11/19/2003

Ringless Pistons and More

One upon a time, in the days of olde when engineers were bold and
management allowed them to think, they invented really neat stuff.

The following concept was in actually practice by 1900, but since it was
never published by peterson publications and is not endorsed by
Corkscrew Belloney and is very antique, it obviously has no value not
even to contemplate.

Delete Now - just an old concept follows.

Remember now that SWRI took a ringless piston on a crosshead rod and ran
it at 20,000 RPM.  Same stroke and bore as a small car engine.

Then, of course, there was the double acting piston concept found on a
large number of early diesels.  One combustion chamber above the piston
- one below.  

This was fine, but when your bore exceeded a foot and you measured your
stroke in feet - even a double acting piston engine was, politely,
impressive in size - enough to make it difficult to locate.

Then, someone thought of a tandem engine, where two pistons, each double
acting, were joined together on the same crosshead rod.

One "barrel" now contained a complete 4 cylinder 4 cycle engine where
every stroke in either direction was a firing stroke.  Every stroke was
a compression stroke so the issue of stress destruction near the top of
the exhaust stoke was a non-issue.  The joining of a simultaneous firing
stroke with a compression stroke on the same crosshead rod eliminated
the need for the crank to due anything except accept power from the
crosshead rod. The elimination of transferring the work of compression
thru a crankshaft greatly reduced the vibrations associated with an
engine and reduced the need and size of a flywheel.

Thus we have the Tandem Engine from history.

Not being good enough with the power of a 4 cylinder engine, two tandem
engines were spliced together at 90 degree intervals to make a "Dual
Tandem Engine" and we now had flat eights that were nowhere close to the
size of a vertical 8. 

Now if you check out free piston engines - one or more double acting
pistons on a crosshead rod - and an upper range of ridiculous rpm -
measured in the decades of thousands of cycle's per second, the tandem
engine is a four cycle free piston engine with a crankshaft connected at
one end.

For the truly demented, combine a dual or triple tandem engine with the
ringless concept of SWRI and get a smallish engine screaming at extreme
rpm. Its perfect for an adiabatic sleeve valve engine design. And if
your sexual fantasies include bondage, you could eliminate the bottom
rod and use a scotch yoke.

Visualize an antique, dating from the 1890's, Dual Overhead Cam 4 valve
pentroof engine - a design that by the time of the Tandem Engines was
laying in the scrap heap of expensive and bordering on useless designs -
kept alive only as a response to bureaucratic rules and stupid taxation.
You know - like a "modern" BMW or Ricer engine. Lay it on its side.  To
accommodate a crosshead piston, add the length of a stoke to the basic
size.  Say 3 inches.  Double action and crosshead is now in the block by
adding maybe 4 inches.  Eliminate the head portion of the overhead
crappola and cut the number of cylinders in half.  The double acting
cylinder is about the size of a standard ohv cylinder slice.  Now add
the tandem cylinder.  Now Eliminate the cam crapue.  And cut the number
of cylinders in half again.

The basic size without valve mechanism is about the same size as a one
cylinder slice of an overhead cam engine - except of course, if the
engine is a ford mod motor and then there is no comparison for that weak
and huge slimey POS.  Add some size for valve gear on the side of the
engine and you are done.  

Valving gets interesting.  Since the pistons are double acting, unless
you are into excess size with ancient technology, the heads have to be
"flat" and the valving on the side.  The olde phartes had no problem
with that and made efficient designs.  Above the capability of the
average enthusiast of today to understand - much less conceive - so will
be left as an exercise for the student.

Just for dreaming - picture a 16 cylinder engine about the same physical
size as an DOHC 4 cylinder engine of your choice - with 4 times its
displacement and double its rpm.