Neil Clayton wrote:

I'm trying to read everything I can on Lyc engines, since a dinosaur (an
O-360-A4A) has recently taken up residence in my workshop.

The books say that the prop thrust translates into an axial crankshaft
force, which is then transferred to the engine casing via a flange on the
forward end of the crankshaft, just behind the front bearing shells. The
flange runs against a machined face in the crankcase (amazing - no thrust
bearing at all!)

Anyway....all is OK as long as the engine is in the tractor configuration.
But in a pusher config, the prop thrust will have the effect of OPENING

the

space between the thrust flange and the crankcase thrust face.

So....my question is; how is the crank axial thrust transferred in a

pusher

config?

"Perry J. Mick" wrote:

Paul, can you clarify this, an aircraft engine
has no thrust bearings?  Nat's answer lacks any
specifics.

Nat Puffer wrote:

Neil,
Burt Rutan checked this out back in 1980 and determined that there was
no
problem with any model Lycoming in a pusher configuration, and no
problems
have been reported (to my knowledge) in the following 21 years.
Nat

Most piston engines have symmetrical oil pressure fed plain thrust bearings 
on the crank so the clearance and size between the front part  and the 
back part is the same. This is done because small forces due to minor 
machining imperfections  and the oil pressure feed itself might cause 
the crank to go one way or the other. I cannot guarantee this however  
for the O-360-A4A but I would guess it still applies.

Paul Lamar
 
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