644 more pics

[thebuildist]

Yes, I was confused. I was referring to the attachment relief, and I was in the ballpark as far as that goes.

For the main travel relief, I wasn't even in the same neighborhood as the ballpark! So the 400 series main travel relief is right around 2000, and the 600 series are closer to 2300. That is a difference, not a dramatic one, not nearly as dramatic as 475 vs. 1200.

To be honest, I don't really see the point of the 400 series' relatively lower relief. The piping and components are all the same strength/integrity as the loaders. Why not have it dialled up higher?

But good catch, thanks for shedding light on the situation.

A side issue, but on my 4020, where I machined a full-sized power beyond into the attachment side of the TCV, when I first hooked up that new PB output to a guage, I was shocked. I was routing all the flow coming from the travel motor/circuit into the new PB port, and I expected full flow at travel circuit pressure. (about 9 gpm, about 2000 psi) But because the power beyond port is coming from the attachment circuit, the available pressure is only eqal to the attachment relief, in my case about 475 psi. So I had full flow available, but very low pressure running to my new loader cylinders. That one almost stumped me.

Bob

[Spike188]

@thebuildist Did you end up boosting the 4020 attachment relief pressure up from 475 psi?

[Eugen]

@thebuildist I'm not sure I actually understand that. The 644 also has a hydraulic cylinder under the tractor, for attachments, right? I took apart that attachment cylinder. I could be wrong but that cylinder doesn't seem to be constructed for a 1000 psi pressure.

[MattA]

@thebuildist I'm not sure I actually understand that. The 644 also has a hydraulic cylinder under the tractor, for attachments, right? I took apart that attachment cylinder. I could be wrong but that cylinder doesn't seem to be constructed for a 1000 psi pressure.

Does your 644 have a different relief pressure for the mid lift cylinder? I think the mid lift cylinder wasn't added to later loaders (but I could be wrong).

I also thought Bob was talking about the 2000psi vs 2300psi drive pressure relief. At some point the loaders got a heavier differential and somewhere around the year 2000 before my tractor was built, the backhoe transaxle complete with revised gearing and the heavier differential went into the newer tractors.

[thebuildist]

@thebuildist I'm not sure I actually understand that. The 644 also has a hydraulic cylinder under the tractor, for attachments, right? I took apart that attachment cylinder. I could be wrong but that cylinder doesn't seem to be constructed for a 1000 psi pressure.

Well, understand that I've never actually seen a 644 in person. So I don't know if it has a mid-lift cylinder or if it does what kind. I can only go by the schematics I've seen of their hydraulic system, and that chart that says that the attachment circuit pressure relief is set for 1,050 PSI. And I can see based on the size of the lift cylinders that they are oversized to get adequate lifting force from relatively low pressure.

I had just assumed that that cylinder will in fact hold up under right around a thousand psi but not more.

Bob

[thebuildist]

@thebuildist Did you end up boosting the 4020 attachment relief pressure up from 475 psi?

Yes, I ended up blocking off the attachment relief altogether. Which gave me around 2,000 or 2,300 psi out of the power beyond port. Which is fine for what my loader cylinders need.

Then I had to install new pressure relief for the attachment circuits at a point after the fluid has left the TCV. And this stupid part is that I had to have one relief for the up lines and another separate relief for the down lines.

It was too expensive and too much of a mess to buy two different pressure relief valves and pipe them in. And I couldn't find anybody that sold a relief valve with dual/separated ports, so I built my own! A little bit to my own surprise, it works perfectly.

Bob

[Harry]

Both of my 600 series GT’s had the center lift cylinders. The 644 lbh is a 1974 and with a hoe on the back, the center lift cylinder would have never been used. I’ve seen people mowing their lawns with a loader on their GT, but never with a hoe hanging off the back. I removed the cylinder and kept the circuit for a possible thumb down the road. On the 646 which is a 1977 it also had a center lift cylinder which I removed. The circuit is used for lifting the 3 point on the rear. I’m not sure what the attachment reliefs are set for on the 600’s because I’ve never checked them. I could because I have gauges installed on them to check pressure, but I’ve never heard them squeal. That’s my 600 series ramble for this morning. Harry

[Harry]

Trying to capitalize on the great fall weather. Garden put to bed for winter. Moved many buckets full of clay and rocks and dirt and sod. Not quite where I want it to be but looking good. Also tilled to strips beside garden to be furrowed out tomorrow to make two drainage trenches to the back where its low. Rain coming in on Friday for a few days so trying to get as much done as I can. Harry

[thebuildist]

'Looks like fun, @Harry ! You're doing it right!

Bob

[JSinMO]

The 644 is looking good @Harry !
It sure make dirt work easier!