Cylinderliners are finshed by EDM ( sparkerosion )
There are reciprocating toroidals , the TROPE ,the
Hipertec and the
NiamaReisser .
There are stop-and-go or cat-and-mouse toroidals, like the Russian one and the
rotoblock in fact remakes (try ? ) of the old
Granville Bradshaw. The old Bradshaw blow up in the one and only test..
There are rotary toroidals, like the Garric and the
Roundengine
TROPE engine :
![](http://image.dieselpowermag.com/f/diesel-engines/wonder-engines-anyone-know-dutch/35607852+w315+cr1+re0+ar1/engine.jpg)