Ceiling unit lifting device and lifting method suitable for high and large space lobby

Abstract

The application discloses a suspended ceiling unit lifting device suitable for a high and large space hall and a lifting method thereof. Multiple I-shaped steel beams are connected at the bottom of a hall ceiling in rows and at intervals, installation spaces for installing suspended ceiling units are formed between two adjacent I-shaped steel beams, the suspended ceiling unit lifting device comprises a movable hoisting platform for carrying the suspended ceiling unit, the hoisting platform is located directly below the installation space, and a group of lifting points are arranged on opposite sides of the top of the hoisting platform; two groups of fixed pulleys are detachably connected at the bottom of the I-shaped steel beams located on the two sides of the installation space and are arranged in one-to-one correspondence with the two groups of lifting points; and two groups of lifting systems are arranged on the ground in one-to-one correspondence with the two groups of fixed pulleys, the lifting system comprises a steel wire rope which can be wound, one end of the steel wire rope is wound around the corresponding fixed pulley and is connected with the corresponding lifting point, and the construction efficiency is improved through the suspended ceiling unit lifting device.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, and in particular to a ceiling unit lifting device and lifting method suitable for high-ceilinged lobbies. Background Technology

[0002] In existing technologies, ceiling installation in high-ceilinged areas such as atriums and lobbies is typically carried out using full-scale scaffolding, requiring workers to perform high-altitude assembly work on the scaffolding. This method generally suffers from the following problems: Firstly, the erection and dismantling of full-scale scaffolding involves a huge amount of work, resulting in high material rental and labor costs, and a long construction period, severely impacting the overall project schedule. Secondly, the scaffolding covering the entire ground space prevents other work processes (such as floor paving, wall decoration, and electromechanical installation) from being carried out simultaneously, leading to idle work surfaces and work stoppages, thus reducing overall construction efficiency. Furthermore, high-altitude assembly work requires high precision from workers, making it difficult to guarantee the flatness of ceiling panel joints and overall straightness, and posing significant safety risks associated with working at heights.

[0003] Therefore, it is necessary to provide a new technical solution to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a ceiling unit lifting device and its construction method suitable for high-ceilinged lobbies. Through the cooperation of the hoisting platform, fixed pulleys and lifting system, the ceiling unit is lifted to the design elevation after being assembled on the ground, thereby reducing the amount of high-altitude work, shortening the construction period, and providing conditions for parallel construction of other processes in the space.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is a ceiling unit lifting device suitable for high-ceilinged lobbies. Multiple I-beams are connected in rows at intervals at the bottom of the lobby ceiling, and an installation space for installing ceiling units is formed between adjacent I-beams. The ceiling unit lifting device includes: A movable hoisting platform is used to support the ceiling unit. The hoisting platform is located directly below the installation space, and a set of hoisting points is provided on each of the opposite sides of the top of the hoisting platform. Two sets of fixed pulleys are detachably connected to the bottom of the I-beams located on both sides of the installation space, and are set one-to-one with the two sets of lifting points; Two lifting systems are set on the ground and correspond one-to-one with the two sets of fixed pulleys. Each lifting system includes a retractable steel wire rope, one end of which is wound around the corresponding fixed pulley and connected to the corresponding lifting point.

[0006] The present invention is further improved for the ceiling unit lifting device applicable to high-ceilinged lobbies in that each set of the lifting points, each set of the fixed pulleys, and each set of the lifting system are two in number, and the lines connecting the four lifting points, the four fixed pulleys, and the four lifting systems respectively form rectangles, and the three rectangles are arranged concentrically.

[0007] A further improvement of this invention, applicable to the ceiling unit lifting device for high-ceilinged lobbies, is that the lifting platform includes: Four main beams form a rectangular frame, and the two sets of suspension points are respectively connected to the opposite sides of the rectangular frame; A grid-like secondary beam is connected to the inner perimeter of the rectangular frame; Multiple sets of omnidirectional wheels are connected at intervals to the bottom of the rectangular frame.

[0008] A further improvement of the present invention for the ceiling unit lifting device applicable to high-ceilinged lobbies is that the hoisting platform further includes multiple barrier columns, which are spaced apart and connected around the rectangular frame to limit the position of the ceiling unit placed on the hoisting platform.

[0009] A further improvement of this invention for the ceiling unit lifting device in high-ceilinged lobbies is that each of the fixed pulleys is connected to the corresponding I-beam via a clamp. The clamp includes two C-shaped plates arranged opposite each other. The two C-shaped plates are respectively clamped on opposite sides of the lower flange plate of the I-beam and limited by a connector. The lower flange plates of the two C-shaped plates extend downward to form two extension sections. A rotating shaft is connected between the two extension sections, and the fixed pulley is rotatably connected to the rotating shaft.

[0010] A further improvement of the present invention for the ceiling unit lifting device of a high-ceilinged lobby is that the connecting member includes a limiting bolt, which is connected to the upper flange of each C-shaped plate and abuts against the top surface of the lower flange of the I-beam. In the connected state of the limiting bolt, the lower flange of the C-shaped plate abuts against the bottom surface of the lower flange of the I-beam.

[0011] A further improvement of this invention, applicable to ceiling unit lifting devices in high-ceilinged lobbies, is that the lifting system comprises: A movable support platform; A winch connected to the top of the support platform, on which the wire rope is wound up; The counterweight is placed on top of the support platform and offset from the winch.

[0012] A method for lifting suspended ceiling units suitable for high-ceilinged lobbies includes the following steps: Step 1: Provide the above-mentioned ceiling unit lifting device suitable for high-ceilinged lobbies; Step 2: Move the hoisting platform directly below the installation space and assemble the hoisting unit on the hoisting platform; Step 3: Pass the wire ropes in each lifting system around the corresponding fixed pulleys and connect each wire rope to the corresponding lifting point of the hoisting platform; Step 4: Synchronously control each group of the lifting system to rewind the corresponding wire rope, so that the hoisting platform drives the ceiling unit to be lifted upward along the installation space; Step 5: After the ceiling unit is raised to the preset installation position, the ceiling unit is fixedly connected to the bottom structure of the lobby ceiling, and the corresponding steel wire rope of each lifting system is released simultaneously to lower the hoisting platform.

[0013] Compared with the prior art, the advantages of the present invention are: 1. By using a hoisting platform to assemble the ceiling units on the ground, and then using fixed pulleys and a lifting system to lift the ceiling units to the design elevation, the ceiling installation has been transformed from high-altitude assembly to ground prefabrication and overall lifting, which greatly reduces the amount of high-altitude work, lowers safety risks, and improves construction efficiency. 2. By adopting a method of four lifting points, four fixed pulleys and four lifting systems arranged in a concentric rectangle, the lifting platform is subjected to uniform force and runs smoothly during the lifting process, avoiding platform tilting or jamming caused by eccentric loading, and ensuring the positioning accuracy of the ceiling unit. 3. By using clamps to detachably connect the fixed pulley to the bottom of the I-beam, welding work on the steel beam is eliminated, which not only protects the original structure but also enables the fixed pulley to be quickly installed, removed, and reused, thus reducing construction costs. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a front view of the ceiling unit lifting device of the present invention, applicable to high-ceilinged lobbies, in use.

[0016] Figure 2 This is a top view of the ceiling unit lifting device of the present invention, applicable to high-ceilinged lobbies.

[0017] Figure 3This is a top view of the hoisting platform of the ceiling unit lifting device of the present invention, applicable to high-ceilinged lobbies.

[0018] Figure 4 This is a front view of the hoisting platform of the ceiling unit lifting device applicable to high-ceilinged lobbies according to the present invention.

[0019] Figure 5 This is a detailed drawing of the fixed pulley connection of the ceiling unit lifting device of the present invention, applicable to high-ceilinged lobbies.

[0020] Figure 6 This is a top view of the lifting system of the ceiling unit lifting device applicable to high-ceilinged lobbies according to the present invention.

[0021] Figure 7 This is a front view of the lifting system of the ceiling unit lifting device of the present invention, applicable to high-ceilinged lobbies.

[0022] In the diagram: 1. Lifting platform; 101. Rectangular frame; 102. Grid-like secondary beam; 103. Barrier column; 104. Lifting point; 105. Universal wheel assembly; 2. Ceiling unit; 3. I-beam; 4. Clamp; 401. C-shaped plate; 402. Extension section; 403. Rotating shaft; 404. Limit bolt; 5. Fixed pulley; 6. Wire rope; 7. Lifting system; 701. Support platform; 702. Winch; 703. Limit column; 704. Counterweight. Detailed Implementation

[0023] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0024] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a more comprehensive overview of the ceiling unit lifting device and its lifting method applicable to high-ceilinged lobbies of the present invention.

[0025] Please see Figures 1-7 As shown, a ceiling unit lifting device suitable for high-ceilinged lobbies has multiple I-beams 3 spaced apart in a row at the bottom of the lobby ceiling. An installation space for the ceiling unit 2 is formed between adjacent I-beams 3. The ceiling unit lifting device includes: A movable hoisting platform 1 is used to support the ceiling unit 2. The hoisting platform 1 is located directly below the installation space. A set of hoisting points 104 are provided on each of the opposite sides of the top of the hoisting platform 1. Two sets of fixed pulleys 5 are detachably connected to the bottom of the I-beam 3 located on both sides of the installation space, and are set one-to-one with the two sets of lifting points 104; Two sets of lifting systems 7 are set on the ground and correspond one-to-one with the two sets of fixed pulleys 5. Each lifting system 7 includes a retractable steel wire rope 6, one end of which is wound around the corresponding fixed pulley 5 and connected to the corresponding lifting point 104.

[0026] By detachably installing the fixed pulley 5 onto the existing I-beam 3 at the bottom of the lobby ceiling, the I-beam 3 serves as the lifting fulcrum. At the same time, the lifting system 7 is set up on the ground, and the steel wire rope 6 is connected to the hoisting platform 1 after passing around the fixed pulley 5. This allows the ceiling unit 2 to be assembled on the ground and then lifted as a whole to the installation position. Compared with the traditional high-altitude assembly method, this solution reduces the time spent working at heights, reduces the need for scaffolding, and improves the efficiency of large-space ceiling construction.

[0027] Specifically, the lifting point 104 includes lifting lugs that are welded around the perimeter of the lifting platform 1.

[0028] Preferably, there are two sets of each lifting point 104, each set of each fixed pulley 5, and each set of each lifting system 7. The lines connecting the four lifting points 104, the four fixed pulleys 5, and the four lifting systems 7 form rectangles, and the three rectangles are concentrically arranged.

[0029] By adopting a lifting structure with a four-point rectangular arrangement, the lifting platform 1 is subjected to more balanced forces during the lifting process, reducing the risk of tilting and swaying of the lifting platform 1 and the ceiling unit 2, and improving the stability of the ceiling unit 2 during the lifting process.

[0030] Specifically, such as Figures 1-2 As shown: the four lifting points 104 are respectively set at the four corners of the lifting platform 1, the four fixed pulleys 5 are respectively located directly above the four lifting points 104, and the four lifting systems 7 are respectively set in the ground areas corresponding to the four corners of the lifting platform 1, so that the lifting force generated by the lifting system 7 acts on the four corners of the lifting platform 1 respectively.

[0031] Preferably, the lifting platform 1 includes: Four main beams form a rectangular frame 101, and two sets of suspension points 104 are respectively connected to the opposite sides of the rectangular frame 101. A grid-like secondary beam 102 is connected to the inner periphery of the rectangular frame 101; Multiple sets of omnidirectional wheels 105 are connected at intervals to the bottom of the rectangular frame 101.

[0032] By connecting the lifting points 104 to the four sides of the rectangular frame 101, the lifting load can be evenly transferred to the lifting platform 1 through the main beam, reducing the risk of structural deformation caused by localized stress concentration.

[0033] Specifically, the caster wheel assembly 105 has a self-locking function.

[0034] By using the universal wheel set 105 with self-locking function, the hoisting platform 1 can maintain a stable position after being moved to the construction position, thereby improving the safety and reliability of the ceiling unit 2 during assembly and lifting.

[0035] Specifically, the top of the grid-like secondary beam 102 is treated with an anti-slip coating.

[0036] By applying an anti-slip treatment to the top of the grid-like secondary beam 102, the friction between the ceiling unit 2 and the hoisting platform 1 can be increased, reducing the risk of the ceiling unit 2 slipping relative to the hoisting platform 1 during movement or lifting, and improving the stability of the ceiling unit 2 during transportation and lifting.

[0037] Preferably, the hoisting platform 1 also includes multiple guard posts 103, which are spaced apart and connected around the rectangular frame 101 to limit the position of the ceiling unit 2 placed on the hoisting platform 1.

[0038] Specifically, the position of the barrier post 103 is adjustable. Each barrier post 103 is connected to the rectangular frame 101 or the grid-like secondary beam 102 by bolts. The rectangular frame 101 and the grid-like secondary beam 102 are provided with multiple connection holes for selective connection of the barrier post 103. The positions of multiple barrier posts 103 are adjusted according to the specifications of the ceiling unit 2 to prevent horizontal displacement of the ceiling unit 2.

[0039] By setting the barrier column 103 as an adjustable structure and providing multiple connection holes on the rectangular frame 101 and the grid-like secondary beam 102, the barrier column 103 can adjust its installation position according to the different specifications of the ceiling unit 2, thereby improving the adaptability of the hoisting platform 1 to ceiling units 2 of different sizes; at the same time, by limiting the circumferential movement of the ceiling unit 2 through the barrier column 103, the risk of horizontal displacement of the ceiling unit 2 during movement and lifting is reduced, and the stability during the hoisting process is improved.

[0040] Preferably, each of the fixed pulleys 5 is connected to the corresponding I-beam 3 via a clamp 4. The clamp 4 includes two C-shaped plates 401 arranged opposite each other. The two C-shaped plates 401 are respectively clamped on opposite sides of the lower flange plate of the I-beam 3 and limited by a connector. The lower flange plates of the two C-shaped plates 401 extend downward to form two extension sections 402. A rotating shaft 403 is connected between the two extension sections 402, and the fixed pulley 5 is rotatably connected to the rotating shaft 403.

[0041] By employing a clamp 4 comprising two opposing C-shaped plates 401, the clamp 4 can be secured to both sides of the lower flange of the I-beam 3 and clamped and fixed via connectors. This eliminates the need for drilling, welding, or other processing on the existing I-beam 3, thus enabling the installation of the fixed pulley 5. This avoids damage to the existing steel structure and improves the ease of installation and disassembly of the fixed pulley 5, facilitating the rapid deployment of the ceiling unit 2 lifting device at different construction locations.

[0042] Specifically, the rotating shaft 403 is a screw, and two nuts are connected to the screw to stop the two extension sections 402 on their opposite outer sides. The fixed pulley 5 is located between the two extension sections 402 and is sleeved on the screw.

[0043] By setting the screw in conjunction with two nuts, the two C-shaped plates 401 are connected to form a whole, and at the same time, it also serves as a limiting effect to prevent the two C-shaped plates 401 from separating from each other.

[0044] Preferably, the connector includes a limiting bolt 404, which is connected to the upper flange of each C-shaped plate 401 and abuts against the top surface of the lower flange of the I-beam 3. When the limiting bolt 404 is connected, the lower flange of the C-shaped plate 401 abuts against the bottom surface of the lower flange of the I-beam 3.

[0045] Specifically, the limiting bolt 404 is vertically inserted into the upper flange of the C-shaped plate 401, and the length of the limiting bolt 404 extending into the C-shaped plate 401 is adjusted by screwing so that the limiting bolt 404 abuts against the lower flange of the I-beam 3, thereby pressing the lower flange of the C-shaped plate 401 against the bottom surface of the lower flange of the I-beam 3, thus achieving a reliable connection between the clamp 4 and the I-beam 3.

[0046] The clamping state between the clamp 4 and the I-beam 3 can be changed by adjusting the limiting bolt 404, so that the clamp 4 can move and adjust along the length of the I-beam 3. After the position adjustment is completed, the limiting bolt 404 can be tightened again to achieve fixation. There is no need to remove the clamp 4 or reprocess the existing steel structure, which further improves the construction efficiency.

[0047] Specifically, anti-slip pads are connected to the bottom of the limiting bolt 404 and the top surface of the lower flange of the C-shaped plate 401.

[0048] By providing anti-slip pads at the bottom of the limiting bolt 404 and on the top surface of the lower flange of the C-shaped plate 401, flexible contact is formed between the limiting bolt 404 and the I-beam 3, and between the C-shaped plate 401 and the I-beam 3. This increases the friction between the clamp 4 and the I-beam 3, thereby reducing the risk of slippage of the clamp 4 when bearing lifting loads and improving the stability of the fixed pulley 5 after installation. At the same time, the anti-slip pads can prevent the limiting bolt 404 and the C-shaped plate 401 from directly contacting and damaging the surface of the I-beam 3.

[0049] Preferably, the lifting system 7 includes: 701 is a movable support platform. A winch 702 is connected to the top of the support platform 701, and the wire rope 6 is wound on the winch 702. The counterweight 704 is placed on top of the support platform 701 and is offset from the winch 702.

[0050] By setting the winch 702 on a movable support platform 701 and setting a counterweight 704 on the support platform 701 that is offset from the winch 702, the lifting system 7 can be moved and adjusted according to the construction location requirements. At the same time, the counterweight 704 is used to balance the overturning moment generated by the winch 702 during operation, thereby improving the stability and safety of the lifting system 7 during operation.

[0051] By setting the lifting system 7 on the ground in conjunction with the fixed pulley for hoisting, the position is flexible and adjustable, and it is highly practical. This avoids directly installing the winch 702 on the I-beam 3, reducing high-altitude operations and preventing damage to the I-beam 3.

[0052] Specifically, the bottom of the support platform 701 is connected to a self-locking wheel set.

[0053] Specifically, the top of the support platform 701 is connected with multiple limiting posts 703 at intervals, and each limiting post 703 is fitted with multiple counterweights 704.

[0054] By setting a limiting post 703 on the top of the support platform 701 and fitting the counterweight 704 onto the limiting post 703, the horizontal movement of the counterweight 704 can be restricted, thereby improving the stability of the lifting system 7 during operation. At the same time, by adjusting the number of counterweights 704 stacked, the counterweight weight can be adjusted according to different lifting conditions.

[0055] A method for lifting suspended ceiling units suitable for high-ceilinged lobbies includes the following steps: Step 1: Provide the above-mentioned ceiling unit lifting device suitable for high-ceilinged lobbies; Step 2: Move the hoisting platform 1 directly below the installation space and assemble the hoisting unit on the hoisting platform 1; Step 3: Pass the wire rope 6 in each lifting system 7 around the corresponding fixed pulley 5, and connect each wire rope 6 to the corresponding lifting point 104 of the hoisting platform 1; Step 4: Synchronously control each group of the lifting system 7 to rewind the corresponding steel wire rope 6, so that the hoisting platform 1 drives the ceiling unit 2 to be lifted upward along the installation space; Step 5: After the ceiling unit 2 is raised to the preset installation position, the ceiling unit 2 is fixedly connected to the bottom structure of the lobby ceiling, and each lifting system 7 is controlled to release the corresponding steel wire rope 6 simultaneously, so that the hoisting platform 1 is lowered.

[0056] It should be noted that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A ceiling unit lifting device suitable for high-ceilinged lobbies, wherein multiple I-beams are connected in a row at intervals at the bottom of the lobby ceiling, and an installation space for installing the ceiling unit is formed between two adjacent I-beams, characterized in that, The ceiling unit lifting device includes: A movable hoisting platform is used to support the ceiling unit. The hoisting platform is located directly below the installation space, and a set of hoisting points is provided on each of the opposite sides of the top of the hoisting platform. Two sets of fixed pulleys are detachably connected to the bottom of the I-beams located on both sides of the installation space, and are set one-to-one with the two sets of lifting points; Two lifting systems are set on the ground and correspond one-to-one with the two sets of fixed pulleys. Each lifting system includes a retractable steel wire rope, one end of which is wound around the corresponding fixed pulley and connected to the corresponding lifting point.

2. The ceiling unit lifting device for high-ceilinged lobbies as described in claim 1, characterized in that, The number of each set of lifting points, each set of fixed pulleys, and each set of lifting systems is two. The lines connecting the four lifting points, the four fixed pulleys, and the four lifting systems respectively form rectangles, and the three rectangles are concentrically arranged.

3. The ceiling unit lifting device for high-ceilinged lobbies as described in claim 1, characterized in that, The hoisting platform includes: Four main beams form a rectangular frame, and the two sets of suspension points are respectively connected to the opposite sides of the rectangular frame; A grid-like secondary beam is connected to the inner perimeter of the rectangular frame; Multiple sets of omnidirectional wheels are connected at intervals to the bottom of the rectangular frame.

4. The ceiling unit lifting device suitable for high-ceilinged lobbies as described in claim 3, characterized in that, The hoisting platform also includes multiple retaining columns, which are spaced apart and connected around the rectangular frame to limit the position of the ceiling unit placed on the hoisting platform.

5. The ceiling unit lifting device suitable for high-ceilinged lobbies as described in claim 2, characterized in that, Each of the fixed pulleys is connected to the corresponding I-beam via a clamp. The clamp includes two C-shaped plates arranged opposite each other. The two C-shaped plates are respectively clamped on opposite sides of the lower flange plate of the I-beam and limited by a connector. The lower flange plates of the two C-shaped plates extend downward to form two extension sections. A rotating shaft is connected between the two extension sections, and the fixed pulley is rotatably connected to the rotating shaft.

6. The ceiling unit lifting device for high-ceilinged lobbies as described in claim 5, characterized in that, The connector includes a limiting bolt, which is connected to the upper flange of each C-shaped plate and abuts against the top surface of the lower flange of the I-beam. When the limiting bolt is connected, the lower flange of the C-shaped plate abuts against the bottom surface of the lower flange of the I-beam.

7. The ceiling unit lifting device for high-ceilinged lobbies as described in claim 1, characterized in that, The lifting system includes: A movable support platform; A winch connected to the top of the support platform, on which the wire rope is wound up; The counterweight is placed on top of the support platform and offset from the winch.

8. A method for lifting ceiling units suitable for high-ceilinged lobbies, characterized in that, Including the following steps: Step 1: Provide a ceiling unit lifting device as described in claim 1, suitable for high-ceilinged lobbies; Step 2: Move the hoisting platform directly below the installation space and assemble the hoisting unit on the hoisting platform; Step 3: Pass the wire ropes in each lifting system around the corresponding fixed pulleys and connect each wire rope to the corresponding lifting point of the hoisting platform; Step 4: Synchronously control each group of the lifting system to rewind the corresponding wire rope, so that the hoisting platform drives the ceiling unit to be lifted upward along the installation space; Step 5: After the ceiling unit is raised to the preset installation position, the ceiling unit is fixedly connected to the bottom structure of the lobby ceiling, and the corresponding steel wire rope of each lifting system is released simultaneously to lower the hoisting platform.

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