JP5530298B2 - Landing gear - Google Patents

Description

  The technology disclosed herein relates to an aircraft landing gear, and more particularly, to an landing gear including a buffer post including an orifice and a metering pin that changes an orifice cross-sectional area.

  For example, Patent Document 1 discloses an aircraft landing gear having a buffer strut that includes an outer cylinder and an inner cylinder that are coaxially arranged to move relative to each other in the cylinder axis direction. This buffer strut contains hydraulic oil and nitrogen gas in an internal space sealed by the outer cylinder and the inner cylinder and incorporates an orifice. For example, when the buffer strut contracts during landing of an aircraft, Buffering is performed by the compression resistance of the gas and the orifice resistance when the hydraulic oil passes through the orifice hole. In addition, in order to make the damping characteristics of the buffer struts change so that the damping amount changes with respect to the amount of expansion and contraction, this landing gear has a built-in metering pin that tapers from the proximal end toward the distal end. Yes. Since the metering pin relatively moves in the direction of the cylinder axis in the orifice hole along with the expansion and contraction of the buffer strut, the cross-sectional area of the orifice changes and the amount of attenuation with respect to the expansion and contraction changes.

Japanese Utility Model Publication No. 64-9900

  By the way, in the landing gear disclosed in Patent Document 1, the metering pin is fixed to the inner cylinder, and in this case, the orifice is disposed at an intermediate position in the cylinder axis direction in the internal space of the buffer strut. However, it must be fixed to the outer cylinder. For this reason, in a general landing gear, an orifice is fixed to the tip of a support tube arranged in the outer cylinder so as to extend in the cylinder axis direction. The orifice is disposed at an intermediate position in the cylinder axis direction while avoiding interference with the moving inner cylinder and the metering pin.

  Here, in the landing gear disclosed in Patent Document 1, the base end portion of the support tube is fixed to the outer cylinder outside the outer cylinder. In other words, the base end of the support tube protrudes to the outside of the outer cylinder through a through-hole formed at the closed end that closes the one end opening of the outer cylinder, and the base end that protrudes to the outside is fixed to the outer cylinder with a nut. Yes. This is because a relatively high load acts on the support tube in the direction of the cylinder axis due to the instantaneous pressure difference that occurs above and below the orifice when the aircraft is landing, etc. One reason is that you need to do that.

However, when the through-hole is formed in the outer cylinder in order to firmly fix the support tube, since the hydraulic oil and nitrogen gas are sealed inside the buffer support column as described above, the portion of the through-hole is filled with nitrogen gas. It is necessary to provide a seal to prevent leakage. Usually, as described in Patent Document 1, a configuration is adopted in which a packing such as an O-ring is inserted into a groove formed on the inner peripheral surface of the through hole. However, such a seal structure may cause leakage of nitrogen gas due to deterioration over time, for example, so that the reliability of the landing gear can be lowered. In particular, since the diameter of the through hole formed in the outer cylinder is formed to be relatively large so that the support tube can pass, the diameter of the packing increases, and the desired sealing performance can be obtained over a long period of time. It may be difficult to obtain stably.

  The technology disclosed herein has been made in view of the above points, and the purpose of the technology is to improve the sealing performance of the buffer struts in the landing gear of the aircraft and to reduce the reliability due to leakage of the enclosed gas. Is to avoid.

  The landing gear disclosed herein includes hydraulic oil in an internal space sealed by an outer cylinder whose one end is a closed end and the other end is an open end, and an inner cylinder inserted into the outer cylinder from the open end. And a buffer strut that can be expanded and contracted in the cylinder axis direction by relative movement of the outer cylinder and the inner cylinder, and an intermediate position in the cylinder axis direction in the internal space of the buffer strut, An orifice disposed on the cylinder shaft, a tip portion thereof is a mounting portion to which the orifice is attached, and a base end portion thereof is a fixing portion fixed to the closed end in the outer cylinder. A support tube disposed in the inner space extending in the cylinder axis direction, a base end side of the support tube being fixed to the inner cylinder, and extending on the cylinder axis toward the orifice; Said A metering pin that moves relative to the orifice in accordance with expansion and contraction of the buffer strut in a state of being inserted with a gap with respect to the hole of the fiss, and a fixed portion of the support tube in the closed end in the outer cylinder And a fixing mechanism for fixing to.

  Then, the fixing mechanism includes a nut that is screwed to a thread formed on the outer peripheral surface of the fixing portion of the support tube, and an inner peripheral surface of the outer cylinder in the vicinity of the closed end. A retaining ring that is fitted into a recessed groove formed over the retaining groove, and the fixing mechanism includes a nut disposed between the fixing portion and an inner peripheral surface of the outer cylinder. The support tube fixing portion is closed by the reaction force caused by applying torque in a direction away from the closing end to the nut in a state where the position of the nut is fixed by engaging with the nut. It is configured to be pressed against the end and fixed.

  According to this configuration, the fixing mechanism is fitted into a nut that engages with a screw thread formed on the outer peripheral surface of the fixing portion of the support tube and a recessed groove formed on the inner peripheral surface of the outer cylinder near the closed end. And a retaining ring fixed to the outer cylinder, and the nut and the retaining ring are engaged with each other and the position of the nut is fixed, and the nut is separated from the closed end. The support tube is configured to be pressed and fixed to the closed end of the outer cylinder by a reaction force accompanying the application of torque in the direction. In other words, the fixing mechanism is configured to fix the support tube inside the outer cylinder, and has a conventional configuration in which a through hole is formed at the end of the outer cylinder and the support tube protrudes outside the outer cylinder. Can be omitted. This makes it possible to omit the sealing structure of the outer cylinder, which can be advantageous in improving the reliability of the landing gear as well as the sealing performance of the buffer struts.

  On the other hand, with the expansion and contraction of the buffer strut, that is, with the landing and takeoff of the aircraft, a large load can act on the support tube in the direction of the cylinder axis, but the fixing mechanism is accompanied by applying torque to the nut. Due to the reaction force, the support tube fixing part is pressed against the closed end in the outer cylinder and fixed, so the support tube can be firmly fixed to the outer cylinder, acting when the buffer struts are expanded and contracted. It can resist the heavy loads that can be done.

  The fixing mechanism further includes an anti-rotation insert that protrudes and is attached to an outer peripheral surface of the fixing portion on which the thread is formed, and the insert is configured such that the nut is screwed onto the outer peripheral surface of the fixing portion. When the support tube is pressed against the closed end of the outer cylinder and fixed, the support tube may be deformed so as to crush the thread and function as a detent for the nut.

  As described above, since the fixing mechanism fixes the support tube to the outer cylinder by the reaction force accompanying the torque applied to the nut, when the nut turns, the force for fixing the support tube decreases. End up. Therefore, providing an insert for preventing the rotation of the nut is advantageous in securing the support tube to the outer cylinder stably over a long period of time.

  The landing gear different from the above is an orifice arranged on the cylinder shaft at an intermediate position in the cylinder axis direction in the internal space of the buffer strut by being fixed to the buffer strut and the inner cylinder, The base end portion serves as a fixed portion that is fixed to the closed end in the outer cylinder, and is disposed so as to extend on the cylinder shaft toward the orifice, leaving a gap with respect to the hole of the orifice. A metering pin that moves relative to the orifice in response to expansion and contraction of the buffer strut, and a fixing mechanism for fixing a fixing portion of the metering pin to the closed end in the outer cylinder And comprising.

  Thus, the fixing mechanism includes a nut screwed to a thread formed on the outer peripheral surface of the fixing portion of the metering pin, and an inner peripheral surface of the outer cylinder near the closed end. A retaining ring that fits into a recessed groove formed over the retaining groove, and the fixing mechanism includes a nut disposed between the fixing portion and an inner peripheral surface of the outer cylinder. In a state where the position of the nut is fixed by engaging with the ring, the fixing portion of the metering pin is attached to the outer cylinder by a reaction force accompanying the torque in a direction away from the closed end to the nut. It is comprised so that it may press against the closed end of and may be fixed.

  That is, in this configuration, the fixing mechanism including the nut and the retaining ring described above is employed in the configuration for fixing the metering pin to the outer cylinder, and the landing gear is eliminated by omitting the seal structure as described above. Can be improved, and the metering pin can be stably fixed to the outer cylinder.

  As described above, according to the landing gear described above, the fixing mechanism including the nut and the retaining ring can firmly fix the support tube or the metering pin to the outer cylinder inside the outer cylinder. By omitting the seal structure, the reliability of the landing gear can be improved along with the increase in the sealing performance of the buffer strut.

It is sectional drawing which shows a part of landing gear. It is a disassembled perspective view which shows the fixing mechanism of a support tube. It is a figure which shows the 1st process of the assembly | attachment procedure of a support tube. It is a figure which shows the 2nd process of the assembly | attachment procedure of a support tube. It is a figure which shows the 3rd process of the assembly | attachment procedure of a support tube. It is a figure which shows the 4th process of the assembly | attachment procedure of a support tube. It is a figure corresponding to FIG. 1 which shows a part of landing gear of another structure.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature and is not intended to limit the application or application. FIG. 1 shows a part of an aircraft landing gear 1 according to this embodiment. The landing gear 1 includes a buffer column 2 that is disposed between an aircraft body and a wheel (not shown) and supports the wheel. The buffer strut 2 includes a substantially cylindrical outer cylinder 21 and a substantially cylindrical inner cylinder 22 and is configured by being inserted into the outer cylinder 21 so that the inner cylinder 22 is coaxial. .

  More specifically, the outer cylinder 21 is a cylindrical member whose one end (upper end in FIG. 1) is a closed end 211 and whose other end (lower end outside the figure) is an open end, Although illustration is omitted, the closed end side is fixed to the aircraft body side. On the other hand, the inner cylinder 22 is a cylindrical member having one end (upper end in FIG. 1) opened and the other end (lower end outside the figure) closed, and a wheel at the lower end with respect to the horizontal axis. It is pivotally supported so that it can rotate. The inner cylinder 22 is inserted from the open end of the outer cylinder 21, and the outer cylinder 21 and the inner cylinder 22 form a sealed internal space 24 in the buffer strut 2.

  The inner cylinder 22 arranged coaxially with respect to the outer cylinder 21 is movable relative to the outer cylinder 21 fixed to the airframe in the direction of the cylinder axis X, whereby the buffer column 2 is moved in the cylinder axis X direction. It is configured to expand and contract. Since the outer cylinder 21 and the inner cylinder 22 support the aircraft body, the outer cylinder 21 and the inner cylinder 22 are formed of an extremely hard material such as ultra-high strength steel 300M.

  As illustrated in FIG. 1, a predetermined amount of hydraulic oil 31 and nitrogen gas 32 are sealed in the internal space 24 of the buffer column 2. Further, in this internal space 24, an orifice 33 for imparting resistance to the flow of the hydraulic oil 31 generated when the buffer strut 2 is expanded and contracted, and a relative movement with respect to the orifice 33 when the buffer strut 2 is expanded and contracted, the orifice is cut off. A metering pin 34 for changing the area is incorporated therein.

  The orifice 33 is a substantially disk-shaped member in which a circular orifice hole 331 having a predetermined diameter is formed in the center thereof, and is supported by the support tube 4 described later, so that the orifice 33 in the internal space 24 of the buffer strut 2 is formed. At the middle position in the cylinder axis X direction, the central axis is arranged so as to be coaxial with the cylinder axis X of the buffer strut 2.

  As shown in FIGS. 1 and 2, the support tube 4 is a hollow cylindrical member made of, for example, aluminum or an aluminum alloy, and details of the mounting structure will be described later. The outer cylinder 21 and the outer cylinder 21 are arranged so as to extend in the cylinder axis X direction. As a result, a space having an annular cross section is formed between the inner peripheral surface of the outer cylinder 21 and the outer peripheral surface of the support tube 4 so as to extend in the cylinder axis direction. The relative movement of the tube 22 is allowed.

  The support tube 4 constitutes a distal end portion thereof and an attachment portion 41 to which the orifice 33 is attached, constitutes a proximal end portion of the support tube 4, a fixing portion 42 that is fixed to the outer cylinder 21, and an attachment portion 41. And a connecting portion 43 that connects the fixing portion 42 to each other.

  The outer peripheral surface side of the mounting portion 41 has a diameter larger than that of the connecting portion 43 and is substantially the same diameter as the cylindrical hole of the inner cylinder 22, and as shown in FIG. Even in such a state, the inner cylinder 22 is inserted. In addition, an attachment recess 411 having a predetermined size is provided on the lower end surface of the attachment portion 41 so as to be recessed from the lower end surface. The orifice 33 is fitted into the mounting recess 411 from the lower end opening of the mounting portion 41 and is fixed to the mounting portion 41 by fastening means such as a bolt (not shown).

The fixing portion 42 is continuous with the end of the connecting portion 43, and has a screw portion 421 whose diameter is larger than that of the connecting portion 43, and is further enlarged in diameter than the screw portion 421 on the end portion side of the screw portion 421. The insertion portion 422 is included. Among these, the insertion portion 422 is a portion that is provided in the vicinity of the closed end 211 in the outer cylinder 21 and is inserted into the reduced diameter portion 212 whose inner diameter is relatively reduced. On the other hand, as shown in FIGS. 1 and 2, a screw thread is formed on the outer peripheral surface of the screw portion 421, and a nut 51 described later is screwed into the screw portion 421. An insertion hole 423 that is recessed in the radial direction is also formed on the outer peripheral surface of the screw portion 421 as shown in an enlarged view in FIG. The insertion hole 423 is a hole for inserting and fixing an anti-rotation insert 53 to be described later. The insertion hole 423 is arranged at an arbitrary position in the circumferential direction, and the support tube 4 is arranged in the outer cylinder in the axial direction. It is formed at a position corresponding to the position of the nut 51 when it is fixed to the 21. Note that at least one of the insertion holes 423 and the inserts 53 is sufficient, but when a plurality of insertion holes 423 are formed, it is preferable that the insertion holes 423 are evenly arranged in the circumferential direction.

  The connecting portion 43 has a hollow cylindrical shape, and a plurality of through holes 431 are arranged so as to be substantially uniform over the entire circumference and the entire length so as to communicate the inside and outside. The hydraulic oil 31 and the nitrogen gas 32 can flow inside and outside the support tube 4 through the through hole 431.

  The metering pin 34 is a rod-like member extending in the cylinder axis direction and is not shown in FIG. 1, but its base end (the lower end in FIG. 1) is at the lower end in the inner cylinder 22. In the state where it is fixed and extends on the cylinder axis X toward the orifice 33 and the buffer strut 2 is extended most, its tip is located in the orifice hole 331 as illustrated in FIG. It is configured as follows. The metering pin 34 has an outer diameter smaller than that of the orifice hole 331 and is not clearly shown in FIG. 1, but is formed so as to gradually expand from the tip (upper end in FIG. 1) toward the base end. ing.

  Then, as shown in FIG. 1, when the buffer strut 2 is contracted from the state where the buffer strut 2 is most extended, the inner cylinder 22 has an annular cross section between the outer cylinder 21 and the support tube 4. While the relative movement in the cylinder axis X direction in the space, the metering pin 34 relatively moves in the cylinder axis direction in the support tube 4, and accordingly, the metering pin 34 and the orifice 33 are in the cylinder. Relative movement is made in the direction of the axis X. Therefore, for example, when the buffer strut 2 contracts due to the landing of the aircraft, the nitrogen gas 32 is compressed as the inner cylinder 22 enters the outer cylinder 21, and the hydraulic oil 31 flows into the orifice hole 331 and the metering pin 34. Flows through the gap to the outer cylinder 21 side. Thus, buffering is performed by the compression resistance and the orifice resistance of the nitrogen gas 32. At this time, since the outer diameter of the metering pin 34 gradually increases from the distal end to the proximal end, the gap between the orifice hole 331 and the metering pin 34 gradually decreases. That is, the damping characteristic of the buffer strut 2 is set such that the orifice resistance increases as the expansion amount of the buffer strut 2 per fixed time decreases (in other words, the contraction amount increases).

  The most characteristic point of the buffer strut 2 is that the support tube 4 is fixed to a closed end 211 inside the outer cylinder 21, and the base end portion of the support tube 4 is outside through a through hole formed in the outer cylinder. The fixing structure of the support tube 4 is different from that of the conventional buffer strut protruding outside the cylinder. That is, a through hole through which the support tube 4 passes is not formed in the outer cylinder 21, and a seal structure associated with the mounting and fixing of the support tube 4 is omitted.

  Specifically, the fixing mechanism 5 for fixing the fixing portion 42 of the support tube 4 to the outer cylinder 21 includes a nut 51, a retaining ring 52, and an insert 53, as shown in FIG. It is configured to include.

  As shown in FIGS. 1 to 3, the nut 51 is a member that is screwed into the fixing portion 42 (screw portion 421) of the support tube 4 formed with a screw thread, and the screw thread is formed on the inner peripheral surface thereof. It has an annular shape. The nut 51 may be made of, for example, stainless steel or iron. One end portion of the nut 51 in the thickness direction, in other words, the end portion that becomes the closed end 211 side of the outer cylinder 21 when the nut 51 is attached to the support tube 4, extends in the radial direction over the entire circumference in the circumferential direction. This portion protrudes outward, and this portion constitutes an engaging edge 511 of the nut 51. Although details will be described later, the engaging edge portion 511 is a portion that engages with the retaining ring 52 when the support tube 4 is attached and fixed.

  Further, the nut 51 is formed with four through holes 512 penetrating in the thickness direction (vertical direction in FIG. 1) at equal intervals in the circumferential direction, and these through holes turn the nut 51. In addition, a jig hole 512 with which the tip of a jig not shown is engaged. Here, a through hole is formed in the nut 51 as the jig hole 512, but the shape is not particularly limited as long as the jig can be engaged and turn the nut 51. A groove (slit) may be formed on the other end surface of the nut 51 (the surface opposite to the engagement edge 511). Further, the number of jig holes 512 is not limited to four.

  The retaining ring 52 is an annular shape having a circular cross section here, and has a shape like a so-called C ring by providing a cut at one location. As shown in FIGS. 2 and 4, the retaining ring 52 is formed on the inner peripheral surface near the closed end 211 of the outer cylinder 21 at a position away from the reduced diameter portion 212 by a predetermined distance in the cylinder axis direction. This ring is fitted into the recessed groove 213 and has a diameter slightly larger than the inner diameter of the outer cylinder 21. As clearly shown in FIG. 4, the recessed groove 213 is recessed from the inner peripheral surface of the outer cylinder 21 at an axial position opposite to the threaded portion 421 when the support tube 4 is disposed in the outer cylinder 21. At the same time, it extends over the entire circumference. When the retaining ring 52 is attached to the recessed groove 213, the retaining ring 52 is inserted into the outer cylinder 21 in a state where the diameter of the C-ring-shaped retaining ring 52 is reduced, and the recessed ring 213 is positioned at the position of the recessed groove 213. By opening the shortened retaining ring 52, the retaining ring 52 is fitted into the recessed groove 213 and fixed by an elastic restoring force. As shown in FIG. 5, the retaining ring 52 fitted into the recessed groove 213 protrudes from the inner peripheral surface of the outer cylinder 21.

  Although the insert 53 will be described in detail later, when the nut 51 is screwed into the threaded portion 421, the portion protruding from the threaded portion 421 is shaved and a part of the thread of the threaded portion 421 is crushed. It is a member that functions as a detent. As shown in FIGS. 2 and 3, the insert 53 is a substantially cylindrical piece, and may be made of a material softer than at least a stainless steel or iron nut, for example, a synthetic resin such as nylon. When the support tube 4 is attached, the insert 53 is inserted into the insertion hole 423 formed in the threaded portion 421, so that the insert 53 is arranged radially from the outer peripheral surface of the threaded portion 421 as shown in FIG. It protrudes outward.

  Next, a procedure for assembling the support tube 4 by the fixing mechanism 5 configured as described above will be described with reference to FIGS. As shown in FIG. 3, as a first step, a nut 51 is screwed into the threaded portion 421 of the support tube 4. The nut 51 is externally inserted into the support tube 4 from the side of the mounting portion 41 (the lower side in FIG. 3) so that the engagement edge portion 511 faces the fixing portion 42 of the support tube 4. Then, the nut 51 is screwed into the screw portion 421. At this time, the nut 51 is screwed at least to a position closer to the end portion side than the insertion hole 423 of the insert 53 (see an arrow of a one-dot chain line in FIG. 3). After the nut 51 is screwed in, the insert 53 is inserted into the insertion hole 423, and the insert 53 is attached to the screw portion 421 (see the one-dot chain line arrow in FIG. 3).

  Next, the support tube 4 to which the nut 51 and the insert 53 are attached is inserted into the outer cylinder 21 as shown in FIG. 4, and the insertion portion 422 at the base end thereof is inserted into the reduced diameter portion 212 of the outer cylinder 21. (Second step). At this time, the nut 51 is positioned closer to the closed end 211 than the recessed groove 213 provided in the outer cylinder 21.

  Then, as a third step, as described above, the retaining ring 52 is put into the outer cylinder 21 with the diameter reduced and deformed, and the shortened retaining ring 52 is opened at the position of the recessed groove 213. Thus, the retaining ring 52 is fitted into the recessed groove 213 by the elastic restoring force (see FIG. 5). Thus, the retaining ring 52 fitted in the recessed groove 213 protrudes from the inner peripheral surface of the outer cylinder 21.

  In this state, although not shown in the figure, a jig is inserted from the open end of the outer cylinder 21 and its tip is engaged with the jig hole 512 of the nut 51, and the nut 51 is screwed using the jig. Rotate in a direction away from the part 421. As a result, the nut 51 moves downwardly away from the closed end 211 as shown by the one-dot chain line arrow in FIG. 6, and the engaging edge 511 and the retaining ring 52 are engaged with each other. . As a result, the nut 51 is restricted from moving further downward. On the other hand, when the nut 51 continues to be turned, the reaction force of the torque applied to the nut 51 acts upward on the support tube 4. The support tube 4 comes to be pressed against the closed end 211 of the outer cylinder 21. Thus, the fixing mechanism 5 firmly fixes the fixing portion 42 of the support tube 4 to the closed end 211 in the outer cylinder 21 (fourth step).

  Further, when the nut 51 is turned away from the closed end 211, the synthetic resin insert 53 is scraped by the screw thread of the nut 51 and the screw thread of the screw part 421 is crushed. Thus, after the support tube 4 is fixed to the outer cylinder 21, the insert 53 functions to prevent the nut 51 from rotating.

  Adopting such a fixing mechanism 5 eliminates the need to form a support tube mounting through hole in the outer cylinder 21 as described above, and a seal structure that is essential when the through hole is formed. Can be omitted. As a result, leakage of the nitrogen gas 32 through such a sealing structure cannot occur, so that the sealing performance of the buffer strut 2 is enhanced and the reliability of the landing gear 1 is enhanced. In addition, when the seal structure is provided, the inner peripheral surface of the through hole may be subjected to a plating process for preventing corrosion, but with the omission of the seal structure, such a plating process may be omitted. In addition, the manufacturing cost can be greatly reduced.

  Further, when the aircraft is landing or the like, a large load in the cylinder axis direction can act on the support tube 4 along with the expansion and contraction of the buffer support column 2. Since it is firmly fixed, it can resist the heavy load. Further, the rotation of the nut 51 by the insert 53 can stabilize the fixing of the support tube 4 over a long period of time.

  The landing gear is not limited to the above-mentioned configuration, and for example, as shown in FIG. 7, the orifice 33 is fixed to the inner cylinder 22 while the metering pin 34 is fixed to the outer cylinder 21. May be. In this case, the fixing mechanism 5 may be used for fixing the metering pin 34. Since the specific configuration of the fixing mechanism 5 is the same as described above, the same configuration is denoted by the same reference numeral, and the description thereof is omitted.

As described above, in this technique, when the support tube or the metering pin is fixed to the outer cylinder, the seal structure can be omitted by firmly fixing the support tube or the metering pin inside the outer cylinder. Useful as.

1 landing gear 2 buffer strut 21 outer cylinder 211 closed end 22 inner cylinder 24 internal space 31 hydraulic oil 32 nitrogen gas 33 orifice 331 orifice hole 34 metering pin 4 support tube 41 mounting part 42 fixing part 5 fixing mechanism 51 nut 52 retaining Ring 53 Insert X Tube shaft

Claims (3)

Hydraulic oil and gas are sealed in an internal space sealed by an outer cylinder whose one end is a closed end and the other end is an open end and an inner cylinder inserted from the open end into the outer cylinder. And buffer struts that can be expanded and contracted in the cylinder axis direction by relative movement of the outer cylinder and the inner cylinder,
An orifice arranged on the cylinder axis at an intermediate position in the cylinder axis direction in the internal space of the buffer strut;
The distal end portion is an attachment portion to which the orifice is attached, and the proximal end portion is a fixing portion that is fixed to the closed end in the outer cylinder, and extends in the cylinder axis direction in the inner space. A support tube disposed;
The base end side is fixed with respect to the inner cylinder and extends on the cylinder axis toward the orifice, and is inserted into the orifice with a gap therebetween, A metering pin that moves relative to the orifice as the buffer struts expand and contract,
A fixing mechanism for fixing the fixing portion of the support tube to the closed end in the outer cylinder,
The fixing mechanism is formed on the inner peripheral surface of the outer cylinder in the vicinity of the closed end and the nut that is screwed to the thread formed on the outer peripheral surface of the fixing portion of the support tube. A retaining ring fitted into the recessed groove formed,
The fixing mechanism is configured such that a nut disposed between the fixing portion and the inner peripheral surface of the outer cylinder engages with the retaining ring and the position of the nut is fixed with respect to the nut. An landing gear configured to press and fix the fixing portion of the support tube against the closing end of the outer cylinder by a reaction force accompanying the application of torque in a direction away from the closing end. The landing gear according to claim 1,
The fixing mechanism further includes an anti-rotation insert attached to protrude on an outer peripheral surface of the fixing portion on which the thread is formed,
The insert is deformed so as to crush the thread when the nut is screwed onto the outer peripheral surface of the fixing portion and the support tube is pressed against the closed end of the outer cylinder and fixed. A landing gear that acts as a stop. Hydraulic oil and gas are sealed in an internal space sealed by an outer cylinder whose one end is a closed end and the other end is an open end and an inner cylinder inserted from the open end into the outer cylinder. And buffer struts that can be expanded and contracted in the cylinder axis direction by relative movement of the outer cylinder and the inner cylinder,
By being fixed to the inner cylinder, at an intermediate position in the cylinder axis direction in the internal space of the buffer strut, an orifice disposed on the cylinder axis;
The base end portion serves as a fixed portion that is fixed to the closed end in the outer cylinder, and is disposed so as to extend on the cylinder shaft toward the orifice, leaving a gap with respect to the hole of the orifice. A metering pin that moves relative to the orifice in accordance with the expansion and contraction of the buffer strut,
A fixing mechanism for fixing the fixing portion of the metering pin to the closed end in the outer cylinder,
The fixing mechanism is formed on the inner peripheral surface of the outer cylinder in the vicinity of the closed end and the nut that is screwed to the thread formed on the outer peripheral surface of the fixing portion of the support tube. A retaining ring fitted into the recessed groove formed,
The fixing mechanism is configured such that a nut disposed between the fixing portion and the inner peripheral surface of the outer cylinder engages with the retaining ring and the position of the nut is fixed with respect to the nut. An landing gear configured to press and fix the fixing portion of the metering pin against the closed end of the outer cylinder by a reaction force accompanying the application of torque in a direction away from the closed end.

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