Ladder

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A ladder is a vertical or inclined set of rungs or steps. There are two types: rigid ladders that can be leaned against a vertical surface such as a wall, and rope ladders that are hung from the top. The vertical members of a rigid ladder are called stringers (US) or stiles (UK). Rigid ladders are usually portable, but some types are permanently fixed to buildings. They are commonly made of metal or fiberglass, but they have been known to be made of tough plastic.

Contents

Variations

Rigid ladders are available in many forms, such as:

  • Bridge ladder, a ladder laid horizontally to act as passage between two points separated by a drop.
  • Cat ladder (US chicken ladder), a lightweight ladder frame used on steep roofs to prevent workers from sliding
  • Extension ladder or "Telescopic ladder", a fixed ladder divided into two or more lengths for more convenient storage; the lengths can be slid together for storage or slid apart to maximize the length of the ladder; a pulley system may be fitted so that the ladder can be easily extended by an operator on the ground then locked in place using the dogs and pawls
  • Fixed ladder, two side members joined by several rungs; affixed to structure with no moving parts
  • Folding ladder, a ladder in the step ladder style with one or more (usually no more than three) one-way hinges. Ideal for use on uneven ground (i.e. stairs), as a trestle or when fully extended a Fixed ladder. Some variations feature a central one-way hinge with extensible locking legs
  • Hook ladder or pompier ladder, a rigid ladder with a hook at the top to grip a windowsill; used by firefighters
  • Orchard ladder, a three legged step ladder with third leg made so that it can be inserted between tree branches for fruit picking
  • Platform steps, a step ladder with small horizontal platform at the top
  • Roof ladder, a rigid ladder with large hook at the top to grip the ridge of a pitched roof
  • Step ladder, hinged in the middle to form an inverted V, with stays to keep the two halves at a fixed angle
  • Turntable ladder, an extension ladder fitted to rotating platform on top of a fire truck
  • Vertically rising ladder, a ladder designed to climb high points and facilitate suspending there.

Rigid ladders were originally made of wood,but in the 20th century tubular aluminium became more common because of its lighter weight. Ladders with fibreglass stiles are used for working on or near overhead electrical wires, because fibreglass is an electrical insulator.[1]

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