JPH09109603A - Caster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a caster by which traveling performance is improved and traveling sound and vibrational sound are decreased, and a caster provided with a stopper for reliably stopping the rotation of a wheel. SOLUTION: Two axles 13, 14 are respectively and projectingly provided on both surfaces of a wheel supporting body 11 in the tangential direction in relation to the turning locus in the eccentric positions respectively separated from a turning axle 27, and wheels 31a, 31b having the same diameter are supported to the two axles 13, 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applicable to various types of equipment such as dairy equipment, fisheries equipment, commercial kitchen equipment / laboratory trolley, medical equipment, etc. It becomes a target object and is a caster for traveling while being attached to this traveling target object, or a carrier such as a trolley for carrying various objects by the traveling target object, various office furniture such as chairs, and the like. The present invention relates to a caster that is a traveling target object or is attached via these legs (leg blades).

[0002]

2. Description of the Related Art In a conventional caster, as shown in FIG. 9, for example, a thrust bearing type swivel bearing 62 is provided at the lower end of a swivel shaft 61 mounted on the bottom surface of an object to be run such as a trolley so as to have a downward U-shaped cross section. By supporting the wheel support 63 made of a plate-shaped plate piece, the wheel support 63 is provided so as to be freely rotatable, and the wheel support pieces 67a and 67b are two pieces having a U-shaped cross section. In between the wheel 65 and the axle 6
Bearing with 4. The axis of the axle 64 is the wheel support 63.
Is provided at a position distant from the extension line of the turning axis, that is, at a position separated from the turning axis by a predetermined distance in a direction orthogonal to the extension line of the turning axis of the wheel support 63. Therefore, 4
When the casters 60 are mounted on a dolly and run, the axle 64 moves to a position behind the turning axis of the wheel support 63 in the direction of travel of the dolly.

Further, the wheel support 63 is formed by bending a metal plate such as a steel plate, and the wheel support pieces 67a and 67b facing each other and having a U-shaped cross section have elasticity with each other.
In addition, one of the wheel supporting pieces 67a and 67b of the wheel supporting body 63, which is one of the wheel supporting pieces 67a, is formed by bending the stepped portion 6 into a stepped shape in which the step gradually widens toward the lower end of the portion 67a.
8, the outer surface of one of the stoppers 66 having an L-shaped cross section is brought into contact with the outer surface of the wheel support piece 67a provided with the stepped portion 68, and the stopper 66 is rotatably provided at one end of the axle 64. There is.

Therefore, by rotating the stopper 66 in the clockwise direction on the paper surface of FIG. 9, the stopper 66 causes the stepped portion 68 of the wheel supporting piece 67a to move to the wheel supporting pieces 67a, 67.
It presses against the urging forces of the directions b that repel each other. As a result, the inner surfaces of the wheel support pieces 67a, 67b contact the side surfaces of the wheel 65, and the rotation of the wheel 65 is stopped by the frictional force between the inner surfaces of the wheel support pieces 67a, 67b and the side surface of the wheel 65.
On the other hand, by rotating the stopper 66 in the counterclockwise direction on the paper surface of FIG. 9, the wheel support piece 67 is passed through the stepped portion 68.
Since the force pressing the inner surfaces of the a and 67b toward the side surface of the wheel 65 is released, the inner surfaces of the wheel support pieces 67a and 67b are separated from the side surface of the wheel 65 by the urging force of the wheel supporting pieces 67a and 67b to return. The wheels 65 separate from each other, and the wheels 65 can rotate freely.

[0005]

In the conventional caster, it is not possible to smoothly overcome the seams or cracks of the floor astiles, tiles, bricks, etc., and the wheels 65 follow the recesses of the seams or cracks. The carriage oscillates vertically due to the lowering. Therefore,
There is a problem in that a loud vibration noise and a running noise are generated during running, which causes running resistance.

Further, in the conventional caster, the axis of the axle 64 is provided at a position separated from the turning axis by a predetermined distance in the direction orthogonal to the extension line of the turning axis of the wheel support 63, so that the path of the truck is advanced. This is intended to make it easier for the casters to turn and make it easier for the dolly to travel when the vehicle is turned or when the trolley is moved backwards.However, the problem is that the casters do not turn smoothly in practice. there were. For example, the wheels 65 of the caster may reverse when the caster does not immediately turn when the cart is moved backward. However, in this state, the caster 60 does not travel or move indefinitely, and the caster 60 gradually turns when the traveling direction of the carriage slightly changes. In the process of turning the caster 60, the rotation direction of the wheels 65 of the caster is orthogonal to the traveling direction of the dolly. At this point, the dolly suddenly resists and the dolly does not run smoothly. , Sometimes slowed down or even stopped.

If the wheel 65 is made of an elastic material such as rubber, it has some cushioning properties, but it does not have enough cushioning properties to absorb the unevenness of the floor surface. Further, there is a problem that wheels 65 of one or two casters of the four casters 60 are separated from the floor surface and rattling noises and running noises are generated, which causes running resistance.

Further, since the conventional stopper mechanism of the caster 60 has a small force for pressing the wheel support pieces 67a, 67b against the wheels 65 or a frictional force, when the truck is stopped on a steep slope or when a large force acts on the truck. However, there is a problem that the wheels cannot be reliably stopped in the rotation state.

The present invention was developed to solve the above-mentioned problems, and reduces running resistance to improve running performance.
Further, it is an object of the present invention to provide a caster with reduced running noise and vibration noise during traveling, and also to provide a caster with a stopper that surely stops the rotation of the wheels.

[0010]

In order to achieve the above object, the caster 10 of the present invention comprises a wheel support mounted on a traveling object so as to be rotatable on a plane, and a wheel support swinging on the wheel support. In a caster provided with wheels that rotate in a direction orthogonal to the direction and in the vertical direction, two wheels 31a and 31b having the same diameter on the wheel support 11 are orthogonal to the turning direction of the wheel support 11, respectively. The two wheels 3 while supporting the rotary shafts substantially parallel to each other in the direction.
The rotating shafts 1a and 31b are the turning axis 27 of the wheel support 11.
It is provided at an eccentric position with respect to the turning axis 27 on the same plane orthogonal to the.

The caster 10 according to the present invention further comprises:
Two axles 13 and 14 are respectively attached to a wheel support 11 which is mounted on a traveling target object so as to be capable of turning, and the turning axis 27 is provided on the same plane orthogonal to the turning axis 27 of the wheel support 11.
With respect to the eccentric position, the wheels 31a, which are provided tangentially to the turning locus of the position, that is, parallel and opposite to each other, and have the same diameter on the two axles 13 and 14, respectively. 31b is supported.

In another caster 10 of the present invention, a wheel support 11 which is rotatably mounted on an object to be traveled has a substantially flat plate shape having a turning axis 27 at one side edge.
Two axles 13 and 14 are provided on both sides of 1 on the same plane orthogonal to the turning axis 27 of the wheel support 11 at an eccentric position with respect to the turning axis 27 with respect to the turning locus of the position. Wheels 31a, protruding in the tangential direction, that is, parallel to each other, and having the same diameter on the two axles 13, 14 respectively.
31b is supported.

The wheel support 11 has a slewing bearing 12 attached thereto.
Can be integrally provided, and the wheel support 11 can be freely pivoted by bearing the pivot shaft 41 mounted on the traveling target object by the pivot bearing 12.

Further, a slewing bearing 12 having a cylindrical shape having an upper surface opening 26 is integrally provided at one side edge of the wheel support 11 having a substantially flat plate shape, and the slewing shaft 4 is provided in the slewing bearing 12 through the opening 26.
Alternatively, the wheel support 11 can be pivotably provided by inserting 1 for bearing and contacting the lower end surface of the revolving shaft 41 with the bottom surface of the revolving bearing 12 via the cushioning material 44 and the sphere 48.

The cushioning material 44 may be an elastic body made of resin or resin.

Further, an engaging projection 28 having such a height that the swivel shaft 41 can be inserted is provided on the inner peripheral surface of the swivel bearing 12, and a groove portion 42 engaging with the engaging projection 28 is provided with an outer peripheral surface of the swivel shaft 41. Can also be provided.

Further, a water drain hole 25 may be provided on the bottom surface of the slewing bearing 12.

Further, the outer peripheral surface 3 of the wheels 31a, 31b
4 includes an angle of inclination with respect to the rotational axes of the wheels 31a and 31b, and the outer peripheral surface 34 or the wheel frame 36 of the wheels 31a and 31b includes an elastic member.

Further, a wheel 31 is attached to each of the two axles 13 and 14 of the wheel support 11 via a wheel bearing 33.
a, 31b are supported, and the outer peripheral surface 34 of the wheels 31a, 31b
The outermost position of the wheel bearing 33 is located on the center line of the width of the wheel bearing 33.

Further, wheel gears 32a and 32b, which are concentric with the wheel shaft center, are integrally provided on the inner surfaces of the two wheels 31a and 31b which face each other, and the wheel gears 32 are respectively provided.
A stopper 51 having two engaging portions that engage with each other between the teeth of a and 32b is axially attached to the wheel support 11, and the two engaging portions 54a and 54b of the stopper 51 are attached to the two wheel gear 32a. , 32b between the teeth can be engaged and disengaged.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION A caster 10 of the present invention is mounted on a traveling target object such as a carrier such as a trolley or various equipment, and is mounted on a wheel support 11 which is rotatably mounted on the traveling target object. The right wheel 31a and the left wheel 31b, which have the same diameter as each other, are rotationally supported substantially parallel to each other in a direction orthogonal to the turning direction of the wheel support 11. The two right wheels 31a and the left wheels 31b are provided at eccentric positions where their respective rotation axes form different distances from the turning axis 27 on the same plane orthogonal to the turning axis 27 of the wheel support 11. For example, the rotation axis of the right wheel 31a is provided at a position forming a distance L from the turning axis 27, while the left wheel 3a
If the rotation axis of 1b is eccentrically provided at a position forming a distance M from the turning axis 27, and the distance M is longer than the distance L, the grounding point of the right wheel 31a is on the extension line of the turning axis 27 and the floor surface. Is located at a distance L from the intersection C to the rear in the traveling direction of the caster 10, while the ground contact point of the left wheel 31b is located at a distance M from the intersection C to the rear in the traveling direction of the caster 10. Therefore, the ground contact point of the left wheel 31b is the right wheel 31
From the grounding point of a, the caster 10 is in the backward direction (M-
L) (Fig. 2).

Therefore, when the grounding point of one wheel rides on a seam or a crack on the floor surface, the other wheel is grounded on the floor surface, so that one wheel runs smoothly without falling on the seam. Quiet running is obtained with almost no vibration or running noise.

The longer the distance from the intersection C to the ground contact point of the wheel (hereinafter referred to as "turning arm" in the present specification), the force for turning the wheel around the turning axis 27 (hereinafter referred to as "the turning arm" in the present specification). The "turning force") may be small, and the turning resistance of the wheel applied to the ground contact point of the wheel is small.

The entire turning arm of the caster 10 has an intersection C
Can be assumed to be half the sum (L + M) of the distance L from the right wheel 31a to the ground contact point and the distance M from the intersection C to the ground contact point of the left wheel 31b. Therefore, caster 1
The turning arm of 0 is (ML) / from the turning arm L of the right wheel 31a.
Since the turning force of the wheel may be smaller because it becomes longer by two, the vehicle turns more smoothly.

Further, the turning force of the right wheel 31a and the left wheel 31b are different depending on the turning arms of the right wheel 31a and the left wheel 31b.
The turning force is different. In the above example, the turning force of the left wheel 31b may be smaller than the turning force of the right wheel 31a. Moreover, the ground contact points of the right wheel 31a and the left wheel 31b are the turning axis 27.
Since the trucks are located on the left and right with respect to the extension line at the rear of the traveling direction, each wheel has a certain angle on the plane with respect to the intersection point C from the ground contact point when the truck moves backward on a straight line with respect to the forward direction. Therefore, theoretically, the turning arms have M> L, and therefore the turning resistance of the left wheel 31b is greater than that of the right wheel 31a due to the lever principle. Caster 1 because it gets smaller
When a reverse force is applied to 0, the vehicle immediately turns to the side of the left wheel 31b.

The wheel support 11 has a second axle 1
Reference numerals 3 and 14 respectively denote the turning axis 2 of the wheel support 11.
By projecting eccentric positions at different distances from the turning axis 27 on the same plane orthogonal to 7, tangentially to the turning locus of the position, that is, in parallel and in opposite directions, Right wheel 3 supported on the axle 13
1a and the left wheel 31b supported on the axle 14 are rotationally supported parallel to each other in a direction orthogonal to the turning direction of the wheel support 11. For example, the wheel support 11 has a substantially flat plate shape having a turning axis 27 at one side edge, and the wheel support 11 is
By arranging the two axles 13 and 14 on both sides of the wheel so as to project at the above-mentioned positions, respectively, the right wheel 31a and the left wheel 31b supported by the two axles 13 and 14 are in a direction orthogonal to the turning direction of the wheel support 11. The rotating shafts are supported parallel to each other.

Further, a slewing bearing 12 having a cylindrical shape with an upper surface opening 26 is integrally provided at one side edge of the wheel support 11 having a substantially flat plate shape, and the slewing shaft 4 is provided in the slewing bearing 12 through the opening 26.
By inserting 1 and bearing it, the swivel shaft 41 is supported by the long swivel bearing 12, so that the load applied to the swivel shaft 41 is dispersed and the surface pressure applied to the inner peripheral surface of the swivel bearing 12 is reduced. The resistance of the wheel support 11 when turning becomes small and the wheel support 11 turns smoothly. Further, because of the structure of the slewing bearing 12 described above, the slewing bearing 12 having the same length as the height of the wheel can be provided within the range of the height of the wheel. The height to be attached to the target object is kept low.

The lower end surface of the swivel shaft 41 is attached to the swivel bearing 12
Since the contact area between the swivel shaft 41 and the spherical body 48 is small by contacting the bottom surface of the swivel member with the cushioning member 44 such as an elastic body made of a resin or the like and the spherical body 48, the swivel resistance of the swivel shaft 41 becomes small and smooth. Turn to.

Further, since the cushioning material 44 absorbs the load applied to the slewing bearing 41 and generates an urging force that constantly pushes the wheel downward, the load applied to the four casters mounted on the traveling object varies. Even if the floor surface is uneven, the four casters always contact the floor surface.

Further, an engaging projection 28 having a height that allows the swivel shaft 41 to be inserted is provided on the inner peripheral surface of the swivel bearing 12, and a groove portion 42 engaging with the engaging projection 28 is provided on the outer peripheral surface of the swivel shaft 41. Since the swivel shaft 41 is not easily disengaged from the swivel bearing 12, the swivel shaft 41, the sphere 48, the cushioning member 44 and the like can be easily replaced because they can be easily attached and detached by human power.

Further, by providing the drain hole 25 on the bottom surface of the slewing bearing 12, corrosion can be prevented even when the caster is washed with water.

Further, since the outer peripheral surfaces 34 of the wheels 31a and 31b form an inclination angle with respect to the rotational axes of the wheels 31a and 31b, the outermost peripheral positions of the outer peripheral surfaces 34 of the wheels 31a and 31b are partially located on the floor surface. Since the wheels are grounded, the contact surfaces of the wheels 31a and 31b are reduced. Therefore, the resistance of the wheels 31a and 31b when traveling and the resistance of the wheels 31a and 31b when turning are reduced, so that the vehicle can travel smoothly.

Further, when a load is applied to the wheels 31a and 31b, the outer peripheral surfaces 34 of the wheels 31a and 31b or the wheel frame 36 are flexible because they are elastic, and the outer peripheral surface 34 or the wheel frame 36 is bent depending on the magnitude of the load. Since the deflection amount of 36 is different, the ground contact surfaces of the wheels 31a and 31b increase or decrease. Therefore, an appropriate ground contact surface is generated according to the magnitude of the load applied to the wheels 31a and 31b, which causes a synergistic effect between the running performance of the wheels 31a and 31b and the load performance to smoothly travel.

Further, a wheel 31 is attached to each of the two axles 13 and 14 of the wheel support 11 via a wheel bearing 33.
a, 31b are supported, and the outer peripheral surface 34 of the wheels 31a, 31b
Since the outermost position of the wheel bearing 33 is located on the center line of the width of the wheel bearing 33, only the vertical load is applied to the wheel bearing 33. Therefore, the rotation of the wheel bearing 33 is in a smooth state, so that the traveling performance of the wheels 31a and 31b is not unreasonable and the traveling noise is reduced.

Further, wheel gears 32a and 32b, which are concentric with the wheel shaft center, are integrally provided on the inner surfaces of the two wheels 31a and 31b that face each other, and the wheel gears 32 are
A stopper 51 having two engaging portions engaging between the teeth of a and 32b is axially attached to the wheel support 11, and the stopper 5
The two locking portions 54a and 54b of the first wheel gear 32
Since the teeth a and 32b are provided so as to be engageable and disengageable, even if a large force is applied to the traveling target object or the traveling target object is stopped on a steep slope, the two wheels can be operated by operating the stopper 51. The rotation of 31a and 31b surely stops.

In the above casters, the wheel body such as the inner ring portion 35, the wheel frame 36, and the outer ring portion 37 of the wheel and the wheel support 11 are made of glass fiber, and the tire portion 38 of the wheel is made of urethane resin. As a result, the running noise of the casters is significantly reduced.

Further, since the wheel body and the wheel support 11 are made of a resin material and the turning shaft 41 and the spherical body are made of stainless steel, the corrosion resistance of the caster can be increased.

Further, since the caster is entirely formed into a smooth surface, the drainage hole 25 is provided on the bottom surface of the slewing bearing 12, and the caster is made to have an open structure, corrosion resistance is increased. It can be easily washed with water, for example by high pressure spray.

[0039]

Embodiments of the caster of the present invention will be described below with reference to the drawings. In the present embodiment, a trolley for carrying various items is a traveling target object to which the caster 10 of the present embodiment is attached.

In FIG. 2, reference numeral 41 denotes a swivel axis having a diameter of 12
mm, a length of about 110 mm, and provided with a screw portion 43 at one end thereof for fixing to a trolley, which is an object to be traveled, and at the position of about 13 mm from the other end on the outer peripheral surface on the other end side. Approximately 1 mm with a width of approximately 10 mm in the axial direction of
The groove portion 42 having a depth of about one degree is provided so as to make one round. The swivel shaft 41 can be, for example, provided with a female screw on a carriage, and the screw portion 43 of the swivel shaft 41 can be screwed and fixed to the female screw, or an insertion hole can be provided on the bogie, and the screw can be inserted into the insertion hole. Part 4
3 can be inserted, and a nut can be screwed to the tip of the screw portion 43 and tightened to be fixed to the carriage.

Reference numeral 11 denotes a wheel support, which comprises a slewing bearing 12 having a cylindrical shape having an opening 26 at one end and closed at the other end, and a substantially flat plate-shaped support frame 15 having a substantially circular plane. One side edge of the support frame 15 is integrally fixed to the side wall surface of the slewing bearing 12 substantially parallel to the axial direction of the slewing bearing 12. In the present embodiment, the slewing bearing 12 has an inner peripheral surface capable of bearing the slewing shaft 41 inserted through the opening 26 and has an inner diameter of 12 mm and a depth of about 90 mm. In addition, the closed wall surface at one end of the slewing bearing 12 has a diameter of 4 mm.
A drainage hole 25 of a certain degree is formed. Slewing bearing 1
2, three engaging protrusions 28 having a minute height on the inner peripheral surface,
It is projected at equal intervals of 120 degrees. The engaging projection 28 is a cylindrical projection having a diameter of about 3 mm, and the height up to the tip thereof is such that pressure is applied to the swivel shaft 12 by hand when the swivel shaft 41 is inserted into the swivel bearing 12. 41 is formed with a minute size that allows it to pass over the three engagement protrusions 28 and pass therethrough.

The details of the wheel support 11 are shown in FIGS. 5, 6 and 7. In FIG. 6, the support frame 15 is a side edge opposite to the side edge integrally attached to the slewing bearing 12. Is partially cut away, and reinforcing ribs are provided on the other two side edges excluding this notch so as to form a T-shaped cross section. That is, the upper rib 16 is provided on one side edge of the slewing bearing 12 on the opening 26 side, and the lower rib 17 is provided on the other side edge.

A right axle 13 is provided so as to project on one surface of the support frame 15, that is, on the surface in the right direction on the paper of FIG. 5, and on the other side of the support frame 15, that is, on the left of the paper of FIG. A left axle 14 is provided so as to project on the surface in the direction, and the axis of the right axle 13 and the axis of the left axle 14 are slewing bearings 12.
On the same plane orthogonal to the turning axis 27 of the right axle 1
3 is located at a distance of 40 mm from the turning axis 27, and the axis of the left axle 14 is located at a distance of 53 mm from the turning axis 27 (FIG. 6). Therefore, the axis of the right axle 13 and the left axle 14
The distance from the axis of is 13 mm.

In each of the right axle 13 and the left axle 14, the wheel support 11 has the slewing axis 2 of the slewing bearing 12.
The tangential direction, that is, the protrusion that is parallel to the turning locus at the position of each axle when the vehicle turns around 7, is such that the rotation directions of the right wheel 31a and the left wheel 31b supported by each axle are wheel support. It is desirable in that it is orthogonal to the turning direction of the body 11.

The support frame 15 is the right axle 1.
Three rows of endless annular reinforcing annular ribs 19a and 19b are provided in a protruding manner on the surfaces of the outer peripheral surface of the vehicle 3 and the left axle 14, respectively. The annular ribs 19a and 19b and the slewing bearing 1 are provided.
Between the two, as shown in FIG. 7, the supporting body frame 15 sequentially forms a circular arc having a cross-section cutout from one side surface of the supporting body frame 15 to the other side surface to form a corrugated plate-shaped reinforcing portion 18 (18, 18). And the strength is increasing.

Further, the support frame 15 is provided with an edge portion 21 having a triangular cross section at one end of the above-mentioned notch, and further, an axial hole 22 is provided in the vicinity of above the edge portion 21 on the plane of FIG. There is. In addition, hemispherical projections 23, 23 having an arcuate cross section are provided on both sides of the support frame 15 in the vicinity of the upper rib 16 diagonally above the shaft hole 22 in the plane of FIG.

In FIG. 1, 31a is a right wheel, and 31b is a right wheel.
Is a left wheel, and the left and right wheels 31b and 31a have the same shape, size, and structure. By the way, the diameter of both left and right wheels 31b, 31a is 125 mm.
And the width is 14 mm. The right wheel 31a is connected to the wheel support 11
Of the left wheel 3 by bearings on the right axle 13 of the vehicle through wheel bearings 33.
FIG. 3 shows an assembled state in which 1b is supported on the left axle 14 of the wheel support 11 via a wheel bearing 33. In this embodiment, the wheel bearing 33 has a sealed structure so that water does not enter the wheel bearing 33 even if the caster is submerged in water or washed with water.

The right wheel 31a will be described below with reference to the drawings. The left wheel 31b has the same structure as the right wheel 31a. 3 and 4, the right wheel 31a is the inner ring portion 3
5 is provided with a bearing case for mounting the wheel bearing 33,
The outer ring portion 37 is formed in an endless annular shape having a width of 14 mm, and the wheel itself is provided with elasticity by integrally connecting the outer ring portion 37 with the wheel frame 36 formed around the inner ring portion 35 with a thickness of about 4 mm. There is. In the present embodiment, the bearing case has a labyrinth structure, and the labyrinth structure has a sealed structure, so that the wheel bearing 33 is protected from the entry of high-pressure water, dust, and other impurities.

Further, an endless annular tire portion 38 made of an elastic material, urethane rubber in this embodiment, is attached to the outer periphery of the outer ring portion 37, and the outer peripheral surface 34 of the tire portion 38 is the right wheel 31a. It forms an inclination angle with respect to the axis of rotation, and the outermost peripheral position of the outer peripheral surface 34 is located on the extension line of the center line in the width direction of the wheel bearing 33 mounted on the bearing case. In this embodiment, the bearing case of the inner ring portion 35 has a shape protruding from the inner surface of the wheel frame 36, and is used to fix the inner ring of the wheel bearing 33 mounted in the bearing case to the right axle 13 of the wheel support 11. Working holes are provided in the inner ring portion 35. Further, a right wheel gear 32a is formed on the inner wall surface of the wheel frame 36 and located on the outer periphery of the bearing case.

The above right wheel 31a is supported on the right axle 13 of the wheel support 11 via the wheel bearing 33, and the flat washer 45 is screwed to the end face of the right axle 13 from the working hole of the inner ring portion 35 with the drill screw 46. As a result, the inner ring of the wheel bearing 33 is connected to the support frame 1 of the wheel support 11 on the surface of the plain washer 45.
The surface of 5 is pressed and fixed. Further, the inner ring portion 35
Attach the wheel cap 47 to the work hole of. on the other hand,
A left wheel 31b having the same shape as the right wheel 31a is mounted on the left axle 14 of the wheel support 11 via a wheel bearing 33 and a right wheel 31b.
Mount and bearing as in a. Therefore, the right wheel 3
Each of the left wheel 1a and the left wheel 31b is rotatably supported in a direction orthogonal to a direction in which the wheel support 11 turns on the turning axis 27 of the turning bearing 12.

As described above, the axis of the right axle 13 and the axis of the left axle 14 are on the same plane orthogonal to the axis 27 of the slewing bearing 12, and the axis of the right axle 13 is the axis of slewing. Two
Since it is located at a distance of 7 to 40 mm, and the axis of the left axle 14 is located at a distance of 53 mm from the turning axis 27, the grounding point of the right wheel 31a supported on the right axle 13 is the turning axis 2
It is located at a distance of 40 mm behind the intersection C of the extension line of 7 and the floor surface in the traveling direction of the caster 10, while the ground contact point of the left wheel 31b supported by the left axle 14 is the turning axis 27.
It is located at a distance of 53 mm behind the intersection point C of the extension line and the floor surface in the traveling direction of the caster 10. Therefore, the grounding point of the left wheel 31b is located at a distance of 13 mm behind the grounding point of the right wheel 31a in the traveling direction of the caster 10 (FIG. 2).

In FIG. 2, reference numeral 44 designates a cushioning material, which in this embodiment is a cylindrical urethane rubber having a diameter of 12 mm and a height of about 10 mm, and has the same shape as the spherical surface of a spherical body 48 described later on both end faces thereof. It forms a recess. The cushioning material 44 may be made of elastic material or other elastic resin. The cushioning material 44 is inserted into the slewing bearing 12 of the wheel support 11 through the opening 26 and then the sphere 48. The end surface of the cushioning member 44 is brought into contact with the bottom surface of the slewing bearing 12,
The spherical body 48 is brought into contact with the surface of the recess of the cushioning material 44. The spherical body 48 is made of a hard material such as steel, and is a steel ball having a diameter of 10 mm in this embodiment. Furthermore, the slewing bearing 1
The swivel shaft 41 is inserted through the second opening 26, and the tip of the swivel shaft 41 is brought into contact with the apex of the spherical body 48. Three engaging projections 28, 28, 28 provided on the inner peripheral surface of the slewing bearing 12 engage with the groove portion 42 of the slewing shaft 41 at a position where the tip of the slewing shaft 41 abuts on the apex of the sphere 48. Moreover, it is located near the lower wall surface of the groove 42. Since the groove portion 42 has a width of about 10 mm in the axial direction of the swivel shaft 41, when a load is applied to the swivel shaft 41 and the tip of the swivel shaft 41 presses the cushioning member 44 via the spherical body 48, the swivel shaft 41 moves downward. As a result, depending on the magnitude of the load applied to the swivel shaft 41, the engaging protrusions 28, 2
Apparently, 8 and 28 move up and down in the groove 42.

As described above, since the engaging projections 28, 28, 28 on the inner peripheral surface of the slewing bearing 12 and the groove portion 42 of the slewing shaft 41 are engaged with each other, the slewing shaft 41 is easily separated from the slewing bearing 12. However, since the engaging projection 28 is a minute projection, the swivel shaft 41 can be easily attached to and detached from the swivel bearing 12 with a certain amount of manual force. Therefore, the swivel shaft 41, the sphere 48, and the cushioning member 44 can be easily replaced.

[Structure of Stopper 51] In FIG. 2, 5
Reference numeral 1 denotes a stopper, the detailed structure of which is shown in FIGS.
(B) and FIG. 8 (C) are shown. In FIG. 8 (A), a plate-shaped right arm 53a and a left arm 53b are integrally formed on the concave surface of the gently curved plate-shaped operation portion 52 so as to have a U-shaped cross section. The right locking portion 54a is provided on the side wall surface at the tip of the 53a, while the left locking portion 54b is provided on the side wall surface at the tip of the left arm 53b. The inner surfaces of the right arm 53a and the left arm 53b that face each other are reinforced with a large plate thickness.
Rotating shafts 55a and 55b are provided on the inner surfaces of 3a and the left arm 53b so as to face each other.
A gap 56 is formed between the front end surface and b.

The rotating shafts 55a and 55b are formed to have a diameter that fits into the shaft hole 22 provided in the support frame 15 of the wheel support 11 described above. The distance from the rotary shaft 55a to the right locking portion 54a and the distance from the rotary shaft 55b to the left locking portion 54b are different, and the rotary shafts 55a and 55b are inserted into the shaft hole 22. When the stopper 51 is rotated, the right locking portion 54a is provided at a position that engages between the teeth of the right wheel gear 32a of the right wheel 31a, while the left locking portion 54b is positioned at the left wheel gear 32b of the left wheel 31b. It is provided at a position to be engaged between the teeth of the. Further, a plate-shaped right engaging rod 57a is projectingly provided on a side edge of the right arm 53a, while a left engaging rod 57b having the same shape as the right engaging rod 57a is provided on a side edge of the left arm 53b.
Is provided so as to face the right engaging rod 57a.

The left and right engaging rods 57b and 57a are
Rotate the stopper 51 around the shaft hole 22 to rotate the right locking portion 54.
a is engaged and disengaged between the teeth of the right wheel gear 32a of the right wheel 31a, while the left locking portion 54b is engaged and disengaged between the teeth of the left wheel gear 32b of the left wheel 31b. 57
The tips of b and 57a are formed so as to rotate over the hemispherical projections 23 and 23 formed on both surfaces of the support frame 15 of the wheel support 11.

The rotating shafts 55a, 55 of the stopper 51 described above
Since the right arm 53a and the left arm 53b have elasticity when the b is attached to the shaft hole 22 of the wheel support 11, the support frame 15 is provided in the gap 56 between the tips of the rotating shafts 55a and 55b. Push in the edge part 21 and push the right arm 53
The gap 56 is expanded against the elasticity of a and the left arm 53b, and the rotating shafts 55a and 55b are inserted into the shaft hole 22 of the wheel support 11 (FIG. 2).

[Operation of Caster 10; Without Stopper or When Stopper is Released] The operation of the caster 10 in the case where the above four casters 10 are mounted on the carriage will be described below.

In FIG. 2, the respective ground contact points of the right wheel 31a and the left wheel 31b are located rearward in the traveling direction of the caster 10 from the intersection C of the extension line of the turning axis 27 and the floor surface, and the right wheel 31a and the left wheel 31b. The grounding points of the wheels 31b are not located at the same distance behind the caster 10 in the traveling direction, but the grounding point of one of the right wheel 31a and the left wheel 31b is located behind the grounding point of the other wheel. (In this embodiment, the ground contact point of the left wheel 31b is located behind the ground contact point of the right wheel 31a in the traveling direction of the caster 10)
Therefore, even if there are seams or cracks on the floor such as astiles, tiles, bricks, etc., when one wheel rides on the seam on the floor, the other wheel is grounded on the floor, so one seam One wheel may move forward without falling on the seam, and then the other wheel may fall on the seam when one wheel is on the floor when the other wheel rides on the floor seam. Without running smoothly. As a result, the caster 10 produces quiet running performance with almost no vibration or running noise.

The distance from the intersection C to the ground contact point of the wheel, that is, the longer the turning arm, the smaller the force for turning the wheel around the turning axis 27, that is, the turning force, may be, and the turning of the wheel applied to the grounding point of the wheel may be reduced. The resistance becomes smaller. The total swing arm of the caster 10 can be assumed to be the distance from the intersection C to the center position between the ground contact points of the right wheel 31a and the left wheel 31b. That is, in this embodiment, the entire turning arm of the caster 10 is the turning arm 40 of the right wheel 31a.
mm and a difference of 13 mm from the intersection C to the ground contact points of the right wheel 31a and the left wheel 31b, which is half the length 6.5m.
It can be assumed that the distance is 46.5 mm plus m. Therefore, the swivel arm of the caster 10 has the above-mentioned 6.5.
The turning force of the wheel may be smaller since it is longer by mm. That is, the caster 1 when the trolley changes direction.
0 turns more smoothly.

Since the right wheel 31a and the left wheel 31b have different turning arms, the turning force of the right wheel 31a and the left wheel 31b are different.
The turning force is different. That is, in this embodiment, the right wheel 31a
The turning force of the left wheel 31b may be smaller than the turning force of. Moreover, the ground contact point of the right wheel 31a and the ground contact point of the left wheel 31b are approximately 1 to the left and right of the traveling locus of the turning axis 27, respectively.
It is located at a distance of 3 mm. Therefore, when the bogie reverses, the right wheels 31a and the left wheels 31b turn in opposite directions, but the turning resistance of the left wheel 31b is smaller than the turning resistance of the right wheel 31a. When a reverse force is applied to 10, the vehicle immediately turns to the side of the left wheel 31b. In order to explain in more detail, considering the case where the right wheel 31a and the left wheel 31b have the same turning arm, the directions in which the right wheel 31a and the left wheel 31b try to turn when the bogie moves backward are opposite to each other. However, even if a reverse force is applied, since the turning force and turning resistance of the right wheel 31a and the left wheel 31b are the same, they will not move in a balanced manner and will go backwards as they are. I can't turn to.

In the bearing structure in the slewing bearing 12, since the contact area between the lower end surface of the slewing shaft 41 and the apex of the sphere 48 is small, the resistance when the slewing shaft 41 rotates on the sphere 48 becomes small. 12 smoothly rotates on the outer peripheral surface of the swivel shaft 41. That is, the wheel support 11 smoothly turns around the turning axis 41.

Further, since the slewing shaft 41 is supported by the slewing bearing 12 which is a long sliding bearing, the load applied to the slewing shaft 41 is reduced because the surface pressure applied to the inner peripheral surface of the slewing bearing 12 is dispersed. Therefore, the resistance of the wheel support 11 at the time of turning becomes small, and the wheel support 11 smoothly turns around the turning shaft 41.

Further, although the slewing bearing 12 is long, due to the structure of the slewing bearing 12 and the left and right axles 14 and 13 provided on the wheel support 11, the size of the wheels is 125 mm in diameter and the left and right wheels 31 b and 31 a. From the ground point to the screw part 4 of the swivel shaft 41
The height to the base of 3 is 143 mm, and the difference is 18 mm.
I keep it low.

Further, the load applied to the sphere 48 is reduced by the cushioning material 44.
The load applied to the swivel shaft 41 is received by the swivel shaft 4.
The cushioning material 44 is pressed from the tip of 1 via the sphere 48, and the cushioning material 44 absorbs the load. Therefore, even if the loads applied to the four casters 10 are different, the urging force that absorbs the load and pushes the swivel shaft 41 upward by the buffer material 44 in the swivel bearing 12 of each caster 10 (that is, the swivel bearing 12 is moved downward). (Urging force to push down to) also occurs, so 4
The right and left wheels 31a and 31b of each caster 10 are always grounded on the floor. As a result, the load applied to the dolly is distributed to the casters 10, so that the wheels of the casters 10 smoothly turn and rotate, so that the running noise decreases and the running resistance decreases, so that the running direction and speed of the dolly are reduced. It is easy to control the increase and decrease. Furthermore, since the right and left wheels 31a and 31b of the four casters 10 are always in contact with the floor surface, smooth running is possible even on an uneven floor surface, so that adverse effects on vibration on the transported object on the carriage are reduced. I will let you.

Further, the outer peripheral surfaces 3 of the left and right wheels 31b, 31a
Since 4 forms an angle of inclination with respect to the rotational axes of the left and right wheels 31b and 31a, the outermost peripheral positions of the outer peripheral surfaces 34 of the left and right wheels 31b and 31a partially contact the floor surface. Therefore, the ground contact surfaces of the left and right wheels 31b and 31a become smaller, so that the resistance of the left and right wheels 31b and 31a during running and the left and right wheels 31a and 31b.
The resistance at the time of turning of b and 31a becomes small.

Further, the outermost tire portion 38 of the left and right wheels 31b, 31a has elasticity, and the wheel frame 36
Has elasticity, the outer peripheral surface 34 of the tire portion 38 of the left and right wheels 31b and 31a or the wheel frame 36 will bend when a load is applied to the left and right wheels 31b and 31a. Therefore, the deflection amount of the outer peripheral surface 34 of the left and right wheels 31b and 31a or the wheel frame 36 changes according to the magnitude of the load applied to the left and right wheels 31b and 31a, and the ground contact surface of the left and right wheels 31b and 31a changes according to the deflection amount. Will increase or decrease. That is, when the load applied to the left and right wheels 31b and 31a is large, the outer peripheral surface 34 of the tire portion 38 and the wheel frame 36.
Since the deflection amount of the left and right wheels 31b and 31a increases, the load bearing performance of the left and right wheels 31b and 31a improves. On the other hand, when the load applied to the left and right wheels 31b and 31a is small, the amount of deflection of the outer peripheral surface 34 of the tire portion 38 and the wheel frame 36 decreases, so the left and right wheels 31
The left and right wheels 31b and 31a are
Driving performance is improved. That is, the left and right wheels 31b, 3
Left and right wheels 31b, 3 depending on the magnitude of the load applied to 1a
The left and right wheels 3 will produce a suitable ground contact surface for 1a.
The left and right wheels 31b and 31a travel smoothly by causing a synergistic effect of the running performance and load performance of the 1b and 31a.

Further, the outer peripheral surfaces 3 of the left and right wheels 31b, 31a
Since the outermost peripheral position of 4 is the ground contact point and the outermost peripheral position of the outer peripheral surface 34, that is, the ground contact point of the left and right wheels 31b and 31a is located on the extension line of the center line of the width of the wheel bearing 33, it is perpendicular to the wheel bearing 33. Only the load is applied. As a result, the rotation of the wheel bearing 33 becomes smooth, so that the left and right wheels 31
The running characteristics of b and 31a are reasonable and the running noise is reduced.

By the way, the caster 10 of this embodiment is
The running resistance at the start of running is reduced by about 50% compared to the running resistance of conventional casters, and the running resistance after running is reduced by about 30% as compared to the running resistance of conventional casters. There is. For example, the noise level when 13 casters 10 of the present invention were run simultaneously was about the same as the noise level of one conventional caster.

[Operation of Stopper 51] As shown by the solid line in FIG. 2, the stopper 51 is rotated counterclockwise in FIG. 2 so that the tip ends of the left and right engaging rods 57b and 57a are left and right engaging rods. 57b, 57a against the elasticity between the hemispherical projections 23, 23 to move below the hemispherical projections 23, 23 and to the right locking portion 54a at each tip of the right arm 53a and the left arm 53b. And the left locking portion 54b is the right wheel 3.
1a and the left wheel 31b of the right wheel gear 32a and the left wheel gear 32b are disengaged from between the teeth, and the right wheel 31a and the left wheel 31b become rotatable. On the other hand, as shown by the chain double-dashed line in FIG. 2, by rotating the stopper 51 clockwise in the plane of FIG. 2, the tip ends of the left and right engaging rods 57b, 57a pass over the hemispherical projections 23, 23. Hemispherical protrusion 23,
23 and a right locking portion 54a and a left locking portion 54b at the tips of the right arm 53a and the left arm 53b.
Is the right wheel gear 32a of the right wheel 31a and the left wheel 31b
And the left wheel gear 32b is engaged between the teeth to stop the rotation of the right wheel 31a and the left wheel 31b.

The stopper 51 rotates the operating portion 52 with a human foot or hand, and each time the stopper 51 is rotated, the tip ends of the left and right engaging rods 57b and 57a are hemispherical projections 2.
Since the hemispherical projections 23, 23 are moved over and move over the hemispherical projections 23, 23, unless the force for rotating the stopper 51 is applied, that is, the right locking portion 54a.
The left engagement portion 54b is maintained in the engaged or disengaged state between the teeth of the right wheel gear 32a and the left wheel gear 32b.

[0072]

Since the present invention is configured as described above, it has the following effects.

(1) The two wheel bearings having the same diameter are mounted on the wheel support bodies so as to rotate substantially parallel to each other in the direction orthogonal to the turning direction of the wheel support body, and the rotation shafts of the two wheel support wheels. Is eccentrically provided at positions on the same plane orthogonal to the turning axis of the wheel support body at different distances from the turning axis, so that the grounding point of the two wheels is behind the turning axis in the traveling direction of the caster. It will be in a different position. When one of the wheels touches the seam or crack on the floor surface, the other wheel is grounded on the floor surface. Almost no noise was generated and quiet running performance was obtained.

(2) Since the swivel arms of the two wheels are different, the swivel arm of the caster is longer than the wheel of the shorter swivel arm by half the difference between the swivel arms of the two wheels. It became smaller and turned smoothly.

(3) Since the turning arms of the two wheels are different and the grounding points of the two wheels are located on the left and right with respect to the extension line behind the turning axis in the traveling direction, the turning arm of the longer wheel Since the turning resistance is smaller than that of the wheel with the shorter turning arm, it was possible to provide a caster in which the turning arm immediately turns to the side of the wheel with the longer turning arm when a reverse force is applied to the caster.

(4) Since a slewing bearing having a cylindrical shape having an upper surface opening is integrally provided on one side edge of the substantially flat plate-like shape of the wheel support, and the slewing shaft is inserted into the slewing bearing from the opening and is supported, the bearing is long. Since the surface pressure applied to the inner peripheral surface of the slewing bearing is small, the resistance of the wheel support at the time of slewing can be reduced and the wheel can be smoothly slewed.

(5) With the structure of the slewing bearing, it is possible to provide a slewing bearing having a length substantially equal to the height of the wheel within the range of the height of the wheel. It was possible to reduce the height of attachment to the target object.

(6) Since the lower end surface of the swivel shaft is brought into contact with the bottom surface of the swivel bearing through a cushioning material such as a spring or an elastic body made of resin and a spherical body, the swivel shaft, the spherical body, and the swivel resistance are made small and smooth. I was able to turn.

(7) Since the cushioning material absorbs the load applied to the slewing bearing and generates the urging force that constantly pushes the wheel downward, the four casters mounted on the running object can be grounded on the floor at all times. It was

(8) Since the engaging projection having a height that allows the swivel shaft to be inserted is provided on the inner peripheral surface of the swivel bearing, and the groove portion that engages with the engaging projection is provided on the outer peripheral surface of the swivel shaft, The swivel shaft can be easily attached to and detached from the swivel bearing by the force of
The cushioning material could be easily replaced.

(9) Since the outer peripheral surface of the wheel forms an inclination angle with respect to the rotational axis of the wheel, the outermost peripheral position of the outer peripheral surface of the wheel partially touches the floor surface and the ground contact surface of the wheel decreases. It was possible to provide a caster in which the resistance when the wheels are running and the resistance when the wheels are turning can be reduced and the running is smooth.

(10) Since the outer peripheral surface of the wheel or the wheel frame has elasticity, the amount of deflection of the outer peripheral surface or the wheel frame differs depending on the magnitude of the load applied to the wheel. It was possible to provide a caster that smoothly travels by generating an appropriate ground contact surface according to the magnitude of the load applied to the wheel, and by producing a synergistic effect between the running performance of the wheel and the load performance.

(11) Since the wheels are supported by the two axles of the wheel support through the wheel bearings, respectively, and the outermost peripheral position of the outer peripheral surface of the wheel is located on the center line of the width of the wheel bearing, Since only the vertical load is applied to the bearings, the rotation of the wheel bearings was in a smooth state, the running properties of the wheels were reasonable, and the running noise was reduced.

(12) Wheel gears concentric with the wheel shaft center are integrally provided on the inner surfaces of the two wheels facing each other,
A stopper having two locking portions that engage between the teeth of each wheel gear is axially attached to the wheel support, and the second locking portion of the stopper engages and disengages between the teeth of the two wheel gears. Since it was installed freely, the rotation of the two wheels could be stopped reliably.

[Brief description of the drawings]

FIG. 1 is a front view showing an entire caster according to an embodiment of the present invention, as viewed from the rear in the traveling direction of the caster.

FIG. 2 is a sectional view taken along the line II-II of FIG.

3 is a cross-sectional view taken along the line III-III in FIG.

FIG. 4 is a front view of the right wheel taken along the line IV-IV in FIG.

FIG. 5 is a front view of the wheel support seen from the rear in the traveling direction of the caster of the embodiment of the invention.

6 is a left side view of the wheel support of FIG.

7 is a cross-sectional view taken along the line VI-VI in FIG.

FIG. 8 (A) is a front view of the stopper as seen from the rear in the traveling direction of the caster of the embodiment of the present invention. FIG.
FIG. 8B is a side view of FIG. FIG. 8C shows
It is a top view of the operation part 52 of FIG.8 (B).

FIG. 9 is an overall perspective view of a conventional caster.

[Explanation of symbols]

 10 Casters 11 Wheel Support 12 Slewing Bearing 13 Right Axle 14 Left Axle 15 Support Frame 16 Upper Rib 17 Lower Rib 18 Reinforcement 19 Annular Rib 21 Edge 22 Axis Hole 23 Hemispherical Projection 25 Drain Hole 26 Open 27 Shaft center 28 Engagement protrusion 31a Right wheel 31b Left wheel 32a Right wheel gear 32b Left wheel gear 33 Wheel bearing 34 Outer peripheral surface 35 Inner ring part 36 Wheel frame 37 Outer ring part 38 Tire part 41 Swivel shaft 42 Groove part 43 Screw part 44 Cushioning material 45 Flat washer 46 Drill screw 47 Wheel cap 48 Sphere 51 Stopper 52 Operation part 53a Right arm 53b Left arm 54a Right locking part 54b Left locking part 55a, 55b Rotating shaft 56 Gap 57a, 57b (right / left) engaging rod 60 Caster 61 Slewing shaft 62 Slewing bearing 63 Wheel support 6 Axle 65 wheels 66 stoppers 67a, 67b wheel support piece 68 stepped portion

Claims (11)

[Claims] 1. A wheel support which is mounted on a traveling object so as to be rotatable, and a caster in which a wheel is rotatably supported on the wheel support in a direction orthogonal to a turning direction of the wheel support. Two wheels are provided on the wheel support. The wheels having the same diameter are rotationally supported substantially parallel to each other in the direction orthogonal to the turning direction of the wheel support, and the rotational axes of the two wheels are orthogonal to the turning axis of the wheel support. A caster provided on the same plane at an eccentric position with respect to the turning axis. 2. A wheel support which is mounted on a traveling target object so as to be rotatable, and a caster in which a wheel is rotatably supported by the wheel support in a direction orthogonal to the turning direction of the wheel support. Axles are respectively provided on the same plane orthogonal to the turning axis of the wheel support at an eccentric position with respect to the turning axis in a direction tangential to the turning locus of the position and in directions opposite to each other, Each of the two axles,
A caster characterized by bearing wheels of the same diameter. 3. A wheel support which is rotatably mounted on an object to be traveled, and a caster in which a wheel is rotatably supported on the wheel support in a direction orthogonal to the turning direction of the wheel support, wherein the wheel support is one side. It has a substantially flat plate shape with a turning axis at the edge, and two axles on both sides of the wheel support, respectively,
On the same plane orthogonal to the turning axis of the wheel support, the eccentric position with respect to the turning axis is provided in a tangential direction with respect to the turning locus of the position, and the two axles have the same diameter. A caster characterized by bearing the wheels that it makes. 4. A slewing bearing is integrally provided on the wheel support,
The caster according to claim 1, 2 or 3, wherein a wheel support is rotatably provided by bearing a turning shaft mounted on a traveling target object by the turning bearing. 5. A slewing bearing having a cylindrical upper surface opening is integrally provided at one side edge of the substantially flat plate shape of the wheel support, and a slewing shaft is inserted from the upper surface opening into the slewing bearing for bearing. The caster according to claim 1, 2, 3 or 4, wherein a lower end surface of the swivel shaft is in contact with a bottom surface of the swivel bearing via a cushioning material and a sphere so that the wheel support is swivelably provided. 6. The caster according to claim 5, wherein the cushioning material is a spring or an elastic body made of resin. 7. The slewing bearing according to claim 5, wherein a protrusion having a height capable of inserting the slewing shaft is provided on an inner peripheral surface of the slewing bearing, and a groove portion engaging with the protrusion is provided on an outer peripheral surface of the slewing shaft. caster. 8. The caster according to claim 5, wherein a water drain hole is provided on the bottom surface of the slewing bearing. 9. The wheel according to claim 1, wherein the outer peripheral surface of the wheel forms an inclination angle with respect to the rotation axis of the wheel, and the outer peripheral surface of the wheel or the wheel frame is made of an elastic member. caster. 10. A wheel is borne by a wheel bearing on each of the two axles of the wheel support, and the outermost peripheral position of the outer peripheral surface of the wheel is located on the center line of the width of the wheel bearing. The caster according to any one of ~ 9. 11. A stopper provided with wheel gears concentric with a wheel shaft center integrally on inner surfaces of the two wheels facing each other, and having two locking portions to be engaged between teeth of each wheel gear. The caster according to any one of claims 1 to 10, wherein the caster is axially attached to the wheel support, and the two locking portions of the stopper are provided so as to be freely engageable and disengageable between the teeth of the two wheel gears.