Drop-down ladders specification guide
1. Materials
- Only materials not subject to corrosion can be used. The ladder is made of aluminum alloy profiles, anodized 10 micron, natural mat finishing; fasteners (bolts, rivets and washers) of stainless steel A2-70 DaN/mm2; joint washers, bushes, plugs, etc. in polyamide and elastomer.
- No protective treatment, painting or maintenance is required, except when exposed to aggressive environments.
- No welding is allowed. The rungs are clinched into the uprights. Bolts and rivets are used for all other assembly.
- The ladder can be polyester powder coated in any RAL color (option).
2. Installation
- Counterbalanced ladders are installed vertically.
- A single type of fixing clamps is used for the attachments of wall fasteners and safety cage hoops to the ladder uprights. These fixing clamps can be clipped to the ladder uprights at any desired position.
- In order to take into account the different thermal expansion of the wall structure and the ladder, the ladder can expand freely within its anchor brackets without deformation or damage.
- For lateral access to the ladder, the upper rung will be at approximately 5 ft or 1.5 m above the upper point of access. For access from the top, widened upright projections, allowing a passageway of at least 2’4” or 62 cm, can be used. In the latter case the upper rung is at level with the access floor.
3. Dimensions
- The ladder corresponds to standards EN 131 and ISO 14122-4.
- The ladder is composed of standardized elements of 11 ft or 3.36 m maximal length, which are assembled to the desired length. These elements are connected by perforated aluminum sleeves that are shifted inside the uprights. Bolts are used for fastening.
- The uprights are spaced at 1’4” or 400 mm, the rung axes at 11” or 280 mm.
- The ladder uprights have an oblong section (2-15/16” x 1” x 5/64” or 75 x 25 x 2 mm) with rounded corners. The rungs are round (Ø 1-1/2” or 33 mm) with a flattened and grooved anti-slip upper face.
4. Counterbalanced Lower Sliding Ladder
- A counterbalanced lower sliding ladder can be provided to prevent access by unauthorized persons:
- clearance height, i.e. the distance between the floor and the foot of the sliding ladder is maximum 9’10” or 3 m;
- the sliding part is counterbalanced by weights that shift in hollow profiles;
- axes, springs and cables are of stainless steel, pulley wheels of polyacetal (POM-H);
- release of the sliding part is possible via a mechanism controlled from above, from below or from the side (to be specified). Release via a foot treadle is possible.