text:
Contour line
From Wikipedia, the free encyclopedia
Jump to: navigation, search
This article is about lines of equal value in maps and diagrams. For more meanings of the word "contour", see Contour (disambiguation).
The bottom part of the diagram shows some contour lines with a straight line running through the location of the maximum value. The curve at the top represents the values along that straight line.
A three-dimensional surface, whose contour graph is below.
A two-dimensional contour graph of the three-dimensional surface in the above picture.
A contour line (also isocline, isopleth, isarithm, or equipotential curve) of a function of two variables is a curve along which the function has a constant value, so that the curve joins points of equal value.[1][2] It is a plane section of the three-dimensional graph of the function f(x, y) parallel to the x, y plane. In cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level.[3] A contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes.[4] The contour interval of a contour map is the difference in elevation between successive contour lines.[5]
More generally, a contour line for a function of two variables is a curve connecting points where the function has the same particular value.[2]
The gradient of the function is always perpendicular to the contour lines. When the lines are close together the magnitude of the gradient is large: the variation is steep. A level set is a generalization of a contour line for functions of any number of variables.
Contour lines are curved, straight or a mixture of both lines on a map describing the intersection of a real or hypothetical surface with one or more horizontal planes. The configuration of these contours allows map readers to infer relative gradient of a parameter and estimate that parameter at specific places. Contour lines may be either traced on a visible three-dimensional model of the surface, as when a photogrammetrist viewing a stereo-model plots elevation contours, or interpolated from estimated surface elevations, as when a computer program threads contours through a network of observation points of area centroids. In the latter case, the method of interpolation affects the reliability of individual isolines and their portrayal of slope, pits and peaks.[6]
Contents
[hide]
1 Types
1.1 Equidistant points
1.2 Isopleths
1.3 Meteorology
1.3.1 Barometric pressure
1.3.2 Temperature and related subjects
1.3.3 Rainfall and air moisture
1.3.4 Wind
1.3.5 Freeze and thaw
1.4 Physical geography and oceanography
1.4.1 Elevation and depth
1.4.1.1 Interpretation
1.4.2 Electrostatics
1.4.3 Magnetism
1.4.4 Oceanography
1.5 Geology
1.6 Environmental science
1.7 Ecology
1.8 Social sciences
1.9 Statistics
1.10 Thermodynamics, engineering, and other sciences
1.11 Other phenomena
2 History
3 Graphical design
4 Plan view versus profile view
5 Labeling contour maps
6 See also
7 References
8 External links
Types[edit]
Contour lines are often given specific names beginning "iso-" (Ancient Greek: ἴσος, translit. isos, lit. 'equal') according to the nature of the variable being mapped, although in many usages the phrase "contour line" is most commonly used. Specific names are most common in meteorology, where multiple maps with different variables may be viewed simultaneously. The prefix "iso-" can be replaced with "isallo-" to specify a contour line connecting points where a variable changes at the same rate during a given time period.
The words isoline and isarithm (ἀριθμός arithmos "number") are general terms covering all types of contour line. The word isogram (γράμμα gramma "writing or drawing") was proposed by Francis Galton in 1889 as a convenient generic designation for lines indicating equality of some physical condition or quantity;[7] but it commonly refers to a word without a repeated letter.
An isogon (from γωνία or gonia, meaning 'angle') is a contour line for a variable which measures direction. In meteorology and in geomagnetics, the term isogon has specific meanings which are described below. An isocline (from κλίνειν or klinein, meaning 'to lean or slope') is a line joining points with equal slope. In population dynamics and in geomagnetics, the terms isocline and isoclinic line have specific meanings which are described below.
Equidistant points[edit]
A curve of equidistant points is a set of points all at the same distance from a given point, line, or polyline. In this case the function whose value is being held constant along a contour line is a distance function.
Isopleths[edit]
In geography, the word isopleth (from πλῆθος or plethos, meaning 'quantity') is used for contour lines that depict a variable which cannot be measured at a point, but which instead must be calculated from data collected over an area. An example is population density, which can be calculated by dividing the population of a census district by the surface area of that district. Each calculated value is presumed to be the value of the variable at the centre of the area, and isopleths can then be drawn by a process of interpolation. The idea of an isopleth map can be compared with that of a choropleth map.[8][9][10]
In meteorology, the word isopleth is used for any type of contour line.[11]
Meteorology[edit]
Isohyetal map of precipitation
Meteorological contour lines are based on interpolation of the point data received from weather stations and weather satellites. Weather stations are seldom exactly positioned at a contour line (when they are, this indicates a measurement precisely equal to the value of the contour). Instead, lines are drawn to best approximate the locations of exact values, based on the scattered information points available.
Meteorological contour maps may present collected data such as actual air pressure at a given time, or generalized data such as average pressure over a period of time, or forecast data such as predicted air pressure at some point in the future
Thermodynamic diagrams use multiple overlapping contour sets (including isobars and isotherms) to present a picture of the major thermodynamic factors in a weather system.
Barometric pressure[edit]
Loop showing the motion of a cold front by the movement of isallobars
An isobar (from βάρος or baros, meaning 'weight') is a line of equal or constant pressure on a graph, plot, or map; an isopleth or contour line of pressure. More accurately, isobars are lines drawn on a map joining places of equal average atmospheric pressure reduced to sea level for a specified period of time. In meteorology, the barometric pressures shown are reduced to sea level, not the surface pressures at the map locations.[12] The distribution of isobars is closely related to the magnitude and direction of the wind field, and can be used to predict future weather patterns. Isobars are commonly used in television weather reporting.
Isallobars are lines joining points of equal pressure change during a specific time interval.[13] These can be divided into anallobars, lines joining points of equal pressure increase during a specific time interval,[14] and katallobars, lines joining points of equal pressure decrease.[15] In general, weather systems move along an axis joining high and low isallobaric centers.[16] Isallobaric gradients are important components of the wind as they increase or decrease the geostrophic wind.
An isopycnal is a line of constant density. An isoheight or isohypse is a line of constant geopotential height on a constant pressure surface chart. Isohypse and isoheight are simply known as lines showing equal pressure on a map.
Temperature and related subjects[edit]
The 10 °C (50 °F) mean isotherm in July, marked by the red line, is commonly used to define the border of the Arctic region
An isotherm (from θέρμη or thermē, meaning 'heat') is a line that connects points on a map that have the same temperature. Therefore, all points through which an isotherm passes have the same or equal temperatures at the time indicated.[17][2] An isotherm at 0 °C is called the freezing level. The term was coined by the Prussian geographer and naturalist Alexander von Humboldt, who as part of his research into the geographical distribution of plants published the first map of isotherms in Paris, in 1817.[18]
An isogeotherm is a line of equal mean annual temperature. An isocheim is a line of equal mean winter temperature, and an isothere is a line of equal mean summer temperature.
An isohel (from ἥλιος or helios, meaning 'Sun') is a line of equal or constant solar radiation.
Rainfall and air moisture[edit]
An isohyet or isohyetal line (from ὕετος or huetos, meaning 'rain') is a line joining points of equal rainfall on a map in a given period . A map with isohyets is called an isohyetal map.
An isohume is a line of constant relative humidity, while a isodrosotherm (from δρόσος or drosos, meaning 'dew', and θέρμη or therme, meaning 'heat') is a line of equal or constant dew point.
An isoneph is a line indicating equal cloud cover.
An isochalaz is a line of constant frequency of hail storms, and an isobront is a line drawn through geographical points at which a given phase of thunderstorm activity occurred simultaneously.
Snow cover is frequently shown as a contour-line map.
Wind[edit]
An isotach (from ταχύς or tachus, meaning 'fast') is a line joining points with constant wind speed. In meteorology, the term isogon refers to a line of constant wind direction.
Freeze and thaw[edit]
An isopectic line denotes equal dates of ice formation each winter, and an isotac denotes equal dates of thawing.
Physical geography and oceanography[edit]
Elevation and depth[edit]
Topographic map of Stowe, Vermont. The brown contour lines represent the elevation. The contour interval is 20 feet.
Contours are one of several common methods used to denote elevation or altitude and depth on maps. From these contours, a sense of the general terrain can be determined. They are used at a variety of scales, from large-scale engineering drawings and architectural plans, through topographic maps and bathymetric charts, up to continental-scale maps.
"Contour line" is the most common usage in cartography, but isobath for underwater depths on bathymetric maps and isohypse for elevations are also used.
In cartography, the contour interval is the elevation difference between adjacent contour lines. The contour interval should be the same over a single map. When calculated as a ratio against the map scale, a sense of the hilliness of the terrain can be derived.
Interpretation[edit]
There are several rules to note when interpreting terrain contour lines:
The rule of Vs: sharp-pointed vees usually are in stream valleys, with the drainage channel passing through the point of the vee, with the vee pointing upstream. This is a consequence of erosion.
The rule of Os: closed loops are normally uphill on the inside and downhill on the outside, and the innermost loop is the highest area. If a loop instead represents a depression, some maps note this by short lines radiating from the inside of the loop, called "hachures".
Spacing of contours: close contours indicate a steep slope; distant contours a shallow slope. Two or more contour lines merging indicates a cliff. By counting the number of contours that cross a segment of a stream, the stream gradient can be approximated.
Of course, to determine differences in elevation between two points, the contour interval, or distance in altitude between two adjacent contour lines, must be known, and this is normally stated in the map key. Usually contour intervals are consistent throughout a map, but there are exceptions. Sometimes intermediate contours are present in flatter areas; these can be dashed or dotted lines at half the noted contour interval. When contours are used with hypsometric tints on a small-scale map that includes mountains and flatter low-lying areas, it is common to have smaller intervals at lower elevations so that detail is shown in all areas. Conversely, for an island which consists of a plateau surrounded by steep cliffs, it is possible to use smaller intervals as the height increases.[19]
Electrostatics[edit]
An isopotential map is a measure of electrostatic potential in space, often depicted in two dimensions with the electostatic charges inducing that electric potential. The term equipotential line or isopotential line refers to a curve of constant electric potential. Whether crossing an equipotential line represents ascending or descending the potential is inferred from the labels on the charges. In three dimensions, equipotential surfaces may be depicted with a two dimensional cross-section, showing equipotential lines at the intersection of the surfaces and the cross-section.
The general mathematical term level set is often used to describe the full collection of points having a particular potential, especially in higher dimensional space.
Magnetism[edit]
Isogonic lines for the year 2000. The agonic lines are thicker and labeled with "0".
In the study of the Earth's magnetic field, the term isogon or isogonic line refers to a line of constant magnetic declination, the variation of magnetic north from geographic north. An agonic line is drawn through points of zero magnetic declination. An isoporic line refers to a line of constant annual variation of magnetic declination .[20]
An isoclinic line connects points of equal magnetic dip, and an aclinic line is the isoclinic line of magnetic dip zero.
An isodynamic line (from δύναμις or dynamis meaning 'power') connects points with the same intensity of magnetic force.
Oceanography[edit]
Besides ocean depth, oceanographers use contour to describe diffuse variable phenomena much as meteorologists do with atmospheric phenomena. In particular, isobathytherms are lines showing depths of water with equal temperature, isohalines show lines of equal ocean salinity, and Isopycnals are surfaces of equal water density.
Geology[edit]
Various geological data are rendered as contour maps in structural geology, sedimentology, stratigraphy and economic geology. Contour maps are used to show the below ground surface of geologic strata, fault surfaces (especially low angle thrust faults) and unconformities. Isopach maps use isopachs (lines of equal thickness) to illustrate variations in thickness of geologic units.
Environmental science[edit]
In discussing pollution, density maps can be very useful in indicating sources and areas of greatest contamination. Contour maps are especially useful for diffuse forms or scales of pollution. Acid precipitation is indicated on maps with isoplats. Some of the most widespread applications of environmental science contour maps involve mapping of environmental noise (where lines of equal sound pressure level are denoted isobels[21]), air pollution, soil contamination, thermal pollution and groundwater contamination. By contour planting and contour ploughing, the rate of water runoff and thus soil erosion can be substantially reduced; this is especially important in riparian zones.
Ecology[edit]
An isoflor is an isopleth contour connecting areas of comparable biological diversity. Usually, the variable is the number of species of a given genus or family that occurs in a region. Isoflor maps are thus used to show distribution patterns and trends such as centres of diversity.[22]
Social sciences[edit]
From economics, an indifference map with three indifference curves shown. All points on a particular indifference curve have the same value of the utility function, whose values implicitly come out of the page in the unshown third dimension.
In economics, contour lines can be used to describe features which vary quantitatively over space. An isochrone shows lines of equivalent drive time or travel time to a given location and is used in the generation of isochrone maps. An isotim shows equivalent transport costs from the source of a raw material, and an isodapane shows equivalent cost of travel time.
A single production isoquant (convex) and a single isocost curve (linear). Labor usage is plotted horizontally and physical capital usage is plotted vertically.
Contour lines are also used to display non-geographic information in economics. Indifference curves (as shown at left) are used to show bundles of goods to which a person would assign equal utility. An isoquant (in the image at right) is a curve of equal production quantity for alternative combinations of input usages, and an isocost curve (also in the image at right) shows alternative usages having equal production costs.
In political science an analogous method is used in understanding coalitions (for example the diagram in Laver and Shepsle's work[23]).
In population dynamics, an isocline shows the set of population sizes at which the rate of change, or partial derivative, for one population in a pair of interacting populations is zero.
Statistics[edit]
In statistics, isodensity lines [24] or isodensanes are lines that join points with the same value of a probability density. Isodensanes are used to display bivariate distributions. For example, for a bivariate elliptical distribution the isodensity lines are ellipses.
Thermodynamics, engineering, and other sciences[edit]
Various types of graphs in thermodynamics, engineering, and other sciences use isobars (constant pressure), isotherms (constant temperature), isochors (constant specific volume), or other types of isolines, even though these graphs are usually not related to maps. Such isolines are useful for representing more than two dimensions (or quantities) on two-dimensional graphs. Common examples in thermodynamics are some types of phase diagrams.
Isoclines are used to solve ordinary differential equations.
In interpreting radar images, an isodop is a line of equal Doppler velocity, and an isoecho is a line of equal radar reflectivity.
Other phenomena[edit]
isochasm: aurora equal occurrence
isochor: volume
isodose: Absorbed dose of radiation
isophene: biological events occurring with coincidence such as plants flowering
isophote: illuminance
mobile telephony: mobile received power and cell coverage area
History[edit]
The idea of lines that join points of equal value was rediscovered several times. The oldest known isobath (contour line of constant depth) is found on a map dated 1584 of the river Spaarne, near Haarlem, by Dutchman Pieter Bruinsz.[25] In 1701, Edmond Halley used such lines (isogons) on a chart of magnetic variation.[26] The Dutch engineer Nicholas Cruquius drew the bed of the river Merwede with lines of equal depth (isobaths) at intervals of 1 fathom in 1727, and Philippe Buache used them at 10-fathom intervals on a chart of the English Channel that was prepared in 1737 and published in 1752. Such lines were used to describe a land surface (contour lines) in a map of the Duchy of Modena and Reggio by Domenico Vandelli in 1746, and they were studied theoretically by Ducarla in 1771, and Charles Hutton used them in the Schiehallion experiment. In 1791, a map of France by J. L. Dupain-Triel used contour lines at 20-metre intervals, hachures, spot-heights and a vertical section. In 1801, the chief of the Corps of Engineers, Haxo, used contour lines at the larger scale of 1:500 on a plan of his projects for Rocca d'Aufo.[27][28][29]
By around 1843, when the Ordnance Survey started to regularly record contour lines in Great Britain and Ireland, they were already in general use in European countries. Isobaths were not routinely used on nautical charts until those of Russia from 1834, and those of Britain from 1838.[27][30][31]
When maps with contour lines became common, the idea spread to other applications. Perhaps the latest to develop are air quality and noise pollution contour maps, which first appeared in the United States in approximately 1970, largely as a result of national legislation requiring spatial delineation of these parameters. In 2007, Pictometry International was the first to allow users to dynamically generate elevation contour lines to be laid over oblique images.
Graphical design[edit]
For features specific to topography, see Terrain cartography § Contour lines, and Topographic map § Conventions.
To maximize readability of contour maps, there are several design choices available to the map creator, principally line weight, line color, line type and method of numerical marking.
Line weight is simply the darkness or thickness of the line used. This choice is made based upon the least intrusive form of contours that enable the reader to decipher the background information in the map itself. If there is little or no content on the base map, the contour lines may be drawn with relatively heavy thickness. Also, for many forms of contours such as topographic maps, it is common to vary the line weight and/or color, so that a different line characteristic occurs for certain numerical values. For example, in the topographic map above, the even hundred foot elevations are shown in a different weight from the twenty foot intervals.
Line color is the choice of any number of pigments that suit the display. Sometimes a sheen or gloss is used as well as color to set the contour lines apart from the base map. Line colour can be varied to show other information.
Line type refers to whether the basic contour line is solid, dashed, dotted or broken in some other pattern to create the desired effect. Dotted or dashed lines are often used when the underlying base map conveys very important (or difficult to read) information. Broken line types are used when the location of the contour line is inferred.
Numerical marking is the manner of denoting the arithmetical values of contour lines. This can be done by placing numbers along some of the contour lines, typically using interpolation for intervening lines. Alternatively a map key can be produced associating the contours with their values.
If the contour lines are not numerically labeled and adjacent lines have the same style (with the same weight, color and type), then the direction of the gradient cannot be determined from the contour lines alone. However, if the contour lines cycle through three or more styles, then the direction of the gradient can be determined from the lines. The orientation of the numerical text labels is often used to indicate the direction of the slope.
Plan view versus profile view[edit]
See also: Topographic profile
Most commonly contour lines are drawn in plan view, or as an observer in space would view the Earth's surface: ordinary map form. However, some parameters can often be displayed in profile view showing a vertical profile of the parameter mapped. Some of the most common parameters mapped in profile are air pollutant concentrations and sound levels. In each of those cases it may be important to analyze (air pollutant concentrations or sound levels) at varying heights so as to determine the air quality or noise health effects on people at different elevations, for example, living on different floor levels of an urban apartment. In actuality, both plan and profile view contour maps are used in air pollution and noise pollution studies.
Labeling contour maps[edit]
Contour map labeled aesthetically in an "elevation up" manner.
Labels are a critical component of elevation maps. A properly labeled contour map helps the reader to quickly interpret the shape of the terrain. If numbers are placed close to each other, it means that the terrain is steep. Labels should be placed along a slightly curved line "pointing" to the summit or nadir, from several directions if possible, making the visual identification of the summit or nadir easy.[32][33] Contour labels can be oriented so a reader is facing uphill when reading the label.
Manual labeling of contour maps is a time-consuming process, however, there are a few software systems that can do the job automatically and in accordance with cartographic conventions, called automatic label placement.
See also[edit]
Atlas portal
Aeronautical chart
Cartogram
Compass rose
Dymaxion map
Estate map
Fall line (topography)
Fantasy map
Floor plan
Geologic map
Map design
Marching squares
Nautical chart
Pictorial maps
Planform
Plat
Reversed map
Road atlas
Street map
TERCOM
Thematic map
Topographic map
World map
References[edit]
Jump up ^ Courant, Richard, Herbert Robbins, and Ian Stewart. What Is Mathematics?: An Elementary Approach to Ideas and Methods. New York: Oxford University Press, 1996. p. 344.
^ Jump up to: a b c Hughes-Hallett, Deborah; McCallum, William G.; Gleason, Andrew M. (2013). Calculus : Single and Multivariable (6 ed.). John wiley. ISBN 978-0470-88861-2.
Jump up ^ Merriam Webster - contour line
Jump up ^ contour map Merriam Webster
Jump up ^ Tracy, John C. Plane Surveying; A Text-Book and Pocket Manual. New York: J. Wiley & Sons, 1907. p. 337.
Jump up ^ Davis, John C., 1986, Statistics and data analysis in geology, Wiley ISBN 0-471-08079-9
Jump up ^ Oxford English Dictionary; see also: Nature, 40, 1889, p.651.
Jump up ^ Robinson AH (1971). "The genealogy of the isopleth". Cartographic Journal. 8: 49–53.
Jump up ^ T. Slocum, R. McMaster, F. Kessler, and H. Howard, Thematic Cartography and Geographic Visualization, 2nd edition, Pearson, 2005, ISBN 0-13-035123-7, p. 272.
Jump up ^ ArcGIS, Isopleth: Contours, 2013.
Jump up ^ NOAA's National Weather Service, Glossary.
Jump up ^ Edward J. Hopkins, Ph.D. (1996-06-10). "Surface Weather Analysis Chart". University of Wisconsin. Retrieved 2007-05-10.
Jump up ^ World Meteorological Organisation. "Isallobar". Eumetcal. Archived from the original on 16 April 2014. Retrieved 12 April 2014.
Jump up ^ World Meteorological Organisation. "Anallobar". Eumetcal. Archived from the original on 24 September 2015. Retrieved 12 April 2014.
Jump up ^ World Meteorological Organisation. "Katallobar". Eumetcal. Archived from the original on 5 February 2008. Retrieved 12 April 2014.
Jump up ^ "Forecasting weather system movement with pressure tendency". Chapter 13 - Weather Forecasting. Lyndon State College Atmospheric Sciences. Retrieved 12 April 2014.
Jump up ^ DataStreme Atmosphere (2008-04-28). "Air Temperature Patterns". American Meteorological Society. Archived from the original on 2008-05-11. Retrieved 2010-02-07.
Jump up ^ Munzar, Jan (1967-09-01). "Alexander Von Humboldt and His Isotherms". Weather. 22 (9): 360–363. Bibcode:1967Wthr...22..360M. doi:10.1002/j.1477-8696.1967.tb02989.x. ISSN 1477-8696.
Jump up ^ Sark (Sercq), D Survey, Ministry of Defence, Series M 824, Sheet Sark, Edition 4 GSGS, 1965, OCLC OCLC 27636277. Scale 1:10,560. Contour intervals: 50 feet up to 200, 20 feet from 200 to 300, and 10 feet above 300.
Jump up ^ "isoporic line". 1946. Retrieved 2015-07-20.
Jump up ^ "Isobel". 2005-01-05. Retrieved 2010-04-25.
Jump up ^ Specht, Raymond. Heathlands and related shrublands: Analytical studies. Elsevier. pp. 219–220.
Jump up ^ Laver, Michael and Kenneth A. Shepsle (1996) Making and breaking governments pictures.
Jump up ^ Fernández, Antonio (2011). "A Generalized Regression Methodology for Bivariate Heteroscedastic Data". Communications in Statistics - Theory and Methods. Taylor and Francis. 40 (4): 601. doi:10.1080/03610920903444011.
Jump up ^ Morato-Moreno, Manuel (2017). "Orígenes de la representación topográfica del terreno en algunos mapas hispanoamericanos del s. XVI". Boletín de la Asociación de Geógrafos Españoles.
Jump up ^ Thrower, N. J. W. Maps and Civilization: Cartography in Culture and Society, University of Chicago Press, 1972, revised 1996, page 97; and Jardine, Lisa Ingenious Pursuits: Building the Scientific Revolution, Little, Brown, and Company, 1999, page 31.
^ Jump up to: a b R. A. Skelton, "Cartography", History of Technology, Oxford, vol. 6, pp. 612-614, 1958.
Jump up ^ Colonel Berthaut, La Carte de France, vol. 1, p. 139, quoted by Close.
Jump up ^ C. Hutton, "An account of the calculations made from the survey and measures taken at Schehallien, in order to ascertain the mean density of the Earth", Philosophical Transactions of the Royal Society of London, vol. 68, pp. 756-757
Jump up ^ C. Close, The Early Years of the Ordnance Survey, 1926, republished by David and Charles, 1969, ISBN 0-7153-4477-3, pp. 141-144.
Jump up ^ T. Owen and E. Pilbeam, Ordnance Survey: Map Makers to Britain since 1791, HMSO, 1992, ISBN 0-11-701507-5.
Jump up ^ Imhof, E., "Die Anordnung der Namen in der Karte," Annuaire International de Cartographie II, Orell-Füssli Verlag, Zürich, 93-129, 1962.
Jump up ^ Freeman, H., "Computer Name Placement," ch. 29, in Geographical Information Systems, 1, D.J. Maguire, M.F. Goodchild, and D.W. Rhind, John Wiley, New York, 1991, 449-460.
External links[edit]
Wikimedia Commons has media related to Contour lines.
Forthright's Phrontistery
Authority control
GND: 4261534-3
Retrieved from "https://en.wikipedia.org/w/index.php?title=Contour_line&oldid=826276433"
Categories:
Cartography
Curves
Multivariable calculus
Topography
Hidden categories:
Articles containing Ancient Greek-language text
Pages using div col without cols and colwidth parameters
Wikipedia articles with GND identifiers
Navigation menu
Personal tools
Not logged in
Talk
Contributions
Create account
Log in
Namespaces
Article
Talk
Variants
Views
Read
Edit
View history
More
Search
Navigation
Main page
Contents
Featured content
Current events
Random article
Donate to Wikipedia
Wikipedia store
Interaction
Help
About Wikipedia
Community portal
Recent changes
Contact page
Tools
What links here
Related changes
Upload file
Special pages
Permanent link
Page information
Wikidata item
Cite this page
Print/export
Create a book
Download as PDF
Printable version
In other projects
Wikimedia Commons
Languages
العربية
Azərbaycanca
Беларуская
Беларуская (тарашкевіца)
Български
Català
Čeština
Deutsch
Eesti
Español
Esperanto
Euskara
فارسی
Français
Gaeilge
한국어
Հայերեն
हिन्दी
Hrvatski
Ido
Bahasa Indonesia
ქართული
Қазақша
Kreyòl ayisyen
Кыргызча
Latviešu
Lietuvių
मराठी
Bahasa Melayu
မြန်မာဘာသာ
Nederlands
日本語
Norsk
Norsk nynorsk
Polski
Português
Română
Русский
Shqip
සිංහල
Simple English
Slovenčina
Slovenščina
Српски / srpski
Svenska
தமிழ்
Türkçe
Українська
Tiếng Việt
粵語
中文
42 more
Edit links
This page was last edited on 18 February 2018, at 06:19.
Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.
Privacy policy
About Wikipedia
Disclaimers
Contact Wikipedia
Developers
Cookie statement
Mobile view
Enable previews

values: mw-page-base noprint

values: mw-head-base noprint

values: firstHeading firstHeading en

values: siteSub noprint

values: jump-to-nav mw-jump

values:
/wiki/Contour_(disambiguation)
mw-redirect mw-disambig
Contour (disambiguation)

attrs: role class

values:
note
hatnote navigation-not-searchable

attrs: class style

values:
/wiki/Mean_sea_level
mw-redirect
Mean sea level

values:
/wiki/Ancient_Greek_language
mw-redirect
Ancient Greek language

values:
/wiki/Romanization_of_Ancient_Greek
mw-redirect
Romanization of Ancient Greek

values:
grc-Latn
Ancient Greek-language transliteration
grc-Latn

values:
grc-Latn
Ancient Greek language text
grc-Latn

values:
/wiki/Distance_function
mw-redirect
Distance function

values:
/wiki/Weather_maps
mw-redirect
Weather maps

values:
/wiki/Barometric_pressure
mw-redirect
Barometric pressure

values: Edit section: Temperature and related subjects

values:
/wiki/Arctic_region
mw-redirect
Arctic region

values:
/wiki/Solar_radiation
mw-redirect
Solar radiation

values: Edit section: Physical geography and oceanography

values:
/wiki/Foot_(length)
mw-redirect
Foot (length)

values:
/wiki/Cartographic_relief_depiction
mw-redirect
Cartographic relief depiction

values:
/wiki/Topographic_maps
mw-redirect
Topographic maps

values:
/wiki/Bathymetric_charts
mw-redirect
Bathymetric charts

values:
/wiki/Contour_planting
mw-redirect
Contour planting

values:
/wiki/Contour_ploughing
mw-redirect
Contour ploughing

values:
/wiki/Water_runoff
mw-redirect
Water runoff

values:
/wiki/Utility_function
mw-redirect
Utility function

values:
/wiki/Indifference_curves
mw-redirect
Indifference curves

values:
/wiki/Probability_density
mw-redirect
Probability density

values:
/wiki/Bivariate_distribution
mw-redirect
Bivariate distribution

values: Edit section: Thermodynamics, engineering, and other sciences

values:
/wiki/Ordinary_differential_equations
mw-redirect
Ordinary differential equations

values:
/wiki/Aurora_(astronomy)
mw-redirect
Aurora (astronomy)

values:
/wiki/Dutch_(ethnic_group)
mw-redirect
Dutch (ethnic group)

values:
/wiki/Air_quality
mw-redirect
Air quality

values:
/wiki/Gloss_(paint)
mw-redirect
Gloss (paint)

values: Edit section: Plan view versus profile view

values:
/wiki/Sound_exposure_level
mw-redirect
Sound exposure level

values:
/wiki/Noise_health_effects
mw-redirect
Noise health effects

values:
/wiki/Labeling_(map_design)
mw-redirect
Labeling (map design)

values: display:table-cell;padding:0.2em 0.2em 0.2em 0.3em;vertical-align:middle

values: margin:0.5em 0 0.5em 1em;border:solid #aaa 1px

values:
/wiki/Pictorial_maps
mw-redirect
Pictorial maps

values:
/wiki/Reversed_map
mw-redirect
Reversed map

values: div-col columns column-count column-count-2

values: -moz-column-count: 2; -webkit-column-count: 2; column-count: 2;

values:
/wiki/World_Meteorological_Organisation
mw-redirect
World Meteorological Organisation

values:
nofollow
external text
//www.worldcat.org/issn/1477-8696

values:
/wiki/Online_Computer_Library_Center
mw-redirect
Online Computer Library Center

values:
nofollow
external text
https://www.worldcat.org/oclc/27636277

values: -moz-column-width: 35em; -webkit-column-width: 35em; column-width: 35em; list-style-type: decimal;

values:
nofollow
external text
http://phrontistery.info/contour.html

values:
nofollow
external text
https://d-nb.info/gnd/4261534-3

values: Category:Articles containing Ancient Greek-language text

values: Category:Pages using div col without cols and colwidth parameters

values: Category:Wikipedia articles with GND identifiers

values: Discussion about edits from this IP address [ctrl-alt-n]

values: A list of edits made from this IP address [ctrl-alt-y]

values: You are encouraged to create an account and log in; however, it is not mandatory

values:
/wiki/Contour_line
View the content page [ctrl-alt-c]
c

values:
/wiki/Special:Random
Load a random article [ctrl-alt-x]
x

values: portal navigation p-navigation p-navigation-label

values: Guidance on how to use and edit Wikipedia

values: About the project, what you can do, where to find things

values: A list of recent changes in the wiki [ctrl-alt-r]

values: portal navigation p-interaction p-interaction-label

values: List of all English Wikipedia pages containing links to this page [ctrl-alt-j]

values: Recent changes in pages linked from this page [ctrl-alt-k]

values:
/wiki/Wikipedia:File_Upload_Wizard
Upload files [ctrl-alt-u]
u

values: A list of all special pages [ctrl-alt-q]

values: Permanent link to this revision of the page

values: Link to connected data repository item [ctrl-alt-g]

values: Printable version of this page [ctrl-alt-p]

values: خط منسوب – Arabic

values:
interlanguage-link interwiki-az
display: none;

values:
interlanguage-link interwiki-be
display: none;

values: Ізалінія – Belarusian (Taraškievica orthography)

values:
interlanguage-link interwiki-be-x-old
display: none;

values: Контурна линия – Bulgarian

values:
interlanguage-link interwiki-bg
display: none;

values:
interlanguage-link interwiki-ca
display: none;

values:
https://cs.wikipedia.org/wiki/Izolinie
Izolinie – Czech
cs
cs
interlanguage-link-target

values:
interlanguage-link interwiki-cs
display: none;

values:
https://de.wikipedia.org/wiki/Isolinie
Isolinie – German
de
de
interlanguage-link-target

values:
interlanguage-link interwiki-de
display: none;

values:
https://et.wikipedia.org/wiki/Samajoon
Samajoon – Estonian
et
et
interlanguage-link-target

values:
interlanguage-link interwiki-et
display: none;

values:
https://eo.wikipedia.org/wiki/Izolinio
Izolinio – Esperanto
eo
eo
interlanguage-link-target

values:
interlanguage-link interwiki-eo
display: none;

values:
https://eu.wikipedia.org/wiki/Isolinea
Isolinea – Basque
eu
eu
interlanguage-link-target

values:
interlanguage-link interwiki-eu
display: none;

values: خط تراز – Persian

values:
interlanguage-link interwiki-fa
display: none;

values:
interlanguage-link interwiki-ga
display: none;

values:
interlanguage-link interwiki-ko
display: none;

values: Իզոգծեր – Armenian

values:
interlanguage-link interwiki-hy
display: none;

values: समोच्च रेखा – Hindi

values:
https://hr.wikipedia.org/wiki/Izolinije
Izolinije – Croatian
hr
hr
interlanguage-link-target

values:
interlanguage-link interwiki-hr
display: none;

values:
https://io.wikipedia.org/wiki/Izolineo
Izolineo – Ido
io
io
interlanguage-link-target

values:
interlanguage-link interwiki-io
display: none;

values: იზოხაზები – Georgian

values:
interlanguage-link interwiki-ka
display: none;

values: Жер бедерін бейнелеу сызықтары – Kazakh

values:
interlanguage-link interwiki-kk
display: none;

values:
interlanguage-link interwiki-ht
display: none;

values: Изосызыктар – Kyrgyz

values:
interlanguage-link interwiki-ky
display: none;

values:
interlanguage-link interwiki-lv
display: none;

values:
https://lt.wikipedia.org/wiki/Izolinija
Izolinija – Lithuanian
lt
lt
interlanguage-link-target

values:
interlanguage-link interwiki-lt
display: none;

values: समोच्चता रेषा – Marathi

values:
interlanguage-link interwiki-mr
display: none;

values:
https://ms.wikipedia.org/wiki/Kontur
Kontur – Malay
ms
ms
interlanguage-link-target

values: ကွန်တိုမျဉ်း – Burmese

values:
interlanguage-link interwiki-my
display: none;

values:
https://nl.wikipedia.org/wiki/Isopleet
Isopleet – Dutch
nl
nl
interlanguage-link-target

values:
interlanguage-link interwiki-nl
display: none;

values:
interlanguage-link interwiki-ja
display: none;

values:
https://no.wikipedia.org/wiki/Isoplett
Isoplett – Norwegian
no
no
interlanguage-link-target

values:
interlanguage-link interwiki-no
display: none;

values:
https://nn.wikipedia.org/wiki/Isoplet
Isoplet – Norwegian Nynorsk
nn
nn
interlanguage-link-target

values:
interlanguage-link interwiki-nn
display: none;

values:
https://pl.wikipedia.org/wiki/Izolinia
Izolinia – Polish
pl
pl
interlanguage-link-target

values:
interlanguage-link interwiki-pl
display: none;

values:
https://pt.wikipedia.org/wiki/Isolinha
Isolinha – Portuguese
pt
pt
interlanguage-link-target

values:
https://ro.wikipedia.org/wiki/Izolinie
Izolinie – Romanian
ro
ro
interlanguage-link-target

values:
interlanguage-link interwiki-ro
display: none;

values: Изолиния – Russian

values:
https://sq.wikipedia.org/wiki/Izovijat
Izovijat – Albanian
sq
sq
interlanguage-link-target

values:
interlanguage-link interwiki-sq
display: none;

values: සමෝච්ච රේඛාව – Sinhala

values:
interlanguage-link interwiki-si
display: none;

values:
interlanguage-link interwiki-simple
display: none;

values:
interlanguage-link interwiki-sk
display: none;

values:
interlanguage-link interwiki-sl
display: none;

values: Изолиније – Serbian

values:
interlanguage-link interwiki-sr
display: none;

values:
https://sv.wikipedia.org/wiki/Isaritm
Isaritm – Swedish
sv
sv
interlanguage-link-target

values:
interlanguage-link interwiki-sv
display: none;

values: சமவுயரக் கோட்டு வரைபு – Tamil

values:
interlanguage-link interwiki-ta
display: none;

values:
interlanguage-link interwiki-tr
display: none;

values: Ізолінія – Ukrainian

values:
interlanguage-link interwiki-uk
display: none;

values:
interlanguage-link interwiki-vi
display: none;

values:
interlanguage-link interwiki-zh-yue
display: none;

values: All languages (initial selection from common choices by you and others)

values: /static/images/wikimedia-button-1.5x.png 1.5x, /static/images/wikimedia-button-2x.png 2x

values: /static/images/poweredby_mediawiki_132x47.png 1.5x, /static/images/poweredby_mediawiki_176x62.png 2x

values: mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject page-Contour_line rootpage-Contour_line skin-vector action-view


text:
Brake fluid
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Brake fluid is a type of hydraulic fluid used in hydraulic brake and hydraulic clutch applications in automobiles, motorcycles, light trucks, and some bicycles. It is used to transfer force into pressure, and to amplify braking force. It works because liquids are not appreciably compressible—in their natural state, the component molecules do not have internal voids and the molecules pack together well, so bulk forces are directly transferred to compress the fluid's chemical bonds.
Most brake fluids used today are glycol-ether based, but mineral oil (Citroën/Rolls-Royce liquide hydraulique minéral (LHM)) and silicone (DOT 5) based fluids are also available.[1]
Brake fluids must meet certain requirements as defined by various standards set by organizations such as the SAE, or local government equivalents. For example, most brake fluid sold in North America is classified by the US Department of Transportation (DOT) under its own ratings such as "DOT 3" and "DOT 4". Their classifications broadly reflect the concerns addressed by the SAE's specifications, but with local details - Alaska and the Azores have different normal temperature and humidity ranges to consider, for example; many countries defer explicitly to the SAE specifications, or simply refer to "best practice" which in application would defer to SAE standard. All approved fluids must be colorless or amber to be acceptable for street use in the U.S, except for DOT 5 silicone, which must be purple.
Contents
[hide]
1 Characteristics
1.1 Boiling point
1.2 Viscosity
1.3 Corrosion
1.4 Compressibility
2 Service and maintenance
3 Components
3.1 Castor oil-based (pre-DOT, DOT 2)
3.2 Glycol-based (DOT 3, 4, 5.1)
3.3 Silicone-based (DOT 5)
4 See also
5 References
6 External links
Characteristics[edit]
Brake fluids must have certain characteristics and meet certain quality standards for the braking system to work properly.
Boiling point[edit]
Brake fluid is subjected to very high temperatures, especially in the wheel cylinders of drum brakes and disk brake calipers. It must have a high boiling point to avoid vaporizing in the lines. This vaporization is a problem because vapor is highly compressible relative to liquid, and therefore negates the hydraulic transfer of braking force - so the brakes will fail to stop the vehicle. [2]
Quality standards refer to a brake fluid's "dry" and "wet" boiling points. The wet boiling point, which is usually much lower (although above most normal service temperatures), refers to the fluid's boiling point after absorbing a certain amount of moisture. This is several (single digit) percent, varying from formulation to formulation. Glycol-ether (DOT 3, 4, and 5.1) brake fluids are hygroscopic (water absorbing), which means they absorb moisture from the atmosphere under normal humidity levels. Non-hygroscopic fluids (e.g. silicone/DOT 5 and mineral oil based formulations), are hydrophobic, and can maintain an acceptable boiling point over the fluid's service life.
Silicone based fluid is more compressible than glycol based fluid, leading to brakes with a spongy feeling. [3] It can potentially suffer phase separation/water pooling and freezing/boiling in the system over time - the main reason single phase hygroscopic fluids are used.[citation needed]
Characteristics of common braking fluids[4][5]
Dry boiling point
Wet boiling point
Viscosity limit
Primary constituent
DOT 2 190 °C (374 °F) 140 °C (284 °F) ? castor oil/alcohol
DOT 3 205 °C (401 °F) 140 °C (284 °F) 1500 mm2/s glycol ether
DOT 4 230 °C (446 °F) 155 °C (311 °F) 1800 mm2/s glycol ether/borate ester
LHM+ 249 °C (480 °F) 249 °C (480 °F) 1200 mm2/s [6] mineral oil
DOT 5 260 °C (500 °F) 180 °C (356 °F) 900 mm2/s silicone
DOT 5.1 260 °C (500 °F) 180 °C (356 °F) 900 mm2/s glycol ether/borate ester
Wet boiling point defined as 3.7% water by volume.
Viscosity[edit]
For reliable, consistent brake system operation, brake fluid must maintain a constant viscosity under a wide range of temperatures, including extreme cold. This is especially important in systems with an anti-lock braking system (ABS), traction control, and stability control (ESP), as these systems may use a valve with a time-based approach, rather than measuring pressure or volume to control the amount of fluid transferred.
Corrosion[edit]
Brake fluids must not corrode the metals used inside components such as calipers, wheel cylinders, master cylinders and ABS control valves. They must also protect against corrosion as moisture enters the system. Additives (corrosion inhibitors) are added to the base fluid to accomplish this. Silicone is less corrosive to paintwork unlike glycol-ether based DOT fluids.[7]
The advantage of the Citroën LHM mineral oil based brake fluid is the absence of corrosion. Seals may wear out at high mileages but otherwise these systems have exceptional longevity. It cannot be used as a substitute without changing seals due to incompatibility.[8][not in citation given]
Compressibility[edit]
Brake fluids must maintain a low level of compressibility, even with varying temperatures to accommodate different environmental conditions. This is important to ensure consistent brake pedal feel. As compressibility increases, more brake pedal travel is necessary for the same amount of brake caliper piston force.
Service and maintenance[edit]
"600 m ahead, a 38-km long continuous descent starts. Please check your brakes and add brake cooling water!" A warning sign on a highway in Yunnan, where it drops ca. 1,500 m over a 38 km distance. Water is sprayed or dripped on brake drums for cooling.
Most automotive professionals agree that glycol-based brake fluid, (DOT 3, DOT 4, DOT 5.1) should be flushed, or changed, every 1–2 years under non-racing conditions.[9] Many manufacturers also require periodic fluid changes to ensure reliability and safety. Once installed, moisture diffuses into the fluid through brake hoses and rubber seals and, eventually, the fluid will have to be replaced when the water content becomes too high. Electronic testers and test strips are commercially available to measure moisture content, however moisture test strips were taken off the market because they absorb moisture in the air before they can be used. The corrosion inhibitors also degrade over time. Degraded inhibitors cause corrosion in the braking system. The first metal to corrode is copper. You can determine when it is time to replace brake fluid when copper ions hit 200ppm.[10] New fluid should always be stored in a sealed container to avoid moisture intrusion.
DOT 5 is silicone fluid and the above does not apply. Ideally, silicone fluid should be used only to fill non-ABS systems that have not been previously filled with glycol based fluid. Any system that has used glycol-based fluid will contain moisture; glycol fluid disperses the moisture throughout the system and contains corrosion inhibitors. Silicone fluid does not allow moisture to enter the system, but does not disperse any that is already there, either. A system filled from dry with silicone fluid does not require the fluid to be changed at intervals, only when the system has been disturbed for a component repair or renewal. The United States armed forces have standardised on silicone brake fluid since the 1990s. Silicone fluid is used extensively in cold climates, particularly in Russia and Finland.
A small drop in brake fluid level in the master cylinder reservoir can be "topped up" but if the level consistently drops, the cause should be investigated and repaired. Brake fluid level in the master cylinder will drop as the linings (pads or shoes) wear and the calipers or wheel cylinders extend further to compensate. Overspill from pushing back pistons should be avoided, because glycol based fluid will quickly lift or strip paints and other coatings on contact (it can be removed by quickly washing with water, not wiping). Brake fluid level may also be low because of a leak, which could result in a loss of hydraulic pressure and consequently a significant loss of braking ability. Modern cars have redundant hydraulic circuits (two separate circuits) to ensure against total hydraulic failure.
Brake fluids with different DOT ratings can not always be mixed. It must be of the same type, and at least the same rating. DOT 5.1 can replace DOT 4 and 3, DOT 4 can replace DOT 3. DOT 5 should not be mixed with any of these as mixing of glycol with silicone fluid may cause corrosion because of trapped moisture.
Brake fluid is toxic and combustible[11] and can damage painted surfaces.[12]
Components[edit]
Castor oil-based (pre-DOT, DOT 2)[edit]
Castor oil
Alcohol, usually butanol (red / crimson fluid) or ethanol (yellow fluid) (metanol)
Glycol-based (DOT 3, 4, 5.1)[edit]
Alkyl ester
Aliphatic amine
Diethylene glycol
Diethylene glycol monoethyl ether
Diethylene glycol monomethyl ether
Dimethyl dipropylene glycol
Polyethylene glycol monobutyl ether
Polyethylene glycol monomethyl ether
Polyethylene oxide
Triethylene glycol monobutyl ether
Triethylene glycol monoethyl ether
Triethylene glycol monomethyl ether
Silicone-based (DOT 5)[edit]
Di-2-ethylhexyl sebacate
Dimethyl polysiloxane
Tributyl phosphate
See also[edit]
Brake bleeding
Disc brake
Drum brake
Hydropneumatic
Pascal's law
References[edit]
Jump up ^ http://www.peterverdone.com/archive/files/hydraulic%20system%20theory.pdf
Jump up ^ http://www.epicbleedsolutions.com/blog/dot-brake-fluid-vs-mineral-oil/
Jump up ^ http://www.epicbleedsolutions.com/blog/dot-brake-fluid-vs-mineral-oil/
Jump up ^ "49 CFR 571.116 - Standard No. 116; Motor vehicle brake fluids.".
Jump up ^ http://www.epicbleedsolutions.com/blog/dot-brake-fluid-vs-mineral-oil/
Jump up ^ http://www.viscopedia.com/viscosity-tables/substances/automotive-brake-fluid/
Jump up ^ http://www.epicbleedsolutions.com/blog/dot-brake-fluid-vs-mineral-oil/
Jump up ^ http://www.peterverdone.com/archive/files/hydraulic%20system%20theory.pdf
Jump up ^ Bosch Automotive Handbook Archived October 27, 2008, at the Wayback Machine., 7th Edition, ISBN 978-0-7680-1953-7
Jump up ^ [1]
Jump up ^ "MSDS for DOT 3 brake fluid" (PDF). Retrieved 2012-06-04.
Jump up ^ [2]
External links[edit]
Car care council
How Stuff Works: What are the different types of brake fluid?
StopTech: Brake Fluid 1A
http://www.motorist.org/articles/auto-braking-systems
[show]
v
t
e
Motor fuels
Fuel types
Gasoline/petrol
Diesel
Biodiesel
Lead Replacement Petrol
Kerosene
Compressed natural gas
Hydrogen
Ethanol
Butanol fuel
Racing fuel (Tetraethyllead)
Fuel additives
Butyl rubber
Butylated hydroxytoluene
1,2-Dibromoethane
1,2-Dichloroethane
Dimethyl methylphosphonate
2,4-Dimethyl-6-tert-butylphenol
Dinonylnaphthylsulfonic acid
2,6-Di-tert-butylphenol
Ecalene
Ethylenediamine
Metal deactivator
Methyl tert-butyl ether
Nitromethane
Tetraethyllead
Tetranitromethane
Fluids
Motor oil
Antifreeze
Automatic transmission fluid
Brake fluid
Gear oil
Windshield washer fluid
Retail
Fuel card
Full service
MTBE controversy
Pay at the pump
[show]
v
t
e
Powertrain
Part of the Automobile series
Automotive engine
Diesel engine
Electric
Fuel cell
Hybrid (Plug-in hybrid)
Internal combustion engine
Petrol engine
Steam engine
Transmission
Automatic transmission
Chain drive
Clutch
Constant-velocity joint
Continuously variable transmission
Coupling
Differential
Direct-shift gearbox
Drive shaft
Dual-clutch transmission
Drive wheel
Electrohydraulic manual transmission
Electrorheological clutch
Epicyclic gearing
Fluid coupling
Friction drive
Gear stick
Giubo
Hotchkiss drive
Limited-slip differential
Locking differential
Manual transmission
Manumatic
Parking pawl
Park by wire
Preselector gearbox
Semi-automatic transmission
Shift by wire
Torque converter
Transaxle
Transmission control unit
Universal joint
Wheels and Tires
Wheel hub assembly
Wheel
Rim
Alloy wheel
Hubcap
Tire
Tubeless
Radial
Rain
Snow
Racing slick
Off-road
Run-flat
Spare
Hybrid
Electric motor
Hybrid vehicle drivetrain
Electric generator
Alternator
Portal
Category
Retrieved from "https://en.wikipedia.org/w/index.php?title=Brake_fluid&oldid=793388655"
Categories:
Vehicle braking technologies
Automotive chemicals
Hydraulics
Hidden categories:
Webarchive template wayback links
All articles with unsourced statements
Articles with unsourced statements from May 2015
All articles with failed verification
Articles with failed verification from November 2015
Navigation menu
Personal tools
Not logged in
Talk
Contributions
Create account
Log in
Namespaces
Article
Talk
Variants
Views
Read
Edit
View history
More
Search
Navigation
Main page
Contents
Featured content
Current events
Random article
Donate to Wikipedia
Wikipedia store
Interaction
Help
About Wikipedia
Community portal
Recent changes
Contact page
Tools
What links here
Related changes
Upload file
Special pages
Permanent link
Page information
Wikidata item
Cite this page
Print/export
Create a book
Download as PDF
Printable version
Languages
Čeština
Deutsch
Eesti
Ελληνικά
Español
فارسی
Français
Հայերեն
Italiano
Magyar
Nederlands
日本語
Polski
Português
Slovenčina
Suomi
Svenska
ไทย
中文
Edit links
This page was last edited on 1 August 2017, at 12:37.
Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.
Privacy policy
About Wikipedia
Disclaimers
Contact Wikipedia
Developers
Cookie statement
Mobile view

key: html

type: local

value: div

attrs: id class

values: mw-page-base noprint

values: mw-head-base noprint

attrs: id class style

value: a

attrs: id class lang

values: firstHeading firstHeading en

values: siteSub noprint

values: jump-to-nav mw-jump

value: b

attrs: href title

attrs: href class title

values: /wiki/Automobile mw-redirect Automobile

values:
/wiki/Pascals_law#Explanation
mw-redirect
Pascals law

values:
/wiki/Compression_(physical)
mw-redirect
Compression (physical)

value: p

values:
/wiki/Society_of_Automotive_Engineers
mw-redirect
Society of Automotive Engineers

values:
/wiki/Department_of_Transportation
mw-redirect
Department of Transportation

values: This claim needs references to reliable sources. (May 2015)

values:
noprint Inline-Template Template-Fact
white-space:nowrap;

values: The material near this tag failed verification of its source citation(s). (November 2015)

attrs: alt src width height class srcset data-file-width data-file-height

values: Edit section: Castor oil-based (pre-DOT, DOT 2)

values: Edit section: Glycol-based (DOT 3, 4, 5.1)

values:
/wiki/Diethylene_glycol_monoethyl_ether
mw-redirect
Diethylene glycol monoethyl ether

values: Dimethyl dipropylene glycol (page does not exist)

values: Polyethylene glycol monobutyl ether (page does not exist)

values: Polyethylene glycol monomethyl ether (page does not exist)

values:
/wiki/Polyethylene_oxide
mw-redirect
Polyethylene oxide

values: Triethylene glycol monobutyl ether (page does not exist)

values: Triethylene glycol monoethyl ether (page does not exist)

values: Triethylene glycol monomethyl ether (page does not exist)

values:
/wiki/Dimethyl_polysiloxane
mw-redirect
Dimethyl polysiloxane

values:
/wiki/Lead_Replacement_Petrol
mw-redirect
Lead Replacement Petrol

values: nowraplinks collapsible autocollapse navbox-inner

attrs: alt src title width height srcset data-file-width data-file-height

values:
navbox-abovebelow hlist
2
font-weight:bold;

values: navigation navbox Powertrain padding:3px

values: Category:Webarchive template wayback links

values: Category:All articles with unsourced statements

values: Category:Articles with unsourced statements from May 2015

values: Category:All articles with failed verification

values: Category:Articles with failed verification from November 2015

values: Discussion about edits from this IP address [ctrl-alt-n]

values: A list of edits made from this IP address [ctrl-alt-y]

values: You are encouraged to create an account and log in; however, it is not mandatory

values: You're encouraged to log in; however, it's not mandatory. [ctrl-alt-o]

values:
/wiki/Brake_fluid
View the content page [ctrl-alt-c]
c

values: Discussion about the content page [ctrl-alt-t]

values: p-namespaces navigation vectorTabs p-namespaces-label

values:
p-variants
navigation
vectorMenu emptyPortlet
p-variants-label

values: Past revisions of this page [ctrl-alt-h]

values: p-views navigation vectorTabs p-views-label

values:
p-cactions
navigation
vectorMenu emptyPortlet
p-cactions-label

values:
mw-wiki-logo
/wiki/Main_Page
Visit the main page

values:
/wiki/Main_Page
Visit the main page [ctrl-alt-z]
z

values: Featured content – the best of Wikipedia

values: Find background information on current events

values:
/wiki/Special:Random
Load a random article [ctrl-alt-x]
x

values: portal navigation p-navigation p-navigation-label

values: Guidance on how to use and edit Wikipedia

values: About the project, what you can do, where to find things

values: A list of recent changes in the wiki [ctrl-alt-r]

values: portal navigation p-interaction p-interaction-label

values: List of all English Wikipedia pages containing links to this page [ctrl-alt-j]

values: Recent changes in pages linked from this page [ctrl-alt-k]

values:
/wiki/Wikipedia:File_Upload_Wizard
Upload files [ctrl-alt-u]
u

values: A list of all special pages [ctrl-alt-q]

values: Permanent link to this revision of the page

values: Link to connected data repository item [ctrl-alt-g]

values: Printable version of this page [ctrl-alt-p]

values:
uls-settings-trigger
Language settings
0
button
true

values: Υγρά φρένων – Greek

values: روغن ترمز – Persian

values: Արգելակային հեղուկ – Armenian

values: ブレーキフルード – Japanese

values: น้ำมันเบรค – Thai

values:
suggestions
display: none; font-size: 13px;

values: mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject page-Brake_fluid rootpage-Brake_fluid vector-nav-directionality skin-vector action-view