HST ? improved over the years

[dfkrug]

Dave,

I have a hard time imaging pumping action without an inlet port and outlet port. I have also looked at some axial pump design same as article below suggests. They do mention a valve plate. The rotation of cylinder block against the valve plate seems to me emulate suction and pressure cycle when the cylinder block rotate passed inlet opening(suction) or outlet opening (pressure). You may be able to say there is no valving but I think the function of valving is archived thru rotation of cylinder block against stationary valve plate.

JC,

Axial piston pump - Wikipedia, the free encyclopedia

If you look at Figure 8 that WIKI refers you to, you will see that the
inlet and outlet ports are always open. No valving. (Other than the
pressure reliefs on both ports.)

With respect to the end plates of the axial piston pump and motor, I do not know why they
are called "valve plates". Perhaps someone with more experience with HSTs on TBN can
comment. Seems to me, to be a "valve", you have to affect the flow in some way and
I do not see a poppet, spool, ball, gate, needle, or reed in the end plate. Just slots.

 

[JC-jetro]

If you look at Figure 8 that WIKI refers you to, you will see that the
inlet and outlet ports are always open. No valving. (Other than the
pressure reliefs on both ports.)

With respect to the end plates of the axial piston pump and motor, I do not know why they
are called "valve plates". Perhaps someone with more experience with HSTs on TBN can
comment. Seems to me, to be a "valve", you have to affect the flow in some way and
I do not see a poppet, spool, ball, gate, needle, or reed in the end plate. Just slots.

I my line of work any time you slow, increase or stop a flow (gas or fluid) with a device, that device can be called a valve, or regulating mechanism. I think in hyd pump or motor as the cylinder block rotates against a specially perforated plate you can call it a valve becuase that action modulate flow from zero to something and back to zero. I think due to such a close tolerance between plate, cylinder block and oil film make for a very tight seal enabling the whole thing to cause lots of pressure and flow.

JC,


JC<

 

[dfkrug]

I my line of work any time you slow, increase or stop a flow (gas or fluid) with a device, that device can be called a valve, or regulating mechanism. I think in hyd pump or motor as the cylinder block rotates against a specially perforated plate you can call it a valve becuase that action modulate flow from zero to something and back to zero. I think due to such a close tolerance between plate, cylinder block and oil film make for a very tight seal enabling the whole thing to cause lots of pressure and flow.
<

There are no moving parts to the end plate of a HST pump or motor; it
merely acts as a passageway for the oil going in or out. If a label is needed,
it would be more accurate to call it a manifold. All modification of the oil
flow is performed by the action of the pistons going in and out of the
cylinder block, which is varied by the mechanical tilting of the swash plate
by an external lever.

 

[john_bud]

I my line of work any time you slow, increase or stop a flow (gas or fluid) with a device, that device can be called a valve, or regulating mechanism.


JC<

Per your definition, the swash plate is the valve in the HST system. As it controlls the flow and flow volume.


So, what gear machine are you looking at getting?

jb

 

[jinman]

I my line of work any time you slow, increase or stop a flow (gas or fluid) with a device, that device can be called a valve, or regulating mechanism. I think in hyd pump or motor as the cylinder block rotates against a specially perforated plate you can call it a valve becuase that action modulate flow from zero to something and back to zero. I think due to such a close tolerance between plate, cylinder block and oil film make for a very tight seal enabling the whole thing to cause lots of pressure and flow.

JC, maybe this link wil help. It clearly shows "valveless" ports in the HST pump. There is no valve needed because a given set of pistons rotate past the inlet port and directly to the outlet port just as their function changes from suction to pressure. If you want to call that tiny flat spot between the inlet and outlet ports a "valve," and it helps you understand, then I have no problem with that.

HST Pump

 

[PA hayseed]

Slackdaddy -

Did you get enough information yet about HST?

 

[JC-jetro]

Per your definition, the swash plate is the valve in the HST system. As it controlls the flow and flow volume.


So, what gear machine are you looking at getting?

jb

John and Dave

Per definition (not myself) cylinder block against stationary valve plate or may be more appropriately called "manifold plate" emulate the function of a valve. I don't believe I said the swash plate is a valve. If it came to you that way it was not my intent.

Dave, My understanding is that the cylinder block rotates both in case of hyd motor and pump. swash plate angle can be either fixed or variable. Do you disagree with that?


John,

I have no personal animosity against HST and it is great. I still firmly believe if I had two tractor of exact same specs and had used it less than 30 hrs a year the gear tractor would be more reliable if it sat in a barn for 10 years without an oil change, specially if the tractor needs would be for occasional tilling and brush hugging without any loader work. For my taste I'd rather have a synchronized gear tractor with main dry clutch and hydraulic wet multi disk clutch for PTO. If I get the main clutch for a utility class with Multi-disk wet clutch then so much the better.

If I were to make money and use the tractor every day HST will win it for me in a heart beat.. I ain't making money in this ...I'm just having fun .. That's all.

JC,

 

[Slackdaddy]

Slackdaddy -

Did you get enough information yet about HST?

I think most of the posters visited: WWW.BigWordsSlackdaddyDoesNotKnow.com

Yeah, but I realy just wanted to know if the new HST CUTs where "herky jerky".

Seriously, I am going to have to take a day and go try some out at the dealers.

Slack

 

[JC-jetro]

JC, maybe this link wil help. It clearly shows "valveless" ports in the HST pump. There is no valve needed because a given set of pistons rotate past the inlet port and directly to the outlet port just as their function changes from suction to pressure. If you want to call that tiny flat spot between the inlet and outlet ports a "valve," and it helps you understand, then I have no problem with that.

Hi Jim,

Thanks for the link and chiming in. HST pump is a type of Positive Displacement pump unlike a Centrifugal pump. In centrifugal pump you would not need inlet and outlet valving, it it the matter of getting the fluid in the inlet volute of pump casing and slinging out. In case of HST pump The rotation of cylinder block against the valve plate does provide for the separation of suction and discharge cycle. I call it valving no different than opening of the faucet to wash my hand and closing it when I'm done.

I think we are mainly talking semantic here and this is like I say "tomatoe" and you say 'tomato"...

believe me I'd love to have a HST TLB for playing with dirt and a good gear tractor for ground engaging farming like tasks. They have a niche market.


JC,

 

[JC-jetro]

I think most of the posters visited: WWW.BigWordsSlackdaddyDoesNotKnow.com

Yeah, but I realy just wanted to know if the new HST CUTs where "herky jerky".

Seriously, I am going to have to take a day and go try some out at the dealers.

Slack

Sorry slack<

I know this this is a beaten to death horse I just wanted to double make sure it is dead alright

JC,