PTO RPM Indicator

[TractorRob]

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]

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]

Pretty good idea !!

 

[TractorRob]

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]

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]

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]

Very Ingenious!!

 

[aggiehortguy91]

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]

Thanks for all of the positive coments!

...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]

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

soundguy