GB2061365A - Expanding plug castor - Google Patents

Abstract

A castor has a rolling support member set in a carrier having a peg engageable in a socket of the item to be supported by the castor, the peg 6 carrying partly nested elements 7 whose degree of nesting and thereby their radial projection relative to the peg can be varied to grip the interior of the socket by adjusting the distance between two abutments between which the partly nested elements lie. <IMAGE>

Description

SP ECIFICATION Expanding plug castor The invention relates to castors of the kind in which a peg is provided which wi! be received in a socket in the equipment to which the castor is to be fitted. The castor may be of the swivel type or of the "fixed" i.e., non-swivelling, type.

As legs or sockets of various sizes require castors, it has been necessary in the past to provide a multiplicity of peg sizes, or to use pegs that can be expanded to suit the particular leg or socket involved.

Most sxpandable pegs comprise a stem carrying a sleeve of steel or plastic expandable by screwing toward each other a conical member in each end. Instead of a sleeve which is radially expandable, a compressible sleeve of rubber may be used which will radially expand on axial compression.

The first tvpe of sleeve is robust but heavy and relatively expensive to produce, while rubber sleeves are much cheaper but much weaker from a load carrying point of view.

According to this invention there is provided a castor having a peg which receives a plurality of partially nesting expander elements located between two abutments which ars adjustable towards one another to cause the elements to nest to a greater degree and thereby radiaily expand and engage in a socket in which the peg and elements are receivable.

In order that the invention may be more clearly understood two embodiments, given by way of example oniy, will now be described with reference to the accompanying drawings, wherein: Figure 1 is a side elevation drawing of a castor for engaging a square socket; Figure 2 is a side elevation of the same castor partly sectioned on the vertical centre line; Figure 3 is a side elevation and plan view of one of the expander elements of Figures 1 and 2; Figure 4 is a side elevation and plan view of an alternative expander elements of round sockets, and Figure 5 is a partially sectioned elevation of an alternative arrangement of expander elernents on a peg of a castor.

In Figures 1 and 2 is shown a swivel castor having a swivelling fork 1 carrying a wheel 1. A top cup 3 on the fork has a hole 4 at its centre, in which is assembled a bolt 5.

On shank 6 of the bolt which forms the peg of the castor and which protrudes above the top cup, is assembled a number of expander elements 7 each having a hole 8 in the centre of such a size as to be a free fit on the bolt shank 6.

Figures 3 and 4 show respectively two forms of expander elements. Each has sides 9 that taper inwards towards a bottom 10 so that the outside dimension across the bottom corners 11 is not greater than the inside dimension across the top 12, whereby the expander elements when assembled one above the other as shown partially nest.

At the top of the stack of expander elements is assembled a nut 1 3 with conical sides 14.

The nut screws on to thread 1 5 provided at the top of the bolt and is screwed finger tight into the top expander element until the external cone of the nut nests in the top expander element. When the assembly as described is inserted into the socket in the equipment and the bolt 5 is tightened with a suitable spanner, the cone is forced into the top expander element, forces and thereby spreads the top edges 1 6 of that element outwards until they engage the walls of the socket Once the top expander ele lament reaches this stage, continued tightening o,- the bolt 5 causes all the elements to nest more deeply intro each other until all edges 1 6 engage the hole walls.

By varying the side and shape of the expander elements, castors can be provided to suit a wide variety of hole shapes and sizes.

Because the top expander element grips the socket first, tightening the bolt after this has the effect of pulling the castor into the socket and against the mounting surface of the equipment.

This gives a more rigid connection than with most existing types of expanding steel or rubber sleeves.

Referring to Figure 5 an arrangement of expander elements is shown where they are stacked open face down and an expander cone is provided on the twist sap of the castor.

The embodiments described are relatively cheap, and yet robust

CLAIMS 1. A castor having a rotatable support member in a carrier having a peg for engagement in a socket of that to which the castor is to provide rolling support, a plurality of partially nesting expander elements received by tile peg, each element expendable radially of the peg by urging an adjacent element into greater nesting engagement, and abutments between which the elements are located exislly of the peg, means being provided to vary the distance between the abutments and thereby the degree of nesting and thus the degree of radial projection of the elements relative to the peg axis.

2. A castor according to Claim 1 in which the elements taper inward from an open end toward a closed end having an aperture in the closed end to receive the peg.

3. A castor according to either of the preceding claims in which the open ends of the eieir elements are directed away from the rntetable support member.

4. A castor according to claim 5 in which that abutment engaging the open end of the endmost element in which not other element nests ie a relatively rigid frusto conical abutment having a threaded bore engaging a thread on the peg.

5. A castor according to any of thy preceding

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

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SP ECIFICATION Expanding plug castor The invention relates to castors of the kind in which a peg is provided which wi! be received in a socket in the equipment to which the castor is to be fitted. The castor may be of the swivel type or of the "fixed" i.e., non-swivelling, type. As legs or sockets of various sizes require castors, it has been necessary in the past to provide a multiplicity of peg sizes, or to use pegs that can be expanded to suit the particular leg or socket involved. Most sxpandable pegs comprise a stem carrying a sleeve of steel or plastic expandable by screwing toward each other a conical member in each end. Instead of a sleeve which is radially expandable, a compressible sleeve of rubber may be used which will radially expand on axial compression. The first tvpe of sleeve is robust but heavy and relatively expensive to produce, while rubber sleeves are much cheaper but much weaker from a load carrying point of view. According to this invention there is provided a castor having a peg which receives a plurality of partially nesting expander elements located between two abutments which ars adjustable towards one another to cause the elements to nest to a greater degree and thereby radiaily expand and engage in a socket in which the peg and elements are receivable. In order that the invention may be more clearly understood two embodiments, given by way of example oniy, will now be described with reference to the accompanying drawings, wherein: Figure 1 is a side elevation drawing of a castor for engaging a square socket; Figure 2 is a side elevation of the same castor partly sectioned on the vertical centre line; Figure 3 is a side elevation and plan view of one of the expander elements of Figures 1 and 2; Figure 4 is a side elevation and plan view of an alternative expander elements of round sockets, and Figure 5 is a partially sectioned elevation of an alternative arrangement of expander elernents on a peg of a castor. In Figures 1 and 2 is shown a swivel castor having a swivelling fork 1 carrying a wheel 1. A top cup 3 on the fork has a hole 4 at its centre, in which is assembled a bolt 5. On shank 6 of the bolt which forms the peg of the castor and which protrudes above the top cup, is assembled a number of expander elements 7 each having a hole 8 in the centre of such a size as to be a free fit on the bolt shank 6. Figures 3 and 4 show respectively two forms of expander elements. Each has sides 9 that taper inwards towards a bottom 10 so that the outside dimension across the bottom corners 11 is not greater than the inside dimension across the top 12, whereby the expander elements when assembled one above the other as shown partially nest. At the top of the stack of expander elements is assembled a nut 1 3 with conical sides 14. The nut screws on to thread 1 5 provided at the top of the bolt and is screwed finger tight into the top expander element until the external cone of the nut nests in the top expander element. When the assembly as described is inserted into the socket in the equipment and the bolt 5 is tightened with a suitable spanner, the cone is forced into the top expander element, forces and thereby spreads the top edges 1 6 of that element outwards until they engage the walls of the socket Once the top expander ele lament reaches this stage, continued tightening o,- the bolt 5 causes all the elements to nest more deeply intro each other until all edges 1 6 engage the hole walls. By varying the side and shape of the expander elements, castors can be provided to suit a wide variety of hole shapes and sizes. Because the top expander element grips the socket first, tightening the bolt after this has the effect of pulling the castor into the socket and against the mounting surface of the equipment. This gives a more rigid connection than with most existing types of expanding steel or rubber sleeves. Referring to Figure 5 an arrangement of expander elements is shown where they are stacked open face down and an expander cone is provided on the twist sap of the castor. The embodiments described are relatively cheap, and yet robust CLAIMS

1. A castor having a rotatable support member in a carrier having a peg for engagement in a socket of that to which the castor is to provide rolling support, a plurality of partially nesting expander elements received by tile peg, each element expendable radially of the peg by urging an adjacent element into greater nesting engagement, and abutments between which the elements are located exislly of the peg, means being provided to vary the distance between the abutments and thereby the degree of nesting and thus the degree of radial projection of the elements relative to the peg axis.

2. A castor according to Claim 1 in which the elements taper inward from an open end toward a closed end having an aperture in the closed end to receive the peg.

3. A castor according to either of the preceding claims in which the open ends of the eieir elements are directed away from the rntetable support member.

4. A castor according to claim 5 in which that abutment engaging the open end of the endmost element in which not other element nests ie a relatively rigid frusto conical abutment having a threaded bore engaging a thread on the peg.

5. A castor according to any of thy preceding claims in which the elements each comprise a base forming the closed end and a plurality of sides independent of each other and integral with the base.

6. A castor substantially as herein described with reference to the accompanying drawings.