Tow/Bypass Valve Limitations PT-425 & Perhaps Others

[SnowRidge]

A better word or words would be AUX HYD . You can use it for whatever, a cylinder, hydraulic motor, The aux hydraulic has a small pump, somewhere around of 1.5 to 3 gpm. At least mine does, and this same pump also controls the steering, lift circuits, and aux hyd.

My PT manuals do not show the aux circuit at all, and the illustrated parts diagram does not break down the PTO/Lift/Steering pump at all, but treats it as a single part. I have no idea what the flow rate on mine is. The manuals can be very frustrating.

 

[woodlandfarms]

Sedgewood had links to these files. In a way for me it give a clearer picture of how this pump works.

there are a few things I still don't get, but I want to formulate the questions clearly.

Here is the link to the PDF's as they are too big for TBN

ttp://www.sauer-danfoss.com/domdb/SASproducts.nsf/2dd81f77829d09d086256591004f57d7/5d44424d42f146f9862565d100577a08?OpenDocument

 

[Rivco]

My PT manuals do not show the aux circuit at all, and the illustrated parts diagram does not break down the PTO/Lift/Steering pump at all, but treats it as a single part. I have no idea what the flow rate on mine is. The manuals can be very frustrating.

Isn't the AUX. HYD. /AUX. PTO circuit on the 422 & 425 operated by the lever by your right leg, and isn't that lever attached to the 3-spool SAUER/DANFOSS valve ?. So the flow rate would be what ever the spool valve is set at (pressure & flow rate ). If you go to the SAUER/DANFOSS site and read the spec's for the 1637 3-spool valve it should give you the factory settings.

 

[SpringHollow]

I guess my ignorance is showing more than normal. I do not understand how one can drain the lines/pumps/motors if inlets/outlets are all connected below the fluid level in the tank. Well, in my system I can understand because I have not fixed all the leaks so if the system leaks fluid out, it can leak air in. I do understand how it can overheat when one is recirculating the same fluid.

Ken

 

[SnowRidge]

Isn't the AUX. HYD. /AUX. PTO circuit on the 422 & 425 operated by the lever by your right leg, and isn't that lever attached to the 3-spool SAUER/DANFOSS valve ?. So the flow rate would be what ever the spool valve is set at (pressure & flow rate ). If you go to the SAUER/DANFOSS site and read the spec's for the 1637 3-spool valve it should give you the factory settings.

That doesn't tell me what the pump is rated at.

Those spool valve specs are what it can handle. The valves don't regulate pressure or flow. They just direct it.

 

[SnowRidge]

I guess my ignorance is showing more than normal. I do not understand how one can drain the lines/pumps/motors if inlets/outlets are all connected below the fluid level in the tank. Well, in my system I can understand because I have not fixed all the leaks so if the system leaks fluid out, it can leak air in. I do understand how it can overheat when one is recirculating the same fluid.

Ken

Good point, Ken. Maybe excessive towing causes the wheel motors, which are acting as pumps, to pull a partial vacuum in the lines while forcing leak-by oil out the tram pump's return line.

The intake line is blocked by the non turning charge pump.

 

[SnowRidge]

Sedgewood had links to these files. In a way for me it give a clearer picture of how this pump works.

there are a few things I still don't get, but I want to formulate the questions clearly.

Here is the link to the PDF's as they are too big for TBN

ttp://www.sauer-danfoss.com/domdb/SASproducts.nsf/2dd81f77829d09d086256591004f57d7/5d44424d42f146f9862565d100577a08?OpenDocument

That isn't for the same pump series that is used in my PT-425. I don't know about the other models.

 

[Rivco]

That doesn't tell me what the pump is rated at.

Those spool valve specs are what it can handle. The valves don't regulate pressure or flow. They just direct it.

Thanks for correcting me Maybe you can get that infomation from terry at PT.

 

[BobRip]

Yes that is the one. I had to cut (shorten) the dip stick but otherwise was able to use the cap as is.

Did the cap just screw on to the existing bottom?

 

[BobRip]

Yes that is the one. I had to cut (shorten) the dip stick but otherwise was able to use the cap as is.

I got my cap today and it works fine. Only about 1/4 inch clearance between the bottom of the seat and the top of the cap though. Did you adjust the seat any?