GB2185775A - Ladder - Google Patents

Abstract

A ladder is provided with a tread 16 which is made as an injection moulding of a plastics material and which is arranged to be snap-engaged with the ladder stiles so as to give particularly cheap but satisfactory manufacturing and assembly method. <IMAGE>

Description

SPECIFICATION Ladder This invention relates to ladders, including within its scope such similarconstructions as steps, step stools and the like.

According to the invention a ladder comprises two stiles, a rung extending therebetween, and a tread located adjacent the rung, characterised in that the tread comprises a plastics moulding having aligned recesses at respective ends to receive the respective stiles in engagement therein, the underside of the tread being in load-bearing engagement with the rung,the tread being assembled to the ladder as a wedgefitorsnapfit.

By these means, no separate attachment is necessarythus producing considerable savings in material and labour in manufacture.

In a particular cheap construction, the styles and rungs are made of steel tube, with the rung simply fixed to the styles at each end by rivets or the like.

The tread is preferably of substantial width, that is to say a multiple ofthe width ofthe rung so as to provide an ample supporting surface for the foot of the user.

This means that the plastics material is cantilevered on opposite sides of the rung, but ample rigidity can be provided by appropriate design as will be more particularly explained with reference to the accompanying drawings wherein :- Figure lisa fragmentary perspective view of a single tread; Figure 2 is a fragmentary side elevation of a ladder; and Figure 3 is an enlarged sectional elevation on the line 3-3, Figure 1.

Referring now to the drawings, the ladder seen in Figure 2 comprises a pair of stiles 1 which may be made ofsteeltube. Aseries of rungs 12,14 may be made ofsimilartube extending between the stiles, and their ends may be shaped and welded to the stiles 10, orfor simplicity their ends may be flattened, part wrapped around the stiles, and rivetted or heid in place by screws for example.

The tread 16 is a one-piece plastics injection moulding comprising a main flat area 20 to provide the tread proper and end parts 22, 24 forengagement with the stiles.

The central part20 may be provided with ribs or grooves 26 or other patterns to provide a non-slip surface.

Each end 22 or 24 has a deep groove 28 of suitable cross-section to accommodate the style 10. The groove extends generally diagonaily across each end face so thatfor example as seen in Figure 2 when the ladder is in an inclined position for use, the surface 20 extends generally horizontally.

The illustrated tread is not to be assumed to be a solid body, in fact it is of honeycomb like shape, or in other words comprises an external wall 30 as seen in Figure 3 reinforced by a series of parallel webs such as 32 extending transversely, or extending in other directions. All of these walls and surfaces may be of substantiallythe same thickness of plastics material.

However, instead of using webs, the underside of the tread may be provided with a series of frustopyramidal recesses.

A groove is formed lengthwise of the tread on the underside, to receive the rung therein.

Preferably the tread has a slight degree of flexibility.

This isforthe purpose of providing simple assembly of the tread to the rung.

Itwill beobservedfrom consideration of Figures 1 and 2 that, if the stiles and rungs are fixed together before the treads are assembled, itwill be impossible to locate a tread in a desired position above a rung and simply move it th rough a series of positions in which it remained parallel to the rung until it was fully engaged. This might be possible in the case of a top rung and on the assumption thatthe stiles were not fixed to any structure at their upper ends, in other words by effectively "threading" the stiles along the length ofthe grooves 28.Although such a technique could be used to assemble a ladder, placing one rung and tread in position before the next, and son on, this is considered to be unsatifactoryand unsuitable.

However, a design according to the present invention can cope with this difficulty.

Particularly by providing the slightflexibilty as mentioned, it can be possible to locate a tread in a positionforexample between the rungs 12 and 14 extending generally diagonally, in otherwords so that one end of the tread is adjacent one end of rung 12 and the opposite end of the same tread is adjacent the opposite end (that is the end next to the other stile) of rung 14. One end of the groove 28 adjacent rung 12 is fully registered and aligned with the stile of that side, and the opposite end ofthe groove of the opposite end of the tread is brought into register and alignment with the stile at its end.The tread is then moved from the diagonally extending or including position towards the position in which it is parallel to the rung and in which the rung enters the groove 42 and this is accompanied by deformation and subsequent return to the undeformed condition of the tread. When so located the tread is quite secure without any addition al fastening being required.

1. A ladder comprising two stiles, a rung extending therebetween and a tread located adjacentthe rung, characterised in that the tread comprises a plastics moulding having aligned recesses at respective ends to receive the respective stiles in engagement therein, the underside of the tread being in load-bearing engagement with the rung, the tread being assembled to the ladder as a wedge fit or snap fit.

2. A ladder as claimed in Claim 1 wherein the tread comprises a generally flat area having a width which is a multiple of the width ofthe rung of the ladder, and a pair of upstanding end portions each provided with one of said recesses therein.

3. A ladder as claimed in Claim 1 wherein said recesses are inclined at an angle such that when the ladder is in its intended position of use, the upper surface ofthetread is substantiaily horizontal.

4. Aladderaccordingtoanyofclaimsl to3 wherein thetread is an injection moulding comprising an external wall and a honeycomb or like reinforcement containedwithin and below said wall.

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

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Ladder This invention relates to ladders, including within its scope such similarconstructions as steps, step stools and the like. According to the invention a ladder comprises two stiles, a rung extending therebetween, and a tread located adjacent the rung, characterised in that the tread comprises a plastics moulding having aligned recesses at respective ends to receive the respective stiles in engagement therein, the underside of the tread being in load-bearing engagement with the rung,the tread being assembled to the ladder as a wedgefitorsnapfit. By these means, no separate attachment is necessarythus producing considerable savings in material and labour in manufacture. In a particular cheap construction, the styles and rungs are made of steel tube, with the rung simply fixed to the styles at each end by rivets or the like. The tread is preferably of substantial width, that is to say a multiple ofthe width ofthe rung so as to provide an ample supporting surface for the foot of the user. This means that the plastics material is cantilevered on opposite sides of the rung, but ample rigidity can be provided by appropriate design as will be more particularly explained with reference to the accompanying drawings wherein :- Figure lisa fragmentary perspective view of a single tread; Figure 2 is a fragmentary side elevation of a ladder; and Figure 3 is an enlarged sectional elevation on the line 3-3, Figure 1. Referring now to the drawings, the ladder seen in Figure 2 comprises a pair of stiles 1 which may be made ofsteeltube. Aseries of rungs 12,14 may be made ofsimilartube extending between the stiles, and their ends may be shaped and welded to the stiles 10, orfor simplicity their ends may be flattened, part wrapped around the stiles, and rivetted or heid in place by screws for example. The tread 16 is a one-piece plastics injection moulding comprising a main flat area 20 to provide the tread proper and end parts 22, 24 forengagement with the stiles. The central part20 may be provided with ribs or grooves 26 or other patterns to provide a non-slip surface. Each end 22 or 24 has a deep groove 28 of suitable cross-section to accommodate the style 10. The groove extends generally diagonaily across each end face so thatfor example as seen in Figure 2 when the ladder is in an inclined position for use, the surface 20 extends generally horizontally. The illustrated tread is not to be assumed to be a solid body, in fact it is of honeycomb like shape, or in other words comprises an external wall 30 as seen in Figure 3 reinforced by a series of parallel webs such as 32 extending transversely, or extending in other directions. All of these walls and surfaces may be of substantiallythe same thickness of plastics material. However, instead of using webs, the underside of the tread may be provided with a series of frustopyramidal recesses. A groove is formed lengthwise of the tread on the underside, to receive the rung therein. Preferably the tread has a slight degree of flexibility. This isforthe purpose of providing simple assembly of the tread to the rung. Itwill beobservedfrom consideration of Figures 1 and 2 that, if the stiles and rungs are fixed together before the treads are assembled, itwill be impossible to locate a tread in a desired position above a rung and simply move it th rough a series of positions in which it remained parallel to the rung until it was fully engaged. This might be possible in the case of a top rung and on the assumption thatthe stiles were not fixed to any structure at their upper ends, in other words by effectively "threading" the stiles along the length ofthe grooves 28.Although such a technique could be used to assemble a ladder, placing one rung and tread in position before the next, and son on, this is considered to be unsatifactoryand unsuitable. However, a design according to the present invention can cope with this difficulty. Particularly by providing the slightflexibilty as mentioned, it can be possible to locate a tread in a positionforexample between the rungs 12 and 14 extending generally diagonally, in otherwords so that one end of the tread is adjacent one end of rung 12 and the opposite end of the same tread is adjacent the opposite end (that is the end next to the other stile) of rung 14. One end of the groove 28 adjacent rung 12 is fully registered and aligned with the stile of that side, and the opposite end ofthe groove of the opposite end of the tread is brought into register and alignment with the stile at its end.The tread is then moved from the diagonally extending or including position towards the position in which it is parallel to the rung and in which the rung enters the groove 42 and this is accompanied by deformation and subsequent return to the undeformed condition of the tread. When so located the tread is quite secure without any addition al fastening being required. CLAIMS

1. A ladder comprising two stiles, a rung extending therebetween and a tread located adjacentthe rung, characterised in that the tread comprises a plastics moulding having aligned recesses at respective ends to receive the respective stiles in engagement therein, the underside of the tread being in load-bearing engagement with the rung, the tread being assembled to the ladder as a wedge fit or snap fit.

2. A ladder as claimed in Claim 1 wherein the tread comprises a generally flat area having a width which is a multiple of the width ofthe rung of the ladder, and a pair of upstanding end portions each provided with one of said recesses therein.

3. A ladder as claimed in Claim 1 wherein said recesses are inclined at an angle such that when the ladder is in its intended position of use, the upper surface ofthetread is substantiaily horizontal.

4. Aladderaccordingtoanyofclaimsl to3 wherein thetread is an injection moulding comprising an external wall and a honeycomb or like reinforcement containedwithin and below said wall.

5. A ladder as claimed in any preceding claim wherein a recess is provided along the underside of the tread to receive the rung in engagementtherein.

6. A ladder substantially as described with refer encetotheaccompanying drawings.