GB2251262A - Improvements in ladders - Google Patents

Abstract

A ladder comprises tubular steel stiles 10, 12, and tubular steel rungs 14 which are fixed to the stiles for example by having flattened ends welded to the stiles. A plastics step 18 has grooves at each end to receive the stiles and is snap- engaged in position with spigots 22 entering apertures in the stiles to locate the tread axially along the length of the stiles and prevent dis-engagement. Alternatively the spigots may be replaced by a bolted connection and the steel rungs 14 may be omitted if the step is strong and rigid (Figure 4 not shown). <IMAGE>

Description

IMPROVEMENTS IN LADDERS This invention relates to ladders and the like, and is particularly concerned it relatively short flights of steps as used or example for internal domestic purposes, or as part of children's exercise equipment or example slides. A relative lightweight construction is suitable for these purposes, and cost is an important factor for econonic viability. For this reason assemblies of steel tubes typically of the order of 25mm diameter are often used for both stiles and sometimes also runs, the parts being welded together or example using flattened ends of the tubular rungs part wrapped about te stiles.These are unsatisfactory for small children because of the possibility o feet slipping on the circular cross-section runs. So it has been usual to rivet or weld on a netal pressing to make a wide flat tread. This complicates construction and increases weight and costs.

In an attempt to simplify and reduce cost and weight, plastics steps have een used with the rungs.

However, the usual Flexibility of plastics has been considered a disadvantage since the plastics parts could not easily be fixed to the rungs by the riveting or weldin step.

Our prior Patent GB 2 185 775 discloses a ladder made of stiles and rungs, with a separate tread comprising a plastics moulding assembled to each run.

or these purposes the moulding as aligned recesses at each end to receive te respective stiles which engage in those recesses, and has a deep groove on its underside to receive the rungs. The tread has been made stroner by a honeycomb construction.The preferred assembly method as described in said natent is to locate the tread in the space between the stiles and locate it diagonally between a pair of rungs, resister the stile of one side with the recess. and trzen nove te tread towards a position parallel with the rungs. is is accompanied Dy deformation and subsequent return to the undeformed state of the tread.

Although the ladders of said prior patent have been successful commercially, it is found that even with the honeycomb construction, the necessary flexibility and clearances needed result in the eventual possibility o looseness and play developing in which the assembly method could be reversed to allow or cause removal of the tread. The easier it is to assemble the treads in a factory when the ladder is being made, the more likely it is that the treads will subsequently become detached.

The object of the invention is to provide improvements.

According to the invention a ladder comprises a pair of stiles and a plurality of steps extending rung-wise between the stiles, each step comprising a plastics moulding of substantial width to provide a tread, and having integral vertically extending parallel face portions of substantial length at each end adjacent t stiles, said portions being normal to te tread and grooved to receive and accommodate the stiles in the grooves, and each said face being provided with means or locating the race relative to the length of the stiles.

S:y these means the step ay be assembled in generally the same way as in said prior patent, t the location means may snap-engage (for example) and in any event prevent the reverse action and removal and detachment.

The said face may have a length which is for example of the sae order as the tread width. The substantial length of the complementary faces of the stiles and grooves distributes torsional load and prevents lozenging.

It has now been discovered experimentally that the plastics sten o.v be so strong and rig i t at the usual run can dne dispensed with. In tis event it is preferred to use a nut and bolt as the location means, and to hold the parts together.

According to an aspect of the invention, the ladder is made rungless.

Two embodiments of the invention are no described with reference to the accompanying drawings wherein: Figure 1 is a sectional elevation of a fragment of a ladder; Figure 2 is a plan view of a step therefor; Figure 3 is a side elevation of Figure 1; and Figures 4-6 are similar vies tat show the second embodiment.

Turning first to Figures 1 to 3, the ladder here comprises stiles 10, 12 fixed to rungs 14. They may all be metal tubes bolted or welded together, typically with flattened ends of the rungs wrapping the stiles. The steps 16 are plastics mouldings of substantial width W to provide a tread, and of substantial length L at each end 20 of tlie tread, where te steps are grooved at 22 to accommodate the stiles. The latter are apertured on adjacent faces and the said ends have projecting spigots 22 or snap-engagement in those apertures.

As seen in Figure 3, the step is of inverted channel section to embrace the rung and be located thereby, anci this inter-engagement of the grooves and channel with the stiles and rung respectively is sufficient to retain the step in te ladder, and the step provides a but tress or reinforcement against lozenging due particularly to the length L. In fact the step rigidifies the construction and enables a 1 ightweight construction to be use for stile and rungs. Additionally, suc a ladder may be particularly economical to manufacture especially in assembly. Tie steps nay be snap-engaged with the assembled rungs and stiles due to the nature of the plastic material.

In Figures 4-6 the rungs are omitted and bolts 39 and nuts 40 hold the steps to the stiles so as to provide the rigidified structure. It will be appreciated that the steps used in the Figures 4-6 construction must possess greater strength than is required in Figures 1-3.

Figure 3 shows an arrangement in which te tread face 37 is horizontal when the stiles 10, 12 are at a predetermined angle to th ground. Figure 6 shows an arrangement in which the ladder is to extend vertically and hence the tread face 37 is horizontal.

Claims (6)

1. A ladder comprising a pair of stiles and a plurality of steps extending rung-wise between the stiles, each step comprising a plastics moulding of substantial width to provide a tread, and having integral vertically extending parallel face portions of substantial length at eaci end adjacent the stiles, said portions being normal to the tread and grooved to receive and accommodate the stiles in the grooves, and each said face being provided with means for locating the face relative to the length of the stiles.

2. ladder as claimed in Claim 1 wherein the stiles are apertured on adjacent faces, and the said parallel face portions of the steps have projecting spigots which engage in said apertures for said location.

3. A ladder as claimed in Claim 1 or Claim 2 wherein the ladder comprises stiles and rungs and each step is of inverted channel section and embraces a corresponding rung.

4. A ladder as claimed in Claim 1 wherein the stiles ann rungs are apertured and bolts extend through said apertures to provide said location means.

5. A rung less ladder as claie in Claim 4.

6. A ladder substantially as described with reference to Figures 1-3 or 4-6 of the accompanying drawings.

6. A ladder substantially as described with reference to Figures 1-3 or 4-6 of the accompanying drawings.

Amendments to the claims have been filed as follows 1. A ladder comprising a pair of stiles and a plurality of steps extending rung-wise between the stiles, each step comprising a plastics moulding of substantial width to provide a tread, and having integral vertically extending oppositely directed parallel face portions of substantial length at each end adjacent the stiles, said portions being normal to the tread and grooved to receive and accommodate the stiles in the grooves, and each said face being provided with means for locating the face relative to the length of the stiles.

2. A ladder as claimed in Claim 1 wherein the stiles are apertured on adjacent faces, and the said parallel face portions of the steps have projecting spigots which engage in said apertures for said location.

3. A ladder as claimed in Claim 1 or Claim 2 wherein the ladder comprises stiles and rungs and each step is of inverted channel section and embraces a corresponding rung.

4. A ladder as claimed in Claim 1 wherein the stiles and rungs are apertured and bolts extend through said apertures to provide said location means.

5. A rungless ladder as claimed in Claim 4.