Help, No forward motion!

[coolconnection]

As I understand it, and this could be incorrect, the oil goes from the tank, through the existing filter, to the charge pump, to the variable volume pump as makeup oil. Any oil that slips past the VVP goes to the oil cooler, then back to the tank.

The VVP itself is reversible, depending on the angle of the swash plate. Neutral when pedals are centered. Press the forward pedal and fluid flows out to the wheel motors. Let up and it stops. Push down on the reverse pedal and the fluid flows the other way.

I don't see how you could filter the wheel motor circuits under operation, as it would backflush the filter each time you reversed direction.

You could filter them with a temporary filter placed in-line right at the input or output of the VVP and running the machine up on blocks in one direction only.

At least, that's the way I understand it.

Yeah, that is what I was thinking and that don't sound to bad. Now to get the parts. I can put it up on blocks and run it for awhile in one direction. I'm not in a big hury to get it running but I do want to do it so no more problems pop up.The company I found that would flush it wants over $400 just off the bat and it will go up.

 

[woodlandfarms]

On the 1850 series I have there is a high pressure filter on the lift tilt dump circuit. I think it is pretty porous but it is something. I believe it was discontinued on the latest model.

 

[ponytug]

They do make filters that are designed for two way oil flow. Not cheap, but they do exist. Think sets of check valves that let the oil flow from a to b or b to a, but always the same way across the filter.

All the best, Peter

As I understand it, and this could be incorrect, the oil goes from the tank, through the existing filter, to the charge pump, to the variable volume pump as makeup oil. Any oil that slips past the VVP goes to the oil cooler, then back to the tank.

The VVP itself is reversible, depending on the angle of the swash plate. Neutral when pedals are centered. Press the forward pedal and fluid flows out to the wheel motors. Let up and it stops. Push down on the reverse pedal and the fluid flows the other way.

I don't see how you could filter the wheel motor circuits under operation, as it would backflush the filter each time you reversed direction.

You could filter them with a temporary filter placed in-line right at the input or output of the VVP and running the machine up on blocks in one direction only.

At least, that's the way I understand it.

 

[coolconnection]

Got of the phone with Terry and my pump is on its way back. I asked about cleaning the lines. He said don't worry about it the pump was very clean inside. He said when I hook everything back up the filter will take care of anything left in the lines. The cause was I broke both bolt heads off that hold the swash plate on. He said all the parts were still in there. I asked what could cause that to happen. Just a fluke, he couldn't tell me. In reality it is just my crappy luck I guess. Either way I am going to do my best to flush anything out of there I can because I am replaceing all the oil with new fresh liquid gold. Thanks for all your help and suggestions. This still is the best forum on the internet. Helpful and knowledgable people not to mention nice as well.

 

[Incline]

So, I've been following this thread hoping to gain some clarity but I have to show off my ignorance and ask some questions about terminology. I've read no fewer than 5 "pumps" called out in this thread: Main; Charge; Variable Volume; Tram; VD.

My manual (which has pictures of completely different mechanics and pumps than I have on my machine) provides schematics for just 2 pumps: System; and PTO/Steering. They do show pictures and/or make reference to a tram pump and variable volume pump but no guidance as to what they do - and as I mentioned, the pictures look nothing like what I have on my machine (which is unfortunate because I still can't tell which valve to turn should I ever need to tow it)

More to the point of this thread - I'm trying to get my head around how/why the wheel motors would be in a "closed system". I attached 2 schematics of the system pump (is this what's been referred to as the Main or Charge pump?) Seems like the oil flows through the filter and into the system pump, then on to the wheel motors. If that were it, I could see where the system is closed but the treadle valve schematic, which presumably modulates the flow of oil to the wheel motors shows oil flowing through the system pump and back to the oil tank.

I'm sure I'm missing something but I do find it odd that some members report increased power to the wheels when they've changed the hydraulic fluid to synthetic oil. If it's a closed system, that new synthetic oil would not replace the oil the machine came with unless the wheel motor system were bled.

Mostly just looking for some guidance on the terms used so I can try to follow along.

Thanks



View attachment System Pump pt425.pdf

View attachment Treadle valve.pdf

 

[MossRoad]

I'll give it a shot.

There are three pumps.

- 1 pump is for directional travel. It is called a variable displacement pump. Variable volume pump. Tram pump.

- 1 pump is for the main PTO. It powers implements like the mower decks, brush cutter, sump grinder, broom, etc...

- 1 pump is for steering, Front End Loader arms, and the quick attach system. The quick attach system is disconnected from the QA cylinder and attached to other cylinders on implements like the power angle cylinder on the snow plow. This is called the AUX PTO and is operated by the lever by the operator's right knee. The flow for this pump goes from the pump, to the steering valve, out a power-beyond port, and to the 3 valve bank for the FEL/AUX PTO lever (sometimes called the quick attach lever).

 

[marrt]

I'll give it a shot.

There are three pumps.

- 1 pump is for directional travel. It is called a variable displacement pump. Variable volume pump. Tram pump.

- 1 pump is for the main PTO. It powers implements like the mower decks, brush cutter, sump grinder, broom, etc...

- 1 pump is for steering, Front End Loader arms, and the quick attach system. The quick attach system is disconnected from the QA cylinder and attached to other cylinders on implements like the power angle cylinder on the snow plow. This is called the AUX PTO and is operated by the lever by the operator's right knee. The flow for this pump goes from the pump, to the steering valve, out a power-beyond port, and to the 3 valve bank for the FEL/AUX PTO lever (sometimes called the quick attach lever).

To add one thing...the charge pump is INSIDE the VD (Variable Displacement) pump. In the first diagram, the VD pump is item 1, "System Pump." On your tractor, charge pressure is also used, through the treadle, to regulate the angle of the swash plate, and therefore, the direction of the tractor. This isn't unusual.

 

[marrt]

I talked to Terry and he said your not even close to be in panic mode. The wheel motors do eventually drain back into the holding take he said.

What is the definition of "eventually" in this context? That's what I was talking about at the end of my last post...how much "leakage" is normal in these circuits. Further, the White motors in the 425 do not have a dedicated case drain. So, from a practical perspective, how could this circuit ever be filtered? Regarding your oil and condition of the pump, the particles that cause the most damage are too small to see. If your oil is dark, it's more likely from thermal breakdown IMHO. Definitely replace it though. All hydraulic machines require the hydraulic oil to be changed periodically. I replaced it in my Kubota's at 50 hours. My Takeuchi track loader also uses motor oil for hydraulic oil and the replacement cycle is every 1000 hours. For the Takeuchi mini-x, it's every 2000 hours depending on attachment use. Just to give you an idea of the range. Keep in mind, a commercial machine will reach these cycles every 1 or 2 years.

I've been curious for a while as to why these pumps from Power Trac fail so often. I've had one fail at <400 hours and another one on a different machine at <700 hours. This is crazy. A few people get a lot of hours out of them but that seems fairly rare, just going by this forum. For a lot of equipment used commercially, a failure rate this high would mean replacing the pump once or twice PER YEAR. To solve my curiosity, I hired a hydraulic consultant who's written several books on hydraulic maintenance to help me understand what is going on. What I've written is based on his advice.

The diagram for the filter I built is below. It uses a 3 micron filter (special order) and a filter case like this one (SAE 12 3 GPM High Pressure Filter | Filters | Hydraulic Filters | Hydraulics | www.surpluscenter.com). I added some gauges and a flow meter as well but they aren't needed for the basic setup in personal use. I probably wouldn't try to plumb this in permanently because there's not really enough room in the tub and it's hard to find an affordable high pressure filter that will take the pressure full time. I'm using a high pressure filter that's rated for about 3K PSI but I filter the tractor on blocks with the wheels off. Some pumps will generate over 5K intermittently under load. With the wheels off the ground, the circuit generated about 700 PSI if I remember correctly. This is plumbed IN LINE at the wheel motor....meaning you remove any line that's convenient and connect it to any line on the filter. Connect the remaining line from the filter back to the motor. When connected, you can reverse direction of the tram to reverse flow in the circuit (this is even advisable). I'm going to filter the circuit on my 1845 this week and I'll try to get a picture.

 

[marrt]

I guess I should add...coolconnection, I'm not trying to scare you with any of my comments. I'm just trying to give you the full picture so you can decide how much time and money (and hassle) you want to invest for more peace of mind. Something sounds fishy about the two bolts that broke, along with your previous problems. You could end up doing a lot of work on the filter or whatever only to find out later there's another problem. If it were me, I'd probably do the least possible now or I'd completely rebuild the thing. So there's nothing wrong with throwing the old pump back in, replacing the oil, and seeing what happens. If it breaks again, then you'll know for sure you need to do something more drastic.

 

[coolconnection]

I've heard I'm not the only one with these problems. I asked Terry can I get a pump like what on the new ones. He said no because they don't use that pump in the new ones anymore. They have a totally different setup and it's cast iron now. Still thinking about running a temporary filter in the lines. I like your idea marrt.