On Jul 23, 7:52 am, "Karl Townsend"
wrote:
I burned the bearings out on my drive turbine for the traveling irrigator.
To get by, I removed the turbine completely and I'm pulling hose in with the
tractor PTO.

I LEARNED SOMETHING! The turbine takes its power out of the water pressure.
Its reducing pressure to the sprinkler from 115 PSI to 100 PSI. And the gun
works WAY better at the higher pressure.

The power from the turbine is dinky. You twist it by hand to start it when
it stalls. I'm going to guess 10 ft lbs. It runs at maybe 500 RPM. There's
then a gear train that reduces the speed by maybe 500:1 to give high torque
to the bull gear driving the reel. This assembly pulls in a 3" water hose at
50 feet per hour.

I'm wondering if a DC motor and deep cycle batteries would do this job. This
thing needs to be super reliable, it runs more than 120 hours a week. Am I
within the power range of a DC motor setup? I'd need at least 8 run hours
between recharging. What would be the best unit in terms of efficiency?

FWIW, I could lay a 110 volt wire in the fence line where the traveler hooks
up. Line loss would be terrible because it would be over 1/4 mile long. But
maybe it could run a 12 volt charger. I couldn't get to all the spots this
way.

I won't be trying this in the middle of this drought. I'd build it this
winter.

Karl

Deep cycle batteries would probably work. Ideally you'd have a bank
of batteries, and you'd either draw from all simultaneously, or have
circuitry to monitor the voltages and switch from an old battery to a
fresh one as the voltage drops. Either experimental testing (which
i'm inclined to) or an electrical engineer would tell you which is the
most economical/reliable solution. Then you could charge the
batteries when not running. In terms of gear motors, take a look at
Surplus Center for good DC gearmotors (www.surpluscenter.com). My
inclination would be this: a 500:1 reduction, particularly when we're
talking farm equipment and not precision electronics or something,
isn't going to be all that efficient. Maybe I'm wrong, but I would
tend to buy an off the shelf gearmotor (which is a motor already
fitted to a nice reduction) to get the same rpm and power, and then
bypass the existing gear train all the way to the bull gear. My guess
is that you could switch from 10 ft-lbs to 50 or 100 ftlbs and need
only a small reduction, maybe 10:1 or so. I'd bet the power
consumption would go way down.
ww88