Caster

Swivel caster

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Caster-wheels-chair

Subwoofer driver and enclosure

Swivel caster with wheel lock

Caster refers to the angle of the steering pivot point in a vehicle, as seen from the side. It is a critical aspect of vehicle dynamics and suspension design, affecting the handling and stability of the vehicle.

Definition

Caster is the angle between the vertical axis of the steering system of a vehicle and the axis of the wheels, measured in the longitudinal direction. It is typically expressed in degrees. A positive caster angle means that the steering axis tilts towards the rear of the vehicle, while a negative caster angle means it tilts towards the front.

Function

The primary function of caster is to provide stability to the vehicle. A positive caster angle helps the wheels return to a straight-ahead position after a turn, enhancing straight-line stability. This is particularly important for high-speed driving, as it helps maintain control and reduces the effort required to keep the vehicle on a straight path.

Types of Caster

• Positive Caster: This is when the top of the steering axis is tilted towards the rear of the vehicle. It improves straight-line stability and steering feel but can make the steering heavier.
• Negative Caster: This is when the top of the steering axis is tilted towards the front of the vehicle. It is rarely used in modern vehicles as it can make the vehicle unstable at high speeds.

Applications

Caster is a crucial parameter in various types of vehicles, including:

• Automobiles
• Motorcycles
• Bicycles
• Aircraft landing gear

Adjustment

Caster can be adjusted in many vehicles to optimize handling characteristics. This is often done during wheel alignment procedures. The ideal caster angle can vary depending on the type of vehicle and its intended use.

Related Concepts

• Camber angle
• Toe (automotive)
• Suspension (vehicle)
• Steering

See Also

• Vehicle dynamics
• Wheel alignment
• Suspension (vehicle)
• Steering