Body Motions: Heave, Pitch, and Roll
Heave, pitch, and roll are three body motions used to describe how a vehicle moves relative to its wheels and the road.
Heave
Heave is vertical translation of the body. A road input affecting both sides together, aerodynamic load, payload, or an active suspension command can create heave without requiring body rotation.
Pitch
Pitch is rotation about the vehicle’s lateral axis. Braking commonly produces nose-down pitch and acceleration can produce the opposite response, but road profiles, aerodynamic forces, suspension geometry, and control systems also contribute.
Roll
Roll is rotation about the longitudinal axis. Lateral acceleration in a corner is a common input. Springs, anti-roll devices, roll centers, dampers, tires, mass distribution, and active systems determine the transient angle and rate.
Coupled motions
Real maneuvers combine the three. A diagonal road input can produce heave, pitch, and roll at once, while each wheel has its own bump or rebound motion. The body response depends on sprung mass and inertia, wheel rates, damping, geometry, tire forces, and control actions.
Reduced body angle does not mean load transfer has disappeared. Geometry or actuators can carry more force while limiting visible movement.
For the relationship between wheel paths, forces, and body response, see Suspension Kinematics and Vehicle Dynamics.