Stepladders, extension ladders, aerial ladders, roof ladders and combination ladders are some of the different types of ladders firefighters use to do their job. Regardless of the type, ladders are intended to do one thing: extend a firefighter's reach. Even though many types of ladders may be used, many of their parts are the same. The 24-foot extension ladder is the standard ladder found on most pumpers.
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Beam and Rungs
The side rails of a ladder are called beams. They provide the basic structure and support of the ladder. The beams are constructed of wood, aluminium or fibreglass. For a standard two section ladder, the beam may be 4 inches wide, but this depends on the material used and the manufacturer. The rungs are the horizontal cross members that connect the beams and where the feet are placed for climbing. Rungs must be a minimum of 1 1/4 inches in diameter.
Base and Fly
There are two principle parts to any extension ladder: the base and the fly. The base or bed is the bottom section. The base is wider, more heavily constructed and it holds the fly section of the ladder.
The fly is the smaller upper section of the ladder. It is the part that extends or is raised to give the ladder its height. All other parts attach to either of these sections.
Pulley and Halyard
The pulley and halyard, or rope, are used to raise the fly section of the ladder. The pulley is attached to an upper rang on the fly and the halyard is attached to a lower rang on the fly. To raise the fly section, a person stands behind the ladder, pulls the rope downward and the fly goes up. This is usually a two person task.
Stops and Pawls
Stops are made of steel, and a set is applied to each section of the ladder at predetermined points. The stops prevent the fly from being raised too high and compromising the strength of the extended ladder. Pawls, or dogs, are the structured metal pieces attached to the inside of the beams on the fly section. When the fly is raised, the pawls fit over the rungs of the base to secure it in place.
The hooks are large spring-loaded devices that are located at the tip of each beam. The spring mechanism allows for the hooks to be locked into place in either their storage or deployed position. These hooks, when deployed, can secure the ladder over the peak of a roof or in a window opening giving a firefighter one more tool in a dangerous situation.
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- National Fire Protection Association, 1931, Standard for Manufacturer's Design of Fire Brigade Ground Ladders, Chapter 3
- National Fire Protection Association, 1932, Standard on Use, Maintenance, and Service Testing of Fire Brigade Ground Ladders
- Occupational Safety and Health Administration, 29 CFR 1910.26, Standard for Portable metal Ladders