HOIST DEVICE FOR A SCAFFOLD
20170166426 · 2017-06-15
Inventors
- Jesper Ryberg Lonardi (Ringsted, DK)
- Michal Józef Leonhard (Gorzyce Wielkie, PL)
- Lukasz Józef Leonhard (Gorzyce Wielkie, PL)
- Szymon Józef Leonhard (Gorzyce Wielkie, PL)
Cpc classification
B66F11/04
PERFORMING OPERATIONS; TRANSPORTING
E04G1/24
FIXED CONSTRUCTIONS
E04G1/36
FIXED CONSTRUCTIONS
F16D63/006
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
E04G1/20
FIXED CONSTRUCTIONS
International classification
Abstract
A set of parts for providing a hoist (1, 101, 102) for a scaffold, the set of parts comprising a platform (2) adapted for carrying at least one object and comprising at least two gear elements (63, 64), the at least two gear elements being arranged at each of two opposing sides (25, 26) of the platform, two frames (31, 32) adapted for being arranged at each of the two opposing sides of the platform, the two frames each comprising one rack element (310, 320) arranged extending in a longitudinal direction (L) of the frame, and one motor (4) for moving the platform along a longitudinal direction of the two frames and for controlling the movement of the platform synchronously with respect to each of the two frames.
Claims
1. A set of parts for providing a hoist for a scaffold, the set of parts comprising: a platform adapted for carrying at least one object and comprising at least two gear elements, the at least two gear elements being arranged at each of two opposing sides of the platform, two frames adapted for being arranged at each of the two opposing sides of the platform, the two frames each comprising one rack element arranged extending in a longitudinal direction of the frame, and one motor for moving the platform along a longitudinal direction of the two frames and for controlling the movement of the platform synchronously with respect to each of the two frames, the rack element of each of the two frames comprising a toothed rack, and each of the gear elements of the platform comprising a gear, the toothed rack and the gear being adapted for mutual engagement, and wherein the rack element of each of the two frames comprises a first profile element adapted for accommodating the toothed rack, and each of the gear elements of the platform comprises a second profile element being adapted for accommodating the gear and for sliding engagement with one of the respective first profile elements.
2. A set of parts according to claim 1, wherein the motor is attached to the platform and wherein the platform further comprises a transmission element for driving each of the at least two gear elements, the transmission element extending from the motor and being connected to each of the at least two gear elements.
3. A set of parts according to claim 1, wherein the one rack element of each of the two frames is arranged centrally on the frame.
4. A set of parts according to claim 1, wherein at least one of the two frames comprise any one or more of: at least one longitudinal frame element arranged by a side of the rack element and extending substantially parallel with the rack element, and at least one transversal frame element extending substantially perpendicular to the rack element.
5. A set of parts according to claim 1, wherein the platform further comprises a compartment adapted for accommodating the motor, the compartment being arranged substantially centrally under the platform.
6. A set of parts according to claim 1, and further comprising a braking element adapted for braking the movement of the platform along the longitudinal direction of the two frames when the speed of the platform exceeds a predefined threshold, the braking element being of the type comprising a gear wheel with an internal brake mechanism.
7. A set of parts according to any one of the above claims, and further comprising any one or more of: a rail element adapted for enclosing the platform, at least one frame extension element adapted for connection with one of the two frames such as to extend the one of the two frames in the longitudinal direction, at least one first supporting element adapted for extending between the two frames, at least one second supporting element adapted for extending between one of the two frames and a base on which the two frames are arranged, and at least one wheel adapted for connection with one of the two frames and for rolling on a base on which the two frames are arranged.
8. A set of parts according to any one of the above claims, wherein the motor is arranged centrally under the platform.
9. A set of parts according to claim 1, wherein the transmission element is a transmission rod, the transmission rod being any one of one common rod and two separate rods.
10. A hoist for a scaffold built up of a set of parts according to any one of the above claims, the hoist comprising: a platform adapted for carrying at least one object and comprising at least two gear elements, the at least two gear elements being arranged at each of two opposing sides of the platform, two frames each comprising one rack element arranged extending in a longitudinal direction of the frame, the two frames being arranged at each of the two opposing sides of the platform such that the rack element of each of the at least two frames is in mutual engagement with at least one of the at least two gear elements, and one motor for moving the platform along a longitudinal direction of the two frames, the motor being connected to the at least two gear elements of the platform such as to control the movement of the platform synchronously with respect to each of the two frames.
11. A method for building up a hoist for a scaffold, the method comprising the steps of: providing a set of parts according to any one of claims 1-10, placing the two frames at each of two opposing sides of the platform such that the respective rack element of the two frames extend vertically, and arranging the platform such that the two gear elements of the platform are brought into engagement with the respective rack element of the two frames.
12. A set of parts according to claim 1, and further comprising a rail element adapted for enclosing the platform and comprising a door element which comprises a first part and a second part, the second part being arranged in the first part such as to be telescopically slidable with respect to the first part between a collapsed position and an extended position and the second part being biased towards the extended position with a biasing force of between 40 and 50 N.
Description
[0048] The invention will be described in more detail below by means of a non-limiting example of a presently preferred embodiment and with reference to the schematic drawings, in which:
[0049]
[0050]
[0051]
[0052]
[0053]
[0054]
[0055]
[0056]
[0057]
[0058] With reference to
[0059] An embodiment of a platform 2 is shown in
[0060] The platform 2 comprises a circumferential wall 21 and a plate 22. The plate 22 is provided with a lid 23, which may be any type of lid such as e.g. a hinged lid, a slidable lid or a snap-locking lid. The lid 23 forms an access to a compartment 24 for accommodating the motor 4. The platform 2 further comprises opposing sides 25 and 26 as well as opposing sides 27 and 28.
[0061] In the embodiment shown the platform 2 is rectangular in cross section. The platform 2 may, however, just as well have any other cross sectional shape such as square, polygonal, elliptic or circular. Hence, the term opposing sides as used herein is intended to refer both to two sides of the platform 2 extending parallel to one another as well as two diametrically opposite sides of a platform with e.g. an elliptic or circular cross section.
[0062] The platform 2 further comprises two gear elements 63 and 63. The two gear elements 63, 64 are arranged at each of the two opposing sides 25 and 26 of the platform 2 (cf.
[0063] An embodiment of a frame 31 is shown in
[0064] It is noted that the set of parts may also optionally comprise two or more frame extension elements 33, 34 (cf.
[0065] The frame 31 comprises one rack element 310 arranged extending in a longitudinal direction L of the frame 31 and centrally on the frame 31. The rack element 310 comprises a profile 314 and a toothed rack 315 (cf. also
[0066] The profile 314 is adapted for sliding engagement with a profile 630, 640 (cf.
[0067] The rack element 310 further comprises a first end 3101, which may or may not be closed off such as to prevent the platform from moving too far down towards the basis 9 (cf.
[0068] It is noted that in case of a frame extension element, both the first end and the second end of the rack element may be adapted for connection with the rack element of a further frame extension element. Alternatively, still in case of a frame extension element, the first end of the rack element may be adapted for being connected to the second end 3102 of the rack element 310 of the frame 31, whereas the second end of the rack element may be adapted for connection with the rack element of a further frame extension element.
[0069] The frame 31 further comprises two longitudinal frame elements 311 and 312 arranged by each side of and in a distance from the rack element 310 and extending substantially parallel with the rack element 310 and a plurality, as shown six, transversal frame elements 313 arranged substantially perpendicular to the rack element 310 and extending between the at least two longitudinal frame elements 311 and 312. Thereby a robust yet light-weight structure is provided. In other embodiments the longitudinal frame elements 311, 312 may be arranged adjacent to or in contact with the rack element 310.
[0070] The respective frames 31 and 32 as well as the respective frame extension elements 33 and 34, where applicable, are provided as one preassembled unit. Alternatively the longitudinal frame elements and/or the transversal frame elements may be provided as standard scaffolding elements comprising engagement ends for engagement with other standard scaffolding elements.
[0071] The two longitudinal frame elements 311 and 312 each comprise a first end 3111 and 3121, respectively, adapted for being placed directly on a basis 9 (cf.
[0072] It is noted that in case of a frame extension element, both the first ends and the second ends of the longitudinal frame elements of the frame extension element may be adapted for connection with the first ends of the longitudinal frame elements of a further frame extension element. Alternatively, and still in case of a frame extension element, the first ends of the longitudinal frame elements of the frame extension element are adapted for being connected to the second ends 3112, 3122 of the frame 31 (or 33 as the case may be), whereas the second ends of the longitudinal frame elements of the frame extension element are adapted for connection with a further frame extension element.
[0073] An embodiment of a motor 4 and a transmission 6 is shown in
[0074] The motor 4 controls the movement of the platform 2 synchronously with respect to each of the two frames 31, 32. As may be seen in
[0075] Furthermore a control device 41 for controlling the motor 4 is provided. The control device 41 may be connected to the motor 4 by means of a wired connection 42. Alternatively, the control device 41 may be connected to the motor by means of a wireless connection.
[0076] The transmission 6 comprises a transmission rod 61, 62 connecting the motor 4 with each of the gear elements 63 and 64. The transmission rod 61, 62 may be one common rod or two separate rods.
[0077] The gear elements 63 and 64 each comprise a gear 631 and 641, respectively, adapted for connection with a toothed rack 315, 325 of a rack element 310, 320 of a frame 31, 32.
[0078] The gear elements 63 and 64 further each comprise a profile 630 and 640, respectively, adapted for accommodating the respective gear 631 and 641 and for sliding engagement with a profile 314, 324 of a rack element 310, 320 of a frame 31, 32. The profiles 630, 640 are in the embodiment shown substantially U-shaped. In
[0079] The profiles 630, 640 are adapted for sliding engagement with a respective profile 310, 320 (cf.
[0080] The gear elements 63 and 64 further each comprise an in principle optional set of guiding elements 632-635 and 642-645, respectively, for guiding the gear elements 63, 64 on the rack elements 310, 320. In the embodiment shown the guiding elements 632-635 and 642-645 are wheels.
[0081] Turning now to
[0082] In an embodiment the substantially horizontally extending elements 52, 53 and the substantially vertically extending elements 51 are both provided as standard scaffolding elements comprising engagement ends for engagement with other standard scaffolding elements.
[0083] Turning now to
[0084] The first supporting elements 71 and 72 are both provided as standard scaffolding elements comprising a first engagement end 711 and 721, respectively, and a second engagement end 712 and 722, respectively, for engagement with the frame 31, 32. Such engagement ends, whether on a first supporting element or being similar engagement ends on any other element of a set of parts according to the invention, is known as such and may be made e.g. as described in WO 2010/136044 A1.
[0085] Turning now to
[0086] Furthermore, the set of parts may comprise one or more wheels 74, 75, 76, 77 (cf.
[0087] The wheels 74-77 and guiding wheels 631-635 and 641-645 are in an embodiment made of a suitably durable plastic or rubber material. The rack elements 310, 320, the gear elements 63, 64 and the transmission 6 are in an embodiment made of a suitable highly durable metal such as iron or steel. All other elements of the set of parts according to the invention are in an embodiment made of a robust yet lightweight material, e.g. a metal such as aluminium, for maximum strength and durability.
[0088] Turning to
[0089] Referring to
[0090] As may be seen, the gear elements 63 and 64 are brought into sliding engagement with the respective rack elements 310, 320 such as to enable the platform to move along a longitudinal direction L of the two frames.
[0091] As may also be seen, the platform 2 has been moved to the uppermost position at the top of the frames 31, 32 by operating the motor 4 by means of the control unit 41 to control the movement of the platform synchronously with respect to each of the two frames.
[0092]
[0093] Turning to
[0094] As may be seen the profiles 630 and 314 have been removed to show the toothed rack 315 and the gear 631, respectively, which are in mutual engagement.
[0095] As may furthermore be seen the toothed rack is attached to the horizontal frame elements 313 by means of attachment means 316 such as brackets. Likewise attachment means 317, such as brackets, used for attaching the profile 314 to the horizontal frame elements are shown.
[0096] Furthermore, the circumferential wall 21 of the platform 2 has been removed, such that the platform 2 now appears in its simplest form, namely a plate 22. A compartment 24 for accommodating the motor 4 is attached to the platform 2. The compartment 24 may comprise ventilation openings.
[0097] In a further embodiment, the platform 2 may comprise one or more intermediate walls arranged such that the transmission rods 61 or 62 extend through the intermediate walls. Such intermediate walls may add robustness to the structure of the platform 2 as well as help supporting the transmission rods 61 and 62.
[0098] Turning now to
[0099] In this embodiment the platform 2 forms a rung of the ladder-shaped hoist 101, while the frames 31 and 32 form the columns of the ladder-shaped hoist 101.
[0100] The platform 2 comprises two gear elements 63 and 64, e.g. of the type described above, the two gear elements 63 and 64 being arranged at each of two opposing sides of the platform 2 and the two frames 31 and 32 each comprising one rack element 310 and 320, e.g. of the type described above, respectively, arranged extending in a longitudinal direction of the frame and centrally on the frame.
[0101] The ladder-shaped hoist 101 further comprises a rail element 5, wheels 74 for easy transport of the ladder-shaped hoist 101 and a second supporting element 73.
[0102] Turning now to
[0103] The hoist 102 comprises a platform 2 and a rail element 5, the rail element 5 in this embodiment being a closed cage.
[0104] The hoist 102 further comprises two frames 31 and 32 arranged on opposing sides 25, 26 of the platform 2 as well as two frame extension elements 33 and 34 connected to the frames 31 and 32, respectively. The frames 31 and 32 as well as the frame extension elements 33 and 34, and thereby the hoist 102, are attached to a basis 9, here being a wall of a construction, e.g. the interior wall of a windmill tower, by means of suitable attachment means 318, 328, 338, 348.
[0105] The hoist 102 further comprises a plurality of first supporting elements 71, 72 for improved stability and durability of the hoist 102.
[0106] The platform 2 comprises two gear elements 63 and 64, e.g. of the type described above, the two gear elements 63 and 64 being arranged at each of two opposing sides of the platform 2 and the two frames 31 and 32 each comprising one rack element 310 and 320, e.g. of the type described above, respectively, arranged extending in a longitudinal direction of the frame and centrally on the frame. The two frame extension elements 33 and 34 likewise each comprise one rack element 330 and 340, respectively.
[0107] Turning now to
[0108] The door element 80 is in the embodiment shown adapted for forming a side of the rail 5. In principle the door element 80 may, however, just as well be used in any other suitable position on a scaffold in which a door element may be needed. Hence the door element 80 is a door element for a scaffold, and in particular a door element for a hoist for a scaffold according to the second aspect of the invention.
[0109] The door element 80 comprises a first part 81 and a second part 82, the second part 82 being arranged in the first part 81 such as to be telescopically slidable with respect to the first part 81 between a collapsed position and an extended position.
[0110] The first part 81 comprises at least two longitudinal elements 811, 812 and at least one transversal element 813 connecting the longitudinal elements 811, 812. The first part 81 is made of tubular elements. At least the longitudinal elements 811, 812 of the first part 81 may in one embodiment have an outer diameter of 50 mm.
[0111] The first part 81 comprises at least one engagement end 851, 852 adapted for engagement with another element of a hoist for a scaffold, particularly the rail 5, or another element of a scaffold, as the case may be.
[0112] The second part 82 comprises at least two longitudinal elements 821, 822 and at least one transversal element 823 connecting the longitudinal elements 821, 822. The second part 82 is made of tubular elements. At least the longitudinal elements 821, 822 of the second part 82 have an outer diameter corresponding to the inner diameter of the longitudinal elements 811, 812 of the first part 81.
[0113] The second part 82 comprises at least one abutment end 841, 842 adapted for abutment with another element of a hoist for a scaffold, particularly the rail 5, or another element of a scaffold, as the case may be.
[0114] The door element 80 further comprises a connection element 83 adapted for connection with another element of a hoist for a scaffold, for instance a suitable opening in the platform 2, or another element of a scaffold, as the case may be.
[0115] The second part 82 of the door element 80 is biased towards the extended position such as to keep the door closed, the biasing force being about 50 N, alternatively between 45 and 55 N or between 40 and 50 N.
[0116] With reference particularly to
[0117] The biasing device 86 is adapted for enabling the door element 80 to be opened by exerting a force which in one embodiment is about 50 N. In other embodiments the opening force may be between 45 and 55 N or between 40 and 50 N. Thereby the door element 80 is easy to open and it is simultaneously ensured that it is kept safely closed when not operated.
[0118] The biasing device 86 is arranged in one of the longitudinal elements 811, 812 of the first part 81 such as to be screened from dust, water and other potentially damaging external influences.
[0119] The biasing device 86 comprises in the embodiment shown a plurality of gas dampeners 871-876. In the embodiment shown the biasing device 86 comprises six gas dampeners 871-876, although another number of gas dampeners may alternatively be provided for. The gas dampeners 871-876 are connected in series or in other words end to end to form a line of gas dampeners. This provides for a simple biasing device with which the desired low opening force may be obtained over a relatively long distance, particularly distances exceeding 0200 mm. In comparison, a single actuator of any known type used as a biasing device 86 as shown on
[0120] Turning now to
[0121] The braking element 90 is a braking element for a hoist for a scaffold. The braking element 90 is adapted for braking the movement of the platform 2 along the longitudinal direction of the two frames 31, 32 when the speed of the platform 2 exceeds a predefined threshold. In one embodiment this threshold is set to 10 m/minute.
[0122] The braking element 90 has a construction similar to that of a toothed pulley. Particularly, the braking element 90 is of the type comprising a gear wheel with an internal brake mechanism
[0123] With reference particularly to
[0124] a fastening element 91 adapted for fastening the braking element 90 to the hoist, and particularly to the platform 2,
[0125] a connection element 92 adapted for connecting elements 92, 93, 94 and 96 of the braking element 90 to each other by means of attachment means such as bolts 921, screws, rivets or the like,
[0126] a sealing element 93, such as a ring-shaped gasket, adapted for sealing the braking element 90 such as to prevent dust, water and other potentially damaging external influences from entering the interior of the braking element 90,
[0127] a ring-shaped element 94 with an internal toothing,
[0128] a pawl element 95 adapted for engagement with the interior toothing of the ring-shaped element 94,
[0129] a gear wheel 96 adapted for engagement with the toothed rack 315, 325 of the rack element 310, 320 of one of the frames 31, 32,
[0130] a bearing element 97 adapted for ensuring that the gear wheel 96 may rotate freely when the braking element 90 is in its assembled state (
[0131] an optional safety spring element 98 for the bearing element 97. The fastening element 91 is attached fixedly to the connection element 92 by means of welding or the like.
[0132] The connection element 92 is more particularly adapted for connecting the sealing element 93 and the ring shaped element 94 fixedly or rigidly to the gear wheel 96.
[0133] The pawl element 95 is mounted on the gear wheel 96 by means of one attachment means in such a way that it is rotatable between a position in engagement with the interior toothing of the ring-shaped element 94 and a position out of engagement with the interior toothing of the ring-shaped element 94.
[0134] Elements 91, 92, 94, 95, 96 and 98 are made of a suitable metal such as iron or steel. The sealing element 93 is made of a suitable abrasion resistant material. The bearing element 97 is made of a material suitable for bearings, such as metal or plastic.
[0135] The braking element 90 is, by means of the fastening element 91 and suitable attachment elements such as screws, bolts, rivets or welds, mounted on the platform 2 in such a position that the gear wheel 96 is arranged in engagement with the toothed rack 315, 325 of the rack element 310, 320 of one of the frames 31, 32.
[0136] If the platform 2 and thereby the gear wheel 96 moves at a speed exceeding 10 m/minute, the pawl element 95 is automatically brought into engagement with the interior toothing of the ring-shaped element 94 by the centrifugal force exerted by the gear wheel 96 on the pawl element 95. Thereby the gear wheel 96 is blocked due to the fixed or rigid connection between the ring-shaped element 94 and the gear wheel 96, which in turn causes a braking force to be exerted on the platform 2. Thus, the pawl element 95 and the ring shaped element 94 form an internal brake mechanism for the gear wheel 86.
[0137] Thus, the invention provides a set of parts for providing a hoist for a scaffold, as well as a hoist built up of such a set of parts, which is adapted for being built together with an existing scaffold by means of standard scaffold parts. Also, it is noted that the set of parts according to the invention may just as well be said to be a set of parts for providing a scaffold hoist.
[0138] In the following a method according to the third aspect of the invention will be described.
[0139] A hoist 1, 101, 102 for a scaffold according to the second aspect of the invention may be build up by means of a method comprising the steps of:
[0140] providing a set of parts according to the first aspect of the invention,
[0141] placing the two frames 31, 32 at each of two opposing sides 25, 26 or 27,28 of the platform 2 such that the respective rack element 310, 320 of the two frames 31, 32 extend substantially vertically, and
[0142] arranging the platform 2 such that the two gear elements 63, 64 of the platform 2 are brought into engagement with the respective rack element 310, 320 of the two frames 31, 32.
[0143] The method for building up a hoist 1, 101, 102 for a scaffold may furthermore comprise any one or more of the following steps, not necessarily performed in the order mentioned:
[0144] a step of controlling the movement of the platform 2 synchronously with respect to each of the two frames 31, 32 by means of the motor 4,
[0145] a step of providing at least one of the two frames 31, 32 with at least one longitudinal frame element 311, 312, 321, 322 arranged on a side of the rack element 310, 320 and extending substantially parallel with the rack element 310, 320,
[0146] a step of providing at least one of the two frames 31, 32 with at least one transversal frame element 313, 323 extending substantially perpendicular to the rack element 310, 320,
[0147] a step of providing the hoist 1, 101, 102 with a transmission element 61, 62 extending from the motor 4 to each of the two frames 31, 32,
[0148] a step of arranging the motor 4 substantially centrally under the platform 2,
[0149] a step of providing the platform 2 with a compartment 24 adapted for accommodating the motor 4, arranging the compartment 24 substantially centrally under the platform 2 and arranging the motor 4 in the compartment 24,
[0150] a step of providing the rack element 310, 320 of each of the two frames 31, 32 with a toothed rack 315, 325, and providing each of the gear elements 63, 64 of the platform with a gear 631, 641, the toothed rack 315, 325 and the gear 631, 641 being adapted for mutual engagement, and
[0151] a step of providing the rack element 310, 320 of each of the two frames 31, 32 with a first profile element 314, 324 adapted for accommodating the toothed rack 315, 325, and providing each of the gear elements 63, 64 of the platform with a second profile element 630, 640 being adapted for accommodating the gear 631, 641 and for sliding engagement with one of the respective first profile elements 314, 324.
[0152] The method for building up a hoist 1, 101, 102 for a scaffold may furthermore comprise a step of providing at least one frame extension element 33, 34 adapted for connection with one of the two frames 31, 32 such as to extend the one of the two frames 31, 32 in the longitudinal direction, and a step of connecting the at least one frame extension element 33, 34 with one of the frames 31, 32.
[0153] The method for building up a hoist 1, 101, 102 for a scaffold may furthermore comprise a step of providing a rail element 5 adapted for enclosing the platform 2 and a step of arranging the rail element 5 on the platform 2.
[0154] The method for building up a hoist 1, 101, 102 for a scaffold may furthermore comprise a step of providing at least one first supporting element 71, 72 adapted for extending between the two frames 31 and 32 and a step of attaching the at least one first supporting element 71, 72 between the two frames 31 and 32.
[0155] The method for building up a hoist 1, 101, 102 for a scaffold may furthermore comprise a step of providing at least one second supporting element 73 adapted for extending between one of the two frames 31, 32 and a base 9 on which the two frames 31, 32 are arranged and a step of arranging the at least one second supporting element 73 such that one end is attached to one of the two frames 31 and 32 and another end is abutting the basis 9.
[0156] The method for building up a hoist 1, 101, 102 for a scaffold may furthermore comprise a step of providing at least one wheel 74, 75, 76, 77 adapted for connection with one of the two frames 31, 32 and for rolling on a base 9 on which the two frames 31, 32 are arranged and a step of connecting the at least one wheel 74, 75, 76, 77 to one of the two frames 31 and 32.
[0157] The method for building up a hoist 1, 101, 102 for a scaffold may furthermore comprise the step of providing a braking element 90 adapted for braking the movement of the platform 2 along the longitudinal direction L of the two frames when the speed of the platform 2 exceeds a predefined threshold, the braking element being of the type comprising a gear wheel 96 with an internal brake mechanism 94, 95, and a step of connecting the braking element 90 to the platform 2 in such a way that the gear wheel 96 of the braking element 90 is in engagement with the toothed rack 314, 324 of the rack element 310, 320 of one of the frames 31 and 32.
[0158] The method for building up a hoist 1, 101, 102 for a scaffold may furthermore comprise the step of providing a door element 80 which comprises a first part 81 and a second part 82, the second part 82 being arranged in the first part 81 such as to be telescopically slidable with respect to the first part 81 between a collapsed position and an extended position and the second part 82 being biased towards the extended position with a biasing force of between 40 and 50 N, and a step or arranging the door element 80 on the platform 2 as a part of a rail element 5.
[0159] It should be noted that the above description of preferred embodiments serves only as examples, and that a person skilled in the art will know that numerous variations are possible without deviating from the scope of the claims.