butterfly door

English

1996 McLaren F1 with butterfly doors.

butterfly door on coal-fueled steam-engine firebox

Two center-pivoting butterfly doors; (R-to-L) one fully open, one fully closed

simple schematic diagram of center-pivoting butterfly door

Noun

butterfly door (plural butterfly doors)

1. (automotive) A car door similar to scissor door, but while scissor doors move straight up via hinge points at the bottom of the A-pillar, butterfly doors move up and out via hinges along the A-pillar.
2. (of stationary or locomotive boilers) A door consisting of two leaves that swing on a pivot above the center of the firebox opening to open and close.
   • 1953 February, “British Railways Standard Class "4" 2-6-0 Locomotives”, in Railway Magazine, page 108:

     The two-hopper, self-emptying ashpan has butterfly doors operated by a hand lever from ground level, and its damper doors, fore and aft, are controlled separately by standard hand wheels and screw gear.

3. (architecture) A door which pivots on a central axis, used in locations with a pressure differential between the two sides of the door, so that forces exhibited do not inhibit opening and closing of the door, due to contrary action of forces on the two halves of the door which open inwards and outwards at the same time.

Translations

type of car door

• Finnish: perhosovi
• French: porte papillon (fr) f
• German: Schmetterlingstür f
• Italian: portiera ad ala di gabbiano

type of boiler door

architecture: type of door

• Finnish: pyöröovi (fi)

See also

• butterfly valve

Further reading

• Butterfly doors on Wikipedia.Wikipedia (automotive)
• Category:Automobiles with butterfly doors on Wikimedia Commons.Wikimedia Commons
• Firebox (steam engine) on Wikipedia.Wikipedia
• Category:Butterfly doors (architectural) on Wikimedia Commons.Wikimedia Commons