Device for controlling elevation of CFG pile top

Abstract

The utility model relates to the technical field of CFG pile construction, and provides a device for controlling the top elevation of a CFG pile, which comprises an I-shaped plate and a square strip arranged above the I-shaped plate, and further comprises an inserting rod movably embedded in the center of the square strip, a screw rod is embedded in the top of the square strip far away from the inserting rod in a threaded mode, and the inserting rod is connected with the inserting rod in a threaded mode. A guide rod is movably embedded in the top, away from the inserting rod, of the square strip. When pile materials are filled into the CFG pile and reach a certain height, a second connecting plate and a second fixing plate are subjected to buoyancy, a second compression spring is compressed, the second fixing plate moves upwards and touches a first pressure sensor, the first pressure sensor transmits signals to a controller, then the controller controls an alarm to sound, and the CFG pile is warned out. And a worker is reminded to stop filling of the pile material in time, so that the worker does not need to observe all the time, the situation of excessive filling of the pile material caused by distraction of the detector is avoided, and thus waste of the pile material is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of CFG pile construction, in particular to a device for controlling the elevation of the CFG pile top. Background Art

[0002] The elevation of the CFG pile top refers to the position height of the top of the CFG pile (Cement Fly-ash Gravel pile), usually referring to the distance from the ground to the top of the CFG pile. In engineering practice, this height is usually the height relative to the designed ground elevation or a certain reference plane. The CFG pile is a commonly used method in the composite foundation reinforcement technology. By driving a pile body formed by a mixture composed of materials such as cement, fly ash, and gravel into the soft foundation, the bearing capacity and stability of the foundation can be improved. Determining the elevation of the CFG pile top is crucial for ensuring that the pile body can effectively bear the load of the upper structure.

[0003] In the prior art, for example, Chinese Patent No.: CN206800406U is a CFG pile concrete surface elevation detection device, belonging to the field of CFG pile construction, including a probe rod, a collection cylinder, and a probe head. One end of the probe rod is provided with a threaded joint, and the other end of the probe rod is connected to the inner cylinder through a thread. The inner cylinder and the outer cylinder are movably connected through a positioning pin. The collection cylinder and the probe head are connected by a thread; the inner cylinder is a hollow cylinder with both ends closed. The top cover of the inner cylinder is provided with a threaded hole, and a positioning pin is welded to the outer wall of the inner cylinder; the outer cylinder is sleeved around the inner cylinder and there is a gap between the outer cylinder and the inner cylinder. The cylinder wall of the outer cylinder is provided with an L-shaped positioning groove, and a spring is wound around the cylinder wall of the outer cylinder; the outer cylinder is welded to the collection cylinder. One end of the collection cylinder is welded to the outer cylinder, and the other end of the collection cylinder is connected to the probe head through a thread; a rotary window is provided on the cylinder wall of the collection cylinder. The utility model is light in weight, simple in structure, convenient to operate, accurate in measurement, can be widely applied in the field of CFG pile construction, reduce the waste of pile body concrete, and ensure the construction quality of CFG piles.

[0004] Although the above solution has the above advantages, the disadvantages of the above solution are as follows: Although it is light in weight, simple in structure, convenient to operate, accurate in measurement, can be widely applied in the construction field of CFG piles, reduce the waste of pile body concrete, and ensure the construction quality of CFG piles, when the device measures the elevation of the CFG pile top, it requires the inspectors to observe continuously. When the inspectors are distracted, they may not be able to observe the height of the pile material filling in time, resulting in the inability to stop the pile material filling in time, which may lead to the situation of excessive pile material filling, and further lead to the waste of pile material. Summary of the Utility Model

[0005] The purpose of the present utility model is to solve the problem existing in the prior art that although it has the advantages of light weight, simple structure, convenient operation, accurate measurement, and can be widely applied to the construction field of CFG piles, reducing the waste of pile body concrete and ensuring the construction quality of CFG piles. However, when the device measures the elevation of the CFG pile top, it requires the inspectors to keep observing all the time. When the inspectors are distracted, it may be impossible to observe the height of the pile material filling in time, resulting in the inability to stop the filling of the pile material in time, which may lead to the situation of excessive filling of the pile material and further cause waste of the pile material.

[0006] To achieve the above purpose, the present utility model adopts the following technical scheme: A device for controlling the elevation of the CFG pile top, comprising: an I-shaped plate and a square bar, the square bar is arranged above the I-shaped plate, and further comprising:

[0007] A plug rod is movably embedded in the center of the square bar. A screw rod is threadedly embedded at the top of the square bar away from the plug rod. A guide rod is movably embedded at the top of the square bar away from the plug rod. One end of the screw rod is movably sleeved with a first connecting plate. The top of the first connecting plate is fixedly installed at one end of the guide rod. Two telescopic rods are symmetrically and fixedly installed at the bottom of the first connecting plate. One end of each of the two telescopic rods is fixedly installed with a second connecting plate. Two compression springs II are movably sleeved on the outer surfaces of the two telescopic rods. One end of each of the two compression springs II is symmetrically and fixedly installed at the bottom of the first connecting plate. The other end of each of the two compression springs II is symmetrically and fixedly installed at the top of the second connecting plate. One side of the first connecting plate is fixedly installed with a first fixing plate. A first pressure sensor is fixedly installed at the bottom of the first fixing plate away from the first connecting plate. One side of the second connecting plate is fixedly installed with a second fixing plate. An alarm is fixedly installed at one end of the plug rod.

[0008] Preferably, a ring is fixedly installed at the center of the bottom of the square bar. The inner wall of the ring is movably sleeved on the outer surface of the plug rod. A plurality of elastic pieces are fixedly installed at the bottom of the ring in a circumferential array. A knob is threadedly sleeved on the outer surface of the ring. By turning the knob with the hand, it moves downward along the outer surface of the ring, applying a squeezing force to the elastic pieces, causing the elastic pieces to move closer to the middle and squeezing the plug rod to fix the plug rod.

[0009] Preferably, a chute is opened at the bottom of the plug rod. A movable rod is movably embedded in the chute. A second pressure sensor is fixedly installed at the top of the inner wall of the chute. Through the above setting, when the movable rod slides into the chute and touches the second pressure sensor, the signal can be transmitted to the controller through the second pressure sensor.

[0010] Preferably, a third compression spring is movably embedded inside the sliding groove. One end of the third compression spring is fixedly installed at the top of the inner wall of the sliding groove, and the other end of the third compression spring is fixedly installed at the top of the movable rod. Through the arrangement of the third compression spring, when the acting force on the movable rod disappears, under the restoring force of the third compression spring, the movable rod can be reset.

[0011] Preferably, the center of the first connecting plate is movably sleeved on the outer surface of the insertion rod, the center of the second connecting plate is movably sleeved on the outer surface of the insertion rod, scale lines are arranged on the outer surface of the insertion rod, and a turning handle is fixedly installed at one end of the screw rod. Through the above arrangement, it is convenient for the insertion rod to slide up and down, and through the arrangement of the scale lines, it is convenient to observe.

[0012] Preferably, two vertical plates are symmetrically and fixedly installed at the top of the I-shaped plate. A rotating rod is movably embedded on the opposite sides of the two vertical plates close to the top. Two connecting strips are symmetrically and fixedly sleeved on the outer surface of the rotating rod. Connecting rods are fixedly installed on the opposite sides of the two connecting strips away from the rotating rod. One ends of the two connecting rods are respectively fixedly installed on the opposite sides of the square bar. Universal self-locking wheels are fixedly installed at the four corners of the bottom of the I-shaped plate. By rotating the rotating rod, the connecting strips, the connecting rods and the square bar can be driven to rotate.

[0013] Preferably, a limiting hole is opened on one side of the vertical plate close to the rotating rod. An L-shaped block is fixedly sleeved at one end of the rotating rod. Two limiting rods are movably embedded on one side of the L-shaped block. One end of one of the limiting rods is movably embedded inside the limiting hole. By inserting the limiting rod into the limiting hole, the L-shaped block is limited.

[0014] Preferably, compression springs are movably sleeved on the outer surfaces of the two limiting rods. One ends of the two compression springs are fixedly installed on one side of the L-shaped block, and the other ends of the two compression springs are respectively fixedly installed at one ends of the two limiting rods. Under the restoring force of the compression springs, the limiting rods can be inserted into the limiting holes.

[0015] Compared with the prior art, the advantages and positive effects of the present utility model are as follows:

[0016] 1. In the present utility model, when filling the CFG pile with pile material, when it reaches a certain height, a buoyancy force will act on the second connecting plate and the second fixing plate, causing the telescopic rod to contract and compressing the second compression spring. When the second fixing plate moves upward, it will touch the first pressure sensor, and the first pressure sensor will transmit a signal to the controller, and then the controller controls the alarm to sound, timely reminding the staff to stop filling the pile material. In this way, there is no need for the staff to observe all the time, avoiding distraction of the detection personnel and resulting in excessive filling of the pile material, thus avoiding waste of the pile material.

[0017] 2. In the present utility model, by pulling the limiting rod to one side by hand to disengage it from the inside of the limiting hole, the limitation on the L-shaped block is released, and simultaneously the first compression spring is stretched. At this time, the L-shaped block can be rotated downward by 90 degrees, driving the rotating rod, connecting strip, connecting rod, square bar, etc. to rotate downward by 90 degrees. Then, another limiting rod is inserted into the inside of the limiting hole under the restoring force of another first compression spring to realize the limitation on the L-shaped block. In this way, the square bar can be moved to a position close to the top of the I-shaped plate, thus facilitating the storage of this device and reducing the space occupation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 FIG. 7 is a schematic bottom view structure diagram of a device for controlling the top elevation of CFG piles provided by the present utility model;

[0019] Figure 2 A device for controlling the top elevation of CFG piles provided by the present utility model Figure 1 is an enlarged structure diagram at A in FIG.

[0020] Figure 3 A device for controlling the top elevation of CFG piles provided by the present utility model Figure 1 is an enlarged structure diagram at B in FIG.

[0021] Figure 4 is a schematic cross-sectional structure diagram of the insertion rod of a device for controlling the top elevation of CFG piles provided by the present utility model.

[0022] LEGEND DESCRIPTION:

[0023] 1. I-shaped plate; 101. Vertical plate; 102. Rotating rod; 103. Connecting strip; 104. Connecting rod; 105. L-shaped block; 106. Limiting rod; 107. First compression spring; 108. Limiting hole; 2. Square bar; 201. Insertion rod; 202. Guide rod; 203. Screw rod; 204. Rotating handle; 205. Ring; 206. Knob; 207. Elastic sheet; 208. First connecting plate; 209. Telescopic rod; 210. Second compression spring; 211. Second connecting plate; 212. First fixing plate; 213. First pressure sensor; 214. Second fixing plate; 215. Movable rod; 216. Chute; 217. Second pressure sensor; 218. Third compression spring. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] In order to more clearly understand the above-mentioned objects, features, and advantages of the present utility model, the following further describes the present utility model with reference to the drawings and embodiments. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0025] In the following description, many specific details are set forth in order to provide a thorough understanding of the present utility model. However, the present utility model may also be implemented in other ways different from those described herein. Therefore, the present utility model is not limited by the specific embodiments disclosed in the following specification.

[0026] Embodiment 1, as Figures 1 to 4 shown, the present utility model provides a device for controlling the elevation of the CFG pile top, including: an I-shaped plate 1 and a square bar 2. The square bar 2 is arranged above the I-shaped plate 1. It further includes: a plug rod 201, movably embedded in the center of the square bar 2. At the top of the square bar 2 away from the plug rod 201, a screw rod 203 is threadedly embedded. At the top of the square bar 2 away from the plug rod 201, a guide rod 202 is movably embedded. One end of the screw rod 203 is movably sleeved with a first connecting plate 208. The top of the first connecting plate 208 is fixedly installed at one end of the guide rod 202. At the bottom of the first connecting plate 208, two telescopic rods 209 are symmetrically and fixedly installed. At one end of the two telescopic rods 209, a second connecting plate 211 is fixedly installed. On the outer surfaces of the two telescopic rods 209, two second compression springs 210 are movably sleeved. One end of the two second compression springs 210 is symmetrically and fixedly installed at the bottom of the first connecting plate 208. The other end of the two second compression springs 210 is symmetrically and fixedly installed at the top of the second connecting plate 211. On one side of the first connecting plate 208, a first fixing plate 212 is fixedly installed. Away from the bottom of the first connecting plate 208, a first pressure sensor 213 is fixedly installed on the first fixing plate 212. On one side of the second connecting plate 211, a second fixing plate 214 is fixedly installed. An alarm is fixedly installed at one end of the plug rod 201. At the center of the bottom of the square bar 2, a ring 205 is fixedly installed. The inner wall of the ring 205 is movably sleeved on the outer surface of the plug rod 201. At the bottom of the ring 205, a plurality of elastic pieces 207 are fixedly installed in a circumferential array. A knob 206 is threadedly sleeved on the outer surface of the ring 205. At the bottom of the plug rod 201, a chute 216 is opened. Inside the chute 216, a movable rod 215 is movably embedded. At the top of the inner wall of the chute 216, a second pressure sensor 217 is fixedly installed. Inside the chute 216, a third compression spring 218 is movably embedded. One end of the third compression spring 218 is fixedly installed at the top of the inner wall of the chute 216. The other end of the third compression spring 218 is fixedly installed at the top of the movable rod 215. The center of the first connecting plate 208 is movably sleeved on the outer surface of the plug rod 201. The center of the second connecting plate 211 is movably sleeved on the outer surface of the plug rod 201. Scale lines are arranged on the outer surface of the plug rod 201. A turning handle 204 is fixedly installed at one end of the screw rod 203.

[0027] In this embodiment, by inserting the insertion rod 201 downward into the pile pit, when the movable rod 215 touches the bottom of the pile pit, it will receive a force, causing the movable rod 215 to move toward the inside of the chute 216, simultaneously compressing the third compression spring 218. When the movable rod 215 touches the second pressure sensor 217, the signal can be transmitted to the controller through the second pressure sensor 217, and then the controller controls the alarm to sound, indicating that the insertion rod 201 has been inserted to the bottom of the pile pit. Then, by manually rotating the knob 206, it moves downward along the outer surface of the ring 205, applying a squeezing force to the elastic piece 207, causing the elastic piece 207 to move closer to the middle, squeezing the insertion rod 201 to fix it. Then, by manually rotating the handle 204, it drives the screw rod 203 to rotate. Under the action of the threaded fit between the screw rod 203 and the square bar 2, and with the cooperation of the guide rod 202 limiting and guiding the first connecting plate 208, the screw rod 203 can drive the first connecting plate 208 to move downward, causing the guide rod 202 to slide downward, so that the first pressure sensor 213 coincides with a scale line at a certain position on the insertion rod 201, that is, the CFG pile top elevation position. When the pile material is filled into the CFG pile, when it reaches a certain height, the second connecting plate 211 and the second fixing plate 214 will receive a buoyancy force, causing the telescopic rod 209 to contract and compressing the second compression spring 210. By moving upward through the second fixing plate 214, it will touch the first pressure sensor 213, causing the first pressure sensor 213 to transmit a signal to the controller, and then the controller controls the alarm to sound, timely reminding the staff to stop filling the pile material. In this way, there is no need for the staff to observe all the time, avoiding the distraction of the detection personnel and resulting in the situation of excessive filling of the pile material, thus avoiding waste of the pile material.

[0028] Embodiment 2, as Figures 1 to 4 shown, two vertical plates 101 are symmetrically and fixedly installed at the top of the I-shaped plate 1. Two rotating rods 102 are movably embedded on the opposite sides of the two vertical plates 101 close to the top. Two connecting strips 103 are symmetrically and fixedly sleeved on the outer surface of the rotating rod 102. One ends of the two connecting strips 103 away from the rotating rod 102 are fixedly installed with connecting rods 104 respectively. One ends of the two connecting rods 104 are fixedly installed on the opposite sides of the square bar 2 respectively. Universal self-locking wheels are fixedly installed at the four corners of the bottom of the I-shaped plate 1. A limiting hole 108 is opened on one side of one of the vertical plates 101 close to the rotating rod 102. An L-shaped block 105 is fixedly sleeved at one end of the rotating rod 102. Two limiting rods 106 are movably embedded on one side of the L-shaped block 105. One end of one of the limiting rods 106 is movably embedded in the internal of the limiting hole 108. Compression springs 107 are movably sleeved on the outer surfaces of the two limiting rods 106. One ends of the two compression springs 107 are fixedly installed on one side of the L-shaped block 105, and the other ends of the two compression springs 107 are fixedly installed at one ends of the two limiting rods 106 respectively.

[0029] In this embodiment, by pulling the limiting rod 106 to one side by hand, it is disengaged from the inside of the limiting hole 108 to release the limitation on the L-shaped block 105, and at the same time, the first compression spring 107 is stretched. At this time, the L-shaped block 105 can be rotated downward by 90 degrees, driving the rotating rod 102, the connecting strip 103, the connecting rod 104, the square bar 2, etc. to rotate downward by 90 degrees. Then, another limiting rod 106 is inserted into the inside of the limiting hole 108 under the reset force of another first compression spring 107 to realize the limitation on the L-shaped block 105. In this way, the square bar 2 can be moved to a position close to the top of the I-shaped plate 1, thus facilitating the storage of this device and reducing the space occupation.

[0030] Working principle: When in use, the insertion rod 201 is inserted downward into the pile pit. When the movable rod 215 touches the bottom of the pile pit, it will receive a force, causing the movable rod 215 to move inward along the chute 216, and simultaneously compressing the third compression spring 218. When the movable rod 215 touches the second pressure sensor 217, the signal can be transmitted to the controller through the second pressure sensor 217, and then the controller controls the alarm to sound, indicating that the insertion rod 201 has been inserted to the bottom of the pile pit. Then, by turning the knob 206 by hand, it moves downward along the outer surface of the ring 205, applying a squeezing force to the elastic piece 207, causing the elastic piece 207 to move closer to the middle, squeezing the insertion rod 201 to fix the insertion rod 201. Then, by turning the handle 204 by hand, it drives the screw rod 203 to rotate. Under the action of the threaded fit between the screw rod 203 and the square bar 2, and with the cooperation of the guide rod 202 for limiting and guiding the first connecting plate 208, the screw rod 203 can drive the first connecting plate 208 to move downward, causing the guide rod 202 to slide downward, so that the first pressure sensor 213 coincides with a scale line at a certain position on the insertion rod 201, that is, the CFG pile top elevation position. When the pile material is filled into the CFG pile, when it reaches a certain height, the second connecting plate 211 and the second fixing plate 214 will receive a buoyancy force, causing the telescopic rod 209 to contract and compressing the second compression spring 210. By moving upward through the second fixing plate 214, it will touch the first pressure sensor 213, causing the first pressure sensor 213 to transmit a signal to the controller, and then the controller controls the alarm to sound, timely reminding the staff to stop filling the pile material. In this way, it is not necessary for the staff to observe all the time, avoiding the situation that the inspectors are distracted and the pile material is filled too much, thus avoiding waste of the pile material. When this device is not needed, by rotating the knob 206 in the reverse direction, the extrusion of the elastic piece 207 is released, and it is reset under the elastic action of the elastic piece 207, thus releasing the fixed state of the insertion rod 201. At this time, the insertion rod 201 can be pulled out upward, and then the limiting rod 106 is pulled to one side by hand, causing it to disengage from the inside of the limiting hole 108, releasing the limit on the L-shaped block 105, and simultaneously stretching the first compression spring 107. At this time, the L-shaped block 105 can be rotated downward by 90 degrees, driving the rotating rod 102, the connecting strip 103, the connecting rod 104, the square bar 2, etc. to rotate downward by 90 degrees, and then another limiting rod 106 is inserted into the inside of the limiting hole 108 under the reset action of another first compression spring 107 to realize the limit on the L-shaped block 105. In this way, the square bar 2 can be moved to a position close to the top of the I-shaped plate 1, thus facilitating the storage of this device and reducing the space occupation.

[0031] The above are only the preferred embodiments of the present utility model, and are not intended to limit the present utility model in other forms. Any person skilled in the art may use the technical content disclosed above to make changes or modifications into equivalent embodiments with equivalent changes and apply them to other fields. However, as long as it does not depart from the technical solution content of the present utility model, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present utility model still fall within the protection scope of the technical solution of the present utility model.

Claims

1. A device for controlling the elevation of a CFG pile top, comprising: An I-shaped plate (1) and a square bar (2), wherein the square bar (2) is arranged above the I-shaped plate (1), and is characterized in that it further comprises: The plug rod (201) is movably embedded in the center of the square bar (2); a screw rod (203) is threadedly embedded in the top of the square bar (2) away from the plug rod (201); a guide rod (202) is movably embedded in the top of the square bar (2) away from the plug rod (201); one end of the screw rod (203) is movably sleeved with a connecting plate (208); the top of the connecting plate (208) is fixedly mounted on one end of the guide rod (202); two telescopic rods (209) are symmetrically fixedly mounted on the bottom of the connecting plate (208); one end of the two telescopic rods (209) is fixedly mounted with a connecting plate (211); the two telescopic rods (209) are ) is provided with two compression springs 2 (210) on the outer surface of the movable sleeve, one end of the two compression springs 2 (210) is symmetrically fixedly installed on the bottom of the connecting plate 1 (208), and the other end of the two compression springs 2 (210) is symmetrically fixedly installed on the top of the connecting plate 2 (211), one side of the connecting plate 1 (208) is fixedly installed with a fixing plate 1 (212), and a pressure sensor 1 (213) is fixedly installed on the fixing plate 1 (212) away from the bottom of the connecting plate 1 (208), and one side of the connecting plate 2 (211) is fixedly installed with a fixing plate 2 (214), and one end of the plug rod (201) is fixedly installed with an alarm.

2. A device for controlling the elevation of a CFG pile top according to claim 1, characterized in that: A circular ring (205) is fixedly mounted at the center of the bottom of the square bar (2); the inner wall of the circular ring (205) is movably sleeved on the outer surface of the insertion rod (201); a plurality of spring pieces (207) are fixedly mounted in a circular array on the bottom of the circular ring (205); and a knob (206) is threadedly sleeved on the outer surface of the circular ring (205).

3. A device for controlling the elevation of a CFG pile top according to claim 2, characterized in that: A slide groove (216) is provided at the bottom of the insertion rod (201), a movable rod (215) is movably embedded inside the slide groove (216), and a second pressure sensor (217) is fixedly mounted on the top of the inner wall of the slide groove (216).

4. A device for controlling the elevation of a CFG pile top according to claim 3, characterized in that: A compression spring three (218) is movably embedded inside the slide groove (216), one end of the compression spring three (218) is fixedly mounted on the top of the inner wall of the slide groove (216), and the other end of the compression spring three (218) is fixedly mounted on the top of the movable rod (215).

5. A device for controlling the elevation of a CFG pile top according to claim 3, characterized in that: The center of the connecting plate 1 (208) is movably sleeved on the outer surface of the insertion rod (201), and the center of the connecting plate 2 (211) is movably sleeved on the outer surface of the insertion rod (201). The outer surface of the insertion rod (201) is provided with scale lines, and a turning handle (204) is fixedly mounted on one end of the screw rod (203).

6. A device for controlling the elevation of a CFG pile top according to claim 2, characterized in that: Two vertical plates (101) are symmetrically fixedly mounted on the top of the I-shaped plate (1); rotating rods (102) are movably embedded on opposite sides of the two vertical plates (101) close to the top; two connecting bars (103) are symmetrically fixedly sleeved on the outer surface of the rotating rod (102); connecting rods (104) are fixedly mounted on opposite sides of the two connecting bars (103) away from the rotating rod (102); one end of the two connecting rods (104) is respectively fixedly mounted on opposite sides of the square bar (2); and universal self-locking wheels are fixedly mounted at the four corners of the bottom of the I-shaped plate (1).

7. A device for controlling the elevation of a CFG pile top according to claim 6, characterized in that: A limiting hole (108) is provided on one side of one of the vertical plates (101) close to the rotating rod (102); an L-shaped block (105) is fixedly sleeved on one end of the rotating rod (102); two limiting rods (106) are movably embedded on one side of the L-shaped block (105); one end of one of the limiting rods (106) is movably embedded in the limiting hole (108).

8. A device for controlling the elevation of a CFG pile top according to claim 7, characterized in that: The outer surfaces of the two limit rods (106) are movably sleeved with compression springs (107), one end of the two compression springs (107) is fixedly mounted on one side of the L-shaped block (105), and the other ends of the two compression springs (107) are respectively fixedly mounted on one end of the two limit rods (106).

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