Dumb question regarding PTO shafts and category... - Allis-Chalmers

Author Fantrum
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Joined: 02 Feb
Location: Missouri
Points: 240 Post Options    Thanks(0)    Quote  Reply Topic: Dumb question regarding PTO shafts and category...
    Posted: 28 Apr at 1:48am Okay, I admit it. This is a stupid question.. But I cannot find a good answer on the internet. Please forgive me.

I have my 190XT with category II 3-point hitch. I realize (unless I'm wrong) that on many implements I can swap out the lift pins to make them category II as well. However, what about the PTO shaft? Are there differences? For example, a tiller that is cat I. Could I swap lift pins to make it cat II and have the PTO shaft function properly still?I'm pretty ignorant on swapping categories, so forgive me. Sponsored Links DiyDave
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Joined: 11 Sep
Location: Gambrills, MD
Points: Post Options    Thanks(0)    Quote  Reply Posted: 28 Apr at 4:36am I don't think there is any difference in PTO, as long as its 540... and the correct length. Now hooking an 80 HP tractor to a 40 HP gearbox may have some consequences, though.  Make sure that the drive line has a clutch or shear bolt, to protect the tiller... Source: Babylon Bee. Sponsored by BRAWNDO, its got what you need! jaybmiller
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Joined: 12 Sep
Location: Greensville,Ont
Points: Post Options    Thanks(0)    Quote  Reply Posted: 28 Apr at 5:40am You don't modify the tiller pins ! You buy a couple 'Cat1 -Cat2 ' bushings, that slide onto the tiller's Cat1 pins then hookup to the 3PH, CAT2 liftarms.The PTO will be 'universal'..as long as it's 540 and 1 3/8", 6 spline unit.Early tractors (Ford 9N,2N..maybe the 'B' ?) had smaller diameter PTO shafts ( 1 1/8" ?). They didn't have a lot of HP, so didn't need the bigger diameter shaft. Since then the industry standardized on ONE size-fit-all. Course there's another 'standard' for the (?) RPM PTOs.....Odds are real good, you've got enough HP to turn a 6' tiller. My D-14 can spin a 5' unit all day long.
3 D-14s,A-C forklift, B-112
Kubota BX23S lil' TOOT( The Other Orange Tractor)

Never burn your bridges, unless you can walk on water PaulB
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Joined: 12 Sep
Location: Rocky Ridge Md
Points: Post Options    Thanks(0)    Quote  Reply Posted: 28 Apr at 5:55am The problem of just swapping Cat-II pins or adding the bushings to a Cat-I implement and hooking it to a Cat-II tractor is; The Cat-I is 26" wide at the pins and Cat-II is 32" wide at the pins. You need the Cat-I sway blocks or no sway blocks at all, then you don't have proper sway control.  If it was fun to pull in LOW gear, I could have a John Deere.
Real pullers don't have speed limits.
If you can't make it GO... make it SHINY Dusty MI
Orange Level



Joined: 13 Sep
Location: Charlotte, Mi
Points: Post Options    Thanks(0)    Quote  Reply Posted: 28 Apr at 7:35am We had an A.C.  "C" that had the smaller PTO out put shaft.  917 H, '48 G, '65 D-10 series III "Allis Express" steve(ill)
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Joined: 11 Sep
Location: illinois
Points: Post Options    Thanks(0)    Quote  Reply Posted: 28 Apr at 9:44am the "original" B tractor and maybe some C were 1- 1/8 inch as Jay said ( the small shaft on the C might have been added over the years)... .Allis later standardized on the 1- 3/8 inch that everyone was using... all 540 RPM. Like them all, but love the "B"s. Fantrum
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Joined: 02 Feb
Location: Missouri
Points: 240 Post Options    Thanks(0)    Quote  Reply Posted: 28 Apr at 11:29am Thanks, everyone! I greatly appreciate the feedback.
I've heard of these bushings for the lift pins. I didn't originally like the idea of them because it's just another part to lose when it sits in storage, but I can find solutions for that... other than the kiddos wanting to play with it, ha!
I'll look into the sway blocks, as that's something I could definitely see making a difference.So would most tractors use the same length of PTO shaft? This is the part that still confuses me. I know PTO splines/diameters are universal between 540s and s (separately).. Although I didn't know the B/C had smaller shafts - so interesting!I'm looking to upgrade my garden plot this year, and even move it completely. I've looked into rear tine tillers and they're a bit expensive for my taste.. The used selection is kind of terrible as well. Alternatively, I can just buy a 3 point tiller for less and even accomplish more work with less effort. Definitely considering it! Just would prefer to not have to replace a PTO shaft (for correct length) if possible.Thanks again! Tbone95
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Joined: 31 Aug
Location: Michigan
Points: Post Options    Thanks(0)    Quote  Reply Posted: 28 Apr at 11:49am The measurement from the end of the PTO output shaft to the center of the draw pin, and the height of the shaft to the draw pin is a standard number.  The length of the drawbar depends on the implement, where it's support bearing is, to the next u-joint.  If the tractor shaft to pin measurements are correct, the shaft that comes with the implement should work.  If it's lost or something....You can try another shaft, just be certain it won't run out of stroke when you turn a tight corner or go into a dip, and be certain it won't pull apart when going over a hump. Fantrum
Silver Level Access



Joined: 02 Feb
Location: Missouri
Points: 240 Post Options    Thanks(0)    Quote  Reply Posted: 28 Apr at 12:19pm Thanks, Tbone. Much appreciated!

I guess my last question, and one I didn't have previously.. So it's likely unknown what the gearbox HP rating is on used equipment, understandably so. So let's just assume my 90HP+ is oversized. Shear pin is practically necessary on the implement, but it doesn't have one on this tiller I'm looking at.
Is the best solution to replace the PTO shaft on the implement then? I assume so, to get one with a shear pin. I know prices will vary widely, but is this pretty much a deal breaker or is it fairly affordable with a low budget? Oops. Another question. My bad. Fantrum
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Joined: 02 Feb
Location: Missouri
Points: 240 Post Options    Thanks(0)    Quote  Reply Posted: 28 Apr at 12:27pm Well, I think I found answers. Apparently many rotary tillers use a slip clutch instead of shear pins. Makes sense, now that I know it exists. Even if I did need to replace the entire tiller shaft assembly, they're pretty affordable. Thanks again everyone! Much appreciated! steve(ill)
Orange Level Access



Joined: 11 Sep
Location: illinois
Points: Post Options    Thanks(0)    Quote  Reply Posted: 28 Apr at 12:31pm our  bush hog mower has a shear pin... have a 5 ft tiller that has a splined shaff.. no shear pin.. we have used it that way for several years... If your tilling rocks and stumps it would not be a good idea... previous plowed field, or known grass field is doable. Like them all, but love the "B"s. Fantrum
Silver Level Access



Joined: 02 Feb
Location: Missouri
Points: 240 Post Options    Thanks(0)    Quote  Reply Posted: 28 Apr at 12:36pm Definitely rocks here in MO, lol.

This would be a previously untouched plot, so would definitely find some rocks. Heck, I dig 100lb rocks out of my front yard.. Guaranteed there's just as bad in the field. Les Kerf
Orange Level



Joined: 08 May
Location: Idaho
Points: Post Options    Thanks(0)    Quote  Reply Posted: 30 Apr at 10:29am steve(ill) wrote:

the "original" B tractor and maybe some C were 1- 1/8 inch as Jay said ( the small shaft on the C might have been added over the years)... .Allis later standardized on the 1- 3/8 inch that everyone was using... all 540 RPM.

I have personally owned three (3) Model C tractors and they all have the 1 1/8" PTO shafts; my current Model C is a unit.
PaulB wrote:

The problem of just swapping Cat-II pins or adding the bushings to a Cat-I implement and hooking it to a Cat-II tractor is; The Cat-I is 26" wide at the pins and Cat-II is 32" wide at the pins. You need the Cat-I sway blocks or no sway blocks at all, then you don't have proper sway control.  Going back to Paul’s point, you most likely can get by just removing one block if your cat 2 blocks have any wear. I put a ground down one on to use a cat 1 hitch bar that I only use for 1 job. Just make sure it doesn’t bind when lifting or will put extra wear one the joint eye’s.

Hello and welcome! If you’re a regular viewer of the Friday Parts buyer guides, you know we’re dedicated to helping you get the most out of your machinery. Today, we’re tackling a critical component that can be a real headache for many farmers and heavy equipment operators: selecting the right tractor PTO shaft. As our host highlighted, choosing incorrectly isn’t just an inconvenience; it can lead to costly failures and significant downtime, potentially “losing thousands of dollars every month.”

With competitive price and timely delivery, Jundi sincerely hope to be your supplier and partner.

Our customer service team often fields questions like, “Why does my Massey Ferguson PTO keep failing?” or “Why is my tractor underpowered after replacing the shaft?” The answer, in most cases, is surprisingly simple: the wrong tractor PTO shaft was chosen. This guide covers details that most videos won’t tell and will break down exactly what you need to know to make the right choice and keep your equipment running smoothly.

Why PTO Shaft Choice is Crucial

The lifespan and performance of your tractor PTO shaft aren’t random. There’s a logic to it, which can be summarized by a formula our expert shared:

“PTO shaft lifespan is approximately: Size Accuracy x Horsepower Compatibility / Usage Angle”

Let’s break down each of these variables, including some “hidden factors most videos won’t tell you about,” to ensure you make an informed decision.

1. Size Accuracy: “Close Enough” Isn’t Good Enough

This is the absolute foundation of selecting the correct tractor PTO shaft.

• The Danger of Incorrect Length: “Even an inch too short, that PTO shaft could snap clean off under load.” An incorrectly sized shaft will be overextended or overly compressed during operation, leading to immense stress on the yokes, U-joints, and the shaft tubing itself.
• Essential Measurements to Triple Check Before You Buy:
  1. Shaft’s Length (Center-to-Center at Shortest Position): Measure from the center of one U-joint to the center of the other U-joint when the tractor PTO shaft is fully compressed.
  2. Total PTO Shaft Length (Compressed): For the example shaft in the video, the “compressed length is 800 mm.” This is the overall length from end to end when fully closed.
  3. Extended Overall Length: This is the maximum safe operating length. For example, “the extended overall length is mm.” Exceeding this can cause the shaft to separate.
  4. Spline Inner Diameter: This refers to the measurement “inside the shaft grooves” on the yokes. It ensures the shaft correctly fits onto the tractor’s PTO output and the implement’s input shaft.

Key Measurement Points for a Tractor PTO Shaft:

Always provide these precise specifications to your supplier and “demand compliance.”

2. Horsepower Rating & Compatibility: Matching Power

The tractor PTO shaft must be robust enough to handle your tractor’s power output.

For more PTO Shaft Partsinformation, please contact us. We will provide professional answers.

Recommended article:
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• The 10-15% Buffer Rule: “Always pick a shaft rated 10 to 15% above your tractor’s power.” This safety margin accounts for peak loads and unexpected stresses.
• Example – Massey Ferguson (38HP Engine):
  • For this tractor, “a Series 4 shaft rated for 35 to 45 HP is your sweet spot.”
  • This “extra buffer keeps the drive shaft from grinding when loads spike.”
• Consequences of Under-Rating: An underrated tractor PTO shaft will be prone to twisting, U-joint failure, or complete breakage under normal operating conditions, especially when powering demanding implements.

Tractor PTO Horsepower Recommended Drive Shaft Horsepower 20-30HP 30-40HP 30-40HP 40-60HP 40-50HP 50-60HP 60-70HP 70-80HP 80-100HP Over 100HP

3. Connection Compatibility Aligns the Splines

Beyond just the diameter, the type of spline connection is vital.

• Ensuring Proper Alignment: “Make sure the splines and the connections align properly.” Different tractors and implements use different spline counts and profiles.
• Example – Massey Ferguson : This model “may require a 1 and 3/8 inch, six-spline connection.” This is a very common size for many agricultural tractors, but always verify for your specific equipment.
• Common Spline Types:
  • 1 3/8″ – 6 Spline: Very common for tractors up to around 70-80 HP.
  • 1 3/8″ – 21 Spline: Often found on higher horsepower tractors and more demanding implements.
  • 1 3/4″ – 20 Spline: Used for very high horsepower applications.
  • Other, less common types also exist.

Using a tractor PTO shaft with mismatched splines can lead to rapid wear of both the shaft yoke and the tractor/implement shaft, poor power transfer, and potential shearing of the splines.

4. Usage Angle is the Hidden Factor

While not a selection criterion for the shaft itself in terms of part number, the intended operating angle is crucial for the longevity of any tractor PTO shaft and is part of the lifespan formula.

• Ideal Operation: PTO shafts are designed to operate most efficiently and with the least wear when they are as straight as possible.
• Increased Angle = Increased Stress: As the operating angle of the U-joints increases (e.g., during tight turns or when working on uneven terrain), the stress on the U-joints and yokes increases significantly. This also causes fluctuations in rotational speed, which can vibrate the implement.
• Constant Velocity (CV) Shafts: For applications requiring consistently large operating angles, a CV tractor PTO shaft is often recommended. These have a special double U-joint design that helps to cancel out speed fluctuations and reduce stress at higher angles. While more expensive, they can be essential for certain implements like round balers or mowers that require tight turns while the PTO is engaged.

5. Choose a Tractor PTO Shaft with a Sturdy Guard

“Safety is paramount. Always choose a tractor PTO shaft with a sturdy guard to prevent accidents.”
The guard (usually a plastic shield) covers the rotating shaft, preventing clothing, limbs, or anything else from getting entangled. Ensure the guard is intact, rotates freely with the shaft (if designed to do so), and that the safety chains are properly attached to prevent the guard from spinning with the shaft itself.

Essential Maintenance for Your Tractor PTO Shaft

“Regular maintenance and inspections are crucial for smooth shaft operation.” A well-maintained tractor PTO shaft is safer and will last much longer.

Regular Lubrication:

Grease the U-joints according to the manufacturer’s recommendations (often every 8-10 hours of use, or daily). Use a good quality grease.

• • Some shafts also have grease points for the telescopic sections (the sliding inner and outer tubes).

Inspect the Guard:

• • Check for cracks, breaks, or missing pieces. Replace a damaged guard immediately.
  • Ensure the safety chains are attached and functioning.

Check U-Joints:

• • Look for any signs of wear, such as looseness, rust, or noise. Worn U-joints should be replaced promptly.

Inspect Yokes and Tubing:

• • Check for cracks, bends, or excessive wear on the yokes and the shaft tubing.

Ensure Smooth Telescoping:

• • The shaft sections should slide smoothly. If they bind, clean, and lubricate them.

Secure Connections:

• • Always make sure the tractor PTO shaft is securely locked onto both the tractor and the implement. Check locking pins or collars.

“Want to learn about tractor PTO shaft maintenance and installation? Check out our 5-minute fix library series,” suggests our host.

Conclusion

Understanding and correctly maintaining your tractor’s PTO shaft is key to enhancing your tractor’s performance, ensuring safety, and achieving a successful operational season. By paying close attention to size, horsepower rating, spline compatibility, and regular upkeep, you can avoid costly mistakes and keep your machinery in prime condition. If you’re in need of a high-quality replacement tractor PTO shaft or any other parts for your heavy equipment, we at Fridayparts offer a vast inventory of aftermarket tractor solutions. Our commitment is to provide top-notch products at affordable prices, with wide compatibility for many major brands. Fix it once, fix it right with Fridayparts!

For more information, please visit Cardan Shaft Manufacturer.