B60G17/00—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load
B60G17/02—Spring characteristics, e.g. mechanical springs and mechanical adjusting means
B60G17/025—Spring characteristics, e.g. mechanical springs and mechanical adjusting means the mechanical spring being a torsion spring