Can the hydraulic system get air locked after a fluid change

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Yes, there is a conventional dry clutch. You can see it on post #66. It's there for the PTO. You don't really need a clutch to change ranges on an HST. Many HST tractors are like this.

I'll add a picture from the parts catalogue as well:

View attachment 2700416

Ok. Thanks for that.
I’ll never land a job at a Kioti dealership l see.

 

[ptsg]

Ok. Thanks for that.
I’ll never land a job at a Kioti dealership l see.

That's what lets you engage or disengage the PTO.

I would say, at one point or another, just about all manufacturers had least one model with the same system.

In more recent years, most of them ditched the dry clutch and use a wet clutch for the PTO instead.

 

[Leonard malone]

It does have a clutch pedal that you have to depress to start the engine. If you were to push it in while moving the tractor would roll as if In neutral.you use it also to change from low to high range.

 

[arrow]

That's what lets you engage or disengage the PTO.

I would say, at one point or another, just about all manufacturers had least one model with the same system.

In more recent years, most of them ditched the dry clutch and use a wet clutch for the PTO instead.

So if the clutch pedal is controlling an actual clutch on these, how is the pressure being controlled on range changes. There’s got to be a relief valve some place or is it a dual function or pressure relief not needed?

 

[oldnslo]

What you talk about is fluid control. From what I’ve seen on my brand is an input shaft connected to the crank with gearing. If the engine is turning, so is the input shaft. If it is not, the gearing is either stripped, bearing compromised or attachment failed. The control, speed and direction of the tractor is happening after that with valve/fluid regulation.
Some even use that pedal as a brake mechanism as to disrupt fluid volume to relieve pressure. It is what makes range changes easier and also controls live ptos.
Are you the seeing the swash plate? I’ve heard that referred to as a clutch.
Why would an hst need fingers, pressure plate and clutch disc as a drive if it’s relying on regulated pressured fluid delivery to move?

Arrow
I am not repeat NOT talking about fluid control. The “dry” clutch is a pure mechanical link between engine and HST - transaxle assembly. The swash plate is part of the HST pump and yes it does provide fluid volume control and can be controlled in a multitude of ways from pure mechanical to electro proportional

 

[arrow]

It does have a clutch pedal that you have to depress to start the engine. If you were to push it in while moving the tractor would roll as if In neutral.you use it also to change from low to high range.

That has to happen as well if the pedal is controlling an actual valve.

 

[oldnslo]

So if the clutch pedal is controlling an actual clutch on these, how is the pressure being controlled on range changes. There’s got to be a relief valve some place or is it a dual function or pressure relief not needed?

Arrow
The dry clutch is NOT controlling any operation of the HST other than mechanical input power from engine. You are confusing mechanical input with hydraulic drive provided by the HST operation is like any other HST with charge pump, charge relief, forward and reverse relief etc.

 

[arrow]

Arrow
I am not repeat NOT talking about fluid control. The “dry” clutch is a pure mechanical link between engine and HST - transaxle assembly. The swash plate is part of the HST pump and yes it does provide fluid volume control and can be controlled in a multitude of ways from pure mechanical to electro proportional

In my case, common sense overcame stubbornness.
Apparently, there are several ways to skin the power transfer cat.

 

[oldnslo]

In my case, common sense overcame stubbornness.

Sometimes just can’t see the forest because there are too many trees in the way

Guilty of that myself more than once..

 

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Arrow
I am not repeat NOT talking about fluid control. The “dry” clutch is a pure mechanical link between engine and HST - transaxle assembly. The swash plate is part of the HST pump and yes it does provide fluid volume control and can be controlled in a multitude of ways from pure mechanical to electro proportional

So at the end of the clutch mechanism, there is no housing to control valve operation on these?
I’ve adjusted these plungers and when you do, it brings the clutch pedal inward.