A self-climbing double-rocker-arm pole-holding rod stress structure anti-overturning mechanism

Abstract

The present application relates to the technical field of pole stabilizing, in particular to a self-climbing double-joint pole stabilizing mechanism, comprising a cylinder body fixedly arranged in the interior of a rotating joint, a first chamber and a second chamber with different effective cross-sectional areas and being separated from each other being arranged in the interior of the cylinder body, a double-end piston rod slidably arranged in the cylinder body, two ends of the double-end piston rod being sealingly fitted in the first chamber and the second chamber respectively, the first chamber being divided into a first left chamber and a first right chamber, and the second chamber being divided into a second left chamber and a second right chamber, a hydraulic interconnection pipeline system, each chamber of the first chamber and the second chamber being cross-connected with a rod cavity and a rodless cavity of a corresponding side of a variable-amplitude hydraulic cylinder, so that the hydraulic pressure generated by the load difference of the two sides of the joint can be transmitted to each other through the double-end piston rod, and an automatically generated reverse balance torque is generated, and a proportional adjusting valve, which is connected in series in the hydraulic interconnection pipeline system and is provided with a slidable spool.

Description

Technical Field

[0001] This invention relates to the field of pole stabilization technology, specifically to an anti-tipping mechanism for a self-climbing double-rocker pole force-bearing structure. Background Technology

[0002] Self-climbing double-arm gantry cranes are key equipment in the erection of transmission line towers. Their working principle is as follows: two symmetrically arranged arms are positioned on either side of the slewing joint. Each arm is driven by a variable-amplitude hydraulic cylinder to change its pitch angle, thereby achieving variable-amplitude lifting and positioning operations. In actual hoisting, the loads suspended by the two arms are often asymmetrical; for example, one side may be hoisting tower materials while the other is unloaded or has counterweights. In this case, the overturning moments generated by the two arms on the slewing joint are unequal. If not balanced in time, this will cause the slewing joint and even the entire gantry crane tower to bear excessive eccentric bending moments, which may lead to structural instability or even overturning accidents in severe cases.

[0003] Existing anti-rollover solutions can be mainly divided into the following categories: Firstly, as described in patent document CN214399591U, a pole-lifting balance arm and a pole are proposed. The pole-lifting balance arm includes a balance arm body and a counterweight platform. The balance arm body includes a track and guardrails. The track is set along the length of the balance arm body, and guardrails are set on both sides of the track. The counterweight platform is set on the track and can move along the track. The counterweight platform is equipped with a counterweight. By setting the counterweight platform and the track, the counterweight platform can move along the track. The pole-lifting balance arm can change the torque generated by the pole-lifting balance arm by adjusting the position of the counterweight platform. The guardrails can play a protective role, making it difficult for the counterweight platform to fall when the pole rotates.

[0004] Its drawbacks are: the counterweight adjustment requires manual intervention, the response speed is slow, and it cannot keep up with load changes in real time; moreover, the counterweight itself increases the overall weight of the equipment and transportation costs.

[0005] Secondly, as disclosed in patent document CN222665224U, a double-rocker arm lifting pole includes a rocker arm mechanism, a lifting pole mechanism, and a hook mechanism. The rocker arm mechanism has a lifting pole mechanism on one side, and a hook mechanism at the bottom. The rocker arm mechanism includes a rocker arm fixing component. This invention, by setting up a rocker arm mechanism, starts a motor, which drives a cable shaft to rotate via a coupling. The cable shaft drives a first cable reel to rotate. When the first cable reel rotates and begins to tighten, simultaneously, a hydraulic cylinder push rod pushes towards the lifting pole. The first cable, through a second cable fixing component and a hydraulic cylinder, lifts the rocker arm. This combination of motor drive and hydraulic cylinder push achieves smooth and stable rocker arm lifting, avoiding safety hazards caused by improper manual operation or mechanical failure.

[0006] Its drawbacks are: the system contains a large number of electronic components, and its reliability is difficult to guarantee in the high temperature, high humidity, strong vibration and dusty environment of field construction; the zero drift and electromagnetic interference of electronic sensors are prominent problems; and the system has high cost and high maintenance technical requirements, which is not conducive to its promotion in field scenarios such as power construction.

[0007] Therefore, this application proposes an anti-tipping mechanism for a self-climbing double rocker arm pole-supported force-bearing structure. Summary of the Invention

[0008] The purpose of this invention is to provide an anti-tipping mechanism for a self-climbing double rocker arm pole-supported structure, so as to solve the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: an anti-tipping mechanism for a self-climbing double rocker arm support structure, comprising a swivel joint, on both sides of which rocker arms are rotatably connected, and two luffing hydraulic cylinders, one end of each luffing hydraulic cylinder being rotatably connected to the top of the swivel joint, and the other end being rotatably connected to the corresponding rocker arm through a rocker arm hinge lug fixedly connected to the top of the rocker arm, and further comprising: The cylinder body is fixedly installed inside the rotating joint, and its interior has a first chamber and a second chamber with different effective cross-sectional areas that are separated from each other. A double-ended piston rod is slidably disposed in the cylinder body, with its two ends of pistons respectively sealingly fitted into the first chamber and the second chamber, dividing the first chamber into a first left chamber and a first right chamber, and dividing the second chamber into a second left chamber and a second right chamber; The hydraulic interconnected pipeline system cross-connects each chamber of the first and second chambers with the rod-side and rodless chambers of the corresponding side of the luffing hydraulic cylinder, so that the hydraulic pressure generated by the load difference between the two rocker arms can be transmitted to each other through the double-ended piston rod, automatically generating a reverse balancing torque. A proportional regulating valve is connected in series in the hydraulic interconnection pipeline system. It has a sliding valve core inside, and the valve core has a throttling structure for changing the effective flow area of ​​the flow channel.

[0010] Preferably, the hydraulic interconnection pipeline system includes: a rod-side connecting pipe for the left hydraulic cylinder, one end of which is connected to the first left cavity and the other end of which is connected to the rod-side cavity of the left luffing hydraulic cylinder; a rodless-side connecting pipe for the right hydraulic cylinder, one end of which is connected to the first right cavity and the other end of which is connected to the rodless-side cavity of the right luffing hydraulic cylinder; a rodless-side connecting pipe for the left hydraulic cylinder, one end of which is connected to the second left cavity and the other end of which is connected to the rodless-side cavity of the left luffing hydraulic cylinder; and a rod-side connecting pipe for the right hydraulic cylinder, one end of which is connected to the second right cavity and the other end of which is connected to the rod-side cavity of the right luffing hydraulic cylinder.

[0011] Preferably, the proportional regulating valve includes a proportional regulating valve body, fixedly installed below or to the side of the cylinder body, with a first symmetrical fluid hole and a second symmetrical fluid hole spaced apart along the axial direction inside. Each of the first and second symmetrical fluid holes has an inlet and an outlet distributed along the axial direction. Two large-diameter cavity series pipes are connected in series, one end of which is connected to the inlet of the second symmetrical fluid hole and the other end to the first left cavity; the other end of which is connected to the outlet of the second symmetrical fluid hole and the other end to the first right cavity, thereby connecting the proportional regulating valve in series to a hydraulic passage formed by the rod-side connecting pipe of the left hydraulic cylinder, the first cavity, and the rodless connecting pipe of the right hydraulic cylinder; and two small-diameter cavity series pipes are connected in series, one end of which is connected to the outlet of the first symmetrical fluid hole. One end of the valve is connected to the inlet, and the other end is connected to the second left cavity. One end of the other small-diameter cavity series pipe is connected to the outlet of the first symmetrical fluid orifice, and the other end is connected to the second right cavity, thereby connecting the proportional regulating valve in series into the hydraulic passage formed by the rodless cavity connecting pipe of the left hydraulic cylinder, the second cavity, and the rod cavity connecting pipe of the right hydraulic cylinder. The spool valve core is cylindrical and slidably fitted into the center hole of the proportional regulating valve body along the axial direction. A first throttling ring groove corresponding to the first symmetrical fluid orifice and a second throttling ring groove corresponding to the second symmetrical fluid orifice are opened on its outer circumference. The axial width of the first throttling ring groove and the orifice width of the first symmetrical fluid orifice are matched to form a first variable throttling orifice, and the axial width of the second throttling ring groove and the orifice width of the second symmetrical fluid orifice are matched to form a second variable throttling orifice.

[0012] Preferably, a bracket is fixedly connected to the top of the cylinder body, and a connecting slider is provided at the top of the bracket. The connecting slider serves as a fulcrum to support the center position of a lever, allowing the lever to swing in a vertical plane with the connecting slider as the rotation center. A longitudinal groove is formed at the center position of the lever along its width direction, and the connecting slider is accommodated in the longitudinal groove. The connecting slider is elastically connected to the inner wall of the longitudinal groove through a misaligned spring plate. The height of the longitudinal groove is greater than the height of the connecting slider, thereby allowing the lever to float relative to the connecting slider along the extension direction of the longitudinal groove. An output transmission rod is fixed to the top of the lever, and the lower end of the output transmission rod is connected to the valve core. When the lever swings around the connecting slider, the angular displacement of the lever is converted into the axial linear displacement of the valve core through the output transmission rod.

[0013] Preferably, the lower end of the spool valve core is integrally or fixedly connected to a valve core connecting rod, which extends downward through the bottom of the proportional regulating valve body and slides in a sealing fit with it; the lower end of the output transmission rod is movably connected to the top surface of the lever through a first ball cage joint, and the upper end of the output transmission rod is movably connected to the lower end of the valve core connecting rod through a second ball cage joint, so that the swing motion of the lever can be transmitted to the valve core connecting rod without jamming through the output transmission rod, and drive the spool valve core to move axially synchronously; a return spring is sleeved on the outer section of the valve core connecting rod that extends out of the proportional regulating valve body, the upper end of the return spring abuts against the bottom surface of the proportional regulating valve body, and the lower end abuts against a stop on the valve core connecting rod.

[0014] Preferably, it further includes a displacement detection and transmission mechanism for mechanically transmitting the angular displacement of the two rocker arms to both ends of the lever. This mechanism includes: two angle-sensing links, one end of each link being rotatably connected to the corresponding rocker arm hinge plate, with the rotatable connection point located on the same axis as the piston end of the variable-amplitude hydraulic cylinder and the rotatable connection point of the rocker arm hinge plate; the other end of each angle-sensing link being rotatably connected to the side of the cylinder body; and a fixed connection at the end of each angle-sensing link near the cylinder body. There is an angular conversion gear, and an eccentric pin is provided on the end face of the angular conversion gear. The left and right ends of the lever are respectively connected to a flexible push-pull cable through a ball cage joint. Each flexible push-pull cable has an elongated groove or a fork inside. The eccentric pin on the angular conversion gear on the same side extends into and engages with the elongated groove or fork, so that the rotational motion of the angular conversion gear is converted into the linear displacement of the flexible push-pull cable along its own axis through the engagement of the eccentric pin and the elongated groove or fork, thereby pushing or pulling the corresponding end of the lever.

[0015] Preferably, the lever is configured as an equal-arm or unequal-arm lever with the connecting slider as the fulcrum. Its left end receives linear displacement input from the left flexible push-pull cable, and its right end receives linear displacement input from the right flexible push-pull cable. When the linear displacements input on both sides are equal in magnitude and symmetrical in direction, the net rotation of the lever around the connecting slider is zero, the output transmission rod does not produce displacement, and the spool valve core remains in the middle position. When the linear displacements input on both sides are unequal in magnitude, the lever produces a net rotation proportional to the displacement difference, causing the output transmission rod to produce a corresponding axial displacement, driving the spool valve core to deviate from the middle position, causing the effective flow area ratio of the first variable throttle orifice and the second variable throttle orifice to change accordingly to the displacement difference, thereby adaptively adjusting the hydraulic flow resistance ratio flowing through the first symmetrical fluid orifice and the second symmetrical fluid orifice, and realizing adaptive matching of the hydraulic pressure transmission ratio with the angle difference of the two rocker arms.

[0016] Preferably, the outer circumferential surfaces of the two pistons of the double-ended piston rod are provided with micro-inverted cone structures and / or pressure equalizing grooves. The micro-inverted cone structure causes the piston diameter to gradually decrease from the high-pressure side to the low-pressure side, and the pressure equalizing grooves extend along the circumference of the piston. The two work together to eliminate the hydraulic clamping force caused by machining errors or off-center loads, allowing the double-ended piston rod to float freely within a micrometer range under the four-chamber pressure difference between the first and second chambers. This automatically compensates for the displacement difference generated by the rocker arms of the two variable-amplitude hydraulic cylinders when they are at different angles, maintains the continuity and pressure balance of the hydraulic interconnection circuit, and avoids cavitation or oil trapping in the system.

[0017] Preferably, the angle sensing link has a telescopic rod inside that can extend and retract along its axial direction.

[0018] Preferably, each flexible push-pull cable is fitted with a guide sleeve fixed to the cylinder or bracket, and the guide sleeve restricts the flexible push-pull cable to slide linearly along its axial direction only.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1. Fully mechanical hydraulic architecture, without electronic components. The entire signal detection, signal processing, and signal execution chain of this invention is completed by the cooperation of purely mechanical and hydraulic components such as angle sensing linkage, angle position conversion gear, flexible push-pull cable, lever, output transmission rod, spool valve, double-ended piston rod, and hydraulic interconnection pipeline. It does not contain any electronic sensors, electronic controllers, or electro-hydraulic servo components, fundamentally avoiding the reliability problems of electronic systems in harsh field construction environments, and has extremely strong environmental adaptability and long-term maintenance-free capability.

[0020] 2. Adaptive Full-Condition Balancing. This invention uses a lever to perform a purely mechanical subtraction operation on the angular displacement of the two rocker arms, outputting a signal proportional to the displacement difference to drive a proportional control valve to change the effective flow area ratio of the flow channel, thereby adjusting the hydraulic pressure transmission ratio to follow the changes in the lever arm ratio of the two rocker arms in real time. Compared with a purely continuous scheme with a fixed area ratio, this achieves near-optimal balancing across the entire operating range of the rocker arms, from the minimum to the maximum elevation angle.

[0021] 3. Micro-amplitude floating self-compensating displacement difference. This invention utilizes the micron-level axial floating generated by the pressure difference between the first and second chambers of the double-ended piston rod to automatically compensate for the displacement difference caused by the different rocker arm angles of the two variable-amplitude hydraulic cylinders. It can maintain the continuity and pressure stability of the hydraulic interconnection circuit without the need for additional oil replenishment circuits or accumulators, effectively avoiding cavitation and oil trapping phenomena.

[0022] 4. Elimination of hydraulic clamping force. The micro-conical structure and pressure equalizing groove on the outer surface of the double-ended piston rod can effectively eliminate the hydraulic clamping force caused by machining errors or off-center loads, allowing the piston rod to respond flexibly even under extremely small pressure differentials, ensuring the sensitivity and reliability of the micro-amplitude floating compensation function. Attached Figure Description

[0023] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is a schematic diagram of the structure of the rotary joint in this invention; Figure 3 This is an exploded view of the cylinder body, proportional regulating valve body, and variable amplitude hydraulic cylinder in this invention; Figure 4 This is a schematic diagram of the cylinder and lever structure in this invention; Figure 5 This is a schematic diagram showing the connection between the cylinder body and the variable amplitude hydraulic cylinder in this invention; Figure 6 This is a schematic diagram of the cylinder block in this invention; Figure 7 For the present invention Figure 6 Enlarged structural diagram at point A; Figure 8 This is a schematic diagram of the structure of the large-diameter cavity series tube and the small-diameter cavity series tube in this invention; Figure 9 This is a schematic diagram of the large-diameter cavity and the small-diameter cavity in this invention; Figure 10 This is a schematic diagram of the slide valve core in this invention; Figure 11 This is a schematic diagram of the structure of the first and second throttling ring grooves in this invention.

[0024] In the diagram: 100, swivel joint; 101, standard section; 102, rocker arm; 103, luffing hydraulic cylinder; 104, rocker arm hinge plate; 200, cylinder body; 201, large-diameter chamber; 202, small-diameter chamber; 203, double-ended piston rod; 204, connecting pipe for the rod chamber of the left hydraulic cylinder; 205, connecting pipe for the rodless chamber of the right hydraulic cylinder; 206, connecting pipe for the rodless chamber of the left hydraulic cylinder; 207, connecting pipe for the rod chamber of the right hydraulic cylinder; 300, proportional regulating valve body; 301, connecting pipe for the large-diameter chamber; 302, connecting pipe for the small-diameter chamber. 303. Connecting pipe; 304. Slide valve core; 305. Valve core connecting rod; 306. Return spring; 307. First symmetrical fluid orifice; 308. Second symmetrical fluid orifice; 309. First throttling ring groove; 400. Lever; 401. Angle sensing connecting rod; 402. Telescopic rod; 403. Angle position conversion gear; 404. Flexible push-pull cable; 405. Bracket; 406. Longitudinal slide groove; 407. Connecting slider; 408. Misaligned spring plate; 409. Output transmission rod. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1: Please refer to Figure 1 - Figure 11 The present invention provides a technical solution: an anti-overturning mechanism for a self-climbing double rocker arm gantry structure. The mechanism is installed inside and around the rotating section 100 of the self-climbing double rocker arm gantry and is used to automatically generate a reverse balancing torque when the two rocker arms 102 are subjected to asymmetrical loads, so as to prevent the rotating section 100 and the tower body from overturning due to eccentric bending moment.

[0027] The mechanism includes a slewing section 100, which contains a standard section 101 for connection with adjacent boom sections. A rocker arm 102 is rotatably connected to each side of the slewing section 100 via a horizontal hinge axis. The two rocker arms 102 are symmetrically arranged and can pitch and swing (i.e., luffing) in a vertical plane around their respective hinge axes. Two luffing hydraulic cylinders 103 are respectively positioned corresponding to the left and right rocker arms 102. The cylinder body end (i.e., the bottom end) of each luffing hydraulic cylinder 103 is rotatably connected to the top of the slewing section 100, and its piston rod end (i.e., the telescopic end) is rotatably connected to the corresponding rocker arm 102 via a rocker arm hinge lug 104. The rocker arm hinge lug 104 is fixed to the top of the rocker arm 102 by welding or bolting. When the luffing hydraulic cylinder 103 extends or retracts, it drives the rocker arm 102 to pitch and swing around its horizontal hinge axis, changing the elevation angle of the rocker arm 102.

[0028] The mechanism includes a cylinder body 200, which is fixed to the center of the rotating joint 100 by welding or bolting. Inside the cylinder body 200, along the same axial direction (preferably vertical, but also horizontal or inclined, depending on the internal spatial layout of the rotating joint), there are mutually separated first and second chambers. In this embodiment, the first chamber is a large-diameter chamber 201, whose effective cross-sectional area (i.e., effective piston area) of the piston mating hole is A1; the second chamber is a small-diameter chamber 202, whose effective cross-sectional area of ​​the piston mating hole is A2, and A1 > A2. The two chambers are arranged along the same axis and separated by an intermediate partition wall, which has a sealing through-hole for the double-ended piston rod 203 to pass through.

[0029] The double-ended piston rod 203 is a slender rod, either integral or segmented. Its upper end is fixed with a first piston that slides and seals against the inner wall of the first chamber (large-diameter chamber 201), and its lower end is fixed with a second piston that slides and seals against the inner wall of the second chamber (small-diameter chamber 202). Thus, the first chamber (large-diameter chamber 201) is divided by the first piston into an upper first left chamber and a lower first right chamber; the second chamber (small-diameter chamber 202) is divided by the second piston into an upper second left chamber and a lower second right chamber. The double-ended piston rod 203, as a whole, can slide freely along the common axis of the two chambers.

[0030] The ratio of the effective cross-sectional areas of the first chamber to the second chamber (A1 / A2) is designed and selected based on the ratio of the effective area of ​​the rod chamber to the effective area of ​​the rodless chamber of the luffing hydraulic cylinder 103. The design principle is to ensure that the fixed area ratio of the double-ended piston rod 203 can cover the lever arm ratio requirements of both luffing hydraulic cylinders at different rocker arm angles throughout the entire operating range through slight adjustments by the proportional control valve (see below), thereby achieving global optimization of the hydraulic pressure transmission ratio. In a preferred embodiment, the ratio of A1 / A2 ranges from 1.2:1 to 3:1, with the specific value determined based on the cylinder diameter and rod diameter parameters of the luffing hydraulic cylinder.

[0031] The mechanism also includes a hydraulic interconnection piping system. This system consists of four independent hydraulic lines that cross-connect the four chambers of the first and second chambers with the rod-side and rodless chambers of the left and right luffing hydraulic cylinders 103, respectively. The specific connection relationships are as follows: One end of the rod chamber connecting pipe 204 of the left hydraulic cylinder is connected to the first left chamber, and the other end is connected to the rod chamber of the left luffing hydraulic cylinder 103. One end of the rodless chamber connecting pipe 205 of the right hydraulic cylinder is connected to the first right chamber, and the other end is connected to the rodless chamber of the right luffing hydraulic cylinder 103. One end of the rodless chamber connecting pipe 206 of the left hydraulic cylinder is connected to the second left chamber, and the other end is connected to the rodless chamber of the left luffing hydraulic cylinder 103. One end of the connecting pipe 207 of the rod chamber of the right hydraulic cylinder is connected to the second right chamber, and the other end is connected to the rod chamber of the right luffing hydraulic cylinder 103.

[0032] The hydraulic coupling relationship resulting from the above cross-connection configuration is as follows: The rod chamber of the left luffing hydraulic cylinder 103 is hydraulically coupled to the rodless chamber of the right luffing hydraulic cylinder 103 through the left hydraulic cylinder rod chamber connecting pipe 204, the first left chamber, the first chamber (large diameter chamber 201), the first right chamber, and the right hydraulic cylinder rodless chamber connecting pipe 205. The rodless chamber of the left luffing hydraulic cylinder 103 is hydraulically coupled to the rod chamber of the right luffing hydraulic cylinder 103 through the left hydraulic cylinder rodless chamber connecting pipe 206, the second left chamber, the second chamber (small diameter chamber 202), the second right chamber, and the right hydraulic cylinder rod chamber connecting pipe 207.

[0033] When the loads on the two rocker arms 102 are asymmetrical, for example, when the left rocker arm is carrying a heavy load and the right rocker arm is unloaded, the pressure in the rodless chamber of the left luffing hydraulic cylinder 103 increases. This pressure is transmitted to the second left chamber via the rodless chamber connecting pipe 206, pushing the second piston downward. This, in turn, drives the first piston downward synchronously via the double-ended piston rod 203. The downward movement of the first piston compresses the hydraulic oil in the first right chamber. This pressure is transmitted to the rodless chamber of the right luffing hydraulic cylinder 103 via the rodless chamber connecting pipe 205, generating an auxiliary thrust on the right luffing hydraulic cylinder 103. This thrust produces a torque on the right rocker arm 102 opposite to the direction of the load on the left, thus automatically offsetting part of the eccentric bending moment. The reverse is also true.

[0034] The mechanism also includes a proportional control valve. This proportional control valve is connected in series in the aforementioned hydraulic interconnection pipeline system. Its function is to adjust the effective flow area ratio of the two hydraulic branches in real time based on the angle difference between the two rocker arms 102, thereby regulating the hydraulic pressure transmission ratio.

[0035] The specific structure of this proportional control valve is as follows: The proportional control valve body 300 is a metal block with a central through hole, bolted to the bottom or side of the cylinder body 200. Its interior has mutually spaced first symmetrical fluid holes 306 and second symmetrical fluid holes 307 arranged axially. Both the first symmetrical fluid holes 306 and the second symmetrical fluid holes 307 extend axially along the valve body, each having an inlet and an outlet located at the upper and lower ends (or left and right ends, depending on the axial definition) of the valve body. Both the inlet and outlet are radially penetrating through the valve body wall, intersecting with the central hole of the valve body.

[0036] Two large-diameter series pipes 301 are used to connect the proportional control valve in series to the hydraulic passage corresponding to the first chamber. One end of one large-diameter series pipe 301 is connected to the inlet of the second symmetrical fluid orifice 307, and the other end is connected to the first left chamber; one end of the other large-diameter series pipe 301 is connected to the outlet of the second symmetrical fluid orifice 307, and the other end is connected to the first right chamber. Thus, in the branch where the first chamber is located, the hydraulic oil flowing out of the first left chamber must first flow through the second symmetrical fluid orifice 307 of the proportional control valve before entering the first right chamber (or flowing in the reverse direction), and the proportional control valve constitutes a series throttling effect on this branch.

[0037] Two small-diameter series pipes 302 connect the proportional control valve in series to the hydraulic passage corresponding to the second chamber in a completely similar manner. One end of one small-diameter series pipe 302 is connected to the inlet of the first symmetrical fluid orifice 306, and the other end is connected to the second left chamber; one end of the other small-diameter series pipe 302 is connected to the outlet of the first symmetrical fluid orifice 306, and the other end is connected to the second right chamber.

[0038] The valve core 303 is cylindrical and is fitted into the central hole of the proportional regulating valve body 300 with a precision clearance fit, allowing it to slide freely along the axial direction within it. A first throttling annular groove 308, corresponding to the first symmetrical fluid orifice 306, and a second throttling annular groove 309, corresponding to the second symmetrical fluid orifice 307, are machined on the outer circumference of the valve core 303. Both the first throttling annular groove 308 and the second throttling annular groove 309 are shallow annular grooves surrounding the entire circumference of the valve core 303, with a bottom diameter smaller than the outer diameter of the valve core 303 by a predetermined depth.

[0039] It is worth mentioning that the axial width W1 of the first throttling annular groove 308 and the axial width D1 of the orifice of the first symmetrical fluid orifice 306 cooperate to form the first variable throttling orifice: when the spool valve 303 is in the middle position, the first throttling annular groove 308 and the orifice of the first symmetrical fluid orifice 306 are perfectly aligned, and the effective flow area is maximized (equal to the circumferential flow cross-sectional area of ​​the annular groove); when the spool valve 303 deviates from the middle position, the edge of the annular groove gradually obscures the orifice, and the effective flow area decreases as the deviation increases. The second throttling annular groove 309 and the second symmetrical fluid orifice 307 form the second variable throttling orifice using the same principle. The axial position and width of the two annular grooves are designed such that when the spool valve 303 moves in one direction, the effective flow area of ​​the first variable throttling orifice increases while the effective flow area of ​​the second variable throttling orifice decreases simultaneously (or vice versa), that is, the two undergo differential changes.

[0040] A valve core connecting rod 304 is integrally machined at the lower end of the spool valve core 303. A helical compression type return spring 305 is sleeved on the outer section of the valve core connecting rod 304 that protrudes from the valve body. The upper end of the return spring 305 abuts against the bottom surface of the proportional regulating valve body 300, and the lower end abuts against the stop part machined at the lower end of the valve core connecting rod 304.

[0041] The pre-compression of the return spring 305 allows the spool valve core 303 to be pushed to and held in its axial middle position when no external force is applied. At this time, the first throttling ring groove 308 is completely aligned with the first symmetrical fluid hole 306, and the second throttling ring groove 309 is completely aligned with the second symmetrical fluid hole 307. The effective flow area of ​​both flow channels is at its maximum, and the proportional control valve is in a full-flow state without throttling.

[0042] The mechanism also includes levers, supports, and an output transmission system. A bracket 405 is fixedly connected to the top of the cylinder 200 by bolts or welding. A section extends horizontally from the top of the bracket 405, and a connecting slider 407 is integrally machined or fixedly mounted on the side of the end of this horizontal section.

[0043] The lever 400 is a flat, elongated metal plate or rod with a longitudinal groove 406 machined along its width at its center. The connecting slider 407 is accommodated within the longitudinal groove 406, allowing it to slide freely longitudinally within the groove. The connecting slider 407 is elastically connected to the inner wall of the longitudinal groove 406 via a misaligned spring plate 408. When the lever 400 is subjected to longitudinal displacement, the spring plate elastically deforms to absorb the displacement and provides an elastic restoring force to return the lever 400 to its center position.

[0044] It should be understood that the connecting slider 407 and the bracket 405 together constitute the rotation fulcrum of the lever 400, and the lever 400 swings freely in the vertical plane with the axis of the connecting slider 407 as the rotation center. At the same time, the combination of the longitudinal groove 406 and the misaligned spring plate 408 provides the lever 400 with a floating degree of freedom in the longitudinal direction. The function of this floating degree of freedom is that when the force input points at both ends of the lever 400 are inconsistent in height due to assembly tolerances, thermal expansion and contraction, or deformation under force, the lever 400 can adaptively compensate through longitudinal floating, avoiding excessive additional internal stress in the transmission chain or jamming due to motion interference.

[0045] The lever 400 has an output transmission rod 409 fixed to its top. The lower end of the output transmission rod 409 is movably connected to the top surface of the lever 400 via a first ball-cage connector, and the upper end is movably connected to the lower end of the valve core connecting rod 304 via a second ball-cage connector. The two ball-cage connectors work together to allow for changes in the rod end angle during the oscillation of the lever 400, as the lever end's movement trajectory is circular while the valve core connecting rod 304's movement is linear. This avoids additional bending forces and jamming in the transmission chain.

[0046] The mechanism also includes a displacement detection and transmission mechanism. This mechanism is responsible for collecting the angular displacement of the two rocker arms 102 in a purely mechanical manner and converting it into linear displacement input at both ends of the lever 400. Its specific structure is as follows: Two angle sensing links 401 are respectively arranged on the left and right sides. One end (upper end) of each angle sensing link 401 is rotatably connected to the rocker arm hinge plate 104 on the corresponding side, and this rotatable connection point is on the same axis as the rotatable connection point between the piston end of the luffing hydraulic cylinder 103 and the rocker arm hinge plate 104—that is, the angle sensing link 401 reuses the same connecting pin between the piston end of the luffing hydraulic cylinder 103 and the rocker arm hinge plate 104, or uses an independent pin coaxial with the connecting pin. Regardless of the method used, the angle sensing link 401 will strictly follow the piston end of the luffing hydraulic cylinder 103 and swing synchronously around the same axis. Its swing angle is equal to the angle between the axis of the luffing hydraulic cylinder 103 and the top of the swivel joint 100 at the current pitch angle of the rocker arm 102. This angle corresponds one-to-one with the pitch angle of the rocker arm 102. The other end of each angle sensing link 401 is rotatably connected to the side of the cylinder body 200 through a hinge.

[0047] Each angle sensing link 401 has an internal telescopic rod 402 that can extend and retract along its axial direction. At the end of each angle sensing link 401 near the cylinder 200, an angle position conversion gear 403 is fixed by a key connection, pin connection, or integral machining. When the angle sensing link 401 drives the angle position conversion gear 403 to rotate around its lower hinge point, the trajectory of the eccentric pin in space is an arc with an eccentricity e as its radius. The left and right ends of the lever 400 are respectively connected to a flexible push-pull cable 404 via ball cage joints. The flexible push-pull cable 404 is a metal cable or thin rod with a certain axial stiffness, capable of transmitting thrust and pull forces. Each flexible push-pull cable 404 has an internal elongated groove or fork. An elongated groove refers to an elongated through hole machined at the end of the flexible push-pull cable 404 in a direction perpendicular to the cable axis; a fork refers to a fork-shaped opening formed at the end of the flexible push-pull cable 404.

[0048] An eccentric pin on the same-side angle shift gear 403 is inserted into and clearance-fitted into the elongated groove or shift fork. When the angle shift gear 403 rotates, the eccentric pin moves along an arc trajectory. Its displacement component in the axial direction of the flexible push-pull cable 404 pushes or pulls the inner wall of the elongated groove or shift fork, causing the flexible push-pull cable 404 to generate a corresponding linear displacement along its own axial direction. Meanwhile, the displacement component of the eccentric pin in the direction perpendicular to the axial direction of the flexible push-pull cable 404 slides freely in the elongated groove and is absorbed by the extension direction of the elongated groove. It is not transmitted to the flexible push-pull cable 404, and the displacement signal is transmitted to the corresponding end of the lever 400 without loss through the flexible push-pull cable 404.

[0049] To prevent the flexible push-pull cable 404 from bending laterally or becoming unstable when transmitting displacement, a guide sleeve is fitted around the outside of each flexible push-pull cable 404. The guide sleeve is a section of metal tube with a precision-machined inner hole, which is fixed with the outer wall of the bracket 405 or the cylinder 200 as the installation reference.

[0050] The mechanism also includes a micro-floating structure for the double-ended piston rod. Both pistons of the double-ended piston rod 203 have micro-conical structures and pressure-equalizing grooves machined on their outer circumferential surfaces. The micro-conical structure refers to the piston diameter gradually decreasing from the high-pressure side to the low-pressure side with an extremely small taper (e.g., 1:2000 to 1:5000), forming a micrometer-level diameter gradient. The micro-conical structure and the pressure-equalizing grooves work together to eliminate hydraulic clamping forces. Hydraulic clamping forces are radial force imbalances between the piston and cylinder bore caused by machining errors or off-center loading in hydraulic spool valves and hydraulic cylinder pistons, which can cause the piston to jam and fail to respond to small pressure differences. The micro-conical structure creates a wedge-shaped gap between the piston and cylinder bore that gradually converges from the low-pressure side to the high-pressure side. When the piston is subjected to radial off-center loading, the hydrodynamic pressure generated in the wedge-shaped gap tends to cause the piston to automatically center itself; while the pressure-equalizing grooves connect and equalize the pressure at different positions around the piston, eliminating local high-pressure points. The combined effect of these two factors allows the double-ended piston rod 203 to overcome static friction and begin to move with only a very small axial pressure difference, enabling it to float freely within a micrometer-level range.

[0051] In the first stage, the rocker arm 102 pitches and oscillates around its hinge axis with the slewing joint 100 during the luffing process. This oscillation simultaneously causes a change in the angle between the cylinder body and piston rod of the luffing hydraulic cylinder 103, which in turn causes the angle sensing link 401, coaxially mounted with the piston end of the luffing hydraulic cylinder 103, to rotate synchronously around the same axis. The rotation of the angle sensing link 401 drives the angle position conversion gear 403 fixed at its lower end to rotate synchronously. The eccentric pin on the end face of the angle position conversion gear 403 moves along an arc trajectory. The component of this arc motion in the axial direction of the flexible push-pull cable 404 pushes or pulls the flexible push-pull cable 404 to produce a linear displacement along its own axis. The magnitude of this linear displacement has a definite functional relationship with the angular displacement of the rocker arm 102. Thus, the angular displacement information of the rocker arm is converted into a linear displacement signal without loss, without the participation of any electronic sensors, and is unaffected by electromagnetic interference and temperature drift.

[0052] In the second stage, the linear displacement output by the left flexible push-pull cable 404 is transmitted to the left end of the lever 400, and the linear displacement output by the right flexible push-pull cable 404 is transmitted to the right end of the lever 400. The lever 400, with the connecting slider 407 as its fulcrum, performs a purely mechanical subtraction operation on the displacements input at both ends. If the angular displacements of the two rocker arms 102 are the same, then the linear displacements input at both ends are equal in magnitude and symmetrical in direction. The lever 400 is in equilibrium, the net rotation around the connecting slider 407 is zero, the top of the lever 400 does not move, and the output transmission rod 409 does not generate any output.

[0053] If the angular displacements of the two rocker arms 102 are different, the linear displacements input at the left and right ends will be unequal, causing the lever 400 to lose balance and generate a net rotation around the connecting slider 407. The magnitude of this net rotation is proportional to the displacement difference input on both sides. The output transmission rod 409 at the top of the lever 400 will generate a corresponding approximately linear displacement output along with this rotation.

[0054] In the third stage, the rotational output of lever 400 is transmitted to the spool valve 303 through output transmission rod 409 and valve core connecting rod 304, causing the spool valve 303 to deviate from its intermediate position. The axial offset of the spool valve 303 causes a differential change in the effective flow area of ​​the first throttling annular groove 308 relative to the first symmetrical fluid orifice 306 and the effective flow area of ​​the second throttling annular groove 309 relative to the second symmetrical fluid orifice 307, with one increasing and the other decreasing. For example, when the spool valve 303 moves upward, the alignment and overlap between the first throttling annular groove 308 and the first symmetrical fluid orifice 306 increases, increasing the effective flow area; simultaneously, the alignment and overlap between the second throttling annular groove 309 and the second symmetrical fluid orifice 307 decreases, decreasing the effective flow area.

[0055] The change in the effective flow area ratio of the two channels directly alters the hydraulic resistance ratio flowing through the two hydraulic branches. Under laminar flow conditions, the flow rate through the throttling orifice is proportional to the product of the orifice area and the pressure difference. Therefore, the change in the flow area ratio alters the flow distribution ratio through the first symmetrical fluid orifice 306 and the second symmetrical fluid orifice 307, thereby adjusting the ratio of hydraulic pressure transmitted to the left and right luffing hydraulic cylinders. Since the fixed area ratio of the double-ended piston rod 203 already provides a baseline pressure transmission ratio, the spool valve 303 only needs a slight axial offset to add an adjustment amount to the baseline ratio, thus covering the lever arm ratio requirements across the entire operating range.

[0056] In the fourth stage, after the flow area ratio adjustment in the third stage, the pressure distribution in the hydraulic interconnection circuit has approached equilibrium. However, due to the different instantaneous positions of the pistons in the two variable-amplitude hydraulic cylinders 103, the sum of the instantaneous volumes of their rod chambers and rodless chambers is not perfectly matched, and a slight volume imbalance may remain in the circuit. This volume imbalance manifests as a slight pressure difference between the four chambers in the first and second chambers. This pressure difference acts on the two pistons of the double-ended piston rod 203. Because the effective areas of the two pistons are different, even if the absolute pressures of the four chambers are close, the hydraulic resultant force acting on the two pistons is not zero. This resultant force drives the double-ended piston rod 203 to move slightly in the compensation direction, typically by a few micrometers to tens of micrometers, changing the instantaneous volume of the four chambers until the pressure difference returns to zero. This process is automatic and requires no external control intervention, allowing the system to automatically reach the final hydraulic static balance state. At the same time, the micro-conical structure and pressure equalization groove on the piston ensure that the piston rod does not jam during this slight movement.

[0057] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0058] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An anti-tipping mechanism for a self-climbing double rocker arm support structure, comprising a swivel joint (100), on both sides of which rocker arms (102) are rotatably connected, and two luffing hydraulic cylinders (103), one end of each luffing hydraulic cylinder (103) being rotatably connected to the top of the swivel joint (100), and the other end being rotatably connected to a rocker arm hinge plate (104) fixedly connected to the top of the rocker arm (102), characterized in that, Also includes: The cylinder body (200) is fixedly disposed inside the rotating section (100), and has a first chamber and a second chamber with different effective cross-sectional areas that are separated from each other. A double-ended piston rod (203) is slidably disposed in the cylinder (200), with pistons at both ends respectively sealingly fitted into the first chamber and the second chamber, dividing the first chamber into a first left chamber and a first right chamber, and dividing the second chamber into a second left chamber and a second right chamber; The hydraulic interconnection pipeline system cross-connects each chamber of the first chamber and the second chamber with the rod chamber and rodless chamber of the corresponding side of the variable amplitude hydraulic cylinder (103), so that the hydraulic pressure generated by the load difference between the two rocker arms (102) can be transmitted to each other through the double-headed piston rod (203) to automatically generate a reverse balancing torque. A proportional regulating valve is connected in series in the hydraulic interconnection pipeline system. It has a sliding valve core (303) inside, and the valve core (303) has a throttling structure for changing the effective flow area of ​​the flow channel.

2. The anti-tipping mechanism of the self-climbing double rocker arm pole-supporting structure according to claim 1, characterized in that, The hydraulic interconnection pipeline system includes: The rod chamber connecting pipe (204) of the left hydraulic cylinder is connected at one end to the first left chamber and at the other end to the rod chamber of the left luffing hydraulic cylinder (103); The rodless chamber connecting pipe (205) of the right hydraulic cylinder is connected at one end to the first right chamber and at the other end to the rodless chamber of the right luffing hydraulic cylinder (103); The rodless chamber connecting pipe (206) of the left hydraulic cylinder is connected at one end to the second left chamber and at the other end to the rodless chamber of the left luffing hydraulic cylinder (103); The rod chamber connecting pipe (207) of the right hydraulic cylinder is connected at one end to the second right chamber and at the other end to the rod chamber of the right luffing hydraulic cylinder (103).

3. The anti-tipping mechanism of the self-climbing double rocker arm pole-supporting structure according to claim 2, characterized in that, The proportional control valve includes: The proportional regulating valve body (300) is fixedly installed below or to the side of the cylinder body (200). Its interior has a first symmetrical fluid hole (306) and a second symmetrical fluid hole (307) that are spaced apart from each other along the axial direction. The first symmetrical fluid hole (306) and the second symmetrical fluid hole (307) each have an inlet and an outlet distributed along the axial direction. Two large-diameter cavity series pipes (301) are connected in series. One end of one large-diameter cavity series pipe (301) is connected to the inlet of the second symmetrical fluid hole (307) and the other end is connected to the first left cavity. One end of the other large-diameter cavity series pipe (301) is connected to the outlet of the second symmetrical fluid hole (307) and the other end is connected to the first right cavity, thereby connecting the proportional regulating valve in series into the hydraulic passage composed of the rod cavity connecting pipe (204) of the left hydraulic cylinder, the first cavity and the rodless cavity connecting pipe (205) of the right hydraulic cylinder. Two small-diameter cavity series pipes (302) are connected in series. One end of one small-diameter cavity series pipe (302) is connected to the inlet of the first symmetrical fluid hole (306) and the other end is connected to the second left cavity. One end of the other small-diameter cavity series pipe (302) is connected to the outlet of the first symmetrical fluid hole (306) and the other end is connected to the second right cavity, thereby connecting the proportional regulating valve in series into the hydraulic passage composed of the rodless cavity connecting pipe (206) of the left hydraulic cylinder, the second cavity and the rod cavity connecting pipe (207) of the right hydraulic cylinder. The slide valve core (303) is cylindrical and slidably fitted into the central hole of the proportional regulating valve body (300) along the axial direction. A first throttling ring groove (308) corresponding to the first symmetrical fluid hole (306) and a second throttling ring groove (309) corresponding to the second symmetrical fluid hole (307) are provided on its outer circumferential surface. The axial width of the first throttling ring groove (308) and the orifice width of the first symmetrical fluid hole (306) are matched to form a first variable throttling orifice. The axial width of the second throttling ring groove (309) and the orifice width of the second symmetrical fluid hole (307) are matched to form a second variable throttling orifice.

4. The anti-tipping mechanism of the self-climbing double rocker arm pole-supporting structure according to claim 3, characterized in that: A bracket (405) is fixedly connected to the top of the cylinder (200). A connecting slider (407) is provided at the top of the bracket (405). The connecting slider (407) serves as a fulcrum to support the center position of a lever (400), so that the lever (400) can swing in the vertical plane with the connecting slider (407) as the rotation center. The lever (400) has a longitudinal groove (406) at its center along its width direction. The connecting slider (407) is accommodated in the longitudinal groove (406), and the connecting slider (407) is elastically connected to the inner wall of the longitudinal groove (406) through a misaligned spring plate (408). The height of the longitudinal groove (406) is greater than the height of the connecting slider (407), thereby allowing the lever (400) to float relative to the connecting slider (407) along the extension direction of the longitudinal groove (406). The top of the lever (400) is fixed with an output transmission rod (409), and the lower end of the output transmission rod (409) is connected to the slide valve core (303). When the lever (400) swings around the connecting shaft slider (407), the angular displacement of the lever (400) is converted into the axial linear displacement of the slide valve core (303) through the output transmission rod (409).

5. The anti-tipping mechanism of the self-climbing double rocker arm force-bearing structure according to claim 4, characterized in that: The lower end of the slide valve core (303) is connected to a valve core connecting rod (304), which extends downward through the bottom of the proportional regulating valve body (300) and slides and seals with it. The lower end of the output transmission rod (409) is movably connected to the top surface of the lever (400) through the first ball cage joint, and the upper end of the output transmission rod (409) is movably connected to the lower end of the valve core connecting rod (304) through the second ball cage joint, so that the swing motion of the lever (400) can be transmitted to the valve core connecting rod (304) without jamming through the output transmission rod (409), and drive the sliding valve core (303) to move axially synchronously; A return spring (305) is sleeved on the outer section of the valve core connecting rod (304) that extends out of the proportional regulating valve body (300). The upper end of the return spring (305) abuts against the bottom surface of the proportional regulating valve body (300), and the lower end abuts against a stop on the valve core connecting rod (304).

6. The anti-tipping mechanism of the self-climbing double rocker arm pole-supporting structure according to claim 4, characterized in that, It also includes a displacement detection and transmission mechanism for transmitting the angular displacement of the two rocker arms (102) to both ends of the lever (400) in a purely mechanical manner, the mechanism comprising: Two angle sensing links (401) are provided. One end of each angle sensing link (401) is rotatably connected to the rocker arm hinge plate (104) on the corresponding side, and the rotatable connection point is located on the same axis as the piston end of the variable amplitude hydraulic cylinder (103) and the rotatable connection point of the rocker arm hinge plate (104). The other end of the angle sensing link (401) is rotatably connected to the side of the cylinder body (200). An angle position conversion gear (403) is fixedly connected to one end of each angle sensing link (401) near the cylinder (200), and an eccentric pin is provided on the end face of the angle position conversion gear (403). The left and right ends of the lever (400) are respectively connected to a flexible push-pull cable (404) through a ball cage joint. Each flexible push-pull cable (404) has an elongated groove or a fork inside. The eccentric pin on the same side angle conversion gear (403) extends into and engages with the elongated groove or fork, so that the rotational motion of the angle conversion gear (403) is converted into the linear displacement of the flexible push-pull cable (404) along its own axis through the engagement of the eccentric pin and the elongated groove or fork, thereby pushing or pulling the corresponding end of the lever (400).

7. The anti-tipping mechanism of the self-climbing double rocker arm pole-supporting structure according to claim 6, characterized in that: The lever (400) is configured to form an equal-arm or unequal-arm lever with the connecting slider (407) as the fulcrum, with its left end receiving linear displacement input from the left flexible push-pull cable (404) and its right end receiving linear displacement input from the right flexible push-pull cable (404). When the linear displacements input on both sides are equal in magnitude and symmetrical in direction, the net rotation of the lever (400) around the connecting shaft slider (407) is zero, the output transmission rod (409) does not produce displacement, and the slide valve core (303) remains in the middle position. When the linear displacements input on both sides are unequal, the lever (400) generates a net rotation proportional to the displacement difference, which drives the output transmission rod (409) to generate a corresponding axial displacement, driving the spool valve (303) to deviate from the middle position, causing the effective flow area ratio of the first variable throttle orifice and the second variable throttle orifice to change in accordance with the displacement difference, thereby adaptively adjusting the hydraulic flow resistance ratio flowing through the first symmetrical fluid orifice (306) and the second symmetrical fluid orifice (307), and realizing the adaptive matching of the hydraulic pressure transmission ratio with the angle difference of the rocker arms on both sides.

8. The anti-tipping mechanism of the self-climbing double rocker arm pole-supported force-bearing structure according to claim 1, characterized in that: The outer circumferential surfaces of the two pistons of the double-ended piston rod (203) are provided with micro-inverted cone structures and / or pressure equalization grooves. The micro-inverted cone structure makes the piston diameter gradually decrease from the high-pressure side to the low-pressure side. The pressure equalization groove extends along the circumference of the piston. The two work together to eliminate the hydraulic clamping force caused by machining errors or off-center loads, so that the double-ended piston rod (203) can float freely within a micrometer range under the four-chamber pressure difference of the first chamber and the second chamber. This automatically compensates for the displacement difference generated by the two variable amplitude hydraulic cylinders (103) when the rocker arm (102) is at different angles, maintains the continuity and pressure balance of the hydraulic interconnection circuit, and avoids the phenomenon of air suction or oil trapping in the system.

9. The anti-tipping mechanism of the self-climbing double rocker arm pole-supporting structure according to claim 6, characterized in that: The angle sensing link (401) is provided with a telescopic rod (402) that can extend and retract along its axial direction.

10. The anti-tipping mechanism of the self-climbing double rocker arm pole-supporting structure according to claim 6, characterized in that: Each flexible push-pull cable (404) is fitted with a guide sleeve fixed to the cylinder (200) or bracket (405), the guide sleeve constraining the flexible push-pull cable (404) to slide linearly along its axial direction only.

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