Brake mechanism

Abstract

To provide a brake mechanism capable of smoothly and stably tilting an operation lever portion operating a brake, for a long period.SOLUTION: A brake mechanism is composed of an operation lever portion 3, a first link member 21, a second link member 22, and a third link member, and is equipped with a link mechanism 4 whose mode is changed between a non-braking mode in which a brake is not applied in normal conditions, a braking normal mode in which a brake is applied, and a braking holding mode in which it is held while braking. In the non-braking mode, the operation lever 3 is held at a non-operating position and the first link member 21 is held at a non-braking position. In the braking normal mode, the operation lever portion 3 is tilted to a braking position, thereby converting the first link member 21 to the braking position. In the braking holding mode, the operation lever portion 3 is tilted to a lock portion, thereby changing the position of the first link member 21 to the braking position to be held.SELECTED DRAWING: Figure 2

Description

Technical Field

[0002] , , , , , , ,

[0003]

[0001] The present invention relates to a brake mechanism disposed in a wheelchair, a walker, a walking assist device, and the like.

Background Art

[0002] Generally, in a wheelchair, a walker, a walking assist device, etc., a handle part operated by a user or an assistant is provided, and a brake device having a brake lever is disposed on the handle part. In such a wheelchair or walker, etc., a user or an assistant holding the handle part can apply a brake to the wheels by operating the brake lever.

[0003] For example, Patent Document 1 proposes a brake device having a brake lever. This brake device is configured such that the brake lever can be displaced to a standby position, a brake position where it is tilted upward (toward the handle part) from the standby position, and a lock position where it is tilted downward (opposite to the handle part) from the standby position. When the brake lever is in the standby position, no brake is applied to the wheels. When the brake lever is tilted to the brake position, a brake is applied to the wheels. Further, when the brake lever is tilted to the lock position, rotation of the wheels is prohibited. Such a configuration is such that a rotation shaft provided on the brake lever is rotatably supported by a shaft hole part of a cover member, and a protruding part provided on the brake lever is movably provided along a guide passage formed in the cover member. The brake lever can be displaced to the above-described standby position, brake position, and lock position by tilting about the rotation shaft while the protruding part moves along the guide passage. Here, the guide passage is composed of an upper passage part having a substantially U-shape and a lower passage part bent forward from the lower end of the upper passage part. The brake lever is displaced to the standby position and the brake position by moving the protruding part up and down along the upper passage part, while it is displaced to the lock position by moving the protruding part to the lower passage part. <00000​​​​

[0004] [Patent Document 1] Japanese Patent Publication No. 2019-180615 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] In the conventional brake system described above, the guide passage for the brake lever is bent into an upper passage section and a lower passage section. This bend hinders the movement of the protruding part, making it difficult to tilt the brake lever smoothly. Furthermore, when the brake lever moves back and forth between the upper and lower passage sections, the protruding part of the brake lever strikes the bend between the upper and lower passage sections, causing wear on both. This wear could reduce the stability of the movement that displaces the brake lever to the locked position. Thus, there was room for improvement in the conventional brake system.

[0006] This invention proposes a brake mechanism that allows the brake lever to tilt smoothly and to remain stably displaced to a predetermined position over a long period of time. [Means for solving the problem]

[0007] The present invention relates to a brake mechanism comprising a brake unit that applies brakes to the wheels that move the vehicle body, and a brake operating unit attached to a handle unit that controls the movement of the vehicle body, and operating the brake unit via a wire connected to the brake unit, wherein the brake operating unit comprises an operating base unit fixed to the handle unit and an operating lever unit tiltably provided on the operating base unit, and the operating lever unit is held in a non-operating position where the brake unit does not apply the brakes, and is tilted from the non-operating position toward the handle unit to change its position to an operating position where the brake unit applies the brakes, wherein the brake operating unit comprises a link mechanism unit composed of the operating lever unit, a first link member, a second link member, and a third link member, the first link member having one end tiltably attached to a tilting shaft provided on the operating base unit and the other end to which the wire is attached, and the position is changed by tilting via the wire between a braking position where the brake unit applies the brakes and a non-braking position where the brakes do not apply The link mechanism is configured such that the second link member is tiltably mounted on the tilting shaft, the third link member is tiltably connected to the second link member and has a braking holding portion that contacts the first link member in the braking position, the operating lever portion comprises a first pivot portion tiltably connected to the first link member and a second pivot portion provided at a different location from the first pivot portion and tiltably connected to the third link member, and the link mechanism is configured such that the operating lever portion is normally positioned in the non-operating position Furthermore, the first link member is kept in a non-braking state with the non-braking position, and the operating lever portion is tilted from the non-braking position to the operating position, thereby changing the position of the first link member from the non-braking position to the braking position, and the braking holding portion of the third link member is converted to a normal braking state in which it does not contact the first link member, while the operating lever portion is tilted from the non-braking position to the locked position opposite to the handle portion, thereby changing the position of the first link member from the non-braking position to the braking position,Furthermore, the braking mechanism is characterized in that the braking and holding portion of the third link member abuts against the first link member, thereby converting the first link member into a braking and holding mode in which it is held in the braking position.

[0008] In this configuration, the tilting of the operating lever causes the link mechanism to switch between a non-braking mode where the brake is not applied, a normal braking mode where the brake is applied, and a brake-holding mode where the brake is held in the applied state. Thus, since this configuration operates the brake by linking the operating lever and the first to third link members, the operating lever can be tilted (position changed) more smoothly than the conventional configuration described above (a configuration that guides along a guide path), and the occurrence of wear that is prone to occur in the conventional configuration can be suppressed. Therefore, the operation of changing the position of the operating lever (in other words, the link operation that changes the link mechanism to each mode) can be performed stably over a long period of time.

[0009] In this configuration, the link mechanism is configured to hold the first link member in a braking position by bringing the braking holding portion of the third link member into contact with the first link member in the braking-holding configuration. The configuration can be changed from the braking-holding configuration by releasing the contact between the braking holding portion of the third link member and the first link member. Specifically, the contact can be released relatively easily by tilting the operating lever from the locked position to the non-operating position, thereby returning to the normal non-braking configuration. In this way, the user can release the contact between the braking holding portion of the third link member and the first link member in the braking-holding configuration by using the force of tilting the operating lever.

[0010] In the brake mechanism of the present invention described above, a configuration is proposed in which the second link member of the link mechanism is provided so as not to come into contact with the operating lever.

[0011] In this configuration, the second link member, which is not directly connected to the operating lever, is provided so as not to come into contact with the operating lever. As a result, the link mechanism as a whole can operate more smoothly, and the operating lever can be tilted more smoothly. This further suppresses wear in the link mechanism. [Effects of the Invention]

[0012] The brake mechanism of the present invention allows for stable operation of the brake section through the linkage of the link mechanism, and also allows the operating lever section to be smoothly and stably tilted between the non-operating position, the operating position, and the locked position over a long period of time. [Brief explanation of the drawing]

[0013] [Figure 1] This is an external view showing the brake operating unit 2 attached to the handle unit 101. [Figure 2] This is an explanatory diagram showing the link mechanism 4 located inside the operating base 5. [Figure 3] (A) An explanatory diagram showing a portion of the link mechanism 4 cut out, and (B) A cross-sectional view of the link mechanism 4. [Figure 4] This is an explanatory diagram showing the conversion of the link mechanism 4 from a non-braking state to a normal braking state. [Figure 5] This is an explanatory diagram showing the conversion of the link mechanism 4 from a non-braking state to a braking and holding state. [Figure 6] This is an explanatory diagram showing the transformation of the link mechanism 4, continuing from Figure 5. [Modes for carrying out the invention]

[0014] An embodiment of the brake mechanism according to the present invention will be described in detail below. The brake mechanism 1 of this embodiment is mainly installed in wheelchairs, walkers, and walking aids, and as shown in Figure 1, it includes a brake operating unit 2 fixed to the handle portion 101 of the wheelchair, etc. Some wheelchairs, walkers, and walking aids are equipped with a pair of left and right handle portions 101 that are operated by the user or caregiver, and the brake operating unit 2 of this embodiment is installed on the left and right handle portions 101 respectively. In the following, only the brake operating unit 2 fixed to one of the left or right handle portions 101 will be described, but of course the same brake operating unit 2 can be installed on the other handle portion 101 as well.

[0015] The aforementioned wheelchair, walker, and walking aid have a frame that forms the body (not shown), and at least one pair of left and right wheels (not shown) are mounted on the frame. The frame is made of metal pipe or the like, and is provided with a handle frame portion 102 that constitutes the handle portion 101. As shown in Figure 1, a grip portion 103 is attached to the handle frame portion 102 to form the handle portion 101. The left and right wheels are each provided with a brake portion (not shown) that applies a brake to the wheel. One end of a wire 9 (see Figure 1) is connected to this brake portion, and when the wire 9 is pulled, the wheel is braked (in other words, a braking force is applied). The brake portion is also provided with a biasing means (for example, a coil spring) that biases the wire 9 toward the one end side (the brake portion side). As a result, the wire 9 is normally biased toward the brake portion side, so the brake by the brake portion does not apply to the wheel. Since these brakes can be constructed using drum brakes, rim brakes, or disc brakes, which are commonly used in wheelchairs and walkers, a detailed explanation will be omitted.

[0016] The essential parts of the present invention will be described below. The brake mechanism 1 is composed of the above-described brake part and the brake operation part 2. As shown in FIG. 1, the brake operation part 2 includes an operation base part 5 attached to the handle frame part 102 and an operation lever part 3 tiltably attached to the operation base part 5. The operation base part 5 is integrally provided with a fixing part 11 fixed to the handle frame part 102 and a case part 12 in which a link mechanism part 4 described later is disposed.

[0017] As shown in FIGS. 1 to 3, the case part 12 of the brake operation part 2 is composed of a pair of front and back case plate parts 13, 13 provided to face each other at a predetermined interval and a wall part 14 connecting the two case plate parts 13, 13, and an opening part 15 opened to the right on the paper surface of each figure is formed. Further, an insertion hole 16 through which the wire 9 is inserted is formed by opening at the lower part of the wall part 14 of the case part 12.

[0018] The link mechanism part 4 is provided in the case part 12. The link mechanism part 4 is composed of the above-described operation lever part 3, the first link member 21, the second link member 22, and the third link member 23, and the first to third link members 21 to 23 are housed inside the case part 12. The first link member 21 and the second link member 22 are tiltably attached to a tilt axis 17 provided on the case part 12. Here, the tilt axis 17 is passed through the front and back case plate parts 13, 13.

[0019] The operation lever part 3 is composed of a lever main part 31 operated by the user or the caregiver, and a pair of front and back lever bases 32, 32 provided in a bifurcated manner from the lever main part 31. The operation lever part 3 is arranged such that the lever bases 32, 32 are disposed inside the case part 12, and the lever main part 31 protrudes to the right side (the right side in the drawing) of the case part 12 through the opening 15 of the case part 12. The front and back lever bases 32, 32 are provided to face each other with a predetermined gap therebetween, and the first link member 21 and the third link member 23 can be inserted through this gap. Further, the front and back lever bases 32, 32 are respectively provided with a first pivot part 33 tiltably connected to the first link member 21 and a second pivot part 34 tiltably connected to the third link member 23. A first shaft part 36 is passed to the front and back first pivot parts 33, 33, and a second shaft part 37 is passed to the front and back second pivot parts 34. The first shaft part 36 and the second shaft part 37 are provided parallel to the tilt axis 17.

[0020] The first link member 21 is formed in a strip shape, one end is tiltably attached to the tilt axis 17, and the other end is attached to the other end of the wire 9. The first link member 21 tilts in the vertical direction around the tilt axis 17 inside the case part 12. An arc-shaped notch 26 is formed at the other end of the first link member 21, and a cylindrical sliding member 10 to which the other end of the wire 9 is attached is slidably supported in the notch 26. The wire 9 attached to the sliding member 10 is disposed to reach the brake part through the insertion hole 16 of the case part 12. Further, a first shaft part 36 provided at the first pivot parts 33, 33 of the operation lever part 3 is tiltably inserted through a part between one end and the other end of the first link member 21. Thereby, the first link member 21 and the operation lever part 3 are relatively tiltably connected.

[0021] The first link member 21 tilts about the tilting axis 17, thereby changing its position between the non-braking position shown in Figure 2 and the braking positions shown in Figures 4(B) and 6(B). When the first link member 21 is in the non-braking position, the other end of the wire 9 (sliding member 10) is on the brake side compared to the braking position, so the brake is not applied by the brake. On the other hand, when the first link member 21 is in the braking position, the wire 9 is pulled away from the brake side compared to the braking position, so the brake is applied by the brake. Furthermore, the other end of the first link member 21 (notch 26) is pulled via the wire 9 by the biasing means (coil spring) of the brake, and is constantly biased in a clockwise direction on the plane of Figure 2.

[0022] The second link member 22 is formed in a curved plate shape, with one end tiltably attached to the tilting shaft 17 and the third link member 23 tiltably connected to the other end. In this embodiment, as shown in Figure 3(B), two second link members 22, 22 are arranged at a predetermined distance from each other on both the front and back sides of the first link member 21 (and the third link member 23), and are respectively attached to the tilting shaft 17. These two second link members 22, 22 and the first link member 21 can each tilt about the tilting shaft 17. As shown in Figure 4, although these second link members 22 can tilt in the left-right direction (left-right direction on the plane of the paper) inside the case portion 12, there is a limit to the position in which they can tilt to the left by contacting the wall portion 14 of the case portion 12.

[0023] These second link members 22 are provided so as not to come into contact with the operating lever portion 3. In particular, the second link member 22 is provided with a curved recess 27 at the portion facing the lever base 32 of the operating lever portion 3, so that when the operating lever portion 3 is tilted downward as will be described later, the second pivot portion 34 of the operating lever portion 3 and the curved recess 27 of the second link member 22 do not come into contact.

[0024] The third link member 23 is formed in the shape of a strip plate, and one end is tiltably connected to the other end of the second link member 22. Here, one end of the third link member 23 is inserted through a third shaft portion 38 that spans across the front and back of the second link members 22, 22, thereby tiltably connecting the second link members 22, 22 and the third link member 23. The other end of the third link member 23 is coupled with a braking holding portion 41 that abuts against the first link member 21 and a tilting limiting portion 42. The third link member 23 tilts about the third shaft portion 38, and is held in the non-braking position when the tilting limiting portion 42 abuts against the first link member 21 in the non-braking position, while it can be held in the braking position when the braking holding portion 41 abuts against the first link member 21 in the braking position. The third shaft portion 38 is provided parallel to the tilting axis 17 described above.

[0025] Furthermore, the portion of the third link member 23 closest to the braking and holding portion 41 and the tilt limiting portion 42 is tiltably inserted into the second shaft portion 37 provided on the second pivot portions 34, 34 on the front and back of the operating lever portion 3. In this way, the third link member 23 and the operating lever portion 3 are connected in a way that allows them to tilt relative to each other.

[0026] The link mechanism 4 is converted between a non-braking state, a normal braking state, and a braked-holding state by the coordinated movement of the operating lever 3 and the first to third link members 21 to 23. In the non-braking state, as shown in Figures 2 and 3, the first link member 21 is in the non-braking position, the second link member 22 is in contact with the wall 14 of the case 12, and the tilt limiting portion 42 of the third link member 23 is in contact with the first link member 21. In other words, in the non-braking state, the first link member 21, which is always biased in the clockwise direction, is held in the non-braking position by the second link member 22 in contact with the wall 14 and the third link member 23, whose tilt limiting portion 42 is in contact with the first link member 21. In this non-braking state, the position of the operating lever 3 is the non-operation position, and the link mechanism 4 is normally kept in a non-braking state.

[0027] As shown in Figure 4, the normal braking mode is activated when the operating lever 3 is tilted upward (towards the grip portion 103 of the handle portion 101) from the non-operating position, thereby converting from the non-braking mode. In this embodiment, the operating lever 3 and the first to third link members 21 to 23 tilt integrally around the tilt axis 17, thereby converting from the non-braking mode to the normal braking mode. In the normal braking mode, as shown in Figure 4(B), the first link member 21 is in the braking position, and the second link member 22 is separated from the wall portion 14 of the case portion 12. Therefore, the normal braking mode is not maintained, and when the force tilting the operating lever 3 upward is released, the biasing force pulling the wire 9 toward the brake portion causes the first link member 21 to tilt clockwise, and consequently the link mechanism 4 returns from the normal braking mode to the non-braking mode. The position of the operating lever 3 in this normal braking mode is the operating position.

[0028] As shown in Figures 5 and 6, the braking and holding configuration is achieved when the operating lever portion 3 is tilted downward (to the opposite side of the grip portion 103) from the non-operating position. In this conversion to the braking and holding configuration, the second link member 22 is in contact with the wall portion 14 of the case portion 12 and cannot be tilted to the left (to the left on the plane of the paper). As a result, the first link member 21 and the third link member 23 move in conjunction with the tilting of the operating lever portion 3. More specifically, as shown in Figures 5(A) to 5(B), the first link member 21 tilts upward from the non-braking position, and the tilt limiting portion 42 of the third link member 23 moves away from the first link member 21. Furthermore, as the operating lever portion 3 tilts, as shown in Figure 6(A), the second pivot portion 34 of the operating lever portion 3 moves toward the curved recess 27 of the second link member 22, and the third link member 23 tilts to the left (to the left on the plane of the paper). Subsequently, as shown in Figure 6(B), when the first link member 21 is in the braking position, the second pivot portion 34 of the operating lever portion 3 is positioned opposite the curved recess 27 of the second link member 22, and the braking and holding portion 41 of the third link member 23 comes into contact with the first link member 21. In this way, the link mechanism 4 is transformed into a braking and holding configuration.

[0029] In this braking and holding configuration, the first link member 21, which is always biased clockwise, is held in the non-braking position by the second link member 22, which is in contact with the wall portion 14, and the third link member 23, whose braking and holding portion 41 is in contact with the first link member 21. As a result, the link mechanism 4 is held in the braking and holding configuration unless an external force (force from the user or caregiver) acts on the operating lever portion 3. In other words, it is kept in a state where the brake is applied by the brake portion. The position of the operating lever portion 3 in this braking and holding configuration is the locked position, and by setting the operating lever portion 3 to the locked position, the first link member 21 is held in the non-braking position against the biasing force pulling the wire 9 toward the brake portion (in other words, it is held in the braking and holding configuration).

[0030] The braking hold state is released when the user or caregiver tilts the operating lever 3 upward (towards the grip 103), thereby converting from the braking hold state to the non-braking state. In this conversion, the upward tilting of the operating lever 3 causes the first link member 21 and the third link member 23 to move in the opposite direction to the movement that led to the braking hold state, returning to the non-braking state (see Figures 5 and 6). In this way, the braking hold state can be released relatively easily by the user or caregiver gripping the operating lever 3.

[0031] As described above, the brake mechanism 1 of this embodiment is installed on a wheelchair or walker and is operated by the user of the wheelchair or walker or their caregiver. When moving the wheelchair or walker, the user or caregiver holding the handle 101 keeps the operating lever 3 in the non-operation position without operating it. As a result, the link mechanism 4 is kept in the non-braking state, and the wheels are not braked, allowing for easy movement. When stopping the wheelchair or reducing the speed, the user or caregiver grips the operating lever 3 and tilts it to the braking position. As a result, the link mechanism 4 changes from the non-braking state to the normal braking state (see Figure 4), and the wheels are braked. When the wheelchair stops or the desired speed is reached, the user releases the operation of the operating lever 3, and the link mechanism 4 returns to the non-braking state. On the other hand, when parking a wheelchair or the like, the user tilts the operating lever 3 from the non-operating position to the locked position. This converts the link mechanism 4 from the non-braking state to the braked-holding state (see Figures 5 and 6), and as it is held in this braked-holding state, the wheels remain braked (parked). After this, when moving the wheelchair or the like, the user grips the operating lever 3 and tilts it from the locked position to the non-operating position. This converts the link mechanism 4 from the braked-holding state to the non-braking state, and the brakes are released.

[0032] Thus, the brake mechanism 1 of this embodiment is configured to apply the brakes to the wheels by switching the link mechanism 4 between a non-braking mode, a normal braking mode, and a brake-holding mode as needed. The link mechanism 4 is switched between each of the aforementioned modes by moving the operating lever 3, which is operated by the user, in conjunction with the first to third link mechanisms 21 to 23, so that the switch between each mode can be performed easily and smoothly.

[0033] The link mechanism 4 is structured so that the operating lever 3 does not come into contact with the link members 21-23, except when the first link member 21 and the third link member 23 are actively pressed together when converting to each mode. More specifically, the first link member 21 and the third link member 23 are configured so that they do not slide relative to each other while remaining in contact when converting to each mode, thereby suppressing wear between them. Furthermore, the operating lever 3 is configured not to come into contact with the second link member 22. Here, as mentioned above, the second link member 22 becomes unable to tilt due to the wall portion 14 of the case portion 12 in the non-braking mode and the braking-holding mode. In this non-tilting state, by preventing contact between the operating lever 3, which is operated by the user, etc., and the second link member 22, wear does not occur when converting to these modes. In this way, the link mechanism 4 of this embodiment can suppress wear when converting to each mode, so that it can be converted to each mode stably and easily even when repeatedly converted over a long period of time.

[0034] Therefore, according to the brake mechanism 1 of this embodiment, the operating lever portion 3 can be tilted stably and smoothly to the non-operating position, operating position, and locked position, making it easy for the user or caregiver to operate over a long period of time.

[0035] The present invention is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. For example, the dimensions and shapes of each part in the embodiments described above can be changed as appropriate. In this embodiment, the wire is biased by a coil spring in the brake section, but the system is not limited to this configuration. For example, a biasing means (coil spring, leaf spring, air cylinder, gas cylinder, etc.) for biasing the wire can be provided in the brake operating section. Alternatively, the brake operating section can be equipped with a biasing means for biasing the operating lever to the non-operating position. In this embodiment, the operating lever (first pivot point, second pivot point) and the second link member are not in contact. However, the configuration is not limited to this, and for example, in the braking and holding mode, the second pivot point of the operating lever can be in contact with the second link member. In this embodiment, the first link member and the third link member are connected so as to be tiltable by the lever bases on the front and back of the operating lever and the second link members on the front and back (a so-called double-supported structure). However, the structure is not limited to this, and it may also be a structure in which the lever base of the operating lever and the second link member, which are located on one side of the operating lever, are connected so as to be tiltable (a so-called cantilevered structure). [Explanation of Symbols]

[0036] 1. Brake mechanism 2. Brake operation section 3. Operating lever section 4. Link mechanism 5. Operating base section 9 wires 10 Sliding member 11 Fixed part 12 Case section 13. Case Panel 14 Wall 15 Opening 16 Through hole 17 Tilt axis 21 First link member 22 Second link member 23 Third link member 26 Notch 27 Curved recess 31 Lever main part 32 Lever base 33 First pivot point 34 Second Pivotal Connection 36 First shaft part 37 Second shaft part 38 Third shaft part 41 Brake holding part 42. Tilt limiting section 101 Handle section 102 Handle frame section 103 Grip section

Claims

1. The braking unit applies brakes to the wheels that move the vehicle, A brake operating unit is attached to the handle portion that controls the movement of the vehicle body, and via a wire connected to the brake portion, the brake operating unit controls the brake portion. Equipped with, The aforementioned brake operating unit The system comprises an operating base fixed to the handle portion and an operating lever portion tiltably mounted on the operating base portion. In a brake mechanism in which the operating lever portion is held in a non-operating position where the brake portion does not apply the brake, and is tilted toward the handle portion from the non-operating position to change its position to an operating position where the brake portion applies the brake, The brake operating section comprises a link mechanism consisting of the operating lever section, a first link member, a second link member, and a third link member. The first link member is tiltably attached at one end to a tilting shaft provided on the operating base and has the wire attached to the other end, and by tilting, its position is changed between a braking position in which the brake is applied by the brake unit via the wire and a non-braking position in which the brake is not applied. The second link member is tiltably mounted on the tilting shaft, The third link member is tiltably connected to the second link member and is provided with a braking and holding portion that contacts the first link member in the braking position. The operating lever portion comprises a first pivot portion that is tiltably connected to the first link member, and a second pivot portion that is provided at a different location from the first pivot portion and tiltably connected to the third link member. The aforementioned link mechanism is Under normal conditions, the operating lever portion is kept in the non-operating position and the first link member is kept in the non-braking position, thus maintaining a non-braking dynamic state. As the operating lever portion is tilted from the non-operating position to the operating position, the first link member is repositioned from the non-braking position to the braking position, and the braking holding portion of the third link member is converted to a normal braking mode in which it does not contact the first link member. A brake mechanism characterized in that the operating lever portion is tilted from the non-braking position to the locked position opposite to the handle portion, thereby changing the position of the first link member from the non-braking position to the braking position, and the braking holding portion of the third link member comes into contact with the first link member, thereby changing the configuration to a braking holding configuration in which the first link member is held in the braking position.

2. The brake mechanism according to claim 1, characterized in that the second link member of the link mechanism is provided so as not to come into contact with the operating lever.

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