Category:Expansion

Ex*pan"sion, n. Etym: [L. expansio: cf. F. expansion.]

1. The act of expanding or spreading out; the condition of being expanded; dilation; enlargement.

2. That which is expanded; expanse; extend surface; as the expansion of a sheet or of a lake; the expansion was formed of metal. The starred expansion of the skies. Beattie.

3. Space thought which anything is expanded; also, pure space. Lost in expansion, void and infinite. Blackmore.

4. (Com.)

Defn: Enlargement or extension of business transaction; esp., increase of the circulation of bank notes.

5. (Math.)

Defn: The developed result of an indicated operation; as, the expansion of (a + b)2 is a2 + 2ab + b2.

6. (Steam Ebgine)

Defn: The operation of steam in a cylinder after its communication with the boiler has been cut off, by which it continues to exert pressure upon the moving piston.

7. (Nav. Arch.)

Defn: The enlargement of the ship mathematically from a model or drawing to the full or building size, in the process of construction. Ham. Nav. Encyc.

Note: Expansion is also used adjectively, as in expansion joint, expansion gear, etc. Expansion curve, a curve the coördinates of which show the relation between the pressure and volume of expanding gas or vapor; esp. (Steam engine), that part of an indicator diagram which shows the declining pressure of the steam as it expands in the cylinder. -- Expansion gear (Stream Engine). a cut-off gear. See Illust. of Link motion. -- Automatic expansion gear or cut-off, one that is regulated by the governor, and varies the supply of steam to the engine with the demand for power. -- Fixed expansion gear, or Fixed cut-off, one that always operates at the same fixed point of the stroke. -- Expansion joint, or Expansion coupling (Mech. & Engin.), a yielding joint or coupling for so uniting parts of a machine or structure that expansion, as by heat, is prevented from causing injurious strains; as by heat, is prevented from causing injurious strains; as: (a) A side or set of rollers, at the end of bridge truss, to support it but allow end play. (b) A telescopic joint in a steam pipe, to permit one part of the pipe to slide within the other. (c) A clamp for holding a locomotive frame to the boiler while allowing lengthwise motion. -- Expansion valve (Steam Engine), a cut-off valve, to shut off steam from the cylinder before the end of each stroke.