Two speed modification for PT 422/425

[stray]

Solenoid valves would position themselves thus when the PT would be in the regular mode as it comes from the factory.

 

[stray]

One more. The way PT is set up now. simpler and less hoses. Keeps a person from wanting to change?????

 

[stray]

This is everything needed to swap over to the parallel mode and test its efficiency. Most every thing I do is on level or slightly sloped ground so I don't really need to pursue this but I thought it would be interesting. I think we have lost interest in this anyway. Maybe I could ship it to someone more willing to try it.

 

[BobRip]

Stray, don't give up now. Everyone is dying to see if this works. It actually looks simplier when you show the parts. One of my biggest complaints has been the wheel torque. Keep going!!

Bob Rip

 

[KentT]

</font><font color="blue" class="small">( Stray, don't give up now. Everyone is dying to see if this works. It actually looks simplier when you show the parts. One of my biggest complaints has been the wheel torque. Keep going!!

Bob Rip )</font>

I agree with Bob -- we want to see how well this will work!

 

[BobRip]

Stray, I have to make one more comment. When I took the class on the PT422, I was told that the wheel motor circuit is very clean (everybody knows this). They also told me that if you ever open that circuit then you better flush it with a 3 micron filter kit that they sell. This kit was $700 at that time (2000). In addition you have freshly made hoses and machined parts. There is probably some trash in both of these. You should probably flush this trash out before you even connect them to the PT and then flush with the 3 micron filter. This is not my area of expertise, but it is what PT has told me and others who know hydraulics. Hopefully others will chime in here with more expert advise.

Bob Rip

 

[RegL]

I'm not very knowledgeable about this, but why would the wheel motor circuit be that much cleaner. There's only one oil supply being used by all circuits. I don't see why you would need to flush through anything finer than what's used on the PT. I think for 700 bucks I would take my chances.

 

[stray]

I will blow it clean but I am sure that I won't be filtering it at 3 micron. One thing I do swear buy is don't use Teflon tap on the fittings. The tape can shred off when screwing fittings in and leave small particles that can cause malfunctions. Using teflon tap on hydraulics, you might get by with it but your just asking for trouble.

 

[BobRip]

I was just trying to give you a little extra information. Now some better news. If I understand the wheel motor circuit flow, when the pump is in neutral (machine pedals centered and wheel motors not moving) it looks to me like all of the flow goes through the cooler and back to the oil tank. So if you let the engine run for a while then the dirt will be flushed back to the tank and back through the filter before getting into the traveling pump or even the wheel motors. If before you connect your hoses to the motors, you let them drain back into the tank through the fill cap and flush for a while, you will go a long way to flush the particles out of the system before it does any damage. Of course you will need to push on the pedal and switch between modes during the flushing. At least this ensures that you have a 10 micron filter before going through pump and wheel motors. I am not sure exactly sure how the pumps works, so someone who does know, please comment. Question - Will not having back pressure with the hoses open cause any damage?

Good luck, and thanks for doing this project.

Bob Rip

 

[Ducati]

I believe this kind of modification is a standard in the Finnish built Avant 220 tractor. It can be switched on/off depending on the terrain.