A lifting hole protection device, a protection method and an installation method of the protection device

Abstract

A lifting hole protection device, protection method and installation method of the protection device mainly include a method. An electric push rod is used to drive a folding guardrail to lift upwards, gradually opening the cover plate to achieve primary protection; the electric push rod continues to extend, and the folding guardrail continues to rise. When the pulley is located at the lower end of the telescopic guardrail, the pulley will support the telescopic guardrail to rise; after the folding guardrail rises to a certain height, it will drive the drawable guardrail to move upwards. Finally, the electric push rod stops moving; at this time, the folding guardrail and the telescopic guardrail rise to the upper limit position, and the upper ends of the folding guardrail and the telescopic guardrail are flush. The drawable guardrail protects the empty area between the folding guardrail and the mounting plate foundation. The lifting hole protection device, protection method and installation method of the protection device provided by the present invention are simple, safe and convenient to operate.

Description

Technical Field

[0001] The present invention relates to a guardrail for a lifting hole, in particular to a protection device for a lifting hole, a protection method and an installation method of the protection device. Background Art

[0002] During the construction process, when the main building is completed, a lifting hole is generally designed on the second floor for convenient material transfer. The lifting hole is currently only equipped with a double-door hand-held cover plate. The cover plate is heavy and there is no protective fence, posing a safety hazard of falling from a height.

[0003] The patent "Double-door Cover Plate for Lifting Hole" with the application number "201020674772.0" forms a fence by opening the upper and lower cover plates to ensure safety. However, as described above, the cover plate is heavy and very difficult to lift by hand, posing a safety risk.

[0004] In addition, the existing lifting holes are roughly square holes, with a length and width of about 1500 mm. That is, the width of each cover plate is about 750 mm. The height after the cover plate is lifted must not exceed 750 mm. According to the national standard, the height of the guardrail is not less than 1050 mm. Therefore, simply flipping the cover up to make a guardrail cannot meet the height requirements. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a protection device for a lifting hole, a protection method and an installation method of the protection device, which can facilitate hoisting and ensure safety during hoisting.

[0006] To solve the above technical problem, the technical solution adopted by the present invention is:

[0007] A protection device for a lifting hole includes a mounting plate base. Cover plates are hinged to the left and right of the mounting plate base. A telescopic guardrail is slidably arranged on the cover plates. Side guardrails are arranged in the front and back of the mounting plate base. The side guardrails include mounting brackets. Electric push rods are installed on the mounting brackets. The electric push rods are connected to and drive the folding guard rods to move up and down. A pull-out guardrail is slidably arranged at the lower end of the folding guard rods. When the folding guard rods are lifted at the first stage, the folding guard rods push open the left and right cover plates. When the folding guard rods are lifted at the second stage, the telescopic guardrail extends out of the cover plates, and the pull-out guardrail is lifted upward to form a side guard with the folding guard rods.

[0008] The cover plate includes a panel. Limit plates are arranged on the left and right of the back of the panel, and a chute is arranged at the upper end. The telescopic guardrail is slidably matched with the cover plate through the limit plates and the chute. A first support is arranged at the lower part of the back of the panel. A tension spring is connected between the first support and the telescopic guardrail. A rotating shaft is installed at the bottom of the back of the panel, and the rotating shaft is rotatably connected to the mounting plate base.

[0009] The folding guardrail includes a trapezoidal frame. A retaining sleeve is provided inside the trapezoidal frame. Folding guardrails are hinged to the left and right on the outer side of the upper end of the trapezoidal frame, and the folding guardrails are pushed open by the retracting elastic pieces at the lower part; pulleys are fixed to the left and right on the outer side of the lower end of the trapezoidal frame. The pulleys are located under the telescopic guardrail and lift the telescopic guardrail during the lifting process.

[0010] The drawable guardrail includes a back plate. A cross beam is fixed to the lower end of the back plate. Hooks are provided on the left and right of the cross beam, and the limit switch is triggered after the hooks are lifted; a retaining rod is installed at the upper end of the cross beam, and the retaining rod is slidably matched with the through hole or the retaining sleeve of the trapezoidal frame; the retaining rods on the left and right sides are limited by limit bolts.

[0011] A method for protecting a lifting hole includes the following steps:

[0012] Step 1), when opening, start the electric push rod. The electric push rods on the left and right drive the folding guardrail to lift upward. Since the upper end of the folding guardrail is narrow and the lower end is wide, when the folding guardrail moves upward, the folding guardrail can gradually open the cover plate in a gradual change manner;

[0013] Step 2), as the cover plate opens, the folding guardrail gradually rotates outward from the state of folding inward under the action of the retracting elastic piece; when the cover plate rotates to the vertical state, the upper end of the cover plate is tightly pressed by the folding guardrail to form a primary protection;

[0014] Step 3), when secondary protection is required, the electric push rod continues to extend, and the folding guardrail continues to rise. When the pulley is located at the lower end of the telescopic guardrail, the pulley will support the telescopic guardrail and lift it upward; and when the folding guardrail rises to a certain height, it will drive the drawable guardrail to move upward; finally, when the hook touches the limit switch, the electric push rod stops moving; at this time, the folding guardrail and the telescopic guardrail rise to the upper limit position, the upper ends of the folding guardrail and the telescopic guardrail are kept flush, and the drawable guardrail protects the empty area between the folding guardrail and the mounting plate base;

[0015] Step 4), when closing is required, the electric push rod contracts, and the folding guardrail gradually descends. When the folding guardrail descends, the telescopic guardrail and the drawable guardrail both gradually move downward; when the telescopic guardrail lands on the first support, it stops moving and is supported by the first support; when the lower end of the drawable guardrail lands on the mounting bracket, the drawable guardrail stops moving and is supported by the mounting bracket; at this time, due to the effect of the folding guardrail, the left and right cover plates still remain vertical;

[0016] Step 5), the electric push rod continues to contract, and the left and right cover plates rotate inward and gradually close; due to the extrusion of the two cover plates, the folding guardrail gradually folds downward and squeezes the retracting elastic piece; finally, the two cover plates close and fall on the top of the folding guardrail to complete the closing.

[0017] An installation method for a lifting hole protection device includes the following steps:

[0018] Step 1), Cover plate installation: There are four bearing seats on the installation plate foundation, arranged in pairs left and right at intervals. The cover plate is installed on the bearing seats through a rotating shaft and bearings, and positioned using a retaining ring; the cover plate is installed on both sides simultaneously, and the opening and closing gaps and interferences are adjusted through the fixing screws of the bearing seats.

[0019] Step 2), Install the telescopic guardrail: Insert the telescopic guardrail into the cover plate and insert the limit pin; install a tension spring between the limit pin and the bottom of the cover plate to lock the telescopic guardrail into the cover plate.

[0020] Step 3), Electric push rod installation: Install the electric push rod into the installation bracket; install the installation bracket into the installation plate foundation.

[0021] Step 4), Side guardrail installation: Install the retracting spring piece onto the folding guard rod, install the folding guard rod, and test that the pressure for pressing back the folding guard rod is greater than 20 kg, and the pressure is adjusted through the angle of the retracting spring piece; insert the drawable guardrail through the corresponding holes, and lock the limit screws on the two stop rods on both sides of the drawable guardrail; install the assembled side guardrail onto the electric push rod, and retract the electric push rod to the shortest position, at this time the cover plate is fully closed.

[0022] A lifting hole protection device, protection method and protection device installation method of the present invention have the following technical effects:

[0023] 1), The folding guard rod is pushed up and down by the electric push rod, and the folding guard rod is lifted twice. The cover plate and the telescopic guardrail form the left and right guardrails; the folding guard rod and the drawable guardrail form the front and rear guardrails; it is not only convenient to operate, but also safer, and the height of the guardrail meets the requirements.

[0024] 2), By adopting a trapezoidal frame, the cover plate can be gradually pushed open to ensure the stability of the cover plate opening; by setting an elastic folding guard rod, the stability after the cover plate is fully opened can be ensured; by setting pulleys, the telescopic guardrail can be lifted while the device is lifting itself, making the structure more compact; by setting the position of the pulleys, the height from the pulley to the top of the trapezoidal frame is kept the same as the height of the telescopic guardrail, so that the upper ends of the guardrails around are flush after the final lifting.

[0025] 3), Through the drawable guardrail with a hook at the lower part, the limit switch can be automatically triggered during lifting to stop the electric push rod. Description of the Drawings

[0026] The present invention will be further described below in conjunction with the drawings and embodiments:

[0027] Figure 1 It is a schematic diagram of the first state of the present invention.

[0028] Figure 2Schematic diagram of the second state of the present invention.

[0029] Figure 3 Schematic diagram of the third state of the present invention.

[0030] Figure 4 is Figure 3 Partial enlarged schematic diagram at position A in

[0031] Figure 5 Schematic diagram of the structure of the cover plate in the present invention.

[0032] Figure 6 Schematic diagram of the connection between the cover plate and the telescopic guardrail in the present invention.

[0033] Figure 7 Schematic diagram of the connection of the cover plate of the present invention installed on the mounting plate base.

[0034] Figure 8 Schematic diagram of the installation of the electric push rod of the present invention.

[0035] Figure 9 Schematic diagram of the folding guardrail at the mounting plate base in the present invention.

[0036] Figure 10 is Figure 9 Partial enlarged schematic diagram at position B in

[0037] Figure 11 Schematic diagram of the first state of the side guardrail in the present invention.

[0038] Figure 12 Schematic diagram of the second state of the side guardrail in the present invention.

[0039] Figure 13 Schematic diagram of the third state of the side guardrail in the present invention.

[0040] Figure 14 Schematic diagram of the closed state of the present invention.

[0041] In the figure: mounting plate base 1, cover plate 2, telescopic guardrail 3, side guardrail 4, mounting bracket 5, electric push rod 6, folding guardrail 7, pull-out guardrail 8, limit switch 9, panel 2.1, limit plate 2.2, chute 2.3, first support 2.4, tension spring 2.5, rotating shaft 2.6, trapezoidal frame 7.1, folding guard bar 7.2, retracting spring piece 7.3, pulley 7.4, retaining sleeve 7.5, back plate 8.1, cross beam 8.2, hook 8.3, stop bar 8.4, limit bolt 8.5. Detailed implementation manners

[0042] Such as Figures 1-3As shown in the figure, a secondary lifting cover plate for a safe and labor-saving lifting hole includes a mounting plate base 1, which is fixed on the base of the lifting hole. The mounting plate base 1 is hinged with cover plates 2 on the left and right. When the two cover plates 2 are horizontal, they close the lifting hole. When the two cover plates 2 are flipped to the vertical state, they form left and right guardrails. A telescopic guardrail 3 is slidably arranged on the cover plate 2, and the telescopic guardrail 3 can slide up and down along the cover plate 2. Side guardrails 4 are provided at the front and rear of the mounting plate base 1. When the side guardrails 4 descend to the lower limit position, they can support the cover plate 2. When the side guardrails 4 ascend to the upper limit position, they can form front and rear guardrails.

[0043] As Figures 1-3 , Figures 11-13 shown, the side guardrail 4 includes a mounting bracket 5, and the mounting bracket 5 is fixed to the lower part of the mounting plate base 1. An electric push rod 6 is installed on the mounting bracket 5, and the electric push rod 6 is a three-stage electric push rod. The electric push rod 6 is fixedly connected to the upper end of the folding guard rod 7 and drives the folding guard rod 7 to move up and down. A pull-out guardrail 8 is slidably arranged at the lower end of the folding guard rod 7. When the folding guard rod 7 is lifted at the first stage, the folding guard rod 7 pushes open the cover plates 2 on the left and right, the cover plates 2 form left and right guardrails, and the folding guard rod 7 forms front and rear guardrails. When the folding guard rod 7 is lifted at the second stage, the telescopic guardrail 3 extends out of the cover plate 2. The telescopic guardrail 3 and the cover plate 2 are arranged up and down and form left and right guardrails. The pull-out guardrail 8 is lifted up a certain height. The folding guard rod 7 and the pull-out guardrail 8 are arranged up and down and form front and rear guardrails.

[0044] As Figures 5-7 shown, the cover plate 2 includes a panel 2.1. Limit plates 2.2 are provided on the left and right of the back of the panel 2.1, and a chute 2.3 is provided at the upper end. The telescopic guardrail 3 is limited and guided left and right by the limit plates 2.2, and the telescopic guardrail 3 is limited and guided front and rear by the chute 2.3. In this way, the telescopic guardrail 3 can move up and down along the panel 2.1. A first support 2.4 is provided at the lower part of the back of the panel 2.1, and the first support 2.4 is used to support the telescopic guardrail 3 when the telescopic guardrail 3 retracts. A tension spring 2.5 is connected between the first support 2.4 and the telescopic guardrail 3. The tension spring 2.5 can make the telescopic guardrail 3 reset to its original position when the cover plate 2 is closed later. A rotating shaft 2.6 is installed at the bottom of the back of the panel 2.1. The rotating shaft 2.6 is rotatably connected to a bearing seat on the mounting plate base 1 through a bearing, and the bearing seat is installed on the fixing plate of the mounting plate base 1.

[0045] As Figure 11As shown in the figure, the folding guardrail 7 includes a trapezoidal frame 7.1. The trapezoidal frame 7.1 can gradually push open the cover plate 2 when rising to ensure stability. A retaining sleeve 7.5 is provided inside the trapezoidal frame 7.1, and the retaining sleeve 7.5 and the trapezoidal frame 7.1 form a guardrail. On the outer sides of the upper end of the trapezoidal frame 7.1, folding guardrails 7.2 are hinged left and right. The folding guardrails 7.2 are pushed open by the retracting elastic pieces 7.3 at the lower part. After the first-level lifting of the folding guardrail 7, the folding guardrails 7.2 can be abutted against the cover plate 2 to keep the cover plate 2 vertically stable without swaying. On the outer sides of the lower end of the trapezoidal frame 7.1, pulleys 7.4 are fixed left and right. The pulleys 7.4 are located at the lower part of the telescopic guardrail 3. When the folding guardrail 7 is lifted to the second level, the pulleys 7.4 will push the telescopic guardrail 3 upward.

[0046] As Figure 11 shown, the drawable guardrail 8 includes a back plate 8.1. A cross beam 8.2 is fixed at the lower end of the back plate 8.1. Hooks 8.3 are provided on the left and right of the cross beam 8.2. When the folding guardrail 7 is lifted to the upper limit position at the second level, the limit switch 9 is triggered on the hooks 8.3 to stop the electric push rod 6. A stop rod 8.4 is installed at the upper end of the cross beam 8.2. The stop rod 8.4 serves as a guardrail to ensure safety. The stop rod 8.4 is in sliding fit with the through hole or the retaining sleeve 7.5 of the trapezoidal frame 7.1, which enables the drawable guardrail 8 to move up and down relative to the folding guardrail 7. The stop rods 8.4 on the left and right sides can be threadedly connected with the limit bolts 8.5 after passing through the through holes of the trapezoidal frame 7.1. In this way, the limit bolts 8.5 limit to prevent the drawable guardrail 8 from detaching from the folding guardrail 7, and at the same time facilitate driving the drawable guardrail 8 to lift when the folding guardrail 7 is lifted to the second level.

[0047] A method for protecting a lifting hole includes the following steps:

[0048] Step 1), the program controls the electric push rod 6 to rise. The electric push rods 6 on the left and right sides drive the folding guardrail 7 to lift upward. Since the upper end of the folding guardrail 7 is narrow and the lower end is wide, when the folding guardrail 7 moves upward, the folding guardrail 7 can gradually open the cover plate 2 in a gradual change manner;

[0049] Step 2), as the cover plate 2 opens, the folding guardrails 7.2 gradually rotate outward from the inward-folded state under the action of the retracting elastic pieces 7.3; when the cover plate 2 rotates to the vertical state, the upper end of the cover plate 2 is tightly abutted by the folding guardrails 7.2 to form a primary protection;

[0050] Step 3), when secondary protection is required, the electric push rod 6 continues to extend, and the folding guardrail 7 continues to rise. When the pulley 7.4 is located at the lower end of the telescopic guardrail 3, the pulley 7.4 will support the telescopic guardrail 3 and lift it upward; when the folding guardrail 7.2 rises to a certain height, it will drive the drawable guardrail 8 to move upward; finally, when the hook 8.3 touches the limit switch 9, the electric push rod 6 stops moving; at this time, the folding guardrail 7 and the telescopic guardrail 3 rise to the upper limit position, and the upper ends of the folding guardrail 7 and the telescopic guardrail 3 are kept flush, and the drawable guardrail 8 protects the empty area between the folding guardrail 7 and the mounting plate base 1;

[0051] Step 4), when closing is required, the electric push rod 6 contracts, and the folding guardrail 7 gradually descends. When the folding guardrail 7 descends, both the telescopic guardrail 3 and the drawable guardrail 8 gradually move downward; when the telescopic guardrail 3 lands on the first support 2.4, it stops moving and is supported by the first support 2.4; when the lower end of the drawable guardrail 8 lands on the mounting bracket 5, the drawable guardrail 8 stops moving and is supported by the mounting bracket 5; at this time, due to the effect of the folding guardrail 7.2, the left and right cover plates 2 still remain vertical;

[0052] Step 5), the electric push rod 6 continues to contract, and the left and right cover plates 2 rotate inward and gradually close; due to the extrusion of the two cover plates 2, the folding guardrail 7.2 gradually folds downward and closes and squeezes the retracting spring piece 7.3; finally, the two cover plates 2 close and land on the top of the folding guardrail 7 to complete the closing.

[0053] An installation method of a lifting hole protection device includes the following steps:

[0054] Step 1), cover plate installation: There are four bearing seats on the mounting plate base 1, arranged in pairs left and right at intervals. The cover plate 2 is installed on the bearing seats through the rotating shaft 2.6 and bearings, and positioned with a retaining ring; the cover plate 2 is installed on both sides at the same time, and the opening and closing gaps and interferences are adjusted through the bearing seat fixing screws;

[0055] Step 2), installing the telescopic guardrail: Insert the telescopic guardrail 3 into the cover plate 2 and insert the limit pin; and install a tension spring 2.5 between the limit pin and the bottom of the cover plate 2 to lock the telescopic guardrail 3 into the cover plate 2.

[0056] Step 3), electric push rod installation: Install the electric push rod 6 into the mounting bracket 5; install the mounting bracket 5 into the mounting plate base 1.

[0057] Step 4), Side guardrail installation: Install the retracting spring piece 7.3 to the folding guardrail 7, install the folding guardrail 7, and test that the pressure for pressing back the folding guardrail 7 is greater than 20 kg, and the pressure is adjusted through the angle of the retracting spring piece 7.3; Insert the pull-out guardrail 8 into the corresponding holes, and lock the limit screws 8.5 on the two stop bars 8.4 on both sides of the pull-out guardrail 8; Install the assembled side guardrail 4 to the electric push rod 6, and retract the electric push rod 6 to the shortest position, at this time the cover plate 2 is completely closed.

Claims

1. A lifting hole protection device, characterized in that: It includes a mounting plate base (1). A cover plate (2) is hinged to the left and right of the mounting plate base (1). A telescopic guardrail (3) is slidably arranged on the cover plate (2). Side guardrails (4) are arranged in the front and back of the mounting plate base (1). The side guardrails (4) include mounting brackets (5). Electric push rods (6) are installed on the mounting brackets (5). The electric push rods (6) are connected to folding guard rods (7) and drive the folding guard rods (7) to move up and down. A pull-out guardrail (8) is slidably arranged at the lower end of the folding guard rod (7). When the folding guard rod (7) is lifted for the first stage, the folding guard rod (7) pushes open the cover plates (2) on the left and right. When the folding guard rod (7) is lifted for the second stage, the telescopic guardrail (3) extends out of the cover plate (2), and the pull-out guardrail (8) is lifted upward to form side protection with the folding guard rod (7). The cover plate (2) includes a panel (2.1). Limit plates (2.2) are arranged on the left and right of the back of the panel (2.1), and a chute (2.3) is arranged at the upper end. The telescopic guardrail (3) is slidably matched with the cover plate (2) through the limit plates (2.2) and the chute (2.3). A first support (2.4) is arranged at the lower part of the back of the panel (2.1). A tension spring (2.5) is connected between the first support (2.4) and the telescopic guardrail (3). A rotating shaft (2.6) is installed at the bottom of the back of the panel (2.1), and the rotating shaft (2.6) is rotatably connected to the mounting plate base (1). The folding guard rod (7) includes a trapezoidal frame (7.1). A retaining sleeve (7.5) is arranged inside the trapezoidal frame (7.1). Folding guard rods (7.2) are hinged to the left and right of the outer side of the upper end of the trapezoidal frame (7.1), and the folding guard rods (7.2) are pushed open by the retracting elastic pieces (7.3) at the lower part. Pulleys (7.4) are fixed to the left and right of the outer side of the lower end of the trapezoidal frame (7.1). The pulleys (7.4) are located below the telescopic guardrail (3) and lift the telescopic guardrail (3) during the lifting process. The pull-out guardrail (8) includes a back plate (8.1). A cross beam (8.2) is fixed to the lower end of the back plate (8.1). Hooks (8.3) are arranged on the left and right of the cross beam (8.2). When the hooks (8.3) move upward, a limit switch (9) is triggered. A stop rod (8.4) is installed at the upper end of the cross beam (8.2). The stop rod (8.4) is slidably matched with the through holes or the retaining sleeve (7.5) of the trapezoidal frame (7.1). The stop rods (8.4) on the left and right sides are limited by limit bolts (8.5).

2. A method for protecting with a lifting hole protection device according to claim 1, comprising the following steps: Step 1): When opening, start the electric push rods (6). The electric push rods (6) on the left and right drive the folding guard rods (7) to lift upward. Since the upper end of the folding guard rod (7) is narrow and the lower end is wide, when the folding guard rod (7) moves upward, the folding guard rod (7) gradually opens the cover plate (2) in a gradual change manner. Step 2), as the cover plate (2) opens, the folding guard bar (7.2) gradually rotates outward from the inward-folded state under the action of the retracting spring piece (7.3); when the cover plate (2) rotates to the vertical state, the upper end of the cover plate (2) is pressed tightly by the folding guard bar (7.2) to form primary protection; Step 3), when secondary protection is required, the electric push rod (6) continues to extend, and the folding guard bar (7) continues to rise. When the pulley (7.4) is located at the lower end of the telescopic guard rail (3), the pulley (7.4) will support the telescopic guard rail (3) to rise; after the folding guard bar (7) rises to a certain height, it will drive the pull-out guard rail (8) to move upward; finally, when the hook (8.3) touches the limit switch (9), the electric push rod (6) stops; at this time, the folding guard bar (7) and the telescopic guard rail (3) rise to the upper limit position, and the upper ends of the folding guard bar (7) and the telescopic guard rail (3) are kept flush, and the pull-out guard rail (8) protects the empty area between the folding guard bar (7) and the mounting plate base (1); Step 4), when closing is required, the electric push rod (6) contracts, and the folding guard bar (7) gradually descends. When the folding guard bar (7) descends, the telescopic guard rail (3) and the pull-out guard rail (8) both gradually move downward; when the telescopic guard rail (3) lands on the first support (2.4), it stops and is supported by the first support (2.4); when the lower end of the pull-out guard rail (8) lands on the mounting bracket (5), the pull-out guard rail (8) stops and is supported by the mounting bracket (5); at this time, due to the action of the folding guard bar (7), the left and right cover plates (2) still remain vertical; Step 5), the electric push rod (6) continues to contract, and the left and right cover plates (2) rotate inward and gradually close; due to the extrusion of the two cover plates (2), the folding guard bar (7.2) gradually folds downward and squeezes the retracting spring piece (7.3); finally, the two cover plates (2) are closed and fall on the top of the folding guard bar (7) to complete the closing.

3. A method for installing a lifting hole protection device according to claim 1, comprising the following steps: Step 1), cover plate installation: There are four bearing seats on the mounting plate base (1), arranged in pairs left and right at intervals. The cover plate (2) is installed on the bearing seats through the rotating shaft (2.6) and bearings, and positioned with a retaining ring; the cover plate (2) is installed on both sides simultaneously; Step 2), installing the telescopic guard rail: Insert the telescopic guard rail (3) into the cover plate (2) and insert the limit pin; and install a tension spring (2.5) between the limit pin and the bottom of the cover plate (2) to lock the telescopic guard rail (3) into the cover plate (2); Step 3), electric push rod installation: Install the electric push rod (6) into the mounting bracket (5); install the mounting bracket (5) into the mounting plate base (1); Step 4), Side guardrail installation: Install the retracting spring piece (7.3) to the folding guardrail (7), install the folding guardrail (7), and test that the pressure for pressing back the folding guardrail (7) is greater than 20 kg, and the pressure is adjusted by the angle of the retracting spring piece (7.3); Pass the retractable guardrail (8) through the corresponding through hole or sleeve (7.5), and lock the limit bolts (8.5) on the two side bars (8.4) on both sides of the retractable guardrail (8); Install the assembled side guardrail (4) to the electric push rod (6), and retract the electric push rod (6) to the shortest position, at this time the cover plate (2) is completely closed.

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