Vehicle Dynamics

A central page to host all of my posts around the subject of vehicle dynamics.

Ackermann Angle – The toe-out or toe-in of a vehicle with Ackermann steering when the wheels are positioned straight ahead.

Ackermann Deviation – The difference between the calculated ideal Ackermann angle and the actual outside wheel angle.

Ackermann steering

Ackermann Steering – A double-pivoting steering system where the outer ends of the steering arms are bent slightly inward so that when the vehicle is making a turn, the inside wheel will turn more sharply than the outer wheel.

1960s Ford Differential

Differential – Geared device between the driven wheels to allow varying rotational speeds of the wheels around corners. We see differentials in everything from the Chinese cart that has an arrow that always points south, in steam traction engines through to complex electromechanical differentials in formula one racing cars.

Gross Vehicle Weight (GVW) – The maximum loaded weight, including the vehicle itself, passengers, and cargo, for which a vehicle is designed and as specified by the manufacturer. Often used as a criterion of vehicle size for the purpose of legislation.

Independent Suspension – A suspension system that allows each wheel on a vehicle to move up and down independently of the other wheels. Allows a vehicle to provide a more level and stable ride.

Roll Axis – Longitudinal line around which a vehicle rolls (joins front and rear roll centres).

Roll Centre – Invisible moving point around which a vehicle is considered to rotate in a corner. This is the only point on the vehicle centreline that does not move up or down during a turn.

CAD image of a shock absorber

Shock Absorber – A mechanical device designed to smooth out or dampen a sudden shock impulse and dissipate kinetic energy. The shock absorber turns kinetic energy into thermal energy within the working fluids of system.

Sprung Weight – The weight supported by the suspension, including a proportion of the suspension arms.

Unladen Weight – The actual weight of a vehicle or combination with no payload.

Unsprung Weight – All parts of the vehicle that are not supported by the suspension system, wheels, tyres, brakes, etc

Wheel Hop – The vertical oscillatory movement of a wheel between the road surface and the sprung mass of the vehicle.