A precast concrete pipe pile conveying device

Abstract

The application discloses a prefabricated concrete pipe pile conveying equipment and relates to the technical field of prefabricated concrete pipe pile conveying, which comprises a vehicle frame, a pushing frame is fixedly installed on the upper surface right side of the vehicle frame, a balance mechanism for converting braking force into meshing force is arranged and installed on the lower surface of the vehicle frame, and a buffer mechanism for converting braking force into buffer force is arranged and installed on the lower surface of the vehicle frame. The buffer mechanism avoids damage to overall braking by buffering. The balance mechanism comprises a fixing frame, a rotating shaft, a moving wheel, a gear, a ratchet, a bearing block, a ratchet wheel, an L-shaped plate, a connecting shaft and a fixed rack. When emergency braking or downhill driving is performed, the vehicle frame slides forward relative to the moving wheel, drives the fixed rack to rotate the gear, and then makes the ratchet and the ratchet wheel one-way lock, converts linear inertial impact of the pipe pile body into meshing force and transmits the meshing force to the ground, effectively prevents further forward sliding of the vehicle frame, and prevents the pipe pile body from violently impacting the front limiting block and being thrown out from the front.

Description

Technical Field

[0001] This invention relates to the field of precast concrete pipe pile transportation technology, specifically to a precast concrete pipe pile transportation device. Background Technology

[0002] Precast concrete pipe piles are high-strength precast concrete components widely used in construction, bridges, ports and other engineering fields. They are usually made using prestressed pretensioning and centrifugal molding technology. They have advantages such as high load-bearing capacity, good durability and fast construction speed. They are driven into the foundation by hammering or static pressure to bear the load of the superstructure. During the transportation of precast concrete pipe piles, flatbed trailers, beam transport vehicles or cranes are usually used for transfer within the factory or at the construction site.

[0003] In the existing technology, the transportation of precast concrete pipe piles first involves using a crane or hoisting equipment to lift the pipe piles from the storage yard or curing area and place them horizontally on a flatbed trailer. Then, the truck is moved to the target location. Upon arrival, the rigging is removed, and the pipe piles are unloaded and stacked or directly sent into the guide frame of the pile driver using hoisting equipment.

[0004] However, when the flatbed truck suddenly decelerates during operation, the pipe piles will slide forward and collide with the front limit block. Due to the increased center of gravity, the entire trailer will tip forward using the front wheels as a fulcrum. Conventional limit blocks can only stop the pipe piles from sliding, but cannot prevent the entire vehicle from tilting upwards due to inertial torque. The pipe piles will be thrown out from the front, injuring operators or surrounding facilities. At the same time, the rear of the pipe piles will also sweep across the surrounding area due to tilting, causing secondary injuries. The entire transportation process therefore poses a significant safety hazard and reduces the safety of actual operation.

[0005] While it can solve the above problems, it cannot provide a certain buffer during operation. Therefore, when braking suddenly or going downhill, the inertial impact force of the pipe pile will cause an instantaneous peak load, which can easily lead to the cracking of the pipe pile end plate and the collapse of the pile head concrete, and also bring certain dangers. Summary of the Invention

[0006] The purpose of this invention is to provide a precast concrete pipe pile conveying device to solve the problem of improving operational safety during braking.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a precast concrete pipe pile conveying device, comprising a frame, a pusher fixedly installed on the right side of the upper surface of the frame, a balancing mechanism for converting braking force into meshing force installed on the lower surface of the frame, and a buffer mechanism for converting braking force into buffering force installed on the lower surface of the frame, wherein the buffer mechanism avoids damage to the overall braking by buffering.

[0008] Preferably, the balancing mechanism includes a fixed frame, a rotating shaft, a movable wheel, a gear, a ratchet, and a receiving block. The upper outer surface of the fixed frame is slidably connected to the inner wall of the bottom of the frame. The outer surface of the rotating shaft is rotatably mounted to the inner wall of the fixed frame. The interior of the movable wheel is fixedly mounted to the outer surface of the rotating shaft. The interior of the gear is fixedly mounted to the outer surface of the rotating shaft. One side of the ratchet is fixedly mounted to the outer surface of one end of the rotating shaft. The upper surface of the receiving block is fixedly mounted to the lower surface of the frame.

[0009] Preferably, the buffer mechanism includes a support spring and a guide telescopic rod, and a buffer groove is formed on the lower surface of the frame. One end of the support spring is fixedly installed inside the buffer groove, and one end of the guide telescopic rod is fixedly installed inside the buffer groove.

[0010] Preferably, a fixed rack is fixedly installed on the lower surface of the receiving block, and the fixed rack is meshed with a gear.

[0011] Preferably, an L-shaped plate is fixedly installed on one side of the receiving block, and a connecting shaft is rotatably installed on the inner wall of the L-shaped plate.

[0012] Preferably, a ratchet is fixedly mounted on the outer surface of one end of the connecting shaft, and the outer surface of the ratchet engages with the surface of the ratchet bar.

[0013] Preferably, one end of the receiving spring is fixedly installed to one side of the bottom end of the fixed frame, and one end of the guide telescopic rod is fixedly installed to one side of the bottom end of the fixed frame.

[0014] Preferably, a screw is rotatably mounted on the inner wall of the frame, a screwing block is fixedly mounted on one end of the screw, and a detachable locking block is mounted on the outer surface of the screw.

[0015] Preferably, a lower fastening ring is fitted onto the upper surface of the frame, and the inner wall of the bottom end of the lower fastening ring is threaded onto the outer surface of the screw.

[0016] Preferably, an upper fastening ring is fitted onto the upper surface of the lower fastening ring, and studs are installed on both the lower and upper fastening rings. A nut is fixedly installed at one end of the stud, and a locking screw is threaded onto the outer surface of the bottom end of the stud. The pipe pile body is installed on the inner ring of both the lower and upper fastening rings.

[0017] Compared with the prior art, the beneficial effects of the present invention are: This invention employs a balancing mechanism, including a fixed frame, a rotating shaft, a moving wheel, a gear, a ratchet, a receiving block, a ratchet wheel, an L-shaped plate, a connecting shaft, and a fixed rack. During emergency braking or downhill driving, the frame slides forward relative to the moving wheel, causing the fixed rack to drive the gear to rotate. This locks the ratchet and ratchet wheel in one direction, converting the linear inertial impact of the pipe pile into a meshing force and transmitting it to the ground. This effectively prevents further forward sliding of the frame, avoids the pipe pile from violently impacting the front limit block, and prevents it from being thrown out from the front. Simultaneously, the reverse torque suppresses the entire vehicle from tipping forward with the front wheels as the fulcrum, preventing the rear of the pipe pile from lifting up and sweeping across the surrounding area. This completely solves the problem of the entire vehicle tilting up and causing secondary damage due to inertial torque in existing technologies, and improves the operational safety of the transportation process.

[0018] This invention employs a buffer mechanism, including a buffer groove on the lower surface of the frame, and a receiving spring and a guide telescopic rod installed inside the buffer groove. One end of the receiving spring and one end of the guide telescopic rod are fixedly installed to one side of the bottom of a fixed frame. During emergency braking, the receiving spring absorbs the instantaneous peak load generated by the pipe pile body, transforming rigid impact into elastic buffering, effectively preventing structural damage such as pipe pile end plate breakage and pile head concrete collapse. The guide telescopic rod ensures linear stability during the buffering process, preventing equipment jamming due to uneven loading. Working in conjunction with the balancing mechanism, it provides overload protection for mechanical transmission components while achieving anti-rollover braking, extending the service life of key parts such as gears, racks, and ratchet, and reducing safety risks caused by severe vibrations during operation. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 For the present invention Figure 1 A top-view structural diagram; Figure 3 For the present invention Figure 1 A schematic diagram of the side view structure; Figure 4 For the present invention Figure 3 Enlarged schematic diagram of the structure at point A; Figure 5 For the present invention Figure 1 A schematic diagram of the structure viewed from below; Figure 6 For the present invention Figure 1 A schematic diagram of the cross-sectional structure; Figure 7 For the present invention Figure 6 Enlarged schematic diagram of the structure at point B; Figure 8 For the present invention Figure 6 A magnified schematic diagram of the structure at point C.

[0020] In the diagram: 1. Frame; 2. Push frame; 3. Screw; 4. Tightening block; 5. Removable locking block; 6. Lower fastening ring; 7. Upper fastening ring; 8. Stud; 9. Nut; 10. Locking screw block; 11. Pipe pile body; 12. Balancing mechanism; 121. Fixed frame; 122. Rotating shaft; 123. Moving wheel; 124. Gear; 125. Ratchet; 126. Receiving block; 127. Ratchet; 128. L-shaped plate; 129. Connecting shaft; 1210. Fixed rack; 13. Buffer mechanism; 131. Buffer groove; 132. Receiving spring; 133. Guide telescopic rod. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figure 1 , Figure 6 and Figure 7 As shown, the present invention provides a technical solution: a precast concrete pipe pile conveying device, including a frame 1, a pusher frame 2 fixedly installed on the right side of the upper surface of the frame 1, a balancing mechanism 12 for converting braking force into meshing force installed on the lower surface of the frame 1, and a buffer mechanism 13 for converting braking force into buffering force installed on the lower surface of the frame 1. The buffer mechanism 13 buffers and avoids damage to the overall braking. The balancing mechanism 12 includes a fixed frame 121, a rotating shaft 122, a moving wheel 123, a gear 124, a ratchet 125, and a receiving block 126. The upper outer surface of the fixed frame 121 is slidably connected to the inner wall of the bottom of the frame 1, and the outer surface of the rotating shaft 122 rotates with the inner wall of the fixed frame 121. The installation includes: the interior of the movable wheel 123 is fixedly installed to the outer surface of the rotating shaft 122; the interior of the gear 124 is fixedly installed to the outer surface of the rotating shaft 122; one side of the ratchet 125 is fixedly installed to the outer surface of one end of the rotating shaft 122; the upper surface of the receiving block 126 is fixedly installed to the lower surface of the frame 1; a fixed rack 1210 is fixedly installed on the lower surface of the receiving block 126; the fixed rack 1210 and the gear 124 are meshed; an L-shaped plate 128 is fixedly installed on one side of the receiving block 126; a connecting shaft 129 is rotatably installed on the inner wall of the L-shaped plate 128; a ratchet 127 is fixedly installed on the outer surface of one end of the connecting shaft 129; and the outer surface of the ratchet 127 meshes with the surface of the ratchet 125.

[0023] Specifically, by setting up a balancing mechanism 12, the braking force is converted into a meshing force. During braking, gear 124 meshes with fixed rack 1210, and ratchet 127 meshes with ratchet 125. This double meshing and ratcheting structure can more effectively transmit the braking force, causing the moving wheel 123 to stop rotating quickly. This improves the reliability and stability of braking, ensuring that the precast concrete pipe pile conveying equipment can stop quickly and smoothly during braking, avoiding safety problems such as pipe pile slippage and equipment damage caused by untimely or uneven braking. The buffer mechanism 13 converts braking force into buffer force during braking, preventing damage to the equipment from the enormous impact force generated during overall braking. This helps extend the equipment's service life, reduces component damage and wear caused by frequent braking, and lowers maintenance costs and replacement frequency. The ratchet 127 and ratchet 125 engagement structure has a unidirectional braking characteristic, enabling precise braking control of the moving wheel 123. When braking is required, the ratchet 127 and ratchet 125 quickly engage, preventing the moving wheel 123 from rotating; while during normal operation, the ratchet 127 and ratchet 125 do not interfere with each other, ensuring the normal rotation of the moving wheel 123 and improving the equipment's operational flexibility and braking accuracy.

[0024] according to Figure 1 , Figure 6 and Figure 8 As shown, the buffer mechanism 13 includes a receiving spring 132 and a guide telescopic rod 133. A buffer groove 131 is provided on the lower surface of the frame 1. One end of the receiving spring 132 is fixedly installed inside the buffer groove 131. One end of the guide telescopic rod 133 is fixedly installed inside the buffer groove 131. One end of the receiving spring 132 is fixedly installed on one side of the bottom end of the fixing frame 121. One end of the guide telescopic rod 133 is fixedly installed on one side of the bottom end of the fixing frame 121.

[0025] Specifically, the bearing spring 132 in the buffer mechanism 13 has good elastic properties. When the equipment brakes or is subjected to external impact, the bearing spring 132 can undergo elastic deformation, absorbing and dispersing most of the impact force, converting the braking force into a buffer force, effectively reducing the impact on the frame 1 and the overall equipment, preventing damage to the equipment due to excessive instantaneous force, and extending the service life of the equipment. The guide telescopic rod 133 works in conjunction with the receiving spring 132. When the receiving spring 132 deforms to buffer, the guide telescopic rod 133 can extend and retract along a predetermined direction, providing stable guidance for the movement of the fixed frame 121. This prevents the fixed frame 121 from shifting or shaking during the buffering process, ensuring the stability and reliability of the buffering mechanism 13, and thus ensuring the smooth operation of the entire conveying equipment under braking and other conditions. One end of both the receiving spring 132 and the guide telescopic rod 133 is fixed inside the buffer groove 131, and the other end is fixed to one side of the bottom of the fixed frame 121. The two work together. The receiving spring 132 provides the main buffering force, and the guide telescopic rod 133 controls the buffering direction. This combination can more comprehensively and effectively cope with impact forces of different directions and sizes, improve the overall buffering performance of the buffering mechanism 13, and better protect the equipment and pipe piles.

[0026] according to Figure 1 , Figure 2 , Figure 3 and Figure 5 As shown, a screw 3 is rotatably mounted on the inner wall of the frame 1. A screwing block 4 is fixedly mounted on one end of the screw 3. A detachable locking block 5 is mounted on the outer surface of the screw 3. A lower fastening ring 6 is fitted to the upper surface of the frame 1. The inner wall of the bottom end of the lower fastening ring 6 is threaded to the outer surface of the screw 3. An upper fastening ring 7 is fitted to the upper surface of the lower fastening ring 6. Studs 8 are mounted on the lower fastening ring 6 and the upper fastening ring 7. A nut 9 is fixedly mounted on one end of the stud 8. A locking screw block 10 is threaded on the outer surface of the bottom end of the stud 8. A pipe pile body 11 is mounted on the inner ring of the lower fastening ring 6 and the upper fastening ring 7.

[0027] Specifically, the screw 3, which is rotatably mounted on the inner wall of the frame 1, is threaded onto the screw 3 via the inner wall of the lower fastening ring 6. When the rotating screw 3 is driven to rotate by the rotating block 4, the lower fastening ring 6 can move on the screw 3, thereby engaging with the upper fastening ring 7 to tightly clamp the pipe pile body 11. This threaded fastening method provides a strong and stable clamping force, ensuring that the pipe pile body 11 will not loosen or shift during transportation, thus guaranteeing the safety and reliability of transportation. A detachable locking block 5 is installed on the outer surface of the screw rod 3. When it is necessary to install or remove the lower fastening ring 6, the detachable locking block 5 can be operated first to facilitate the relevant operations on the screw rod 3. At the same time, the lower fastening ring 6 and the upper fastening ring 7 are connected and fixed by studs 8, nuts 9 and locking bolts 10. This connection method allows for quick completion of the operation when installing and removing the pipe pile body 11 by simply tightening or loosening the nuts 9 and locking bolts 10, which improves work efficiency and facilitates equipment maintenance and pipe pile replacement. The lower fastening ring 6 and the upper fastening ring 7 are connected by multiple sets of studs 8, nuts 9 and locking bolts 10 to form a stable frame structure, which can evenly distribute the clamping force on the pipe pile body 11 and avoid damage to the pipe pile body 11 or the fastening device due to excessive local force. At the same time, the frame 1 provides solid support for the entire fastening structure, ensuring the stability of the entire structure during transportation and reducing the impact of vibration or impact on the pipe pile and equipment.

[0028] The overall mechanism achieves the following effect: First, the operator uses a crane or hoisting equipment to lift the pipe pile body 11 and place it horizontally on the upper surface of the frame 1. Then, the operator manually rotates the screw 3 by turning the turning block 4, adjusting the position of the detachable locking block 5 to accommodate the length of the pipe pile. Next, the lower fastening ring 6 and the upper fastening ring 7 are fitted onto the outside of the pipe pile body 11 and locked by the studs 8, nuts 9, and locking bolts 10, achieving flexible binding and limiting of the pipe pile body to prevent rolling during transportation. Finally, the traction equipment is connected via the push frame 2, preparing for travel. The traction equipment drags the frame 1 and the moving wheels 123. When encountering emergency braking or deceleration on a downhill slope, the frame 1, due to the large inertia of the pipe pile body 11, tends to slide forward relative to the moving wheels 123. At this time, the buffer mechanism 13 and the balancing mechanism 12 at the bottom of the frame 1 begin to work in conjunction, causing the frame 1 to slide forward relative to the fixed frame 121, compressing the bearing spring 132 and the guide telescopic rod 133 within the buffer groove 131. The receiving spring 132 converts the instantaneous peak load of the pipe pile into elastic potential energy, achieving flexible buffering and preventing rigid impacts that could cause the pipe pile end plate to shatter or break. Simultaneously, the guide telescopic rod 133 ensures stable sliding direction. While the buffer mechanism 13 is compressed, the frame 1 drives the receiving block 126 and the fixed rack 1210 forward. Because the fixed rack 1210 meshes with the gear 124 on the rotating shaft 122, the linear motion of the rack drives the gear 124 to rotate. The gear 124 drives the coaxial rotating shaft 122 and the ratchet 125 to rotate. The rotation of the ratchet 125 is immediately locked by the ratchet 127 connected to the connecting shaft 129 on the L-shaped plate 128, preventing the gear 124 from reversing. Since the ratchet 127 locks the ratchet 125, the gear 124 cannot continue to rotate, thus preventing the frame 1 from sliding forward further via the fixed rack 1210. At this point, the inertial force of the pipe pile body 11 is converted into downward pressure on the ground by the fixed frame 121, causing the moving wheel 123 to press firmly against the ground, generating a counter-torque to resist forward tipping. This effectively prevents the entire vehicle from tipping forward with the front wheels as the fulcrum or the pipe pile from being thrown out. After reaching the target location, the operator releases the locking bolt 10 and nut 9, opens the upper fastening ring 7 and lower fastening ring 6, and uses lifting equipment to remove the pipe pile body 11. The receiving spring 132 in the buffer mechanism 13 automatically rebounds, pushing the fixed frame 121 to reset, the ratchet 127 disengages from the ratchet 125, and the equipment returns to its initial state, ready for the next delivery.

[0029] In terms of structural material selection, the gears 124, fixed racks 1210, ratchet 125, and ratchet 127 in the balancing mechanism 12 are made of high-strength alloy steel and undergo carburizing and quenching treatment to ensure their surface hardness and impact toughness, and to prevent tooth breakage or plastic deformation due to instantaneous peak load during emergency braking; the bearing spring 132 in the buffer mechanism 13 needs to be made of fatigue-resistant alloy spring steel, and its wire diameter and number of turns are designed according to heavy-load conditions to ensure that it can repeatedly absorb the huge inertial impact of the pipe pile body 11 without permanent deformation or breakage; the load-bearing components such as the frame 1, bearing block 126, and L-shaped plate 128 are made of Q355B low-alloy high-strength structural steel, and flaw detection is performed at key welds; at the same time, the inner rings of the lower fastening ring 6 and upper fastening ring 7 that compress the pipe pile body 11 should be lined with rubber pads or nylon linings to prevent hard metal from directly contacting the concrete surface of the pipe pile and causing indentation or local cracking.

[0030] During operation, ensure that the pipe pile body 11 is reliably locked by the lower fastening ring 6 and the upper fastening ring 7 through the stud 8, nut 9 and locking screw block 10. The position of the detachable locking block 5 should be precisely adjusted according to the length of the pipe pile by turning the drive screw 3 through the turning block 4 to avoid improper limit and shaking during transportation. Before driving, check that the bearing spring 132 and the guide telescopic rod 133 in the buffer groove 131 are free from jamming or corrosion, and confirm that the meshing surfaces of the ratchet 125 and the ratchet 127 are clean and free of oil. After long-term use of the equipment, the meshing clearance between the gear 124 and the fixed rack 1210 and the wear of the ratchet teeth of the ratchet 127 should be checked regularly. After each unloading, check whether the bearing spring 132 has been fully reset. Ensure that the fixed frame 121 and the frame 1 are in the initial position before the next loading. At the same time, pay attention to protecting the bearing seals of the rotating shaft 122 and the moving wheel 123 to prevent mud or dust from entering and increasing the rotational resistance, which will affect the braking linkage sensitivity.

[0031] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A precast concrete pipe pile conveying device, characterized in that: The vehicle includes a frame (1), a pusher (2) is fixedly installed on the right side of the upper surface of the frame (1), a balancing mechanism (12) that converts braking force into meshing force is installed on the lower surface of the frame (1), and a buffer mechanism (13) that converts braking force into buffering force is installed on the lower surface of the frame (1). The buffer mechanism (13) avoids damage to the overall braking by buffering.

2. The precast concrete pipe pile conveying equipment according to claim 1, characterized in that: The balancing mechanism (12) includes a fixed frame (121), a rotating shaft (122), a moving wheel (123), a gear (124), a ratchet (125), and a receiving block (126). The upper outer surface of the fixed frame (121) is slidably connected to the inner wall of the bottom of the frame (1). The outer surface of the rotating shaft (122) is rotatably installed with the inner wall of the fixed frame (121). The interior of the moving wheel (123) is fixedly installed with the outer surface of the rotating shaft (122). The interior of the gear (124) is fixedly installed with the outer surface of the rotating shaft (122). One side of the ratchet (125) is fixedly installed with the outer surface of one end of the rotating shaft (122). The upper surface of the receiving block (126) is fixedly installed with the lower surface of the frame (1).

3. The precast concrete pipe pile conveying equipment according to claim 1, characterized in that: The buffer mechanism (13) includes a support spring (132) and a guide telescopic rod (133). A buffer groove (131) is provided on the lower surface of the frame (1). One end of the support spring (132) is fixedly installed inside the buffer groove (131), and one end of the guide telescopic rod (133) is fixedly installed inside the buffer groove (131).

4. The precast concrete pipe pile conveying equipment according to claim 2, characterized in that: A fixed rack (1210) is fixedly installed on the lower surface of the receiving block (126), and the fixed rack (1210) is meshed with the gear (124).

5. A precast concrete pipe pile conveying device according to claim 2, characterized in that: An L-shaped plate (128) is fixedly installed on one side of the receiving block (126), and a connecting shaft (129) is rotatably installed on the inner wall of the L-shaped plate (128).

6. The precast concrete pipe pile conveying equipment according to claim 5, characterized in that: A ratchet (127) is fixedly installed on the outer surface of one end of the connecting shaft (129), and the outer surface of the ratchet (127) engages with the surface of the ratchet bar (125).

7. The precast concrete pipe pile conveying equipment according to claim 3, characterized in that: One end of the receiving spring (132) is fixedly installed on one side of the bottom end of the fixing frame (121), and one end of the guide telescopic rod (133) is fixedly installed on one side of the bottom end of the fixing frame (121).

8. A precast concrete pipe pile conveying device according to claim 1, characterized in that: A screw (3) is rotatably mounted on the inner wall of the frame (1), a screw (4) is fixedly mounted on one end of the screw (3), and a detachable locking block (5) is mounted on the outer surface of the screw (3).

9. A precast concrete pipe pile conveying device according to claim 1, characterized in that: The upper surface of the frame (1) is fitted with a lower fastening ring (6), and the inner wall of the bottom end of the lower fastening ring (6) is threaded onto the outer surface of the screw (3).

10. A precast concrete pipe pile conveying device according to claim 9, characterized in that: The upper surface of the lower fastening ring (6) is fitted with an upper fastening ring (7). The lower fastening ring (6) and the upper fastening ring (7) are fitted with studs (8). One end of the stud (8) is fixedly fitted with a nut (9). The outer surface of the bottom end of the stud (8) is threaded with a locking screw block (10). The inner ring of the lower fastening ring (6) and the upper fastening ring (7) is fitted with a pipe pile body (11).

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