The Aerodrome Forum - View Single Post - THE HISPANO-SUIZA V-8 718 & 1127c.i. CRANKSHAFT PROBLEMS

Greybeard · 16 March 2008, 01:58 AM

Dear Mr. Anderson,

I'm unsure to have understood reason of your plethoric "raid" in this forum: I guess you're searching for confirmation the "Hisso" engines did have lubrication problems caused by vibration.

I believe possible to exclude such a phenomenon; lubrication and "shaking" are independent. Much more probable it was a cooling problem, like described by Bletchley. Oil overheating was only a consequence.

About "shaking", or vibration, as far as I know, only an in-line six cylinder can be balanced also for 2nd order ones; all remaining, like the 8V Hispano-Suiza, can be counterweighed only for 1st order forces. These latter are caused by oscillating masses of piston and about one third of rod weight, which tend, so to speak, to pull toghether the whole engine with each of them, up and down. Balancing weights on crankshaft *reduce* this forces, since they *rotate*, while those oscillate. Of course, they must be present of crankshaft, otherwise engine will retain all oscillating force caused by such moving masses. Indeed, in that era this was not yet always practiced.

GB

16 March 2008, 01:58 AM	#5 (permalink)
Greybeard Scout Pilot Join Date: Jul 2005 Location: Italy Posts: 383	Dear Mr. Anderson, I'm unsure to have understood reason of your plethoric "raid" in this forum: I guess you're searching for confirmation the "Hisso" engines did have lubrication problems caused by vibration. I believe possible to exclude such a phenomenon; lubrication and "shaking" are independent. Much more probable it was a cooling problem, like described by Bletchley. Oil overheating was only a consequence. About "shaking", or vibration, as far as I know, only an in-line six cylinder can be balanced also for 2nd order ones; all remaining, like the 8V Hispano-Suiza, can be counterweighed only for 1st order forces. These latter are caused by oscillating masses of piston and about one third of rod weight, which tend, so to speak, to pull toghether the whole engine with each of them, up and down. Balancing weights on crankshaft reduce this forces, since they rotate, while those oscillate. Of course, they must be present of crankshaft, otherwise engine will retain all oscillating force caused by such moving masses. Indeed, in that era this was not yet always practiced. GB __________________ ------------------------------------------------------ It doesn't matter what we do but in what relationship we put each other while doing what we do.