A traditional crosshead, usually unbalanced, to save a little on the construction .. But for this, when the command "whole back" is taken for the ship's engine, only 60% of the power can actually be used, because of this unsymmetrical crosshead, which can not withstand greater load, in the reverse than usual turnover.
In my solution, it does not matter which engine the engine is on, so "the whole back" can actually be "all", i.e. 100% ..
But in my solution, it may be asymmetrically, for the same reason as in the traditional one, it means that the piston is pressed down all the time, if not by the work stroke, then by the compression stroke ... (of course, it is 2 stroke ) .. Therefore, the second lower frame, can be "symbolic" and the thin line, just to keep the kinematic bond in some abnormal situations.
Of course, all this new mechanism can be in a separate housing, separating the oiled space, from the space under the piston, which can be cooled water ..
Developing further ideas for smaller engines, instead of a rope, we can use a toothed belt, whose durability is known from the mechanisms of timing ..

But the revolutions can be a little bigger ..

http://www.dtic.mil/dtic/tr/fulltext/u2/821500.pdf Here is a handbook, but it is very long uploading, because 35 MB .. On the 74 page, such a two-stroke engine, whose piston pin, is a ball, which moves only pressure from above in a pristine way ..

Andrew
