You're right, interurben - I posted the same pic a few months ago (but couldn't find it again )
There were only two engines of that type. They were converted about 1943 from ordinary steam switchers. The aim was to save coal, since coal was very scarce in Switzerland during WW II. Each one of them saved about 300 tons of coal per year.
From the standpoint of energy conversion they were not very efficient, of course. But they were loved by the firemen: No coal to shovel! Heating up the boiler was a short affair, too - in less than an hour they were ready to go.
They ran until 1952, then they were scrapped.
I think I have one more pic of them. I'll try to locate, scan and post it when I come back from work.