An off-board brake pipe teaching system and method of use thereof

Abstract

The application discloses a kind of undercarriage brake pipeline teaching system and its using method, belong to rail vehicle technical field.The application solves the problem that the end of pipe cannot be detected in the prior art whether it is tightly in the joint body, resulting in poor training effect evaluation effect.The lower surface structure of the support plate is the same as the vehicle floor structure, the bogie is connected to the lower surface of the support plate, and the brake pipeline is arranged on the lower surface of the support plate and the bogie.The joint body of the sleeve pipe joint in the brake pipeline is provided with a boss for contacting with the end surface of the pipe, a through groove is arranged on the contact surface of the boss contacting with the pipe, a piston is slidably arranged in the through groove, the piston is connected with a piston rod, a first gas passage is connected to one side of the through groove away from the piston rod, and the first gas passage is connected with an air bag arranged outside the joint body.The application can intuitively judge the assembly effect of the brake pipeline, which is simple and clear, low in cost, and will not affect the normal assembly of the brake pipeline.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of rail vehicles, and particularly relates to a teaching system for under-vehicle brake pipe and a method for using the same. BACKGROUND

[0002] The braking performance of a subway vehicle guarantees the operation safety of the train, and the quality of the assembly procedure of the brake pipe will directly affect whether the brake system can stably and effectively operate. In order to guarantee the sealing property of the brake pipe, a sleeve pipe joint is generally used to connect the pipes, and whether the sleeve pipe joint is correctly installed will directly affect the sealing property of the pipe. When the sleeve pipe joint is used, the end of the pipe is first tightly pressed in the installation joint body to ensure that the pipe section is in contact with the pre-installed joint body, and then the nut is screwed into the pre-installed joint and tightened.

[0003] Since the assembly precision of the brake pipe is high, beginners generally need to first undergo theoretical training and then perform hands-on training of brake pipe assembly through a real vehicle. Although the assembly training through a real vehicle highly restores the actual scene of real assembly, it is beneficial to improve the training effect, but if the assembly training is performed through a real vehicle, the brake pipe of the real vehicle needs to be repeatedly disassembled and assembled, which has a certain impact on the quality of the real vehicle. Moreover, in the prior art, after the student finishes the assembly, a certain pressure of gas is generally introduced into one end of the pipe, and then the gas pressure is detected at the other end of the pipe. If the gas pressure loss is within the set range, it indicates that there is no leakage, and the assembly is successful. If the gas pressure loss is greater than the set value, it indicates that the assembly does not meet the requirements. Therefore, in the prior art, only the overall gas tightness of the pipe can be judged. If the student does not first tightly press the end of the pipe in the installation joint body when using the sleeve pipe joint, although it will not cause obvious gas leakage at that time, it will affect the long-term use of the brake pipe. Therefore, not first tightly pressing the end of the pipe in the installation joint body is also not in line with the assembly requirements, but the prior art cannot detect this process. SUMMARY

[0004] In view of the problem in the prior art that the end of the pipe cannot be detected whether it is tightly pressed in the joint body during the assembly training process of the brake pipe, resulting in poor evaluation effect of the training, the present application provides a teaching system for under-vehicle brake pipe and a method for using the same.

[0005] The technical solution adopted by the present application is as follows:

[0006] A teaching system for under-vehicle brake pipe, comprising a support frame, the support frame comprising a support plate and support legs, the lower surface structure of the support plate being the same as the structure of the vehicle bottom plate, a bogie being connected to the lower surface of the support plate, and a brake pipe being arranged on the lower surface of the support plate and the bogie.

[0007] The brake pipeline comprises various sleeve pipe joints for connecting pipes and pipes or pipes and brake devices;

[0008] The sleeve pipe joint comprises a joint body, a sleeve and a nut.

[0009] The joint body is provided with a boss for contacting the end face of the pipe, the boss is provided with a through slot on the contact surface contacting the pipe, a piston is slidingly arranged in the through slot, the piston is connected with a piston rod, a first gas passage is connected with the side of the through slot away from the piston rod, and the first gas passage is connected with an air bag arranged outside the joint body.

[0010] After the technical scheme is adopted, the present application changes the existing mode of directly assembling the brake pipeline on the existing vehicle for practical training, a support frame is arranged according to the structure of the existing vehicle, and a bogie is connected on the support frame to simulate the structure of a real railway vehicle, so that the practical training effect is ensured and the existing vehicle is not affected. Secondly, in order to further evaluate whether the assembly of the brake pipeline meets the requirements, the through slot provided with the piston is arranged on the joint body, when the pipe is inserted, the pipe extrudes the piston inward, so that the gas in the through slot is extruded into the air bag to make the air bag expand, if the end portion of the pipe does not abut against the boss, the air bag cannot expand to the set size, therefore, the examiner can directly judge whether the operator contacts the end portion of the pipe with the boss according to the expansion degree of the air bag. The mode can very intuitively judge the assembly effect of the brake pipeline, is simple and clear, has low cost, and will not affect the normal assembly of the brake pipeline.

[0011] As a preferred, the air bag is further connected with a second gas passage, the sleeve extrudes the pipe to form a sealing groove, the second gas passage communicates with the sealing groove, and a gas stop valve is arranged on the second gas passage.

[0012] After the technical scheme is adopted, beginners are difficult to grasp the degree of rotating the nut, and thus it is relatively easy to cause the pipe to be damaged due to excessive clamping of the sleeve, which is one of the main reasons for causing the pipe to leak. In the prior art, if it is further known where the gas leaks, the detection needs to be performed by smearing soap water, which is time-consuming and laborious, and the leakage position cannot be directly known, thereby affecting the teaching effect. After the leakage position is known, the pipe also needs to be disassembled to know the leakage reason; in the application, the second gas passage is arranged to communicate the sealing groove formed at the clamping position of the sleeve and the air bag, and when the air valve is opened, if the clamping position of the sleeve is damaged or the clamping position of the sleeve is not tightly connected with the pipe, the air bag will leak, which indicates that the sleeve type pipe joint at the position is incorrectly connected, and the operator can recall the assembly process of the sleeve type pipe joint at the position to facilitate the summary of the failure reason; if the air bag does not leak, it indicates that the sealing property at the position is good, and it is possible that the pipe itself has a crack. Therefore, the air bag can not only determine whether the pipe is inserted into the bottom of the joint body, but also effectively improve the searching efficiency of the leakage position and the leakage reason, and improve the teaching effect.

[0013] Preferably, one end of the piston rod is connected with a limiting block, a limiting groove matched with the limiting block is arranged on the joint body, a first sealing gasket is arranged in the limiting groove, a second sealing gasket is arranged at the position where the convex platform contacts the pipe end face, and the first sealing gasket is seamlessly connected with the second sealing gasket.

[0014] After the technical scheme is adopted, the connection tightness of the pipe end face and the joint body can be improved by cooperation of the second sealing gasket and the first sealing gasket, and the sealing groove is further in a sealed state.

[0015] Preferably, a shield cover which can be opened and closed is arranged outside the air bag.

[0016] After the technical scheme is adopted, since the air bag is not used to determine whether the pipe is inserted into the bottom of the joint body in the real assembly process, the shield cover can be closed during the real examination to avoid the operator from determining whether the pipe is inserted into the bottom according to the air bag, which is closer to the real assembly process; and during the daily training process, whether the pipe is inserted into the bottom can be determined according to the air bag, and the hand feeling can be trained.

[0017] In addition, whether the air bag is sufficiently inflated can be determined according to whether the air bag contacts the shield cover, the shield cover is closed during the examination, and after the examination is completed, the shield cover is opened, and whether the examination is qualified is determined according to whether the air bag contacts the shield cover.

[0018] Preferably, a pressure sensor is arranged on the inner surface of the shield cover, and the pressure sensor is electrically connected with a control system.

[0019] According to the technical scheme, since multiple sleeve pipe joints exist in the brake pipe, it is not objective and is relatively troublesome to observe the inflation state of the air bag by naked eyes, therefore, the pressure sensor is arranged in the shielding cover, the air bag can contact the pressure sensor to cause the pressure value to change when the air bag is inflated to a set degree, the control system can analyze the pressure value detected by the pressure sensor to determine whether the air bag is inflated to the set range, and the evaluation efficiency of the brake pipe assembly is improved.

[0020] Preferably, the piston is provided with a spring on the side close to the first gas passage.

[0021] According to the technical scheme, since the teaching system is repeatedly used, the spring is arranged to push the piston back to the original position after the pipe is disassembled, so as to facilitate the next assembly.

[0022] A use method of the off-vehicle brake pipe teaching system, which is performed by using the off-vehicle brake pipe teaching system, and includes the following steps.

[0023] Step 1: an operator assembles the brake pipe on the support plate and the bogie;

[0024] Step 2: an examiner determines whether the pipe abuts against the boss on the joint body according to the inflation degree of the air bag on each sleeve pipe joint, if all the air bags are inflated to a set size, it is indicated that the pipe abuts against the boss on the joint body, then step 3 is performed, if at least one air bag is not inflated to the set range, it is indicated that the pipe does not abut against the boss on the joint body, then it is determined that the examination fails, and then step 3 is performed or the examination and evaluation are directly ended;

[0025] Step 3: gas is introduced into one end of the connected brake pipe, the gas pressure at the other end of the brake pipe is detected, and the loss amount of the gas pressure is obtained, if the loss amount of the gas pressure is within a set range, it is indicated that the gas tightness meets the requirements, if the loss amount of the gas pressure is not within the set range, it is indicated that the gas tightness does not meet the requirements.

[0026] Preferably, the air bag is further connected with a second gas passage, the sleeve extrudes the pipe to form a sealing groove, the second gas passage communicates with the sealing groove, and a gas stop valve is arranged on the second gas passage.

[0027] Step 4 is further included, and the specific steps of step 4 are as follows: when the gas tightness does not meet the requirements, the gas stop valves are opened, if the air bag is deflated, it is indicated that the sleeve joint of the pipe is damaged or is not connected tightly.

[0028] In summary, since the above technical scheme is adopted, the beneficial effects of the present application are as follows:

[0029] 1. The present application changes the existing way of directly assembling brake pipeline on the existing vehicle, supports are arranged according to the structure of the existing vehicle, and a bogie is connected on the support to simulate the structure of a real railway vehicle, so that the training effect is ensured and the existing vehicle is not affected.

[0030] 2. In order to further evaluate whether the assembly of the brake pipeline meets the requirements, a through groove provided with a piston is arranged on the joint body, the piston is pressed inward when the pipeline is inserted, so that the gas in the through groove is pressed into the air bag to make the air bag expand, if the end of the pipeline does not abut against the boss, the air bag cannot expand to the set size, therefore the examiner can directly judge whether the operator contacts the end of the pipeline with the boss according to the degree of expansion of the air bag. The way can directly judge the assembly effect of the brake pipeline, which is simple, clear and low in cost, and will not affect the normal assembly of the brake pipeline.

[0031] 3. In the present application, the second gas passage is arranged to communicate the sealing groove formed by the air bag and the sleeve joint, when the air valve is opened, if the sleeve joint is damaged or the sleeve joint is not tightly connected with the pipeline, the air bag will leak, which indicates that the sleeve joint connection at this position is wrong, the operator can recall the assembly process of the sleeve joint at this position to facilitate the summary of the failure reason; if the air bag does not leak, it indicates that the sealing at this position is good, and there may be a crack in the pipeline itself. Therefore, through the air bag, it can not only judge whether the pipeline is inserted to the bottom of the joint body, but also effectively improve the searching efficiency of the leakage position and the leakage reason, and improve the teaching effect. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a structural schematic view of the present application;

[0033] Figure 2 is a structural schematic view of the sleeve joint in the sleeve joint pipe joint of the present application when the sleeve is not clamped;

[0034] Figure 3 is a structural schematic view of the sleeve joint in the sleeve joint pipe joint of the present application when the sleeve is not clamped; Figure 2

[0035] Figure 4 is a structural schematic view of the sleeve joint in the sleeve joint pipe joint of the present application when the sleeve is not clamped;

[0036] Figure 5 is a structural schematic view of the sleeve joint in the sleeve joint pipe joint of the present application when the sleeve is not clamped; Figure 4

[0037] Figure 6 is a structural schematic view of the present application when the shielding cover is arranged;

[0038] ​​Wherein, 1 - support plate, 2 - support leg, 3 - brake pipeline, 4 - bogie, 5 - nut, 6 - sleeve, 7 - joint body, 8 - second gas passage, 9 - gas valve, 10 - air bag, 11 - first gas passage, 12 - piston, 13 - piston rod, 14 - spring, 15 - sealing groove, 16 - shield cover. DETAILED DESCRIPTION

[0039] To make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0040] In the description of the embodiments of the present application, it should be noted that the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, or the orientations or positional relationships in which the product of the present application is usually placed, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third", etc. are only used for differentiation in description, and cannot be understood as indicating or implying relative importance.

[0041] Embodiment 1

[0042] A vehicle under-brake pipeline teaching system, comprising a support frame, the support frame comprising a support plate 1 and a support leg 2, the lower surface structure of the support plate 1 being the same as the vehicle floor structure, a bogie 4 being connected to the lower surface of the support plate 1, a brake pipeline 3 being arranged on the lower surface of the support plate 1 and the bogie 4;

[0043] The brake pipeline 3 comprises various sleeve type pipe joints for connecting pipes and pipes or pipes and brake equipment;

[0044] The sleeve type pipe joint comprises a joint body 7, a sleeve 6 and a nut 5;

[0045] The joint body 7 is provided with a boss for contacting with the pipe end face, the boss is provided with a through slot on the contacting surface with the pipe, the through slot is slidably provided with a piston 12, the piston 12 is connected with a piston rod 13, the through slot is connected with a first gas passage 11 on the side away from the piston rod 13, and the first gas passage 11 is connected with the air bag 10 arranged outside the joint body 7.

[0046] In the embodiment, the structure related to the brake pipe on the bogie 4 is the same as that of the existing vehicle in structure, position and size, and unrelated structures can not be arranged to reduce the manufacturing cost of the teaching system.

[0047] In the embodiment, the air bag 10 is an elastic air bag which can expand with the increase of gas.

[0048] Embodiment 2

[0049] The embodiment is basically the same as embodiment 1, and the difference is that the air bag 10 is further connected with a second gas passage 8, the sleeve 6 extrudes the pipe to form a sealing groove 15, the second gas passage 8 communicates with the sealing groove 15, and the second gas passage 8 is provided with a gas stop valve 9. The second gas passage 8 is partially arranged in the joint body 7 and partially arranged outside the joint body 7, the gas stop valve 9 is arranged on the second gas passage 8 arranged outside the joint body 7, the structure of the gas stop valve 9 is the same as that of the flow regulating valve during infusion, and the second gas passage 8 can be opened or closed through the gas stop valve. One end of the piston rod 13 is connected with a limiting block, the joint body 7 is provided with a limiting groove matched with the limiting block, the limiting groove is internally provided with a first sealing gasket, the boss is provided with a second sealing gasket at the contacting position with the pipe end face, and the first sealing gasket is seamlessly connected with the second sealing gasket. The second gas passage 8 is arranged to communicate the air bag 10 with the sealing groove 15 formed at the clamping position of the sleeve 6, if the sleeve 6 clamping contact is damaged or the clamping position of the sleeve 6 is not tightly connected with the pipe after the gas stop valve 9 is opened, the air bag will deflate, which indicates that the sleeve type pipe joint at the position is incorrectly connected, the operator can review the assembly process of the sleeve type pipe joint at the position to facilitate the summary of the failure reason, and if the air bag 10 does not deflate, it indicates that the sealing property at the position is good, and it is possible that the pipe itself has a crack. Therefore, the air bag 10 can not only determine whether the pipe is inserted to the bottom of the joint body, but also effectively improve the searching efficiency of the leakage position and the leakage reason, and improve the teaching effect.

[0050] Embodiment 3

[0051] The embodiment is basically the same as embodiment 2, and the difference is that Figure 6As shown, the air bag 10 is externally provided with a closable shielding cover 16, the shielding cover 16 is provided with a through slot for the second gas passage 8 to extend out of the shielding cover, the second gas passage 8 extends out of the through slot, the shielding cover 16 is made of black opaque plastic material, the plastic material is light in weight, the air bag 10 can be covered in the shielding cover 16, one end of the shielding cover 16 is hinged to the joint body 7, the other end is provided with a clamping head, the joint body 7 is provided with a clamping groove matched with the clamping head, the closing of the shielding cover 16 is realized through the matching of the clamping head and the clamping groove. In other embodiments, the shielding cover 16 can also be made of other opaque materials as long as it can play a shielding role.

[0052] Embodiment 4

[0053] The embodiment is basically the same as embodiment 3, the difference is that in this embodiment, the inner surface of the shielding cover 16 is provided with a pressure sensor, and the pressure sensor is electrically connected with a control system. Since there are multiple sleeve type pipe joints in the brake pipeline 3, it is not objective and more troublesome to observe the inflation state of the air bag with the naked eye, therefore, a pressure sensor is directly arranged in the shielding cover 16, when the air bag inflates to a certain extent, it can contact the pressure sensor to cause the pressure value to change, the control system can analyze the pressure value detected by the pressure sensor to determine whether the air bag inflates to a certain range, thereby improving the evaluation efficiency of the brake pipeline assembly.

[0054] Embodiment 5

[0055] A use method of a vehicle under-brake pipeline teaching system, which is carried out by using the vehicle under-brake pipeline teaching system of embodiment 4, and includes the following steps.

[0056] Daily training:

[0057] Step 1: During daily training, the operator assembles the brake pipeline 3 on the support plate 1 and the bogie 4 according to the content of the theoretical training, inserts the pipeline end into the bottom of the joint body 7 during assembly, judges whether the pipeline end surface abuts against the boss according to the inflation state of the air bag 10, trains the sense of touch, and rotates the nut 5 according to the requirements after the pipeline end surface abuts against the boss, so that the sleeve 6 is clamped into the pipeline.

[0058] Step 2: Open the air stop valve 9, check whether the air bag 10 is deflated, if it is deflated, it indicates that the clamping position of the sleeve 6 of the pipeline is damaged or not tightly connected, then the assembly process is adjusted and the pipeline is replaced for next training.

[0059] Training achievement assessment:

[0060] Step 1: In the state that the shielding cover 16 covers the air bag 10, the operator assembles the brake pipeline 3 on the support plate 1 and the bogie 4 according to the content of the theoretical training.

[0061] Step 2: The examiner determines whether the air bags 10 are in contact with the protrusions on the joint body 7 according to the pressure values of the pressure sensors obtained by the control system. If all the air bags 10 are inflated to the set size, it means that the pipe is in contact with the protrusions on the joint body 7, and then step 3 is continued. If at least one air bag 10 is not inflated to the set size, it means that the pipe is not in contact with the protrusions on the joint body 7, and then the evaluation is determined to be failed, and then step 3 is continued or the evaluation is directly ended.

[0062] Step 3: Gas is introduced into one end of the connected brake pipe 3, the gas pressure at the other end of the brake pipe 3 is detected, and the loss amount of the gas pressure is obtained. If the loss amount of the gas pressure is within the set range, it means that the air tightness meets the requirements. If the loss amount of the gas pressure is not within the set range, it means that the air tightness does not meet the requirements.

[0063] Step 4: When the air tightness does not meet the requirements, the stop valves 9 are opened. If there is air leakage of the air bags 10, it means that the clamping sleeve 6 clamping part of the pipe is damaged or not tightly connected.

[0064] In other embodiments, the stop valves 9 can also be set as electric valves. The control system controls the opening of each stop valve 9, and the pressure sensor monitors the change of the pressure in real time. If the pressure monitored by the pressure sensor becomes smaller after the stop valve 9 is opened, it means that there is air leakage. If the detected pressure has little change, it means that the air tightness is good. In this way, the automatic monitoring of the air leakage position is realized, and the manpower is saved.

[0065] The above embodiments only express the specific implementation of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the protection scope of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the technical concept of the present application, some modifications and improvements can be made, which are within the protection scope of the present application.

Claims

1. A vehicle brake line teaching system, characterized by: The vehicle comprises a support frame, the support frame comprising a support plate (1) and support legs (2), the lower surface structure of the support plate (1) being identical to the vehicle floor structure, the lower surface of the support plate (1) being connected to a bogie (4), and a brake line (3) being provided on the lower surface of the support plate (1) and the bogie (4); The brake pipeline (3) comprises various ferrule-type pipe joints for connecting pipelines to pipelines or pipelines to brake equipment; The ferrule-type pipe joint comprises a joint body (7), a ferrule (6) and a nut (5); The connector body (7) is provided with a boss for contacting the end face of the pipeline, a through groove is provided on the contact surface of the boss and the pipeline, a piston (12) is slidably provided in the through groove, the piston (12) is connected to a piston rod (13), the through groove is connected to a first gas channel (11) on a side away from the piston rod (13), and the first gas channel (11) is connected to an air bag (10) provided outside the connector body (7).

2. The under-vehicle brake line teaching system according to claim 1, characterized in that: The air bag (10) is also connected to a second gas channel (8), the ferrule (6) squeezes the pipeline to form a sealing groove (15), the second gas channel (8) is communicated with the sealing groove (15), and a gas stop valve (9) is provided on the second gas channel (8).

3. The under-vehicle brake line teaching system according to claim 2, characterized in that: One end of the piston rod (13) is connected to a limiting block, and a limiting groove cooperating with the limiting block is provided on the joint body (7). A first sealing gasket is provided in the limiting groove, and a second sealing gasket is provided at the contact point between the boss and the pipe end face. The first sealing gasket and the second sealing gasket are seamlessly connected.

4. The under-vehicle brake line teaching system according to claim 1, characterized in that: An openable and closable shielding cover (16) is provided outside the airbag (10).

5. The under-vehicle brake line teaching system according to claim 4, characterized in that: A pressure sensor is provided on the inner surface of the shielding cover (16), and the pressure sensor is electrically connected to a control system.

6. The under-vehicle brake line teaching system according to claim 1, characterized in that: A spring (14) is provided on one side of the piston (12) close to the first gas channel (11).

7. A method for using an under-vehicle brake line teaching system, characterized by: The method is carried out using the vehicle brake line teaching system according to any one of claims 1 to 6, comprising the following steps: Step 1: The operator assembles the brake pipe (3) on the support plate (1) and the bogie (4); Step 2: The examiner judges whether the pipe is in contact with the boss on the joint body (7) according to the expansion degree of the airbags (10) on each ferrule-type pipe joint. If all the airbags (10) are expanded to the set size, it means that the pipe is in contact with the boss on the joint body (7), and then proceed to step 3. If at least one airbag (10) is not expanded to the set range, it means that the pipe is not in contact with the boss on the joint body (7), and then the examination is judged to have failed. Then proceed to step 3 or directly end the examination and evaluation. Step 3: Introduce gas into one end of the connected brake pipe (3), detect the gas pressure at the other end of the brake pipe (3), and obtain the air pressure loss. If the air pressure loss is within the set range, it means that the air tightness meets the requirements. If the air pressure loss is not within the set range, it means that the air tightness does not meet the requirements.

8. The method for using the under-vehicle brake line teaching system according to claim 7, characterized in that: The air bag (10) is also connected to a second gas channel (8), the ferrule (6) squeezes the pipeline to form a sealing groove (15), the second gas channel (8) is communicated with the sealing groove (15), and a gas stop valve (9) is provided on the second gas channel (8); The method further includes step 4, wherein the specific steps of step 4 are as follows: when the air tightness does not meet the requirements, each air stop valve (9) is opened, and if there is air in the air bag (10) that is deflated, it indicates that the clamping part of the pipe sleeve (6) is damaged or the connection is not tight.

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