B7100 HST 4wd swash plate stop bolt

[Tnkubotaguy]

I mistakenly removed the swash plate stop bolt thinking it was a drain plug. The bolt will not go back in as the swash plate has hole that needs to be aligned. Does anybody know how to move the swash plate forward or rear to make the hole visible and thus allow the bolt to screw up and in to the alignment hole?
Thanks

 

[number two]

I've been following your thread on TBN.
Good Luck with your issue!

 

[arto98607]

I mistakenly removed the swash plate stop bolt thinking it was a drain plug. The bolt will not go back in as the swash plate has hole that needs to be aligned. Does anybody know how to move the swash plate forward or rear to make the hole visible and thus allow the bolt to screw up and in to the alignment hole?
Thanks

The HST should be removed and dismantled in order to do proper repair.

 

[Tnkubotaguy]

The HST should be removed and dismantled in order to do proper repair.

Okay let's assume I removed, dismantled and repaired (since there is nothing wrong with it) and now I have reinstalled it...how do I move the swash plate to align the hole in it with the stop bolt?

The HST should be removed and dismantled in order to do proper repair.

 

[arto98607]

Okay let's assume I removed, dismantled and repaired (since there is nothing wrong with it) and now I have reinstalled it...how do I move the swash plate to align the hole in it with the stop bolt?

I have dismantled and reassembled one Kubota HST of different model, but in general the pistons inside the HST motor cylinder block are spring loaded in order to get the initial seal in-between rotating cylinder bloc and valve plate.
This spring-loading is pushing the thrust plate away and preventing you from aligning the thrust plate hole for the stop bolt.
When it's disassembled there is no spring loading and you can reinstall the stop bolt.

There is plenty wrong with your HST now:

You may need to custom make a new proper stop bolt to fit your buggered re-threaded hole in the aluminum housing, or better yet get a replacement housing.
New stop bolt in manually re-threaded hole may not be perfectly straight and cause problems sooner or later ?

I would start looking for a used replacment HST if the rest of the tractor is in good condition and would not recommend installing a new bolt made in bench grinder in case you plan on keeping the tractor!

 

[whitetiger]

Okay let's assume I removed, dismantled and repaired (since there is nothing wrong with it) and now I have reinstalled it...how do I move the swash plate to align the hole in it with the stop bolt?

Moving the hydro pedal moves the swashplate. If that does not aline it, the hydrostat will need to be removed, disassembled, correctly reassembled, and reinstalled.

 

[Tnkubotaguy]

It may move the top variable one but not the bottom fixed swash plate. Are you sure?

 

[arto98607]

It may move the top variable one but not the bottom fixed swash plate. Are you sure?

No he is not, you are 100% right and that's why on this HST the bottom (motor) one is called 'Fixed swash plate" according to the manual.
The "thrust plate" I mentioned in post #5 above is just a flat plate in-between fixed swash plate and the fixed displacement motor pistons.

I.e.
The pump on the input shaft is variable displacement pump in which the volume is controlled by the pedal moving the swash plate, and the motor on the output shaft is a fixed displacement motor.

 

[Henro]

No he is not, you are 100% right and that's why on this HST the bottom (motor) one is called 'Fixed swash plate" according to the manual.
The "thrust plate" I mentioned in post #5 above is just a flat plate in-between fixed swash plate and the fixed displacement motor pistons.

I.e.
The pump on the input shaft is variable displacement pump in which the volume is controlled by the pedal moving the swash plate, and the motor on the output shaft is a fixed displacement motor.

OK. Not understanding the specifics of the system I still want to ask a question.

It looks like that stop bolt holds the bottom of the swash plate in position, and that the swash plate tilts one way or the other as the directional pedal is pressed. And there must be a spring somewhere to cause a swatch plate to go back to center when the directional pedal is released.

(Does the swash plate plate not tilt? My impression is that it does. Guess I need to do some more reading...)

If that’s the case and the stop bolt is removed, what’s to keep the whole assembly from sliding back-and-forth when the directional paddle is pushed? And if it does move, isn’t it possible that it might shift enough, so the hole in the swash plate came back over the hole in the case where the bolt goes up?

I think that possibility is what whitetiger (a highly experienced Kubota tech by the way) in referring to. Just my impression; I certainly cannot speak for him...

 

[arto98607]

Please reread posts #5 & #8, the answers are already there.


The top swash plate is part of the HST pump and it tilts as the pedal is pushed.
The bottom swash plate is part of the HST motor and does not tilt when pedal is pushed.

 

[Henro]

Please reread posts #5 & #8, the answers are already there.


The top swash plate is part of the HST pump and it tilts as the pedal is pushed.
The bottom swash plate is part of the HST motor and does not tilt when pedal is pushed.

OK, then humor me a bit…since removing that bolt allowed things to shift, I assume due to spring action of some sort, why would pushing on the directional pedal not counter whatever force caused the shift to begin with? At least to some degree.

Posts #5 and #8 may be clear to you…but maybe not to many of us reading them….

 

[arto98607]

OK, then humor me a bit…since removing that bolt allowed things to shift, I assume due to spring action of some sort, why would pushing on the directional pedal not counter whatever force caused the shift to begin with? At least to some degree.

Posts #5 and #8 may be clear to you…but maybe not to many of us reading them….

Because the pedal is not connected to the bottom (or motor) swash plate at all - instead it is connected to the top (or pump) swash plate.

I lost count, but that's been said now many times in this thread.

That's pretty funny eh?

 

[Henro]

Because the pedal is not connected to the bottom (or motor) swash plate at all - instead it is connected to the top (or pump) swash plate.

I lost count, but that's been said now many times in this thread.

That's pretty funny eh?

So if nothing is holding the bottom of the assembly, and force is applied to the top of the assembly, what keeps the bottom of the assembly from moving when that bolt is not there?

Seems obvious that bolt is there to keep the bottom from moving, and if not there the bottom likely would move…or the bolt would not be there to begin with.

Obviously, the bottom does move, since the hole the bolt goes into on the swash plate is no longer lined up with the threaded hole in the case.

Saying something multiple times without specific reasons why doesn’t help much.

Specifically, if the swash plate moved after that bolt was removed, why would one expect it to be locked into a different position never to move again?

 

[arto98607]

So if nothing is holding the bottom of the assembly, and force is applied to the top of the assembly, what keeps the bottom of the assembly from moving when that bolt is not there?

Seems obvious that bolt is there to keep the bottom from moving, and if not there the bottom likely would move…or the bolt would not be there to begin with.

Obviously, the bottom does move, since the hole the bolt goes into on the swash plate is no longer lined up with the threaded hole in the case.

Saying something multiple times without specific reasons why doesn’t help much.

Specifically, if the swash plate moved after that bolt was removed, why would one expect it to be locked into a different position never to move again?

It is explained in post #5 above, this is what it says:

HST motor cylinder block are spring loaded in order to get the initial seal in-between rotating cylinder bloc and valve plate.
This spring-loading is pushing the thrust plate away and preventing you from aligning the thrust plate hole for the stop bolt.
When it's disassembled there is no spring loading and you can reinstall the stop bolt.


In post #8 above I said this:

The "thrust plate" I mentioned in post #5 above is just a flat plate in-between fixed swash plate and the fixed displacement motor pistons.

 

[whitetiger]

It may move the top variable one but not the bottom fixed swash plate. Are you sure?

The bottom section of the hydro is the PUMP and has the variable swashplate, the MOTOR is in the upper section of the hydro and has no removable swashplate. It has a bearing that sets in a ramp which is cast in the housing.

 

[whitetiger]

Because the pedal is not connected to the bottom (or motor) swash plate at all - instead it is connected to the top (or pump) swash plate.

I lost count, but that's been said now many times in this thread.

That's pretty funny eh?

What's pretty funny is the fact that several times you have stated that the PUMP is at the top and the MOTOR is at the bottom which is false.
The PUMP is on the bottom shaft and has a link that moves the swashplate. The MOTOR has no removable swashplate as it is cast in the cover. See the attached pdf.

In reference to your " No he is not " comment in post #8, the correct response should have been, Yes he is.

I still have not seen any reference to what bolt it is the OP is even referring to.

 

[Tnkubotaguy]

Sorry, but it's number 15 in the diagram. Well...at least I'm not the only one confused here and hate that I am causing so much grief all over a little bolt. It appears I'm going to have to remove the HST as a unit, so I can get at the pistons which I cannot compress with a screwdriver up through the now 7/16" hole as apparently the pistons have oil in them that's not going to compress. So, with that I will attempt a disassembly and get to the bottom of this. I'm not much of a photographer as I just want to get it done but for the poor basted who ever removes the stop plug in the future thinking it was a drain plug like me, the answer will save weeks of worry. So far I got about $2 and 3 days of trying to figure this repair out.

 

[Henro]

Sorry, but it's number 15 in the diagram. Well...at least I'm not the only one confused here and hate that I am causing so much grief all over a little bolt. It appears I'm going to have to remove the HST as a unit, so I can get at the pistons which I cannot compress with a screwdriver up through the now 7/16" hole as apparently the pistons have oil in them that's not going to compress. So, with that I will attempt a disassembly and get to the bottom of this. I'm not much of a photographer as I just want to get it done but for the poor basted who ever removes the stop plug in the future thinking it was a drain plug like me, the answer will save weeks of worry. So far I got about $2 and 3 days of trying to figure this repair out.

Hope you get the tractor going again soon. Please do report on how it went for you.

I am going to stop asking questions and try to do a little reading on Kubota HST drives.

In the meantime, if I were a betting man I would put my money on Whitetiger as the one who knows how Kubota tractors work...

 

[whitetiger]

Hope you get the tractor going again soon. Please do report on how it went for you.

I am going to stop asking questions and try to do a little reading on Kubota HST drives.

In the meantime, if I were a betting man I would put my money on Whitetiger as the one who knows how Kubota tractors work...

I have had approx 100 hydros apart of various brands and styles ranging from zero turn mower to combines and large articulated front end loaders so I am getting acquainted with them.

 

[rbargeron]

(OP has changed tractor model - see later posts)