M9540/9960 PTO Brake Problems

SDT

Well-known member

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multiple and various
Apr 15, 2018
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SE, IN
New forum member here but longtime member elsewhere.

I own a 2015 M9960 ROPS 12 speed, used exclusively for mowing. Currently, I use a HD 7' mounted cutter but plan to replace this cutter with a 12 or 15 foot BW cutter within the next year. My tractor has about 46 hours on the meter.

Recently, I was at my local CNH/Kubota dealer, where I am a good customer and on first name basis with everyone there. I noticed an M9540 in the shop that was split for repair work. Upon inspection, I noticed catastrophic failure of the PTO brake. Being both lifetime mechanic and design engineer, I didn't like what I saw so I researched to see if the PTO brake in my M9960 was the same.

I learned that the PTO brake problem was a known issue and the entire PTO clutch/brake assembly had been redesigned during the M9960 model run. The new unit is more robust and may solve the issue. I say may because I viewed the replacement unit before the M9540 was reassembled, and, being a design engineer, remain skeptical. Further research, of course, revealed that my M9960 was built before the engineering change to the new, more robust design was put into production. None of you folks know me, but experience has taught me that I am not a so-called "lucky" person.

The issue in question involves dissipating the energy in a rotating PTO load once the PTO is turned off, which applies the PTO brake. The old PTO brake design (and, maybe the new design) is inadequate to do so, under conditions expected to be encountered in normal operation by most users. Such loads include rotary cutters.

Being both a mechanic and design engineer, I would never turn off the PTO with a connected inertial load without first reducing the engine RPM to idle. Indeed, I idle the engine and back the mower into uncut grass immediately upon turning the PTO off. That said, I can find no such instructions in my M9960 owners manual.

More troubling is the fact that the M9540 that I inspected had spent it's entire life operating a hydraulically driven boom mower. In this situation, the PTO drives only a high capacity hydraulic pump. There is little or no inertial load, yet this PTO brake failed catastrophically.

Of course, this M9540 was out of warranty on both elapsed time and, maybe, hours. IIRC, it had somewhere around 2,000 hours on the meter.

I was told by my dealer that Kubota paid none of the repair bill for this unit, even though the problem was a well known issue as evidenced by the redesign. I was told that the repair bill was around $3,500, nearly $1,000 of which was the cost of the replacement, redesigned PTO clutch/brake assembly.

I'm sold on Kubota, folks, but this troubles me, especially because I own a 46 hour M9960 with the old design PTO clutch/brake that will be long out of elapsed time warranty long before any such failure may occur.

Does anyone have additional information regarding this issue?

Thanks, in advance.

SDT
 
Last edited:

Gerry

New member
Aug 30, 2016
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0
New Zealand
I'm surprised your mower does not have a one-way clutch on the drive shaft. When the PTO is disengaged it stops turning and the mower just winds down in its own time.
 

lugbolt

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Equipment
ZG127S-54
Oct 15, 2015
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Yes.

The original pto clutch pack for the M-40 series is NLA, and superceded to the M-60 PTO clutch assembly. It's expensive. But it mostly solves the "issue".

"Issue" in quotes because it's my understanding that a very small percentage of the total number of M-40's had a problem with the clutch pack failure. This tells me that Kubota stepped up to the plate for a redesign. Also, I am not certain on this-but I "think" the warranty on the pto clutch was extended to 5 years (from the original 2)-so owners of M-40's could get another 3 years on the pto clutch. Also a "good will" from Kubota.

Car manufacturers do it ALL the time. They are the world's worst. Sometimes you can ascertain that a redesign was made by looking at the part number. Ford is easy to figure out. The basic part number, for instance, D4AE-6015 is an engine block. But most are D4AE-6015-AA, and the suffix determines how many times it was revised. A being #1 revision, AA being the 27th (goes A to Z then double letters). Yamaha's part numbering system is somewhat similar. If you actually look at the numbers, it's mind blowing how many times a part was changed....tells me that they found some issue, color, size, whatever, and updated it. Every manufacturer does it and they have a right to, and I'm glad they do it, so that we (consumers) get the most up-to-date part possible that might alleviate an issue that the original has/had.

It was explained to me that reducing engine speed back to near idle speed and allowing the implement speed to drop accordingly before turning off the pto STOPS the "problem". I have personally had to do a few of the M-40 PTO clutch packs and of them, after schooling the owner to reduce engine speed, they've never had a problem since. And they're all still using the original style PTO clutch pack...which was all that was available at the time of replacement. Only one of my customers got the 9960 style pack and he was NOT happy about the price of it-and I certainly don't blame him. I want to say it was about $2000 back then just for the part and that was the only way it was available. May have changed. That was about 3 years ago.

....and finally (and don't take it the wrong way), engineers tend to over-think things anyway, but IMO that is a good and bad thing. Engineers are required for about everything-and I respect that wholeheartedly-- but at the same time an engineer's way of thinking, or overthinking, causes headaches for both the engineer and their equipment and for the technicians who get to deal with 'em. And on that note, engineering mistakes are "generally" not considered a manufacturing defect and aren't usually warrantable until it's deemed broken by the manufacturer. In other words, they won't warranty it until it's broke and still within a warrantable period-even if it is a "bad design". Been there many times with many different types of machines-motorcycles being the worst because the owners tend to be tightly gathered and quite vocal amongst themselves, so if the words "bad design" get thrown around, I was the one (as a dealer) who got to try to explain to the person that if it ain't broke, it can't be fixed under warranty no matter how "bad" it is. Now if that consumer wanted it replaced and was willing to pay for it outside of warranty coverage, fine, but typically it would get replaced with the exact same part-unless there was an aftermarket part that addressed the "bad design"-which meant it was likely to do the same thing again... And honestly there weren't that many. The KLR650 guys called the balancer chain a "bad design" and in fact they lasted tens of thousands of miles if the owners manual was followed and the oil was changed-and the correct oil used (rare). What killed them was constantly driving down the freeways at 70-80 mph, big single cylinder engine running 5500 RPM continually, which it wasn't designed for-and was called out in the owner's guide. The other side effect of operation in those conditions was oil usage...same for the vulcan 2000...they use oil (normal) because of how they are used. Mule 4010's and 610's are another common deal, the oil level would rise due to moisture and fuel vapors in the oil building up....stemming from operators starting a cold engine, driving to the mail box at or just above idle speed, shut engine off, get mail, then start engine & drive back very slowly to the house. After a few cycles of the motor NEVER WARMING UP, it would "make oil"-and eventually start smoking and/or foul plugs, gum up the intake system, etc. Again, operator error but many a consumer called it a "bad design"....and it wasn't, it's a great design but the engine needs to get warm. The originally installed engine was a generator engine which ran at 3500 RPM all the time; and in the Mule, many get run at 1200-1800 RPM for very short periods....which it wasn't designed to do, so it never warms up to boil off any moisture/fuel vapors in the crankcase.


So why was a recall not issued for the M9540 clutch packs (or KLR650 chain tensioner or Mule engines)? Because it wasn't considered a safety issue. Recalls are safety related only. Factory directed modifications can be issued, however, to address something that isn't really safety related, they can be a fix-as-fail or they can be fix whether or not they've failed-all depends on what the manufacturer thinks is best for the consumer-and they don't necessarily have to be done and in fact many aren't done because consumers get a letter that says basically your stuff may fail, we will pay for an update, and the consumer proceeds to wipe his/her butt with it and then throw it away....and then as a tech, I get to hear about how badly designed it is--but I know in the back of my mind during the conversation that (X manufacturer) issued a fix-as-fail bulletin and a letter as such, yet consumer rolled it up and smoked it or whatever he/she decided was the best use for it at the time.
 

Tx Jim

Well-known member
Lifetime Member

Equipment
M7040 HDC-1,JD 4255,Ford 6700
Apr 30, 2013
1,176
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63
Coyote Flats,Texas
I'm surprised your mower does not have a one-way clutch on the drive shaft. When the PTO is disengaged it stops turning and the mower just winds down in its own time.
Do rotary cutters(brush/pasture) in Australia come with over-running clutch? I never seen a rotary cutter aka mower in the USA with an ORC.
 

SDT

Well-known member

Equipment
multiple and various
Apr 15, 2018
3,084
923
113
SE, IN
I'm surprised your mower does not have a one-way clutch on the drive shaft. When the PTO is disengaged it stops turning and the mower just winds down in its own time.
I'm unaware of any that do.

SDT
 

SDT

Well-known member

Equipment
multiple and various
Apr 15, 2018
3,084
923
113
SE, IN
Yes.

The original pto clutch pack for the M-40 series is NLA, and superceded to the M-60 PTO clutch assembly. It's expensive. But it mostly solves the "issue".

"Issue" in quotes because it's my understanding that a very small percentage of the total number of M-40's had a problem with the clutch pack failure. This tells me that Kubota stepped up to the plate for a redesign. Also, I am not certain on this-but I "think" the warranty on the pto clutch was extended to 5 years (from the original 2)-so owners of M-40's could get another 3 years on the pto clutch. Also a "good will" from Kubota.

Car manufacturers do it ALL the time. They are the world's worst. Sometimes you can ascertain that a redesign was made by looking at the part number. Ford is easy to figure out. The basic part number, for instance, D4AE-6015 is an engine block. But most are D4AE-6015-AA, and the suffix determines how many times it was revised. A being #1 revision, AA being the 27th (goes A to Z then double letters). Yamaha's part numbering system is somewhat similar. If you actually look at the numbers, it's mind blowing how many times a part was changed....tells me that they found some issue, color, size, whatever, and updated it. Every manufacturer does it and they have a right to, and I'm glad they do it, so that we (consumers) get the most up-to-date part possible that might alleviate an issue that the original has/had.

It was explained to me that reducing engine speed back to near idle speed and allowing the implement speed to drop accordingly before turning off the pto STOPS the "problem". I have personally had to do a few of the M-40 PTO clutch packs and of them, after schooling the owner to reduce engine speed, they've never had a problem since. And they're all still using the original style PTO clutch pack...which was all that was available at the time of replacement. Only one of my customers got the 9960 style pack and he was NOT happy about the price of it-and I certainly don't blame him. I want to say it was about $2000 back then just for the part and that was the only way it was available. May have changed. That was about 3 years ago.

....and finally (and don't take it the wrong way), engineers tend to over-think things anyway, but IMO that is a good and bad thing. Engineers are required for about everything-and I respect that wholeheartedly-- but at the same time an engineer's way of thinking, or overthinking, causes headaches for both the engineer and their equipment and for the technicians who get to deal with 'em. And on that note, engineering mistakes are "generally" not considered a manufacturing defect and aren't usually warrantable until it's deemed broken by the manufacturer. In other words, they won't warranty it until it's broke and still within a warrantable period-even if it is a "bad design". Been there many times with many different types of machines-motorcycles being the worst because the owners tend to be tightly gathered and quite vocal amongst themselves, so if the words "bad design" get thrown around, I was the one (as a dealer) who got to try to explain to the person that if it ain't broke, it can't be fixed under warranty no matter how "bad" it is. Now if that consumer wanted it replaced and was willing to pay for it outside of warranty coverage, fine, but typically it would get replaced with the exact same part-unless there was an aftermarket part that addressed the "bad design"-which meant it was likely to do the same thing again... And honestly there weren't that many. The KLR650 guys called the balancer chain a "bad design" and in fact they lasted tens of thousands of miles if the owners manual was followed and the oil was changed-and the correct oil used (rare). What killed them was constantly driving down the freeways at 70-80 mph, big single cylinder engine running 5500 RPM continually, which it wasn't designed for-and was called out in the owner's guide. The other side effect of operation in those conditions was oil usage...same for the vulcan 2000...they use oil (normal) because of how they are used. Mule 4010's and 610's are another common deal, the oil level would rise due to moisture and fuel vapors in the oil building up....stemming from operators starting a cold engine, driving to the mail box at or just above idle speed, shut engine off, get mail, then start engine & drive back very slowly to the house. After a few cycles of the motor NEVER WARMING UP, it would "make oil"-and eventually start smoking and/or foul plugs, gum up the intake system, etc. Again, operator error but many a consumer called it a "bad design"....and it wasn't, it's a great design but the engine needs to get warm. The originally installed engine was a generator engine which ran at 3500 RPM all the time; and in the Mule, many get run at 1200-1800 RPM for very short periods....which it wasn't designed to do, so it never warms up to boil off any moisture/fuel vapors in the crankcase.


So why was a recall not issued for the M9540 clutch packs (or KLR650 chain tensioner or Mule engines)? Because it wasn't considered a safety issue. Recalls are safety related only. Factory directed modifications can be issued, however, to address something that isn't really safety related, they can be a fix-as-fail or they can be fix whether or not they've failed-all depends on what the manufacturer thinks is best for the consumer-and they don't necessarily have to be done and in fact many aren't done because consumers get a letter that says basically your stuff may fail, we will pay for an update, and the consumer proceeds to wipe his/her butt with it and then throw it away....and then as a tech, I get to hear about how badly designed it is--but I know in the back of my mind during the conversation that (X manufacturer) issued a fix-as-fail bulletin and a letter as such, yet consumer rolled it up and smoked it or whatever he/she decided was the best use for it at the time.
I always reduce engine speed to idle before turning off the PTO on any tractor with a PTO brake and have done so for decades. Common sense for anyone mechanically inclined.

Most troubling issue with the M9540 that I saw in my dealers shop is this tractor had never driven a rotary cutter. It has spent it's entire life with a hydraulically powered boom (bank) mower. The PTO has never been connected to anything but a hydraulic pump, yet the PTO brake failure was catastrophic.

Troubling.

SDT
 

Tx Jim

Well-known member
Lifetime Member

Equipment
M7040 HDC-1,JD 4255,Ford 6700
Apr 30, 2013
1,176
117
63
Coyote Flats,Texas
I always reduce engine speed to idle before turning off the PTO on any tractor with a PTO brake and have done so for decades. Common sense for anyone mechanically inclined.

Most troubling issue with the M9540 that I saw in my dealers shop is this tractor had never driven a rotary cutter. It has spent it's entire life with a hydraulically powered boom (bank) mower. The PTO has never been connected to anything but a hydraulic pump, yet the PTO brake failure was catastrophic.

Troubling.

SDT
DITTO when operating rotary mower idle engine for a little while before disengaging pto.
 

Gerry

New member
Aug 30, 2016
4
0
0
New Zealand
Do rotary cutters(brush/pasture) in Australia come with over-running clutch? I never seen a rotary cutter aka mower in the USA with an ORC.
I don't know about Australia, but in New Zealand they do. I used to have a twin drum mower with no over-run clutch on my Ford 5000. Needless to say the PTO brake did not work for long. I would say an un-clutched mower of any reasonable size would wreck any PTO brake no matter what brand of tractor.
The one way mechanism is housed in the last part of the yoke on the drive shaft nearest the mower spindle. It is a series of ball bearings in a groove. Drives one way but not the other. Keep it greased and they go for years. They make a clicking sound when the PTO is disengaged and the mower rotors are running down.
 

lugbolt

Well-known member

Equipment
ZG127S-54
Oct 15, 2015
4,807
1,575
113
Mid, South, USA
I always reduce engine speed to idle before turning off the PTO on any tractor with a PTO brake and have done so for decades. Common sense for anyone mechanically inclined.

Most troubling issue with the M9540 that I saw in my dealers shop is this tractor had never driven a rotary cutter. It has spent it's entire life with a hydraulically powered boom (bank) mower. The PTO has never been connected to anything but a hydraulic pump, yet the PTO brake failure was catastrophic.

Troubling.

SDT

Well....I see opportunity. You're an engineer, engineer a way to fix it, then market your device if it's that troubling. Maybe you could help others who are also troubled by this "bad design"?