Those loaders are a reference to "Experience" from all sorts of Roleplaying games. The term was originally shortened to EXP in the classic days up until about 1998 when it was slowly phased out across games for the more common XP term now. The name is also a joke on the Loader's function. When put together, the name says "EXPLoader".
This loader is similarly a reference to role playing games. PWR is a common statistic that you find attached to characters and stands for "Power". Thus, their name actually reads "Power Loader" which is a common machine.