JPH05246204A - Castor - Google Patents

Abstract

PURPOSE: To provide a castor incorporating means whereby such impact stresses as to cause damage can be accommodated or resisted. CONSTITUTION: In a castor in which the yoke 22 of a wheel-bearing body 20 has a bore within which a mounting head 1 is journalled for swivelling by bearings 10, 25, the bearings are protected against damage due to force tending to twist the body on axes transverse to the swivel axis by provision of surfaces on the head and the body which are closely spaced to limit such twisting. The bore can be restricted by a sleeve or washer 50 held on the head 1 and/or by a sleeve 42 extending into the bore from a cap or cover 40 closing one end of the bore.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to casters, and more particularly to casters for supporting articles such as wheelchairs, wheelbarrows in supermarkets and airports, which are susceptible to fairly high impact forces as a result of use and misuse.

[0002]

Such articles fall on the wheel (s) of the caster, one wheel of the caster, or the caster body bearing one or more wheels and are generally horizontal. Impact may occur. In either case, the caster body tends to rotate relative to the mounting head that mounts the caster on the article. As a result of such an impact force, the caster bearing may generate a large stress, and may be damaged so as to impair the swivel property, or even the caster may be broken so as to fall off. It is an object of the present invention to provide a caster mounting means that can withstand or withstand such impact stress.

[0003]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a caster head for mounting the caster on an article to be supported, a caster body for supporting one or more wheels for rotation about the axle, and an axle. Bearings for mounting the caster body on the mounting head so as to swivel about a vertical swivel axis spaced from and relative twisting or rotational movement of the caster body and mounting head about an axis transverse to this swivel axis. And a means for supporting the bearing by limiting the bearing. Accordingly, the support means provides a stop or shock cushion between the caster body and the mounting head at one or more locations axially spaced from the bearing along the pivot axis to limit relative pivotal movement. Function as a container.

This support means can be provided in various ways. For example, it can be provided, for example, by forming intimately close coaxial columnar surfaces of the caster body and mounting head above and / or below the bearing. Alternatively, a sleeve or tubular member can be provided in the space between the faces. Any twisting action experienced by the bearing about the transverse axis is resisted either directly by the post or by the sleeve member. Although the sleeve member is squeezed between its faces, it tends to hold the faces in a coaxial or proper relationship. Such sleeves or washers are preferably arranged axially between the upper or lower caps or covers which protect the bearings from dust and protect the bearings themselves, or with integral parts of those caps or covers. Can be done.

British Patent Publication No. 2 240 266, the contents of which are hereby incorporated by reference, describes an abnormal vibration or shimmy of the caster by increasing the friction between the mounting head and the caster body. Various means of preventing or reducing are described. The support means of the present invention likewise can suitably generate such friction against swiveling. The support means thus includes an elongated washer or sleeve having a portion shaped to frictionally engage the caster body and mounting head. The friction portion has an annular disc portion at one end of the sleeve which engages at its outer edge with the face of the body transverse to the pivot axis. The sleeve is frictionally or mechanically mounted so that it is clamped against rotation with respect to the mounting head.

It will be appreciated that the present invention provides a very simple and therefore cost effective means of increasing the caster's resistance to impact forces.

The invention is explained in more detail below by way of example with reference to the accompanying drawings. In the accompanying drawings, there is shown a partial cross-sectional side view of an embodiment of the caster of the invention.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The illustrated caster includes a caster mounting head 1. The mounting head 1 allows the caster to be mounted on a wheelchair or other item to be supported. The head 1 includes a shaft or shank having a threaded upper end portion 2 which can be received in a tapered recess formed in a wheelchair. Below this top part 2,
A hexagonal portion 4 having a large diameter is provided, and on the lower side of the hexagonal portion 4, an upper circular columnar portion 5 and a lower circular columnar portion 6 having a slightly smaller diameter are arranged, and an annular step portion 7 is formed. It is formed between these two columnar portions. The head 1 has a thread groove portion 9 at its lower end.

The tubular inner ball race 10 of the high quality ball bearing is received on the lower columnar portion 6 and held in place between the step 7 and the washer 11. A washer 11 is received between this race and a hexagonal nut 12, which is received on the threaded lower end portion 9 of the head. A rivet structure may be used instead of the nut 12.

The caster also includes a caster body 20. The caster body 20 has a pair of side arms 21, only one of which is visible. These side arms 21 extend downwardly from the yoke 22 and support the caster wheels 24 between them at their lower ends. The yoke 22 has a vertical hole in which the outer race 25 of the ball bearing is fixed in a groove 26 formed in the wall of the hole. The caster body 20 may be molded from a plastic material and the outer ball race 25 may then be integrally molded to the yoke 22. The axis of the ball bearing defines the vertical swivel axis of the caster about which the caster body 20 can swivel with respect to the mounting head 1.

The caster also includes an annular top cap or cover 30. This cap or cover protects the ball bearings from ingress of dust. The cover 30 can be molded with a plastic material, and has an annular main portion 31 having a hexagonal inner peripheral surface that engages with the head of the hexagonal portion 4 of the head 1, and a columnar portion 5.
A lower and inner stepped portion 32 extending underneath the hexagonal portion. Main part 31 at its outer edge
Has a downward skirt portion. The skirt portion surrounds the upper end of the yoke 22.

To enclose the bearing from below, a generally saucer-shaped lower cap or cover 40 is provided. The cover 40 has a bottom wall 41 from which a skirt portion 42 extends upwardly to be partially received within the lower portion of the hole in the yoke 22. The hole and skirt portion 42 is shaped to snap fit, for example, by the outer bead 44 at the upper end of the skirt portion being received in a groove in the hole. The flange 45 protruding outward of the skirt portion abuts the lower surface of the yoke.

According to the present invention, it is sufficient that the radial thickness of the skirt portion 42 be such that its inner surface is closely spaced from the nut 12. If a rivet structure is used instead of the nut 12, the inner surface is reshaped to form the proper close spacing. Also, according to the present invention, the sleeve or washer 50 is
And is closely spaced from the cylindrical surface around the hole in the yoke 22. The washer 50, which may be molded of plastic material, is axially retained between the top cover 30 and the upper edge of the inner race 10. The inner race 10 extends outwardly in the hole of the yoke 22 beyond the step 7.

If the caster shown has to be dropped almost vertically, the mounting head will tend to rotate relative to the caster body 20 as indicated by arrow A. This is because the wheel axis, and thus the lowest position of the wheel, is laterally offset from the turning axis.

The upper end of the washer 50 engages between the yoke 22 and the portion 5 to severely constrain any of the above mentioned rotations across the pivot axis so that the ball bearing is sufficient to break the outer race. It is designed to limit the stress generated in the. Similarly, the skirt portion 42 of the cover 40 engages between the nut 12 and the hole in the yoke 22 to resist rotational forces. The skirt portion 42 and washer 50, of course, protect the bearing against any other forces that tend to cause relative rotation.

The washer 50 is provided at its upper end with an elastic annular disk portion 51 extending outwardly opposite to the abnormal vibration or shimmy of the caster. The disk portion 51 overlaps with the upper end of the yoke 22 and is engaged with the yoke 22 by a ridge 52 extending downward. The washer 50 frictionally engages the columnar portion 5 or is clamped to the mounting head 1 so as to prevent relative rotation.
This frictionally resists pivoting of the caster body on the mounting head by the engagement of the rim 52 with the upper end of the yoke 22.

The present invention may, of course, be embodied in various ways other than as specifically described and shown. For example, washer 5
Zero can be an integral part of the top cover 30 and friction against pivoting can be provided by the cover 40.

[Brief description of drawings]

FIG. 1 is a partially sectional side view of an embodiment of a caster according to the present invention.

[Explanation of symbols] 1 mounting head 2 upper end portion with screw groove 4 hexagonal portion 5,6 columnar portion 7 step portion 9 screw groove portion 10 inner race of ball bearing 11 washer 12 nut 20 caster body 21 side arm 22 yoke 24 Wheel 25 Ball bearing outer race 26 Groove 30,40 Cover or cap 31 Main part 41 Lower end wall 42 Skirt part 44 Bead 45 Flange 50 Support means or sleeve or washer 51,52 Disc part

Claims (9)

[Claims] 1. A mounting head (1) for mounting a caster on an article to be supported, a caster body (20) for supporting one or more wheels (24) for rotation about the axle, and an axle. Bearings (10, 25) for mounting the caster body on a mounting head for swiveling about spaced vertical swivel axes, the caster body (2) around an axis transverse to said swivel axis.
0) and a caster characterized in that it is arranged to limit or prevent relative twisting or rotational movement of the mounting head (1). 2. A caster according to claim 1, wherein at least axially spaced from the bearing (10, 25) along a pivot axis whose twisting or rotational movement limits relative twisting. Caster body (2
0) and casters characterized by being limited or blocked by support means (42; 50) received between the mounting head (1). 3. A caster according to claim 2, wherein the support means is at least one tubular member (42; 50) between adjacent coaxial surfaces of the caster body (20) and the mounting head (1). ) A caster characterized by comprising. 4. The caster according to claim 3, wherein the adjacent coaxial surfaces are constituted by a columnar portion of the mounting head (1) and a hole in the caster body for receiving the shaft portion and the bearing (10, 25). Casters that are characterized by being. 5. The caster according to claim 3 or 4, further comprising: a tubular member serving as a skirt portion (42) of the cover (40) for protecting the bearing from dust and dirt. Casters characterized by. 6. The caster according to claim 3, 4, or 5, wherein the bearing and a cap for protecting the bearing (10, 25) from dust and dirt, that is, A caster having a tubular member which is a washer (50) arranged in the axial direction of the cover (30). 7. A caster according to any one of the preceding claims, in which the support means (50) provide frictional resistance to the swiveling of the caster body (20) on the mounting head (1). A caster characterized by that. 8. A caster according to claim 7, characterized in that the support means (50) are shaped to frictionally engage both the caster body (20) and the mounting head (1). caster. 9. A caster according to claim 2, 3, or 4, wherein the supporting means comprises a sleeve (50) around the columnar part (5) of the mounting head (1). ) And having an annular disc portion (51, 52) at one end of the sleeve which frictionally engages at the outer edge of the face of the caster body (20) transverse to the pivot axis for mounting the sleeve. A caster characterized by being held frictionally or mechanically so as not to rotate with respect to the head.