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What is a PTO shaft?

Power Take Off (PTO) shafts are used to transmit power from a tractor or other source of power to an implement. Two speeds are commonly used with PTO shafts, 540 and 1000 rpm. RPM means revolutions per minute, the number of complete turns of the shaft in 60 seconds.



Did You Know?

The typical PTO shaft can:

  • Wrap up 424 feet of shoe lace in one minute at 540 rpm, or 785 feet of shoe lace at 1000 rpm. How long is your shoe lace?
  • Wrap your arm or leg around the PTO shaft nine times in one second at 540 PTO rpm, or nearly 16 times in one second at 1000 PTO rpm. Is your body that flexible?
  • Produce second degree burns on your skin, even if you are lucky enough to have the PTO strip only the cotton clothing from your body. Nylon and other synthetics will cut into skin and muscle tissue rather than rub across it.
  • Grind away skin, muscles, tendons, and break bones starting in less than three-fourths of one second when you are caught by an unshielded PTO shaft.
  • A very strong man can generate about three-fourths of one horsepower. A tractor transmits nearly all of the engine horsepower to the PTO shaft. There is simply no contest; even between a very strong man and a PTO shaft -- the tractor will win.



PTO Entanglements

North Dakota usually has from four to six PTO entanglements per year that result in severe injury or death. There are many more entanglements, however, that result in someone's clothing being partially or completely torn off. This can result in severe skin burns when the clothing tightens up as it is pulled from the body.
Most farmers don't have to try too hard to remember someone who has been caught by an unshielded PTO shaft. Some older people will chuckle about a long-past entanglement. But that chuckle is more of a nervous reaction than true humor. PTO entanglement is not funny!
Any machine that is powered by an unshielded PTO shaft is dangerous. The brand of machinery has nothing to do with its safety, if the PTO is not shielded. You can work with any color of machinery you wish; red, green, blue, yellow, orange -- take your choice -- if the PTO shield is missing, it is dangerous!




How Can You Be Safe When Using PTO Shafts?


  • First, make sure the shaft is shielded. This includes the driveline shield that covers the implement driveline, and the master shield which covers the universal joint and PTO stub shaft on the tractor.
  • Maintain the shield so it can work for you. PTO driveline shields are usually mounted on bearings, so they need to be maintained. Always REPLACE the shield when it is damaged or missing.
  • Next, keep a safe distance from it when in use. Keep others away, too. How far? A distance of twice your height is a good start.
  • Allow only those who absolutely must be in the area to be there. Keep all children away!
  • Always pay attention to what is happening. Most PTO victims were caught by surprise.
  • If something goes wrong -- stop the machinery; take the PTO out of gear, stop the engine and set the brake. Put the keys in your pocket before working on the machinery.
  • When stopping the machinery for any reason -- end of work, lunch, repairs, or communication -- take the PTO out of gear, stop the engine and set the brake.




More Thoughts About PTO Shafts and Shields


  • The average replacement PTO shield should cost less than $50 according to North Dakota implement dealers, and will take less than two hours to install.
  • Can you get an ambulance ride to the hospital for less than $50?
  • How much health/hospitalization insurance can you buy for $50?
  • Can you buy an artificial arm or leg for $50 or less?
  • Can you buy a funeral for less than $50?
  • Can you look at a picture of your wife or family and say that PTO shields are not worth the cost or effort?
A replacement PTO shield is simply the cheapest insurance you can buy. The time spent to install and maintain a PTO shield is clearly the most valuable and productive time you can spend in your life!


Take a look at this Video:




And this one:

 

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Discussion Starter · #3 ·
What Causes PTO Shaft Vibration?

From this link: http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/eng5241

[HR][/HR]
PTO vibration is caused by the universal joints and is especially pronounced when cornering. The output velocity of a single U-joint operating at an angle fluctuates, even though the input velocity is constant. This output velocity fluctuation becomes greater as the angle of the U-joint is increased. To eliminate the velocity fluctuation and hence the PTO vibration, two universal joints are used. The velocity fluctuation caused by the first U-joint is cancelled by the second U-joint, only if both are operated at the same angle.
Since most tractor/implement PTO's use the two U-joint system, why may there still be PTO vibration? It is because the U-joints are not operating at the same angle.
FIGURE 1 shows a typical PTO hook-up. For the U-joints to operate at the same angle, the distance from the end of the tractor PTO shaft to the hitch point (Dimension A) should equal the distance from the hitch point to the end of the implement input shaft (Dimension B).
Figure 1.
Most tractors with a 540 rpm PTO have a distance of 14 inches from the end of the tractor PTO shaft to the hitch point.
Most implements, however, have a distance greater than 14 inches from the hitch point to the end of the implement input shaft. This design is necessary to allow sufficient telescoping action of the PTO shaft, so the shaft does not bottom out on sharp turns and does not allow the two parts of the PTO shaft to separate when the PTO is in line with the drawbar. This geometry however, does not allow the U-joints to operate at equal angles, when cornering.
Many implement manufacturers are supplying a tractor hitch extension with their implements. This extension increases the distance from the end of the tractor PTO shaft to the hitch point. The implement and PTO shaft are designed around this new geometry so the U-joints will operate at equal angles. This geometry is commonly called the EQUAL ANGLE HITCH. Existing equipment can be modified to obtain an equal angle hitch.
A tractor hitch extension can be fabricated to increase the distance from the end of the tractor PTO shaft to the hitch point. The implement hitch will have to be shortened an equal amount. This allows the overall length of the PTO shaft to remain the same.
For example, a 540 rpm PTO driven machine is hitched to a tractor as shown in FIGURE 2A. The distance from the end of the tractor PTO shaft to the hitch point is the standard 14 inches. The distance from the hitch point to the input shaft of the machine is measured and found to be 20 inches, making the overall distance 34 inches (14 and 20). For the PTO to operate at equal angles the hitch point should be 17 inches (34 divided by 2) from both the end of the tractor PTO and the input shaft of the machine.
As shown in FIGURE 2B, a 3 inch extension is bolted to the tractor drawbar and the machine hitch is shortened 3 inches. It should be noted the overall distance of 34 inches has not changed and the original PTO shaft can still be used.
Figure 2A.

Figure 2B.
However, the machine cannot be operated unless the drawbar extension is bolted to the tractor drawbar.
Most tractors with 1000 rpm (1-3/8" diameter) PTO shaft have a distance of 16 inches from the end of the tractor PTO shaft to the hitch point. The same procedure can be used as in the example, however, the dimensions will be different.
These modifications should not be undertaken unless the person doing the modifications is completely familiar with the above procedure.
It is also important to phase the U-joints correctly. The correct and incorrect phasing of U-joints is shown in FIGURE 3. Proper phasing of the U-joints allows the velocity fluctuation caused by the first U-joint to be cancelled by the second. Improper phasing compounds the velocity fluctuations and will cause severe vibration.
The two parts of many PTO shafts are designed to fit together only the correct way. This eliminates phasing problems.

Figure 3.

The design of a tractor/implement PTO with three U-joints is more complicated than a two joint system. The third U-joint in the drive line is usually located at a gear box or sheave on the machine. If this U-joint operates at an angle of only a few degrees, it is only necessary to ensure that the U-joints at the hitch are properly phased and operate at equal angles.
However, if the third U-joint operates at an angle it may be impossible to eliminate PTO vibration even if the U-joint at the hitch is phased and operating at equal angles.
 

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Discussion Starter · #4 ·
Great Read here also

Download these .pdf's for some good thrown reading:
 

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More to Come Soon

This space is intentionally left blank (except for this message of course:lol:)
 

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great thread, i think that every time someone buys a tractor, the salesman should educate them on PTO safety as well as show them that video, it can happen so quickly
 
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It would be interesting to see the same videos made with crash test dummies instead of straw men. Old equipment could be used as Buster would no doubt cause some damage to the equipment.
 
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As I am new to the PTO shaft. I have 4 questions.

#1 what is the minimum engagement that the 2 pto shaft sections should have with each other. is there a standard?

#2 does the pto shield rotate with the shaft or is it to be chained in place as to not spin?

#3 is the use of a pto shaft extender a viable option? or does it lead to more problems?

#4 is there considered a "normal" amount of vibration to be expected? or is it to run completely true?

Thanks
 

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Please red comments below.

As I am new to the PTO shaft. I have 4 questions.

#1 what is the minimum engagement that the 2 pto shaft sections should have with each other. is there a standard?

If I recall correctly, Comer (my Bush Hog's shaft manufacturer) recommends a minimum of 6" of engagement.

#2 does the pto shield rotate with the shaft or is it to be chained in place as to not spin?

Chained in place is preferred as the idea is not to have any exposed rotating parts.

#3 is the use of a pto shaft extender a viable option? or does it lead to more problems?

I have a 4" extender on mine to compensate for the quick-hitch.

#4 is there considered a "normal" amount of vibration to be expected? or is it to run completely true?

Some vibration is normal; but if it's shaking the tractor and/or implement, something is wrong.

Thanks
 
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I am not so sure I agree with the video guy.

If you cut the shaft so it is within an eighth of an inch with the implement end in place and the tractor end almost butting the end of the output shaft, in the process of hooking up to the tractor you will slide the shaft onto the tractor splines a couple of inches. I fail to see why if you don't do his two inch thing it will cause binding. That is so long as you have that eighth of an inch when the shaft is close to in a straight line as opposed to a large deviation from straight. I think I gave myself about half an inch but only intend on using that implement on one tractor. I am not sure that the two inches is enough for going between all possible tractors. The manual for my tractors says to check for binding (and separation) essentially any time you hook up a pto shaft. Probably says move it up and down and see if anything rubs.

Probably ought to take the plastic stuff completely off, file the cut edges and clean up the saw chips and filing residue. Make sure the slots the plastic bushings for the guards are clean and lubricated and re assemble.

Did He start the tractor from someplace besides the operators seat?

I will have to see if my square shaft ones are in phase properly or if the square is a bit of a rectangle so it can't be done wrong. Earlier picture not the video.

fran
 

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One summer when I was 16-17 I was helping a guy bail hay, running the elevator. Like an idiot I came up behind the tractor to reach the PTO control. To this day I'm not sure how it happened but somehow my leg managed to lift off the ground and hover over the shaft. I felt the leg of my jeans get knocked a couple times as the shaft was spinning. Somehow my body reacted before I even realized what was occurring. Luckily there was a hay wagon right beside me - I grabbed a hold of the wagon and pulled right as my pant leg caught on the shaft. In zero time I ripped exactly half of my pants off my leg, around my boot. I got incredibly lucky to have the jeans rip the way they did. I'm not sure why/how my body knew to grab for the wagon when it did, I hadn't even processed what was tugging at my leg by the time I was 4-5' off the ground on the side of the wagon with half my ass exposed.

One cannot stress the importance of proper guards enough. I grew up running equipment and knew better than to approach a tractor from behind while running equipment but the mind doesn't necessarily think after working a 16hr day in 100 degree temperatures. I still think the guards are a PITA, but you can bet your retirement funds that I'll be using them.

I think I owe my guardian angel a beer when we meet..
 

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Discussion Starter · #13 ·
Great story J, and an even better reminder for all of us to hear a "real life" experience. Glad your still here to tell it :yahoo: :good2:
 
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Yup, tractoring is serious business. My aunt wasn't quite that lucky. She got wrapped up in a pto shaft back in the 70's. It broke her back and she was paralyzed the rest of her life. You always need to be alert no matter the time of day or the where you are in the task at hand. Stay safe everyone.
 

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I try and wear sweat pants and the like when I am running PTO implements. Something that really rips easily.
 
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Interesting facts from this link: Publications





Power Take Off (PTO) shafts are used to transmit power from a tractor or other source of power to an implement. Two speeds are commonly used with PTO shafts, 540 and 1000 rpm. RPM means revolutions per minute, the number of complete turns of the shaft in 60 seconds.




Did You Know?

The typical PTO shaft can:

  • Wrap up 424 feet of shoe lace in one minute at 540 rpm, or 785 feet of shoe lace at 1000 rpm. How long is your shoe lace?
  • Wrap your arm or leg around the PTO shaft nine times in one second at 540 PTO rpm, or nearly 16 times in one second at 1000 PTO rpm. Is your body that flexible?
  • Produce second degree burns on your skin, even if you are lucky enough to have the PTO strip only the cotton clothing from your body. Nylon and other synthetics will cut into skin and muscle tissue rather than rub across it.
  • Grind away skin, muscles, tendons, and break bones starting in less than three-fourths of one second when you are caught by an unshielded PTO shaft.
  • A very strong man can generate about three-fourths of one horsepower. A tractor transmits nearly all of the engine horsepower to the PTO shaft. There is simply no contest; even between a very strong man and a PTO shaft -- the tractor will win.



PTO Entanglements

North Dakota usually has from four to six PTO entanglements per year that result in severe injury or death. There are many more entanglements, however, that result in someone's clothing being partially or completely torn off. This can result in severe skin burns when the clothing tightens up as it is pulled from the body.
Most farmers don't have to try too hard to remember someone who has been caught by an unshielded PTO shaft. Some older people will chuckle about a long-past entanglement. But that chuckle is more of a nervous reaction than true humor. PTO entanglement is not funny!
Any machine that is powered by an unshielded PTO shaft is dangerous. The brand of machinery has nothing to do with its safety, if the PTO is not shielded. You can work with any color of machinery you wish; red, green, blue, yellow, orange -- take your choice -- if the PTO shield is missing, it is dangerous!




How Can You Be Safe When Using PTO Shafts?


  • First, make sure the shaft is shielded. This includes the driveline shield that covers the implement driveline, and the master shield which covers the universal joint and PTO stub shaft on the tractor.
  • Maintain the shield so it can work for you. PTO driveline shields are usually mounted on bearings, so they need to be maintained. Always REPLACE the shield when it is damaged or missing.
  • Next, keep a safe distance from it when in use. Keep others away, too. How far? A distance of twice your height is a good start.
  • Allow only those who absolutely must be in the area to be there. Keep all children away!
  • Always pay attention to what is happening. Most PTO victims were caught by surprise.
  • If something goes wrong -- stop the machinery; take the PTO out of gear, stop the engine and set the brake. Put the keys in your pocket before working on the machinery.
  • When stopping the machinery for any reason -- end of work, lunch, repairs, or communication -- take the PTO out of gear, stop the engine and set the brake.




More Thoughts About PTO Shafts and Shields


  • The average replacement PTO shield should cost less than $50 according to North Dakota implement dealers, and will take less than two hours to install.
  • Can you get an ambulance ride to the hospital for less than $50?
  • How much health/hospitalization insurance can you buy for $50?
  • Can you buy an artificial arm or leg for $50 or less?
  • Can you buy a funeral for less than $50?
  • Can you look at a picture of your wife or family and say that PTO shields are not worth the cost or effort?
A replacement PTO shield is simply the cheapest insurance you can buy. The time spent to install and maintain a PTO shield is clearly the most valuable and productive time you can spend in your life!


Take a look at this Video:




And this one:



Absolutely great information, and not only information, but life and limb saving information. My Brother in Law, a few years ago had a large pto driven rock rake. He always wore and still does, old overalls. He had a pair on that should have been trashed a long time ago. He had gotten off the tractor because something had gotten stuck, the PTO caught hold of a piece of his pant leg, and thank goodness after a heck of a fight, left him standing in just his boxer shorts. Bruised his legs, and some places on his waist and butt. If he had new ones on, it would have probably severely injured or killed him. It torn them off him like an old rag!!!
 

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I just hope people realize that just b/c you know better doesn't mean you won't make a stupid mistake after a long exhausting day fighting dehydration. After a good nights rest everyone knows better but after working all day its hard say how on point you'll be.
 

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Sure, no worries.
 
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