More torque for my Power trac?

[SnowRidge]

Snowridge,

Do you have the Danfoss series 15 VSP pump?

It's a Danfoss Series 15VP.

 

[SnowRidge]

From some Danfoss sales literature concerning hydrostatic drive products of all sizes:

The closed circuit piston pump is normally factory
equipped with a charge pump, charge pressure
relief valve, and a control. It may also be equipped
with high pressure protection devices such as relief
valves or pressure limiters. A loop flushing
shuttle valve can be integral to the pump or motor, or
may be installed externally. Other components such
as the reservoir, heat exchanger, and filter are added

Emphasis added.

 

[SnowRidge]

There has to be a relieve valve. Reasoning is...

If the pump is built tight enough to create 2500 PSI, and is direct drive, then when the pump hits an imoveable object (ie oil with no place to go) the engine and pump stop dead. The oil has no place to go and that sudden shock will cause an explosion, not a bog.

It isn't direct drive, in that there are six hydraulic hoses involved, which have some shock absorbing qualities. Be that as it may, Sauer Danfoss also builds an integrated version of the same hydrostatic pump. It has the pump and drive motor in the same case. The engine input shaft is on one end, and the drive output shaft is on the other. There are no hydraulic hoses at all in the high pressure circuit.

It doesn't have a high pressure relief valve, either.

These are low horsepower systems. It looks like the design is simply rugged enough to absorb the occasional shock of excessive loading.

Relief valves are essential on the other systems. Without them, the machine would be unusable. Imagine having your engine stall each time your steering reached lock, or when you ran the tilt to its limits, or if an implement suddenly froze up, which actually happened to me. Unlike the tram circuit, reliefs on those circuits are required. They simply have to be there.

Even if it would be nice to have high pressure reliefs in the tram circuit, PT would never spend the money to put them on. Power Trac doesn't do nice.

 

[ponytug]

Stray,

Not to get your goat, but this might help you;

M561 Gamma goat, 6 wheel hydraulic drive...103HP, floats...

All the best,

Peter

 

[J_J]

SnowRidge.

Since you have one of these pumps, how about you calling Terry and ask him if PT ordered the pumps with relief valves. He has already told me yes, but please go ahead and ask for yourself, and maybe we will know the truth. I can see where they install on the pump, but it is an option.

Stray, do you have this same pump?

 

[SnowRidge]

SnowRidge.

Since you have one of these pumps, how about you calling Terry and ask him if PT ordered the pumps with relief valves. He has already told me yes, but please go ahead and ask for yourself, and maybe we will know the truth. I can see where they install on the pump, but it is an option.

Stray, do you have this same pump?

Did you specifically ask, and did he specifically tell you they have high pressure relief valves, as opposed to the charge pump relief valve, which is standard?

Where do you see them installing on the pump? The only place for additional relief valves is in the implement circuit. The implement circuit is an extension of the charge pump, and it is not used in the PTs. Those are roughly 800 PSI reliefs, BTW, not suitable for the tram circuit.

 

[J_J]

Did you specifically ask, and did he specifically tell you they have high pressure relief valves, as opposed to the charge pump relief valve, which is standard?

Where do you see them installing on the pump? The only place for additional relief valves is in the implement circuit. The implement circuit is an extension of the charge pump, and it is not used in the PTs. Those are roughly 800 PSI reliefs, BTW, not suitable for the tram circuit.

http://www.sauer-danfoss.com/stellent/groups/publications/documents/product_literature/bln-10006.pdf

Page 26 of 32 From what I can figured out, that is where they go, if installed. Maybe you can check your pump to see if anything is under that cap. If you see a nut or screw adjust, then I suspect they are there. If blank, then they are not installed.

 

[SnowRidge]

http://www.sauer-danfoss.com/stellent/groups/publications/documents/product_literature/bln-10006.pdf

Page 26 of 32 From what I can figured out, that is where they go, if installed. Maybe you can check your pump to see if anything is under that cap. If you see a nut or screw adjust, then I suspect they are there. If blank, then they are not installed.

I think those ports are just capped. If I get a chance, I will pull whatever is there tomorrow.

I think I figured out why the Service Manual doesn't mention those ports or the high pressure reliefs. It is dated 1990. The Technical Information document is dated 2000. The Service Manual is completely out of date. It doesn't mention the SAE "A" Auxiliary Flange either. I believe that is used on the newer PT-425s that have all the pumps on one end. It is not present on my pump.

 

[stray]

Guys i sent this note to Power-Trac. I sent it yesterday and didn't get a reply today so i sent again today. As soon as and if i get an answer i will share it with you all.

I have been doing some engineering on my 2003 422 22 horse power robin engine Power trac. Several of us are involved in the aspect of being able to change the gearing to a slower more powerful speed by running all 4 wheel motors in a parallel mode rather than the right left pair of 2 motor serious. I have designed and install a quick disconnect system that allows me to switch back and forth from the 2 serious to the 4 motor parallel mode. I am sure you are aware of the Tractorbynet site for the Power-tracs. We would appreciate it very much if you can set us straight on relief valves.

Questions
First: does my wheel motors on the 2003 422 have relief valves in them. If so what were they set on from your factory?

Second: Does the charge system have relief valves or valve in it? What was it set on?

Third: does the tram system have relief valves in it and if it does what was it set on.

You have a lot of Lowell PT owners on the tractor-by-net site and this seems to be a hot topic. Any help you can give us on this will be shared and appreciated by several Pt Owners. Sevel people with the 425痴 are interested in this too.

Here is a link to the tread on this. Please help us with as much detail info on the relief valve as you can.

Craig A Cooter


http://www.tractorbynet.com/forums/power-trac/137695-more-torque-my-power-trac.html

 

[J_J]

Do you guys not have parts manuals for VSP pumps. If you do, it will indicate whether you have relief valves.