I also got to spend some real time on a wringer crank in my youth. A more modern design to be sure, that was permanently mounted on a pivot that was attached to the tub type washing machine, such that it could be swung out over the sink to use, or swung back out of the way when not in use.
Not really well suited to steam power in my opinion, unless it is intended to just run free. Otherwise a very powerful steam engine with large flywheel would need to be used, as just a fold or two of wet cloth going through would more than triple the load on the crank, and would easily stall out one of our little steam engines. I'd also advise that if it is powered up to the level of fully operational under steam power, then it would pose a serious risk to a careless user.
Cool find Jan ... it would go well with the washboards we have gracing our laundry walls!
Are we having fun yet?