US Patent 11117436 Vehicle suspension system

A vehicle suspension system includes suspension arms mounted to a vehicle body frame to be pivotable between a low rolling posture and a high rolling posture and an anti-roll bar unit. The anti-roll bar unit includes a main anti-roll bar and a sub anti-roll bar. The sub anti-roll bar extends at least partially parallel with the main anti-roll bar. In the low rolling posture of the suspension arms, the main anti-roll bar and the sub anti-roll bar are not in contact with each other. In the high rolling posture of the suspension bars, the main anti-roll bar and the sub anti-roll bar are in contact with each other to increase stiffness of the anti-roll bar unit.