Trapdoor
Encyclopedia
Originally, trapdoors were sack traps in mills, and allowed the sacks to pass up through the mill while naturally falling back to a closed position.
An exposed trapdoor is often called a hatch
Hatch
Hatch may refer to:* Hatching, also called "cross-hatching", an artistic technique used to create tonal or shading effects using closely spaced parallel lines* Hatching, the emergence of a young animal from an egg...
, although hatches may be horizontal. Many buildings with flat roof
Roof
A roof is the covering on the uppermost part of a building. A roof protects the building and its contents from the effects of weather. Structures that require roofs range from a letter box to a cathedral or stadium, dwellings being the most numerous....
s have hatches that provide access to the roof; on ship
Ship
Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...
s, hatches—never called trapdoors—provide access to the deck
Deck (ship)
A deck is a permanent covering over a compartment or a hull of a ship. On a boat or ship, the primary deck is the horizontal structure which forms the 'roof' for the hull, which both strengthens the hull and serves as the primary working surface...
. Cargo ship
Cargo ship
A cargo ship or freighter is any sort of ship or vessel that carries cargo, goods, and materials from one port to another. Thousands of cargo carriers ply the world's seas and oceans each year; they handle the bulk of international trade...
s, including bulk carrier
Bulk carrier
A bulk carrier, bulk freighter, or bulker is a merchant ship specially designed to transport unpackaged bulk cargo, such as grains, coal, ore, and cement in its cargo holds. Since the first specialized bulk carrier was built in 1852, economic forces have fueled the development of these ships,...
s, have large hatches for access to the hold
Hold (ship)
thumb|right|120px|View of the hold of a container shipA ship's hold is a space for carrying cargo. Cargo in holds may be either packaged in crates, bales, etc., or unpackaged . Access to holds is by a large hatch at the top...
s. A small door in a wall, floor or ceiling used to gain access to equipment is called an access hatch. Hidden trapdoors occasionally appear in fiction, either as entrances to secret passage
Secret passage
Secret passages, also commonly referred to as hidden passages or secret tunnels, are hidden routes used for stealthy travel. Such passageways are sometimes inside buildings leading to secret rooms. Others allow occupants to enter or exit buildings without being seen...
ways, or as literal traps into which a helpless pedestrian may fall if he or she happens to stand on one.
Most 19th- and 20th Century gallows
Gallows
A gallows is a frame, typically wooden, used for execution by hanging, or by means to torture before execution, as was used when being hanged, drawn and quartered...
featured a trapdoor, usually with two flaps. The victim was placed at the join. The edge of a trapdoor farthest from the hinge accelerates faster than gravity, so that the victim does not hit the flaps but falls freely.
The term trapdoor also refers to a plate in the vestibule of a railcar
Railcar
A railcar, in British English and Australian English, is a self-propelled railway vehicle designed to transport passengers. The term "railcar" is usually used in reference to a train consisting of a single coach , with a driver's cab at one or both ends. Some railways, e.g., the Great Western...
that permits access to high-level platforms when lying flat against the floor of the car and can be flipped open to expose steps for accessing ground-level platforms. Many American commuter railroads who operate the Comet railcars made by Bombardier
Bombardier Transportation
Bombardier Transportation is the rail equipment division of the Canadian firm, Bombardier Inc. Bombardier Transportation is one of the world's largest companies in the rail-equipment manufacturing and servicing industry. Its headquarters are in Berlin, Germany....
have trap doors to accommodate loading and unloading of passengers on both high-level and ground-level platforms. Amtrak
Amtrak
The National Railroad Passenger Corporation, doing business as Amtrak , is a government-owned corporation that was organized on May 1, 1971, to provide intercity passenger train service in the United States. "Amtrak" is a portmanteau of the words "America" and "track". It is headquartered at Union...
's Viewliner
Viewliner
The Viewliner is a single-level car type used by Amtrak on eastern routes. With the exception of a prototype dining car named "Indianapolis" , all cars built so far are sleeping cars and are assigned names that include the word "View."- Early design :...
, Amfleet
Amfleet
Amfleet is a series of intercity railroad passenger cars built for the operator Amtrak by the manufacturer Budd Company in two series during the late 1970s and early 1980s. Today, Amfleet cars are used extensively throughout the Amtrak system outside the western United States...
, and Horizon
Horizon
The horizon is the apparent line that separates earth from sky, the line that divides all visible directions into two categories: those that intersect the Earth's surface, and those that do not. At many locations, the true horizon is obscured by trees, buildings, mountains, etc., and the resulting...
railcar fleets all have trapdoors.
Trapdoor spider
Trapdoor spider
Trapdoor spiders are medium-sized mygalomorph spiders that construct burrows with a cork-like trapdoor made of soil, vegetation and silk. Some similar species are also called trapdoor spiders, such as the Liphistiidae, Barychelidae, Cyrtaucheniidae and some Idiopidae and Nemesiidae...
s dig out an underground nest they line with their silk, and then top it with a hinged lid, the trapdoor.