Traveling Irrigator drive motor

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

Reply to
Karl Townsend
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Hi, Karl. I'm guessing this is a good fit for a 24 volt motor and a solar charging set up. A guy in Northern CA makes and sells something similar. He has us build a circuit board for us. I will try to get the name, etc. for you when my GM gets back from a delivery run to another customer.

Paul in Redmond, OR

Reply to
co_farmer

Ok, here is the company:

Motive Engineering (530) 468-5374

They are in Ft. Jones, Ca.

See if they have anything to offer for your irrigation problem.

Paul

Reply to
co_farmer

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

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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

Reply to
woodworker88

I don't know this for certain, but would be willing to wager that the pressure loss is due more to lost flow through the turbine nozzle than to lost "pressure". More'n likely, the oriface isn't large enough to swamp the flow requirements of your spray nozzle. All this, IF it's a "full flow" system, with the turbine in series with the sprinkler nozzle.

If that's all the case, then you might consider putting it in parallel, and running a small "secondary" spray nozzle to exhaust the portion of water the turbine uses.

I've always been on a well (residential), and have had nothing but bad luck with water-motor drives at the pitifully low cut-in pressure on most well pumps. They tend to stall when the water pressure starts to get low, and don't start to spin again (if ever) until the pressure peaks again.

LLoyd

Reply to
Lloyd E. Sponenburgh

Could you just increase the supply pressure, so the gun still gets 115 psi after the turbine?

Bob

Reply to
Bob Engelhardt

This makes sence. I'm going to measure the torque here with a torque wrench. It is possible, but hard, to reel in the hose here with a hand crank. Its in the area of 80 to 100 ft lbs.

I'm willing to experiment, but I want to start with a knowledgeable best estimate for motor and power supply.

karl

Reply to
Karl Townsend

Thanks, I'll give them a call.

Karl

Reply to
Karl Townsend

I would suspect that the nozzle of your gun is worn and because of that requires the higher water pressure to work properly. The same thing happens with my pressure washer when the nozzle is worn.

John

Reply to
john

10 ft-lbf at 500 RPM is about 709 watts or 0.952 HP. Figure about 50% efficiency as a SWAG for motor + gears, so maybe 1500 watts of electricity. That's 125 amps at 12 volts or 62.5 amps at 24 volts. That's a lot for continuous drain from reasonably-sized deep-cycle batteries, but it is definitely within reach of reliable, long-lived DC motors. Some trolling motors can do this and they last for years. They're intrinsically water-cooled, being immersed while in service. I'd have to check, but I think their speed (with no gears) is in the right ballpark too.

You sure about the 10 lbf-ft from the turbine? That seems like a lot but I have no experience with irrigation systems.

Reply to
Don Foreman

You hit the nail on the head here. I must go out a minimum of 1/hour 24 hours a day to check the unit. Problem 1 is turbine stalling. I'm running it as slow as it will go to put down more water - below its rated range. A system that works well would let me sleep at night.

Karl

Reply to
Karl Townsend

Pure guess, and on the high side. I plan on measuring force to pull the hose at the PTO/hand crank shaft. And the exact gear reduction the system has today. Makes sense to not re-use the existing gear reduction setup. Then I could look for a DC gear motor. This should be way more efficient.

The traveler is close to the reel today. I'll measure tomorrow when a full length of hose is out. The place I'll set it out is also an uphill lie, so I can get max. force. I'll just have a static torque wench number, moving force will be lower.

Karl

Reply to
Karl Townsend

What is your flow rate in gallons per minute, Karl?

Reply to
Don Foreman

Hi Karl,

How about a few pictures of your current rig while you're taking measurements. You know how everyone likes to look, comment, comment, argue after a few pictures :)

Seriously I think you will get some better ideas to kick around if we can see the actual device/problem...

Reply to
Leon Fisk

Have you considered switching to pod irrigation?

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Wayne

Reply to
wmbjkREMOVE

That would have trouble getting over a ten foot apple tree.

Karl

Reply to
Karl Townsend

150 GPM at 120 PSI - well head. Only losing 5 PSI to line riser. That dang turbine was/is taking 15 PSI. These numbers go up/down 10 psi depending on elevation, takes 1 psi for every two feet.

I have all the part numbers lined up for this pump failing. Its getting worn out. The next pump will do 200 GPM at 120 PSI. If you'd care to donate $9K to the apple farmer's relief fund, I'll install it next week.

Karl

Reply to
Karl Townsend

Why do you think so? One way or another, the motor speed must be matched to the load speed regardless of who sold the gears. Some gear trains are more efficient than others, though. For high reductions, worm gears tend to be more efficient than trains of spur gears because it takes fewer gears to achieve the same ratio.

I know that Lorenz Mfg. in Benson uses some Boston worm gear drives, don't know if they'd sell ya one or not. They make electric winches among other things. Also farm machinery.

Might be helpful to know the ratio (if any) between PTO/handcrank and hose reel, or (perhaps better) what rev rate of PTO/crank results in hose retreival of 50 ft/hr.

Reply to
Don Foreman

I can do one better. Its an Ag-rain T23A. Here's the parts manual:

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Backup to the main web page for an overall view.

Karl

Reply to
Karl Townsend

I doubt it. It still takes a lot of power to pull in the hose- have you ever cranked one by hand? I have.We sell lots of travelers and I've never heard of a turbine bearing failure (We used to sell Kifco and switched to Micro Rain a year ago). FWIW- your 15 psi pressure drop is caused not only by the turbine, but also the drag in the rest of the water circuit ( there is a lot of loss in all that hose) and attempting to go above a water velocity of about 5 fps by boosting pressure ( you can't boost flow) only makes things worse by introducing turbulence in the system.

Why not rebuild the turbine and be done with it? It'll be super reliable and run more than 120 hours a week no worries.

-Carl

Reply to
Carl Byrns

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