Offshore small active-passive wave-compensated gallery bridge and working method thereof

Abstract

The application discloses a small offshore active-passive wave compensation gallery bridge and a working method thereof, which comprises a rotary base, a main bridge body and a front telescopic arm; the upper half of the rotary base is hinged with the main bridge body at the top, the inside of the main bridge body is fixed with a sliding guide rail, and the front telescopic arm is embeddedly connected on the sliding guide rail; a pitch hydraulic cylinder is hinged between the main bridge body and the rotary base; a telescopic hydraulic cylinder is installed in parallel between the main bridge body and the front telescopic arm; the front end of the front telescopic arm is connected with a terminal pile gripper, and the inside of the terminal pile gripper is installed with a mechanical locking mechanism and a mechanical forced pin pulling mechanism; one side of the rotary base is fixed with a square guide rail box, the inside of the square guide rail box is fixed with a vertical guide rail in the vertical direction, and a weight is slidingly connected on the vertical guide rail; a pressure maintaining self-locking release device is installed in the lower half area of the vertical guide rail.

Description

Technical Field

[0001] This invention belongs to the field of wave-compensated corridor bridges, and relates to a small-scale active and passive wave-compensated corridor bridge at sea and its working method. Background Technology

[0002] As offshore wind power expands into deeper waters, the operation and maintenance environment of wind farms is becoming increasingly harsh. Maintenance personnel face significant safety risks when boarding the severely rocking maintenance vessel to the fixed offshore wind turbine foundation (mooring pile). Currently, wave compensation gate bridges on the market are mainly divided into two categories: purely active compensation gate bridges and passive overlapping gate bridges. While purely active systems offer high docking accuracy, their control systems are extremely complex. The hydraulic system requires high-frequency, high-pressure operation throughout, resulting in enormous energy consumption and a high risk of failure due to prolonged high-load conditions. Passive gate bridges, although structurally simple, struggle to achieve precise docking in large waves, making them highly susceptible to accidents where the end of the bridge impacts the wind turbine foundation.

[0003] In addition, under extreme conditions such as a sudden power outage or complete failure of the hydraulic system, the existing boardwalks often get stuck on the wind turbine piles or fall freely without support, causing devastating damage to maintenance personnel and equipment. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a small active and passive wave compensation boarding bridge at sea and its working method, which greatly improves the safety of boarding at sea, the reliability of the equipment, and significantly reduces the maintenance cost throughout the entire life cycle.

[0005] To achieve the above objectives, the present invention employs the following technical solution: A small-scale active and passive wave-compensated corridor bridge for marine use includes a slewing base, a main bridge body, and a front telescopic boom. The upper half of the slewing base is hinged to the top of the main bridge body, and a sliding guide rail is fixed inside the main bridge body. The front telescopic arm is fitted and connected to the sliding guide rail. A pitching hydraulic cylinder is hinged between the main bridge body and the slewing base. A telescopic hydraulic cylinder is installed parallel between the main bridge body and the front telescopic arm. The front end of the front telescopic arm is connected to an end pile gripper, and a mechanical locking mechanism and a mechanical forced pin pulling mechanism are installed inside the end pile gripper. A square guide rail box is fixed on one side of the slewing base. A vertical guide rail is fixed inside the square guide rail box along the vertical direction. A counterweight is slidably connected on the vertical guide rail. A pressure-holding self-locking release device is installed in the lower half of the vertical guide rail. The pressure-holding self-locking release device includes a hydraulic component and a mechanical pawl. The top of the mechanical pawl is formed as a hook end. A concave lock is provided at the bottom of the counterweight to engage with the hook end. A steel wire rope is connected to the top center of the counterweight. A fixed pulley is installed on the top of the square guide box. The steel wire rope extends towards the main bridge body after passing around the fixed pulley and is divided into a release cable and a lifting cable. The end of the release cable passes through the housing of the end pile holder and is connected to the mechanical forced pin pulling mechanism. A lifting hinge point is fixed in the middle section of the main bridge body. The end of the lifting cable is connected to the lifting hinge point. The effective tension length of the release cable is shorter than the effective tension length of the lifting cable.

[0006] Optionally, the interior of the rotary base is designed as a closed cylindrical cavity, and a rotary drive motor is fixed on the bottom plate of the cylindrical cavity. The rotary drive motor has an output shaft that extends vertically upward, and a drive gear is connected to the end of the output shaft. The upper half of the slewing base is connected to the lower half via a slewing bearing. The inner ring of the slewing bearing is fixed to the lower half of the slewing base, and the outer ring of the slewing bearing is fixed to the upper half of the slewing base. An internal gear ring is machined on the inner side of the outer ring of the slewing bearing, and the drive gear meshes with the internal gear ring. The side wall of the rotating base is machined with a vibration-free mounting surface, and a high-frequency motion reference unit is fixed on the vibration-free mounting surface.

[0007] Optionally, the end-capsule has a clamping mechanism and a clamping cylinder installed inside. The output end of the clamping cylinder is connected to the clamping mechanism. The mechanical locking mechanism includes a locking pin, which is inserted into the locking hole of the clamping mechanism when locked. The mechanical forced pin pulling mechanism is equipped with a spring potential energy preload device, which abuts against the outside of the locking pin. A high-strength polyurethane buffer pad is fixed on the contact surface inside the opening of the end-end pile gripper; a pressure relay is connected in series in the hydraulic circuit of the clamping cylinder.

[0008] Optionally, the pressure-holding self-locking release device has a fixed base inside, and the bottom of the mechanical pawl is mounted on the fixed base via a hinge pin; The hydraulic assembly includes a hydraulic push rod arranged in parallel to the rear side of the mechanical pawl, the hydraulic push rod having a piston rod, the front end of the piston rod abutting against the force-bearing support surface on the back side of the mechanical pawl; The hydraulic push rod has a rodless cavity inside, and a helical return spring is sleeved inside the rodless cavity. The oil inlet of the hydraulic push rod is connected to the push rod oil pipe, which leads directly to the main oil supply circuit.

[0009] Optionally, a guide wheel assembly is fixed to the side wall of the main bridge body, and the unhooking cable extends along the guide wheel assembly to the front end of the housing of the end pile gripper; A guide groove is provided at the top of the main bridge body, and the lifting cable extends along the guide groove to the lifting hinge point of the main bridge body.

[0010] Optionally, both the pitch hydraulic cylinder and the telescopic hydraulic cylinder include a rod chamber and a rodless chamber, and a large-diameter two-position two-way solenoid unloading valve is connected in parallel between the inlet and outlet ports of the rod chamber and the inlet and outlet ports of the rodless chamber of the pitch hydraulic cylinder and the telescopic hydraulic cylinder. The first port of the large-diameter two-position two-way electromagnetic unloading valve is connected to the oil circuit of the rodless chamber, and the second port is connected to the oil circuit of the rod chamber. Both the pitching and telescopic hydraulic cylinders have magnetostrictive displacement sensors built into their cylinder barrels.

[0011] Optionally, the main bridge body is a rectangular truss structure, which is welded together from multiple longitudinal main chord members and multiple transverse and diagonal web members; A low-friction slider is fixed on the outer wall of the front telescopic arm, and the slider is fitted inside the sliding guide rail.

[0012] Optionally, the square guide rail box is a hollow column structure with a rectangular cross-section, and the outer layer of the square guide rail box is wrapped with a protective shell; The weight is cylindrical in shape, with a sliding guide block fixed on the side of the weight. A groove is opened in the vertical guide rail, and the sliding guide block is fitted into the groove. The weight is suspended in the upper part of the square guide rail box.

[0013] Optionally, two parallel pitch hinge lugs are fixed at the top front end of the upper half of the slewing base, and the tail end of the main bridge body passes through the pitch hinge lugs via a pitch hinge pin, forming a single-axis rotational hinge structure between the main bridge body and the slewing base. A hydraulic cylinder mounting base is fixed to the lower front side of the slewing base. The bottom end of the pitch hydraulic cylinder is hinged to the hydraulic cylinder mounting base through a pin. The top end of the piston rod of the pitch hydraulic cylinder is hinged to the pitch thrust trunnion in the middle section of the bottom of the main bridge body through a pin. The tail end of the telescopic hydraulic cylinder is fixed to the support surface at the tail end inside the main bridge body, and the front end of the piston rod of the telescopic hydraulic cylinder is hinged to the crossbeam inside the tail end of the front telescopic arm.

[0014] A method for operating a small-scale active and passive wave-compensated corridor bridge at sea includes the following steps: Step 1: The hydraulic component loses pressure, retracts and disengages from the support surface on the back of the mechanical pawl, and the mechanical pawl flips and slides outward around the bottom under the downward gravity force transmitted by the counterweight through the concave locking buckle. Step 2: After the mechanical pawl flips outward and slides off, the hook end at the top of the mechanical pawl releases its restraint on the concave lock at the bottom of the hammer, and the hammer completely disengages from the lock and falls down along the vertical guide rail inside the square guide box. Step 3: As the hammer falls downwards, it pulls down the steel cable connected to the top. In the initial stage of the hammer's downward displacement, the steel cable is taut and effectively tensioned to the shorter release rope. Step 4: After the unhooking cable is straightened, the tension generated by the unhooking cable is transmitted to the mechanical forced pin pulling mechanism inside the end pile gripper. The mechanical forced pin pulling mechanism is forced to pull out the mechanical locking mechanism, and the end pile gripper springs open to both sides and releases the mechanical connection. Step 5: After the end pile gripper is released from mechanical connection, the hammer continues to fall downwards along the vertical guide rail, straightening the lifting cable. The lifting cable pulls downwards to the lifting hinge point set in the middle section of the main bridge. Step Six: After the lifting cable pulls the lifting hinge point, the tension drives the main bridge body to rotate upward around the end, and the main bridge body drives the front telescopic arm to lift significantly into the air.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes a square guide rail box, a counterweight, a pressure-holding self-locking release device, and a release cable and hoisting cable with an effective tension length difference. In the event of a complete power outage or hydraulic failure, the pressure-holding self-locking release device releases the counterweight, using the kinetic energy of gravity generated by the free fall of the counterweight as the sole driving force. At this time, by using the geometric length setting of the release cable being shorter than the hoisting cable, the system is forced to generate a timing differential on the time axis. The release cable is preferentially tightened, triggering the mechanical forced pin pulling mechanism to decouple the end-end pile holder. After a brief displacement lag, the hoisting cable is straightened, causing the main bridge body to tilt and lift upwards. This eliminates reliance on external power sources and complex electrical controls, and through anti-interference timing, avoids equipment tearing and falling accidents caused by end-end jamming, achieving safety under extreme conditions.

[0016] Furthermore, the meshing transmission pair consisting of the rotary drive motor, drive gear, and internal gear ring is enclosed in a cylindrical cavity inside the rotary base. This shell isolates the transmission mechanism from the corrosive effects of the high-salt spray environment at sea, reducing the probability of tooth surface rust and abnormal wear. Simultaneously, a vibration-free mounting surface is constructed on the sidewall of the rotary base to support the high-frequency motion reference unit. This isolates the high-frequency localized vibration noise generated by motor operation and mechanical meshing, ensuring that the six-degree-of-freedom dynamic data collected by the integrated gyroscope and other components only reflects the true macroscopic spatial attitude changes of the ship driven by ocean waves, significantly improving the signal-to-noise ratio of the active wave compensation system's data source.

[0017] Furthermore, a high-strength polyurethane buffer pad is fixed to the inner side of the end-end pile gripper opening. Utilizing its high viscoelastic properties, it achieves rheological buffering at the moment of impact when the jaws close, absorbing the rigid impact kinetic energy and significantly increasing the static friction at the contact interface. Simultaneously, the mechanical locking mechanism, in conjunction with the spring potential energy pre-tensioning device, forms a mechanically foolproof locking structure. Once the locking pin is inserted, even if the clamping cylinder unexpectedly depressurizes, the mechanical force of the pre-tensioning spring can still maintain the locked position of the jaws. A pressure relay connected in series in the hydraulic circuit monitors the fluid back pressure in the clamping oil circuit in real time, accurately outputting a level signal representing the completion of the fixing when the clamping force reaches a set threshold.

[0018] Furthermore, by connecting the hydraulic push rod's inlet directly to the main oil supply circuit via the push rod oil pipe, the high pressure of the main oil circuit fluid overcomes the spring force to provide rigid limiting during normal pressure holding. In the event of a severe pressure loss accident such as a pipeline rupture, the pressure head inside the hydraulic push rod drops instantly, and the internal spiral return spring, which has accumulated mechanical energy, releases instantly, pushing back the piston rod and removing support to the back of the mechanical pawl. The mechanical pawl automatically slides outward under the gravitational shear force applied by the concave locking mechanism of the counterweight. No electrical signal or backup power is required, greatly improving the responsiveness and reliability of the energy release triggering.

[0019] Furthermore, considering the different endpoints and force directions of the release cable and the hoisting cable, separate transmission paths were planned for the two high-strength steel wire ropes using guide wheel sets on the side wall of the main bridge and guide grooves on the top. This eliminated the possibility of entanglement, resonance, or sharp scraping against the edges of the external truss that could occur during long-distance dynamic transmission and severe pitching oscillations of the main bridge. It also reduced the risk of localized stress concentration and wire breakage in the steel wire ropes under pulse tension, ensuring that emergency mechanical energy could be smoothly and unimpededly transmitted to the end effector.

[0020] Furthermore, a large-diameter two-position two-way solenoid unloading valve is connected in parallel in the control circuits of the pitch and telescopic hydraulic cylinders. When energized and normally open, the ultra-large flow channel cross-section results in extremely low fluid damping of the hydraulic oil convection between the rod and rodless chambers. This eliminates the rigid hydraulic cushion constraint caused by the blockage of the high-pressure servo main oil circuit, transforming the bridge into a low-load flexible passive follow-up mechanism, significantly reducing system heat generation and energy consumption. The built-in magnetostrictive displacement sensor utilizes the non-contact measurement characteristics of waveguide wires, unaffected by harsh external sea conditions, providing the central controller with high-precision, high-frequency feedback on the cylinder piston rod stroke. This enables the system to possess microsecond-level electronic safety boundary capability for triggering over-limit strong start-up operations just before the passive extension reaches its limit dead point.

[0021] Furthermore, the main bridge structure adopts a spatial tubular truss welded structure with longitudinal main chord members and transverse and diagonal web members. This distribution concentrates the structural material at the edge of the section, greatly improving the flexural modulus and overall torsional stiffness of the bridge section, effectively resisting the alternating bending moment and torque loads caused by the front-end piles and self-weight under large cantilever conditions. The outer wall of the front telescopic arm is fitted with a low-friction coefficient slider embedded in the sliding guide rail, reducing the stick-slip effect in heavy-load linear motion and ensuring that the small hydraulic compensation thrust can be smoothly and without hysteresis converted into displacement response.

[0022] Furthermore, the square guide rail box serves both as mechanical protection and a static balance counterweight for the entire machine. Its own weight-bearing structure and the mass of the suspended counterweight generate a reverse static moment behind the slewing base, effectively counteracting the overturning moment caused by the forward extension of the main bridge body and improving the eccentric loading phenomenon of the slewing bearing. In addition, the sliding guide block on the side of the counterweight tightly engages with the groove of the vertical guide rail, providing motion constraints. This ensures that when the ship encounters wind and waves and experiences roll and pitch, the counterweight is completely restricted to sliding within a unidirectional vertical axis, preventing kinetic energy dissipation and structural damage caused by the horizontal swing of the counterweight impacting the side wall of the box.

[0023] Furthermore, by hinged the bottom ends and piston rod tops of two parallel pitch hydraulic cylinders to the lower part of the slewing base and the middle section of the main bridge bottom, respectively, the pitch drive lever arm is effectively increased. This allows the axial thrust output by the hydraulic cylinders to be efficiently converted into the pitching moment of the bridge. At the same time, the symmetrical arrangement of the two cylinders shares the lateral shear force borne by the main bridge during rotation, avoiding structural torsion caused by unilateral force. The parallel concealed installation of the telescopic hydraulic cylinders shortens the force transmission, making the structure more compact and improving the rigidity of the telescopic action.

[0024] Furthermore, the working method uses depressurization as the trigger source, relying on the potential energy of the weight itself to do work. Utilizing the characteristic of the rope length difference, it preferentially and forcibly decomposes the rigid connection at the end within a short time. After a brief time difference ensuring complete decoupling, the same weight continues to do work to complete the safety-avoidance lifting. This method operates entirely within the scope of pure mechanical transformation, automatically completing the anti-interference evacuation action without any external electronic command interference. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the small active and passive wave compensation corridor bridge at sea according to the present invention. Figure 2 This is a schematic diagram of the timing differential wire rope system of the present invention.

[0026] Among them: 1-slewing base; 2-deck; 3-main bridge body; 4-front telescopic boom; 5-end pile gripper; 6-square guide rail box; 7-counterweight; 8-wire rope; 9-fixed pulley; 10-pitch hydraulic cylinder; 11-helical return spring; 12-top rod oil pipe directly connected to the main oil supply circuit. Detailed Implementation

[0027] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0028] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0029] like Figure 1 As shown, the small active and passive wave compensation corridor bridge of the present invention is constructed on the deck 2 of a small offshore maintenance vessel, and the supporting core of the corridor bridge is the slewing base 1.

[0030] The bottom end face of the slewing base 1 is a flat annular flange, which is rigidly mechanically fixed to the pre-embedded flange of the ship deck 2 by multiple sets of high-strength bolts evenly distributed along the circumference. The interior of the slewing base 1 forms a closed cylindrical cavity. The main slewing tower serves as the main structure of the base, and a slewing drive motor is installed on its bottom plate. The stator housing of the slewing drive motor is fixed to the bottom plate, and its power output shaft extends vertically upward, with a drive gear installed at the end of the output shaft. The upper half of the slewing base 1 is connected to the lower half via a slewing bearing. The inner ring of the slewing bearing is fixed to the lower half of the slewing base 1, and the outer ring is fixed to the upper half of the slewing base 1. An internal gear ring is machined on the inner side of the outer ring, and the drive gear of the slewing drive motor meshes with this internal gear ring. The power input terminal of the slewing drive motor is connected to the output terminal of the ship's power system, and its control signal receiving terminal is connected to the slewing control output terminal of the central controller via a shielded cable. The central controller converts the digital drive commands into analog signals and sends them to the servo driver of the slewing drive motor, driving the upper part of the slewing base 1 to rotate relative to the ship's deck 2 in the horizontal plane. A vibration-free mounting surface is provided on the side wall of the slewing base 1, and a high-frequency motion reference unit is mounted on this vibration-free mounting surface. The high-frequency motion reference unit integrates a multi-axis accelerometer and a gyroscope, and its signal output terminal is connected to the data input terminal of the central controller, sending the real-time acquired six-degree-of-freedom dynamic data of the ship's roll around the X-axis, pitch around the Y-axis, and heave along the Z-axis to the central controller. On the side of the slewing base 1 facing away from the extension direction of the main bridge body 3, a square guide rail box 6 is integrated as a gravity-supported tower. The square guide rail box 6 is a hollow column structure with a rectangular cross-section. The outer layer of the square guide rail box 6 is wrapped with a protective shell to prevent the corrosion of the internal structure by the high salt spray environment at sea. The square guide rail box 6 not only serves as a carrier for the gravitational potential energy recovery device, but its own mass distribution and the weight of the internal structure also serve as a static balance counterweight for the entire slewing mechanism to counteract the static moment generated by the extension of the main bridge body 3 in front and maintain the uniformity of the force on the slewing support.

[0031] The upper half of the slewing base 1 has two parallel pitch hinge lugs at its top front end. The tail end of the main bridge body 3 passes through the pitch hinge lugs via a high-strength pitch hinge pin, achieving a single-axis rotational hinge between the main bridge body 3 and the slewing base 1. This allows the main bridge body 3 to change its pitch angle in the vertical plane around the pitch hinge pin. The main bridge body 3 adopts a rectangular truss structure, welded together from multiple longitudinal main chords and multiple transverse and diagonal web members to provide structural rigidity. The main bridge body 3 has an axially extending sliding guide rail inside. The front telescopic arm 4 is nested inside the main bridge body 3. A low-friction slider is installed on the outer wall of the front telescopic arm 4, which is fitted into the sliding guide rail inside the main bridge body 3, allowing the front telescopic arm 4 to perform linear telescopic movement along the sliding guide rail inside the main bridge body 3. Two pitch hydraulic cylinders 10 are inclinedly installed between the main bridge body 3 and the slewing base 1. The bottom end of each pitch hydraulic cylinder 10 is hinged to the hydraulic cylinder mounting base at the lower front side of the slewing base 1 via a pin, and the top end of its piston rod is hinged to the pitch thrust trunnion at the bottom middle section of the main bridge body 3 via a pin. A single telescopic hydraulic cylinder is installed parallel to the main bridge body 3 between the front telescopic arm 4 and the front telescopic arm 4. The tail end of the telescopic hydraulic cylinder is fixed to the support surface at the tail end inside the main bridge body 3, and the front end of its piston rod is hinged to the crossbeam inside the tail end of the front telescopic arm 4. Magnetostrictive displacement sensors are built into the cylinders of both the pitch hydraulic cylinder 10 and the telescopic hydraulic cylinder. The signal output terminals of each displacement sensor are connected to the status monitoring input terminal of the central controller, which converts the stroke extension data of the hydraulic cylinder piston rod into a standard electrical signal and sends it to the central controller in real time. The control output of the central controller is connected to the signal receiving end of the electromagnetic proportional servo valve of the hydraulic pump station. The high-pressure oil inlet P port of the electromagnetic proportional servo valve is connected to the main oil supply line of the hydraulic pump station, and the return oil port T port is connected to the hydraulic oil tank. Its first working oil port A port and second working oil port B port are connected to the rodless chamber oil inlet and rod chamber oil inlet of the pitch hydraulic cylinder 10 and the telescopic hydraulic cylinder respectively through high-pressure hydraulic rigid pipe and flexible hose. By adjusting the flow rate and direction of the high-pressure hydraulic oil flowing into different chambers of each hydraulic cylinder, the piston rod is driven to generate displacement, thereby driving the main bridge body 3 to complete the pitch angle change and the telescopic compensation action of the front telescopic arm 4.

[0032] The front end of the telescopic boom 4 is rigidly connected to the end-end pile gripper 5 via a flange, which guides the berthing piles of the wind turbine foundation into the center of the jaws during docking. A high-strength polyurethane buffer pad is fixedly installed on the contact surface inside the opening of the end-end pile gripper 5 to absorb the impact kinetic energy during docking and increase contact friction. The end-end pile gripper 5 integrates a clamping mechanism driven by a clamping cylinder, a mechanical locking mechanism, and a mechanical forced pin-pulling mechanism. When the bridge is locked, the locking pin of the mechanical locking mechanism inserts into the locking hole of the clamping mechanism. The mechanical forced pin-pulling mechanism has a spring potential energy pre-tensioning device installed inside, and the locking pin of the mechanical locking mechanism remains locked under the elastic force of the spring potential energy pre-tensioning device. A high-sensitivity pressure relay is installed in the hydraulic circuit of the clamping cylinder of the end-end pile gripper 5, and the signal output terminal of the pressure relay is connected to the feedback input terminal of the central controller. In the hydraulic control circuits of the pitching hydraulic cylinder 10 and the telescopic hydraulic cylinder, in addition to the main high-pressure oil circuit controlled by the electromagnetic proportional servo valve, a large-diameter two-position two-way electromagnetic unloading valve with a response time of less than 30ms is installed in parallel between the rod-side inlet / outlet and rodless-side inlet / outlet ports of each hydraulic cylinder. This large-diameter two-position two-way electromagnetic unloading valve serves as a hydraulic bypass valve; its first interface connects to the rodless-side oil circuit of the hydraulic cylinder, and its second interface connects to the rod-side oil circuit. Its electromagnetic control terminal is connected to the bypass control output terminal of the central controller. The central controller is equipped with low-level control logic for both electrical and hydraulic interlocking. Under this logic, the central controller synchronously sends the zero-position cut-off signal of the electromagnetic proportional servo valve and the energizing opening signal of the large-diameter two-position two-way electromagnetic unloading valve, ensuring that the two actions are completed within the same time period. When the large-diameter two-position two-way solenoid unloading valve is in the normally open energized state, the main high-pressure oil circuit is isolated, and the rod chamber and rodless chamber of the hydraulic cylinder are directly connected through the large-diameter two-position two-way solenoid unloading valve. Because the unloading valve has a sufficiently large diameter and extremely low fluid damping, an internal self-circulation loop with zero pressure difference is formed, so that the hydraulic cylinder loses the rigid constraint of the high-pressure oil, and the piston rod can slide smoothly in the cylinder under the action of external force.

[0033] Inside the square guide rail box 6, a vertical guide rail consisting of two high-strength steel sections is fixedly installed along the vertical direction. A sliding guide block is provided on the side of the suspended cylindrical weight 7, which fits into the groove of the vertical guide rail, restricting the horizontal swing of the weight 7 and allowing it to slide linearly only in the vertical direction. The suspended weight 7 is suspended in the upper half of the square guide rail box 6. The weight 7 is cylindrical, and the downward pulling torque generated by the weight 7 is greater than the combined gravitational downward torque generated by the main bridge body 3, the front telescopic arm 4, and the end pile gripper 5 in the cantilevered state. In the lower half of the vertical guide rail, a pressure-holding self-locking release device is installed. This device consists of a hydraulic component with a push rod oil pipe directly connected to the main oil supply circuit 12 and a mechanical pawl. The bottom of the mechanical pawl is mounted on a fixed base inside the release device via a hinge pin, and its top forms a hook end that engages with the concave lock at the bottom of the suspended cylindrical weight 7. The hydraulic push rod is arranged parallel to the rear side of the mechanical pawl, with the front end of the piston rod abutting against the back support surface of the mechanical pawl. A helical return spring 11 is sleeved inside the rodless chamber of the hydraulic push rod. The oil inlet of the hydraulic push rod is directly connected in parallel to the main control pressure holding circuit of the hydraulic system of the main axle body 3 through a high-pressure hard pipe, and the hydraulic pressure in its chamber is consistent with the pressure of the main system.

[0034] like Figure 2 As shown, a load-bearing ring is located at the center of the top of the counterweight 7. The first end of the time-sequential differential steel wire rope system is fixed to this load-bearing ring. The time-sequential differential steel wire rope system is composed of high-strength, corrosion-resistant steel wire ropes 8. The main steel wire rope 8 extends vertically upward from the top of the suspended cylindrical counterweight 7, passes around multiple sets of fixed pulleys 9 installed on the top of the square guide rail box 6, and then changes its transmission direction to extend towards the main bridge body 3, dividing into two functional branches: a release cable and a lifting cable. The release cable extends towards the front end along the guide wheel set on the side wall of the main bridge body 3, and its end passes through the housing of the end pile gripper 5, connecting with the pull ring of the mechanical forced pin pulling mechanism. The lifting cable extends towards the front end along the guide groove at the top of the main bridge body 3, and its end is anchored to the lifting hinge point set in the middle section of the main bridge body 3. The effective tension length of the release cable is shorter than that of the lifting cable. In standby and normal operation states, neither the release cable nor the lifting cable bears tension. When the gravitational potential energy release mechanism triggers the fall of the hammer 7, the release cable, due to its short effective length, is taut and bears the tension first, while the hoisting cable remains in a relaxed arc state at this moment. Only after the release action is completed and a certain falling displacement has occurred is the hoisting cable taut. This length difference setting constitutes an interference-resistant timing differential transmission mechanism.

[0035] When the small offshore maintenance vessel navigates and approaches the target wind turbine foundation, the operator activates the system at the control console, and the central controller activates the high-precision active docking program. A high-frequency motion reference unit installed on the slewing base 1 collects real-time dynamic displacement and acceleration data of the hull under the action of waves (roll, pitch, heave, sway, pitch, and bow), at a sampling rate exceeding 200 times per second, and continuously sends this data stream to the data input terminal of the central controller. Upon receiving the dynamic data, the central controller establishes a kinematic transformation matrix between the absolute geodetic coordinate system of the wind turbine foundation and the relative coordinate system of the slewing base 1. Based on the inverse kinematic matrix solution algorithm, the central controller calculates in real-time the reverse compensation displacement and velocity required in the relative coordinate system of the main bridge body 3 and the front telescopic arm 4 to remain stationary in the absolute geodetic coordinate system. The central controller converts the calculated displacement compensation into analog control commands and sends these commands to the signal receiver of the electromagnetic proportional servo valve of the hydraulic pump station. The electromagnetic proportional servo valve rapidly adjusts the opening direction and size of its internal valve core according to the voltage or current changes of the high-frequency compensation command, controlling the high-pressure hydraulic oil output from the high-pressure hydraulic pump station to enter and exit the rod-side and rodless-side chambers of two pitch hydraulic cylinders 10 and one telescopic hydraulic cylinder, respectively. By adjusting the fluid volume and system pressure entering each hydraulic chamber at high frequency and precisely, the piston rod of the hydraulic cylinder generates corresponding continuous telescopic displacement, driving the main bridge body 3 to change its pitch angle around the pitch hinge pin, and simultaneously driving the front telescopic arm 4 to change its extension length along the sliding guide rail. During this dynamic compensation process, the end pile gripper 5 of the entire corridor bridge remains relatively stationary and suspended relative to the fixed berthing pile of the wind turbine in the absolute spatial coordinate system. At this time, after the operator confirms that the docking position is accurate, a pile gripping trigger command is sent to the central controller through the control console. After receiving the instruction, the central controller sends an opening signal to the clamping cylinder control valve of the end pile gripper 5. High-pressure oil enters the clamping cylinder, driving the V-shaped jaws of the end pile gripper 5 to close towards the center and tightly lock the mooring pile. The high-strength polyurethane buffer pad inside is in contact with the surface of the mooring pile and is squeezed.

[0036] After the V-shaped jaws of the end-end pile gripper 5 complete the clamping action on the berthing pile, the pressure relay inside the hydraulic circuit of the end-end pile gripper 5 monitors the fluid pressure value of the clamping oil circuit in real time. As the clamping force increases, the oil circuit pressure rises accordingly. When the clamping pressure reaches the set 15MPa, the internal contacts of the pressure relay close, generating a level signal representing the completion of the fixing, and sending this signal to the feedback input terminal of the central controller. After receiving the fixing completion signal, the central controller, under the control of its internal program, performs mode switching within a preset time window of 50ms. The central controller first sends a zero-position command to the control terminal of the electromagnetic proportional servo valve of all control cylinders, causing the servo main valve core to instantly return to the neutral position, cutting off the main servo high-pressure oil supply path connected to the high-pressure pump station. At the same time as cutting off the high-pressure oil path, the central controller sends an energizing command to the solenoid coil of the large-diameter two-position two-way electromagnetic unloading valve connected in parallel between the inlet and outlet ports of the pitch hydraulic cylinder 10 and the telescopic hydraulic cylinder, causing the valve core of all bypass unloading valves to displace and switch to the normally open conducting state. At this point, the main control high-pressure oil circuit is completely blocked, while the rod-side and rodless-side chambers inside the hydraulic cylinder are directly connected to each other through a large-diameter two-position two-way electromagnetic unloading valve. As the ship moves up and down or back and forth and left and right with the waves on the sea surface, the slewing base 1, which is fixed to the hull, undergoes synchronous three-dimensional spatial displacement with the hull. However, the end pile gripper 5 of the pier bridge remains absolutely fixed in its spatial position because it has already tightly clamped the fixed berthing pile. This relative displacement difference between the slewing base 1 and the end pile gripper 5 generates huge mechanical tensile and compressive forces. These forces are transmitted in the opposite direction through the steel structure of the main bridge body 3 and the front telescopic arm 4 and act on the piston rods of the pitching hydraulic cylinder 10 and the telescopic hydraulic cylinder. Since the large-diameter two-position two-way electromagnetic unloading valve is in the fully open state, when the piston moves in the cylinder with the external force, the hydraulic oil discharged from the compressed chamber does not need to overcome the back pressure resistance of the main system, but flows directly into the other chamber with volume expansion through the bypass unloading valve, and the fluid achieves smooth self-circulation between the two chambers. The main bridge body 3 and the front telescopic arm 4 of the covered bridge no longer rely on the rigid support force of the high-pressure hydraulic cylinders. Instead, they are transformed into a flexible floating linkage mechanism with one end hinged to the base and the other end fixed to the mooring pile. The bridge body moves freely in extension, retraction, and pitching motion with the waves of the ship. During this relatively long period of personnel passage, the hydraulic pump station does not need to continuously output high-pressure hydraulic power, and the covered bridge enters a low-load follow-up phase, reducing overall energy consumption and component heat generation.

[0037] Throughout the entire operational cycle of the jet bridge during fluid unloading and zero-energy flexible servoing, the safety monitoring mechanism remains continuously operational. Magnetostrictive displacement sensors, built into the pitch and telescopic hydraulic cylinders (10 and 10 respectively), serve as an electronic safety boundary system. They continuously collect real-time data on the actual stroke position of the piston rod within the cylinder and send this data to the central controller's status monitoring terminal. The central controller's logic judgment module cyclically reads this real-time stroke data and dynamically compares it with the preset displacement limit safety threshold in the system memory. When a sudden giant wave causes excessive displacement of the ship, resulting in extreme stretching or compression of the relative distance between the slewing base 1 and the end-mounted pile driver 5, causing the piston rod stroke of either of the two pitch cylinders (10) or one telescopic cylinder to reach 90% of its total physical stroke, the central controller determines that the current ship position poses a serious risk of breaking the jet bridge's mechanical structure or impacting the cylinder to its mechanical dead point. The central controller's over-limit forced start procedure is triggered, generating an emergency control sequence within a millisecond-level time window. The central controller first cuts off the energizing signal to the large-diameter two-position two-way solenoid unloading valve. The unloading valve instantly resets and closes under the action of its internal spring, blocking the fluid self-circulation loop between the rod-side and rodless-side chambers of the hydraulic cylinder. Simultaneously, the central controller sends a high-frequency actuation signal to the solenoid proportional servo valve, reopening the servo high-pressure oil circuit from the high-pressure pump station to the hydraulic cylinder. High-pressure hydraulic oil instantly fills the corresponding working chamber of the hydraulic cylinder, restoring the system's rigid support and active driving force to the pitching hydraulic cylinder 10 and the telescopic hydraulic cylinder. The central controller forcibly takes over the attitude control of the entire bridge, driving the hydraulic cylinder piston rod to retract or extend within the safe stroke range to perform attitude correction actions to counteract the ultimate tensile force. Alternatively, if assessment indicates that correction is impossible, it automatically drives the pressure relief circuit of the end pile gripper 5 to forcibly open, performing an emergency detachment and evacuation of the bridge from the wind turbine foundation, ensuring the survival of personnel and equipment.

[0038] When a marine maintenance vessel experiences a catastrophic failure such as a complete power outage of its generator sets, or an extreme condition such as a rupture in the main control hydraulic pipeline leading to a large fluid leak, the bridge loses its power source. The fluid pressure in the main control pressure-holding circuit of the main bridge body 3 hydraulic system, no longer maintained by the hydraulic pump, begins to rapidly drop towards zero. Because the hydraulic push rod in the pressure-holding self-locking release device located inside the square guide rail box 6 has its oil inlet directly connected in parallel to the main control pressure-holding circuit via a rigid pipe, the fluid pressure inside the rodless chamber of the hydraulic push rod drops sharply in sync with the main oil circuit. When the pressure in the pipeline system falls below the set safety threshold of three MPa, the positive thrust generated by the fluid pressure in the rodless chamber of the hydraulic push rod acting on the piston can no longer overcome the reverse mechanical rebound force generated by the helical return spring 11 sleeved inside the push rod. The helical return spring 11 quickly extends, pushing the piston rod of the hydraulic push rod backward into the cylinder. The retraction of the piston rod causes its front end to disengage from the force-bearing support surface on the back of the mechanical pawl. After losing its rear rigid limiting support, the mechanical pawl, under the downward gravitational force transmitted through the latch by the suspended cylindrical weight 7, rotates and slides outward around its bottom hinge pin, thus releasing the locking constraint of the top hook end on the bottom latch of the suspended cylindrical weight 7. The suspended cylindrical weight 7 completely disengages from the pressure-holding self-locking release device and, under its own weight, its side sliding guide block accelerates downward along the vertical guide rail inside the square guide box 6, rapidly converting its enormous gravitational potential energy into downward kinetic energy. During its descent, the suspended cylindrical weight 7 pulls the timing differential steel wire rope system connected to its top hanging ring. The steel wire rope group 8 passes around the top fixed pulley 9 to transmit the tension. Because the effective tension length of the release cable is shorter than that of the hoisting cable during the design and assembly process, the release cable, which exhibits a relaxed arc, is straightened first and becomes taut during the initial stage of the downward displacement of the suspended cylindrical weight 7. The instantaneous mechanical tension transmitted inside the release cable acts directly on the pull ring of the mechanical forced pin pulling mechanism inside the end pile holder 5. This tension overcomes the preload set by the spring potential energy preload device, pulling the locking pin of the mechanical locking mechanism out of the lock hole. After the locking pin is pulled out, the V-shaped jaws of the end pile holder 5 quickly spring open to both sides under the action of the internal preload spring, releasing the mechanical connection between the front end of the corridor bridge and the wind turbine mooring pile. During the time lag period of 0.1 to 0.3 seconds after the release action is completed, as the suspended cylindrical weight 7 continues to fall downward along the vertical guide rail and accumulates displacement, the longer hoisting cable is straightened and becomes taut. At this moment, the entire ship lost power, causing the large-diameter two-position two-way electromagnetic unloading valve to be in the de-energized and normally closed state. However, at the same time, the electromagnetic proportional servo valve was also in the neutral position depressurized state due to the power outage. The oil inside the two chambers of the pitch hydraulic cylinder 10 lost its high-pressure sealing constraint and was in a depressurized and undamped state. The continuous tension transmitted inside the hoisting cable acted on the hoisting hinge point in the middle section of the main bridge body 3.Because the downward pulling moment generated by the suspended cylindrical counterweight 7 is greater than the downward sag moment of the bridge structure itself, the lifting cable pulls the main bridge body 3 against its own weight, causing it to rotate upwards around the pitch hinge pin at the top front of the slewing base 1. The main bridge body 3, along with the internal front telescopic arm 4, is pulled significantly upwards by the lifting cable until it reaches the designed maximum elevation angle safe position. The slewing base 1 remains on the deck 2, while the main bridge body 3 is completely separated from the wind turbine foundation structure. Relying on the mechanical transmission between purely solid components, it completes the automatic decoupling and overturning self-rescue process in a state of 100% power supply and no hydraulic power.

[0039] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0040] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0041] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0042] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0043] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

[0044] It should be understood that the above description is for illustrative purposes and not for limitation. Many embodiments and applications beyond the provided examples will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this application should not be determined by reference to the above description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

Claims

1. A small-scale active and passive wave-compensating corridor bridge for marine applications, characterized in that, It includes a slewing base (1), a main bridge body (3) and a front telescopic boom (4); The upper half of the slewing base (1) is hinged to the top of the main bridge body (3), and a sliding guide rail is fixed inside the main bridge body (3). The front telescopic arm (4) is fitted and connected to the sliding guide rail. A pitching hydraulic cylinder (10) is hinged between the main bridge body (3) and the slewing base (1). A telescopic hydraulic cylinder is installed in parallel between the main bridge body (3) and the front telescopic arm (4). The front end of the front telescopic arm (4) is connected to the end pile gripper (5), and a mechanical locking mechanism and a mechanical forced pin pulling mechanism are installed inside the end pile gripper (5). A square guide rail box (6) is fixed on one side of the rotating base (1). A vertical guide rail is fixed inside the square guide rail box (6) along the vertical direction. A counterweight (7) is slidably connected on the vertical guide rail. A pressure-holding self-locking release device is installed in the lower half area of ​​the vertical guide rail. The pressure-holding self-locking release device includes a hydraulic component and a mechanical pawl. The top of the mechanical pawl is formed as a hook end. A concave lock is provided at the bottom of the counterweight (7) to engage with the hook end. A steel wire rope (8) is connected to the top center of the counterweight (7). A fixed pulley (9) is installed on the top of the square guide box (6). The steel wire rope (8) passes around the fixed pulley (9) and extends towards the main bridge body (3) and is divided into a release cable and a lifting cable. The end of the release cable passes through the housing of the end pile holder (5) and is connected to the mechanical forced pin pulling mechanism. A lifting hinge point is fixed in the middle section of the main bridge body (3). The end of the lifting cable is connected to the lifting hinge point. The effective tension length of the release cable is shorter than the effective tension length of the lifting cable.

2. The small-scale active and passive wave-compensating corridor bridge at sea according to claim 1, characterized in that, The rotating base (1) is designed as a closed cylindrical cavity. A rotary drive motor is fixed on the bottom plate of the cylindrical cavity. The rotary drive motor has an output shaft that extends vertically upward, and a drive gear is connected to the end of the output shaft. The upper half of the slewing base (1) is connected to the lower half through a slewing bearing. The inner ring of the slewing bearing is fixed to the lower half of the slewing base (1), and the outer ring of the slewing bearing is fixed to the upper half of the slewing base (1). An internal gear ring is machined on the inner side of the outer ring of the slewing bearing, and the drive gear meshes with the internal gear ring. The side wall of the rotating base (1) is machined with a vibration-free mounting base surface, and a high-frequency motion reference unit is fixed on the vibration-free mounting base surface.

3. The small-scale active and passive wave-compensating corridor bridge at sea according to claim 1, characterized in that, The end-end pile gripper (5) is equipped with a clamping mechanism and a clamping cylinder. The output end of the clamping cylinder is connected to the clamping mechanism. The mechanical locking mechanism includes a locking pin. The locking pin is inserted into the locking hole of the clamping mechanism in the locked state. The mechanical forced pin pulling mechanism is equipped with a spring potential energy preload device, which abuts against the outside of the locking pin. A high-strength polyurethane buffer pad is fixed on the contact surface inside the opening of the end pile gripper (5); a pressure relay is connected in series in the hydraulic circuit of the clamping cylinder.

4. The small-scale active and passive wave-compensating corridor bridge at sea according to claim 1, characterized in that, The pressure-holding self-locking release device has a fixed base inside, and the bottom of the mechanical pawl is mounted on the fixed base through a hinge pin. The hydraulic assembly includes a hydraulic push rod arranged in parallel to the rear side of the mechanical pawl, the hydraulic push rod having a piston rod, the front end of the piston rod abutting against the force-bearing support surface on the back side of the mechanical pawl; The hydraulic push rod has a rodless cavity inside, and a helical return spring (11) is sleeved inside the rodless cavity. The oil inlet of the hydraulic push rod is connected to the push rod oil pipe, which is directly connected to the main oil supply circuit (12).

5. The small-scale active and passive wave-compensating corridor bridge at sea according to claim 1, characterized in that, The main bridge body (3) has a guide wheel assembly fixed on its side wall, and the unhooking cable extends along the guide wheel assembly to the front end of the outer shell of the end pile gripper (5); A guide groove is provided on the top of the main bridge body (3), and the lifting cable extends along the guide groove to the lifting hinge point of the main bridge body (3).

6. The small-scale active and passive wave-compensating corridor bridge at sea according to claim 1, characterized in that, Both the pitch hydraulic cylinder (10) and the telescopic hydraulic cylinder include a rod chamber and a rodless chamber. A large-diameter two-position two-way electromagnetic unloading valve is connected in parallel between the oil inlet and outlet ports of the rod chamber and the oil inlet and outlet ports of the rodless chamber of the pitch hydraulic cylinder (10) and the telescopic hydraulic cylinder. The first port of the large-diameter two-position two-way electromagnetic unloading valve is connected to the oil circuit of the rodless chamber, and the second port is connected to the oil circuit of the rod chamber. Both the pitch hydraulic cylinder (10) and the telescopic hydraulic cylinder have built-in magnetostrictive displacement sensors inside their cylinder barrels.

7. The small-scale active and passive wave-compensating corridor bridge for marine use according to claim 1, characterized in that, The main bridge body (3) is a rectangular truss structure, which is welded together by multiple longitudinal main chords and multiple transverse and diagonal web members; A slider with a low coefficient of friction is fixed on the outer wall of the front telescopic arm (4), and the slider is fitted inside the sliding guide rail.

8. The small-scale active and passive wave-compensating corridor bridge at sea according to claim 1, characterized in that, The square guide rail box (6) is a hollow column structure with a rectangular cross section, and the outer layer of the square guide rail box (6) is covered with a protective shell; The weight (7) is cylindrical in shape. A sliding guide block is fixed on the side of the weight (7). A groove is opened in the vertical guide rail, and the sliding guide block is fitted into the groove. The weight (7) is suspended in the upper part of the square guide rail box (6).

9. The small-scale active and passive wave-compensating corridor bridge for marine use according to claim 1, characterized in that, Two parallel pitch hinge lugs are fixed at the top front end of the upper half of the slewing base (1). The tail end of the main bridge body (3) passes through the pitch hinge lugs via the pitch hinge pin, forming a single-axis rotation hinge structure between the main bridge body (3) and the slewing base (1). A hydraulic cylinder mounting base is fixed on the lower front side of the slewing base (1). The bottom end of the pitch hydraulic cylinder (10) is hinged to the hydraulic cylinder mounting base through a pin. The top end of the piston rod of the pitch hydraulic cylinder (10) is hinged to the pitch thrust trunnion at the bottom middle section of the main bridge body (3) through a pin. The cylinder tail end of the telescopic hydraulic cylinder is fixed to the support surface at the tail end inside the main bridge body (3), and the piston rod front end of the telescopic hydraulic cylinder is hinged to the crossbeam inside the tail end of the front telescopic arm (4).

10. A working method for a small-scale active and passive wave-compensating corridor bridge at sea based on any one of claims 1-9, characterized in that, Includes the following steps: Step 1: The hydraulic component loses pressure, the hydraulic component retracts and disengages from the force support surface on the back of the mechanical pawl, and the mechanical pawl flips and slides outward around the bottom under the action of the downward gravity component transmitted by the weight (7) through the concave lock. Step 2: After the mechanical pawl flips outward and slides off, the hook end at the top of the mechanical pawl releases the limit on the concave lock at the bottom of the hammer (7), and the hammer (7) is completely released from the lock and falls down along the vertical guide rail inside the square guide rail box (6). Step 3: During the downward fall of the hammer (7), the steel wire rope (8) connected to the top is pulled downward. In the initial stage of the downward displacement of the hammer (7), the steel wire rope (8) is stretched to effectively tighten the short-length release rope. Step 4: After the unhooking cable is straightened, the tension generated by the unhooking cable is transmitted to the mechanical forced pin pulling mechanism inside the end pile holder (5). The mechanical forced pin pulling mechanism is forced to pull out the mechanical locking mechanism, and the end pile holder (5) springs open to both sides and releases the mechanical connection. Step 5: After the end pile gripper (5) is released from mechanical connection, the hammer (7) continues to fall down along the vertical guide rail to straighten the lifting cable. The lifting cable pulls down the lifting hinge point set in the middle section of the main bridge body (3). Step 6: After the lifting cable pulls the lifting hinge point, the tension drives the main bridge body (3) to rotate upward around the end, and the main bridge body (3) drives the front telescopic arm (4) to rise significantly into the air.

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