Expansion joint
Expansion Ex*pan"sion, n. [L. expansio: cf. F. expansion.] 1. The act of expanding or spreading out; the condition of being expanded; dilation; enlargement. [1913 Webster]

2. That which is expanded; expanse; extend surface; as, the expansion of a sheet or of a lake; the expansion was formed of metal. [1913 Webster]

The starred expansion of the skies. --Beattie. [1913 Webster]

3. Space through which anything is expanded; also, pure space. [1913 Webster]

Lost in expansion, void and infinite. --Blackmore. [1913 Webster]

4. (Economics & Commmerce) an increase in the production of goods and services over time, and in the volume of business transactions, generally associated with an increase in employment and an increase in the money supply. Opposite of {contraction}.

Syn: economic expansion. [1913 Webster +PJC]

5. (Math.) The developed result of an indicated operation; as, the expansion of (a + b)^{2} is a^{2} + 2ab + b^{2}. [1913 Webster]

6. (Steam Engine) 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. [1913 Webster]

7. (Nav. Arch.) 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. [1913 Webster]

Note: Expansion is also used adjectively, as in expansion joint, expansion gear, etc. [1913 Webster]

8. an enlarged or extended version of something, such as a writing or discourse; as, the journal article is an expansion of the lecture she gave. [PJC]

9. an {expansion joint}. See below. [Colloq. or jargon] [PJC]

{Expansion curve}, a curve the co["o]rdinates 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} (Steam Engine). a cut-off gear. See Illust. of {Link motion}.

{Automatic expansion gear} or {Automatic 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: (a) A slide 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. (d) a strip of compressible material placed at intervals between blocks of poured concrete, as in roads or sidewalks.

{Expansion valve} (Steam Engine), a cut-off valve, to shut off steam from the cylinder before the end of each stroke. [1913 Webster]


The Collaborative International Dictionary of English. 2000.

Look at other dictionaries:

  • Expansion joint — For the railway specific expansion joints, see Breather switch. Expansion joint on a bridge An expansion joint or movement joint is an assembly designed to safely absorb the heat induced expansion and contraction of various construction materials …   Wikipedia

  • expansion joint — noun 1. : a coupling (as of steam pipes) designed to permit an endwise movement that compensates for expansion or contraction resulting from temperature changes 2. : a joint or gap (as in concrete work) designed to permit expansion or contraction …   Useful english dictionary

  • expansion joint — a joint between two parts of a structure, machine, etc., permitting expansion, as from heat, without structural damage. [1840 50] * * * …   Universalium

  • expansion joint — noun a joint that makes allowance for thermal expansion of the parts joined without distortion …   English new terms dictionary

  • expansion joint — any device containing one or more bellows used to absorb dimensional changes, such as those caused by thermal expansion or contraction of a pipeline, duct, or vessel …   Mechanics glossary

  • expansion joint — Device in piping designed to allow movement of the pipe caused by the pipe s expansion and contraction …   Dictionary of automotive terms

  • expansion joint — noun A structural separation between two building elements that allows free movement between the elements without damage to the system …   Wiktionary

  • pressure balanced expansion joint — a pressure balanced expansion joint is designed to absorb axial movement and/or lateral deflection while restraining the pressure thrust by means of tie devices interconnecting the flow bellows with an opposed bellows also subjected to line… …   Mechanics glossary

  • hinged expansion joint — a hinged expansion joint contains one bellows and is designed to permit angular rotation in one plane only, by the use of a pair of pins through hinge plates attached to the expansion joint ends. The hinges and hinge pins must be designed to… …   Mechanics glossary

  • internally guided expansion joint — an internally guided expansion joint is designed to provide axial guiding within the expansion joint by incorporating a heavy internal guide sleeve, with or without the use of bearing rings. The use of such expansion joints will assure… …   Mechanics glossary

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