The Third Spring

Interesting photo from Aintree Spring Sprint yesterday - and very nicely illustrates 'the third spring' concept in suspension design.



This one is on a Force single seater.

One of issues in cars with significant downforce is that they need springs strong enough to stop the car hitting the ground at speed when they might have 500-1000kg of downforce. This compromises grip at low speed when softer springs are needed to allow the wheels to ride the bumps. So to get around this, the concept of 'the third spring' was invented. On the car illustrated, the spring is a bump rubber and some bits of nylon, but on other cars this is often a small spring and damper unit.

If the suspension compresses on both rear wheels at the same time, as with downforce, the rocker arrangement slides backwards and brings the bump rubber into play, increasing spring rate.

If either wheel moves independently, as at lower speed to ride a bump, the rocker merely rotates rather than moving backwards to engage the bump rubber.

Simples

Ave it

Rob

 

Ingenious. Like a Watts linkage, when you see it it's so obvious you wish you'd thought of it.

 

Very informative

 

Neat explanation

One question; what are those alloy links across the top then jointed down the back for?

 

anti-roll bar