JPH1191303A - Revolving type caster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve directional stability of a revolving type caster and restrain side run-out of a wheel. SOLUTION: This caster consists of a mounting pedestal 14 for fixing it to a frame of a truck, a revolving frame 18 mounted to the mounting pedestal 14 such that it can revolve around a vertical revolving axis X, a bracket 20 dangling from the revolving frame, a rocking arm 30 oscillatably mounted to the bracket 20 through a horizontal fulcrum shaft 01 , an wheel 12 which is rotatably mounted to one end of the rocking arm 30 through a horizontal rotational shaft 02 , and a buffer mechanism 40 which is placed between the other end of the rocking arm 30 and the bracket 20, and energizes one end of the rocking arm 30 downward. The fulcrum shaft 01 is set to be on the same level as the rotational shaft 02 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a caster used by being attached to the bottom of a wheelbarrow or other various luggage carriers, and more particularly, to the direction restorability of a swivel-type caster capable of freely turning in a horizontal plane. Is an improvement.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 7-77842 discloses a swivel type caster having a shock absorbing mechanism. As shown in FIG. 6A, the caster includes a pair of brackets 2 hanging down from both sides of the mounting portion 1, a fixed abutment surface portion 3a extending rearward of the bracket 2, and a midway between the brackets 2. A wheel support arm 4 whose part is pivotally attached P and extends in the front-rear direction, and a wheel W that is pivotally supported in front of the wheel support arm 4.
An example of a movable abutment surface portion 3b provided behind the wheel support arm 4 and capable of abutment with the fixed abutment surface portion 3a, and an example of a fulcrum portion that is separated below the movable abutment surface portion 3b and extends in the left-right direction. Pressing lid part 6a facing with steel ball 5 shown
A coil spring 8, which is an example of a resilient means urged in the expansion direction with the upper end restricted by the pressing lid 6 a and the lower end restricted by the pressing base 6 b of the casing 7 facing up and down, The gap between the fixed abutment surface 3a and the pressing base 6b is set to a predetermined length through the mating surface 3a, the movable abutment surface 3b, the pressing lid 6a, and the pressing base 6b serving as the bottom surface of the casing 7. And an adjustment shaft 9.

[0003]

The swivel type caster has a structure that can freely swivel around a vertical swivel axis.
When subjected to an external force generated due to irregularities on the running road surface or obstacles such as pebbles, the vehicle behaves in an unstable manner, easily turns, and the bogie fluctuates or turns.

In the conventional swivel type caster shown in FIG.
Is located at a position orthogonal to the turning axis X, but since the pivot axis P and the rotation axis O of the wheel W are vertically separated from each other, it is difficult to maintain a stable direction restoring property. That is, as described with reference to FIG. 6B, when the wheel W rides on an obstacle during traveling, for example, an upward force F acts on the wheel W, and a component force as illustrated is generated based on the force F. . Obstacles and irregularities on the running road surface do not exist uniformly on the entire running road surface, but usually exist locally, so only one of the casters mounted on the left and right sides of the truck often rides . As a result, a horizontal component force is further generated due to the component force of the force F acting on the wheel W, and the wheel W is easily turned around the turning axis X. In the conventional device shown in FIG. 4A, the vertical separation distance between the pivot P and the axle O is inevitably long due to the structure of the shock absorbing mechanism. is there.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a revolving caster having a shock absorbing mechanism and having improved direction recovery so as not to turn unnecessarily even if there is an obstacle.

[0006]

SUMMARY OF THE INVENTION A swivel caster according to the present invention includes a mounting pedestal for fixing to a bogie frame, a swivel frame mounted to the mounting pedestal so as to be swivelable about a vertical swivel axis, and a swivel. A bracket that hangs from the frame, a swing arm that is swingably attached to the bracket via a horizontal fulcrum shaft, a wheel that is swingably attached to one end of the swing arm via a horizontal rotation shaft, and swinging. A damping mechanism interposed between the other end of the arm and the bracket, for urging the one end of the swing arm downward, and setting the fulcrum shaft and the rotation shaft at the same level. Thus, the above problem has been solved.

In a revolving caster, the wheels follow the traveling direction of the bogie due to the rolling resistance of the running wheels. This is a result of the moment load acting on the wheel due to the resistance of the road surface to the wheel. The moment load at this time is represented by the product of the length of the arm of the moment, that is, the horizontal distance from the ground contact point of the wheel (the rotation axis of the wheel) to the turning axis, and the magnitude of the resistance. Therefore, it is understood that the smaller the moment load, the more easily the wheel turns, and the more easily the wheel is affected by the external force. In other words, it can be said that the greater the moment load, the greater the turning resistance of the running wheels and the better the direction restoring property.

[0008] In order to suppress the lateral movement of the wheel, the vertical separation distance between the fulcrum axis of the swing arm and the rotation axis of the wheel is set within a range of about 20% of the wheel diameter, preferably zero. The same level means that they are within the range.

[0009] The shock absorbing mechanism absorbs and alleviates the impact or the like acting on the wheels by elastically biasing the one end of the swing arm downward, in other words, the wheels toward the traveling road surface, so as to move the wheels toward the bogie. It plays a role in preventing transmission. As a specific configuration, a connecting plate connecting between a pair of side plates forming a bracket and a connecting plate connecting between a pair of side plates forming a swing arm at the other end side of the swing arm are commonly used. It can be constituted by a penetrating shaft, a resilient member interposed between a washer attached to an end of the shaft protruding above the connecting plate of the bracket and the connecting plate of the bracket.

By interposing a resilient member between the connecting plate of the bracket and the connecting plate of the swing arm, swinging of the swingable swing arm in any direction is performed against the elastic force. As a result, it is possible to provide a revolving caster having a further improved cushioning effect and reduced vibration and impact.

As the resilient member, a compression coil spring or rubber or other elastic material can be used.

The fulcrum shaft can be arranged at a position offset in the horizontal direction with respect to the turning axis. However, the fulcrum shaft is made orthogonal to the vertical axis, and horizontal horizons for supporting the wheels are provided on both sides of the fulcrum shaft in the horizontal direction. By arranging the shaft and the central axis of the shock absorbing mechanism, it is possible to easily distribute the force and maintain a stable running of the caster.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

The revolving caster 10 shown in FIG.
4 to be attached to the frame of the bogie. For this purpose, the pedestal 14 is provided with a through hole 16 for inserting a mounting bolt (see FIG. 5). A pivot frame 18 is attached to the pedestal 12 via a ball bearing (not shown) so as to be rotatable around a vertical pivot axis X.
The above configuration is basically the same as the conventional swivel caster.

A bracket 20 is fixed to the revolving frame 18 by, for example, welding. As can be seen from FIG. 2, the bracket 20 includes a pair of parallel side plates 22 facing each other at a predetermined distance, and a connecting plate 24 connecting the side plates 22 to each other. The side plate 22 hangs down from the turning frame 18,
Near its lower end, it has through-holes that are horizontally aligned with each other. The connecting plate 24 extends horizontally and has a through hole near the center. In the drawings, a U-shaped member is attached to the side plate 22.
The case where the connection plate 24 was formed by welding to the edge of the above was illustrated.

A swing arm 30 is mounted via a horizontal fulcrum shaft O ₁ passing through a hole in the bracket 20.
The swing arm 30 can swing around the fulcrum shaft O _1. The swing arm 30 includes a pair of parallel side plates 32 facing each other, and a connecting plate 34 that connects the side plates 32 at one end of the swing arm 30. Each side plate 3
2 has a through hole for horizontally penetrating the fulcrum shaft O ₁ and a through hole for horizontally penetrating the axle O ₂ that supports the wheels 12. The connecting plate 34 has a through hole near the center thereof. As it can be seen from FIG. 3, a pair of pivot shafts O ₁ extends coaxially, the space for the wheel 12 is secured therebetween.

In the illustrated swivel type caster 10, the bolt 4
2 is the central axis of the buffer mechanism 40. That is, the shock absorbing mechanism 40 illustrated in the drawing has a bolt 42 that penetrates through the hole of the connecting plate 34 of the swing arm 30 and the hole of the connecting plate 24 of the bracket 20, and protrudes above the connecting plate 24. Washer 44 attached to end of bolt 42 and connecting plate 24
And a resilient member 46 made of rubber as an elastic material interposed therebetween. Note that a compression coil spring can be used as the elastic member 46 (see FIG. 5). The resilient member 46 is connected to the connecting plate 2 as shown in FIG.
In addition to the arrangement above the connection plates 24, 34, the arrangement may be made below the connection plates 24, 34, which also applies to the case of FIG. To prevent the nut 42b from loosening, the bolt 42
The case where the split pin 42b is inserted into the hole formed at the end of the bolt 42 is illustrated. However, when adjustment of elasticity and replacement of parts are not considered, the nut 42b is bolted to the bolt 42 by welding or swaging.
May be fixed permanently.

An elastic member 48 is interposed between the connecting plate 24 of the bracket 20 and the connecting plate 34 of the swing arm 30. This resilient member 48 may be made of rubber or another elastic material as shown as an elastic material, or may be replaced with a compression coil spring. By interposed between the elastic member 48 Haga connecting plate 24, 34, the swing arm 30 swings around the fulcrum axis O ₁ by the action from the state of the buffer mechanism 40 shown in FIG. 4 (B) to be described later The buffering effect at the time is obtained.

[0019] Fulcrum axis O₁In the horizontal direction around the center
Axle O at a position approximately equidistant to_TwoAnd loose
The action point of the collision mechanism 40 is arranged, and
Makes it easier to distribute the power and stabilize the casters.
Running can be maintained. Support buffer shaft O₁
And rotation axis O_TwoAlthough it is possible to place it between
, The fulcrum axis O₁The distance from the arm, that is, the length of the arm
It is necessary to increase the resilience of the resilient member 46 by the amount of shortening
There is.

[0020] FIG. 1A shows a state in which the wheels 12 are in contact with the ground.
doing. In this state, the fulcrum shaft O₁And rotation axis O_Two
And are horizontally aligned, that is, at the same level.

[0021] FIG. 4 shows another embodiment.
(A) corresponds to FIG. 1, (B) the wheel rides on an obstacle
It shows a sunk state. That is, the wheel 12 becomes an obstacle
When the user rides on the rocking arm 30, the resilient force of the resilient member 46 is applied.
Fulcrum axis O against₁Swing counterclockwise around the figure
You. At this time, the fulcrum shaft O₁And rotation axis O_TwoAnd the same level
, The rotation axis O_TwoTo
The acting force is a force that is almost directed upward. Therefore,
The swing arm 30 swings easily, and the wheel
It is difficult to generate the force to turn the. On the other hand, the fulcrum shaft
And the rotation axis is vertically separated (see FIG. 6),
As the wheel 12 runs over obstacles,
When an external force acts, it depends on the distance between the fulcrum shaft and the rotating shaft.
Component forces at various angles other than upward. The result
As a result, the wheels fluctuate, much less
It turns easily around the turning axis X.

[0022] The shaft 42 of the buffer mechanism 40 in FIG.
Has abolished the head of the hexagonal head bolt 42 shown in FIG.
Swing the two ends of the pin 42c through the end of the shaft 42
The arm 30 is supported by a side plate 32.

[0023] In the above embodiment, the fulcrum shaft O₁Is the pivot axis
X and therefore the ground point of the wheel 12 is
Although it is shifted from the intersection of the extension line of the rotation axis X and the traveling road surface,
As shown in FIG.₁Is horizontal to the rotation axis X
It may be offset in the direction.

[0024]

As is apparent from the above description, according to the present invention, by setting the fulcrum axis of the swing arm for supporting the wheel and the rotation axis of the wheel at the same level, the directional restorability of the wheel can be improved. Thus, it is possible to provide a swivel-type caster capable of ensuring stable traveling with less lateral movement of the bogie.

[Brief description of the drawings]

FIG. 1 is a front view of a revolving caster.

FIG. 2 (A) is a right side view of the swivel caster of FIG. 1,
(B) is a left side view of the revolving caster of FIG. 1.

FIG. 3 is a sectional view of a fulcrum shaft portion of the revolving caster of FIG. 1;

FIG. 4 is a partially broken front view of a revolving caster showing another embodiment.

FIG. 5 is a perspective view of a revolving caster showing another embodiment.

FIG. 6A is a partially cutaway front view showing a conventional technique;
(B) is a diagram showing the direction of force.

[Explanation of symbols]

10 Swivel caster 12 Wheels 14 Mounting base 18 Swivel frame 20 Bracket 22 Side plate 24 Connecting plate 30 Swing arm 32 Side plate 34 Connecting plate 40 Buffer mechanism 46 Resilient member 48 Resilient member X Revolving axis O ₁ fulcrum axis O ₂ rotating axis

Claims (4)

[Claims] 1. A mounting base for fixing to a frame of a bogie, a revolving frame mounted on the mounting base so as to be rotatable about a vertical revolving axis, a bracket suspended from the revolving frame, and a fulcrum horizontal to the bracket. A swing arm that is swingably mounted via a shaft, a wheel rotatably mounted on one end of the swing arm via a horizontal rotating shaft, and an interposition between the other end of the swing arm and the bracket A caster, comprising: a buffer mechanism for urging the one end of the swing arm downward, wherein the fulcrum shaft and the rotation shaft are set at the same level. 2. A connecting plate connecting the buffer mechanism to a pair of side plates forming the bracket, and a connecting plate connecting the pair of side plates forming the swing arm at the other end of the swing arm. And a resilient member interposed between a washer attached to an end of the shaft protruding above the connecting plate of the bracket and a connecting plate of the bracket. . 3. A resilient member is interposed between the connecting plate of the bracket and the connecting plate of the swing arm.
Swivel caster. 4. The swivel caster according to claim 2, wherein said resilient member is formed of a compression coil spring or an elastic material.