I've recently purchased a 500# pull linaer actuater to operate a valve on
an aggregate spreader we are building. I think your idea has merit but seems
overcomplicated to me. I think you may be thinking this way because as you once
said you are not a machinest. I plan to use single hydraulic cylinders because
they are tidy. A small 1 inch cylinder with a 1/2 inch rod will have .196 square
inches of surface area at the rod end. At 200 feet this translates to less than
20 pounds of force. At just 500 psi the one inch diameter cylinder will generate
392 pounds of force.To overcome the one way seal at the end of the cylinder I
plan on removing and replacing the end cap with one I machine to accept an inner
seal with lips facing in and an outer seal with lips facing out. This should
solve the water intrusion issue. Just my two cents!
----- Original Message -----
Sent: Saturday, October 11, 2008 1:32
PM
Subject: Re: [PSUBS-MAILIST] Re: Thank
you Phil !
Here's what I've been doing with the method Phil explained for the
manipulator arm power.
The method of using an off-the-shelf linear actuator to drive a "master
cylinder" which in turn activates an external "slave cylinder" is what
I've been working on for my rudders and dive planes. With double acting ( suck
and blow ) cylinders, the ambient pressure isn't trying to force the piston in
either direction. Sufficient pressure to maintain a seal, keeping water out of
the system, must be maintained either by a pump or possibly an oil reserve
tank with an air space that's pressurized by a line from the high pressure
manifold on the sub. This reserve tank must be strong enough to withstand the
external ambient pressure, plus a little extra so the hydraulic pressure in
the system keeps the water out. The whole system is able to be isolated from
the sub interior with valves at all hull penetrations, and tank connections. I
wonder how well a water based system would work like Phil mentioned.
The electric actuators I've found so far run about $100 or so
each, and small hydraulic cylinders can be had for about $80 on ebay. For my
rudder/dive plane set up, I need three electric actuators, three master,
and three slave cylinders. The K boats use manual levers for dive plane
and rudder control. Definitely much cheaper. Frank
D.