Heave spring
A heave spring is a type of 3rd element that independently controls the vertical movement of an axle.
Heave is the vertical movement of an axle. The characteristic of heave is that both sides of an axle will compress at the same time. Heave of an axle occurs under aero load and during the pitch of the whole car.
How it works
As the suspension compresses, the rocker arms rotate, with each one pulling on a linkage connected to either side of a T-bar. This T-bar has 2 degrees of freedom: a single plane rotation and a pivot which results in a axis of travel. On the example image the rotation motion available is on the x-y plane and the axis of travel is parallel to the x-axis. The pivot is "under" the T bar and is in many cases a T-bar blade style anti-roll bar. The middle of the T-bar is connected to the end of a coilover which is attached to the chassis. When both sides of an axle are under compression, the rockers pull the linkages which pull the T-bar along its axis of travel. However, in order to travel along that axis the T-bar must compress the aforementioned coilover. This coilover is the heave spring. The heave spring is only active when the axle is experiencing heave. When the axle is experiencing roll, one side is compressing and the other is extending. Therefore, one linkage is pulling on the T-bar and the other is pushing. Thus, instead of compressing the heave spring, the T-bar rotates, and often twists an anti-roll bar.
Tuning
As of 2025, we do not use a heave spring.
