GB2064955A - Castoring wheels - Google Patents

Abstract

A castoring wheel assembly (10) comprises a wheel (11) rotatably mounted on a body (13) itself rotatable about a mounting post (16) extending transversely of and offset relative to the axis (12) of rotation of the wheel (11). The cooperating bearing surfaces (14,15) of the body (13) and mounting post (16) have a generatrix (18) which passes through the point or line of contact (17) of the wheel (11) on the ground so as to allow for castoring in a leading or trailing position. The cooperating bearing surfaces (14,15) are conical, having a cone apex located above the level of the axis of rotation (12) of the wheel (11) so as to reduce the tendency to shimmy. <IMAGE>

Description

SPECIFICATION Castoring wheels This invention relates to castoring wheel assemblies such as are commonly fitted to furniture, trolleys, wheelchairs and other heavy articles which are required to be moved from time to time.

Known castoring wheel assemblies comprise a wheel rotatably mounted on the end, or within the fork end, of a mounting post, or a pair of wheels rotatably mounted on opposed sides of the mounting post. In each case the mounting post is mounted on a support structure so as to be rotatable about a vertical axis which is offset in relation to the point or points of contact of the wheel or wheels with the ground, and this offset causes the wheel or wheels to move to a trailing position when the furniture or other load is moved in any direction. However with such castoring wheels a considerable effort is required to move the load if the direction of intended movement is substantially in alignment with the leading direction of the wheel or wheels.Also because of the relatively large offset used in an effort to reduce the aforementioned considerable effort the wheels tend to 'shimmy' or vibrate as the load is moved. Such shimmying causes undue wear on the floor surface and on the bearings or bearing surfaces of the castor assembly, and makes guiding of the load difficult.

It is an object of the present invention to provide a castoring wheel assembly in which the above disadvantages are avoided or at least minimised. The invention provides a castoring wheel assembly comprising a wheel part mounted on a body part for rotation relative thereto about a first axis, said body part having a bearing surface adapted for cooperation with a bearing surface on a mounting post, said mounting post extending along a second axis transversely of and offset in relation to said first axis and the generatrix of said body part bearing surface passing through the point of contact of said wheel part with the ground.

The bearing surfaces are preferably complementary and may be conical, in which case the cone angle and the height of the apex of the cone above the ground are chosen in relation to each other so that the generatrix of the cone passes through the point of contact of the wheel part with the ground.

Preferably the apex of the cone lies above a horizontal plane passing through the axis of rotation of the wheel part.

The invention will now be further described with reference to the accompanying drawing in which Figure lisa vertical sectional elevation of one embodiment; Figure 2 is a vertical sectional elevation of the embodiment of Figure 1 taken at right angles thereto; and Figure 3 is a plan view of the embodiment of Figures 1 and 2.

The Figures show a castoring wheel assembly 10 comprising a wheel part 11 which is mounted on a body part 13 and is rotatable about a horizontal axis 12. The body part 13 has formed therein a conical bore 14 in which is received the conical end 15 of mounting post 16 whereby the body part 13 is rotatable about the axis of the post 16. The generatrix 18 of the conical bore 14 passes through the point of contact 17 of the wheel part 11 with the ground.

A castoring wheel assembly having the above described construction will castor in a leading or trailing position, thus obviating the need for applying a large force to the load in order to cause the wheel assembly to move from a leading to a trailing position. Also the effect of the mounting post 16 being forced into the conical bore 14 reduces the tendency for the wheel assembly to shimmy or vibrate as the load is moved. The present castoring wheel assembly also requires less space than for example, the castoring wheels as applied to wheelchairs.

1. A castoring wheel assembly comprising a wheel part mounted on a body part for rotation relative thereto about a first axis, said body part having a bearing surface adapted for cooperation with a bearing surface on a mounting post, said mounting post extending along a second axis disposed transversely of and offset in relation to said first axis, and a generatrix of the bearing surface of said body part passing through the point or line of contact of said wheel part with a surface on which said wheel part in use rolls.

2. An assembly according to claim 1 wherein said bearing surfaces are complementary.

3. An assembly according to claim 2 wherein said bearing surfaces are conical.

4. As assembly according to claim 3 wherein the apex of the cone of said conical surfaces lies above a plane passing through the axis of rotation of said wheel part parallel with the surface on which said wheel part in use rolls.

5. A castoring wheel assembly substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Castoring wheels This invention relates to castoring wheel assemblies such as are commonly fitted to furniture, trolleys, wheelchairs and other heavy articles which are required to be moved from time to time. Known castoring wheel assemblies comprise a wheel rotatably mounted on the end, or within the fork end, of a mounting post, or a pair of wheels rotatably mounted on opposed sides of the mounting post. In each case the mounting post is mounted on a support structure so as to be rotatable about a vertical axis which is offset in relation to the point or points of contact of the wheel or wheels with the ground, and this offset causes the wheel or wheels to move to a trailing position when the furniture or other load is moved in any direction. However with such castoring wheels a considerable effort is required to move the load if the direction of intended movement is substantially in alignment with the leading direction of the wheel or wheels.Also because of the relatively large offset used in an effort to reduce the aforementioned considerable effort the wheels tend to 'shimmy' or vibrate as the load is moved. Such shimmying causes undue wear on the floor surface and on the bearings or bearing surfaces of the castor assembly, and makes guiding of the load difficult. It is an object of the present invention to provide a castoring wheel assembly in which the above disadvantages are avoided or at least minimised. The invention provides a castoring wheel assembly comprising a wheel part mounted on a body part for rotation relative thereto about a first axis, said body part having a bearing surface adapted for cooperation with a bearing surface on a mounting post, said mounting post extending along a second axis transversely of and offset in relation to said first axis and the generatrix of said body part bearing surface passing through the point of contact of said wheel part with the ground. The bearing surfaces are preferably complementary and may be conical, in which case the cone angle and the height of the apex of the cone above the ground are chosen in relation to each other so that the generatrix of the cone passes through the point of contact of the wheel part with the ground. Preferably the apex of the cone lies above a horizontal plane passing through the axis of rotation of the wheel part. The invention will now be further described with reference to the accompanying drawing in which Figure lisa vertical sectional elevation of one embodiment; Figure 2 is a vertical sectional elevation of the embodiment of Figure 1 taken at right angles thereto; and Figure 3 is a plan view of the embodiment of Figures 1 and 2. The Figures show a castoring wheel assembly 10 comprising a wheel part 11 which is mounted on a body part 13 and is rotatable about a horizontal axis 12. The body part 13 has formed therein a conical bore 14 in which is received the conical end 15 of mounting post 16 whereby the body part 13 is rotatable about the axis of the post 16. The generatrix 18 of the conical bore 14 passes through the point of contact 17 of the wheel part 11 with the ground. A castoring wheel assembly having the above described construction will castor in a leading or trailing position, thus obviating the need for applying a large force to the load in order to cause the wheel assembly to move from a leading to a trailing position. Also the effect of the mounting post 16 being forced into the conical bore 14 reduces the tendency for the wheel assembly to shimmy or vibrate as the load is moved. The present castoring wheel assembly also requires less space than for example, the castoring wheels as applied to wheelchairs. CLAIMS

1. A castoring wheel assembly comprising a wheel part mounted on a body part for rotation relative thereto about a first axis, said body part having a bearing surface adapted for cooperation with a bearing surface on a mounting post, said mounting post extending along a second axis disposed transversely of and offset in relation to said first axis, and a generatrix of the bearing surface of said body part passing through the point or line of contact of said wheel part with a surface on which said wheel part in use rolls.

2. An assembly according to claim 1 wherein said bearing surfaces are complementary.

3. An assembly according to claim 2 wherein said bearing surfaces are conical.

4. As assembly according to claim 3 wherein the apex of the cone of said conical surfaces lies above a plane passing through the axis of rotation of said wheel part parallel with the surface on which said wheel part in use rolls.

5. A castoring wheel assembly substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.