Tractor Shakes when PTO is engaged and RPMs are low

vft2003

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Kubota MX5100
Aug 6, 2021
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Sodapop1!
I have a MX5100 and recently I noticed that it shakes pretty bad when I engage the PTO with the RPMs all the way down and gets worse until about 1500 then it goes away. the Hydraulic fluid has been getting really hot too, IDK if this is the issue or something else but it gets so hot after a couple hours I don't feel comfortable running it. It has recently blown both power steering hoses because of this.
 

85Hokie

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Sounds like a PTO balance or balance at the blade issue - I am sure the PTO slides in ONLY one way, but if by chance if pulled apart the universal would have a wobble.

Have someone engage the pto - you lay a stick on top of the spinning pto ( I know this sounds crazy) does the stick bounce up and down?

Are the blades balanced on the mower? Could there be something attached to one of the blades under the mower? A bag? wire? Any of that would cause a vibration.

After a good bit of time - the hydraulic fluid WILL get hot ....... on a backhoe or FEL the cylinders often get so hot you cannot place your hand on them.
 
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RCW

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There seems to be 2 issues -- - PTO engagement and fluid temp.

Hokie has some good ideas related to the PTO engagement. I would bump the RPM up a little to engage...not from idle.

I have a bunch of questions related to the fluid temperature.

What model MX5100 do you have...there's 3 I think...?
This just popped up?
You had the tractor a while?
Where are you located?
Been really hot there?
What are you running with the PTO?
Rotary cutter/bush hog, baler?
Something that makes a lot of dust/chaff/seed?

I've read here on OTT that the HST on a tractor can often run ambient temperature plus 100F. Makes for some pretty hot fluid....

What transmission do you have - - geared or HST?
Does your MX5100 have an oil cooler?
Is it clean?
Have you ever used a laser infrared thermometer to check the temperature?

You say both power steering hoses blew due to hot fluid....

How do you know that was the cause?
Is the tractor stored outside, where sun damage might have an effect and weakened the hoses?

What hydraulic fluid is in it, and when was it last changed?

Trust me, not trying to be a smart ass.

Just trying to help you solve your problems.

There's some guys much smarter than me that can help, and they may have similar questions.
 
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Fordtech86

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If this is with a bush hog on the back, I would start with making sure the blades move pretty free. Blow out grass and debris that gets in there, spray some lube around the pin that attaches the blade (I just use wd40) and try it. Sounds like the blades sticking a bit. And of course, block the mower with jack stands, cinder blocks, wood etc before getting under it.
 
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BruceP

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Do you have another implement you could hook up and try the same thing?

This would tell you if the vibration is the tractor.... or the implement.

Also, if the PTO shaft has too much 'angle' in it... it may vibrate.
 
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vft2003

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Kubota MX5100
Aug 6, 2021
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Sodapop1!
Hey thanks for the responses. The tractor is a MX5100DT 4wd manual transmission. I bought it new 8 or 9 years ago. These problems just started seemingly at the same time. I’ve mowed all day long before and it not get hot. The wobble is without any implement attached. I checked the tranny temp with a laser thermometer last time I operated it for two hours and it was 215F. When I blew the first hose I changed the hydro fluid and filter and while I was at it I changed the engine oil and filter as well as the coolant. The day the first hose blew the engine temp was getting close to the red line which it had never done. So I shut it down and blew out the radiator which was clogged pretty good. I let it set for a while before I started mowing again. And about an hour later is when the steering hose blew. The engine temp has never got close to hot again after I cleaned the radiator.
 

airbiscuit

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The whole video is good but look at 2:00 - Out of Phase
 

Russell King

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Ok I have to ask for clarification again.

You have the tractor sitting with no implements attached to rear PTO (or mid PTO if it has one). You push clutch in and engage the rear PTO and release the clutch with the tractor in neutral and something shakes? What shakes? Does the whole tractor shake like the engine speed is really low? Does the PTO shaft out of the tractor shake?
 
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RCW

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vft2003.....let's regroup a little bit....

Tranny temp 215 degrees after 2 hours' work....Good for you to check it.

Sounds reasonable to me. Granted, a geared tractor, but after 2 hours of mowing, stuff is gonna get hot.

The engine was getting hot, and that's when the steering hydraulic lines blew...

Unrelated systems in the tractor. Coincidence is all I can think of....

Temperature improved after blowing out the radiator...

GREAT THING! GOOD FOR YOU! The number of tractors with cracked heads because radiators aren't cleaned out.....

If you're getting a "shake" engaging the PTO without anything attached....that could be a whole different issue.
 
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vft2003

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Kubota MX5100
Aug 6, 2021
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Sodapop1!
I guess I have bad info. It does it with anything attached but not when there is nothing attached. the whole tractor shakes until I increase the RPMs
 

RCW

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I guess I have bad info. It does it with anything attached but not when there is nothing attached. the whole tractor shakes until I increase the RPMs
That's not a bad thing. Look back at Hokie's recommendations...

We now know what the tractor is...what exactly is the mower you're running?
 

SDT

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I guess I have bad info. It does it with anything attached but not when there is nothing attached. the whole tractor shakes until I increase the RPMs
It is normal for the mower to vibrate/shake when engaging the PTO, especially if the blades have swung forward upon shutdown.

Always reduce engine RPM to idle before disengaging PTO. Never turn engine off with PTO engaged.

SDT
 
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vft2003

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Kubota MX5100
Aug 6, 2021
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Sodapop1!
I took it to the dealership yesterday and the mechanic hooked it up to the dyno and discovered the wobble. He suggested the counter shaft might be broke. A friend thinks maybe the PTO bearing is going bad or gear teeth are broke. What are your thoughts on these scenarios? I’m gonna run a disk for several hours today I’m curious to see if the hydro system will get just as hot when not operating the pto.
 

vft2003

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Kubota MX5100
Aug 6, 2021
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Sodapop1!
I
It is quite common for fluid temps to run ambient +100 degrees.
i.e. 80 F outside-180F fluid temp.
Good Luck!
It was probably close to 100 outside when I was operating. I read in several places it is not good for the hydro oil to get above 180.
 

SDT

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I took it to the dealership yesterday and the mechanic hooked it up to the dyno and discovered the wobble. He suggested the counter shaft might be broke. A friend thinks maybe the PTO bearing is going bad or gear teeth are broke. What are your thoughts on these scenarios? I’m gonna run a disk for several hours today I’m curious to see if the hydro system will get just as hot when not operating the pto.
"[C]ounter shaft might be broke....? What?

How would the PTO even work if an internal shaft was broken???

Based upon the limited information available in this thread and without first hand inspection, things sound normal to me.

SDT
 
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BruceP

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What are your thoughts on these scenarios?
It sounds to me as if you practice 'good' PTO engagement., (you engage at low RPM then slowly bring up to operating speed.) It is Extremely unlikely that something is broken.

However, bearings can 'go bad' at any time. (especially if their lube is overheated)

When I used to help out on the family dairy farm. They had HUGE JD tractors (all 4 wheels over 6ft tall...the rear wheels were dual on each side) they ALWAYS engaged at low RPM and slowly brought speed up. When you are talking about 100s of horsepower driving a corn-chopper, it is all too easy to twist a PTO shaft if care is not taken. (A corn-chopper takes 8ft tall cornstalks, chopps it into fingernail size bits then blows into dumptruck running to the side.... it is not hard to envision how much power this consumes with a 20ft swath.)

I took it to the dealership yesterday and the mechanic hooked it up to the dyno and discovered the wobble.
It is encouaging that they were able to duplicate the vibration. I understand that it is not easy to diagnose without some disassembly.
 

Henro

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I took it to the dealership yesterday and the mechanic hooked it up to the dyno and discovered the wobble. He suggested the counter shaft might be broke. A friend thinks maybe the PTO bearing is going bad or gear teeth are broke. What are your thoughts on these scenarios? I’m gonna run a disk for several hours today I’m curious to see if the hydro system will get just as hot when not operating the pto.
You might have stated it but if so I missed it. Is the clutch for the PTO hydraulic, and something you cannot control?

I ask because I had a similar issue with my VERY SMALL BX tractor. After years of living with significant sudden engagement at low RPM levels, I learned if I engage the PTO hat higher RPM it is MUCH smoother. Was counter intuitive for me. But is the way I do it now. Much more satisfying...
 

vft2003

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Kubota MX5100
Aug 6, 2021
12
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Sodapop1!
Yes the PTO clutch is hydraulic. I just ran the disk for several hours the transmission didnt get as hot the external temp was 165. Maybe y’all are right it’s all in my head and there is nothing to worry about
 
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vft2003

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Kubota MX5100
Aug 6, 2021
12
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Sodapop1!
There is definitely a problem. after running a brush hog for about an hour I touched the transmission and it was hot enough to burn me. I shut it down and spit on the transmission it immediately boiled off. It doesn't get hot like this when I'm not using the pto. The mechanic at the Kubota place thinks it's either the countershaft or countershaft bearing. The way he talks it would be a huge undertaking to get it apart to check this out. $$$$