A wellbore flushing and scale removal device for use in oil production wells

Abstract

The utility model belongs to the field of petroleum collection technology relates to a well pipe flushing and descaling device for oil production well, include: drainage tank, annular air bag, stroke frame, sliding block, rotating ring, high pressure spray head, the lower fixed plate of stroke frame connects drainage tank, sliding block slides up and down along the screw rod of stroke frame, the inner ring of rotating ring rotatably connects the outer cylindrical surface of sliding block, the outer ring of rotating ring is equipped with the scraper that projects outward along the radial, high pressure spray head is detachably connected on sliding block, the utility model discloses through the high pressure water flow and scraper rotary scraping of high pressure spray head injection removes the deposit scale layer, has realized the removal of deposit scale layer on the wellbore or oil pipe inner hole wall, the utility model discloses can adopt the rope to hang to the deep place in wellbore or oil pipe and carry out the cleaning and descaling, will not because the depth of wellbore or oil pipe and influence the cleaning effect and descaling efficiency.

Description

Technical Field

[0001] This utility model belongs to the field of petroleum extraction technology, specifically relating to a well pipe flushing and descaling device for oil wells. Background Technology

[0002] Wellbore flushing and descaling in oil wells refers to a specialized operation performed to remove scale deposits that accumulate in the wellbore, casing, tubing, and other components due to long-term production. These scale deposits are typically composed mainly of minerals such as calcium and magnesium and can severely impact normal oil well production. Current wellbore flushing and descaling operations are broadly categorized into physical cleaning and chemical cleaning methods, with a combination of methods sometimes employed depending on the situation. Current flushing methods typically utilize well-washing trucks and high-pressure pumps for scale removal.

[0003] However, the existing flushing and descaling methods using well washing trucks and high-pressure pumps are insufficient to meet the current needs of wellbore flushing and descaling for deep wells or tubing.

[0004] Therefore, a flushing and descaling device that can effectively clean deep within wellbores or oil pipes is needed to solve the above-mentioned technical problems. Utility Model Content

[0005] The technical solution adopted by this utility model to solve the technical problem is: a well pipe flushing and descaling device for oil wells, including: a drainage trough, an annular airbag, a stroke frame, a slider, a rotating ring, and a high-pressure nozzle; the drainage trough is an annular groove with an open top, the annular airbag is cylindrical, the annular airbag surrounds the outer cylindrical surface of the drainage trough, and the upper part of the annular airbag is provided with an inflation / deflation port.

[0006] The travel frame includes: an upper fixed plate, a lower fixed plate, a middle cylinder, a lead screw, and a guide rod. The middle cylinder is long and cylindrical, with its upper and lower ends connected to the upper and lower fixed plates, respectively. The inner cylinder of the middle cylinder passes through the upper surface of the upper fixed plate and the lower surface of the lower fixed plate. The two ends of the lead screw are connected to the upper and lower fixed plates by rotating shafts, respectively. The upper fixed plate is equipped with a first motor to drive the lead screw to rotate. The two ends of the guide rod are connected to the upper and lower fixed plates, respectively. The rotation shafts of the lead screw and guide rod are vertical. The lower fixed plate is connected to a drainage groove.

[0007] The slider is annular, and its annular inner hole is fitted around the outer cylinder with clearance. The slider is equipped with a lead screw and nut threaded connection to the lead screw, and a smooth hole sliding connection to the smooth rod. The rotating ring is annular, and its inner ring is rotatably connected to the outer cylindrical surface of the slider. The outer ring of the rotating ring is equipped with a scraper extending radially outward. The upper part of the rotating ring is equipped with an annular gear ring. The slider is equipped with a second motor, and the second motor drives the gear to mesh with the gear ring. The gear ring, rotating ring, drainage groove, annular airbag and the outer circumference of the slider are on the same rotation axis.

[0008] The high-pressure nozzle is detachably connected to the slider. There are multiple high-pressure nozzles. The spray direction of the high-pressure nozzle is towards the inner wall of the wellbore or tubing. The water inlet of the high-pressure nozzle is connected to the high-pressure water source through the water inlet pipe. The middle cylinder is equipped with a drain pipe and an air pipe. The water inlet of the drain pipe is located in the drain trough, and the outlet of the drain pipe is connected to the drain pump. One end of the air pipe is connected to the air filling and emptying port, and the other end of the air pipe is connected to the air pump.

[0009] Preferably, the drainage trough is equipped with a stirring paddle, and the middle cylinder is equipped with a third motor, which drives the stirring paddle to rotate and stir.

[0010] More preferably, the rotation axis of the agitator is vertical and the edge of the agitator is sharp.

[0011] Preferably, the optical bar and / or lead screw are provided with limit blocks at both ends, and the limit blocks are electrically connected to the first motor.

[0012] Preferably, the upper fixing plate has a lifting ring on its upper surface.

[0013] Preferably, the lower fixing plate is disc-shaped, and the edge of the disc is connected to the upper edge of the drainage channel through multiple ribs.

[0014] Preferably, the rotating ring is rotatably connected to the slider via a bearing.

[0015] Preferably, the scraper head and the scraper shank are divided into two sections, and the scraper head and the scraper shank are elastically connected by a spring.

[0016] Even better, the extension length of the spring is adjustable.

[0017] Preferably, there are 1 to 2 lead screws and 2 to 4 guide rods, which are evenly distributed around the middle cylinder.

[0018] The beneficial effects of this utility model are: 1. This utility model removes deposited scale layers from the inner wall of wellbore or oil pipe by using high-pressure water jets from a high-pressure nozzle and rotating scrapers, either individually or in combination. This utility model can be hoisted with ropes to the depth of the wellbore or oil pipe for cleaning and descaling, and the cleaning effect and descaling efficiency will not be affected by the depth of the wellbore or oil pipe.

[0019] 2. This utility model achieves timely discharge of flushing water and deposited scale by setting a drainage trough below the high-pressure nozzle and scraper, setting an annular airbag outside the drainage trough, and setting a drainage pipe inside the drainage trough. It also effectively prevents flushing water and deposited scale from falling into the wellbore or deep into the oil tubing and causing secondary pollution to the oil well.

[0020] 3. This utility model, by setting an agitator in the drainage tank, enables the large-diameter deposited scale layer generated during cleaning and descaling to be cut and broken up and discharged quickly and in a timely manner, thus avoiding the impact on the efficiency and progress of cleaning and descaling due to the large diameter of the deposited scale layer. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the working state of a well pipe flushing and descaling device for oil wells according to this utility model; Figure 2 This is a utility model Figure 1 AA view; Figure 3 This is a utility model Figure 1 BB view; Figure 4 This is a utility model Figure 1 CC view; Figure 5 This is a utility model Figure 1 A magnified view of the D-axis; Figure 6 This is a utility model Figure 4 A magnified view of the E-axis; Figure 7 This is a schematic diagram of the device structure of this utility model; Figure 8 This is an exploded view of the components of this utility model.

[0022] In the diagram: 1. Drainage trough; 2. Annular airbag; 3. Stroke frame; 4. Slider; 5. Rotary ring; 6. High-pressure nozzle; 11. Drainage pipe; 12. Agitator; 13. Third motor; 14. Rib plate; 21. Air inlet / outlet; 22. Air pipe; 31. Upper fixing plate; 32. Lower fixing plate; 33. Middle cylinder; 34. Lead screw; 35. Smooth rod; 36. First motor; 37. Limit block; 38. Lifting ring; 41. Lead screw nut; 42. Smooth hole; 51. Scraper; 52. Gear ring; 53. Second motor; 54. Gear; 55. Bearing; 56. Spring; 61. Water inlet pipe. Detailed Implementation

[0023] The relevant technologies of this utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0024] refer to Figures 1-8A wellbore flushing and descaling device for oil wells includes: a drainage trough 1, an annular airbag 2, a travel frame 3, a slider 4, a rotating ring 5, and a high-pressure nozzle 6; the drainage trough 1 is an annular groove with an open top, and the annular airbag 2 is cylindrical, surrounding the cylindrical surface of the drainage trough 1, with an inflation / deflation port 21 at the top; the outer diameter of the cylinder of the drainage trough 1 is smaller than the inner diameter of the wellbore or tubing to be cleaned, and the annular airbag 2 expands radially after inflation to seal the annular gap between the outer circumferential wall of the drainage trough 1 and the inner hole of the wellbore or tubing to prevent flushing fluid and detached deposited scale from falling into the depth of the wellbore or tubing.

[0025] The travel frame 3 includes: an upper fixed plate 31, a lower fixed plate 32, a middle cylinder 33, a lead screw 34, and a guide rod 35. The middle cylinder 33 is long and cylindrical. The upper and lower ends of the middle cylinder 33 are respectively connected to the upper fixed plate 31 and the lower fixed plate 32. The inner cylinder of the middle cylinder 33 passes through the upper surface of the upper fixed plate 31 and the lower surface of the lower fixed plate 32. The two ends of the lead screw 34 are respectively connected to the upper fixed plate 31 and the lower fixed plate 32. The upper fixed plate 31 is equipped with a first motor 36 to drive the lead screw 34 to rotate. The two ends of the guide rod 35 are respectively connected to the upper fixed plate 31 and the lower fixed plate 32. The rotation axes of the lead screw 34 and the guide rod 35 are vertical. The lower fixed plate 32 is connected to the drainage groove 1.

[0026] The slider 4 is annular, and its annular inner hole is fitted around the middle cylinder 33 with clearance. The slider 4 is provided with a lead screw nut 41 threadedly connected to the lead screw 34, and the slider 4 is provided with a smooth hole 42 slidably connected to the smooth rod 35. When the lead screw 34 rotates, it drives the slider 4 to slide up and down along the vertical direction of the smooth rod 35 and the lead screw 34. The rotating ring 5 is annular, and its inner ring is rotatably connected to the outer cylindrical surface of the slider 4. The outer ring of the rotating ring 5 is provided with a scraper 51 extending radially outward. The upper part of the rotating ring 5 is provided with an annular gear ring 52. The slider 4 is provided with a second motor 53, which drives a gear 54 to mesh with the gear ring 52. The gear ring 52, the rotating ring 5, the drainage groove 1, the annular airbag 2 and the outer circumference of the slider 4 are on the same rotation axis. When the second motor 53 drives the gear ring 52 through the meshing of the gear 54, the rotating ring 5 rotates around the slider 4, thereby driving the scraper 51 to rotate horizontally and scrape away the deposited scale layer on the inner wall of the well barrel or oil pipe.

[0027] The high-pressure nozzle 6 is detachably connected to the slider 4. Multiple high-pressure nozzles 6 are provided. The spray direction of the high-pressure nozzle 6 is towards the inner wall of the wellbore or oil pipe. The water inlet of the high-pressure nozzle 6 is connected to the high-pressure water source through the water inlet pipe 61. The high-pressure water flow sprayed by the high-pressure nozzle 6 can remove the deposited scale layer on the inner wall of the wellbore or oil pipe through pressure.

[0028] The middle cylinder 33 is equipped with a drain pipe 11 and an air pipe 22. The inlet of the drain pipe 11 is located in the drain trough 1, and the outlet of the drain pipe 11 is connected to the drain pump. One end of the air pipe 22 is connected to the air filling and emptying port 21, and the other end of the air pipe 22 is connected to the air pump. The drain pipe 11 is used to remove the flushing water accumulated in the drain trough 1 and the deposit scale carried in the flushing water. The air pump inflates and deflates the annular airbag 2 through the air pipe 22 and the air filling and emptying port 21 to seal the annular gap between the outer circumferential wall of the drain trough 1 and the inner hole of the well barrel or oil pipe.

[0029] Furthermore, the drainage tank 1 is equipped with a stirring paddle 12, and the middle cylinder 33 is equipped with a third motor 13. The third motor 13 drives the stirring paddle 12 to rotate and stir. The stirring paddle 12 stirs the flushing water in the drainage tank 1 and the deposited scale carried in the flushing water, so that the drain pipe 11 can quickly and timely discharge the flushing water and the deposited scale, and prevent the deposited scale from settling and accumulating and affecting the discharge.

[0030] Furthermore, the rotating shaft of the agitator 12 is vertical, and the edge of the agitator 12 is sharp. When the deposit scale carried in the flushing water has a large diameter, the agitator 12 rotates at high speed and cuts and breaks the large diameter deposit scale through the edge sharpness, so that the drain pipe 11 can quickly and timely discharge it.

[0031] Furthermore, the optical bar 35 and / or lead screw 34 are provided with limit blocks 37 at both ends, and the limit blocks 37 are electrically connected to the first motor 36. The limit blocks 37 are used to limit the up and down stroke of the slider 4, and can also be linked with the first motor 36 to realize that the motor turns after the slider 4 is in place, thereby driving the slider 4 to slide up and down in the vertical direction.

[0032] Furthermore, the upper surface of the upper fixing plate 31 is provided with a lifting ring 38, which is used to move the entire flushing and descaling device up and down.

[0033] Furthermore, the lower fixing plate 32 is disc-shaped, and the edge of the disc of the lower fixing plate 32 is radially connected to the upper edge of the drainage trough 1 through multiple ribs 14. A large hollow channel is left between the lower fixing plate 32 fixed by the ribs 14 and the upper opening of the drainage trough 1, which is conducive to the flow of flushing water and the deposited scale layer carried in the flushing water from the well barrel or oil pipe into the drainage trough 1.

[0034] Furthermore, the rotating ring 5 is rotatably connected to the slider 4 via a bearing 55. The inner shell of the bearing 55 is fitted onto the outer ring of the slider 4, and the outer shell of the bearing 55 is embedded in the inner ring of the rotating ring 5. At least two bearings are provided along the axial direction to make the rotation of the rotating ring 5 more stable.

[0035] Furthermore, the scraper 51 has a blade head and a shank divided into two sections, and the blade head and shank of the scraper 51 are elastically connected by a spring 56. The elastic connection between the blade head and the shank makes the radial extension of the scraper 51 adjustable, and the scraper 51 is more advantageous when horizontally rotating to scrape and remove the deposited scale layer on the inner wall of the well barrel or tubing. For well barrels or tubing with thick deposited scale layers, it can be scraped and removed in multiple sequential steps.

[0036] Furthermore, the extension length of the spring 56 is adjustable, which allows the well casing flushing and descaling device to be applicable to wellbore or tubing inner bores of various diameters.

[0037] Furthermore, there are 1 to 2 lead screws 34 and 2 to 4 optical rods 35. The lead screws 34 and optical rods 35 are evenly distributed around the middle cylinder 33. The multiple optical rods 35 and lead screws 34 make the sliding block 4 slide more smoothly up and down. The rotation of the rotating ring 5 drives the scraper 51 to rotate horizontally to scrape and remove the deposited scale layer on the inner wall of the well barrel or oil pipe. Example

[0038] In the specific implementation in the field environment, the gas in the annular airbag 2 is first discharged, causing the annular airbag 2 to contract radially. Then, the well pipe flushing and descaling device is hoisted into the well barrel or oil pipe by means of a rope suspended at the lifting ring 38. When it reaches the position to be flushed, the rope is fixed to ensure the height of the well pipe flushing and descaling device, and then air is inflated into the annular airbag 2, causing the annular airbag 2 to expand radially and seal the annular gap between the outer circumference of the drainage groove 1 and the inner wall of the well barrel or oil pipe.

[0039] Subsequently, high-pressure water is supplied to the high-pressure nozzle 6 through the water inlet pipe 61 at the wellbore or tubing inlet. The high-pressure water jet from the high-pressure nozzle 6 removes the deposited scale layer on the inner wall of the wellbore or tubing under high pressure. The first motor 36 and the second motor 53 are started, driving the scraper 51 to rotate in the horizontal plane while sliding up and down along the depth direction of the wellbore or tubing. This causes the scraper 51 to reciprocate within the length range of the lead screw 34, scraping and removing the deposited scale layer on the inner wall of the wellbore or tubing.

[0040] The high-pressure water jet from the high-pressure nozzle 6 washes away the scale deposits on the inner wall of the wellbore or tubing, and the scale deposits are scraped and removed by the horizontal rotation of the scraper 51. After mixing with the water, the scale flows from the inner wall into the drainage trough 1. At this time, the third motor 13 starts and drives the agitator 12 to rotate at high speed. The agitator 12 cuts and breaks up the large-diameter scale deposits through the sharp edge of the agitator 12, so that the drainage pipe 11 can quickly and timely discharge the scale.

[0041] After the scale deposits within this section are removed, the operator releases the gas in the annular airbag 2 through the air pipe 22 and the air inlet 21, causing the annular airbag 2 to contract radially. Then, the well casing flushing and descaling device is hoisted to the next flushing position through the rope at the well casing or tubing opening. The above steps are repeated until the entire well casing or tubing is cleaned.

[0042] In actual operation, due to the complex internal environment of the wellbore or tubing, there may be deposits of varying hardness and thickness. The scraper 51 of this device is designed with an elastic connection, which can automatically adjust the scraping force according to the actual condition of the deposits. For harder deposits, the blade of scraper 51 will compress the spring 56 due to greater resistance, thereby increasing the scraping force. For softer deposits, the spring 56 remains in its natural state, and scraper 51 scrapes with less force. This effectively removes the deposits while avoiding unnecessary damage to the inner wall of the wellbore or tubing.

[0043] Meanwhile, the design of the high-pressure nozzles 6 also takes into account the cleaning needs of different scale layers. Multiple high-pressure nozzles 6 are evenly distributed on the slider 4, and the spray direction is adjustable, which can adjust the spray angle and pressure according to the distribution of scale layers to ensure that every scale layer is thoroughly flushed. In addition, the high-pressure nozzles 6 adopt a detachable connection method, which facilitates quick replacement when damaged or when different specifications need to be replaced, improving the maintenance efficiency and flexibility of the device.

[0044] In terms of drainage, the combination of drainage pipe 11 and drainage pump ensures that flushing water and deposited scale can be discharged from the wellbore or tubing in a timely manner, avoiding secondary pollution. At the same time, the agitator 12 in the drainage tank 1 cuts and breaks up large-diameter deposited scale through high-speed rotation, further improving the smoothness and efficiency of drainage.

[0045] The entire device, through the coordinated operation of components such as the stroke frame 3, slider 4, and rotating ring 5, achieves vertical movement and horizontal rotational scraping within the wellbore or tubing, as well as the jetting of high-pressure water and the discharge of flushing water, forming a complete cleaning and descaling system. This system is suitable not only for wellbores or tubing of different depths and diameters, but also allows for adjustments to the cleaning strategy based on the actual condition of the scale layer, ensuring cleaning effectiveness and efficiency.

[0046] Furthermore, the device has also been designed with safety and reliability in mind. The linkage between the limit block 37 on the travel frame 3 and the first motor 36 ensures that the slider 4 slides up and down within the set travel range, preventing equipment damage or safety accidents caused by the slider 4 exceeding its travel range. At the same time, the inflation and deflation design of the annular airbag 2 allows the device to be flexibly adjusted in size when entering and exiting the wellbore or tubing to adapt to the needs of different pipe diameters. It can also effectively seal the gap between the drainage groove 1 and the inner wall of the wellbore or tubing, preventing flushing water and deposited scale from falling deep into the wellbore or tubing and causing secondary pollution.

[0047] In practical applications, this device also demonstrates excellent operability and maintainability. Operators can easily lower the device into the wellbore or tubing for cleaning and descaling operations using simple rope hoisting and inflation / deflation procedures. Furthermore, all components of the device are modularly designed, facilitating disassembly and replacement, thus reducing maintenance costs and time.

[0048] In summary, this wellbore flushing and descaling device for oil wells, through its unique design and functionality, effectively removes deposited scale from the inner walls of wellbores or tubing. The device not only features dual cleaning functions—high-pressure water jetting and rotary scraping—but is also equipped with auxiliary components such as a drainage channel, annular airbag, and agitator, ensuring a smooth and efficient cleaning process. Furthermore, the device excels in safety, reliability, and operability, providing an efficient and practical solution for cleaning and descaling operations in oil wells.

[0049] It should be emphasized that the above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present utility model shall still fall within the scope of the technical solution of the present utility model.

Claims

1. A well casing flushing and descaling device for oil wells, characterized in that, include: Drainage channel (1), annular airbag (2), stroke frame (3), slider (4), rotating ring (5), high-pressure nozzle (6); The drainage trough (1) is a circular groove with an open top, and the annular airbag (2) is cylindrical. The annular airbag (2) surrounds the outer cylindrical surface of the drainage trough (1), and the annular airbag (2) is provided with an inflation / deflation port (21) at the top. The travel frame (3) includes: an upper fixed plate (31), a lower fixed plate (32), a middle cylinder (33), a lead screw (34), and a guide rod (35). The middle cylinder (33) is long and cylindrical. The upper and lower ends of the middle cylinder (33) are connected to the upper fixed plate (31) and the lower fixed plate (32) respectively. The inner cylinder of the middle cylinder (33) passes through the upper surface of the upper fixed plate (31) and the lower surface of the lower fixed plate (32). The two ends of the lead screw (34) are connected to the upper fixed plate (31) and the lower fixed plate (32) respectively. The upper fixed plate (31) is equipped with a first motor (36) to drive the lead screw (34) to rotate. The two ends of the guide rod (35) are connected to the upper fixed plate (31) and the lower fixed plate (32) respectively. The rotation axes of the lead screw (34) and the guide rod (35) are vertical. The lower fixed plate (32) is connected to the drainage trough (1). The slider (4) is annular, and the annular inner hole of the slider (4) is fitted with a clearance fit outside the middle cylinder (33). The slider (4) is provided with a screw nut (41) threadedly connected to the screw (34), and the slider (4) is provided with a light hole (42) slidingly connected to the light rod (35). The rotating ring (5) is annular, and the inner ring of the rotating ring (5) is rotatably connected to the outer cylindrical surface of the slider (4). The outer ring of the rotating ring (5) is provided with a scraper (51) extending radially outward. The upper part of the rotating ring (5) is provided with an annular toothed ring (52). The slider (4) is provided with a second motor (53). The second motor (53) drives a gear (54) to mesh with the toothed ring (52). The toothed ring (52), the rotating ring (5), the drainage groove (1), the annular airbag (2) and the outer circumference of the slider (4) are on the same rotation axis. The high-pressure nozzle (6) is detachably connected to the slider (4). Multiple high-pressure nozzles (6) are provided. The spray direction of the high-pressure nozzle (6) is towards the inner wall of the well barrel or oil pipe. The water inlet of the high-pressure nozzle (6) is connected to the high-pressure water source through the water inlet pipe (61). The middle cylinder (33) is provided with a drain pipe (11) and an air pipe (22). The inlet of the drain pipe (11) is located in the drain trough (1), and the outlet of the drain pipe (11) is connected to the drain pump. One end of the air pipe (22) is connected to the air filling and discharging port (21), and the other end of the air pipe (22) is connected to the air pump. The drainage trough (1) is equipped with a stirring paddle (12), and the middle cylinder (33) is equipped with a third motor (13). The third motor (13) drives the stirring paddle (12) to rotate and stir. The lead screw (34) is provided with 1 to 2 screws, and the optical rod (35) is provided with 2 to 4 screws. The lead screw (34) and the optical rod (35) are evenly distributed around the middle cylinder (33).

2. The well casing flushing and descaling device for oil wells according to claim 1, characterized in that, The rotating axis of the stirring paddle (12) is vertical, and the edge of the stirring paddle (12) is sharp.

3. The well casing flushing and descaling device for oil wells according to claim 1, characterized in that, The optical bar (35) and / or lead screw (34) are provided with limit blocks (37) at both ends, and the limit blocks (37) are electrically connected to the first motor (36).

4. The well casing flushing and descaling device for oil wells according to claim 1, characterized in that, The upper surface of the upper fixing plate (31) is provided with a lifting ring (38).

5. A well casing flushing and descaling device for oil wells according to claim 1, characterized in that, The lower fixing plate (32) is disc-shaped, and the edge of the disc of the lower fixing plate (32) is connected to the upper edge of the drainage groove (1) through multiple ribs (14).

6. The well casing flushing and descaling device for oil wells according to claim 1, characterized in that, The rotating ring (5) is rotatably connected to the slider (4) via the bearing (55).

7. The well casing flushing and descaling device for oil wells according to claim 1, characterized in that, The scraper (51) has a blade head and a handle divided into two sections, and the blade head and handle are elastically connected by a spring (56).

8. A well casing flushing and descaling device for oil wells according to claim 7, characterized in that, The extension length of the spring (56) is adjustable.

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