JP2009083539A - Rear-wheel drive four-wheel bicycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rear-wheel drive four-wheel bicycle capable turning in a small circle by improving maneuvering stability at turning. <P>SOLUTION: This rear-wheel drive four-wheel bicycle 1 is provided by forming a steering part 3 arranged in an intermediate part in the longitudinal direction, a loading part 4 capable of placing a placing object with front wheels 12 and 12 arranged in front of the steering part 3 and arranged at both sides, a saddle 5 which is arranged in the rear of the steering part 3 and on which a driver gets, a rear wheel device 6 including a rear wheel receiving frame 24 having a rear wheel steering shaft 23 for steering and turning a bearing 22 by extending upward from the bearing 22 pivoting a rear wheel shaft 21 arranged in the rear of the saddle part 5 and connecting a pair of rear wheels 20 and 20, a driving means 7 rotating the rear wheels 20 and 20 via a gear means 44 arranged in the rear wheel receiving frame 24 by the rotation of a pedal 43, and a steering linking means 8 for steering the rear wheels 20 and 20 by turning the rear wheel steering shaft 23 in conjunction with a handle 31 arranged in the steering part 3 in a main frame 2. The steering linking means 8 steers and turns by exceeding 360 degrees in angle while rotating the rear wheels 20 and 20 by the driving means 7. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

    The present invention relates to a rear-wheel drive four-wheel bicycle having rear wheels as drive wheels and steering wheels.

  In Patent Document 1 below, a four-wheeled bicycle is provided with a loading platform on which a heavy object, an occupant, or the like is placed on the front wheel side of the vehicle body, and the front wheel is driven by a pedal, and the rear wheel is a steering wheel operated by a steering wheel. Has been proposed.

Noto 3007093

  In such a four-wheeled bicycle, the rear wheel is a steered wheel, so the front wheel side is not swung to the right or left at the time of steering. Therefore, it is possible to stabilize the load and people placed on the front wheel side loading platform. Can carry. However, since the front wheels become drive wheels and are pulled in the straight direction, there is a problem that the course taking by the rear wheel steering becomes unstable, and the turning performance and the steering stability are poor. In particular, when a person or a heavy object is placed on the front wheel side loading platform, the load is biased toward the front wheel side, making it difficult to steer by the rear wheels, and the deterioration in turning performance and steering stability becomes more remarkable.

  The four-wheel bicycle has a large turning radius when turning because the steering angle of the rear wheel is limited. For this reason, although it is possible to make a small turn, it is inadequate. For example, it is difficult to smoothly and easily perform turning in a narrow place and width adjustment at the time of parking.

  The present invention has been devised in view of the above situation, and is based on the concept of rear wheel drive and rear wheel steering, and capable of steering turning beyond 360 degrees while driving the rear wheels. The main purpose is to provide a rear-wheel drive four-wheeled bicycle that improves turning performance and steering stability and enables smaller turning.

In order to achieve the above-mentioned object, the invention of claim 1 of the present application has a steering unit disposed in an intermediate portion in the front-rear direction, and a front wheel provided in front of the steering unit and disposed on both sides. A loading portion that can be placed; a saddle portion that is provided behind the steering portion and on which an operator is placed; and a bearing portion that is provided behind the saddle portion and pivotally supports a rear wheel shaft that connects a pair of rear wheels. A rear wheel device including a rear wheel steering shaft portion for steering and turning the bearing portion and a rear wheel receiving frame for holding the rear wheel steering shaft portion, via gear means provided on the rear wheel receiving frame by rotation of a pedal A rear-wheel drive four-wheel bicycle in which a driving means for rotating the rear wheels and a steering linkage means for steering the rear wheels by turning the rear-wheel steering shaft portion linked to a handle provided in the steering portion are formed on the main frame. Because
The steering linkage means is characterized in that the rear wheels are steered over 360 degrees while being rotated by the driving means.

  According to a second aspect of the present invention, the steering linkage means includes endless linkage means for rotatably connecting a handle shaft extending from the handle and a steering intermediate shaft provided on the side of the rear wheel receiving frame, and The steering intermediate shaft is provided with a reverse transmission means for rotating in the reverse direction, and the rear wheel steering shaft portion is turned and steered.

  According to a third aspect of the present invention, the drive means includes an endless linkage that links a crankshaft provided with the pedal and a horizontal drive shaft provided on the rear wheel receiving frame, and the gear means includes A first bevel gear provided on the drive shaft, and a second bevel gear provided on an upper end of a drive cylinder that meshes with the first bevel gear and is rotatably inserted on the rear wheel steering shaft. And a third bevel gear provided at the lower end portion of the drive cylinder, and a fourth bevel gear meshed with the third bevel gear and provided on the rear wheel shaft.

  According to a fourth aspect of the present invention, the driving means includes a one-way clutch that allows reverse rotation of the pedal.

  According to a fifth aspect of the present invention, the rear wheel steering shaft portion has a caster angle of 3 to 20 degrees with respect to a vertical line, and a lower end thereof is inclined forward.

  In the rear-wheel drive four-wheel bicycle according to the present invention, as described above, the rear wheel also serves as a drive wheel and a steering wheel. Therefore, the front wheel side is not swung to the left and right during steering, and it is driven directly in the steering direction while demonstrating the advantages of rear wheel steering that enables stable transportation of luggage and people placed on the front wheel side loading platform. Therefore, the turning performance and steering stability can be improved.

  Moreover, the rear wheels can steer over 360 degrees. Therefore, the rear-wheel drive four-wheel bicycle can be easily changed in direction, for example, by enabling a small turn with the front wheel as the turning center, that is, with a minimum turning radius. For this reason, for example, turning in a narrow place and width adjustment at the time of parking can be performed smoothly and easily.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view of a rear-wheel drive four-wheel bicycle (hereinafter sometimes simply referred to as “four-wheel bicycle”) of the present embodiment, FIG. 2 is a front view thereof, and FIG. 3 is a plan view thereof. .

  As shown in FIGS. 1 to 3, the rear-wheel drive four-wheel bicycle 1 includes a steering unit 3 disposed in an intermediate part in the front-rear direction, a loading unit 4 provided in front of the steering unit 3, and the steering A saddle part 5 provided behind the part 3, a rear wheel device 6 provided behind the saddle part 5, a driving means 7 for rotating the rear wheel 20, and a steering linkage means 8 for steering the rear wheel 20. It is formed on the main frame 2.

  The main frame 2 is formed in a rod shape extending rearward with a gentle upward slope along the width center line of the stacking portion 4. The stacking portion 4 has a base frame 4A having a wide rectangular frame shape, for example, fixed to the front end of the main frame 2, and front wheels 12 and 12 are attached to the front end side and both sides of the base frame 4A. In the present example, the front wheels 12 and 12 are pivotally attached independently of each other. Therefore, when the four-wheel bicycle 1 turns, the rolling distance between the front wheel 12 outside the turn and the front wheel 12 inside the turn. Can be absorbed, and smooth turning without slipping can be performed. The front wheels 12, 12 are respectively attached to the base frame 4A via dampers 13 that absorb and mitigate shocks from the road surface.

  Further, in this example, the stacking portion 4 includes a base plate 4B disposed on the base frame 4A, and a seat portion 4C with an armrest that is disposed further above the base plate 4B and on which an occupant can sit. The case of including is illustrated. Since the base frame 4A is formed of a wide rectangular frame body, the seat portion 14 can secure a relatively large width and can stably place an occupant. The base plate 4B can be used as a step base or a footrest for passengers to get on and off. However, the loading unit 4 is not limited to such a mode, and instead of the seat unit 14, for example, it is formed as a bed (illustration omitted) for carrying a sick person, a loading platform (illustration omitted) or the like for loading a load. You can also Furthermore, the stacking unit 4 can be configured only by providing the base plate 4B on the base frame 4A.

  Next, the saddle portion 5 includes a saddle 15 on which an operator (driver) is mounted, a rod-shaped saddle post 16 extending downward from the saddle 15, and a vertical cylindrical saddle post fixed to the main frame 2. And mounting portion 17. The saddle post 16 has a lower end inserted into the saddle post mounting portion 17, and the height position of the saddle 15 can be adjusted according to the depth of insertion. The saddle post mounting portion 17 can fix the height position of the saddle post 16 by a screw-type fastener 18 provided at the upper end thereof.

  Next, as shown in FIG. 6, the rear wheel device 6 includes a pair of rear wheels 20, 20, a rear wheel shaft 21 that joins the pair of rear wheels 20, 20, and a bearing that pivotally supports the rear wheel shaft 21. Part 22, a rear wheel steering shaft part 23 for steering and turning the bearing part 22 upward from the bearing part 22, and fixed to the main frame 2 and holding the rear wheel steering shaft part 23 for steering rotation. A rear wheel receiving frame 24 (shown in FIGS. 4 and 5) is provided.

  A pair of said rear wheels 20 and 20 is fixed to the said rear-wheel axis | shaft 21 through the tire wheel 20a (shown in FIG. 5), respectively, so that integral rotation is possible. That is, the rear wheel shaft 21 and the rear wheels 20 and 20 rotate as one body without the rear wheels 20 rotating independently of each other. The rear wheel shaft 21 is rotatably supported by a bearing bearing 26 (shown in FIG. 5) built in the bearing portion 22.

  Further, in the pair of rear wheels 20 and 20, if the wheel interval L (shown in FIG. 2) between the tire equator is too narrow, the left and right stability is deteriorated. Since the difference in rotational speed between the rear wheel 20 and the inner rear wheel 20 becomes large, the steering performance becomes unstable, and it is disadvantageous for a small turn. From the above viewpoint, the wheel interval L has a lower limit value of 50 mm or more, more preferably 70 mm or more, and an upper limit value of 200 mm or less, more preferably 150 mm or less.

  The rear wheel steering shaft portion 23 is pivotally supported by a bearing bearing 29 (shown in FIG. 5) extending upward from the bearing portion 22 and provided on the rear wheel receiving frame 24. As a result, the rear wheel steering shaft portion 23 can integrally rotate with the bearing portion 22 to rotate the bearing portion 22 in a horizontal direction (steer turn) beyond 360 degrees (one rotation). In this example, the rear wheel steering shaft portion 23 is held so as to be freely rotatable in forward and reverse directions over a number of times. A spur gear-like rear wheel steering shaft gear 30 is provided at the upper end of the rear wheel steering shaft portion 23.

  In this example, the rear wheel steering shaft portion 23 has a caster angle θ (shown in FIG. 4) of 3 to 20 degrees with respect to the vertical line, and a lower end 23d thereof is inclined forward. Thereby, in the pair of rear wheels 20 and 20 supported at both ends of the rear wheel shaft 21, the rear wheel 20 outside the turn is lifted from the road surface by the steering rotation of the rear wheel steering shaft portion 23 during turning. Can do. That is, only the rear wheel 20 on the inside of the turn comes to ground. As a result, the rear wheel 20 on the outside of the turn does not generate a slip with the ground contact surface at the time of turning, and smooth and stable cornering can be performed. When the caster angle θ is less than 3 degrees, the above effect cannot be expected. On the other hand, when the caster angle θ exceeds 20 degrees, the lift amount of the rear wheel 20 on the outside of the turn becomes excessive, which impairs the balance of the bicycle. Fear arises. From the above viewpoint, the caster angle θ is more preferably 5 degrees or more, more preferably 7 degrees or more as a lower limit value, and more preferably 12 degrees or less, and even more preferably 10 degrees or less as an upper limit value.

  Next, as shown in FIG. 1, the steering unit 3 pivotally supports the handle 31 gripped by the operator, the handle shaft 32 extending downward from the handle 31, and the handle shaft 32 so as to be rotatable therebelow. A handle shaft attaching portion 33.

  In the present embodiment, the handle 31 is formed in a substantially U-shape in which a grip portion 31a that an operator grips and operates is directed upward. With such a shape, for example, even if the operator rotates the handle 31 beyond 360 °, the grip portion 31a always passes on a circular arc with a constant radius, so the operator needs to change the posture. The handle can be easily operated.

  The handle shaft 32 extends downward from the handle 31, and a lower end portion of the handle shaft 32 is inserted into a vertical cylindrical handle shaft mounting portion 33 fixed to the main frame 2, and is pivotally supported. A handle shaft sprocket 35 is fixed to the handle shaft 32 at a position above the handle shaft mounting portion 33 so as to be concentric with the handle shaft 32 and integrally rotatable. Therefore, as shown in FIG. 6, when the handle 31 is steered in the direction of the arrow R <b> 1, for example, the handle shaft sprocket 35 can rotate integrally with the handle 31.

  Next, as shown in FIG. 6, the steering linkage means 8 is linked to the handle 31 and turns the rear wheel steering shaft portion 23 to steer the rear wheel 20. Specifically, the steering linkage means 8 includes a steering intermediate shaft 36 that is attached to the rear wheel receiving frame 24, and endless linkage means 37 that rotatably connects the handle shaft 32 and the steering intermediate shaft 36. Further, the rear wheel 20 can be steered over 360 degrees while being rotated by the driving means 7.

  The steering intermediate shaft 36 is held on the rear wheel receiving frame 24 so as to be positioned in front of the rear wheel steering shaft portion 23 and in parallel with the rear wheel steering shaft portion 23. The steering intermediate shaft 36 is rotatably supported on the rear wheel receiving frame 24 via a bearing (not shown), and a steering intermediate shaft sprocket is provided at one end (in this example, the lower end). 42 is fixed concentrically and integrally rotatable.

  The endless link means 37 includes the handle shaft sprocket 35, a steering intermediate shaft sprocket 42, and a steering endless link 37a such as a chain wound around the sprockets 35 and 42 so as to be able to circulate. In this example, the handle shaft sprocket 35 and the steering intermediate shaft sprocket 42 have the same number of teeth, and therefore the endless linking means 37 has the same steering intermediate shaft 36 as the same angle as the handle 31. Can be rotated in the direction. As a matter of course, a toothed belt can also be used as the steering endless string 37a. In such a case, instead of the handle shaft sprocket 35 and the steering intermediate shaft sprocket 42, the toothed belt may be used. A meshing belt pulley is used.

  A spur-gear-shaped steering intermediate shaft gear 40 that meshes with the rear wheel steering shaft gear 30 is fixed to the steering intermediate shaft 36 at the upper end thereof so as to be concentric with the steering intermediate shaft 36 and integrally rotatable. That is, the steering intermediate shaft 36 is connected to the rear wheel steering shaft portion 23 so as to be rotatable in the opposite direction by the gears 30 and 40 meshing with each other. That is, the reverse transmission means 38 is constituted by the gears 30 and 40, and the steering intermediate shaft 36 rotates the rear wheel steering shaft portion 23 by interposing the reverse transmission means 38 that rotates in the reverse direction. Can steer. In this example, the steering intermediate shaft gear 40 and the rear wheel steering shaft gear 30 have the same number of teeth. Therefore, the steering linking means 8 has the same angle as that of the handle 31 and the rear wheel steering shaft portion 23. Can be rotated in the reverse direction R2.

  Next, as shown in FIG. 7, the driving means 7 rotationally drives the rear wheels 20, 20 through the gear means 44 provided on the rear wheel receiving frame 24 by the rotation of the pedal 43 by the operator. . Specifically, the drive means 7 includes an endless string 47 that links a crankshaft 45 provided with the pedal 43 and a horizontal drive shaft 46 provided on the rear wheel receiving frame 24.

  The crankshaft 45 is pivotally supported by the main frame 2, and a chain ring 49 is attached to the crankshaft 45 so as to be concentric and integrally rotatable.

  The drive shaft 46 projects horizontally from the rear wheel receiving frame 24 (shown in FIG. 4), and a drive shaft sprocket 51 is concentrically and rotatably mounted on the drive shaft 46. Further, between the drive shaft sprocket 51 and the chain ring 49, an endless continuous string 47 as a chain is wound so as to be able to go around. Accordingly, the drive shaft sprocket 51 is rotationally driven in the same direction as the crankshaft 45 by a pedal operation by the operator. Reference numeral 52 in the figure denotes a tension sprocket that stretches the endless string 47. As a matter of course, a toothed belt can also be used as the endless string 47. In this case, instead of the chain ring 49 and the drive shaft sprocket 51, a belt pulley that meshes with the toothed belt is provided. used. In this example, a one-way clutch (not shown) that allows reverse rotation of the pedal 43 is built in the drive shaft sprocket 51. Therefore, as in the case of a conventional two-wheeled bicycle, only the forward drive rotation from the crankshaft 45 is transmitted to the rear wheel 20, so that it can be idle with respect to the reverse drive rotation. In other words, since the input from the tire side to the crankshaft side is cut off, coasting can be performed and, for example, traveling safety on a downhill can be improved. The one-way clutch may be built in the chain ring 49.

  As shown in FIGS. 5 and 7, the gear means 44 meshes with a first bevel gear 44 a provided on the drive shaft 46 and the first bevel gear 44 a, and is rotatable about the rear wheel steering shaft portion 23. The second bevel gear 44b provided at the upper end of the drive cylinder 53 to be externally inserted, the third bevel gear 44c provided at the lower end of the drive cylinder 53, the third bevel gear 44c meshing with the third bevel gear 44c and the And a fourth bevel gear 44 d provided on the rear wheel shaft 21. The first bevel gear 44a is integrally connected to the drive shaft sprocket 51 so as to be concentric with each other and integrally rotatable.

  The drive cylinder 53 is positioned on the lower side of the rear wheel receiving frame 24 and is rotatably held on the rear wheel steering shaft portion 23. The second bevel gear 44b and the third bevel gear 44c are attached to the upper end portion and the lower end portion of the drive cylinder 53 so as to be concentric with the drive cylinder 53 and integrally rotatable. The fourth bevel gear 44d is attached to the rear wheel shaft 21 so as to be concentric with the rear wheel shaft 21 and integrally rotatable. In this example, the case where the fourth bevel gear 44d is fixed to the rear wheel shaft 21 via the tire wheel 20a so as to be integrally rotatable is illustrated.

  Since the gear means 44 is configured in this way, as shown in FIG. 7, the driving force D by the operator's pedal operation is the crankshaft 45 → the chain ring 49 → the endless string 47 → the driving shaft sprocket 51 → the first umbrella. The gear 44a, the second bevel gear 44b, the drive cylinder 53, the third bevel gear 44c, the fourth bevel gear 44d, and the rear wheel shaft 21 are sequentially transmitted. At this time, since the drive cylinder 53 is rotatably held on the rear wheel steering shaft portion 23, the drive cylinder 53 is driven without being affected by the steering rotation of the rear wheel steering shaft portion 23 by the steering operation. The cylinder 53 can rotate freely. That is, the driving force D by the pedal operation is transmitted to the rear wheel shaft 21 independently without being influenced by the steering rotation by the steering wheel operation, so that the steering turn exceeding 360 degrees while rotating the rear wheel 20 is performed. Can be performed.

  As shown in FIG. 4, the drive means 7 is provided with a disk brake 62 comprising a disk-shaped disk rotor 62a and a brake caliper 62b having a brake pad.

  In this example, the disk rotor 62a is fixed to the second bevel gear 44b so as to be concentric and integrally rotatable as shown in FIG. The brake caliper 62b is attached to the rear wheel receiving frame 24 or the main frame 2, and the brake pad sandwiches the disc rotor 62a from both sides so that a braking force can be applied. The disc brake 62 can be operated by operating the brake lever 31b disposed on the handle 31. The braking means is not limited to the disc brake 62, and various known structures can be employed.

  Thus, since the rear wheel drive four-wheel bicycle 1 uses the rear wheel 20 as a steering wheel, the front wheel side is not swung to the left and right at the time of steering. Can be carried stably. In addition, the rear wheel 20 as the steered wheel is driven and can be moved while being driven directly in the steering direction, so that the steering performance is excellent, the turning performance and the steering stability are improved, and the precision such as a slight width adjustment is obtained. High driving operation can be performed easily. Further, since the pair of rear wheels 20 and 20 arranged in parallel are driven on the road surface with the same rotational force, for example, even when a heavy object is placed on the stacking portion 4, the grip force of the rear wheel 20 can be sufficiently secured. In addition to driving performance when going straight, it can exhibit excellent turning performance and steering stability. Therefore, in particular, it can be suitably employed as a low-speed bicycle for nursing care that carries elderly people, disabled people, and the like.

  As shown in FIG. 8 (A), for example, when the rear-wheel drive four-wheel bicycle 1 starts in a straight traveling state, the pair of rear wheels 20 contacts the road surface to ensure gripping force. It is possible to go straight (arrow E1) without running, and to maintain stable steering performance throughout the subsequent running. Further, even when one of the rear wheels 20 is punctured, the other rear wheel 20 can function as a drive steering wheel, so that traveling can be continued while preventing overturning, thereby improving traveling safety.

  As shown in FIG. 8B, for example, when the handle 31 is rotated to the right (arrow H2), the rear wheels 20 and 20 are rotated to the left (arrow T2). Thereby, the said rear-wheel drive four-wheel bicycle 1 can turn right (arrow E2). As described above, the vehicle can be turned by a steering operation similar to that of a conventional bicycle, and therefore, it is possible to easily drive without feeling uncomfortable in the steering feeling.

  As shown in FIG. 8C, for example, when the handle 31 is rotated 90 degrees to the right (arrow H3), the rear wheels 20, 20 are rotated 90 degrees to the left (arrow T3). In this state, the rear wheel drive four-wheel bicycle 1 can rotate around the front wheel 12 on the inner side of the turn by turning the pedal 43 (arrow E3). That is, the rear-wheel drive four-wheel bicycle 1 can turn around with a minimum turning radius.

  As shown in FIG. 8D, when the handle 31 is rotated by 180 degrees (arrow H4), the rear wheels 20 and 20 are also rotated by 180 degrees (arrow T4). At this time, since the rear wheels 20 and 20 are rotated rearward by the rotational drive by the pedal 43, the rear wheel drive four-wheel bicycle 1 can be moved backward (arrow E4). Therefore, even if the vehicle enters a narrow space such as an elevator from the front, it can be easily moved backward in the same posture without getting off the rear wheel drive four-wheel bicycle 1 by turning the handle 31 by 180 degrees. Can do.

  FIG. 9 illustrates another embodiment. In this example, the handle shaft 32 is inserted into the handle shaft mounting portion 33 and rotatably supported by a lower handle shaft portion 32a, and the lower handle shaft portion 32a is connected to the front and rear via a universal joint 60. The upper handle shaft portion 32u is connected to the upper handle shaft portion 32u so as to be bent, and is supported by the bending posture adjusting tool 61 in a desired bending posture. The bending posture adjuster 61 includes a fan-shaped support plate 61d having a circular guide hole 61c centered on the bending point of the handle shaft 32 and fixed to the handle shaft mounting portion 33 or the main frame 2 or the like. Prepare. A screw-type stopper 61b passing through the guide hole 61c is screwed to the upper handle shaft portion 32u, whereby the upper handle shaft portion 32u is fixed in a desired bending posture. In this way, in this example, the upper handle shaft portion 32u can be adjusted to an optimal bending posture according to the physique, sex, etc. of the operator. Is preferable.

  In this example, the handle 31 is exemplified by a ring shape. Such a ring-shaped handle 31 has an advantage that it is excellent in operability as compared with a substantially U-shaped handle when it is rotated by 360 ° or more. In particular, when used together with the universal joint 60, the distance from the operator is constant, so that the operability can be further improved.

  As described above, the particularly preferred embodiment of the present invention has been described in detail. However, the rear-wheel drive four-wheel bicycle 1 of the present invention can be attached to the drive means 7 with an electric motor that assists the rotation of the pedal 43, The present invention is not limited to the illustrated embodiment, and various modifications can be made.

It is a side view of the rear-wheel drive four-wheel bicycle of this embodiment. It is the front view. FIG. It is the principal part enlarged view. It is the AA cross-sectional arrow view. It is a fragmentary perspective view explaining a steering means and a steering linkage means. It is a fragmentary perspective view explaining a drive means and a gear means. (A) is a schematic plan view for explaining a straight traveling state, (B) is a schematic plan view for explaining a state of turning at an angle close to 45 °, and (C) is for explaining a state of turning about a front wheel as a substantial center. (D) is a schematic plan view for explaining the retracted state. It is a partial side view which shows another Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rear wheel drive four-wheel bicycle 2 Main frame 3 Steering part 4 Loading part 5 Saddle part 6 Rear wheel device 7 Drive means 8 Steering linkage means 12 Front wheel 20 Rear wheel 21 Rear wheel shaft 22 Bearing part 23 Rear wheel steering shaft part 24 Rear Wheel receiving frame 43 Pedal 44 Gear means

Claims (5)

Steering part arranged in the middle part in the front-rear direction, a loading part provided in front of this steering part and having front wheels arranged on both sides and capable of placing a mounted body, an operator provided behind the steering part A rear wheel steering shaft portion that is provided behind the saddle portion and that pivots upward from a bearing portion that pivotally supports a rear wheel shaft that joins a pair of rear wheels and that steers the bearing portion, and the rear wheel A rear wheel device including a rear wheel receiving frame for holding a steering shaft portion, a driving means for rotating a rear wheel via a gear means provided on the rear wheel receiving frame by rotation of a pedal, and a handle provided on the steering portion A rear-wheel drive four-wheel bicycle in which a main frame is provided with steering linkage means for steering the rear wheel by turning the rear wheel steering shaft portion.
The rear-wheel-drive four-wheel bicycle, wherein the steering linkage means steers and turns a rear wheel beyond 360 degrees while being rotated by the driving means.   The steering linkage means has endless linkage means for rotatably connecting a handle shaft extending from the handle and a steering intermediate shaft provided on the rear wheel receiving frame, and the steering intermediate shaft rotates in a reverse direction. The rear-wheel drive four-wheel bicycle according to claim 1, wherein the rear-wheel steering shaft portion is turned and steered through a reverse transmission means.   The drive means includes an endless linkage that links a crankshaft provided with the pedal and a horizontal drive shaft provided on the rear wheel receiving frame, and the gear means includes a first shaft provided on the drive shaft. A first bevel gear, a second bevel gear provided at the upper end of a drive cylinder that meshes with the first bevel gear and is rotatably inserted on the rear wheel steering shaft, and a lower end of the drive cylinder The rear-wheel-drive four-wheel bicycle according to claim 1 or 2, comprising a third bevel gear provided and a fourth bevel gear meshed with the third bevel gear and provided on the rear wheel shaft. .   The rear-wheel drive four-wheel bicycle according to any one of claims 1 to 3, wherein the driving means includes a one-way clutch that allows reverse rotation of the pedal.   The rear wheel drive according to any one of claims 1 to 4, wherein the rear wheel steering shaft portion has a caster angle of 3 to 20 degrees with respect to a vertical line, and a lower end thereof is inclined forward. Four-wheel bicycle.

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