Use hydraulic motor for very slow rotation, or is there a better way?
Use hydraulic motor for very slow rotation, or is there a better way?
(OP)
Hello,
I have a bin with a unload system in that I am trying to improve. This system has two screw conveyers that go out from the center of the bin. (see photo for more detail) While these screw conveyers are spinning, I would like to power rotate them around the bin.
I have calculated that I will need approximately 400 ft-lb's of torque. The biggest problem that I see is trying to get the rotation slow enough. I only need it to rotate about once every three hours. This would put the horsepower requirements as fractional.
Would it work to use a hydraulic motor, under sufficient pressure to apply the 400 ft-lb's, or would that cause problems because it would be turning so slow? Also, if I did drive it hydraulically some way, what type of pump setup would I need for the very low flow rate?
Any help will be greatly appreciated!
I have a bin with a unload system in that I am trying to improve. This system has two screw conveyers that go out from the center of the bin. (see photo for more detail) While these screw conveyers are spinning, I would like to power rotate them around the bin.
I have calculated that I will need approximately 400 ft-lb's of torque. The biggest problem that I see is trying to get the rotation slow enough. I only need it to rotate about once every three hours. This would put the horsepower requirements as fractional.
Would it work to use a hydraulic motor, under sufficient pressure to apply the 400 ft-lb's, or would that cause problems because it would be turning so slow? Also, if I did drive it hydraulically some way, what type of pump setup would I need for the very low flow rate?
Any help will be greatly appreciated!





RE: Use hydraulic motor for very slow rotation, or is there a better way?
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist
RE: Use hydraulic motor for very slow rotation, or is there a better way?
RE: Use hydraulic motor for very slow rotation, or is there a better way?
Something that I did not mention that makes this more difficult is that all of the drive components will be under about 15' of grain. Attached is a better picture of what it looks like.
I believe installing a belt drive reduction would be nearly impossible. Grain would need to be kept out of the belts and pulleys and also the large size would carry the burden of all the grain on top of it that is displaced.
I have done a little checking into driving it with an electric motor and gear reduction but I was not able to find a gear reducer that would be slow enough and be able to handle the amount of torque that I need. Would any of you be able to steer me in right direction of what to look for? The largest reduction gear reducer that I could find was a 900:1 but we are still at almost 2 RPM which is a long way from .006 RPM. That one also could not handle anywhere near the torque that I need.
Thanks again for the help!
RE: Use hydraulic motor for very slow rotation, or is there a better way?
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist
RE: Use hydraulic motor for very slow rotation, or is there a better way?
Thank you!
RE: Use hydraulic motor for very slow rotation, or is there a better way?
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist
RE: Use hydraulic motor for very slow rotation, or is there a better way?
RE: Use hydraulic motor for very slow rotation, or is there a better way?
Are you concerned that the screws will move too fast at the bottom of the discharge ?
B.E.
You are judged not by what you know, but by what you can do.
RE: Use hydraulic motor for very slow rotation, or is there a better way?
I have spoken with a representative of the company who sold them to us and essential he told me this system was obsolete and we should scrap it. We do not want to scrap it, we just want it to work all the time. That is why I am pursing some type of positive drive system for the rotation.
Compositepro, may I ask why you say it will not work to drive it from the center under 15' of grain? After the bin has been cleaned out we have had it work now with up to 20' of grain on the top.
berkshire, I have never heard the half height of the diameter rule. On this unload system I haven't noticed much of a difference with how full or empty the bin, it seems to be more a function of time as to when they quit rotating. Once they quit rotating around, the grain level has to get down so the augers are exposed before they begin to rotate again. It does stand to reason that the more grain there is on top of the augers the more pressure that there is to prevent their rotation.
Thanks for all of your help!
RE: Use hydraulic motor for very slow rotation, or is there a better way?
Could you put radial pins on the spacing wheels and corresponding pockets in the bin floor, turning the augers into a crude crownwheel drive? Or conversely, circles of pins on the floor and pockets in the wheels?
If you think that would yaw the augers too fast, you could put planetary reducers (like modern bus wheel hubs) inside the wheels, at considerable cost in complexity.
Mike Halloran
Pembroke Pines, FL, USA
RE: Use hydraulic motor for very slow rotation, or is there a better way?
I believe you are correct in saying that driving the center gearbox will add stress to the augers, but I do not think it will be substantial enough to cause damage. Anyway, I am will to take that risk by trying it. Most of the time this system works the way it is, it seems it just needs a little help the rest of the time.
Thanks!
RE: Use hydraulic motor for very slow rotation, or is there a better way?
I used to work as a designer in the feed milling industry, that half height rule was based on the angle of repose of the grain, which for corn was usually somewhere around 35*. We had tried and discarded that rotating auger design in the 1960s, and came to the conclusion that for a flat bottomed bin, a full live bottom was the only way to go. We also used to recommend to customers that a conical bottom worked far better if they had the vertical space to install them . Your bin looks like a low cost bin of the type sold to farmers who stored for long periods and only drew from the bins one or twice a year.
B.E.
You are judged not by what you know, but by what you can do.
RE: Use hydraulic motor for very slow rotation, or is there a better way?
What is a full live bottom type unload?
RE: Use hydraulic motor for very slow rotation, or is there a better way?
see attachment.
B.E.
You are judged not by what you know, but by what you can do.
RE: Use hydraulic motor for very slow rotation, or is there a better way?
RE: Use hydraulic motor for very slow rotation, or is there a better way?
what about a pinion at the end of the conveyor shaft and a rack around the botton of the bin?
coupling between shaft and pinion could be done with some sort of friction coupling so the pinion wont spin fast
RE: Use hydraulic motor for very slow rotation, or is there a better way?
Spin the mechanism from center as you plan but instead of doing it at a constant very low speed, do it a little faster but in time intervals. You can use a torque limiter electric clutch if you dont want to start/stop the electric motor
Anyhow, I think an hydraulic motor is not the best option here
RE: Use hydraulic motor for very slow rotation, or is there a better way?
Thanks for the link, berkshire. I don't believe the full live bottom type of unload would be practical in my application.
ScottyUK, I have the Sumitomo representative's contact information for my area and will get in touch with him. They sound like the exact drive that I need.
lukin1977, see posts 11 and 12 about driving around the outside perimeter. You do have a good idea on starting and stopping the drive to get my low speed. I will see if one of the Sumitomo drives will get me slow enough. If not I may, look at starting and stopping to reduce the speed enough.
Thanks to you all!
RE: Use hydraulic motor for very slow rotation, or is there a better way?
http://www.helac.com/products-services/rotary-actu...
They are limited to 360 degree rotation or less. Perhaps run back and forth 0 to 180 to 0.
Ted
RE: Use hydraulic motor for very slow rotation, or is there a better way?
RE: Use hydraulic motor for very slow rotation, or is there a better way?
Since you appear to be stuck with what you have, would you consider changing the round ribbon screw conveyors for flat ribbon screw conveyors. you may get a little more grain breakage but I think it would take care of the fines problem because the flat faces would give more draw to the center. Again this is a ribbon conveyor not a full screw.
The other solution may be to throw a couple of Syntron feeders on the bin with the vibration direction towards the center and use them only when the screws stopped feeding. See page 12 of the attached catalog.
B.E.
You are judged not by what you know, but by what you can do.
RE: Use hydraulic motor for very slow rotation, or is there a better way?
I'm back on a desktop instead of my cell phone so it's a bit easier to post links: http://www.sumitomodriveeurope.com/en/coaxial-gear...
Listed for food applications, and reduction ratios available > 7500:1 with enough torque to shift the planet on its axis. I met these as a component of turbine barring gear and they were trouble-free in the ten or so years I was involved.
RE: Use hydraulic motor for very slow rotation, or is there a better way?
After considering all the suggestions, I plan to leave the existing screw conveyers in place. I will mount a 50:1 right angle gear reducer in the center of the bin. This reducer will have a drive shaft attached to it that will extend horizontally to the outside of the bin. On the outside of the bin I will drive the shaft with a Sumitomo 1003:1 ratio Cyclodrive gearmotor. The gearmotor will be powered with a variable frequency drive for additional speed control. Operating the motor at 10 hertz should give me about .006 RPM. I will be able to speed it up from there if I need to.