B2650 PTO noise

[19thSF]

I didn't get much of a response, so I am going to try again. I am describing the PTP sound without an implement attached. I set the RPM to the lowest possible setting (around 1100 RPM). When I engage the rear PTO I get a loud continuous vibration or rattle seemingly coming from inside the trans-axle (if that is the correct nomenclature). The tractor has 90 hours, and I had not previously engaged the rear PTO. I do not own a three point implement at present, but buying a mower soon. The noise dissipates as the RPM is increased, and disappears somewhere around 2500 engine RPM. I have seen posts suggesting low RPM gear "slap" is to blame. If I have a problem, I would like to do something about it while the drive train warranty is still in force. Any thoughts?

 

[Eesquibel]

I didn't get much of a response, so I am going to try again. I am describing the PTP sound without an implement attached. I set the RPM to the lowest possible setting (around 1100 RPM). When I engage the rear PTO I get a loud continuous vibration or rattle seemingly coming from inside the trans-axle (if that is the correct nomenclature). The tractor has 90 hours, and I had not previously engaged the rear PTO. I do not own a three point implement at present, but buying a mower soon. The noise dissipates as the RPM is increased, and disappears somewhere around 2500 engine RPM. I have seen posts suggesting low RPM gear "slap" is to blame. If I have a problem, I would like to do something about it while the drive train warranty is still in force. Any thoughts?

My 2501 has a mild pto rattle as well at low RPMs. It’s brand new with just at 10hrs so I assumed it’s normal.

CURRAHEE!!

 

[19thSF]

My 2501 has a mild pto rattle as well at low RPMs. It’s brand new with just at 10hrs so I assumed it’s normal.

CURRAHEE!!

I never had the dubious pleasure of running up that mountain. I went through training at Fort Benning, GA.
They made up for it by making us run everywhere we went, that included doing the Airborne Shuffle to the latrine. I didn't walk once the whole time I was there.

 

[Eesquibel]

I never had the dubious pleasure of running up that mountain. I went through training at Fort Benning, GA.
They made up for it by making us run everywhere we went, that included doing the Airborne Shuffle to the latrine. I didn't walk once the whole time I was there.

I went to basic at Fort Benning. Cheers! Hopefully you get a response to your post. Anyway you can post a video of the rattle noise?

 

[MFFI422]

Also off topic. I've done a lot of O2 system work for the 19th out of Utah. Ex Freefall Instructor.

 

[SidecarFlip]

Back on topic... The pto reduction gears (you have a gearset in the rear cover to reduce the transfer shaft rpm to 540 at rated rpm, are straight cut, not helical), so there will always be a little gear lash.

 

[Eesquibel]

Back on topic... The pto reduction gears (you have a gearset in the rear cover to reduce the transfer shaft rpm to 540 at rated rpm, are straight cut, not helical), so there will always be a little gear lash.

Dont mean to jack this thread, but since we got an answer and are talking about rattles I got a question. I notice a slight rattle sound from maybe my rear axle, only in high and when going fast. It’s not super distinct, but if you really listen you can hear it. Is this also due to straight cut gears?

 

[19thSF]

Back on topic... The pto reduction gears (you have a gearset in the rear cover to reduce the transfer shaft rpm to 540 at rated rpm, are straight cut, not helical), so there will always be a little gear lash.

I would think that the gear lash would create some free movement of the PTO shaft. Does anyone any an idea how much free movement is acceptable?

 

[SidecarFlip]

Actually, at least on my M's, the 'freeplay (taking up the lash) is about 1/16" of the total rotation with another 1/4 turn before the built in pto brake locks the stub which most times isn't quite enough to get the mating coupler on an implement to engage the splines, so, I'll shut off the tractor and engage the pto, which releases the pto brake and allows me to rotate the stub shaft th align the splines with the implement coupler.

Some of my implements have over running clutches built in so rotating the pto shaft is no big deal as the freely rotate but others are fixed so I have to use the engage the pto (tractor off) method.

My bat wing chopper is direct drive (no over run clutch) and as a matter of operation, I put an overrunnig clutch on the pto stub before I hook it up.

Because the chopper freewheels as it winds down from operating speed, if I cut the throttle abruptly. the chopper is driving the pto and wearing on the internal brake so the external over running clutch ratchets as the chopper winds down while the tractor pto is not rotating.

Kubota's are noted for weak internal pto brakes, especially my M9's and to replace the brake entails a split. Not something I want to do so I use an external over running clutch. A hundred bucks is a lot cheaper than rebuilding the wet clutch pack inside the transmission.

I don't use it constantly, just with direct drive (no clutch) implements.

 

[SidecarFlip]

Having said that (above), my cab M9 has a 2 speed pto (540 and 1000) with exchangeable stubs. The 540 is 6 spline, the 1000 is 21 spine. Because the pto is a 2 speed, it has an extra set of straight cut gears in the carrier that is part of the back cover so it has a bit more lash (freeplay) in it, maybe an additional 1/16".

I use the 1000 rpm pto as an economy pto drive with a clamp on 21 to 6 spline adapter for running lower power implements at reduced engine rpm. My 1000 rpm pto will spin at 540 with the engine running at 1600 rpm versus 2250 for the 540 6 spline. I'm way below maximum torque output but it just sips fuel. Works well for raking or a grain leg where I don't need maximum pto torque. The engine won't produce enough torque to run say my round baler or disc mower.

 

[19thSF]

Having said that (above), my cab M9 has a 2 speed pto (540 and 1000) with exchangeable stubs. The 540 is 6 spline, the 1000 is 21 spine. Because the pto is a 2 speed, it has an extra set of straight cut gears in the carrier that is part of the back cover so it has a bit more lash (freeplay) in it, maybe an additional 1/16".

I use the 1000 rpm pto as an economy pto drive with a clamp on 21 to 6 spline adapter for running lower power implements at reduced engine rpm. My 1000 rpm pto will spin at 540 with the engine running at 1600 rpm versus 2250 for the 540 6 spline. I'm way below maximum torque output but it just sips fuel. Works well for raking or a grain leg where I don't need maximum pto torque. The engine won't produce enough torque to run say my round baler or disc mower.

Thank you SidecarFlip for the technical explanation!

 

[gmbc]

I didn't get much of a response, so I am going to try again. I am describing the PTP sound without an implement attached. I set the RPM to the lowest possible setting (around 1100 RPM). When I engage the rear PTO I get a loud continuous vibration or rattle seemingly coming from inside the trans-axle (if that is the correct nomenclature). The tractor has 90 hours, and I had not previously engaged the rear PTO. I do not own a three point implement at present, but buying a mower soon. The noise dissipates as the RPM is increased, and disappears somewhere around 2500 engine RPM. I have seen posts suggesting low RPM gear "slap" is to blame. If I have a problem, I would like to do something about it while the drive train warranty is still in force. Any thoughts?

If unit is under warranty I suggest taking it to Dealer to get it checked and repaired as soon as possible

 

[gmbc]

If unit is under warranty I suggest taking it to Dealer to get it checked and repaired as soon as possible

 

[damon.auto.tech7785]

If unit is under warranty I suggest taking it to Dealer to get it checked and repaired as soon as possible

Not sure if you Read the thread but it is a normal situation at low RPMS. PLus, you would not be running these implements at low rpms anyway. If you idle down you should be turning them off.

 

[Linstrum]

I have a B7100 direct drive with a 3 speed PTO I bought new in 1981. Without anything hooked-up to the PTO, it has quite noticeable gear slap with the PTO engaged in any of the 3 speeds and the engine at low idle. Because it has a tiny .75 liter three-cylinder engine, it runs awful rough at idle, exacerbating gear slap.

My L3400HST also makes pretty good gear slap with the PTO engaged and nothing hooked-up to the PTO. That's how I can tell when the neighbor kids have sneaked over and have been messing with it, besides the obvious seat down, throttle lever all the way back, and all the other knobs and levers where I didn't leave them. They haven't figured out how to get the loader control out of the float position, where I leave it. That, and how to release the backhoe seat to put it down into operating position.

That's a good reminder to drop the front end loader and backhoe. I haven't had any broken gauges yet, or any dirt or rocks in the fuel tank.