425 again…movement problems…

[oldnslo]

Modrob
Closed loop hydrostatic drives require a separate charge pump to maintain a minimum “charge” pressure in the “closed loop” circuit.

Closed loop is where oil exits the pump and connects directly to a motor or motors. The outlet of the motor(s) connects back to the other work port on the pump. Since this circuit does NOT connect to the reservoir it requires make up oil to replace leakage losses or the charge circuit.

Some styles of motors used in closed loop applications have an external case drain which allows oil that leaks to drain to tank at low pressure so a high pressure shaft seal is not required. Per Moss Road your machine did not have that feature.

The hydrostatic pump does have a case drain to allow leakage past slippers, pistons, etc. to drain directly to tank. Typically case pressure should be less than 30 PSI to protect the shaft seal.

Typical cause of the slippers being pulled off the pistons is loss of charge pressure causing the slippers to lift off the swash plate.

High case pressures can also cause slipper lift off but that is more common on open loop applications.

Either way I agree most likely not cost effective to rebuild that old of a machine since I would be very surprised if the wheel motors are not damaged.

 

[MossRoad]

It's tempting to rebuild, but let's look at what cost items are involved.

Carcass is there.
FEL is there.
Lift cylinders are there.
Steering valve and cylinders are there.
Don't know condition of engine, but appears to have had a looooong, productive life. Might be worth replacing.

If engine needs replacing, you'd have to cut the screen and transfer the PTO stub from the front of the engine for the VVP.

You'd need variable volume pump, 4 wheel motors, all new hoses. Hydraulic cooler is on the VVP circuit, too, I believe, so who knows if there's any chips in there.
Don't know condition of center joints or any cylinder ends.

People have said a new pump is around $3K. I don't know the cost of wheel motors, but if let's just say $800 for fun.

So you're looking a $6200 just for VVP and 4 wheel motors. Add in a new engine and that's another $3K.

So now up to say $9K... with no time, labor, etc.... the machine cost $8K new in 2001.

That's $14,350 in today's dollars.
A new machine on PT's price list is $15,900.
So value-wise, it's only gone up $1550 in 24 years.
Plus, the new one's have a bit higher lift in inches, and stronger wheel motors. I'm guessing the engine is probably more advanced VS 24 years ago, as well.

So really, a new machine is still a good value compared to the old machine.

Good luck in your decision.

Like I've said in the past, I'd buy another one for myself if ever needed.

 

[2manyrocks]

I'd like to see some pictures of the entire machine.

 

[Modrob]

I'd like to see some pictures of the entire machine.

I’ll display some hopefully later today.

 

[Modrob]

Modrob
Closed loop hydrostatic drives require a separate charge pump to maintain a minimum “charge” pressure in the “closed loop” circuit.

Closed loop is where oil exits the pump and connects directly to a motor or motors. The outlet of the motor(s) connects back to the other work port on the pump. Since this circuit does NOT connect to the reservoir it requires make up oil to replace leakage losses or the charge circuit.
Wow! Many thanks for such detail! I’ll have to study in more detail all of that…just for learning.
And yes, Moss breaks down cost issues very well. My thinking many times (as long as it doesn’t affect others in a negative way) is do just enough to make something work again—might get lucky sometimes and the effort might last for a good period. Or, it might start failing right away, in which case it’s pretty clear it’s “over”. LOL
Some styles of motors used in closed loop applications have an external case drain which allows oil that leaks to drain to tank at low pressure so a high pressure shaft seal is not required. Per Moss Road your machine did not have that feature.

The hydrostatic pump does have a case drain to allow leakage past slippers, pistons, etc. to drain directly to tank. Typically case pressure should be less than 30 PSI to protect the shaft seal.

Typical cause of the slippers being pulled off the pistons is loss of charge pressure causing the slippers to lift off the swash plate.

High case pressures can also cause slipper lift off but that is more common on open loop applications.

Either way I agree most likely not cost effective to rebuild that old of a machine since I would be very surprised if the wheel motors are not damaged.

 

[Modrob]

It's tempting to rebuild, but let's look at what cost items are involved.

Carcass is there.
FEL is there.
Lift cylinders are there.
Steering valve and cylinders are there.
Don't know condition of engine, but appears to have had a looooong, productive life. Might be worth replacing.

If engine needs replacing, you'd have to cut the screen and transfer the PTO stub from the front of the engine for the VVP.

You'd need variable volume pump, 4 wheel motors, all new hoses. Hydraulic cooler is on the VVP circuit, too, I believe, so who knows if there's any chips in there.
Don't know condition of center joints or any cylinder ends.

People have said a new pump is around $3K. I don't know the cost of wheel motors, but if let's just say $800 for fun.

So you're looking a $6200 just for VVP and 4 wheel motors. Add in a new engine and that's another $3K.

So now up to say $9K... with no time, labor, etc.... the machine cost $8K new in 2001.

That's $14,350 in today's dollars.
A new machine on PT's price list is $15,900.
So value-wise, it's only gone up $1550 in 24 years.
Plus, the new one's have a bit higher lift in inches, and stronger wheel motors. I'm guessing the engine is probably more advanced VS 24 years ago, as well.

So really, a new machine is still a good value compared to the old machine.

Good luck in your decision.

Like I've said in the past, I'd buy another one for myself if ever needed.

Thanks again my good fellow. That kinda hits right-between-the-eyes. Wife is smarter—she already decided we’re going to get a new one. And seeing the new unit on display at HQ, it’s been updated in some areas…one area is much more room for knees and feet area. More comfortable now.
Looking forward to getting it soon. (Was going to place the order this week, but wife got called to work out-of-town this coming week, so hopefully week after that.

 

[MossRoad]

 

[muncybob311]

Good move! And like MR, I would not hesitate in buying another PT if needed. I can't imagine being w/o it.

 

[Modrob]

I guess I should close out this epic.
The old 2001 unit was retired, and on April 10 we took delivery of a new PT425 at the front doors of Power Trac. And Terry was with us the whole way. (What a great guy, and so knowledgeable!)
For now the old girl sits forlornly, a shadow of her former self. (I can relate to that more every day) I probably need to cover it up pretty tight in the meantime…until the wife decides what to do. Again, she’s had an attachment to it all those years and it’s hard to let go…me, I think if I could find those bad pump components and put it back together, it might still have a little more life. MIGHT. But I could only piddle with a project like that if I can ever get so many other things off me.
I’ll start a new thread for the new unit and post pics, and what I’ve learned about it so far.
Thanks again for all of your help and guidance.