A general anti-toppling test device for downhole pick-up sensors

Abstract

A kind of general anti-toppling test device of downhole pick-up sensor, guide rod is arranged in the middle part of the left end of test box;Slide sleeve is sleeved in the middle part of guide rod, and a pair of continuous racks are fixed to the front and back thereof;Two gears are respectively sleeved in the end part of two rotating shafts, and are respectively engaged with a pair of continuous racks, and a straight connecting rod is further connected on the rotating shaft, and a metal ball is fixed to the end of the straight connecting rod;Two first connecting rods are symmetrically distributed above two rotating shafts, and a first fixed pulley is connected on each of the two first connecting rods;Two second connecting rods are symmetrically distributed on the outer side above two first connecting rods, and a second fixed pulley is connected on each of the two second connecting rods;Two bearing cavities are evenly separated into multiple pairs of containing spaces in length direction;Four protective pads are arranged around the top and bottom of each containing space;Cable connecting rod is arranged in the transmission space, and cable fixer is arranged on the cable connecting rod.The device can avoid the accidental toppling of sensor during testing.

Description

Technical Field

[0001] This invention belongs to the technical field of seismic sensor testing devices, specifically relating to a universal anti-tipping testing device for downhole seismic sensors. Background Technology

[0002] Microseismic systems commonly used in coal mines enable long-distance, real-time, and dynamic monitoring of mine seismic signals, providing complete waveform data. This facilitates accurate calculation of the occurrence time, energy, and three-dimensional spatial coordinates of seismic events with energies exceeding 100J, thereby helping to determine the type of each seismic event, identify the force source, and assess the severity of mine rockburst hazards. The seismic sensors used in these systems are typically installed on the floor of mine roadways. These sensors are prone to damage and have poor adaptability to the complex and harsh underground environment. During use, they are frequently struck or bumped by other equipment, leading to wire breaks. Therefore, the operational status of the seismic sensors needs to be tested before use and after maintenance. Currently, there is a lack of effective protection measures for vibration sensors, or there are no protection measures at all. This can easily cause abnormalities to occur before the probe is even used. In addition, during the testing process after damage and repair, improper operation can cause secondary damage to the internal components of the vibration sensor. Therefore, there is an urgent need to provide a testing device that can effectively protect the vibration sensor and can quickly, stably and reliably complete the vibration sensor testing operation. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a universal anti-tipping testing device for downhole seismic sensors. This device has a simple structure, is easy to maintain, and has low manufacturing cost. It can effectively protect the seismic sensors and prevent them from accidentally tipping over during testing. At the same time, it can complete the testing process quickly, stably, and reliably.

[0004] This invention provides a universal anti-tipping test device for downhole seismic sensors, including a test box, a guide rod, a sliding sleeve, a handle, a rotating shaft, a gear, a first connecting rod, and a second connecting rod; the test box has an opening at the top, its length extends in the left-right direction, and its width extends in the front-back direction;

[0005] The internal space of the test chamber is divided in the width direction into a conductive cavity located in the middle and two bearing cavities symmetrically distributed on the front and rear sides of the conductive cavity. A partition is provided at the junction of the conductive cavity and the two bearing cavities. The partition extends along the length direction of the test chamber, and its two ends are fixedly connected to the left and right side panels of the test chamber, respectively.

[0006] The guide rod is vertically positioned at one end of the test chamber along its length and located in the middle of the conductive cavity; the lower end of the guide rod is fixedly connected to the bottom plate of the test chamber, and its upper end extends to the upper end of the test chamber.

[0007] The sliding sleeve is axially slidable and radially limited and is fitted onto the outer side of the middle part of the guide rod. A pair of continuous racks are fixedly connected to its front and rear parts in a symmetrical manner. A strip-shaped groove is opened on the left side panel of the test box corresponding to the sliding sleeve.

[0008] The grip is located on the outside of the test chamber and is fixedly connected to the lower end of the slide sleeve by a crossbar passing through the slide groove.

[0009] Two rotating shafts are located inside the conduction cavity and are symmetrically distributed on the outside of a pair of continuous racks, with their two ends rotatably connected to the left and right side panels of the test chamber, respectively.

[0010] Two gears are fixedly mounted on the ends of two rotating shafts and mesh with a pair of continuous racks respectively;

[0011] The two first connecting rods are located on the inner front and inner rear sides of the conduction cavity, respectively, and are symmetrically distributed above the two rotating shafts. Their two ends are rotatably connected to the left and right side panels of the test chamber, respectively.

[0012] Two second connecting rods are located on the outer front and outer rear sides of the conduction cavity, and are symmetrically distributed on the outer side above the two first connecting rods. Their two ends are rotatably connected to the left and right side panels of the test chamber, respectively.

[0013] Two supporting cavities are evenly divided into multiple pairs of receiving spaces along their length. Each receiving space extends vertically, and four protective pads are provided around its top and bottom. The four protective pads around the top are located below the first and second connecting rods. The two protective pads at the top of two adjacent receiving spaces are an integral structure, with their outermost end fixedly connected to the outer panel of the test chamber via the first connecting plate, and their innermost end fixedly connected to the partition via the second connecting plate. The inner protective pad at the top of each receiving space is fixedly connected to the partition, and the remaining outer protective pads are fixedly connected to the test chamber. Hollow areas are provided between the two protective pads at the top and bottom on the inner side and between the two protective pads at the top and bottom on the outer side of each receiving space.

[0014] The conductive cavity is uniformly equipped with multiple test units along its length, each test unit corresponding to multiple pairs of accommodating spaces. Each test unit consists of two straight connecting rods, two small metal balls, two first fixed pulleys, two second fixed pulleys, a cable connecting rod, and two cable retainers. The two straight connecting rods are of the same length and are symmetrically arranged front to back, with their upper ends fixedly connected to two rotating shafts respectively. The two small metal balls are fixedly connected to the lower ends of the two straight connecting rods respectively, and can enter the hollow area during the swinging of the straight connecting rods. The two first fixed pulleys are located on the right side of the two straight connecting rods and are symmetrically arranged front to back, and are respectively connected to the two first connecting rods. The two second fixed pulleys are located outside the two first fixed pulleys and are symmetrically arranged front to back, and are respectively connected to the two second connecting rods. The cable connecting rod is located above the two first connecting rods, and its two ends are fixedly connected to the left and right panels of the test chamber respectively. The two cable retainers are located between the two first fixed pulleys and are symmetrically fixedly connected to the cable connecting rod.

[0015] Furthermore, to ensure the impact effect and the service life of the connecting rod, the connecting rod is made of a tough metal material. In order to allow the metal ball to impact the vibration sensor at different initial positions, thereby meeting the sensor's needs for testing different vibrations, the upper end of the connecting rod is connected to the rotating shaft through an angle-adjustable connecting rod. The angle-adjustable connecting rod allows the connection angle of the connecting rod relative to the rotating shaft to be adjusted.

[0016] As a preferred embodiment, the four protective pads around the top and bottom of each containment space have arc-shaped grooves on their adjacent sides.

[0017] Furthermore, to improve testing efficiency, the number of the accommodating spaces is 16 pairs.

[0018] Furthermore, both the first and second fixed pulleys have annular grooves, the size of which is adapted to the size of the cable connected to the vibration sensor under test. This not only provides better guidance but also better restraint on the cable, preventing excessive cable length or number from causing tangling and adversely affecting sensor testing.

[0019] Furthermore, in order to limit the sliding stroke of the sleeve, an upper limit ring and a lower limit ring are fixedly fitted on the guide rod above and below the sleeve, respectively. The upper limit ring and the lower limit ring are used to limit the sliding stroke of the sleeve on the guide rod.

[0020] In this invention, the vertical extension of the accommodating space facilitates the vertical accommodating of the vibration sensor to be tested. Four protective pads are provided around the top and bottom of each accommodating space to effectively prevent the vibration sensor from accidentally tipping over during testing. A first directional pulley and a second directional pulley are provided on each side of the accommodating space. Additionally, two cable holders are provided in the middle, which can be used by both accommodating spaces. This ensures that the vibration sensor cable is fixed in a predetermined direction, preventing excessive cable length or tangling that could adversely affect the test. It also prevents damage to the internal components of the vibration sensor caused by cable dragging during testing. The sliding sleeve is vertically slidable on the guide rod, with continuous racks on both its front and rear sides. These racks, along with two gears fixedly mounted on two rotating shafts, allow the sliding sleeve to rotate during its movement. Metal balls are connected to these shafts via straight connecting rods. As the shafts rotate, the metal balls oscillate. Because there is a hollow area between the two protective pads near the inner side of each receiving space, the oscillating metal balls impact the vibration sensor. The signal collected by the sensor is received by the signal acquisition station, enabling the sensor testing process. A strip-shaped groove corresponding to the sliding sleeve is provided on the left side panel of the test chamber. A handle located on the outside of the test chamber is fixedly connected to the sliding sleeve via a horizontal connecting rod, allowing the operator to easily move the sliding sleeve using the handle, thus facilitating the testing process. This device has a simple structure, convenient maintenance, low manufacturing cost, strong practicality, and high testing efficiency. During testing, it can effectively protect the vibration sensor from tipping over due to accidents and ensure that the internal components of the vibration sensor are not damaged during the testing process. This device is suitable for testing sensors before they are released from the warehouse or after they have been damaged and repaired. Attached Figure Description

[0021] Figure 1 This is a partial structural schematic diagram of the present invention;

[0022] Figure 2 yes Figure 1 The left view;

[0023] Figure 3 This is a schematic diagram of the overall structure of the present invention.

[0024] In the diagram: 1. Accommodation space, 2. Protective pad, 3. Hollow area, 4. First fixed pulley, 5. Cable holder, 6. Gear, 7. Straight connecting rod, 8. Metal ball, 9. Continuous rack, 10. Handle, 11. Test box, 12. Guide rod, 13. Sliding sleeve, 14. Rotating shaft, 15. First connecting rod, 16. Second connecting rod, 17. Partition, 18. Cable connecting rod, 19. Conducting cavity, 20. Bearing cavity, 21. Second fixed pulley, 22. Horizontal connecting rod, 23. First connecting plate, 24. Second connecting plate, 25. Vibration sensor, 26. Cable, 27. Upper limit ring, 28. Lower limit ring. Detailed Implementation

[0025] The invention will now be further described with reference to the accompanying drawings.

[0026] like Figures 1 to 3 As shown, a general anti-tipping test device for downhole seismic sensors includes a test box 11, a guide rod 12, a sliding sleeve 13, a handle 10, a rotating shaft 14, a gear 6, a first connecting rod 15, and a second connecting rod 16; the test box 11 has an opening at the top, its length extends along the left and right direction, and its width extends along the front and back direction.

[0027] The internal space of the test chamber 11 is divided in the width direction into a conductive cavity 19 located in the middle and two bearing cavities 20 symmetrically distributed on the front and rear sides of the conductive cavity 19. A partition 17 is provided at the junction of the conductive cavity 19 and the two bearing cavities 20. The partition 17 extends along the length direction of the test chamber 11 and its two ends are fixedly connected to the left and right side panels of the test chamber 11, respectively.

[0028] The guide rod 12 is vertically disposed at one end of the test chamber 11 along its length and is located in the middle of the conduction cavity 19; the lower end of the guide rod 12 is fixedly connected to the bottom plate of the test chamber 11, and its upper end extends to the upper end of the test chamber 11.

[0029] The sliding sleeve 13 is axially slidable and radially limited and is fitted on the outer side of the middle part of the guide rod 12. A pair of continuous racks 9 are fixedly connected to its front and rear parts in a symmetrical manner. A strip-shaped groove is opened on the left side panel of the test box 11 corresponding to the sliding sleeve 13.

[0030] The grip 10 is located on the outside of the test chamber 11 and is fixedly connected to the lower end of the slide sleeve 13 by a cross link 22 passing through the slide groove.

[0031] Two rotating shafts 14 are located inside the conduction cavity 19 and are symmetrically distributed on the outside of a pair of continuous racks 13, and their two ends are rotatably connected to the left and right side panels of the test chamber 11, respectively.

[0032] Two gears 6 are fixedly mounted on the ends of two rotating shafts 14, and respectively mesh with a pair of continuous racks 13;

[0033] The two first connecting rods 15 are located on the inner front and inner rear sides of the conduction cavity 19, respectively, and are symmetrically distributed above the two rotating shafts 14. Their two ends are rotatably connected to the left and right side panels of the test chamber 11, respectively.

[0034] Two second connecting rods 16 are located on the outer front and outer rear sides of the conduction cavity 19, and are symmetrically distributed on the outer side above the two first connecting rods 15. Their two ends are rotatably connected to the left and right side panels of the test chamber 11, respectively.

[0035] Two supporting cavities 20 are evenly divided into multiple pairs of receiving spaces 1 along their length. The size of each receiving space 1 is adapted to the size of the vibration pickup sensor 25 to be tested. Each receiving space 1 extends vertically, and four protective pads 2 are provided around its top and bottom. The four protective pads 2 around its top are located below the first connecting rod 15 and the second connecting rod 16. The two protective pads 2 at the top of two adjacent receiving spaces 1 are an integral structure. The outer end of the pad is fixedly connected to the outer panel of the test chamber 11 through the first connecting plate 23, and the inner end is fixedly connected to the partition plate 17 through the second connecting plate 24. The inner protective pad 2 at the top of each receiving space 1 is fixedly connected to the partition plate 17, and the remaining outer protective pads 2 are fixedly connected to the test chamber 11. A hollow area 3 is provided between the two protective pads 2 at the top and bottom on the inner side and between the two protective pads 2 at the top and bottom on the outer side of each receiving space 1.

[0036] As a preferred option, the protective pad 2 is made of rubber material.

[0037] Multiple test units are evenly arranged along the length of the conductive cavity 19, and the multiple test units correspond to multiple pairs of accommodating spaces 1. Each test unit consists of two straight connecting rods 7, two small metal balls 8, two first fixed pulleys 4, two second fixed pulleys 21, a cable connecting rod 18, and two cable retainers 5. The two straight connecting rods 7 are of the same length and are arranged symmetrically front to back. Their upper ends are fixedly connected to two rotating shafts 14, and the two small metal balls 8 are fixedly connected to the lower ends of the two straight connecting rods 7, and can enter the hollow region 3 during the swinging of the straight connecting rods 7. Two first fixed pulleys 4 are located on the right side of the two straight connecting rods 7 and are arranged symmetrically front to back, and are respectively connected to the two first connecting rods 15. Two second fixed pulleys 21 are located on the outside of the two first fixed pulleys 4 and are arranged symmetrically front to back, and are respectively connected to the two second connecting rods 16. The cable connecting rod 18 is located above the two first connecting rods 15, and its two ends are respectively fixedly connected to the left and right box panels of the test box 11. Two cable retainers 5 are located between the two first fixed pulleys 4 and are fixedly connected symmetrically front to back to the cable connecting rod 18.

[0038] To ensure the impact effect and the service life of the connecting rod, the connecting rod 7 is made of a tough metal material. To allow the metal ball to impact the vibration sensor at different initial positions, thus meeting the sensor's requirements for testing different vibrations and accommodating diverse testing needs, the upper end of the connecting rod 7 is connected to the rotating shaft 14 via an angle-adjustable connecting rod. The angle-adjustable connecting rod allows the connection angle of the connecting rod 7 relative to the rotating shaft 14 to be adjusted. This allows multiple connecting rods 7 connected to the same rotating shaft 14 to be at different connection angles, thereby placing the corresponding metal ball 8 in different positions.

[0039] As a preferred embodiment, the four protective pads 2 around the top and bottom of each receiving space 1 have arc-shaped grooves on their adjacent sides.

[0040] The number of accommodating spaces 1 is 16 pairs. In this way, 32 vibration sensors 25 can be tested simultaneously, further improving testing efficiency.

[0041] Both the first fixed pulley 4 and the second fixed pulley 21 have annular grooves, the size of which is adapted to the size of the cable 26 connected to the vibration sensor 25 under test. This not only provides better guidance but also better restraint on the cable 26, preventing the cable 26 from becoming too long or too numerous, which could lead to tangling and adversely affect the sensor test.

[0042] To limit the sliding stroke of the sleeve, an upper limit ring 27 and a lower limit ring 28 are fixedly fitted on the guide rod 12 above and below the sleeve 13, respectively. The upper limit ring 27 and the lower limit ring 28 are used to limit the sliding stroke of the sleeve 13 on the guide rod 12. Preferably, a return spring is provided between the upper limit ring 27 and the upper end of the sleeve 13. The return spring is sleeved on the outside of the guide rod 12. By providing the return spring, the sleeve 13 can be pulled back to its initial position after the external force is removed, which facilitates the next test process.

[0043] In this invention, the vertical extension of the accommodating space facilitates the vertical accommodating of the vibration sensor to be tested. Four protective pads are provided around the top and bottom of each accommodating space to effectively prevent the vibration sensor from accidentally tipping over during testing. A first directional pulley and a second directional pulley are provided on each side of the accommodating space. Additionally, two cable holders are provided in the middle, which can be used by both accommodating spaces. This ensures that the vibration sensor cable is fixed in a predetermined direction, preventing excessive cable length or tangling that could adversely affect the test. It also prevents damage to the internal components of the vibration sensor caused by cable dragging during testing. The sliding sleeve is vertically slidable on the guide rod, with continuous racks on both its front and rear sides. These racks, along with two gears fixedly mounted on two rotating shafts, allow the sliding sleeve to rotate during its movement. Metal balls are connected to these shafts via straight connecting rods. As the shafts rotate, the metal balls oscillate. Because there is a hollow area between the two protective pads near the inner side of each receiving space, the oscillating metal balls impact the vibration sensor. The signal collected by the sensor is received by the signal acquisition station, enabling the sensor testing process. A strip-shaped groove corresponding to the sliding sleeve is provided on the left side panel of the test chamber. A handle located on the outside of the test chamber is fixedly connected to the sliding sleeve via a horizontal connecting rod, allowing the operator to easily move the sliding sleeve using the handle, thus facilitating the testing process. This device has a simple structure, convenient maintenance, low manufacturing cost, strong practicality, and high testing efficiency. During testing, it can effectively protect the vibration sensor from tipping over due to accidents and ensure that the internal components of the vibration sensor are not damaged during the testing process. This device is suitable for testing sensors before they are released from the warehouse or after they have been damaged and repaired.

[0044] Working principle:

[0045] First, place the multiple vibration sensors 25 to be tested head down into the receiving space 1, and make the cable 26 of each vibration sensor 25 pass around the second fixed pulley 21 and the first fixed pulley 4 on the corresponding side in sequence, and then connect it to the signal acquisition station through the cable retainer 5. Then, adjust the initial angle of the straight connecting rod 7 according to the test requirements, pull down the handle 10, and drive the sleeve 13 to move downward through the horizontal connecting rod 22. Then, the continuous rack 9 drives the two gears 6 to rotate at the same time. During the rotation of the two gears 6, the two rotating shafts 14 are driven to rotate, which in turn causes the straight connecting rod 7 connected to the two rotating shafts 14 to swing. During the swing of the straight connecting rod 7, the metal ball 8 at its bottom end hits the hollow area 3 on the inner side until it hits the vibration sensor 25 in the receiving space 1, so that the vibration sensor 25 transmits the vibration signal received at different times to the signal acquisition station. Finally, the working status of the sensor is tested by observing the arrival time, integrity and quality of the waveform signal.

Claims

1. A universal anti-tipping testing device for downhole seismic sensors, comprising a test housing (11), wherein the test housing (11) has an opening at its upper end, extends horizontally in its length direction, and extends forward-backward in its width direction; characterized in that, It also includes a guide rod (12), a sliding sleeve (13), a grip (10), a pivot (14), a gear (6), a first link (15), and a second link (16); The internal space of the test chamber (11) is divided in the width direction into a conductive cavity (19) located in the middle and two bearing cavities (20) symmetrically distributed on the front and rear sides of the conductive cavity (19). A partition (17) is provided at the junction of the conductive cavity (19) and the two bearing cavities (20). The partition (17) extends along the length direction of the test chamber (11) and its two ends are fixedly connected to the left and right side panels of the test chamber (11). The guide rod (12) is vertically arranged at one end of the test chamber (11) along its length and is located in the middle of the conduction cavity (19); the lower end of the guide rod (12) is fixedly connected to the bottom plate of the test chamber (11), and its upper end extends to the upper end of the test chamber (11); The sliding sleeve (13) is axially slidable and radially limited and is fitted on the outer side of the middle part of the guide rod (12). A pair of continuous racks (9) are fixedly connected to its front and rear parts in a symmetrical manner. A strip-shaped groove is opened on the left side panel of the test box (11) corresponding to the sliding sleeve (13). The grip (10) is located on the outside of the test box (11) and is fixedly connected to the lower end of the slide sleeve (13) by a cross link (22) passing through the slide groove; Two rotating shafts (14) are located inside the conduction cavity (19) and are symmetrically distributed on the outside of a pair of continuous racks (9), and their two ends are rotatably connected to the left and right side panels of the test chamber (11), respectively. Two gears (6) are fixedly mounted on the ends of two rotating shafts (14) respectively, and mesh with a pair of continuous racks (9); The two first connecting rods (15) are located on the inner front and inner rear sides of the conduction cavity (19) respectively, and are symmetrically distributed above the two rotating shafts (14). Their two ends are rotatably connected to the left and right side panels of the test box (11) respectively. Two second connecting rods (16) are located on the outer front and outer rear of the conduction cavity (19), and are symmetrically distributed on the outer side above the two first connecting rods (15), and their two ends are rotatably connected to the left and right box plates of the test box (11), respectively. Two bearing cavities (20) are evenly divided into multiple pairs of accommodating spaces (1) along their length; each accommodating space (1) extends vertically, and four protective pads (2) are provided around its top and bottom. The four protective pads (2) around its top are located below the first connecting rod (15) and the second connecting rod (16). The two protective pads (2) at the top of two adjacent accommodating spaces (1) are an integral structure, and its outer end is fixedly connected to the outer box plate of the test chamber (11) through the first connecting plate (23), and its inner end is fixedly connected to the partition plate (17) through the second connecting plate (24). The protective pad (2) on the inner side of the top of each accommodating space (1) is fixedly connected to the partition plate (17), and the remaining outer protective pads (2) are fixedly connected to the test chamber (11). A hollow area (3) is provided between the two protective pads (2) on the inner side of each accommodating space (1) and between the two protective pads (2) on the outer side. The conductive cavity (19) is uniformly provided with multiple test units along its length, and the multiple test units correspond to the arrangement of multiple pairs of accommodating spaces (1); each test unit consists of two straight connecting rods (7), two small metal balls (8), two first fixed pulleys (4), two second fixed pulleys (21), a cable connecting rod (18), and two cable retainers (5). The two straight connecting rods (7) are of the same length and are arranged symmetrically front and back. Their upper ends are fixedly connected to two rotating shafts (14) respectively. The two small metal balls (8) are fixedly connected to the lower ends of the two straight connecting rods (7) respectively, and can enter the hollow area during the swing of the straight connecting rods (7). 3) Two first fixed pulleys (4) are located on the right side of two straight connecting rods (7) and are arranged symmetrically front and back, and are respectively connected to two first connecting rods (15). Two second fixed pulleys (21) are located on the outside of the two first fixed pulleys (4) and are arranged symmetrically front and back, and are respectively connected to two second connecting rods (16). The cable connecting rod (18) is located above the two first connecting rods (15), and its two ends are respectively fixedly connected to the left and right box plates of the test box (11). Two cable retainers (5) are located between the two first fixed pulleys (4) and are fixedly connected to the cable connecting rod (18) symmetrically front and back.

2. The universal anti-tipping testing device for downhole seismic sensors according to claim 1, characterized in that, The straight connecting rod (7) is made of tough metal material. The upper end of the straight connecting rod (7) is connected to the rotating shaft (14) through an angle-adjustable connecting rod. The angle-adjustable connecting rod makes the connection angle of the straight connecting rod (7) relative to the rotating shaft (14) adjustable.

3. A universal anti-tipping testing device for downhole seismic sensors according to claim 1 or 2, characterized in that, Each containment space (1) has four protective pads around the top and bottom, and (2) the adjacent sides have arc-shaped grooves.

4. The universal anti-tipping testing device for downhole seismic sensors according to claim 3, characterized in that, The number of the accommodating spaces (1) is 16 pairs.

5. A universal anti-tipping testing device for downhole seismic sensors according to claim 4, characterized in that, The first fixed pulley (4) and the second fixed pulley (21) both have annular grooves, the size of which is adapted to the size of the cable (26) connected to the vibration sensor (25) to be tested.

6. The universal anti-tipping testing device for downhole seismic sensors according to claim 5, characterized in that, The guide rod (12) has an upper limit ring (27) and a lower limit ring (28) fixedly fitted above and below the sliding sleeve (13), respectively. The upper limit ring (27) and the lower limit ring (28) are used to limit the sliding stroke of the sliding sleeve (13) on the guide rod (12).

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