How do you know when you need to define additional classes in your code?

[gracelimshiern]

when you have an additional set of data with a specific structure and you want to perform specific methods on it that the other current classes do not have

[shotnothing]

I think additional classes are appropriate when it makes physical/logical sense to do so. For example, not all loaders are recycled loaders, so it doesn't make sense for normal loaders to have recycled loader specific code inside. From a physical perspective, a normal loader would not know what a recycled loader is, nor how much time it would take for maintenance.

Another reason would be if it makes your life easier when programming, e.g. if you were making a utility library or implementing a comparator class.