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Hi Frank,
I've got 2 electric linear actuators & are wondering wether I did the
right thing buying them.
At 300ft wich is my planned max operating depth there will be 78lb water
pressure on its 3/8" dia rod constantly.
I was also told people drill holes in them to aleviate pressure when the
piston goes in & out.
I'm wondering wether we can oil compensate these in a similar fashion
to a posting by Alec Smith on
" How to oil compensate a trolling motor" ( 17/06/09). Drill a hole in the
body, insert a nipple & put
flexible tube to the base that the bellows attach to & fill it all
with oil. I haven't opened mine up yet, maybe there would
be some potting involved, the small motor inside would need to be pulled
apart and filled separately.
You could also get away with a thin fiberglass enclosure.
I've got one set up on a jig with a mock up dive plane & it works
well.
Hope that made sense.
Regards Alan
----- Original Message -----
Sent: Wednesday, June 24, 2009 2:20
PM
Subject: Re: [PSUBS-MAILIST] Push Pull
Cable Rudder Control Means
I may be way off base on this, but I'm going to try and make electric
linear screw actuators control the rudders and dive planes. I found some from
"Firgelli" in the UK that should work. They have 150 pounds of push, operate
on 12 volts, and are nice and compact. The plus here is that just an
electrical thru-hull and two wires is needed for each one. No cables,
linkages, block V seals, or other possible leakers.
I'm going to use simple rocker switches to drive the actuators in and
out. They have built in limit switches and indicators, so should be able to
tell where they are. The down side is they won't "fail" in a set position like
pointing "up" for the dive planes or center for the rudders.
The idea is to encase them in a stout FRP casing molded tight to the
actuator body, and use a rubber bellows sealed with hose clamps and
poly-urethane coating for the extendable shaft.
These actuators are so compact that the aluminum body and stainless rod
don't leave much air space, so I'm hoping with a little experimentation I can
get them sealed up. Here's a pic of the actuators. They run about $100 each.
Frank D.
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