Does not this remind you of the mechanics drawn by James Watt ? But it's necessary to back 250 years back ..
Hand-drawn diagram by James Watt explaining his discovery of the "parallel motion" in a letter to his Sohn: "The idea originated in this manner. On finding double chains, or racks and sectors, very inconvenient for communicating the motion of the piston-rod to the angulat motion of the working-beam, I set to work to try if I could not contrieve some means of performing the same form motions turning upon centres, and after some time it occured to me that AB, CD, being two equal radii revolving on the centres B and C, and connected together by a rod AD, in moving through arches of certain length, the variations from straight line would be nearly equal and opposite, and that the point E would describe a line nearly straight, and that if for convenice the radius CD was only half of AB, by moving the point E nearer to D, the same would take place; and from this the construction, afterwards called the parallel motion was derived."
Of course, instead of a rope, you can use any type of parallel movement mechanism.
And of course, it's getting higher and higher speed after that ...
So this Wats is not bad anymore .. but this string can have such a form of springs from the watch's bannister .. and then it is the simplest solution and guaranteeing higher revolutions .. obviously the ideal is Peaucellier-Lipkin, but also is the most complicated .. But after some analysis, to which the arms attach to the connecting rod, i.e. which carries the main forces, the rest may not have to be a monstrous size ..
In any case, the use of a traditional crosshead certainly became archaism ... because with the use of any of these solutions, the side force on the crowd does not occur, and was not moved below, to crosshedas, and was liquidated at all ..
Also from my drawing you can see that a very easy way we can do cooling with the water of the piston ..
This can give us, due to its very low temperature, a change to Teflon efflorescence and one would be tempted to completely give up the oil.
And this is a very important matter, which allows us this construction, so it seems to me that maybe you can do practically this matter and try some teflon bearings and seals
https://en.wikipedia.org/wiki/Peaucelli ... in_linkage
Here is the animation of THE PEAUCELLIER-LIPKIN LINKAGE which is automatically downloaded
Normal position engine crosshead Peaucellier-Lipkin :rolleyes: