Liberator, by Richard Harland

Liberator qualifies as steam-punk literature. It's pretty good, though I suggest reading Worldshaker first. Richard Harland is an Australian author, so the third installment may be a while in coming.  Worldshaker establishes the characters and the overarching storyline: an alternate history where the major countries of the world have taken over different parts of it.  Large populations of people from England, Russia, Japan, etc., live aboard huge juggernauts that are capable of traveling by land, sea, and air.  Col Porpentine is a member of a high-class family on Worldshaker (that is the name of the British juggernaut, complete with in-residence Queen Victoria and her consort, Prince Albert).  In the first book, he meets a Filthy (one of the lowest social class-the people who keep the juggernaut running far belowdecks), a girl named Riff, who challenges everything Col has been brought up to believe.  What follows is an adventure in which Col must decide where his loyalties lie and consider true nature of the current political and social system in which he has lived his whole life.