible by a mast or the like in one or more parts equipped laterally with one or more ladders. access to a driving position or cabin, which method according to the invention consists in using an individual protection device, mobile along the mast, maintained and guided on the ladder or successively on the ladders and driven by the crane operator on his way , when climbing up the ladder or ladders to the cabin and

  conversely when descending from the cabin.

  As is easily conceivable, the fact of using a mobile personal protective device accompanying the crane operator during its ascent or descent, between the ground and the cabin, allows to remove the traditional fixed crinolines, so to limit the effects of the wind, grace

  the significant reduction of the surfaces exposed to the wind.

  The removal of crinolines also facilitates the folding and transport of the crane, and makes it much less vulnerable; it will be noted that, for the transport of the crane, the personal protection device is reduced to

  the base of the crane mast, or even removed from the crane.

  This device performs mainly permanent protection, closer to the crane operator, and it can also ensure, at any time and in any position along the mast, a platform function of rest or intervention. According to one embodiment of the method of the invention, the personal protection device is driven along the mast, via a harness resting on the shoulders of the crane operator. According to another embodiment of this method, the individual protection device is driven along the mast by

  via a shoulder belt supporting the crane operator.

  In any case, the personal protection device can accompany the crane operator, when climbing or descending the ladder, which always take place in a normal gesture, the crane operator putting his hands and feet on the bars of the ladder. The device, according to the invention, for secure access to a high driving position, in particular on a tower crane, for the implementation of the method defined above, comprises an individual protection pod, accessible from the outside. , inside which the crane operator can stand, the nacelle being provided with means for holding and guiding the mast ladder or ladders, and a harness or harness for training by the crane operator, the device comprising still means of compensation of the weight of the nacelle and means

immobilizing said nacelle.

  Advantageously, the nacelle protection is presented as a closed rigid structure but perforated, consisting of horizontal arches joined by vertical rails, a floor at its base and having a platform function of rest and intervention, and possibly, a protective roof in its upper part. Thus, this structure provides a lateral protection, dorsal, inferior and, where appropriate, superior. According to a complementary feature, the nacelle protection is provided with a side access door, opening inwardly, and an emergency hatch made in the floor. The side door facilitates the access of the crane operator inside the nacelle, when it is in the low position, and it allows above all, in the high position of the nacelle, a passage of the crane operator safely from the nacelle to the cabin, and vice versa. The fact that the door only opens towards the inside of the nacelle avoids any risk of falling as a result of a push against this door, or an untimely opening whatever the cause,

  while the nacelle is at an intermediate height.

  According to another characteristic, the means for holding and guiding the protective nacelle consist of pairs of rollers mounted in lines respectively on crosspieces fixed symmetrically on either side of the nacelle, on the one hand, at the level of its lower part or floor and, on the other hand, at an intermediate level between the lower part or floor and the upper part of the nacelle, the pairs of rollers bearing continuously on the

  ladder amounts or mast ladders.

  According to a complementary feature, in the case of a mast with successive elements, of different sections from each other, carrying respective ladders, it is expected that free spaces, substantially equal to the thickness of the mast ladder amounts, are arranged between the different lines of rollers, in correspondence with the different positions of the ladders on the mast elements. The passage of the protective nacelle, from one scale to the next, is thus carried out without discontinuity, whatever the

number of scales.

  In a particular embodiment, the weight compensation means of the protective nacelle consist of a winch, equipped with a torque motor, fixed to the top of the mast, the cable of the winch down below the nacelle and being fixed at a point located at the upper part of said nacelle. These means make it possible to compensate for the weight of the platform driven by the crane operator, so that the effort to be provided by the crane operator during the climb is practically not increased. In addition, by the appropriate adjustment of the effort to compensate for the weight of the nacelle, it is ensured that the nacelle is actually driven by the crane operator, either through the harness, or through the shoulder belt. As for the means of immobilization of the nacelle protection, in a particular embodiment, they consist of a retractor provided with an anti-fall device operating by inertia, known per se, fixed to the top of the mast substantially to the plumb of the nacelle, the cable of the retractor being fixed at a point located at the upper part of said nacelle. Such means stop immediately the beginning of fall of the nacelle, so the

  crane operator who is inside.

  The device previously defined is more particularly applicable to the access to a cabin of a self-erecting tower crane, with telescopic or folding mast composed of successive mast elements bearing respective ladders, on which is maintained and guided the nacelle protection. It may be, inter alia, a tower crane whose cabin, to which this device gives access, is itself mobile along the mast of the crane, and in particular guided on the same scales as the nacelle of protection. Such a cabin can be immobilized at any intermediate height, and it will be noted that the device according to the invention in this case allows access to the cabin, regardless of its level of immobilization. Even more particularly, the invention is applicable to a tower crane with a telescopic mast in which the ladders, other than the ladder of the lower mast element, are rigidly fixed, only by their upper part, at the top of the mast. corresponding mast element, the ladders being shifted transversely relative to one another and being provided with a median rail for holding and guiding the lower end of the ladder of the immediately higher mast element, this end being equipped with a rolling and / or sliding means cooperating with the rail. These arrangements allow the telescoping of the mast with its ladders, and ensure the maintenance in position of the ladders, to allow the passage of the nacelle protection from one ladder to the next, during its rise,

  or to the previous one, during his descent.

  In any case, the invention will be better understood

  using the following description, with reference to the drawing

  schematic annexed which, by way of example, illustrates modes of implementation of this method for secure access to a high driving position, and represents embodiments of the associated device, in the case of application to a tower crane: FIG. 1 is an overall side view, in the assembled state, of a tower crane to which the method according to the invention applies, the protective nacelle of the access device to the cabin occupying its low position; Figure 2 is an overall rear view of the same crane, corresponding to Figure 1; Figure 3 is an overall side view of the same crane, the protective nacelle occupying its high position; Figure 4 is a rear view of the same crane, corresponding to Figure 3; Figure 5 is a detailed side view of the nacelle protection, guided on a scale and associated with means for compensation of its weight and immobilization, in a first embodiment; Figure 6 is a top plan view of the nacelle protection according to Figure 5, showing its arrangement relative to the cabin of the crane; Figure 7 is a detail side view of the protective nacelle, guided on a scale and associated with means for compensation of its weight and immobilization, in a second embodiment; Figure 8 is a detail rear view of the nacelle of Figure 7, showing its arrangement with respect to the crane cabin; Figure 9 is a plan view from above of this nacelle, corresponding to Figure 8; Figure 10 is a partial side view of the mat, and associated ladders, of a tower crane to which the invention is applied; Figure 11 is a plan view from above

  the set of ladders equipping the mast of this crane.

  The tower crane, represented as a whole in FIGS. 1 to 4, comprises, in a known manner, a fixed or rolling base frame 1 supporting, by means of an orientation device 2 of vertical axis 3, a rotating frame 4 which carries a mast 5. This tower crane is provided with a distributing arrow 6, carried by the top of the mast 5 and held horizontally by means of a tie rod 7, a punch 8 and a rear stay 9 , connected to the back

rotating chassis 4.

  In the particular case illustrated in the drawing, the mast is telescopic. It consists of three successive mast elements 10, 11, 12 whose respective cross sections are different and decreasing from bottom to top, to allow telescoping. Each mast element, 11, 12 carries a scale, respectively 13, 14, 15, attached laterally to this mast element. As shown schematically in FIGS. 2 and 4, the scales 13, 14, 15 are offset transversely, relative to each other.

  to others; this provision will be specified below.

  The crane is provided with a cabin 16, carried by the mast 5 and offset laterally with respect to the mast 5 and the arrow 6. The cabin 16 occupies, in particular, when the crane is in use, a high position, at the top of the mast 5. However, it should be noted that this cabin 16 can also be immobilized at an intermediate height on the mast 5, when the crane is in service, or down at the foot of the mast 5 for folding the crane,

  said cabin 16 being guided on the ladders 13, 14, 15.

  According to the invention, the crane is equipped with a device for access to the cabin 16, placed at the chosen height, this device enabling the crane operator

  to gain safe access to the cabin 16 from the ground.

  The device generally comprises a protective nacelle 17 inside which the crane operator can stand, compensation means 18 for the weight of the nacelle 17, and immobilization means 19 of said

nacelle 17.

  As shown in FIGS. 5 and 6, relating to a first embodiment of this device, the protective nacelle 17 comprises a rigid, closed but perforated structure, composed of horizontal arches 20 joined by vertical rails 21, a floor 22 situated at the base of the structure, and a harness 23 located in half

superior of this structure.

  The protective nacelle 17 is equipped, at the floor 22 and at an intermediate level between the floor 22 and the harness 23, two superposed pairs of horizontal crosspieces 24 and 25, symmetrically fixed on either side of the nacelle 17 The crosspieces 24 and bear respectively rollers 26 and 27, horizontal axes spaced horizontally from the thickness e of the uprights 28 of the ladders 13, 14, 15 of the mast 5. In the example illustrated, each crossbar 24 or 25 carries four rollers 26 or 27 mounted in rows, leaving between them three identical free spaces of value e, respectively corresponding to the passage of the uprights 28, offset

  horizontally, different scales 13, 14, 15.

  The protective nacelle 17 is further provided with a lateral access door 29, hinged about a vertical axis 30 and opening towards the inside of the nacelle (see FIG. 6), and an emergency hatch. 31 arranged

in the floor 22.

  The upper part of the nacelle 17, indicated at 32, possibly forms a protective roof, no

shown in detail.

  The compensation means 18 of the weight of the nacelle 17 consist, in the examples considered, in a winch 33, equipped with a torque motor, the cable 34 is fixed at an attachment point 35, to the upper part 32 of the nacelle 17. The winch 33 is fixed to the top of the mast; it can be supported in particular by platform 36 of

winch lifting the crane.

  The immobilizing means 19 of the protective pod 17 consist, for their part, of a winder 37 unwinding or automatically winding a cable 38 which is fixed, at a point of attachment 39, to the upper part 32 of the nacelle 17 The reel 37 is provided with a fall arrest device operating by inertia; it can still be provided with a control cable, provided for manual control. This winder 37 is fixed to the top of the mast 5, and it can be supported in particular by the

  platform 36 of hoist crane hoist.

  The immobilization means 19 previously described allow immobilization of the nacelle 17 protection at any intermediate height. These immobilization means are advantageously completed by means, mechanical or electro-mechanical, automatic locking of the nacelle 17 in the low position and in

  high position, with manual unlocking.

  The operation of the device previously described, for access to the cabin 16 of the crane, is as follows: Initially, as shown in Figures 1 and 2, the crane is in the assembled state with the cabin 16 disposed at the top of the mast 5 (the cabin 16 having been previously brought to the top of the mast, if it is a cabin that can also occupy a low position). The nacelle protection 17 is in the low position, and it is accessible from the rotating frame 4, by

  via a recipe platform 40.

  In this configuration, the crane operator accesses directly inside the nacelle 17 through the side door 29; it goes into the usual upward position of the lower scale 13, and initiates the rise of this

scale 13.

  As soon as the first rungs of the ladder 13 are climbed, the crane operator's shoulders rest under the harness 23 of the platform 17. Thus, continuing to climb normally on the ladder 13, the crane operator carries with him, by the intermediate of the harness 23, the nacelle 17 whose weight is compensated by the tensile force,

  directed upwards, exerted by the cable 34 of the winch 33.

  During this time, the cable 38 belonging to the immobilizing means 19 is automatically wound on the reel 37, to ensure the safety of movement of the nacelle 17 throughout its ascent, accompanying

  that of the crane operator, along the mast 5.

  The nacelle 17 moves first along the lower element 10 of the mast 5, the first pairs of rollers 26 and 27 ensuring its guidance and maintenance on the uprights 28 of the scale 13 associated with this lower element 10 When the nacelle 17 driven by the crane operator passes the passage of the lower mast element to the intermediate mast element 11, the second pair of rollers 26 and 27 take over the first pairs of rollers, ensuring the continuity of the guidance and

  the maintenance on the amounts 28 of the following scale 14.

  Similarly, when the nacelle 17 reached above crosses the passage of the intermediate mast element 11 to the upper mast element 12, the third pairs of rollers 26 and 27 intervene to ensure the continuity of the guidance and maintenance on the The nacelle 17 thus accompanies the crane operator, during the entire ascent of the mast 5, providing a lateral and dorsal protection, an intermediate position of the nacelle 17 being indicated on the

figure 2.

  Finally, the nacelle 17 arrives, with the crane operator, in its high position located at the cabin 16 - see Figures 3 and 4. The nacelle 17 is automatically locked in this high position, and the crane operator accesses directly inside of the cabin 16, whose door is in correspondence with the side door 29 of the nacelle 17, the relative provision of the cabin 16 and the nacelle 17 also appearing

clearly in Figure 6.

  Conversely, the crane operator descends from the crane with the protective basket 17, after having unlocked

manually said nacelle.

  To ensure proper operation, uphill and downhill, the harness 23 must always exert a force directed downwards and substantially constant, of the order of a few kilograms, on the shoulders of the crane operator. The value of this force is adjusted via the torque motor of the winch 33 for compensating the weight of the platform 17. In other words, the weight of the platform 17 must not be fully compensated, so that the harness 23 remains

  resting on the crane operator's shoulders.

  The device described above allows the crane operator, by locking the platform 17, to rest at any time during its upward or downward path along the mast 5, by placing itself on the floor 22. This device also allows the crane operator to intervene at any intermediate point of the path between the ground and the cabin 16, the floor 22 of the nacelle 17 then acting as a working platform. During such interventions, the harness 23 can be retracted to

  not to hinder the crane operator in his movements.

  In case of malaise of the crane operator, or technical incident resulting in the blocking of the nacelle protection 17 at a point far from the ground, the rescue or maintenance personnel can intervene to rescue the crane operator, using the scales 13, 14 , 15 of the mast 5 and individual safety equipment, access to the interior of the platform 17 being made possible

  in particular by the escape hatch 31.

  Figures 7 to 9 show another embodiment of the nacelle 17, in which the unmodified elements (with respect to the first embodiment) are designated by the same references, and will not be described again. In this second embodiment, the harness is replaced by a harness 41, composed of one or more straps tied to the rigid structure of the nacelle 17. Unlike the previous embodiment, the compensation means 18 exert here on the nacelle an upward effort which is greater than the own weight of the nacelle 17, so that the shoulder 41 permanently supports the crane operator. It is thus ensured that the nacelle 17 accompanies the crane operator during the climb or

the descent of the mast 5.

  Figures 10 and 11 show details of the scales 13, 14, 15 associated respectively with the three elements 10, 11, 12 of the telescopic mast 5. The scale 13 of the lower mast element 10 is located closest to the axis 3. The ladder 14 of the intermediate mast element 11 is shifted outwards, with respect to the previous ladder 13. The ladder 15 of the upper mast element 12 is itself outwardly offset from the previous ladder 14. The two ladders 14 and 15, other than the ladder 13 of the lower mast member 10, are rigidly secured only by their upper portion to the top of the corresponding mast element 11 or 12, via a pair of horizontal struts 42. In addition, the lower ends of the two ladders 14 and 15 are maintained and

  guided, respectively, on both scales 13 and 14.

  For this purpose, each scale 13, 14, 15 comprises, over its entire height, a vertical median rail 43, of section "T". The lower end of the upper ladder 15 is provided with a holding and guiding pad 44 engaged on the median rail 43 of the intermediate ladder 14. Similarly, the lower end of this intermediate ladder 14 is provided with a support and guide pad 45 engaged on the middle rail of

the lower scale 13.

  These arrangements allow the relative sliding of the three scales 13, 14, 15 accompanying the telescoping of the mast 5. Moreover, in relation with the device which is the subject of the present invention, they ensure that the ladders 13, 14, 15 with the required horizontal spacing, corresponding to the diameter of the rollers 26 and 27, between their respective uprights 28, which is necessary for the passage of the protective pod 17, from one ladder to the next or to the preceding, during the climb or descent of the crane operator. It goes without saying that the invention is not limited to only the modes of implementation of the method, and only the embodiments of the associated device, which have been described above, as examples; it embraces, on the contrary, all the variants of application and realization respecting the same principle. It is thus, in particular, that one would not depart from the scope of the invention by applying the method to access to driving stations, whether or not in the form of a cabin, always located in height but belonging to other lifting and handling equipment, such as harbor cranes, gantry cranes, overhead traveling cranes, etc., always provided with at least one mast or the like, also referred to as "leg" or "bent" ", equipped laterally

  one or more access ladders to the driving position.

  Nor would we depart from the scope of the invention by modifications of forms and constructive details, concerning the nacelle protection and its guidance along the mast of the crane or other lifting or handling equipment, or concerning the means of compensation of the weight of the nacelle and the immobilization means of said nacelle, or on the scales with their holding and guiding means, where the sliding pads can be replaced or

  supplemented by rolling means.

Claims (10)

  1 - Method for secure access to a high driving position, in particular on a tower crane, accessible by a mast or the like (5) in one or more parts (10, 11, 12) equipped laterally with one or more ladders (13, 14, 15) for access to a driving position or cabin (16), characterized in that it consists in using an individual protection device (17, 18, 19) movable along the mast ( 5), maintained and guided on the ladder or successively on the ladders (13, 14, 15) and driven by the crane operator on its path, when climbing along the ladder or ladders (13, 14, 15 ) to the cabin (16), and conversely when descending from the cabin (16).   2 - Method for secure access to a high driving position, according to claim 1, characterized in that the individual protection device (17, 18, 19) is driven along the mast (5) by the intermediate of a   harness (23) resting on the shoulders of the crane operator.   3 - Method for secure access to a high driving position, according to claim 1, characterized in that the individual protection device (17, 18, 19) is driven along the mast (5) by the intermediate of a shoulder belt (41) supporting the crane operator.   4 - Device for secure access to a high driving position, in particular on a tower crane, for the implementation of the method according to claim 2 or 3, characterized in that it comprises a personal protective nacelle (17 ), accessible from the outside, inside which the crane operator can stand, the nacelle (17) being provided with holding and guiding means (24, 25, 26, 27) on the ladder or scales ( 13, 14,) of the mast (5), and a harness (23) or harness (41) for its drive by the crane operator, the device further comprising means (18) for compensating the weight of the platform (17). and immobilization means (19) of said nacelle (17).   - Device for secure access to a high driving position, according to claim 4, characterized in that the nacelle protection (17) is in the form of a closed rigid structure but perforated, consisting of horizontal arches (20) joined by vertical rails (21), a floor (22) located at its base and having a platform function of rest or intervention and, possibly, a protective roof in its part upper (32).   6 - Device for secure access to a high driving position, according to claim 5, characterized in that the nacelle protection (17) is provided with a side access door (29), opening towards the interior, and an emergency hatch (31) formed in the floor (22). 7 Device for secure access to a substation   high pipe according to any of the claims   4 to 6, characterized in that the means for holding and guiding the protective nacelle (17) consist of pairs of rollers (26, 27) mounted in lines respectively on crosspieces (24, 25), symmetrically secured to on either side of the platform (17), on the one hand, at its lower part or floor (22) and, on the other hand, at an intermediate level between the lower part or floor (22) and the upper part (32) of the nacelle (17), the pairs of rollers (26, 27) bearing continuously on the uprights (28) of the ladder or ladders (13, 14, 15) of the mast (5).   8 - Device for secure access to a high driving position, according to claim 7, characterized in that free spaces, substantially equal to the thickness (e) of the uprights (28) of the ladders (13, 14, 15 ) of the mast, are formed between the different rows of rollers (26, 27), in correspondence with the different positions of the ladders (13, 14, 15) on successive mast elements (10, 11, 12), of different sections. the each other.   9 - Device for secure access to a substation   high pipe according to any of the claims   4 to 8, characterized in that the compensation means (18) of the weight of the protective nacelle (17) consist of a winch (33), equipped with a torque motor, fixed to the top of the mast (5), the cable (34) of the winch (33) descending above the nacelle (17) and being fixed at a point (35) located at the upper part (32) of said nacelle (17). - Device for secure access to a high driving position, according to any one of the   Claims 4 to 9, characterized in that the means   of immobilization (19) of the nacelle of protection (17)   consist of a winder (37) provided with an anti-winding device   chute operating by inertia, fixed at the top of the mast (5) substantially vertically above the nacelle (17), the cable (38) of the reel (37) being fixed at a point (39) located at the   upper part (32) of said nacelle (17).   11 - Device for secure access to a high driving position, according to any one of the   Claims 4 to 10, characterized by its application to   access to a cabin (16) of a self-erecting tower crane with a telescopic or folding mast (5) composed of successive mast elements (10, 11, 12) carrying respective ladders (13, 14, 15), on which is   maintained and guided the nacelle protection (17).   12 - Device for secure access to a high driving position on a tower crane, according to claim 11, characterized in that the cabin (16), to which this device gives access, is itself mobile along the mast (5) of the crane, and in particular guided on the same scales (13, 14, 15) as the nacelle protection (17).  13 - Device for secure access to a high driving position, on a telescopic tower tower crane according to claim 11 or 12, characterized in that the ladders (14, 15), other than the ladder (13) of the lower mast element (10), are rigidly fixed (at 42) only by their upper part to the top of the corresponding mast element (11, 12), the scales (13, 14, 15) being offset transversely relative to each other and having a medial rail (43) for holding and guiding the lower end of the ladder (14, 15) of the immediately upper mast element (11, 12) , this lower end being equipped with a rolling and / or sliding means (44, ) cooperating with the rail (43).