What characterizes a dual air brake system?

A dual air brake system is characterized by having a separate air supply for the front and rear brakes. This design enhances the overall safety and reliability of the braking system. By having two distinct air supplies, if one system were to fail, the other could still function, providing a higher level of braking performance and ensuring that the vehicle can still be brought to a stop. This separation helps in managing brake balance and reduces the risk of brake failure affecting all wheels simultaneously.

The incorrect options highlight contrasting brake system designs. A single air supply for all brakes would mean that if there was a failure in the air supply, all brakes would be affected, reducing safety. A vacuum-based brake operation refers to a different technology used in some braking systems but is not applicable in the context of air brakes. Lastly, a system that only works in good weather implies a limitation on functionality that is not characteristic of dual air brake systems, which are designed to function effectively under various conditions.