Stirling Engine with Ross yoke
Andy Ross, a prominent Stirling engine experimenter, developed a Stirling engine using the linkage illustrated here. This engine is identical in operation to the two cylinder Stirling. In this illustration, the left cylinder is the hot cylinder.
The linkage allows the engine to be more compact, and reduces side loads on the pistons and connecting rods (because their travel is almost linear).
Note on the linkage
In an earlier version of this page, I stated that Andy Ross invented this linkage, and cited Rizzo3 as my source. However, I’ve since discovered linkages very much like this one on other engines that appear to predate Ross: the Musgrave engine circa 1843,10 and the Bernay engine circa 1878,11 are examples; both are steam engines.
I suspect it is probably incorrect to say that Mr. Ross invented the linkage. Perhaps he was the first to use this linkage in a Stirling engine, or perhaps he developed this particular geometry that had not been previously used. Rizzo3 does not give further details.