The watermaker has been a bit troublesome.  The Duo D60 has both 230 volt AC and 24 volt DC motors that power a single CAT pump.  I removed the belt from the 230 volt AC motor so I could use a solid pulley wheel on the CAT pump.  I did this because I was having failures with the "one-way" (also called clutch bearings, sprague bearings or bendix bearings) bearings that let the idle motor free-wheel.

Now for the problem:  The water maker will run normally for 30 to 90 minutes, then it will shut itself off.  After it did this several times I watched it throughout the watermaking process and found that at first the needle in the pressure gauge was steady after adjusting to the middle of the green zone.  Shortly before it shuts itself down the needle begins to jump up and down indicating the pressure is increasing and decreasing.  The swings become more and more pronounced until it finally goes below the green zone and the automatic shutdown happens.  

I wondered if this was a low battery problem, but it doesn't seem to be.  This morning it happened at 30 minutes of run time and shut down at 24.84 volts (measured with no loads on the batteries for 5 minutes).  It also happens when I'm running the generator with a battery charger on and the watermaker on the 24 volt motor.

I'm wondering if this can be a CAT pump problem.  The hour meter only shows 680 hours and CAT pumps have the reputation of being pretty long lived.  The other symptom of the CAT pump being the problem is the propensity of those bearings to self destruct.  The ones I replaced the originals with met the same specs and yet they only lasted a dozen hours or so.  I've been told that the bearings used by Dessalator were some type of exceptionally tough bearing but the distributor disagrees with that.

Any t houghts?

Thanks in advance,

Duane

Wanderer, SM#477