Daniel A. Mitchell wrote:

Crossheads were very common on LARGE Diesels since the 1930's. Even some
smaller ones had them. A few were also 'double acting' just like a steam engine.



The real reasons they need the crossheads is due to the huge stroke on this
engine, 2.58 * the bore. Most unusual on smaller engines, as they need
to fit the
engine under a vehicle hood (bonnet in the UK). It requires a very long
piston,
with the pin very low, to do a long stroke without a crosshead. Another
way to do
this is to use opposed pistons, but that is a much more complicated
arrangement
(2 cranks, etc.)

Jon