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.

 

[rox]

Ducati,
I want to respect the forums, like this is the power trac forum, but I also think it is appropriate to mention in the forums other equipment that is similar to the equipment of the forum topic. This little Avant tractor/skid steer is really really similar to a Power Trac. Since I'm in France and the Avant is made in Finland I checked them out. I started a new thread in the other Brands - here

http://www.tractorbynet.com/forums/showflat.php/Cat/0/Board/other/Number/781411

I really thought hard about buying a Power Trac and shipping it by boat to France, but I think this Avant is a more practical solution. The Power Trac and the Avant are similar.

So Power Trac guys and gals I won't mess up your forum, back to 'yall

 

[BobRip]

</font><font color="blue" class="small">( 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. )</font>

<font color="green"> </font> That is the first I have heard that teflon tape is bad for hydraulics. I used it when I replaced the stump grinder motor. It's probably a little late to change now. What do you use instead?

Bob Rip

 

[stray]

Like I said you might get by with it. What can happen is the tape shreds off the ends it was wrapped on and gets caught in small hydraulic ports. If you do use Teflon tape use no more than 2 wraps and leave the last two threads unwrapped (the threads on the very end). I am as guilty as the next person of using Teflon tape and I have taken apart valves and found that small slivers of the tape were the culprit. Removed that and the valve would be ok.

 

[BobRip]

Is there another alternative? How about the teflon grease that plumbers use? Is nothing on the threads the best option?

Bob Rip

 

[stray]

</font><font color="blue" class="small">( Is there another alternative? How about the teflon grease that plumbers use? Is nothing on the threads the best option?

Bob Rip )</font>
Yes the Teflon grease would be better. Its not the Teflon that is such a risk but the fact that it slivers off and ends up in the system in a solid form. What ever you put on treads serves as much as a lubricant (so the treads can be tightened) as it does a sealer.

 

[toolz_not_toyz]

</font><font color="blue" class="small">( Is there another alternative? How about the teflon grease that plumbers use? Is nothing on the threads the best option?
)</font>

Good luck getting a tight seal by using nothing on the threads, especially for any fitting that is under pressure. The answer would be no.

I have used teflon tape on water pipes for about twenty years and have seen evidence of shredded bits of teflon when clearing a new line. I think the problem is caused when you overlap the tape across the opening of a fitting. I can't see how the tape would cause problem if you don't do that. Obviously, clean off the fitting immediately after disassembly. In recent years I have started to use paste instead in some cases.

The local propane guys around here have advised me to start using BOTH tape and paste on propane fittings (I think that's weird, but whatever).

I think if there's a possibility to get teflon tape in your circuit then it is also possible to get residue from the paste in there as well.

 

[stray]

Guys I don’t know what else to tell you. Here is what I use professionally on Hydraulics at work as well as at home. That said, in a pinch I have used Teflon tape but I was asking for trouble, it tends to squirt out the end of the treads when tightened. I definitely agree, you do need to use some kind of sealant.
Loctite 567 item no. 56747
PST PIPE SEALANT WITH PTFE
High temperature For Stainless Steel and Other Metal Fittings
The two tubes pictured are the same thing.

 

[toolz_not_toyz]

I didn't know you could use Loctite for this application.

 

[Phils]

Just to affirm a point: my propane people use (and recommend) BOTH teflon tape and teflon paste for propane pipe connections. I first learned this maybe 20 years ago when we were installing all the underground piping to the house and outbuildings. I've followed this rule ever since even for water piping. But not for hydraulics, where I use paste only and try to be VERY careful, leaving at least 2 threads bare at the end. No problems so far with any connections.

Phil

 

[stray]

</font><font color="blueclass=small">( I didn't know you could use Loctite for this application.

)</font>

Just so there is no misunderstanding this is a Loctite BRAND tread sealant. Not the Loctite brand loctite that locks threads in place. At one time this confused me too. /forums/images/graemlins/confused.gif