Hugo at aruncoaches.co.uk
Tue Nov 14 19:08:23 EST 2017
### Caterpillars. Yes, I rebuilt a 3406E (in a Kenworth W900B) a few years
ago in my back yard. I bought it with a porous liner & fitted pistons,
liners & bearing shells. Ran very nicely but it wasn't much fun moving all
that heavy machinery over grass - especially the head! I run Cummins L10 in
my buses - best engine in the world! I bought my first one in 1992 when it
had 800,000 miles on it. I am still running that coach without ever touching
the engine! Even the injectors and turbo are all original. Runs as sweet
today as the day I bought it. Must have 2 million miles at least by now. I
love Cummins - smoother (and more economical) than Cat.
Anyway I'm rambling! I think the Corvair fan might benefit from some sort of
viscous drive - just something to take up the shock and allow the load to be
applied more gradually to the belt. But at the end of the day, are we trying
to solve a problem that doesn't really exist? I haven't had my Corvair very
long, but are the fan belts really a problem? I know they look weird, going
round a corner like that, but they seem to work ok, and you can keep driving
without one for a bit. Doesn't the manual say something like drive for ten
minutes then let it cool down? Should get you home (eventually!). And modern
belts are better than the ones they were designed for.
Going back to the original post, the idea of a more efficient fan is
excellent, now that we probably understand these things better than they did
in the 50's & 60's, as long as it can be made light enough. I would
certainly be in the market for one if the idea reaches production. I
suggested in an earlier post maybe fitting a larger pulley to the fan if you
can make it more efficient - that would lessen the load.
From: James P. Rice via VirtualVairs
Sent: Tuesday, November 14, 2017 10:26 PM
To: virtualvairs at corvair.org
Hugo: I'm retired from Caterpillar, which uses a lot of hydraulics on all
the products. Back in the mid to late 1980's I had the same idea about
driving the Corvair fan hydraulically. So, since I had access to the
Similar Parts books, I went looking at what Cat had/use in the way of
Hydraulic pumps. They had several modest size pumps, but size and weight
were the issue. And you still have to have a belt to drive the pump, which
would still be subject to the shock of rpm changes on downshifts. Without
the two bends in the belt drive, it might work, buy the size and weight is
still an issue. The routing of the hoses from pump to the top of the fan is
also an issue.
Another idea is to use a hi psi/hi flow oil pump and figure out how to bleed
off some of the oil flow to spray against or into a pump drive under the top
engine cover. A turbine impeller mated to the rotating vertical shaft with
the fan pulley bolted to the top of the shaft. Or use a second oil pump
similar to a dry sump set up. (Bill Thomas ran a dry sump on his Corvair
race car at one point back in the early 60's, so a second external pump is
doable) and route the oil under/into the pump or some other drive set up
inside the top engine cover, Draining the oil back into the crankcase may
be a issue. Or getting it back to the second external pump. Maybe some
internal duct work to do to get the oil so it doesn't hit the crankshaft or
rods as the whirl away? Not all that hard to conceptualize, maybe difficult
to impossible to engineer...! VBG!!!
Don't stay awake thinking about it. But imagine the looks on the faces of
bystanders as the fan turns without a visible drive system!
Vertical fan is thus far the best way to solve the problem if you are doing
serious high rpm downshifts like the racers do.
Isn't it fun to try and figure out how to solve the problems we create when
we use our Corvairs for anything other than their intended use as grocery
getters or 2nd car to drive to work in?!
Date: Tue, 14 Nov 2017 09:07:04 -0000
From: "Hugo Miller" <Hugo at aruncoaches.co.uk>
To: "kevin nash" <wrokit at hotmail.com>, <jimster1 at earthlink.net>,
<virtualvairs at corvair.org>
Subject: Re: <VV> My new experimental fan
I operate a small coach company in the UK, and my coaches have the
radiator on the left side at the back, away from the engine, with a neat
hydraulic fan drive. Very simple and works really well, with the added
advantage that it can be thermostatically controlled. I've often wondered
whether this system could be applied to the Corvair?
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