GB2156889A

GB2156889A - Tread construction

Info

Publication number: GB2156889A
Application number: GB08409065A
Authority: GB
Inventors: Anthony Corbett
Original assignee: Beldray Ltd
Current assignee: Beldray Ltd
Priority date: 1984-04-07
Filing date: 1984-04-07
Publication date: 1985-10-16
Also published as: GB2156889B; GB8409065D0

Abstract

A tread construction for a ladder is shown in Figure 1 and includes angle section load bearing treads supports extending as rungs, and a lightweight, non-load bearing covering carried by the supports. This enables the tread construction costs to be substantially reduced. <IMAGE>

Description

SPECIFICATION Tread constructions This invention relates to tread constructions for articles such as step ladders, step stools, combination ladders, extension ladders and the like (which articles are hereinaftergenerically referred to as "ladders").

The object ofthe present invention isto provide a tread construction which is economical to manufac ture in terms of material costs, especially when compared with conventional aluminium ladders.

According to the present invention a ladder tread construction comprises at least one metal support member spanning the space between the ladder stiles and a tread surface provided buy a metal plate covering and supported by said support member.

In practice, the metal plate may be an aluminium extrusion or a steel plate which is not inherently load bearing in terms ofthe loads normally catered for in ladder constructions. This is possible because the load bearing requirements can be met by the support members. Thus, the metal plate may have a largely decorative function whilst allowing a robust tread construction to be achieved at relatively low cost, especially if the stiles and support members are fabricated from steel.

In the preferred form ofthe invention, each metal plate covers and is supported by a pair of support members located on opposite sides of the stiles such that the metal plate bridges the gap between the support members.

The support members in the preferred embodiment are of angle section and one limb thereof may be projection (or otherwise) welded to the stiles so that the other limb projects away from the stiles. The metal plate is conveniently flanged along its edges so that the flanges conceal the free edges of the projecting limbs ofthe support members. The metal plate may be secured in place on the pair of support members by a snap-fit action and the flanges may be crimped to the projecting limbs ofthe supporting members.

The exposed ends of the support members and the metal plates may, if desired, be concealed by means of end caps which may be formed as plastics mouldings for example.

One embodiment ofthe invention will now be described byway of example only with reference to the accompanying drawings, in which: Figure 1 is a fragmentary perspective view showing a ladder construction in accordance with the invention as incorporated in for example step ladders; and Figure 2 is a sectional viewshowing the configuration of the metal plate which affords the tread surface.

As shown,the tread construction comprises a pair of angle section cross members 10 secured to opposite faces of the stiles 12 (as by projection weiding for example) so that at each tread level, the spacing between the stiles is spanned by a respective pair of cross members 10. The stiles 12 are conveniently fabricated from steel tube and the cross members 10 are also of steel and have sufficient strength so as to fulfill the load bearing requirements of the ladders.

A metal plate 14 covers and is supported by each pair of cross members 10 so as to provide the tread surface. The metal plate 14 may be a thin aluminium extrusion which, by itself, would be incapable of meeting the load bearing requirements. Alternatively the plate 14 may be a thin steel sheet.

As shown in Figure 2, the plate is formed with inwardly angled flanges 16 along each edge which, because the material is thin, can flex elastically to some degree thus enabling the plate to be snap fitted onto the cross members 10 so that the flanges 16 conceal the free edges of the cross members.

To secure the plate 1 4firmly in place, the flanges may be crimped to the support members 10 at suitable locations, e.g. as indicated by reference numeral 18.

The cross members may be trimmed attheirendsas shown to avoid any potentially dangerous sharp points or, if desired, the exposed ends of the treads may be concealed by end caps of for example plastics material.

1. A laddertread construction comprising at least one metal support member spanning the space between the ladder stiles, and a tread surface provided buy a metal plate covering and supported bysaid support member.

2. A ladder tread construction as claimed in Claim 1 wherein a pair of angle section metal support members span the space between the ladder stiles, located respectively on opposite sides of the stiles.

3. A ladder tread construction as claimed in Claim 1 or Claim 2 wherein the metal support member is/are of steel.

4. A ladder tread construction as claimed in any preceding claim wherein the metal plate covering is secured in place by a snap-fit action and crimped for security.

5. A laddertread construction substantially as described with reference to the accompanying drawing.

Amendmentstothe claims have been filed, and havethefollowing effect: Claims 1-5 above have been deleted.

New claims have been filed as follows:- CLAIMS 1. A laddertread construction comprising a pair of angle section metal support members which span the space between the ladder stiles, located respectively on opposite sides of the stiles, and a tread surface provided by a metal plate covering and supported by said support members.

2. A laddertread construction as claimed in Claim 1 wherein the metal support members are of steel.

3. A ladder tread construction as claimed in any preceding claim wherein the metal plate covering is secured in place by asnap-fit action and crimped for

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Tread constructions This invention relates to tread constructions for articles such as step ladders, step stools, combination ladders, extension ladders and the like (which articles are hereinaftergenerically referred to as "ladders"). The object ofthe present invention isto provide a tread construction which is economical to manufac ture in terms of material costs, especially when compared with conventional aluminium ladders. According to the present invention a ladder tread construction comprises at least one metal support member spanning the space between the ladder stiles and a tread surface provided buy a metal plate covering and supported by said support member. In practice, the metal plate may be an aluminium extrusion or a steel plate which is not inherently load bearing in terms ofthe loads normally catered for in ladder constructions. This is possible because the load bearing requirements can be met by the support members. Thus, the metal plate may have a largely decorative function whilst allowing a robust tread construction to be achieved at relatively low cost, especially if the stiles and support members are fabricated from steel. In the preferred form ofthe invention, each metal plate covers and is supported by a pair of support members located on opposite sides of the stiles such that the metal plate bridges the gap between the support members. The support members in the preferred embodiment are of angle section and one limb thereof may be projection (or otherwise) welded to the stiles so that the other limb projects away from the stiles. The metal plate is conveniently flanged along its edges so that the flanges conceal the free edges of the projecting limbs ofthe support members. The metal plate may be secured in place on the pair of support members by a snap-fit action and the flanges may be crimped to the projecting limbs ofthe supporting members. The exposed ends of the support members and the metal plates may, if desired, be concealed by means of end caps which may be formed as plastics mouldings for example. One embodiment ofthe invention will now be described byway of example only with reference to the accompanying drawings, in which: Figure 1 is a fragmentary perspective view showing a ladder construction in accordance with the invention as incorporated in for example step ladders; and Figure 2 is a sectional viewshowing the configuration of the metal plate which affords the tread surface. As shown,the tread construction comprises a pair of angle section cross members 10 secured to opposite faces of the stiles 12 (as by projection weiding for example) so that at each tread level, the spacing between the stiles is spanned by a respective pair of cross members 10. The stiles 12 are conveniently fabricated from steel tube and the cross members 10 are also of steel and have sufficient strength so as to fulfill the load bearing requirements of the ladders. A metal plate 14 covers and is supported by each pair of cross members 10 so as to provide the tread surface. The metal plate 14 may be a thin aluminium extrusion which, by itself, would be incapable of meeting the load bearing requirements. Alternatively the plate 14 may be a thin steel sheet. As shown in Figure 2, the plate is formed with inwardly angled flanges 16 along each edge which, because the material is thin, can flex elastically to some degree thus enabling the plate to be snap fitted onto the cross members 10 so that the flanges 16 conceal the free edges of the cross members. To secure the plate 1 4firmly in place, the flanges may be crimped to the support members 10 at suitable locations, e.g. as indicated by reference numeral 18. The cross members may be trimmed attheirendsas shown to avoid any potentially dangerous sharp points or, if desired, the exposed ends of the treads may be concealed by end caps of for example plastics material. CLAIMS

4. A ladder tread construction substantially as described with reference to the accompanying drawing.

New claims have been filed as follows:- CLAIMS

1. A laddertread construction comprising a pair of angle section metal support members which span the space between the ladder stiles, located respectively on opposite sides of the stiles, and a tread surface provided by a metal plate covering and supported by said support members.

3. A ladder tread construction as claimed in any preceding claim wherein the metal plate covering is secured in place by asnap-fit action and crimped for security.