Measuring/calculating PTO speed (not PTO speed = Machine speed / implement speed)

[ruffdog]

Like this?..


View attachment 783595

This is an old one made by Warner Instrument Co in Beloit WI

 

[OldNick]

It's very common for these smaller Japanese tractors to have 4 PTO speeds. Something like 540 - 750 - 860 - 1000. All achieved at the rated RPM, probably in the 2500 engine RPM range like Ruffdog says.

It's also common to use the 750 RPM with less engine RPM to achieve 540 PTO RPM with less engine RPM, also known as 540E (E for economy).

Ahah! OK, thanks for that. Sounds like all this theory is overthink. If I had not found out about it, I would have just experimented until it sounded and felt right. Back in my younger days that's what I used to do.

 

[OldNick]

It should be noted that running a higher pto gear at a lower engine speed will greatly reduce available HP.

And even more so, reduce torque for the implement. But that's where you drop the _tractor_ gear and just move slower.

 

[Tinhack]

I went ahead and added a 12v digital tach even though the new dash has a tach. I wanted to verify the accuracy since my tach is driven by a cable. Come to find out. it's spot on. The push-on/push-off switch and the box are waterproof as is the sender. The sleeve on the output shaft has a magnet and set screw.

 

[zzvyb6]

A 6 spline shaft at 540 rpm would generate 3240 square wave beats per second if it made contact with a flexible strip. Remember clamping playing cards to your bike wheels ?
Then ask Google to play you a 3240 Hz. tone on your phone and compare the 2 tones. Adjust the throttle accordingly in any of the transmission selectors. The tone is actually played on a youtube clip loaded with your specified frequency. Try it ! Even though the generated tone is a sine wave, you can't miss the hook up (well yas you can if you're DEAF, but that would kill the mood). As you get close to a match, you might hear a beat frequency as the difference between the two signals. Ignore any sharks that might appear in the area....

 

[OldNick]

A 6 spline shaft at 540 rpm would generate 3240 square wave beats per second if it made contact with a flexible strip. Remember clamping playing cards to your bike wheels ?
Then ask Google to play you a 3240 Hz. tone on your phone and compare the 2 tones. Adjust the throttle accordingly in any of the transmission selectors. The tone is actually played on a youtube clip loaded with your specified frequency. Try it ! Even though the generated tone is a sine wave, you can't miss the hook up (well yas you can if you're DEAF, but that would kill the mood). As you get close to a match, you might hear a beat frequency as the difference between the two signals. Ignore any sharks that might appear in the area....

Thanks for that idea. It is good. There are actually a couple of sites ... Online Tone Generator - Free, Simple and Easy to Use....for instance. Does all the standard wave forms.

However I have other jobs for a tacho, where doing that trick would be a lot harder..a saw blade for instance

I think I will go for the laser. Fleabay has them for Aud $20, post free.

There is no real urgency. The weather here in Perth is VERY hot and dry ATM. This is about a flail mower and I am not about the rip around with steel being passed through the grass and small stones!

 

[zzvyb6]

I had a PTO alternator to power the house & barn for which getting 60 Hz from the A/C output was needed. I used a Kill-A Watt device that plugs into the genny outlet to measure the frequency of the output voltage. This verified my 540 pto Tach indicator. The Kill-A-Watts are available here in most hardware stores and fleabay/Amazon etc. $20.

 

[CobyRupert]

Thinking outside the box, would this works using a standard 60hz incandescent light?

Find where 600 PTO rpm is (because it works well with 60 sec/min and 60 cycles/sec.) as follows:

The PTO shaft turning 600 rpm, means 10rev/sec. The PTO shaft has 6 splines. At 10 revs per sec, that means 60 splines pass by per second.

An incandescent light operating at 120v/ 60 hertz flashes 60 times per second. That means, the splines will look like there not moving when PTO is at exactly 600rpm. (“Strobe effect”.)

Once you know engine rpm for 600 PTO rpm, multiple that by .9 for 540 PTO rpm engine setting.

The problem, you might also observe “stand still” strobe effects at 15, 30, 60, 120, splines/sec, (150, 300, 600, 1200 rpms, maybe others?), so you have to know you’re operating in the right ballpark when looking for the 600 rpm strobe effect.

Suuuuuure, that’ll work…..in theory!

 

[ning]

Thinking outside the box, would this works using a standard 60hz incandescent light?

Find where 600 PTO rpm is (because it works well with 60 sec/min and 60 cycles/sec.) as follows:

The PTO shaft turning 600 rpm, means 10rev/sec. The PTO shaft has 6 splines. At 10 revs per sec, that means 60 splines pass by per second.

An incandescent light operating at 120v/ 60 hertz flashes 60 times per second. That means, the splines will look like there not moving when PTO is at exactly 600rpm. (“Strobe effect”.)

Once you know engine rpm for 600 PTO rpm, multiple that by .9 for 540 PTO rpm engine setting.

The problem, you might also observe “stand still” strobe effects at 15, 30, 60, 120, splines/sec, (150, 300, 600, 1200 rpms, maybe others?), so you have to know you’re operating in the right ballpark when looking for the 600 rpm strobe effect.

Suuuuuure, that’ll work…..in theory!

Incandescent lighting doesn't really flash, because the filament itself is incandescent, and it doesn't markedly change temperature/light output during the brief interruption of power.

Fluorescent lighting does flicker with the cycling, and many people can see the flickering at 60Hz. You'd be better off using a fluorescent.

 

[dieselscout80]

Well I certainly do not want to run my engine at 2500! Anyway does that have anything to do with a 4-speed PTO, or refer to my question?

Why not????

Tractors are designed to run at rated power & rpm all day long everyday for many thousands of hours.

PTO operated equipment is designed to be run at a set speed typically 540 or 1000 rpm for most North American tractors. Run at lower speeds may not operate effectively, but some do okay at lower speeds.

 

[CobyRupert]

Incandescent lighting doesn't really flash, because the filament itself is incandescent, and it doesn't markedly change temperature/light output during the brief interruption of power.

Fluorescent lighting does flicker with the cycling, and many people can see the flickering at 60Hz. You'd be better off using a fluorescent.

Plus I’m wrong about 60 flickers per second, it would be 120 flickers per second..but I think* interference patterns would be similar.

 

[BigBlue1]

Why not????

Tractors are designed to run at rated power & rpm all day long everyday for many thousands of hours.

PTO operated equipment is designed to be run at a set speed typically 540 or 1000 rpm for most North American tractors. Run at lower speeds may not operate effectively, but some do okay at lower speeds.

Yep. That's what the tractor is designed for. And that RPM is probably where the tractor is making peak HP/power. It's the RPM that *should* be used for running a PTO-driven implement. Certainly there are situations where load is light and rotating speed isn't important and you can run at different RPM, but those are the exceptions, not the rule.

 

[OldNick]

Why not????

Tractors are designed to run at rated power & rpm all day long everyday for many thousands of hours.

PTO operated equipment is designed to be run at a set speed typically 540 or 1000 rpm for most North American tractors. Run at lower speeds may not operate effectively, but some do okay at lower speeds.

Well apart from anything else, I don't particularly want to sit on a diesel at 2500 RPM, and there are the neighbours to consider. The difference between 1500 and 2500 RPM in regard to noise and vibration is pretty steep.
I will just have to try gearing and engine speeds to find the sweet spot. I can use the PTO gearing and the tractor gearing to find what works. In my case economy is not the major concern, so I can use less power and higher PTO gearing, and just drive slower.

BTW is the forum looking strange to others as well as me? I am suddenly seeing the HTML (I assume) instead of the normal WYSIWYG result.

 

[OldNick]

Plus I’m wrong about 60 flickers per second, it would be 120 flickers per second..but I think* interference patterns would be similar.

Or an LED? A lot more compact. I suppose there is the problem with mains voltage, but there are lots of LED mains bulbs out there.

 

[ruffdog]

Well apart from anything else, I don't particularly want to sit on a diesel at 2500 RPM, and there are the neighbours to consider. The difference between 1500 and 2500 RPM in regard to noise and vibration is pretty steep.
I will just have to try gearing and engine speeds to find the sweet spot.

Most tractors will run pretty smooth at pto speeds and rougher at slow rpms. Maybe there is a mechanical issue with your tractor that if repaired, would make it more enjoyable.

 

[OldNick]

Most tractors will run pretty smooth at pto speeds and rougher at slow rpms. Maybe there is a mechanical issue with your tractor that if repaired, would make it more enjoyable.

No it's in good condition (it was overhauled before I bought it) and starts and runs well. I guess it's mainly the noise of the exhaust. At anything up to 1500 RPM it's pretty mild, but as it ramps up it gets a lot louder. I wear earplugs, but I am still conscious of the neighbours.

I used to have an A/C HD16 DG dozer, so I should not be such a wuss I guess. But that was back when the sheer thunder of that thing was still a kick, and I was 1Km from the nearest neighbour.

 

[LD1]

A adjustable strobe light would work too. Every place I have ever worked had one....and they are very handy in an industrial setting

Can make a moving peice of equipment look stationary. Nice for diagnosis problems of equipment timing for production equipment.

We also used it to read part numbers on things like belts and shelves, or chains and sprockets without having to stop a production line.

They were alot of fun to play with

 

[boatmoter]

I DAGS and searched the forum for PTO speed etc.

So. I have a Hinomoto N279 32HP tractor. Maybe I bought badly as it does not even have its own section here

However.. The N279 has a 4 gear/speed PTO. I know the flail mower I have bought requires a 540 RPM PTO speed. But I do not know for the N279 what PTO speed results from what engine speed in each PTO gear. The Tacho has no indication of PTO speed for each PTO gear.

So how do I measure the PTO speed? I tried writing on a spline with liquid paper. But 540 RPM is what.... 9 per second. Try counting that.

To add to that, the 4 PTO gears do not make sense to me: they do not go 1=slowest 2=a bit faster...etc. They seem to duck and dive, based purely on non-measure obs.

Or do I just wing it, going as high-gear as I can without labouring, running at 1500 RPM of the 200RPM of the N279, and yet getting a decent thrashing?

I understand that the whole thing revolves around also looking at Forward Movement Speed and is all a balancing trick. But I would like to know the figures as a starting point.

I have a compact international 234 diesel, I was debating to get a pto generator or a gas. when I seen the pto generators needed to run at 840, I checked for the pto speed on my tractor,it would need to run at 2200 RPM's to get 840 at the pto. I bought a gas generator. I didn't want the engine to run that long at 2200 rpm. but I would run yours at that RPM since it is not for half the night and all day at a time. I would see no problem with 2200.

 

[MHarryE]

I went ahead and added a 12v digital tach even though the new dash has a tach. I wanted to verify the accuracy since my tach is driven by a cable. Come to find out. it's spot on. The push-on/push-off switch and the box are waterproof as is the sender. The sleeve on the output shaft has a magnet and set screw.

View attachment 783664

View attachment 783665

Excellent idea. My Kubota M7-171 has the equivalent. Most tractors that have multiple PTO speeds assume PTO speed depending on gear ratio selected (in my case the tractor has 540 and 1000 rpm and in addition 540E and 1000E). Instead of marking engine speed at which you should get a certain PTO speed, mine has a sensor similar to your add-on but built into the housing with sensor lugs on the base of the output shaft. On my multi-function display, I can read the exact PTO speed. In fact most farm size tractors have a PTO speed sensor so they read speed rather than have the operator assume the speed. Maybe someday they will work their way to CUT's.

 

[CoyPatton]

Well I certainly do not want to run my engine at 2500! Anyway does that have anything to do with a 4-speed PTO, or refer to my question?

Your tractor diesel engine was designed to be ran at its operating RPM all day. You will actually run a greater risk of damage at a reduced RPM and and heavy load.
I assume it has a geared transmission, load is determined my many factors, most you have little to control over. Your 2 biggest control factors under your control are throttle and ground speed. Get your RPM’s up and select a gear that provides the ground speed to not overload the tractor.
I own a Yanmar tractor, it has a 3 speed PTO. I run 2400 engine RPM and PTO gear 1 it is not exactly 540, but close. I do not remember the numbers we got when I checked it with a friends tack gun. However it was close. Dropping engine RPM’s has a direct relationship to lowering PTO RPM’s. At 2000 engine RPM’s, I had under 500 PTO RPM’s.
I once saw a post address RPM’s in other PTO gears on the Yanmar section, but I only have a few PTO implements snd they are 540. One was to get near 1000 PTO RPM’s. Frankly that scares me on my little tractor with limited safety features and does offer anything I need or want.