<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>Found this underwater actuator.</div><div>Wouldn't dare estimate the price, but it is probably something we</div><div>could make easy enough!</div><div><a href="https://www.ultramotion.com/industries/underwater-linear-actuator/">https://www.ultramotion.com/industries/underwater-linear-actuator/</a></div><div>It is oil compensated & uses a brushless motor.</div><div>From the pictures, it has an enclosure near the rod end that has slots</div><div>in it. I am guessing there is a rubber bellows / bladder in there to keep</div><div>the inside of the actuator at ambient pressure & to expand & contract</div><div>to compensate for displaced oil as the piston moves in & out.</div><div> Of interest is that it is saying that the motors can be over-driven by</div><div>2-3 times due to the dissipation of the heat off the coils to the seawater</div><div>through the oil. A good argument for oil compensating rather than air.</div><div>Also being brushless the oil is not going to lift the brushes.</div><div>Alan</div><div><br></div><div><br><br>Sent from my iPad</div></body></html>