How Do Automobile "Sway Bars" Work?

[TexasBEAST]

A web search gives sales sites for sway bars, but doesn't explain them. Can someone else do so?

 

[Aoidoi]

Those would be bars with names like "The Man-Hole" ... ... oh, wait. Sorry, misread that.

 

[repairman]

Essentially they are springs that connect the wheels from side to side. As the car starts to roll side to side in a turn the bar puts more downward pressure on the suspention that is compressed and makes the car roll less

 

[ceptimus]

I think 'sway bars' are the things we call 'anti roll bars' here in the UK.

I think, in this instance, our name is more sensible and descriptive than the American version.

ceptimus.

 

[jimlintott]

They make a link between lower control arms in such a way that when one lower control arm moves upward it also moves the opposite control arm upwards. This will make the car slightly squat as opposed to rolling on center.

Here's more.

 

[69dodge]

Here is a picture of one. The horizontal part of the bar is attached with bushings to the car's frame so that it can't move up or down but it can rotate. The ends are attached to the two front wheels or the two rear wheels. If both wheels move up and down together, the whole bar simply rotates freely in its bushings and provides no resistence. But when the car leans in a turn, one wheel moves up while the other moves down (relative to the car), and the bar is forced to twist, thus reducing the amount of lean.

The purpose of anti-sway bars is not just to reduce the amount of lean in a turn, however. Changing the relative roll stiffness of the front compared to the rear can change the handling characteristics of the car. Stiffening the front tends to reduce oversteer or increase understeer; stiffening the rear tends to have the opposite effect.