Hi Burkhard,

I assume the gearbox is the reverse/reduction gear that drives the propeller
shaft.  Pressure indication from the gear can provide a measure of the
health of the gear.  You'll need to look at the operator's or service manual
for your gear to see what the normal pressure should be. My Twin Disc
MG-502's operate at about 400 psi ( 27.6 bar) but other gears may operate at
much lower pressures.

Pressure indication can be used for troubleshooting. In general, if the
pressure is significantly above the specified level this might indicate the
pressure relief valve is bad (not opening.)  If the pressure is below the
specified level in all positions(forward, neutral and reverse) this could be
an indication of a bad pump, low fluid level, or a relief valve stuck open.
If the pressure is low only when you are in forward and/or reverse this
could indicate internal leakage past the applicable hydraulic pistons that
engage the forward and/or reverse clutches. The service manual for your gear
should give specific troubleshooting directions.

Regards,

George Brooks
Nereid V
La Conner, WA,  USA

about

becker@presse.de writes:

You were supposed to smile, not be sorry. Most of us can use and have
a "Schieblehre" in our desk-drawer somewhere.... <g>

Ciao - George

There was an error in some data I posted earlier today.  The correct
operating pressure for the Twin Disc MG 502 reverse gear should be about 300
psi (20.7 bar).  The specified pressure range is from 290 psi to 340 psi.

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