CN117916150A - Vehicle with a wheel - Google Patents

Abstract

A vehicle including a self-centering mechanism is described. The vehicle includes a frame, a fork arranged to rotate relative to the frame about an axis of rotation, a wheel connected to the fork, and a self-centering mechanism for centering a position of the wheel. The self-centering mechanism includes a cam, a follower engaged with the cam, and a biasing member biasing the follower relative to the cam. Rotation of the fork relative to the frame rotates the follower relative to the cam about the axis of rotation. In addition, the cam is shaped such that the follower is biased to a rest position by the biasing member, and rotation of the follower relative to the cam moves the follower from the rest position and translates relative to the cam in a direction parallel to the axis of rotation under the influence of the biasing member.

Description

Vehicle with a wheel

Technical Field

The present invention relates to a vehicle comprising a self-centering mechanism for a wheel of the vehicle.

Background

Vehicles such as bicycles or scooters typically include a steering assembly for steering the wheels of the vehicle. Bumps, dimples, and other uneven features on the ground may exert forces on the steering assembly as the vehicle moves over the ground. Such forces may adversely affect the stability and control of the vehicle.

Disclosure of Invention

The invention relates to a vehicle comprising: a frame; a fork arranged to rotate relative to the frame about an axis of rotation; a wheel connected to the fork; and a self-centering mechanism for centering a position of the wheel, the self-centering mechanism comprising: a cam, a follower engaged with the cam; and a biasing member for biasing the follower against the cam, wherein: rotation of the fork relative to the frame causes rotation of the follower relative to the cam about the axis of rotation; and the shape of the cam is such that the follower is biased to a rest position by the biasing member, and rotation of the follower relative to the cam moves the follower from the rest position and translates (translate) relative to the cam in a direction parallel to the axis of rotation under the influence of the biasing member.

Alternatively, the follower may comprise an elongate member engaged with the cam. Alternatively, the elongate member may comprise a longitudinal axis which is perpendicular to the axis of rotation. Alternatively, a first end of the elongate member may be engaged with a first portion of the cam and a second end of the elongate member may be engaged with a second portion of the cam. Optionally, at least a portion of the elongate member may be rotatable about an axis perpendicular to the axis of rotation. Alternatively, the elongate member may comprise a rod or pin. Alternatively, the follower may comprise a circular cross-section.

Alternatively, the follower may comprise a rotatable portion engaged with the cam, and the rotatable portion may be arranged to rotate about an axis perpendicular to the axis of rotation. Alternatively, the follower may comprise a first rotatable portion engaged with a first portion of the cam and a second rotatable portion engaged with a second portion of the cam, and each of the first and second rotatable portions may be arranged to rotate about a respective axis perpendicular to the axis of rotation. Optionally, the first rotatable portion and the second rotatable portion rotate about a common axis. Optionally, the rotatable portion or each of the first rotatable portion and the second rotatable portion may comprise a bearing.

Optionally, the cam may include a limiter to limit rotation of the follower relative to the cam to a predetermined angle of rotation. Alternatively, the cam may comprise a track along which the follower moves. Optionally, the stop may be provided at one end of the track and/or limit movement of the follower along the track. Alternatively, the stopper may extend in a direction parallel to the rotation axis. Alternatively, the predetermined angle of rotation may be between 30 and 60 degrees from the rest position.

Optionally, the follower may be arranged to translate relative to the cam within a slot for guiding translation of the follower relative to the cam. Optionally, the fork may comprise the slot. Alternatively, the fork may comprise two slots through which the follower extends. Alternatively, the two slots may be diametrically opposed about the axis of rotation. Alternatively, the or each slot may extend parallel to the axis of rotation. Optionally, the or each slot may inhibit rotation of the follower relative to the fork about the axis of rotation.

Optionally, the cam may include one or more tracks, the follower may engage and move along the tracks when the follower rotates relative to the cam, and the biasing member may bias the follower relative to the tracks.

Optionally, the cam may include a track having an inflection point, the follower may engage and move along the track when the follower rotates relative to the cam, the biasing member may bias the follower relative to the track toward the inflection point, and the follower may be in the rest position when the follower is located at the inflection point. Alternatively, the track may comprise a profile having a slope that is linear or increases in a direction away from the inflection point. Optionally, the resistance of the biasing member increases as the follower translates along the axis of rotation away from the inflection point. Alternatively, the track may have a V-shaped or U-shaped profile.

Optionally, the cam may comprise a first track and a second track, each track engaging a respective portion of the follower. Optionally, the first track may be radially opposite (oppose) the second track with respect to the rotation axis. Alternatively, the first track and the second track may be different such that in response to rotation of the follower relative to the cam, a respective portion of the follower engages only one of the first track or the second track. Optionally, the or each track comprises a V-shaped profile.

Alternatively, the cam may be annular. Alternatively, the cam may comprise an annular body having one or more tracks formed in or on the annular body.

Alternatively, the biasing member may be located within a tube of the fork. Alternatively, the biasing member may comprise a spring. Alternatively, the biasing member may comprise a coil spring. Alternatively, the biasing member may be configured to expand and retract within the fork in a direction parallel to the rotational axis. Optionally, the biasing member is engaged with the follower.

Optionally, the biasing force increases as the follower moves from the rest position.

Alternatively, the cam may surround the tube of the fork. Alternatively, the fork may extend through the cam. Optionally, the fork comprises a tube in which the biasing member is located.

Alternatively, the follower may comprise a body movable within a tube of the fork. Alternatively, the body may be restrained by the tube of the fork to prevent tilting of the body within the tube. Alternatively, the follower may comprise an elongate member extending through the body. Alternatively, the body may be disc-shaped. Alternatively, the biasing member may urge the body. Optionally, the body may include a surface against which the biasing member abuts.

Alternatively, the cam may be connected to the inside of the tube of the frame. Alternatively, the cam may be connected to the inside of the head pipe of the frame.

Alternatively, the wheel may be a front wheel of the vehicle.

Optionally, the follower and/or the cam may comprise metal. Alternatively, the metal may be steel.

Optionally, the vehicle is a scooter or bicycle.

Optionally, the vehicle may include a handlebar connected to the fork by a steering gear.

Alternatively, the vehicle may include an electric motor for propelling the vehicle and a battery for supplying electric power to the electric motor.

Drawings

FIG. 1 is a side view of an exemplary scooter;

FIG. 2 is a cross-sectional view through a portion of the scooter;

FIG. 3 is a perspective view of a portion of the scooter with the fork of the scooter in a first position;

FIG. 4 is another perspective view of a portion of the scooter with the fork in a first position and the frame of the scooter omitted;

FIG. 5 is a perspective view of a portion of the scooter with the fork in a second position;

FIG. 6 is another perspective view of a portion of the scooter with the fork in a second position and the frame of the scooter omitted;

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FIG. 7 is a perspective view of a portion of an example of another scooter;

FIG. 8 is a cross-sectional view of a portion of another scooter.

Detailed Description

The scooter 10 of fig. 1 includes a frame 20, a pair of wheels 30, 35, and a steering assembly 40.

The frame 20 includes a head pipe 22, a down pipe 23 and a deck 24. A down tube 23 interconnects the head tube 22 and the deck 24. Deck 24 forms a platform upon which a user stands while using scooter 10.

The wheels include front wheels 30 and rear wheels 35. Each of the wheels 30, 35 comprises an axle 31, 36 about which the wheel rotates. The front wheels 30 are connected to the steering assembly 40 and the rear wheels 35 are connected to the deck 24.

Steering assembly 40 includes a handlebar 41, a steering gear 42, and a fork 43. A steering gear 42 interconnects the handlebar 41 and the fork 43. The fork 43 includes a steerer tube 44 and a pair of fork blades 45 or legs. Each fork tab 45 includes a missing portion (dropout) 46 for receiving the axle 31 of the front wheel 30. The fork 43 is fixedly connected to the steering gear 42 and rotatably connected to the head tube 22 of the frame 20. Thus, steering assembly 40 is free to rotate relative to frame 20.

Referring now to fig. 2, fork 43 is rotatably connected to head tube 22 of frame 20 by a pair of bearings 27, 28 and a compression system (not shown). The steerer tube 44 extends through the head tube 22 and the head tube 22 includes bearing blocks 25, 26 at each end of the head tube 22. Bearings 27, 28 are then located in each of the seats 25, 26. Then, a compression system (not shown) such as a Hidden Internal Compression (HIC), an Integrated Hidden Compression (IHC), or a Standard Compression System (SCS) is used to drive the bearings 27, 28 and the head tube 22 downward relative to the fork 43 so as to hold the head tube 22 and the bearings 27, 28 on the steering tube 44.

Fork 43 rotates relative to head tube 22 about axis of rotation 49. Thus, front wheel 30 can be steered side-to-side about rotational axis 49 using handlebar 41.

In use, when a user stands on deck 26 and turns using handlebar 41, scooter 10 is propelled forward. In this particular example, the scooter 10 is propelled by an electric motor 37 located in the hub of the rear wheel 35 and powered by a battery pack 38 located within the deck 24 of the scooter 10. However, the scooter 10 may be propelled in other ways as well. For example, the scooter 10 may be unpowered and propelled by a user.

During use, steering assembly 40 rotates relative to frame 20 in response to an input. This input may be provided by a user of the scooter 10. For example, the user may apply a steering force to handlebar 41, which in turn causes steering assembly 40 to rotate rightward or leftward (i.e., clockwise or counterclockwise) about axis of rotation 49. Or the input may be provided by an external force. For example, as the scooter 10 moves over the ground, bumps, dimples, and other uneven features on the ground may exert forces on the front wheels 30, thereby causing the steering assembly 40 to rotate relative to the frame 20. As another example, the front wheel 30 may exhibit hunting. Wheel wobble may be caused by a variety of causes, such as wheel imbalance, wheel bearing imperfections or problems, or wobble during braking. Wheel hunting may be particularly pronounced when the front wheel load is relatively light and/or when traveling at relatively high speeds. These external inputs to the steering assembly 40 may adversely affect the stability and control of the scooter 10. Thus, the scooter includes a self-centering mechanism 50 to help mitigate these effects and thus improve stability and control of the scooter 10.

Referring now to fig. 2-6, self-centering mechanism 50 includes cam 60, follower 70, and biasing member 80.

Cam 60 includes an annular sleeve or cannula fixedly attached to the inside of head tube 22. In this particular example, the cam 60 is a separate element that is connected to the head tube 22. In another example, cam 60 may form an integral part of head tube 22. The cam 60 includes a pair of rails 62 on opposite sides of the cam 60. Thus, the cam 60 includes a first track and a second track located on diametrically opposite sides of the cam 60. Only one rail 62 is visible in the figure due to the position of the rails. However, the two tracks are identical except for location. Each rail 62 has an inverted V-shaped profile and includes an inflection point 64 located in the middle of the rail and a pair of inclined portions 65 located on either side of the inflection point 64. Cam 60 also includes a stop 67 or end stop at each end of each track 62. The stop 67 is used to limit rotation of the follower 70 relative to the cam 60, as described in more detail below.

Follower 70 includes a body 72 and an elongated member 74. The body 72 is cylindrical or disc-shaped and is located within the steerer tube 44 of the fork 43. The body 72 includes a bore extending radially through a sidewall of the body 72. The elongate member 74 comprises a pin having bearings pressed against each end of the pin. The diameter of the pin is stepped and is smaller at the ends so that the elongate member has a substantially uniform diameter along its length. An elongate member 74 extends through an aperture in the body 72.

The steerer tube 44 includes a pair of slots 47, each extending in a direction parallel to the axis of rotation 49. The slots 47 are located on opposite sides of the fork 43 so that only one of the slots 47 is visible in the figure. Elongated member 74 of follower 70 then extends or protrudes through each of slots 47. The slot 47 is sized such that the elongate member 74 of the follower 70 rotates relative to the fork 43 about the axis of rotation 49, but is free to translate along the slot 47 in a direction parallel to the axis of rotation 49.

The biasing member 80 is located within the steerer tube 44 of the fork 43 and applies a biasing force to the follower 70. In this particular example, the biasing member 80 includes a coil spring, and more particularly includes a compression spring, that extends between the closed end of the steerer tube 44 and the body 72 of the follower 70. However, other forms of biasing members may be employed, such as tension springs, gas springs, or elastomers (e.g., elastomers made of rubber or other resilient materials).

The biasing member 80 biases the follower 70 relative to the cam 60. More specifically, biasing member 80 biases the end of elongate member 74 relative to track 62 of cam 60. Page 6/9 due to the contour or shape of the track 62

Like, the follower 70 is biased toward the inflection point 64 in the track 62. When the follower 70 is located at the inflection point 64, the follower 70 may be considered to be in a rest position or a stable position.

When the follower 70 is in the rest position, the fork 43 is aligned centrally (i.e., in a straight direction) with respect to the frame 20. Thus, when the follower 70 is in the rest position, the front wheel 30 is centered and the scooter 10 moves in a straight direction.

Fork 43 may move relative to frame 20 in response to an input force (e.g., a user moving handlebar 41, or an external force applied to front wheel 30). When fork 43 rotates relative to frame 20, follower 70 is caused to rotate relative to cam 60. Specifically, the steering tube 44 of the fork 43 engages an elongated member 74 of the follower 70 that extends through a slot 47 in the steering tube 44. Thus, when fork 43 is rotated, follower 70 is caused to rotate in the same direction about axis of rotation 49. As the follower 70 rotates about the rotational axis relative to the cam 60, the follower 70 moves along the track 62 of the cam 60. While moving along the track 62, the follower 70 moves away from the inflection point 64 and along the inclined portion 65 of the track 62. Thus, the follower 70 translates in a direction parallel to the axis of rotation 49 under the biasing force of the biasing member 80. More specifically, the body 72 of the follower 70 translates within the steerer tube 44 and the elongate member 74 translates along the slot 47 in the steerer tube 44. Thus, the follower 70 moves from the rest position under the biasing force of the biasing member 80.

When the input force on fork 43 is subsequently removed (e.g., if the user releases the force applied to handlebar 41 or removes the external force applied to front wheel 30), the biasing force applied by biasing member 80 returns follower 70 to the rest position. Specifically, the follower 70 is moved rearward along the track 62 in the cam 60 by the biasing member 80 until the follower 70 reaches and stabilizes at the inflection point 64. While moving along the track 62, the follower 70 rotates about the rotation axis 49 and translates parallel to the rotation axis 49. When rotated about the rotational axis 49, the follower 70 rotates the fork 43 relative to the frame 20. Thus, the follower 70 returns to the rest position, again centering the fork 43 with the frame 20. Thus, the self-centering mechanism 50 returns the fork 43 of the scooter 10, as well as the steering assembly 40 and the front wheels 30, to a centered position. Thus, stability and control of the scooter 10 may be improved.

Fig. 3 and 4 show a portion of scooter 10 with fork 43 in a centered position. Fig. 5 and 6 show the same portion of scooter 10, but with fork 43 rotated to the left. In fig. 4 and 6, frame 20 has been removed so that the components of self-centering mechanism 50 can be seen. As can be seen in fig. 4, when the fork 43 is in the center position, the follower 70 is located at the inflection point 64 in the track 62 (i.e., the follower 70 is in the rest position). In contrast, as seen in fig. 6, as fork 43 rotates to the left, follower 70 moves away from inflection point 64 and along sloped portion 65 of track 62. Upon moving along the inclined portion 65, the follower 70 translates downward under the biasing force of the biasing member 80.

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As described above, the cam 60 includes a stopper 67 at the end of each track 62. A stop 67 extends from the end of the rail 62 in a direction parallel to the axis of rotation 49. Further, the stop 67 is higher than the elongate member 74 of the follower 70 (i.e., the stop 67 extends beyond the elongate member 74 in a direction parallel to the rotational axis 49), which may prevent the follower 70 from riding over the stop 67. As fork 43 rotates relative to frame 20, follower 70 moves along track 62 of cam 60. Upon reaching the end of the track 62, the follower 70 engages the stop 67. The limiter 67 then prevents further rotation of the follower 70, so that further rotation of the fork 43 is not possible. Thus, the limiter 67 limits rotation of the follower 70 relative to the cam 60, thereby limiting rotation of the fork 43 relative to the frame 20. Accordingly, the steering angle of the steering assembly 40 is limited by the limiter 67. Thus, it is possible to prevent the steering angle from being too large, which may cause the bearings 27, 28 to be excessively loaded and cause safety problems during use. The limiter 67 may be considered to limit the steering angle of the steering assembly 40 to a predetermined angle range. In this example, the predetermined angular range is approximately 45 degrees in either direction from the center position (i.e., the follower 70 may freely rotate 45 degrees in either direction from the inflection point 64). Thus, the front wheel 30 of the scooter 10 may be rotated or turned 45 degrees in either direction. The stop 67 of the cam 60 may be omitted or omitted and the steering angle of the steering assembly 40 may be limited in other ways, if desired. For example, the head tube 22 and the steer tube 44 may include features that limit the steer angle.

The elongated member 74 of the follower 70 includes bearings at each end of the pin. As the follower 70 moves over the cam 60, each bearing then rotates (about an axis perpendicular to the axis of rotation 49). The provision of bearings reduces wear of the cam 60 and follower 70. However, it is contemplated that the bearings may be omitted or replaced with other rotatable portions (e.g., a sleeve or bushing that rotates freely over the pin). In the case where elongate member 74 does not include bearings or rotatable portions, elongate member 74 as a whole may rotate as it moves along track 62. Or elongate member 74 may slide along track 62 rather than rotate. The body 72 of the follower 70 simplifies assembly of the self-centering mechanism 50 (as described below) and also helps ensure that the biasing force exerted by the biasing member 80 on the follower 70 is evenly distributed. However, it is contemplated that the body 72 may be omitted and the biasing member 80 may act directly on the elongate member 74.

The track 62 of the cam 60 has a V-shaped profile. Thus, the slope of the track 62 is constant on either side of the inflection point 64. Accordingly, the biasing force acting on the follower 70 increases linearly with the rotation of the follower 70 and the fork 43. The track 62 of the cam 60 may also have other profiles to achieve different responses. For example, the cam tracks 62 may have a U-shaped profile such that the slope of each track 62 increases as the follower 70 moves from the inflection point 64.

To assemble the scooter 10, and in particular the assembly shown in fig. 2, the lower bearing 27 is inserted onto the steerer tube 44 of the fork 43. Then, a biasing member 80 (e.g., a compression spring) is inserted into the steerer tube 44. The body 72 of the follower 70 is then placed on top of the biasing member 80 and pressed downwardly into the steerer tube 44 under the biasing force of the biasing member 80. The body 72 of the follower 70 is pressed downwardly until the body 72 is aligned with the slot 47 in the steerer tube 44. The elongate member 74 is then inserted through the slot 47 in the steerer tube 44 and into the bore of the body 72. The body 72 of the follower 70 is then released, causing the biasing member 80 to bias the follower 70 upward until the elongate member 74 abuts the top of the slot 47 in the steerer tube 44. The subassembly of fork 43, lower bearing 27, follower 70 and biasing member 80 is then inserted into head tube 22. The lower bearing 27 is mounted in the lower seat 25 of the head tube 22 and the elongate member 74 of the follower 70 engages the track 62 of the cam 60 which is connected to the inside of the head tube 22. Finally, the upper bearing 28 is inserted onto the steerer tube 44 and mounted in the upper seat 28 of the head tube 22 to provide the assembly shown in fig. 2.

Fig. 7 and 8 illustrate another example of a scooter 100. The corresponding features are increased by 100, but are not discussed in further detail.

In this other example, the components of self-centering mechanism 150 are substantially unchanged, but their arrangement within head tube 122 and fork 143 is reversed. As with the previous example, self-centering mechanism 150 includes cam 160, follower 170, and biasing member 180 (again in the form of a compression spring). Likewise, cam 160 is connected to the inside of head tube 122, and follower 143 includes an elongated member 174 that extends through a slot 147 in steering tube 144 of fork 143, while biasing member 180 is located within steering tube 144. In contrast to the above examples, the follower 143 does not include a body other than the elongate member 174. Instead, self-centering mechanism 150 includes a spacer 182 or washer between biasing member 180 and follower 170 to more evenly distribute the biasing force across follower 170. Due to the inversion of the components of self-centering mechanism 150, biasing member 180 now biases follower 170 downward rather than upward, and inflection point 164 in each of tracks 162 of cam 160 corresponds to the lowest point in tracks 162 rather than the highest point. In all other aspects, the components of self-centering mechanism 150 remain unchanged. For example, cam 160 continues to include track 162 along which follower 170 moves during rotation of follower 170 relative to cam 160. Each of the tracks 162 includes a center inflection point 164 that corresponds to a resting position to which the follower 170 is biased by the biasing member 180.

To assemble the scooter 100 of this further example, the lower bearing 127 and the upper bearing 128 are mounted within the head tube 122. The steerer tube 144 of the fork 143 is then inserted through the bearings 127, 128 and head tube 122. In contrast to the above example, the head pipe 122 of this other example includes a small insertion hole 129 through which the follower 170 is inserted. To insert follower 170, fork 143 is moved to a centered position relative to head tube 122. This will then align the slot 147 in the steerer tube 144 with the insertion aperture 129. The follower 170 is then inserted through the insertion hole 129 and inserted through the slot 147 in the steerer tube 144. When fully inserted, the follower 170 falls onto the track of the cam 160 and into the rest position. A spacer 182 and a biasing member 180 (e.g., a compression spring) are then inserted into the steerer tube 144. Finally, when the compression system of scooter 100 is coupled to steering tube 144 (compression ring 192 and bolts 194 of the compression system are shown in fig. 7 and 8), bolts or fasteners 194 of the compression system compress biasing member 180 within steering tube 144. Accordingly, the biasing member 180 applies a biasing force to the follower 170.

In each of the above examples, the cams 60, 160 are fixedly connected to the head pipe 22, 122 and the followers 70, 170 rotate with the forks 43, 143. In other examples, the follower may be fixedly connected to (or integrally formed with) the head tube, and the cam may rotate with the fork. For example, the follower may include one or more protrusions protruding radially inward from the head tube, and the cam may include a body surrounding at least a portion of the steerer tube of the fork. The cam may then be configured such that the cam rotates with the steering tube about the axis of rotation, but may translate freely up and down in a direction parallel to the axis of rotation. For example, the steering tube may also include one or more grooves extending parallel to the axis of rotation, and the cam may include one or more protrusions protruding into the grooves. The cam is then free to translate the slot up and down, while rotation of the steerer tube rotates the cam. In this example, the biasing member may include a spring that surrounds the steerer tube and extends between the cam and one of the two bearings.

In the above example, the self-centering mechanism 50, 150 is fully housed within the frame 20, 120 of the scooter, in particular within the head tube 22, 122. Thus, the self-centering mechanism 50, 150 does not adversely affect the aesthetics of the scooter 10, 100. Furthermore, the self-centering mechanism 50, 150 is protected from dirt, water, etc., that may be thrown from the ground. Thus, the robustness and lifetime of the self-steering mechanism 50, 150 may be improved.

In the above examples, a self-centering mechanism is employed in a scooter. Because the wheels of the scooter are relatively small, external forces acting on the front wheels may have a significant impact on the stability and control of the scooter. Therefore, it is particularly advantageous to include a self-centering mechanism in a scooter, particularly an electric scooter capable of traveling at relatively high speeds. However, the self-centering mechanism described herein may be used with other vehicles for centering the position of the wheel. For example, the self-centering mechanism may be used with a bicycle. In another example, a self-centering mechanism may be used to center the position of the casters of the vehicle.

It should be understood that any feature described in relation to any one example may be used alone, in combination with other features described, and may also be used with one or more features of any other of the examples, or any combination of any other of the examples. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.

Claims (25)

1. A vehicle, the vehicle comprising:

a frame;

a fork arranged to rotate relative to the frame about an axis of rotation;

a wheel connected to the fork; and

A self-centering mechanism for centering a position of the wheel, the self-centering mechanism comprising:

The cam is provided with a cam which is provided with a cam,

A follower engaged with the cam; and

A biasing member for biasing the follower relative to the cam,

Wherein:

Rotation of the fork relative to the frame rotates the follower relative to the cam about the axis of rotation; and

The cam is shaped such that the follower is biased to a rest position by the biasing member and rotation of the follower relative to the cam moves the follower from the rest position and translates relative to the cam in a direction parallel to the axis of rotation under the influence of the biasing member.

2. The vehicle of claim 1, wherein the follower comprises an elongated member engaged with the cam.

3. The vehicle of claim 2, wherein the elongated member has a longitudinal axis perpendicular to the axis of rotation.

4. A vehicle according to claim 2 or 3, wherein a first end of the elongate member is engaged with a first portion of the cam and a second end of the elongate member is engaged with a second portion of the cam.

5. A vehicle according to any preceding claim, wherein the follower comprises a rotatable portion engaged with the cam and the rotatable portion is arranged to rotate about an axis perpendicular to the axis of rotation.

6. A vehicle according to any preceding claim, wherein the follower comprises a first rotatable portion engaged with a first portion of the cam and a second rotatable portion engaged with a second portion of the cam, wherein each of the first and second rotatable portions is arranged to rotate about a respective axis perpendicular to the axis of rotation.

7. A vehicle according to claim 5 or 6, wherein the or each rotatable portion comprises a bearing.

8. A vehicle according to any preceding claim, wherein the follower is arranged to translate relative to the cam within a slot for guiding translation of the follower relative to the cam.

9. The vehicle of claim 8, wherein the fork includes the slot.

10. The vehicle of claim 8 or 9, wherein the slot is linear and extends parallel to the axis of rotation.

11. The vehicle of any of the preceding claims, wherein the cam includes a track having an inflection point, the follower engaging and moving along the track when the follower rotates relative to the cam, the biasing member biasing the follower relative to the track toward the inflection point, and the follower being in the rest position when the follower is located at the inflection point.

12. The vehicle of claim 11, wherein the track comprises a first track and a second track, each track engaging a respective portion of the follower.

13. The vehicle of claim 12, wherein the first track is radially opposite the second track relative to the axis of rotation.

14. The vehicle of claim 12 or 13, wherein the first rail and the second rail are different such that during rotation of the follower relative to the cam, a respective portion of the follower is engaged with only one of the first rail or the second rail by the biasing member.

15. A vehicle as claimed in any one of claims 11 to 14, wherein the or each track comprises a V-shaped or U-shaped profile.

16. A vehicle according to any preceding claim, wherein the cam includes a limiter to limit rotation of the follower relative to the cam to a predetermined angle of rotation.

17. A vehicle according to any preceding claim, wherein the cam is annular.

18. A vehicle according to any preceding claim, wherein the biasing member is located within the fork.

19. A vehicle according to any preceding claim, wherein the biasing member comprises a coil spring.

20. A vehicle according to any preceding claim, wherein the biasing member is arranged to expand and contract in a direction parallel to the axis of rotation in response to movement of the follower relative to the cam.

21. A vehicle according to any preceding claim, wherein the cam surrounds the biasing member.

22. A vehicle according to any preceding claim, wherein the follower comprises a body movable within a tube of the fork.

23. A vehicle according to any preceding claim, wherein the cam is connected to the inside of the head tube of the frame.

24. The vehicle of any one of the preceding claims, wherein the vehicle comprises a bicycle or scooter.

25. The vehicle of claim 24, wherein the vehicle includes a handlebar connected to the fork by a steering gear.