Active Member
Maybe post some screenshot on your concept? It might help other members figures what mechanism will suit u best

Also why it has hentai as tag XD
A steam engine will give a constant power output, changing the engine won't change acceleration speeds, engines are either off or on. What you need is a multi speed gearbox, which will limit the power in order to achieve lower speeds or higher speeds dependent on the gearing. I haven't made one before but they don't look too complex, I found a pretty good vid for you: