OK. I'm at it again. ( waiting for the mud to dry on my plug mold.)
Here's a little sketch of a means to move the rudders without using a
hydraulic pump. I checked out some off-the-shelf hydraulic cylinders and with
a little modification, they can be adapted to operate as a master/slave
combination.
I would need to drill out the orifices so the oil flow wouldn't be so
restricted, because the pressure is less than a system using a pump.
By pushing the left pedal ( master cylinder ), oil is pushed into
the left slave cylinder and moves the rudder linkage left. With the two slave
cylinders linked as opposing systems, this will depress the right slave
cylinder, pushing that oil back into the right master cylinder. When a right
turn is required, the opposite (right ) pedal is pushed and the oil pushes
back into the left slave/master system, making the rudders turn right.
With the addition of a pressurized oil reservoir ( via scuba tank ) and
check valves, the entire system would be pressurized to just above ambient, so
water wouldn't enter the system.
Although the system is pressurized to prevent incursion of water, the
pressure between left and right is essentially the same. As you push a pedal,
you're applying force against the rudder linkage, but not against the
internal system pressure. ( merely a transfer of oil into one and out of the
other ) There's going to be some additional resistance from friction in
the lines, but with the correct orifice size, that should be
minimal.
With the pressurized reservoir, any leakage of oil past the seals will be
made up by the reservoir.
Now, a spring loaded centering linkage at the rudder linkage would return
the rudders to center if no pedals are pushed, so when a pedal is pushed, that
force would need to be overcome, but it wouldn't take a very big spring to
bring the rudders back to center because the system pressure ( scuba
tank supplied ) is equal on each side. With a slow steady push on a
pedal, it would move the rudder slowly, or with a hard STOMP it could move
more quickly. Let off on both pedals and the spring would return the
rudders to center. This could also be made to operate with a steering wheel
and rack-and-pinion set-up at the master cylinder end. With the right gearing,
it could be possible to make steering easier than with pedals that would
require direct pressure against the rudders PLUS the spring pressure, although
it would take more travel ( turns on the wheel ) than just the short stroke of
each pedal.
Any body got thoughts on this hair brained idea ? Frank D.