R. Stirling's constant volume gear mechanism

[Tom Booth]

In the course of a discussion on the physics forum recently, I had it pointed out to me that the Stirling cycle and the Carnot cycle are not the same, specifically, the Stirling cycle includes "constant volume" heat addition.

I had always dismissed this "constant volume" business as irrelevant because it is impossible to have constant volume with a piston attached to a crankshaft. Such an "Ideal" could never be realized in practice, so why bother giving it any serious consideration?

The remark, however got me thinking, and prompted me to take a closer look at Robert Stirlings old original patent drawings:

robert_stirlings_engine_patent (1).gif (330.9 KiB) Viewed 14483 times

The mechanism resembles the gearing on some old steam locomotives, like the Walschaert Valve Gear system.

I found this video explaining the function and wonder if Stirlings rather complicated linkage system served a similar purpose.

https://youtu.be/b7NABUkyGok

Of course, the difference is Stirling was controlling the introduction of heat into the cylinder rather than steam.