August 31, 2015-Hydraulic Pains
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Cylinder on the workbench
On the race course it is important to “keep your head out of the boat”, meaning to look around and see the big picture. Being able to see past the trees and notice the forest can be helpful in boat maintenance too.
A couple of days ago I installed some new gauges for hydraulic system. To make sure the new gauges worked I pumped up the system. The gauges looked fine but I spotted a leak in the backstay cylinder.
OK, change the cylinder; that’s why I have a spare (head in the weeds).
The spare leaked too. Damn (head still in the weeds).
I took the leaking cylinder down to the workbench, rebuilt it, and then put it back in place (I still had my head down in the weeds).
The rebuilt cylinder briefly held pressure but then it spouted fluid like a sprinkler.
Finally it dawned on me that something bigger was going on here.
Let’s see... We keep an online record of all of our equipment failures and maintenance projects so I did a search to see when that backstay cylinder was last worked on. (Actually this record is on the Internet on our Log Book Pages site, so it is very accessible. You can review these records too, if you want to. Just click on this
link and scroll all the way down the index on the right side, it's extensive.)
I was astonished to find out that the backstay cylinder had failed 10 times in the last 15 years! That was a pattern I had not recognized. In fact I didn’t remember most of the occurrences until I saw them spelled out in black and white.
It was time to take a step back and figure out what is happening to these cylinders instead of simply fixing them each time they blew up.
With three failures in two days I had a good sampling of broken parts on my workbench to examine. I quickly found that in every case the initial point of failure had been the rod seal. No other parts seemed to be damaged except by my subsequent removal. The rod seals were all from the same batch I bought in Hong Kong in 2004, right about when the backstay failures started to become frequent. I took a look at these little green bits of plastic. They looked so nice, and I had been so proud to score them in that little hydraulic shop in Mongkok back in 2004. But even the one I just put in yesterday seemed soft and the broken bits in my hand were crumbly. No wonder the cylinders were failing; the rod seals were disintegrating.
After some internet research on rod seals I headed off to my new favorite hydraulics shop in Las Juntas, near Puerto Vallarta, where Rosalia helped me find the nearest replacement part she had. There were two of them and they looked good, a lot more substantial than the ones I got in Hong Kong. I took the two she had and ordered four more from Guadalajara. Just for safety sake I went online and ordered another four from the Seal Shop in Portland, for a total of 10. (Well, I have five of these -12 size cylinders on Wings, I might as well have enough parts for all of them.)
With my new seals in hand I was back in the workshop rebuilding the backstay cylinder one more time. It wasn’t easy. The new seals were tough and they resisted being stretched into place, plus they were a little too tall and I had to carve them down a bit, but finally I got one cylinder completely refurbished and installed. I put 3500lbs on it. It worked. No Leaks. I then rebuilt the spare and, confident now in my work; and put it in the spare locker in case we need it in the future. That’s five rebuilds I’ve done in four days. Judy thinks that’s my new life: standing at the workbench all day rebuilding hydraulic cylinders.
But that’s all behind me now. Since I have now seen the big picture I’ve been able to solve the underlying problem. I don’t think we’ll have backstay failures for a while, or I hope not anyhow.
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Now if I could only apply that principle to our racing strategy.
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Fred & Judy, SV Wings, La Cruz Huanacaxtle.