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dfwallis 
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 Topic: CA PTO Speed vs Engine RPM
Posted: 17 Jun 2024 at 2:39pm |
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I guess on a CA, 540 (538) RPM occurs at 1650 engine (max governed) RPM. I guess that may squeeze every last drop of capability out of it but assumes that you never want a higher PTO speed. Is there a good reason for doing it this way?
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DrAllis
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Posted: 17 Jun 2024 at 2:47pm |
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I'll assume that 1650 RPM engine speed on a "CA" is 540 RPM on the PTO. You want to operate at that speed for combines, balers, sickle mower, etc. Now, for a silage blower or forage chopper you're better off at FULL throttle 1860 RPM. You'll get much more done and those machines can take the extra speed.
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dfwallis
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Posted: 17 Jun 2024 at 6:26pm |
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I thought1650 is maximum governed RPM. I know at max RPM it doesn't really sound likes it's under any stress at all.
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PaulB
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Posted: 17 Jun 2024 at 6:50pm |
 dfwallis wrote:
I thought1650 is maximum governed RPM. |
Apparently you've never read an Operators manual for a CA tractor.
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If it was fun to pull in LOW gear, I could have a John Deere.
If you can't make it GO... make it SHINY
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dfwallis
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Posted: 17 Jun 2024 at 8:11pm |
PaulB wrote:
dfwallis wrote:
I thought1650 is maximum governed RPM. |
Apparently you've never read an Operators manual for a CA tractor.
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Well, I have, but I don't recall that particular tidbit. And at the moment, it's 1000 miles away locked in storage.
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DrAllis
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Posted: 17 Jun 2024 at 9:32pm |
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Imagine the tractor connected to a PTO dynomometer. With the engine running wide open at no load, the PTO speed will be approx 610 RPM while the engine is at 1860 RPM. When you apply a load with the dyno and pull the engine down to 1650 RPM, the governor opens the carburetor throttle plate to be straight up/clear open/max air/fuel flow. This is "rated" engine speed at full load. That 1650 speed is the maximum HP the tractor was designed to produce.
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dfwallis
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Posted: 18 Jun 2024 at 12:21pm |
So, I guess I will need to add a tach. I find nothing really suitable, so I'm going for a cheapy inductive one for now. I have all the parts I need to create a custom Arduino unit. I may think about that over the winter. Digital display of engine, pto, road speed for each gear. Well, I'd need a larger display than I have or I could cycle through 2 lines at a time. Probably leave the engine/pto showing most of the time and periodically cycle through gear speeds. A nice large color display would be nice :) I could add some graphics to it.
hmmm...engine diagnostics??
Edited by dfwallis - 18 Jun 2024 at 12:52pm
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steve(ill)
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Posted: 18 Jun 2024 at 12:50pm |
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Normally the pto speed is not that critical that you have to "adjust" it... I run the sickle MUCH SLOWER than 540 rpm.. do it " by ear"....a bush hog mower you can run a little over 540 rpm... dont make any difference.. Dont have to be EXACT.
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Like them all, but love the "B"s.
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dfwallis
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Posted: 18 Jun 2024 at 12:54pm |
steve(ill) wrote:
Normally the pto speed is not that critical that you have to "adjust" it... I run the sickle MUCH SLOWER than 540 rpm.. do it " by ear"....a bush hog mower you can run a little over 540 rpm... dont make any difference.. Dont have to be EXACT. |
Sure, but I can't tell if it's at 300 or 500 by ear. For finish mowing, you want to get the blade tip speed in the ballpark.
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steve(ill)
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Posted: 18 Jun 2024 at 1:02pm |
I would guess you can tell closer than you think.... Rated speed of 1650 or HIGH throttle of 1800... You know the PTO is runnint 540 - 600 rpm during that time... If you cut the speed 20% from 1650 your engine would be running 1300 rpm.. and the PTO would drop to about 450 rpm..... that should be easily noticeable..
Now if you want a Digital Display to monitor everything that is happening, thats a different story...   ............ just saying its not a necessity... Mower runs AS FAST as you can get it to go....... and i run the sickle about 350 rpm..  ... of course the belt drive has a step down pulley so the sickle shaft might STILL be 540 rpm.....too much more speed and the 75 year old mower looks like it might fly apart !!
Edited by steve(ill) - 18 Jun 2024 at 1:05pm
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Like them all, but love the "B"s.
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dfwallis
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Posted: 18 Jun 2024 at 1:18pm |
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An inductive digital tach is like $13. Kind of a no brainer. Arduino isn't much more than that (but I already have it so $0). The software would be pretty minimal. Not much more complicated than blinking an LED. So, why not. I get bored in the winter time :)
Edited by dfwallis - 18 Jun 2024 at 1:18pm
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bigal121892
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Posted: 18 Jun 2024 at 5:04pm |
Have you seen the new Arduino GIGA display, touchscreen.
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dfwallis
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Posted: 18 Jun 2024 at 5:30pm |
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Yes, a bit pricey though and not really going to need a touch screen maybe. I do have ideas for one though. I also thought about making it multi-tractor compatible. Just ground the right pin to select B/C/CA/?
Edited by dfwallis - 18 Jun 2024 at 5:31pm
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dfwallis
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Posted: 20 Jun 2024 at 7:37pm |
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I experimented with an inductive pickup circuit. Works but still a bit noisy. I think I'll first try an IR sensor solution. Hall sensor would require a magnet be attached and causes some mass imbalance (and might detach at high rpm). An IR sensor can use a strip of white paint or plastic. Good contrast is easy if you paint the (flywheel, pulley) surface black before painting the white strip. Of course you either need a longer sample time (slow update) or you need multiple strips equally spaced to get a more accurate reading.
Edited by dfwallis - 20 Jun 2024 at 9:03pm
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PaulB
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Posted: 21 Jun 2024 at 6:43am |
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Definitely over thinking this issue. Use the KISS method. I've use a boat tachometer on many of my pulling tractors. They are weatherproof and have lower range scales than automotive tachometers.
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If it was fun to pull in LOW gear, I could have a John Deere.
If you can't make it GO... make it SHINY
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dfwallis
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Posted: 21 Jun 2024 at 9:19am |
PaulB wrote:
Definitely over thinking this issue. Use the KISS method. I've use a boat tachometer on many of my pulling tractors. They are weatherproof and have lower range scales than automotive tachometers. |
You're always trying to talk me out of having fun. Where's your sense of adventure? I've already bought and tested the $13 (waterproof) cheapo. I MAY decide that's enough. I did look at dozens of different tachs and didn't find anything that matched the desired functionality (or that operated at 6V). My goal is to display the RPMs and gear speeds with the correct calculated gear ratios, in real time. That's really easy.
I guess I won't tell you about my device that generates unidirectional linear motion via multiple stepper motor controlled actuators with a tailored and synchronized motion profile. Now that was overthinking...but it works...unidirectional linear motion without throwing a mass out the back (and without depending on friction).
Edited by dfwallis - 21 Jun 2024 at 1:48pm
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