A caisson pressure lifting and sinking control device and method

Abstract

The application discloses a caisson pressure-lifting sinking control device and method, and relates to the technical field of caisson construction. The caisson pressure-lifting sinking control device comprises a supporting assembly, a pressure-lifting assembly for controlling sinking of a caisson segment is arranged on the supporting assembly; the pressure-lifting assembly comprises a downward pressing mechanism for pressing down the caisson segment and a lifting mechanism for lifting the caisson segment. The application can realize active adjustment of sinking timing, single sinking amplitude and sinking speed of caisson construction, changes sinking of the caisson from an uncontrolled mode to a controlled mode, improves sinking precision and safety of the caisson, and reduces engineering risk.

Description

Technical Field

[0001] This application relates to the field of caisson construction technology, specifically to a caisson pressure lifting and sinking control device and method. Background Technology

[0002] The construction of municipal pipelines is an important part of urban infrastructure construction. With the deepening of urbanization, there are more and more deep underground pipeline projects constructed using the cut-and-cover method.

[0003] The construction of underground pipelines sometimes involves as many as a hundred working shafts. Due to the limited construction space in cities, in order to reduce the land area occupied during construction, the vast majority of working shafts for underground pipeline construction are currently constructed using the caisson construction technique.

[0004] However, caissons are prone to tilting during the sinking process. They are difficult to sink when they encounter hard strata, and they may sink suddenly when they encounter soft strata. This not only affects the construction efficiency, but also poses a significant safety hazard to the caisson construction. Summary of the Invention

[0005] The purpose of this application is to provide a caisson pressure lifting and sinking control device and method to solve the problem of significant safety hazards in caisson construction.

[0006] The technical solution adopted by this application to solve its technical problem is:

[0007] In a first aspect, a caisson pressing and sinking control device is provided, including a support assembly, on which a pressing assembly for controlling the sinking of caisson segments is provided; the pressing assembly includes a pressing mechanism for pressing down the caisson segments and a lifting mechanism for lifting the caisson segments.

[0008] Furthermore, the support assembly includes a base, a support frame, a movable arm, a lifting cylinder, and a lifting beam; the support frame is fixed on the base, the movable arm is inclined from top to bottom and slidably mounted on the support frame along its axial direction, the lifting cylinder is disposed between the support frame and the movable arm and is used to drive the movable arm to move along its axial direction; the lifting beam is fixed to the upper end of the movable arm, and the lifting assembly is disposed on the lifting beam.

[0009] Furthermore, the support frame includes two spaced-apart side frames, the lower ends of which are connected to the base; the movable arms include two parallel ones, each of which is slidably connected to one of the two side frames, and the upper ends of which are fixedly connected to the lifting beam.

[0010] Furthermore, the lifting cylinder comprises two cylinders arranged in parallel.

[0011] Furthermore, the support frame also includes a connecting beam fixed between the two side frames.

[0012] Furthermore, the pressing mechanism includes a pressure plate disposed below the lifting beam and a pressing cylinder connected between the lifting beam and the pressure plate.

[0013] Furthermore, the lifting mechanism includes a winding assembly, a lifting cable, a lifting clamp, and a lifting pulley; the lifting pulley is disposed on the lifting beam, the first end of the lifting cable is connected to the lifting clamp, the second end of the lifting cable passes around the lifting pulley and is connected to the winding assembly, and the winding assembly is disposed on the base or the support frame and is used to wind up or release the lifting cable.

[0014] Furthermore, the lifting caliper includes a caliper seat for connecting to the first end of the lifting cable. Two opposing and downwardly extending caliper arms are hinged to the caliper seat. A caliper chuck is provided on the inner side of the lower end of each caliper arm. A caliper cylinder is provided between the caliper arm and the caliper seat. The caliper cylinder is used to drive the caliper arm to rotate around its hinged position with the caliper seat.

[0015] Furthermore, the lifting mechanism includes two parts, which are respectively disposed on both sides of the pressing mechanism.

[0016] Secondly, a method for controlling the lifting and lowering of a caisson is provided, comprising: constructing a guide ring beam at the construction location of the vertical shaft; providing a plurality of the aforementioned caisson lifting and lowering control devices and fixing a plurality of support components on the guide ring beam; hoisting the caisson segments to the construction location, connecting the lifting mechanism to the caisson segments, abutting the pressing mechanism against the top of the caisson segments, and lowering the caisson segments into place through the cooperation of the pressing mechanism and the lifting mechanism.

[0017] The beneficial effects of this application are:

[0018] The caisson sinking control device and method provided in this application utilize a pressure-lifting assembly consisting of a pressure-lifting mechanism and a lifting mechanism to sink caisson segments. When encountering hard strata, the pressure-lifting mechanism applies downward pressure to the caisson segments, reducing the sinking difficulty. When encountering soft strata, the lifting mechanism applies lifting force to the caisson segments, preventing sudden sinking or tilting and improving the safety of caisson sinking. Therefore, this application enables active adjustment of the sinking timing, single sinking amplitude, and sinking speed during caisson construction, transforming caisson sinking from an uncontrollable to a controllable mode, improving the accuracy and safety of caisson sinking, and reducing engineering risks. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a site layout diagram for the caisson sinking construction;

[0021] Figure 2 This is a schematic diagram of the caisson pressure lifting and sinking control device provided in the embodiments of this application;

[0022] Figure 3 This is a schematic diagram of the lifting caliper.

[0023] Figure label:

[0024] 1-Supporting components;

[0025] 11-Base;

[0026] 12-Support frame; 121-Side frame; 122-Connecting beam;

[0027] 13-Moving arm;

[0028] 14- Lifting cylinder;

[0029] 15-Lifting crossbeam;

[0030] 16 - Lifting cylinder pin;

[0031] 2-Pressing mechanism;

[0032] 21-Pressure plate;

[0033] 22- Downward pressure cylinder;

[0034] 3-Lifting mechanism;

[0035] 31-Rewinding assembly;

[0036] 32-Pulling cable;

[0037] 33-Lifting caliper; 331-Caliper base; 332-Caliper arm; 333-Caliper chuck; 334-Caliper cylinder; 335-Caliper base pin; 336-Caliper arm pin; 337-Caliper cylinder pin;

[0038] 34-Lifting pulley;

[0039] 4-Caison segments;

[0040] 41-Circumferential slot;

[0041] 5-Guide ring beam. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0043] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the embodiments and features described in these embodiments can be combined with each other unless otherwise specified.

[0044] In the description of the embodiments of this application, the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this application is usually placed during use, or the orientation or positional relationship commonly understood by those skilled in the art. The terms "set", "open", "installed", "connected", and "connected" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, and integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0045] See Figure 1 The present application provides a caisson pressing and sinking control device, which includes a support component 1 and a pressing component for controlling the sinking of the caisson segment 4. The pressing component includes a pressing mechanism 2 for pressing down the caisson segment 4 and a lifting mechanism 3 for lifting the caisson segment 4.

[0046] This application provides a method for controlling the sinking of a caisson by pressure increase, comprising the following steps:

[0047] S1. Construct guide ring beam 5 at the construction location of the vertical shaft.

[0048] Before the construction of the caisson, a guide ring beam 5 made of reinforced concrete is made at the construction location of the vertical shaft. When making the guide ring beam 5, anchor bolts need to be embedded in fixed positions according to the design.

[0049] S2. Provide several caisson pressure lifting and sinking control devices, and fix several support components 1 on the guide ring beam 5.

[0050] Several caisson pressure-lifting and sinking control devices can be assembled as a whole in the factory. After assembly, they are transported to the construction site by transport vehicles, and then hoisted into place on the guide ring beam 5 by hoisting equipment. The support components 1 of the caisson pressure-lifting and sinking control devices are then fixed to the guide ring beam 5 using anchor bolts. The number of caisson pressure-lifting and sinking control devices should be calculated based on the downward pressure and upward pulling force, and arranged reasonably. For example, the number of caisson pressure-lifting and sinking control devices should not be less than three sets, and they should preferably be arranged symmetrically or centrally symmetrically to avoid equipment overturning during the sinking construction process.

[0051] S3. Hoist the caisson segment 4 to the construction position, connect the lifting mechanism 3 to the caisson segment 4, and abut the pressing mechanism 2 against the top of the caisson segment 4. Through the cooperation of the pressing mechanism 2 and the lifting mechanism 3, the caisson segment 4 is lowered into place.

[0052] The construction of the caisson mainly includes caisson excavation and caisson sinking, which are carried out alternately until the caisson construction reaches the designed depth. For example, conventional excavation equipment such as rotary drilling rigs, excavators, and grab buckets can be used for caisson excavation. The excavation depth is consistent with the height of the caisson segment 4. After the excavation of each section of the caisson is completed, the caisson sinking operation can be carried out. The pressing mechanism 2 can apply downward pressure to the caisson segment 4, and the lifting mechanism 3 can apply lifting force to the caisson segment 4. With the cooperation of the pressing mechanism 2 and the lifting mechanism 3, the caisson segment 4 can be sunk into place. After the caisson is sunk into place, the excavation operation of the next section of the caisson is repeated.

[0053] The caisson pressing and sinking control device and method provided in this application embodiment uses a pressing assembly consisting of a pressing mechanism 2 and a lifting mechanism 3 to sink the caisson segments 4. When encountering hard strata, the sinking force of the caisson may be insufficient. In this case, the pressing mechanism 2 can be used to apply downward pressure to the caisson segments to increase the sinking force and reduce the sinking difficulty. When encountering soft strata, the sinking force of the caisson may be excessive. In this case, the lifting mechanism 3 can be used to apply lifting force to the caisson segments 4 to slowly lower the caisson segments 4, so that the caisson sinks evenly and avoids sudden sinking. When the caisson's posture deviates, the downward pressure on the deviated side and the lifting force on the opposite side can be increased through the cooperation of several caisson pressing and sinking control devices to correct the deviation and improve the safety of the caisson sinking. Therefore, this application enables active adjustment of the sinking timing, single sinking amplitude, and sinking speed during caisson construction, transforming caisson sinking from an uncontrollable to a controllable mode, improving the accuracy and safety of caisson sinking, and reducing engineering risks.

[0054] The first section of the caisson segment 4 has a large sinking force during the caisson construction. In order to prevent the first section of the caisson segment 4 from sinking suddenly during the ring assembly process, a pad can be placed under the cutting edge to prevent the cutting edge from sinking. After the first section of the caisson segment 4 is hoisted into place to form a ring structure and the lifting mechanism 3 is connected to the caisson segment 4, the first section of the caisson segment 4 is lifted off the ground by the lifting mechanism 3 so that the pad under the cutting edge can be removed. After the pad is removed, the first section of the caisson segment 4 sinks into place as a whole under the cooperation of the pressing mechanism 2 and the lifting mechanism 3.

[0055] After the first section of the caisson segment 4 is lowered into place, the pressing mechanism 2 and the lifting mechanism 3 need to be reset, and the next section of the caisson segment 4 needs to be assembled. During the assembly of the next section of the caisson segment 4 into a ring, to prevent the previous section from suddenly sinking, a symmetrical or continuous operation mode can be used for resetting the pressing mechanism 2 and the lifting mechanism 3 and hoisting the next section of the caisson segment 4. This ensures that during the hoisting and ring-forming process, part of the lifting mechanism 3 continues to lift the previous section of the caisson segment 4, providing continuous lifting force. After the next section of the caisson segment 4 is assembled into a ring structure, it is then lowered into place as a whole with the cooperation of the pressing mechanism 2 and the lifting mechanism 3.

[0056] For example, see Figure 1 Each ring structure includes four caisson segments 4, and each caisson segment 4 is equipped with a caisson pressure lifting and sinking control device to... Figure 1 The four caisson lifting and lowering control devices configured in the middle are numbered 1#, 2#, 3#, and 4# sequentially along the circumference of the guide ring beam 5. After the previous section of caisson segment 4 is lowered into place, the lifting and lowering control devices 1# and 3# can be symmetrically reset first. After the caisson segment 4 corresponding to the lifting and lowering control devices 1# and 3# is hoisted into place, the lifting mechanism 3 in the lifting and lowering control devices 1# and 3# is connected to the corresponding caisson segment 4. Then the lifting and lowering control devices 2# and 4# are reset. After the caisson segment 4 corresponding to the lifting and lowering control devices 2# and 4# is hoisted into place, the lifting mechanism 3 in the lifting and lowering control devices 2# and 4# is connected to the corresponding caisson segment 4. After the next section of caisson segment 4 is assembled into a ring structure, it is lowered into place as a whole with the cooperation of the pressing mechanism 2 and the lifting mechanism 3.

[0057] Of course, in the above embodiments, the installation of the caisson segment 4 can also be completed in the sequential operation mode of the pressure lifting and sinking control device of caisson #1, #2, #3, and #4. After the caisson segment 4 is assembled into a ring structure, it is then sunk into place as a whole with the cooperation of the pressing mechanism 2 and the lifting mechanism 3.

[0058] In some embodiments, see Figure 2The support assembly 1 includes a base 11, a support frame 12, a movable arm 13, a lifting cylinder 14, and a lifting beam 15. The support frame 12 is fixed on the base 11. The movable arm 13 is inclined from top to bottom and slidably mounted on the support frame 12 along its axial direction. The lifting cylinder 14 is disposed between the support frame 12 and the movable arm 13 and is used to drive the movable arm 13 to move along its axial direction. The lifting beam 15 is fixed to the upper end of the movable arm 13, and the lifting assembly is disposed on the lifting beam 15.

[0059] For example, the base 11 is used to fix the guide ring beam 5 to the pre-embedded anchor bolts during construction; the base 11 can be a plate structure made of steel plate, or a frame structure spliced ​​from structural steel. The support frame 12 is a frame structure spliced ​​from structural steel. For example, see... Figure 1 The support frame 12 includes two spaced-apart side frames 121, each a frame structure assembled from steel sections, with its lower end connected to the base 11. The side frames 121 and base 11 can be reliably connected using bolts or welding. The support frame 12 also includes a connecting beam 122 fixed between the two side frames 121. The connecting beam 122 provides lateral reinforcement to the side frames 121, preventing lateral instability. The connecting beam 122 at the bottom can also be connected to the base 11, further improving the reliability of the support assembly 1. There can be one or two movable arms 13; when there are two movable arms 13, they are parallel and slidably connected to the two side frames 121 respectively, with their upper ends fixedly connected to the lifting beam 15. The two ends of the lifting cylinder 14 are connected to the support frame 12 and the lifting beam 15 respectively via lifting cylinder pins 16. There can be one or two lifting cylinders 14; when there are two lifting cylinders 14, the two lifting cylinders 14 are parallel, the upper ends of the two lifting cylinders 14 are connected to the lifting beam 15, and the lower ends of the two lifting cylinders 14 are respectively connected to the two side frames 121. The extension and retraction of the lifting cylinders 14 drives the movable arm 13 to reciprocate along its own axis, which in turn drives the lifting assembly to move in space through the lifting beam 15.

[0060] See Figure 1After the support assembly 1 is fixed on the guide ring beam 5, the movable arm 13 tilts from top to bottom in a direction away from the caisson segment 4. Since the movable arm 13 is at a certain angle to the ground, when the lifting cylinder 14 retracts and drives the movable arm 13 to move downward, the movable arm 13 not only drives the lifting assembly to move downward through the lifting beam 15, but also drives the lifting assembly to move away from the caisson segment 4 through the lifting beam 15, so that the lifting assembly moves from directly above the caisson segment 4 to the outside of the caisson segment 4, ensuring that there is enough space above the existing caisson segment 4 to avoid the hoisting operation of the subsequent caisson segment 4, so that the subsequent caisson segment 4 can be hoisted by simply moving up and down, reducing the difficulty of hoisting the subsequent caisson segment 4, reducing the hoisting time, and thus saving the caisson construction period. After the subsequent caisson segment 4 is installed in place, the lifting cylinder 14 extends and drives the movable arm 13 to move upward, which in turn drives the lifting component to move directly above the caisson segment 4 through the lifting beam 15. After connecting the lifting mechanism 3 with the caisson segment 4, the caisson segment 4 can be lowered into place as a whole with the cooperation of the pressing mechanism 2 and the lifting mechanism 3.

[0061] In some embodiments, see Figure 2 The pressing mechanism 2 includes a pressure plate 21 disposed below the lifting beam 15 and a pressing cylinder 22 connected between the lifting beam 15 and the pressure plate 21. For example, the pressing cylinder 22 is vertically arranged, its cylinder body is fixedly connected to the lifting beam 15, and its piston rod is fixedly connected to the pressure plate 21. The lifting mechanism 3 includes a winding assembly 31, a lifting cable 32, a lifting clamp 33, and a lifting pulley 34. The lifting pulley 34 is disposed on the lifting beam 15. The first end of the lifting cable 32 is connected to the lifting clamp 33, and the second end of the lifting cable 32 passes over the lifting pulley 34 and is connected to the winding assembly 31. The winding assembly 31 is disposed on the base 11 or the support frame 12 and is used to wind up or release the lifting cable 32. The winding assembly 31 can be a winch or a hoist, etc.

[0062] See Figure 1During the caisson sinking construction, the pressure plate 21 abuts against the top of the caisson segment 4, and the lifting clamp 33 is connected to the caisson segment 4. When encountering hard strata and insufficient sinking force, the pressure cylinder 22 extends, applying downward pressure to the caisson segment 4 through the pressure plate 21 to increase the sinking force of the caisson and allow it to continue sinking. During this process, the winding assembly 31 simultaneously releases the lifting cable 32, always maintaining the extension of the pressure cylinder 22 equal to the release length of the lifting cable 32. This reduces the difficulty of sinking the caisson in hard strata and improves sinking efficiency. When encountering soft strata and excessive sinking force, the pressure cylinder 22 retracts, and the lifting mechanism 3 provides lifting force to the caisson segment 4. The winding assembly 31 is controlled to release the lifting cable 32 at a preset speed to control the uniform sinking of the caisson segment 4. This avoids sudden sinking of the caisson in soft strata and improves the safety of the caisson sinking construction.

[0063] In some embodiments, see Figure 3 The lifting caliper 33 includes a caliper seat 331 for connecting to the first end of the lifting cable 32. Two opposing and downwardly extending caliper arms 332 are hinged on the caliper seat 331. A caliper chuck 333 is provided on the inner side of the lower end of the caliper arms 332. A caliper cylinder 334 is provided between the caliper arms 332 and the caliper seat 331. The caliper cylinder 334 is used to drive the caliper arms 332 to rotate around their hinged position with the caliper seat 331.

[0064] For example, a caliper seat pin 335 is horizontally arranged at the top of the caliper seat 331, and a lifting ring is provided at the first end of the lifting cable 32. By fitting the lifting ring onto the caliper seat pin 335, the caliper seat 331 is connected to the first end of the lifting cable 32. The upper end of the caliper arm 332 is hinged to the caliper seat 331 via a horizontally arranged caliper arm pin 336, allowing the caliper arm 332 to rotate around the caliper arm pin 336. The two ends of the caliper cylinder 334 are respectively hinged to the caliper seat 331 and the caliper arm 332 via caliper cylinder pins 337, wherein the caliper cylinder pin 337 is parallel to the caliper arm pin 336. During operation, by controlling the extension or retraction of the caliper cylinder 334, the caliper arm 332 can be driven to rotate around the caliper arm pin 336, thereby causing the two caliper jaws 333 to move closer or further apart. See Figure 1 Both the inner and outer arms of the caisson segment 4 are provided with circumferential grooves 41 or holes for cooperating with the caliper 333.

[0065] The connection process between the lifting clamp 33 and the caisson segment 4 is as follows: the winding assembly 31 releases the lifting cable 32, thereby lowering the lifting clamp 33. During this process, the clamp cylinder 334 is controlled to retract so that the two clamp heads 333 move away from each other until the distance between the two clamp heads 333 is greater than the thickness of the caisson segment 4. After the lifting clamp 33 is lowered to the predetermined position, the two clamp heads 333 are located on both sides of the caisson segment 4. The clamp cylinder 334 is controlled to extend so that the two clamp heads 333 move closer to each other and are engaged in the circumferential groove 41 to clamp the caisson segment 4, ensuring that the lifting clamp 33 and the caisson segment 4 are firmly connected together.

[0066] See Figure 1 , Figure 2 The lifting mechanism 3 includes two parts, which are respectively arranged on both sides of the pressing mechanism 2. Thus, the two lifting mechanisms 3 can apply a lifting force to the caisson segment 4 on both sides of the pressing mechanism 2, reducing the possibility of the caisson segment 4 tilting along its circumference and improving the stability and reliability of the sinking construction of the caisson segment 4.

[0067] The above description is merely a preferred embodiment of this application and is not intended to limit this application in any way. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments based on the technical essence of this application and within the spirit and principles of this application shall still fall within the protection scope of the technical solution of this application.

Claims

1. A caisson pressure-raising and sinking control device, characterized in that, Includes a support assembly (1), on which a pressure-lifting assembly for controlling the sinking of the caisson segment (4) is provided; The pressure-lifting assembly includes a pressing mechanism (2) for pressing down the caisson segment (4) and a lifting mechanism (3) for lifting the caisson segment (4). The support assembly (1) includes a base (11), a support frame (12), a movable arm (13), a lifting cylinder (14), and a lifting beam (15). The support frame (12) is fixed on the base (11), the movable arm (13) is inclined from top to bottom and slidably mounted on the support frame (12) along its axis, and the lifting cylinder (14) is disposed between the support frame (12) and the movable arm (13) and is used to drive the movable arm (13) to move along its axis; The lifting beam (15) is fixed to the upper end of the movable arm (13), and the lifting assembly is disposed on the lifting beam (15); The support frame (12) includes two spaced-apart side frames (121), the lower ends of which are connected to the base (11); The movable arm (13) includes two parallel ones, which are slidably connected to the two side frames (121) respectively, and the upper ends of the two movable arms (13) are fixedly connected to the lifting beam (15). The lifting cylinder (14) comprises two cylinders arranged in parallel. The support frame (12) also includes a connecting beam (122) fixed between the two side frames (121). The pressing mechanism (2) includes a pressure plate (21) disposed below the lifting beam (15) and a pressing cylinder (22) connected between the lifting beam (15) and the pressure plate (21). The lifting mechanism (3) includes a winding assembly (31), a lifting cable (32), a lifting clamp (33), and a lifting pulley (34). The lifting pulley (34) is mounted on the lifting beam (15). The first end of the lifting cable (32) is connected to the lifting clamp (33). The second end of the lifting cable (32) passes around the lifting pulley (34) and is connected to the winding assembly (31). The winding assembly (31) is mounted on the base (11) or the support frame (12) and is used to wind up or release the lifting cable (32). The lifting caliper (33) includes a caliper seat (331) for connecting to the first end of the lifting cable (32). Two opposing and downwardly extending caliper arms (332) are hinged on the caliper seat (331). A caliper chuck (333) is provided on the inner side of the lower end of the caliper arms (332). A caliper cylinder (334) is provided between the caliper arms (332) and the caliper seat (331). The caliper cylinder (334) is used to drive the caliper arms (332) to rotate around their hinged position with the caliper seat (331).

2. The caisson pressure-raising and sinking control device according to claim 1, characterized in that, The lifting mechanism (3) includes two parts, and the two lifting mechanisms (3) are respectively arranged on both sides of the pressing mechanism (2).

3. A method for controlling the sinking of a caisson under pressure, characterized in that, include: Construct a guide ring beam (5) at the construction location of the vertical shaft; provide several caisson lifting and sinking control devices as described in any one of claims 1 to 2, and fix several support components (1) on the guide ring beam (5); hoist the caisson segment (4) to the construction location, connect the lifting mechanism (3) to the caisson segment (4), and abut the top of the pressing mechanism (2) against the caisson segment (4), and sink the caisson segment (4) into place through the cooperation of the pressing mechanism (2) and the lifting mechanism (3).

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