Friday, October 5, 2012

Double Wishbone Suspensions

Lamborghini double wishbone suspension.

1.2.1 Requirements

a.  little space requirement;
b.  a kinematic and/or elastokinematic toe-in change, tending towards under-steering is
     possible.
c.  easier steerability with existing drive;
d.  low weight
e.  no mutual wheel influence.

On front independent wheel suspensions, the lateral cornering force F(Y,W,f) causes the
reaction forces F(Y.E) and F(Y,G) in the links joining the axle with the body. Moments are
generated on both the outside and the inside of the bend and these adversely affect the roll
pitch of the body.

The effective distance c between points E and G on a double wishbone
suspension should be as large as possible to achieve small forces in the body and link
bearings and to limit the deformation of the rubber elements fitted. The greater the effective
distance c between the transverse links, the smaller the forces in the suspension control arms
and their mountings become component deformation is smaller and wheel control more precise.


The wheel on the outside of the bend, which has to absorb most of the lateral force, goes into a
positive camber and the inner wheel into a negative camber, which reduces the lateral grip of
the tires. To avoid this, the kinematic change of camber needs to be adjusted to take account of
this behavior.

1.2.2 Double Wishbone Suspensions

Double wishbone consists of two transverse links (control arms) either side of the vehicle,
which are mounted to rotate on the frame, suspension sub-frame or body.


Front axle on the VW light commercial vehicle with an opposed steering square.

A cross-member serves as a sub-frame and is screwed to the frame from below.
Springs bump/rebound-travel stops, shock absorbers, and both pairs of control arms are
supported at this force center.

Only the anti-roll bar, steering gear, idler arm and tie-rods of the lower arms are fastened to the
longitudinal members of the frame.The rods have longitudinally elastic rubber bushings at the
front that absorb the dynamic rolling hardness of the radial tires and reduce lift on  uneven road
surfaces.

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