This article is part of a section of the RcTek site devoted to radio controlled model car handling. As car handling is an extremely complex subject, it will be quite some time before it is finished.
This article explains only the basics about caster angles and does not go into details of how the handling of your model car is affected. This is covered in a the Caster Angle Advanced article.
Caster refers to the angle made between the centre of the lower pivot point of the axle block to the centre of the upper pivot point of a model car axle block when looking from the side of the car. Caster, like Camber, has three possible states, neutral, negative and positive. Caster can be measured in degrees, but it is fairly common for it to be referenced through other forms of measurement in model cars.
The pink arrow in the drawings below denotes the direction of travel of the model car.
The image on the right shows a front axle block which is set at an angle of 90 degrees to the ground and is therefore deemed to be in a neutral position.
This is the base line measurement from which the other two caster positions are measured from.
Shown right is a steering axle block, but the angle has been altered into a position that is referred to a negative caster.
This means the upper pivot point is in front of the lower pivot point. Negative caster is sometimes referred to as leading caster.
The image to the right shows a steering axle block in what is termed a positive caster position, where the top pivot point is further back than the lower pivot points.
Positive caster is sometimes referred to as trailing caster.
The principles behind caster are rooted in the small swivelling wheels that are sometimes fitted to furniture, although they are better known to many as the wheels used on supermarket shopping trolleys.
Caster angles are used to alter the directional stability of the wheels on your model car. Our article on the the Caster Angle Affect explains all about how and why this is.
Caster can be set/adjusted on a remote controlled model car by a few different methods depending on the design of the model car. More information about this can be found in our Adjusting Caster Angles article.
As mentioned at the beginning of this article, although the basic unit of measuring caster is the degree, model cars are commonly measured using other methods, which will be covered in a separate article.