Broke Hydrostat twice? Why?

[dfkrug]

I opened up the pressure test ports, seen here. Behind them was a double spool valve, all
removed to check for cleanliness. Very clean in there.

 

[dfkrug]

Then, the forward and reverse pressure relief valves were removed and checked for dirt,
or a fractured spring. These open at just under 5000psi, according to the manual. To
test them properly, you put a 10,000psi gauge on the left or right test port (see above)
and make the running tractor go to relief. I have the gauge and fitting here, but
have not had the oppy to do this test.

Both were clean and intact. The nut that holds it together is welded so someone (like
yours truly) does not easily adjust it. They look almost exactly like the RVs on my
Kioti.

Passage ways to the valve plates for both pump and motor were clear and clean.

 

[TSO]

Hanging on your every, above-my-head word LOL

Say... Dfkrug... Do you know who makes the HST unit in my Iseki built Massey 1648 by chance...?

 

[dfkrug]

Say... Dfkrug... Do you know who makes the HST unit in my Iseki built Massey 1648 by chance...?

I could not even guess who made it. I also never heard of the company who made this TYM unit.

BTW, I am a Spartan, lower right on your avatar...nice Sparty.

 

[TSO]

I could not even guess who made it. I also never heard of the company who made this TYM unit.

BTW, I am a Spartan, lower right on your avatar...nice Sparty.

Go Green & White!

Doesn't TYM make their own HST's?

And thx... Figured it was worth a shot. No one seems to know (our be willing to disclose) who makes the HST in mine. Figured with your exposure you may have had some insight.

 

[dfkrug]

Finally, the pump.

The maker is Tong Myung Heavy Industries, LTD. This is a South Korean maker of
industrial products, founded 1997. If you look closely, you can see one of the
splines on the input shaft is broken off. That is strange. Susanne may have a better
picture of that.

 

[dfkrug]

And here is our problem.

Looking at the pump's valve plate, you can see erosion of the metal next to one of
the ports. This is the area where oil is pumped by the pistons at maximum pressure
into the forward port. The reverse port would have sustained the same pressures,
but it got used far less than the forward port, so it was not damaged.

My conclusion is that the oil overheated and boiled at the place where you see the
metal erosion. This was likely caused by the AUX detent valve being ON for an
extended period (perhaps minutes), which forced the full output of the implement
pump through the system relief valve.

 

[dfkrug]

Here is an annotated photo of one of the fixed valve plates and the rotating cylinder
block. The ports in the valve plate experience flow in either direction, depending
on the tilt of the swash plate. For the motor, the swash plate is at a fixed angle,
so the direction of flow from the pump will determine which way it spins.

 

[crazyal]

Could the worn/ eroded parts be made by a machine shop? If so it seams like you could make it a working unit again and have a spare.

I would think about adding a temperature gauge to monitor the oil temp as well as a way to keep that lever from accidentally moving to a position to cause the hydro to go into bypass.

 

[McREBEL]

This has been a very interesting thread to follow. Thanks to Bob and dfkrug for sharing.

Now I wonder if this part can be purchased and, if so, for how much.