aircraft landing gear

Abstract

To simplify a structure of an aircraft landing gear including a steering mechanism.SOLUTION: A landing gear 1 includes a shock strut 2 having a cylinder 3 and a piston 4, and a wheel 5 supported by the piston. The shock strut has a steering mechanism 21 for rotating the wheel around a strut shaft Z together with the piston, and a power source of the steering mechanism is an electric motor 6 having a rotor 61 and a stator 62, and the rotor and the stator are coaxial with the strut shaft.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The technology disclosed herein relates to an aircraft landing gear. Background Art

[0002] Patent Document 1 describes an aircraft landing gear. This landing gear includes a steering mechanism. The steering mechanism includes a collar, a link device, and a push-pull actuator. The actuator is, for example, a hydraulic actuator. A rod slides within a strut. A wheel is supported by the rod. The collar is rotatably supported at the lower end of the strut. The link device restrains the collar and the rod such that the collar and the rod rotate integrally. The link device is a so-called torque link. When a pilot performs an operation during aircraft taxiing, the actuator rotates the collar. The rotation of the collar changes the orientation of the wheel via the link device and the rod.

[0003] Patent Document 2 describes a steering mechanism having a direct-acting actuator. The actuator has a first hydraulic chamber and a second hydraulic chamber. When hydraulic fluid is supplied to the first hydraulic chamber, the rod of the actuator moves in a first direction, changing the orientation of the wheel. When hydraulic fluid is supplied to the second hydraulic chamber, the rod of the actuator moves in a second direction, changing the orientation of the wheel to the opposite direction.

[0004] Patent Documents 3 and 4 each describe a steering mechanism including an electric motor. The electric motor is an alternative actuator to push-pull type or direct-acting actuators that use hydraulic fluid as a power source.

[0005] In the landing gear of Patent Document 3, the electric motor is fixed to a side portion of the strut. A shaft of the electric motor is connected to the collar via a speed reducer including a plurality of gears. When the shaft of the electric motor rotates, the collar rotates via the speed reducer, and the orientation of the wheel is changed by the torque link.

[0006] The landing gear described in Patent Document 4 is equipped with a harmonic drive (registered trademark). The harmonic drive is interposed between the electric motor and the collar. When the shaft of the electric motor, which is fixed to the side of the support column, rotates, the collar rotates via the harmonic drive, and the direction of the wheel changes due to the torque link. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 5711187 [Patent Document 2] Patent No. 5340072 [Patent Document 3] Japanese Patent Publication No. 2007-284054 [Patent Document 4] Japanese Patent Publication No. 2009-269596 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] Conventional steering mechanisms have a torque link. Due to its structure, the torque link restricts the direction of the wheels to within a predetermined angle. When towing an aircraft, the tagman must operate the vehicle carefully to ensure that the wheels do not exceed the restricted angle.

[0009] If the wheels reach a restricted angle due to an operational error, some kind of countermeasure is necessary for the landing gear to prevent damage to the aircraft and its fuselage.

[0010] Alternatively, ground staff can release the torque link restraint during aircraft towing, eliminating the restriction on wheel direction. In this case, operation of the torque link by ground staff is required.

[0011] Furthermore, steering mechanisms with electric motors require gears. These gears are susceptible to foreign objects such as pebbles becoming lodged in them. This can cause the steering mechanism to seize up.

[0012] Furthermore, in conventional steering mechanisms, the electric motor and the collar are constantly connected by multiple gears. This structure makes it impossible to change the direction of the wheels, for example, in the event of an electric motor failure. Conventional steering mechanisms require a clutch mechanism to release the connection between the electric motor and the collar in order to enable changes in the direction of the wheels.

[0013] These problems in conventional steering mechanisms stem from the complexity of the power transmission mechanism between the power source and the wheels.

[0014] The technology disclosed herein simplifies the structure of the landing gear of an aircraft equipped with a steering mechanism. [Means for solving the problem]

[0015] The technology disclosed herein relates to aircraft landing gear. This landing gear is A shock strut having a cylinder and a piston inserted inside the cylinder, wherein the piston is operable in the direction of the strut axis and rotatable about the strut axis relative to the cylinder supported by the machine body, The system comprises a wheel supported by the piston, The shock strut has a steering mechanism that rotates the wheel together with the piston around the strut axis, The power source for the steering mechanism is an electric motor having a rotor and a stator. The rotor and the stator are coaxial with the strut shaft.

[0016] According to this configuration, the electric motor serving as the power source is coaxial with the strut shaft. The piston rotates about the strut shaft. Since the electric motor and the piston are coaxial, the power transmission mechanism between the electric motor and the wheels is simplified. As a result, various problems occurring in conventional steering mechanisms can be solved.

[0017] The piston may constitute the rotor, and the cylinder may constitute the stator.

[0018] According to this configuration, the shock absorber strut itself having a cylinder and a piston constitutes the electric motor. When the electric motor is energized, the piston, which is the rotor, rotates relatively about the strut shaft with respect to the cylinder, which is the stator. Rotation of the piston changes the orientation of the wheels supported by the piston. This novel steering mechanism can omit torque links and gear mechanisms.

[0019] For example, if energization of the electric motor is stopped during towing of an aircraft, the piston can freely rotate relatively with respect to the cylinder. Various problems caused by restrictions on the orientation of the wheels can be solved. Furthermore, since there are no gears, foreign matter cannot get caught in gears. In addition, a clutch mechanism is also unnecessary.

[0020] In addition, the absence of torque links and gear mechanisms reduces the mass of the landing gear. Mass reduction is advantageous for energy saving of aircraft.

[0021] A permanent magnet is arranged on the piston, a coil is arranged on the inner circumferential surface of the cylinder, and the permanent magnet and the coil may face each other at least in a state where the wheels are in contact with the ground and the piston has entered the cylinder.

[0022] The piston acts relative to the cylinder in the direction of the strut axis. The relative position between the permanent magnet and the coil changes in accordance with the actuation stroke of the piston. In the landing gear having the above configuration, the permanent magnet and the coil face each other at least in a state where the wheels touch the ground and the piston enters the cylinder. When the coil is energized in this state, the piston including the permanent magnet serves as a rotor and rotates around the strut axis. The orientation of the wheels supported by the piston changes. The landing gear can change the orientation of the wheels during taxiing of an aircraft.

[0023] The shock strut is supported by the cylinder so as to be rotatable about the strut axis, and has a shaft protruding from an end of the cylinder in a direction opposite to the piston, the piston is engaged with the shaft inside the cylinder so as to be relatively movable in the direction of the strut axis with respect to the shaft and integrally rotatable in the rotational direction about the strut axis, the electric motor is located at the end of the cylinder, and the rotor may be connected to a protruding portion of the shaft.

[0024] In the landing gear of this configuration, the electric motor is located outside the cylinder. The rotor of the electric motor is connected to the shaft protruding from the end of the cylinder. When the rotor rotates, the shaft rotates around the strut axis.

[0025] The piston is engaged with the shaft inside the cylinder. The piston is capable of relative movement in the direction of the strut axis with respect to the shaft. Further, the piston can act in the direction of the strut axis relative to the cylinder. The shock strut can exert a shock absorbing function.

[0026] The piston is also engaged with the shaft so as to be integrally rotatable in the rotational direction about the strut axis with respect to the shaft. As described above, when the shaft rotates, the piston also rotates. When the piston rotates, the orientation of the wheels supported by the piston changes.

[0027] The electric motor, shaft, and piston are coaxial with the strut axis and connected to each other. The landing gear does not have a torque link or gear mechanism. In this configuration, the power transmission mechanism between the electric motor and the wheels is also simplified.

[0028] Furthermore, by cutting off the power supply to the electric motor, the motor's rotor can rotate freely. The shaft and piston, which are coaxial with and directly connected to the rotor, can rotate freely relative to the cylinder. Since the direction of the wheels is not restricted, various problems caused by restrictions on the direction of the wheels can be eliminated. Also, since there are no gears, there is no risk of foreign objects getting caught in the gears. Moreover, a clutch mechanism is unnecessary.

[0029] Furthermore, the absence of torque links and gear mechanisms reduces the mass of the landing gear.

[0030] The shaft may be a support tube that supports the orifice within the cylinder.

[0031] By using support tubes to serve both power transmission and orifice support, the structure of the landing gear is simplified. This also has the advantage of reducing the mass of the landing gear.

[0032] The electric motor may be a stepping motor.

[0033] In the steering mechanism with the above configuration, the rotation angle of the electric motor rotor and the direction of the wheels coincide. A stepping motor is suitable as a power source for the steering mechanism with the above configuration because the number of output pulses of the controller is proportional to the rotation angle of the rotor. Furthermore, since the steering mechanism with the above configuration does not require brakes, a stepping motor is also suitable as a power source in this respect.

[0034] Furthermore, stepping motors can achieve relatively high static torque. High static torque is advantageous for maintaining the orientation of the wheels in a constant direction. In this respect as well, stepping motors are suitable as a power source in the steering mechanism of the above configuration.

[0035] Another landing gear disclosed herein is: A shock strut having a cylinder and a piston inserted inside the cylinder, wherein the piston is operable in the direction of the strut axis and rotatable about the strut axis relative to the cylinder supported by the machine body, The system comprises a wheel supported by the piston, The shock strut has a steering mechanism that rotates the wheel together with the piston around the strut axis, The drive source for the steering mechanism is an electric motor having a rotor and a stator. The piston constitutes the rotor, and the cylinder constitutes the stator.

[0036] Another landing gear disclosed herein is: A shock strut having a cylinder and a piston inserted inside the cylinder, wherein the piston is operable in the direction of the strut axis and rotatable about the strut axis relative to the cylinder supported by the machine body, The system comprises a wheel supported by the piston, The shock strut is supported by the cylinder so as to be rotatable about the strut axis, and has a shaft protruding from the end of the cylinder in the direction opposite to the piston. The piston is engaged with the shaft within the cylinder such that it is movable relative to the shaft in the direction of the strut axis and can rotate integrally with the shaft in the rotational direction about the strut axis. The shock strut has a steering mechanism that rotates the wheel together with the piston around the strut axis, The drive source for the steering mechanism is an electric motor located at the end of the cylinder and having a rotor and a stator. The rotor is connected to the protruding portion of the shaft. [Effects of the Invention]

[0037] The aforementioned aircraft landing gear simplifies the power transmission mechanism between the electric motor and the wheels, thus eliminating various problems associated with conventional steering mechanisms. [Brief explanation of the drawing]

[0038] [Figure 1] Figure 1 shows the landing gear of an aircraft. [Figure 2] Figure 2 shows the II-II section of Figure 1. [Figure 3] Figure 3 shows a modified landing gear. [Modes for carrying out the invention]

[0039] The following describes an embodiment of an aircraft landing gear with reference to the drawings. The landing gear described here is illustrative.

[0040] Figure 1 shows the landing gear 1. The landing gear 1 comprises a shock strut 2 and wheels 5, 5. The landing gear 1 is the nose gear of the aircraft. The shock strut 2 has a steering mechanism 21. The steering mechanism 21 changes the direction of the wheels 5, 5.

[0041] The shock strut 2 switches between a state where it is stored in the hangar of the aircraft body 11 and a state where it is deployed from the hangar. Figure 1 shows the shock strut 2 in the deployed state and with the wheels 5, 5 in contact with the ground. In the deployed state, the strut axis Z of the shock strut 2 extends in the vertical direction. In this state, the weight of the aircraft body 11 acts on the shock strut 2.

[0042] The shock strut 2 has a cylinder 3 and a piston 4. The shock strut 2 is a so-called oleo shock strut. The cylinder 3 is substantially cylindrical. The axis of the cylinder 3 coincides with the strut axis Z. The first end (i.e., the upper end) of the cylinder 3 is closed. The upper end of the cylinder 3 is supported by the aircraft fuselage 11. The second end (i.e., the lower end) of the cylinder 3 is open.

[0043] The piston 4 is inserted into the cylinder 3 from its lower end. The piston 4 is coaxial with the cylinder 3. The piston 4 is operable relative to the cylinder 3 in the direction of the strut axis Z. The piston 4 is also rotatable relative to the cylinder 3 about the strut axis Z (see arrow in Figure 1).

[0044] The internal space 31 of the cylinder 3, formed by the cylinder 3 and the piston 4, changes in volume as the piston 4 operates. As shown in Figure 1, when the weight of the machine 11 is acting on the shock strut 2, the piston 4 is in a state where it has entered the cylinder 3. The internal space 31 is sealed with hydraulic fluid and gas (for example, nitrogen gas).

[0045] The wheels 5, 5 are located on either side of the shock strut 2. The two wheels 5, 5 are supported by the lower end of the piston 4 via the axle 51.

[0046] As mentioned above, the shock strut 2 has a steering mechanism 21. The steering mechanism 21 has an electric motor 6, which is a power source. In this landing gear 1, the electric motor 6 is made up of the shock strut 2 itself.

[0047] More specifically, the rotor 61 of the electric motor 6 is composed of pistons 4. The stator 62 of the electric motor 6 is composed of cylinders 3. The rotor 61 and stator 62 of the electric motor 6 are coaxial with the strut shaft Z.

[0048] The rotor 61 and stator 62 are positioned opposite each other in a direction perpendicular to the strut axis Z, at least when the wheel 5 is in contact with the ground and the piston 4 is entering the cylinder 3. In other words, as the piston 4 operates, the positions of the rotor 61 and stator 62 may shift in the direction of the strut axis Z.

[0049] The rotor 61 is located in the middle of the piston 4 with respect to the direction of the strut axis Z. The stator 62 is also located in the middle of the cylinder 3 with respect to the direction of the strut axis Z. More specifically, in the configuration example of Figure 1, the stator 62 is located near the lower end of the cylinder 3. Note that the position of the stator 62 is not limited to the example shown. The stator 62 can be located at any position on the cylinder 3 as long as it faces the rotor 61 of the piston 4 with respect to the direction of the strut axis Z. The position of the rotor 61 is also not limited to the example shown. The rotor 61 can be located at any position on the piston 4 as long as it faces the stator 62 of the cylinder 3 with respect to the direction of the strut axis Z.

[0050] Here, comparing the lengths of the stator 61 and stator 62 in the direction of the strut axis Z, the length of the stator 62 is longer than the length of the rotor 61. This configuration has the advantage that the rotor 61 and stator 62 can face each other even if the amount of piston 4 operating changes due to changes in the weight of the machine body 11. It should also be noted that the length of the rotor 61 may be longer than the length of the stator 62.

[0051] Figure 2 illustrates a cross-sectional view of the electric motor 6. The electric motor 6 is, for example, a stepping motor. As an example, Figure 2 shows a 5-phase, 10-coil hybrid stepping motor. The number of phases and coils of the electric motor 6 can be set as appropriate. The number of phases and coils is not limited to a specific number of phases and coils. Furthermore, the type of stepping motor is not limited to a hybrid type. The electric motor 6 may be a PM (Permanent Magnet) type stepping motor or a VR (Variable Reactance) type stepping motor. Also, the electric motor 6 is not limited to a stepping motor. The electric motor 6 may be, for example, a servo motor. Various types of motors can be used for the electric motor 6.

[0052] A permanent magnet 63 is positioned in the center of the piston 4. An iron core 64 (a gear-shaped iron core, though not shown in detail in Figure 2) is provided to surround the permanent magnet 63. The rotor 61 is formed by this permanent magnet 63 and iron core 64.

[0053] Coils 65 are arranged circumferentially on the inner surface of cylinder 3. Although not shown in detail in Figure 2, the tips of the iron cores of the coils 65 are provided with teeth corresponding to a gear-shaped core. These coils 65 constitute the stator 62.

[0054] With at least the wheels 5, 5 in contact with the ground and the rotor 61 and stator 62 facing each other, the controller 71, described later, outputs pulse waves to the stepping motor. As a result, the rotor 61 and piston 4 rotate around the strut axis Z by an angle corresponding to the number of pulse waves, either in the positive direction (for example, clockwise in Figure 2) or the negative direction (for example, counterclockwise in Figure 2). As the piston 4 rotates, the angle of the axle 51, which was perpendicular to the aircraft axis X, changes (see the solid arrow in Figure 2). The change in the angle of the axle 51 changes the orientation of the wheels 5, 5 supported by the axle 51. In this way, the steering mechanism 21 can change the orientation of the wheels 5, 5 when the aircraft is taxiing.

[0055] As shown in Figure 1, the landing gear 1 is equipped with a sensor 72. The sensor 72 is electrically connected to the controller 71. The sensor 72 outputs a position signal corresponding to the rotation angle of the piston 4 to the controller 71. The controller 71 determines the orientation of the wheels 5, 5 based on the signal from the sensor 72. During aircraft towing, the piston 4 and wheels 5, 5 rotate uncontrolled by the controller 71 by stopping the power supply to the electric motor 6. Because the controller 71 determines the orientation of the wheels 5 based on the signal from the sensor 72, the controller 71 can control the orientation of the wheels 5 through the steering mechanism 21 during taxiing.

[0056] The controller 71 is electrically connected to the control device 73. The control device 73 is installed in the cockpit. In response to the pilot's input, the control device 73 outputs an operation signal to the controller 71. The controller 71 outputs a control signal (in this case, a pulse wave) corresponding to the operation signal to the electric motor 6. Upon receiving the control signal, the rotor 61 of the electric motor 6 rotates around the strut axis Z, thereby changing the direction of the wheels 5, 5 as described above.

[0057] In this landing gear 1, the electric motor 6, which is the power source for the steering mechanism 21, is composed of the piston 4 and cylinder 3 of the shock strut 2. Compared to the steering mechanism of conventional landing gears, the structure of landing gear 1 is significantly simplified.

[0058] Specifically, the steering mechanism 21 does not have a torque link, which is necessary in conventional steering mechanisms. The torque link mechanically restricts the direction of the wheels 5, 5. In contrast, in the steering mechanism 21, which does not have a torque link, if the power supply to the electric motor 6 is stopped, the piston 4 can rotate freely relative to the cylinder 3 without restriction. Therefore, the landing gear 1 is freed from various risks that may occur during aircraft towing. Furthermore, the power supply to the electric motor 6 can be stopped, for example, by the pilot operating the control device 73 in the cockpit. This eliminates the need for ground staff to release the torque link's constraint.

[0059] Furthermore, the steering mechanism 21 does not include a gear mechanism that constitutes a reduction gear. This prevents problems such as foreign objects like pebbles getting caught in the gears.

[0060] By eliminating these torque links and gear mechanisms, the landing gear 1 can reduce its mass compared to conventional landing gears.

[0061] Furthermore, in this configuration of the steering mechanism 21, the power source is directly connected to the piston 4. This configuration of the steering mechanism 21 does not require a clutch mechanism.

[0062] In the steering mechanism 21 of this configuration, the rotation angle of the rotor 61 of the electric motor 6 matches the direction of the wheels 5, 5. The stepping motor has the characteristic that the number of output pulses of the controller 71 is proportional to the rotation angle of the rotor 61. Because the electric motor 6 is a stepping motor, the steering mechanism 21 can accurately change the direction of the wheels 5, 5.

[0063] Furthermore, the steering mechanism 21 has a structure that eliminates the need for a brake on the electric motor 6.

[0064] Furthermore, stepping motors can achieve relatively high static torque. High static torque is advantageous for maintaining the orientation of the wheels 5, 5 in a constant direction.

[0065] For these reasons, a stepping motor is suitable as a power source for the steering mechanism 21. The step angle of the stepping motor (i.e., the angle by which the rotor rotates in one pulse wave) can be set as appropriate. If the step angle is small, the steering mechanism 21 can smoothly change the direction of the wheels 5, 5.

[0066] (modified version) Figure 3 shows a modified example of the landing gear. The landing gear 10 in Figure 3 differs from the landing gear 1 in Figure 1 in that the position of the electric motor 60 is different.

[0067] The shock strut 20 includes a cylinder 30, a piston 40, a steering mechanism 210, and a support tube 8. The support tube 8 supports an orifice 81 in its internal space 31. As the piston 40 operates, the shock strut 20 absorbs the shock through the compression resistance of the gas and the resistance of the hydraulic fluid as it passes through the orifice 81.

[0068] In this configuration example, the support tube 8 is cylindrical. However, the shape of the support tube 8 is not limited to cylindrical. The support tube 8 is positioned inside the cylinder 30 so as to be coaxial with the strut axis Z. The end of the support tube 8 that is not on the piston side protrudes outward through the first end (i.e., the upper end) of the cylinder 30. The cylinder 30 supports the support tube 8 so that it can rotate around the strut axis Z. The support tube 8 does not move relative to the cylinder 30 in the direction of the strut axis Z. The end of the support tube 8 that is on the piston 40 side is located in an intermediate position within the cylinder 30.

[0069] A central hole 41 is formed in the piston 40. The central hole 41 opens at the upper end of the piston 40. The support tube 8 is inserted into the central hole 41. The piston 40 and the support tube 8 are engaged with each other so that they can move relative to each other in the direction of the strut axis Z and rotate together in the rotational direction about the strut axis Z. For example, a spline engagement portion 82 may be provided between the inner circumferential surface of the piston 40 and the outer circumferential surface of the support tube 8. Note that the engagement structure between the piston 40 and the support tube 8 is not limited to spline engagement. Various known engagement structures can be used.

[0070] The power source for the steering mechanism 210 is an electric motor 60. The electric motor 60 is located at the end of the cylinder 30 opposite the piston 40. The electric motor 60 is supported by the cylinder 30.

[0071] The electric motor 60 has a rotor 61 and a stator 62. The electric motor 60 may be a stepping motor, similar to the landing gear 1 described above. In this configuration of the landing gear 10, the use of a stepping motor brings the various advantages mentioned above to the landing gear 10. Various types of motors can be used for the electric motor 60.

[0072] The rotor 61 of the electric motor 60 is connected to a protruding portion of the support tube 8. The electric motor 60 is directly connected to the support tube 8. When the rotor 61 rotates, the support tube 8 and the piston 40 rotate relative to the cylinder 30 around the strut axis Z. In addition to supporting the orifice 81, the support tube 8 also has the function of transmitting power from the electric motor 60 to the piston 40. The support tube 8 constitutes part of the steering mechanism 210.

[0073] During taxiing, the control device 73 outputs an operation signal to the controller 71 in response to the pilot's input. The controller 71 outputs a control signal corresponding to the operation signal to the electric motor 60. Upon receiving the control signal, the rotor 61 of the electric motor 60 rotates around the strut axis Z. As the rotor 61 rotates, the angle of the axle 51 changes via the support tube 8 and piston 40. This changes the orientation of the wheels 5, 5. The sensor 72 outputs a position signal corresponding to the rotation angle of the piston 4 to the controller 71.

[0074] During towing, the power supply to the electric motor 60 is cut off according to the pilot's input. The piston 40 can rotate freely relative to the cylinder 30 without restriction. The landing gear 10 is freed from various risks that may occur during aircraft towing.

[0075] In this landing gear 10, the rotor 61 and stator 62 of the electric motor 60 are coaxial with the strut axis Z of the shock strut 20. The electric motor 60 is substantially directly connected to the piston 40. The structure of the landing gear 10 is simple.

[0076] Like landing gear 1, landing gear 10 also lacks a torque link and a gear mechanism that constitutes a reduction gear. By omitting these power transmission mechanisms, landing gear 10 is freed from the various disadvantages mentioned above.

[0077] Furthermore, because the electric motor 60 is located outside the shock strut 20, the maintainability of the electric motor 60 is improved.

[0078] In the landing gear 10, the support tube 8 serves both to support the orifice 81 and to transmit power. In contrast, the shock strut 20 may have a shaft that transmits power only. The first end of the shaft is connected to the rotor 61 of the electric motor 60 outside the cylinder 30. The second end of the shaft engages with the piston 40 inside the cylinder 30. The piston 40 is engaged with the shaft so that it is movable relative to the shaft in the direction of the strut axis Z and can rotate integrally in the rotational direction about the strut axis Z. This allows the shaft to transmit power from the electric motor 60 to the piston 40. The electric motor 60 is substantially directly connected to the piston 40. When the rotor 61 of the electric motor 60 rotates, the piston 40 rotates about the strut axis Z, changing the orientation of the wheels 5, 5. [Explanation of Symbols]

[0079] 1. Landing gear 10 Landing gear 11 aircraft 2 Shock strut 20 Shock Strut 21 Steering mechanism 3 cylinders 30 cylinders 4 pistons 40 pistons 5 wheels 6 Electric motor 60 Electric motors 61 Rotor 62 Stator 63 Permanent Magnets 65 coils 8. Support tube (shaft) 81 Orifice Z strut shaft

Claims

1. A shock strut having a cylinder and a piston inserted inside the cylinder, wherein the piston is operable in the direction of the strut axis and rotatable about the strut axis relative to the cylinder supported by the machine body, The system comprises a wheel supported by the piston, The shock strut has a steering mechanism that rotates the wheel together with the piston around the strut axis, The power source for the steering mechanism is an electric motor having a rotor and a stator. The rotor and the stator are coaxial with the strut shaft. The shock strut is supported by the cylinder so as to be rotatable about the strut axis, and has a shaft protruding from the end of the cylinder in the direction opposite to the piston. The piston is engaged with the shaft within the cylinder such that it is movable relative to the shaft in the direction of the strut axis and can rotate integrally with the shaft in the rotational direction about the strut axis. The electric motor is located at the end of the cylinder, The rotor is connected to a protruding portion of the shaft, and the rotor is part of the landing gear of an aircraft.

2. In the aircraft landing gear according to claim 1, The shaft is a support tube that supports an orifice within the cylinder, in the landing gear of an aircraft.

3. In the aircraft landing gear according to claim 1 or 2, The aforementioned electric motor is a stepping motor, used in the landing gear of an aircraft.

4. In the aircraft landing gear according to Claim 1, An aircraft landing gear wherein the end of the shaft penetrates the end of the cylinder and protrudes from inside the cylinder in the opposite direction to the piston.

5. The aircraft landing gear according to Claim 4, The stator is located outside the cylinder and faces the rotor, and is part of the landing gear of an aircraft.

6. A shock strut having a cylinder and a piston inserted inside the cylinder, wherein the piston is operable in the direction of the strut axis and rotatable about the strut axis relative to the cylinder supported by the machine body, The system comprises a wheel supported by the piston, The shock strut is supported by the cylinder so as to be rotatable about the strut axis, and has a shaft protruding from the end of the cylinder in the direction opposite to the piston. The piston is engaged with the shaft within the cylinder such that it is movable relative to the shaft in the direction of the strut axis and can rotate integrally with the shaft in the rotational direction about the strut axis. The shock strut has a steering mechanism that rotates the wheel together with the piston around the strut axis, The power source for the steering mechanism is an electric motor located at the end of the cylinder and having a rotor and a stator. The rotor is connected to a protruding portion of the shaft, and the rotor is part of the landing gear of an aircraft.

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