A ladder is a vertical or inclined set of rungs or steps commonly used for climbing or descending. There are two types: rigid ladders that are self-supporting or that may be leaned against a vertical surface such as a wall, and rollable ladders, such as those made of rope or aluminium, that may be hung from the top. The vertical members of a rigid ladder are called stringers or rails (US) or stiles (UK). Rigid ladders are usually portable, but some types are permanently fixed to a structure, building, or equipment. They are commonly made of metal, wood, or fiberglass, but they have been known to be made of tough plastic.
Ladders are ancient tools and technology. A ladder is featured in a Mesolithic rock painting that is at least 10,000 years old, depicted in the Spider Caves in Valencia, Spain. The painting depicts two humans using a ladder to reach a wild honeybee nest to harvest honey. The ladder is depicted as long and flexible, possibly made out of some sort of grass. [1]
Rigid ladders are available in many forms, such as:
Rigid ladders were originally made of wood, but in the 20th century aluminium became more common because of its lighter weight. Ladders with fiberglass stiles are used for working on or near overhead electrical wires, because fiberglass is an electrical insulator. [5] Henry Quackenbush patented the extension ladder in 1867. [6]
The most common injury made by ladder climbers is bruising from falling off a ladder, but bone fractures are common and head injuries are also likely, depending on the nature of the accident. Ladders can cause injury if they slip on the ground and fall. To avoid this, they tend to have plastic feet or base pads which increase friction with the ground. However, if the plastic is badly worn, the aluminium may contact the ground increasing the chance of an accident. Ladder stabilizers are also available to increase the ladder's grip on the ground. One of the first ladder stabilizers or ladder feet was offered in 1936 and today they are standard equipment on most large ladders. [8]
A ladder standoff, or stay, is a device fitted to the top of a ladder to hold it away from the wall. This enables the ladder to clear overhanging obstacles, such as the eaves of a roof, and increases the safe working height for a given length of ladder because of the increased separation distance of the two contact points at the top of the ladder.
It has become increasingly common to provide anchor points on buildings to which the top rung of an extension ladder can be attached, especially for activities like window cleaning, especially if a fellow worker is not available for "footing" the ladder. Footing occurs when another worker stands on the lowest rung and so provides much greater stability to the ladder when being used. However footing a ladder should be seen as a last resort for a safe placement. [9] The anchor point is usually a ring cemented into a slot in the brick wall to which the rungs of a ladder can be attached using rope for example, or a carabiner.
If a leaning ladder is placed at the wrong angle, the risk of a fall is greatly increased. The safest angle for a ladder is 75.5°; if it is too shallow, the bottom of the ladder is at risk of sliding, and if it is too steep, the ladder may fall backwards. This angle is achieved by following the 4 to 1 rule for a ladder placed on a vertical wall: for every four feet of vertical height, the ladder foot should move one foot from the wall. Both scenarios can cause significant injury, and are especially important in industries like construction, which require heavy use of ladders. [10]
The European Union and the United Kingdom established a ladder certification system – ladder classes – for any ladders manufactured or sold in Europe. The certification classes apply solely to ladders that are portable such as stepladders and extension ladders and are broken down into three types of certification. Each ladder certification is colour-coded to indicate the amount of weight the ladder is designed to hold, the certification class and its use. The color of the safety label specifies the class and use.
A common superstition in English-speaking countries is that walking under a ladder is seen as bad luck. Some sources claim that this stems from the image of a ladder being propped up against a wall looking similar to a gallows, [12] while others attribute it to ancient Egyptian traditions involving pyramids and triangles representing the trinity of the gods, and passing through the triangular shape made by a ladder against a wall was seen as desecration. Ladders have also been linked to the crucifixion of Christ, with author and scientist Charles Panati noting that many believe a ladder rested against the cross that Christ hung from, making it a symbol of wickedness, betrayal and death. [13] In comedic children's media, the image of a character walking under a ladder being the cause or result of bad luck has become a common trope. [14] [15]
Scrambling is a mountaineering term for ascending steep terrain using one's hands to assist in holds and balance. "A scramble" is a related term, denoting terrain that could be ascended in this way. It can be described as being between hiking and rock climbing.
Scaffolding, also called scaffold or staging, is a temporary structure used to support a work crew and materials to aid in the construction, maintenance and repair of buildings, bridges and all other human-made structures. Scaffolds are widely used on site to get access to heights and areas that would be otherwise hard to get to. Unsafe scaffolding has the potential to result in death or serious injury. Scaffolding is also used in adapted forms for formwork and shoring, grandstand seating, concert stages, access/viewing towers, exhibition stands, ski ramps, half pipes and art projects.
A fish ladder, also known as a fishway, fish pass, fish steps, or fish cannon, is a structure on or around artificial and natural barriers to facilitate diadromous fishes' natural migration as well as movements of potamodromous species. Most fishways enable fish to pass around the barriers by swimming and leaping up a series of relatively low steps into the waters on the other side. The velocity of water falling over the steps has to be great enough to attract the fish to the ladder, but it cannot be so great that it washes fish back downstream or exhausts them to the point of inability to continue their journey upriver.
Glossary of climbing terms relates to rock climbing, mountaineering, and to ice climbing.
Rock-climbing equipment varies with the specific type of climbing that is undertaken. Bouldering needs the least equipment outside of climbing shoes, climbing chalk and optional crash pads. Sport climbing adds ropes, harnesses, belay devices, and quickdraws to clip into pre-drilled bolts. Traditional climbing adds the need to carry a "rack" of temporary passive and active protection devices. Multi-pitch climbing, and the related big wall climbing, adds devices to assist in ascending and descending fixed ropes. Finally, aid climbing uses unique equipment to give mechanical assistance to the climber in their upward movement.
A truss is an assembly of members such as beams, connected by nodes, that creates a rigid structure.
A swing is a seat or platform, suspended from chains, ropes, or bars, on which one or more people can swing back and forth for enjoyment or relaxation. Swings are a common piece of equipment at children's playgrounds and may also be found in yards or gardens, on porches, inside homes, or as freestanding public play equipment like the Estonian village swing. Swings have a long history in many different parts of the world and come in various types.
Aid climbing is a form of rock climbing that uses mechanical devices and equipment, such as aiders, for upward momentum. Aid climbing is contrasted with free climbing, which only uses mechanical equipment for protection, but not to assist in upward momentum. Aid climbing can involve hammering in permanent pitons and bolts, into which the aiders are clipped, but there is also 'clean aid climbing' which avoids any hammering, and only uses removable placements.
A dive boat is a boat that recreational divers or professional scuba divers use to reach a dive site which they could not conveniently reach by swimming from the shore. Dive boats may be propelled by wind or muscle power, but are usually powered by internal combustion engines. Some features, like convenient access from the water, are common to all dive boats, while others depend on the specific application or region where they are used. The vessel may be extensively modified to make it fit for purpose, or may be used without much adaptation if it is already usable.
A fire escape is a special kind of emergency exit, usually mounted to the outside of a building—occasionally inside, but separate from the main areas of the building. It provides a method of escape in the event of a fire or other emergency that makes the stairwells inside a building inaccessible. Fire escapes are most often found on multiple-story residential buildings, such as apartment buildings.
This is a glossary of firefighting equipment.
An assault course is a trail that combines running and exercising. It is often used in military training. The prime use is to evaluate progress and weaknesses of the individual or the team involved.
The term Jacob's ladder, used on a ship, applies to two kinds of rope ladders. The term may also appear without the apostrophe, as Jacobs ladder.
A fly system, or theatrical rigging system, is a system of ropes, pulleys, counterweights and related devices within a theater that enables a stage crew to fly (hoist) quickly, quietly and safely components such as curtains, lights, scenery, stage effects and, sometimes, people. Systems are typically designed to fly components between clear view of the audience and out of view, into the large space, the fly loft, above the stage.
Exercise equipment is any apparatus or device used during physical activity to enhance the strength or conditioning effects of that exercise by providing either fixed or adjustable amounts of resistance, or to otherwise enhance the experience or outcome of an exercise routine.
Window cleaning, or window washing, is the exterior cleaning of architectural glass used for structural, lighting, or decorative purposes. It can be done manually, using a variety of tools for cleaning and access. Technology is also employed and increasingly, automation.
Grab bars are safety devices designed to enable a person to maintain balance, lessen fatigue while standing, hold some of their weight while maneuvering, or have something to grab onto in case of a slip or fall. A caregiver may use a grab bar to assist with transferring a patient from one place to another. A worker may use a grab bar to hold on to as he or she climbs, or in case of a fall.
Tree stands or deer stands are open or enclosed platforms used by hunters. The platforms are secured to trees in order to elevate the hunter and give them a better vantage point. A tripod stand is a similar device, but because it is freestanding rather than attached to a tree, it is not technically a tree stand.
Caving equipment is equipment used by cavers and speleologists to aid and protect them while exploring caves. The term may also be used to refer to equipment used to document caves, such as photographic and surveying equipment. Originally, cave diving equipment was quite limited, but the increasing popularity of caving during the 20th century led to the creation of specialist caving equipment and companies.
Step stools are halfway between a ladder and a stool, being used, as a support platform, for reaching targets that are at heights between ~2m and ~3m. The most common modern type is made with two separate ladders connected to each other at the upper end, where there is a platform with an area big enough to stand with both feet on it, having the rest of steps the same area, but not in all models, for some step stools have classical ladder steps. This folding design arrangement eliminates the need for a fixed support on a wall, as in the case of a standard ladder. They are widely used in the kitchen, to the point that in some places they are called "kitchen ladder".
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