Not to argue, i will just leave this link to explain my concerns. 4cyl 4stro
kes are murder on gearboxes driving under damped (lightly loaded) air propel
lers with their reverse torque pulses. The site has other pages discussing a
s well fwiw.
http://www.epi-eng.com/piston_engine_technology/torsional_excitation_from_pi
ston_engines.htm
Cheers,
PeteZ :)
> On Dec 25, 2022, at 8:09 PM, Area-51 <goldsteinindustrial@gmail.com> wrote
:
>
@gmail.com>
>
> Thanks and noted Peter...
>
> After spending an entire lifetime pulling stuff apart and analysing cause a
nd effect of mechanical component failure i'm totally unconvinced on this ar
gument often presented, simply because the propeller is operating within a s
tate of constant load resistance leaving both the drive and driven gears no o
pportunity for backlash while in this state; if there was backlash occurring
that would be a serious design concern and source of vibration; at my level
of experience my ears and bum would let me know as soon as this occurs, and
neither have yet told me otherwise (not in this individual aircraft; can't s
ay the same for some other 912 units flown in)... the output shaft is also o
perating in a state of harmonic balance thanks to the fitted Balance Master.
.. the carburettor mixtures and carburettors are in perfect balance... the e
ngine is a low compression setup... there is no aspect about the power-plant
's current operational spectrum that gives any credibility to the debate... !
> If the engine is not singing then its out of tune, set at the wrong rpm fr
equency, or both... under constant load there are a limited number of factor
s that can cause gear failure - insufficient fit-for-purpose material specif
ication, sustained overheating beyond safe operating temperature range and a
llowable time of said material, sustained mechanical vibration at specific a
lternate frequencies, excessive mechanical impact of sliding contact surface
s due to backlash (there will always be an element of backlash required for c
omponent heat expansion), ingress of foreign matter such as swarf other part
icles dust sand etc.
>
> It is not expected many people in any mechanical field will share my exper
ience, and am still often left amazed but accepting at what level of damage t
he majority of human beings can achieve... could fill a text book with fiel
d stories, but thats about all I have to say on the matter today.
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=509788#509788
>
>
>
>
>
>
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