Intelligent monitoring device for floor safety protective door of construction elevator
By installing intelligent monitoring devices on the safety protective doors of construction elevators, the safety hazards caused by construction workers' forgetting to close the protective doors are solved, and higher safety and stability are achieved.
Patent Information
- Application Number
- CN202421954325.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-13
- Publication Date
- 2025-06-20
- Estimated Expiration
- 2034-08-13
AI Technical Summary
Construction personnel are prone to forget to close the safety protection door when using construction elevators, resulting in safety hazards.
Design an intelligent monitoring device for floor safety protective doors for construction elevators. By installing switch components and monitoring components on the door frame, the closed status of the protective door panel is monitored, and a warning is issued when it is not completely closed to ensure that the protective door panel is locked.
It effectively avoids safety hazards caused by the protection door not being closed, and ensures the safety of the construction site and the stability of use.
Smart Images

Figure CN223002533U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of safety protection doors, in particular to an intelligent monitoring device for the floor safety protection door of a construction elevator. Background Technique
[0002] During the construction of high-rise buildings, construction elevators are usually built on the outside of the building wall to meet the vertical transportation needs of the construction site. The entrances and exits between the building floors and the construction elevator are all located at the edge of the building body. Therefore, to ensure the safety of construction workers and reduce the occurrence of safety accidents such as falling from a height, construction workers need to install safety protection doors at the entrances and exits of the construction elevator on each floor. The safety protection door is usually in a closed state and can only be opened for passage after the construction elevator reaches the corresponding floor. The safety protection door includes a door frame for installation on the building body, and a first protection door panel and a second protection door panel respectively hinged to the door frame. A safety lock for opening or closing the safety protection door is connected between the two protection door panels.
[0003] However, after construction workers reach the corresponding floor by the construction elevator, open the safety protection door and enter the building body, it is easy to forget to close the safety protection door in time. The unclosed safety protection door has certain safety hazards. Therefore, an intelligent monitoring device for the floor safety protection door of a construction elevator is proposed to solve the above problems. Summary of the Utility Model
[0004] In order to make up for the deficiencies of the prior art and solve the problem that after construction workers reach the corresponding floor by the construction elevator, open the safety protection door and enter the building body, it is easy to forget to close the safety protection door in time, and the unclosed safety protection door has certain safety hazards, the utility model proposes an intelligent monitoring device for the floor safety protection door of a construction elevator.
[0005] The technical solution adopted by the utility model to solve its technical problems is: an intelligent monitoring device for the floor safety protection door of a construction elevator described in the utility model includes a door frame. On both sides inside the door frame, a first protection door panel and a second protection door panel are respectively hinged. A switch assembly is installed on the first protection door panel and the second protection door panel. The first protection door panel and the second protection door panel are opened or closed through the switch assembly. A monitoring assembly is arranged on the side of the switch assembly to monitor whether the switch assembly is completely closed through the monitoring assembly. When the first protection door panel and the second protection door panel are closed, the first protection door panel and the second protection door panel are locked together through the switch assembly, thereby preventing the first protection door panel and the second protection door panel from being opened. The monitoring assembly judges whether the switch assembly has been completely closed, and gives a warning when it is not completely closed to remind the construction workers to close the protection door in time and avoid potential safety hazards.
[0006] Preferably, the switch assembly includes a first fixed plate and a second fixed plate. The first fixed plate is fixedly connected to the first protective door panel, and the second fixed plate is fixedly connected to the second protective door panel. The first fixed plate and the second fixed plate are arranged opposite to each other. A limiting ring is fixedly installed on the first fixed plate, and a plug rod is installed in the limiting ring. A dial rod is fixedly connected to the middle of the plug rod. A sleeve rod is fixedly connected to the middle position of the second fixed plate. The plug rod can slide along the middle of the limiting ring and be inserted into the inside of the sleeve rod. By setting the switch assembly, the first protective door panel and the second protective door panel are locked to ensure the use safety.
[0007] Preferably, the monitoring assembly includes a fixed block. The fixed block is fixedly connected to the inside of the end of the sleeve rod far from the plug rod. A through hole is opened in the middle of the fixed block, and a connecting rod is slidably installed in the through hole. A push plate is fixedly connected to the end of the connecting rod close to the plug rod, and a pressing block is fixedly connected to the other end of the connecting rod. A first spring is fixedly installed between the fixed block and the push plate. A touch switch is fixedly installed at the innermost side of the end of the sleeve rod far from the plug rod. A controller, a warning light, and an alarm are fixedly installed in sequence from right to left at the position adjacent to the second fixed plate on the side wall of the second protective door panel. The touch switch, the warning light, and the alarm are respectively electrically connected to the controller. By setting the monitoring assembly, it is judged whether it is completely closed, and a warning is given when it is not completely closed to remind the construction personnel to close the protective door in time to avoid potential safety hazards.
[0008] Preferably, there are two limiting rings, which are respectively fixedly connected to the two transverse ends of the first fixed plate. The dial rod is arranged in the middle position between the two limiting rings, thereby restricting the movement range of the plug rod.
[0009] Preferably, a limiting assembly is arranged on the first fixed plate. The position of the plug rod and the dial rod is restricted by the limiting assembly. The limiting assembly includes two relatively arranged U-shaped blocks. The U-shaped blocks are fixedly connected to the first fixed plate. Limiting blocks are symmetrically arranged in the middle of the two U-shaped blocks. Through slots are respectively opened in the middle of the two limiting blocks. A rotating shaft is movably installed in the through slots. The two ends of the rotating shaft are respectively rotatably installed in the installation holes opened on the two side edges of the U-shaped block. A second spring is fixedly installed on the inner wall of the through slot, and the end of the second spring abuts against the side wall of the rotating shaft. Sliders are symmetrically fixedly connected to the upper and lower ends of the middle position of the rotating shaft. Slide grooves are respectively opened in the middle positions of the upper and lower inner walls of the through slot. The sliders are slidably arranged in the slide grooves. The position of the dial rod is restricted by the limiting assembly, thereby preventing the plug rod from disengaging from the inside of the sleeve rod and ensuring that the switch assembly can completely lock the first protective door panel and the second protective door panel.
[0010] Preferably, the two ends of the rotating shaft extend outwards to the outside of the two ends of the U-shaped block, and torsion springs are respectively fixedly installed at the two ends of the rotating shaft. By setting the torsion springs, the rotating shaft can be reset.
[0011] Preferably, the tops of the opposite sides of the two limiting blocks are arranged in an inclined shape, facilitating the dial rod to squeeze into the inner position from the outside of the two limiting blocks, and restricting the movement of the dial rod through the limiting blocks.
[0012] Preferably, blocking rods are symmetrically and fixedly connected to the opposite side walls of the two U-shaped blocks, and the blocking rods abut against the bottoms of the limiting blocks. By providing the blocking rods, the rotation direction of the limiting blocks is restricted, and the limiting blocks are kept in a position perpendicular to the U-shaped blocks.
[0013] The beneficial effects of the present utility model are as follows:
[0014] 1. By providing a switch assembly and a monitoring assembly, when the first protective door panel and the second protective door panel are closed, the first protective door panel and the second protective door panel are locked together through the switch assembly, thereby preventing the first protective door panel and the second protective door panel from being opened. The monitoring assembly determines whether the switch assembly has been completely closed, and gives a warning when it is not completely closed to remind the construction workers to close the protective door in time, avoiding potential safety hazards.
[0015] 2. By restricting the positions of the insertion rod and the dial rod through the limiting assembly, the insertion rod is always inserted inside the sleeve rod, preventing the insertion rod from accidentally falling out of the sleeve rod, and ensuring that the switch assembly can stably lock the first protective door panel and the second protective door panel together. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.
[0017] Figure 1 It is a schematic diagram of the overall structure of Embodiment 1;
[0018] Figure 2 It is a partial cross-sectional view of Embodiment 1;
[0019] Figure 3 It is for Figure 2 the enlarged schematic diagram of the structure at A in
[0020] Figure 4 It is a schematic diagram of the structure of the limiting assembly of Embodiment 1;
[0021] Figure 5 It is a cross-sectional view of the limiting block of Embodiment 1.
[0022] In the figure: 1, door frame; 2, first protective door panel; 3, second protective door panel; 4, switch assembly; 41, first fixing plate; 42, second fixing plate; 43, limiting ring; 44, inserting rod; 45, lever; 46, sleeve rod; 5, monitoring assembly; 51, controller; 52, warning light; 53, alarm; 54, pushing plate; 55, first spring; 56, fixing block; 57, connecting rod; 58, pressing block; 59, through hole; 510, touch switch; 6, limiting assembly; 61, U-shaped block; 62, limiting block; 63, long groove; 64, second spring; 65, torsion spring; 66, mounting hole; 67, rotating shaft; 68, slider; 69, sliding groove. Specific implementation mode
[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.
[0024] Embodiment 1
[0025] Please refer to Figures 1-5 As shown, an intelligent monitoring device for the floor safety protection door of a construction elevator includes a door frame 1. On both sides inside the door frame 1, a first protective door panel 2 and a second protective door panel 3 are respectively hinged. A switch assembly 4 is installed on the first protective door panel 2 and the second protective door panel 3. The first protective door panel 2 and the second protective door panel 3 are opened or closed through the switch assembly 4. A monitoring assembly 5 is arranged on the side of the switch assembly 4 to monitor whether the switch assembly 4 is completely closed. During operation, when the first protective door panel 2 and the second protective door panel 3 are closed, the first protective door panel 2 and the second protective door panel 3 are locked together through the switch assembly 4, thereby preventing the first protective door panel 2 and the second protective door panel 3 from being opened. The monitoring assembly 5 judges whether the switch assembly 4 has been completely closed, and gives a warning when it is not completely closed to remind the construction workers to close the protection door in time to avoid potential safety hazards.
[0026] The switch assembly 4 includes a first fixing plate 41 and a second fixing plate 42. The first fixing plate 41 is fixedly connected to the first protective door panel 2, and the second fixing plate 42 is fixedly connected to the second protective door panel 3. The first fixing plate 41 and the second fixing plate 42 are arranged opposite to each other. A limiting ring 43 is fixedly installed on the first fixing plate 41, and a plug rod 44 is installed in the limiting ring 43. A lever 45 is fixedly connected to the middle of the plug rod 44. A sleeve rod 46 is fixedly connected to the middle position of the second fixing plate 42. The plug rod 44 can slide along the middle of the limiting ring 43 and be inserted into the inside of the sleeve rod 46. During operation, the first protective door panel 2 and the second protective door panel 3 are closed. Then, the plug rod 44 is pulled along the middle of the limiting ring 43 through the lever 45, so that the end of the plug rod 44 is inserted into the inside of the sleeve rod 46, and thus the first fixing plate 41 and the second fixing plate 42 can be locked together, preventing the first fixing plate 41 and the second fixing plate 42 from being opened, playing a protective role and making the use safer.
[0027] The monitoring assembly 5 includes a fixing block 56. The fixing block 56 is fixedly connected to the inside of the end of the sleeve rod 46 far from the plug rod 44. A through hole 59 is opened in the middle of the fixing block 56. A connecting rod 57 is slidably installed inside the through hole 59. A push plate 54 is fixedly connected to the end of the connecting rod 57 close to the plug rod 44. The other end of the connecting rod 57 is fixedly connected to a pressing block 58. A first spring 55 is fixedly installed between the fixing block 56 and the push plate 54. A touch switch 510 is fixedly installed at the innermost side of the end of the sleeve rod 46 far from the plug rod 44. A controller 51, a warning lamp 52 and an alarm 53 are fixedly installed in sequence from right to left at the position adjacent to the second fixing plate 42 on the side wall of the second protective door panel 3. The touch switch 510, the warning lamp 52 and the alarm are electrically connected to the controller 51 respectively. During operation, in the initial state, the push plate 54 is pushed by the first spring 55, so that the pressing block 58 is separated from the touch switch 510. At this time, the warning lamp 52 emits red light, and the alarm 53 continuously emits a warning sound of "beep beep beep", indicating that the switch assembly 4 is not fully closed. When the end of the plug rod 44 is inserted into the inside of the sleeve rod 46 and contacts the push plate 54, and at the same time pushes the push plate 54 to continue moving towards the inside of the sleeve rod 46, then the pressing block 58 is driven to move through the connecting rod 57, so that the pressing block 58 presses the touch switch 510. The touch switch 510 is activated and then sends a signal to the controller 51. The controller 51 controls the warning lamp 52 to switch to green light, and the alarm no longer emits a warning sound, indicating that the switch has been closed in place.
[0028] There are two limiting rings 43, which are respectively fixedly connected to the transverse two ends of the first fixing plate 41. The lever 45 is arranged at the middle position between the two limiting rings 43. During operation, by arranging two limiting rings 43, the position of the plug rod 44 is restricted, so that the plug rod 44 is directly opposite to the port of the sleeve rod 46, and the movement range of the plug rod 44 can be restricted to prevent the plug rod 44 from falling off.
[0029] A limiting component 6 is arranged on the first fixing plate 41. The positions of the insertion rod 44 and the lever 45 are limited by the limiting component 6. The limiting component 6 includes two oppositely arranged U-shaped blocks 61 which are fixedly connected to the first fixing plate 41. Limiting blocks 62 are symmetrically arranged in the middle of the two U-shaped blocks 61. Through slots 63 penetrating through are respectively formed in the middle of the two side limiting blocks 62. A rotating shaft 67 is movably installed in the middle of the through slot 63. The two ends of the rotating shaft 67 are respectively rotatably installed in mounting holes 66 formed in the two side edges of the U-shaped block 61. A second spring 64 is fixedly installed on the inner wall of the through slot 63. The end of the second spring 64 abuts against the side wall of the rotating shaft 67. Symmetrically fixed connections are respectively arranged at the upper and lower ends in the middle position of the rotating shaft 67 with sliders 68. Through slots 69 are respectively formed in the middle positions of the upper and lower inner walls of the through slot 63. The sliders 68 are slidably arranged in the through slots 69. During operation, when the insertion rod 44 is inserted into the sleeve rod 46 and triggers the touch switch 510, at this time, the lever 45 is facing the middle position between the two side limiting blocks 62. Then, the lever 45 is rotated downward. The lever 45 contacts the inclined surfaces of the two side limiting blocks 62, pressing the two side limiting blocks 62 to move toward the two sides. The second spring 64 is compressed. When the lever 45 completely passes the limiting block 62, the limiting block 62 is driven by the second spring 64 to reset, thereby preventing the lever 45 from moving back. The position of the lever 45 is limited, and further, the insertion rod 44 is limited inside the sleeve rod 46, avoiding accidental detachment of the insertion rod 44 from the sleeve rod 46, and the locking is more stable. In addition, by rotating the lever 45 upward, the lever 45 pushes the two side limiting blocks 62 to flip outward around the center of the rotating shaft 67. At the same time, the sliders 68 abut against the side walls of the through slots 69, so that the rotating shaft 67 can be driven to rotate together by the limiting block 62, and the torsion spring 65 starts to store energy. Then, the lever 45 can be taken out, so that the limitation on the lever 45 and the insertion rod 44 can be removed, and thus the insertion rod 44 can be pulled out of the sleeve rod 46, and the switch component 4 can be opened.
[0030] The two ends of the rotating shaft 67 extend outward to the outside of the two ends of the U-shaped block 61, and torsion springs 65 are respectively fixedly installed at the two ends of the rotating shaft 67. During operation, the rotating shaft 67 can be reset by arranging the torsion spring 65.
[0031] The top of the opposite side edges of the two side limiting blocks 62 is set to be inclined. During operation, the lever 45 contacts the inclined surfaces of the two side limiting blocks 62, pressing the two side limiting blocks 62 to move toward the two sides.
[0032] Embodiment 2
[0033] Please refer to Figure 4As shown in the figure, compared with the first comparative embodiment, as another implementation manner of the present utility model, a retaining rod is symmetrically and fixedly connected to the opposite side walls of the two U-shaped blocks 61, and the retaining rod abuts against the bottom of the limiting block 62; during operation, the rotation direction of the limiting block 62 is restricted by arranging the retaining rod, and the limiting block 62 is kept in a position perpendicular to the U-shaped block 61.
[0034] Working principle: In the initial state, the push plate 54 is pushed by the first spring 55 to move, so that the pressing block 58 is separated from the touch switch 510. At this time, the warning light 52 emits red light, and the alarm 53 continuously emits a warning sound of "beep beep beep", indicating that the switch assembly 4 is not fully closed. Then the first protective door panel 2 and the second protective door panel 3 are closed. After that, the insertion rod 44 is pulled by the lever 45 to move along the middle of the limiting ring 43, so that the end of the insertion rod 44 is inserted into the sleeve rod 46, and then the first fixing plate 41 and the second fixing plate 42 can be locked together, preventing the first fixing plate 41 and the second fixing plate 42 from being opened, playing a protective role and being safer to use. When the end of the insertion rod 44 is inserted into the sleeve rod 46 and contacts the push plate 54, the push plate 54 is simultaneously pushed to continue moving into the sleeve rod 46. Then, the pressing block 58 is driven to move through the connecting rod 57, so that the pressing block 58 presses the touch switch 510, and the touch switch 510 is activated and then sends a signal to the controller 51. The controller 51 controls the warning light 52 to switch to green light, and the alarm no longer emits a warning sound, indicating that the switch has been closed in place.
[0035] In addition, when the insertion rod 44 is inserted into the sleeve rod 46 and triggers the touch switch 510, at this time, the lever 45 is exactly opposite the middle position between the two limiting blocks 62. Then, the lever 45 is rotated downward, and the lever 45 contacts the inclined surfaces of the two limiting blocks 62, pressing the two limiting blocks 62 to move to both sides, and the second spring 64 is compressed. When the lever 45 completely passes the limiting block 62, the limiting block 62 is driven to reset by the second spring 64, thereby preventing the lever 45 from moving back. The position of the lever 45 is restricted, and then the insertion rod 44 is restricted inside the sleeve rod 46, avoiding the accidental detachment of the insertion rod 44 from the sleeve rod 46, and the locking is more stable. In addition, by rotating the lever 45 upward, the lever 45 pushes the two limiting blocks 62 to flip outward around the center of the rotating shaft 67, and at the same time, the slider 68 abuts against the side wall of the sliding groove 69. Then, the rotating shaft 67 can be driven to rotate together by the limiting block 62, and the torsion spring 65 starts to store energy. After that, the lever 45 can be taken out, so that the restriction on the lever 45 and the insertion rod 44 can be removed, and then the insertion rod 44 can be pulled out of the sleeve rod 46, and the switch assembly 4 can be opened.
[0036] In the description of this specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.
[0037] The above has shown and described the basic principles, main features and advantages of the present utility model. Those skilled in the art should understand that the present utility model is not limited by the above embodiments, and what is described in the above embodiments and the specification is only to illustrate the principles of the present utility model. Without departing from the spirit and scope of the present utility model, the present utility model will have various changes and improvements, and these changes and improvements all fall within the scope of the present utility model claimed.
Claims
1. An intelligent monitoring device for floor safety protection doors of a construction elevator, characterized in that: The invention comprises a door frame (1), wherein a protective door panel 1 (2) and a protective door panel 2 (3) are respectively hinged on both sides of the door frame (1), a switch assembly (4) is installed on the protective door panel 1 (2) and the protective door panel 2 (3), and the protective door panel 1 (2) and the protective door panel 2 (3) are opened or closed by the switch assembly (4), and a monitoring assembly (5) is arranged on the side of the switch assembly (4), and the monitoring assembly (5) is used to monitor whether the switch assembly (4) is completely closed.
2. The intelligent monitoring device for floor safety protection doors of a construction elevator according to claim 1 is characterized in that: The switch assembly (4) comprises a fixing plate 1 (41) and a fixing plate 2 (42); the fixing plate 1 (41) is fixedly connected to the protective door plate 1 (2); the fixing plate 2 (42) is fixedly connected to the protective door plate 2 (3); the fixing plate 1 (41) and the fixing plate 2 (42) are arranged opposite to each other; a limit ring (43) is fixedly installed on the fixing plate 1 (41); an insertion rod (44) is installed in the limit ring (43); a shifting rod (45) is fixedly connected to the middle of the insertion rod (44); a sleeve rod (46) is fixedly connected to the middle of the fixing plate 2 (42); the insertion rod (44) can slide along the middle of the limit ring (43) and be inserted into the sleeve rod.
3. The intelligent monitoring device for floor safety protection doors of a construction elevator according to claim 2 is characterized in that: The monitoring assembly (5) comprises a fixed block (56), wherein the fixed block (56) is fixedly connected to the inside of the end of the sleeve rod away from the insertion rod (44), a through hole (59) is opened in the middle of the fixed block (56), a connecting rod (57) is slidably installed in the through hole (59), a push plate (54) is fixedly connected to the end of the connecting rod (57) close to the insertion rod (44), and a pressure block (58) is fixedly connected to the other end of the connecting rod (57), and the fixed block (56) is provided with a plurality of push plates (54) and a plurality of push plates (54) are provided on the connecting rod (57). A spring (55) is fixedly installed between the first and second protective door panels (56) and the push plate (54); a touch switch (510) is fixedly installed at the innermost side of the end of the sleeve rod (46) away from the insertion rod (44); a controller (51), a warning light (52) and an alarm (53) are fixedly installed in sequence from right to left at the side wall of the protective door panel (3) adjacent to the second fixed plate (42); and the touch switch (510), the warning light (52) and the alarm are electrically connected to the controller (51) respectively.
4. The intelligent monitoring device for floor safety protection doors of a construction elevator according to claim 3 is characterized in that: Two limiting rings (43) are provided and are respectively fixedly connected to the two lateral ends of the fixing plate (41), and the shifting rod (45) is arranged at the middle position of the limiting rings (43) on both sides.
5. The intelligent monitoring device for floor safety protection doors of a construction elevator according to claim 4 is characterized in that: A limit assembly (6) is provided on the fixed plate (41), and the positions of the insertion rod (44) and the shifting rod (45) are limited by the limit assembly (6). The limit assembly (6) comprises two U-shaped blocks (61) arranged opposite to each other, and the U-shaped blocks (61) are fixedly connected to the fixed plate (41). A limit block (62) is symmetrically provided in the middle of the two U-shaped blocks (61). A through long groove (63) is respectively provided in the middle of the limit blocks (62) on both sides, and a rotating shaft (63) is movably installed in the middle of the long groove (63). 7), the two ends of the rotating shaft (67) are rotatably mounted in the mounting holes (66) opened on the two side edges of the U-shaped block (61), a second spring (64) is fixedly mounted on the inner wall of the long slot (63), the end of the second spring (64) abuts against the side wall of the rotating shaft (67), a slider (68) is symmetrically fixedly connected at the upper and lower ends of the middle position of the rotating shaft (67), and a slide groove (69) is respectively opened at the middle position of the inner walls on the upper and lower sides of the long slot (63), and the slider (68) is slidably set in the slide groove (69).
6. The intelligent monitoring device for floor safety protection doors of a construction elevator according to claim 5 is characterized in that: Both ends of the rotating shaft (67) extend outward to the outside of both ends of the U-shaped block (61), and torsion springs (65) are respectively fixedly mounted on both ends of the rotating shaft (67).
7. The intelligent monitoring device for floor safety protection doors of a construction elevator according to claim 6 is characterized in that: The tops of the opposite side edges of the limiting blocks (62) on both sides are arranged to be inclined.
8. The intelligent monitoring device for floor safety protection doors of a construction elevator according to claim 7 is characterized in that: Baffle bars are symmetrically fixedly connected to the opposite side walls of the U-shaped blocks (61) on both sides, and the baffle bars abut against the bottom of the limiting blocks (62).