Editing Anti-roll bar (section)

==Purpose and operation==
[[File:A mildly modified 1992 Ford Explorer off road.jpg|right|thumb|upright=1.10|An [[Sports Utility Vehicle|SUV]], with anti roll bars removed, shows how much the body can roll without them]]

[[File:Caterham Roadsport building - 012 - Steering (almost), anti-roll bar - Flickr - exfordy.jpg|right|thumb|upright=1.10|Two front-wheel springs, with the wheels removed. Opposite suspension arms are connected to the central anti-roll bar assembly.]]
[[File:Alfetta front suspension antiroll.jpg|thumb|Anti-roll bar (in red) attached to a front axle. The bar must also have its two longitudinal anchor points fastened solidly to transfer forces from side to side.]]

An anti-sway or anti-roll bar is intended to reduce the lateral tilt (roll) of the vehicle on curves, sharp corners, or large bumps. Although there are many variations in design, the object is to induce a vehicle's body to remain as level as possible by forcing the opposite wheel's [[shock absorber]], spring, or suspension rod in the same direction as the one being impacted.

In a turn, a vehicle compresses its outer wheel's suspension. The anti-roll bar forces the opposite (inner) wheel's suspension to compress as well, thereby keeping the body in a more level lateral attitude. This has the additional benefit of lowering its [[center of gravity]] during a turn, increasing its stability.

[[File:Antiroll Bar.svg|thumb|One way of estimating antiroll bar stiffness: <br />
T=Vehicle track width (inches) <br />
K=Fractional lever arm ratio (movement at roll bar / movement at wheel) <br />
d=Bar diameter (inches) <br />
R=Effective arm length (inches) <br />
L=Half length of bar (inches) <br />
S=Length of lever arm (inches) <br />
Q=Stiffness (lb*in per degree)
<ref>{{cite book|last1=Staniforth|first1=Allan|title=Race and Rally Car Source Book|date=2001|publisher=G.T. Foulis & Co. 1983|isbn=1-85960-846-9|edition=Fourth}}</ref>]]

When both front and rear anti-roll bars are fitted, their combined effect can help maintain a vehicle's tendency to roll towards the general slope of the terrain.