PTO RPM Indicator

TractorRob · Jun 24, 2009

I have a grey market Mitsubishi MT3201D tractor that has a 4 speed PTO. I have not been able to find information on what speed the PTO settings were. I could tell when the PTO was somewhat close to 540 just from previous experience driving other tractors, but I wanted to be more accurate. I was trying to think of the easiest way to measure the PTO speed and wondered if I could trick a bicycle computer into displaying the PTO RPM. I knew from setting up bicycle computers before that you calibrate them by telling the computer how far the bicycle travels(in mm) for one revolution of the wheel. I did some calculations and determined that if you set this distance at 2682, then the MPH would be 1/10 the RPM of the wheel. Here is the Bike computer I used:

I installed it on my tractor yesterday and it works great! Now I can tell at a glance exactly how fast my PTO is turning(as an example, the 38.2 mph shown in the picture would be 382 RPM). I also get the added benefit of a clock. I haven't taken any pictures of the installation yet, but if anybody is interested I will post them after I do.

JMynes · Jun 25, 2009

That's pretty slick! I have a bike computer kicking around doing nothing, now I have a use for it!
Where did you put the little magnet? I think it would have to go on the PTO output shaft, since changing implements usually means changing PTO shafts, so the only common factor is the output shaft.

3RRL · Jun 25, 2009

Pretty good idea !!

TractorRob · Jun 25, 2009

I took some pictures this morning. I have an over running clutch on my PTO, so that gives me a perfect place to attach the magnet. The magnet is the lump wrapped in electrical tape. I plan to glue the magnet to the clutch, but I started out just using electrical tape to make sure it would work. Without the clutch on there, the PTO shaft would be the place to attach it.

bota7800 · Jun 25, 2009

Brilliant!

I just had to throw my cheap auto clock away. I could put a computer in the same place and it should be better suited to the weather.

I was on the Vetta site the other day, they had a wireless computer on closeout.

srjones · Jun 25, 2009

Great suggestion! Less than $10 at Amazon, but I might spend little more for better quality.

Amazon.com: Schwinn 17-Function Bike Computer: Sports & Outdoors

Bota7800, where did you see the closeout on vetta?

BlacknTan · Jun 25, 2009

Very Ingenious!!

aggiehortguy91 · Jun 25, 2009

Another of those "I can't believe I didn't think of it" ideas! Pure genious! If you got a bike computer that displayed cadence (revolutions/per min of the pedals), you wouldn't even need to calculate or could have a sensor for ground speed or the mid pto.

TractorRob · Jun 26, 2009

Thanks for all of the positive coments!

aggiehortguy91 said:
...If you got a bike computer that displayed cadence (revolutions/per min of the pedals), you wouldn't even need to calculate or could have a sensor for ground speed or the mid pto.

That is what I first thought about doing, but the ones I checked into that do cadence will not read high enough(most of them have an upper limit somewhere between 250 and 300).

Soundguy · Jun 26, 2009

does your tractor not have a tach on it with a pto mark?

soundguy

TractorRob · Jun 26, 2009

Soundguy said:
does your tractor not have a tach on it with a pto mark?

soundguy

It has a tach, but it does not have a pto mark on it.

AV8R62 · Jun 26, 2009

I used thay same spedometer on my zd21 lawnmower to show ground speed

Coyote machine · Jun 26, 2009

TractorRob,
Would you mind saying more about your over running clutch for your PTO- why you needed it - where you bought it, and anything else relevant to its use, please?
BTW, I like your idea- and I agree on the clock thing too- why have an instrument cluster without a clock? I don't like wearing my watch when using the tractor- its just something else to get destroyed when working the equipment-

and my Kioti also lacks a clock!?

Thanks!
CM

Soundguy · Jun 27, 2009

TractorRob said:
It has a tach, but it does not have a pto mark on it.

sounds like time for a china marker!

soundguy

bota7800 · Jun 27, 2009

srjones said:
Bota7800, where did you see the closeout on vetta?

Vetta Outlet Center but I am not sure now if it is a wireless unit - I have one ( on a bike) of a similar model number that is wireless.

I am also not sure if the wireless unit would work because the wheel unit is somewhat larger than the wired sensor.

TractorRob · Jun 27, 2009

Coyote machine said:
TractorRob,
Would you mind saying more about your over running clutch for your PTO- why you needed it - where you bought it, and anything else relevant to its use, please?...

On tractors like mine, if the PTO and tranmission are both in gear, then they will both turn together even when you push the clutch in. This can be aggravating, and even dangerous in a panic stop situation, when operating a PTO driven implement, such as when bush hogging. The momentum of the spinning bush hog will actually force the tractor to keep moving and can cause you to take several feet to stop the tractor, even with good brakes. The overrunning clutch is a ratcheting mechanism that allows the PTO driven implement to continue to spin so that you can stop the tractor quickly. The main reason for it is the safety issue of being able to stop quickly, but it also is handy when starting because you can bring the PTO up to speed before putting the tractor in gear so that you are not trying to get the tractor moving and the implement spinning at the same time. I got mine at Tractor Supply Company: Overrunning Clutch.

tatra805 · Jun 30, 2009

Tractorrob,

now that you mention it

i noticed that my iseki engages the pto a fraction earlier than the drive. It has 2 clutches (confirmed by manual, normal clutch assy for the drive and a maintenance free clutch system for the pto, although no further details mentioned) operated by the same pedal.

That way the pto is already up to speed before the tractor starts driving.

probably something normal but it kept me, newbie, wondering

but my pto is disengaged when pushing the clutch pedal.

I already looked for some levers that would command the PTO clutch but everything seems to be integrated. Shame as i would have put a switch on the 3point that engages a solenoid which commands the pto clutch to disengage when raising an implement.

Now i have to stop the tractor, disengage the pto, rise the implement and then drive to the next spot.

pmsmechanic · Oct 12, 2017

This has me thinking. I've often wanted a MPH/KPH indicator on my 4410 just because being able to ramp up the cruise control to the same speed would be handy for some of the jobs I do. The clock would be a nice bonus.

Edited to add: I just bought this. XCSOURCE Bike Wireless GPS Computer Bicycle Backlight LCD Digital Speedometer Cycling Waterproof Odometer 321 CS534: Amazon.ca: Sports & Outdoors

We'll see how that works when I receive it. CAD $16 for that price plus free shipping I figured it would be hard to go wrong.

TractorRob When you do your permanent mounting I would consider mounting the sensor on top of the pto. My thoughts are that it's less likely to collect junk on it that way.

Haha I just noticed how old this thread is.

Mace Canute · Nov 3, 2017

pmsmechanic said:
This has me thinking. I've often wanted a MPH/KPH indicator on my 4410 just because being able to ramp up the cruise control to the same speed would be handy for some of the jobs I do. The clock would be a nice bonus.

Edited to add: I just bought this. XCSOURCE Bike Wireless GPS Computer Bicycle Backlight LCD Digital Speedometer Cycling Waterproof Odometer 321 CS534: Amazon.ca: Sports & Outdoors

We'll see how that works when I receive it. CAD $16 for that price plus free shipping I figured it would be hard to go wrong.

TractorRob When you do your permanent mounting I would consider mounting the sensor on top of the pto. My thoughts are that it's less likely to collect junk on it that way.

Haha I just noticed how old this thread is.