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Cat track loader purchase

DMiller

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RTD on the 963 I use uses a magnetic switch for point of level on the bucket, would wonder if may have a lead broken in that circuit harness, is encased in a tube along top of curl cylinder. The unit I use has been unavailable for quite some time and has been essentially deleted.
 

ippielb

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As a first step I suggest to test the pilot pressure. It is supplied by a pressure-reducing valve from the main system.
Spec is 348 +/- 7psi at pressure tap 1.

View attachment 243017

got a mechanic out, 445-460psi at the port.

guess I need to adjust shims in the relief. He has access to the cat tools. And he just sent me a picture here.

1696C048-3C75-4E0B-883F-39065F1CD00F.jpeg

Shows what shim does what change of pressure.
 

Nige

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If he has access to SIS (from photo above) then did he do the 2nd test for pilot pressure.? It's important to do that one before starting to mess around with shims. A measured value of 100psi above spec suggests to me that something isn't quite right somewhere and adding/removing shims is not necessarily going to fix it.

I'll send you the full document.
 
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ippielb

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Okay, so what i understand the pilot pump outputs a pressure to the feed line on the pressure reducing valve. And that pressure from the pump should be 348psi + or - 7 psi. And my pilot pump is showing 448psi on the gauge tonight when i checked. So before any changes are to be made on the pilot pressure reducing valve with the shims. I need to get my pilot pressure down to 348, and then follow the steps in the PDF you gave me on page 10.

I do not see a pressure relief valve on my pilot pump at all.
3E02FB9D-AACB-40A9-9D3D-FF9B981DB94E.jpeg A06D5C7F-00A8-4D2B-A03C-819775DC92BB.jpeg
 

Nige

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All the pump does is provide a flow of oil. The valve below is what controls the adjustment of the 348+/-7psi pressure. The combination of the spring #1 and the shims #2 & #5 in other words. I think that you are so far off specification with a measured pressure of 448psi that it is very possible that something is wrong inside the valve that adding/removing shims will not fix.

My first suggestion would be to remove the two Adapters #3 from each end of the valve, then remove the spool and the spring. Take a look inside the bore for scoring, etc. Check the spool for any type of damage or wear. Inspect the spring for damage and measure the free length. It should be 50.5mm. With 27.5 +/- 2.0kg of force applied to it the length should be 44.1mm. Note the quantity of thick (#2 - 0.9mm) and thin (#5 - 0.25mm) shims installed in the valve. There should also be a single spacer (#6 - 2.7mm thick) right next to the end of the spring. The quantities of each listed in the Parts Manual are shown below. Those numbers would be the starting point for making any adjustments.

upload_2021-10-8_11-23-44.png

upload_2021-10-8_11-4-44.png
 

Nige

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BTW the illustration in Post #483 that the mechanic sent to you is not the correct one for 3RZ00297. That illustration is for a 119-5988 Valve that applies to machines 3RZ00626-Up. The illustration of the valve I posted above is a 1U-2226 fitted to all machines from 3RZ1 to 3RZ625.
 

ippielb

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All the pump does is provide a flow of oil. The valve below is what controls the adjustment of the 348+/-7psi pressure. The combination of the spring #1 and the shims #2 & #5 in other words. I think that you are so far off specification with a measured pressure of 448psi that it is very possible that something is wrong inside the valve that adding/removing shims will not fix.

My first suggestion would be to remove the two Adapters #3 from each end of the valve, then remove the spool and the spring. Take a look inside the bore for scoring, etc. Check the spool for any type of damage or wear. Inspect the spring for damage and measure the free length. It should be 50.5mm. With 27.5 +/- 2.0kg of force applied to it the length should be 44.1mm. Note the quantity of thick (#2 - 0.9mm) and thin (#5 - 0.25mm) shims installed in the valve. There should also be a single spacer (#6 - 2.7mm thick) right next to the end of the spring. The quantities of each listed in the Parts Manual are shown below. Those numbers would be the starting point for making any adjustments.

yesterday I opened it up to check to see if the spring was broken. And the spring I have is a fairly heavy spring with blue paint on it. I had 3 thick spacers and 4 thin spacers. I did not have one of the #6 against the spring.

for curiosity sake I took two thick spacers out and reassembled to see if any changes would happen. And no change to the pressure it stayed at 448 with two thick spacers removed.

Adding spacers would increase the pressure at the test port correct? As it is creating more back pressure from a stronger spring rate basically.

I will dissemble the valve and inspect it tonight when I get home from work. We don’t get much daylight anymore the sun is down by 6:30 and I don’t get gone till 5.
 

Nige

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The blue stripe on the spring appears to be correct.
upload_2021-10-8_15-9-26.png
If you have only used the same pressure gauge for all the measurements taken so far I would suggest that you try using a different gauge, just to see if it makes any difference.

I think it's also worth carrying out the tests in Steps 3 & 4 on Page 10 of the document I sent to you. To do this will involve some additional fittings because you have to tee into "Line A".

3. Raise the bucket in the air. Ensure that the lift pilot valve and the tilt pilot valve is in the HOLD position. Shut off the engine.
4. Lower the bucket for a short distance and make sure that the pressure reducing valve does not contain the higher pilot pressure that may be trapped. Precisely when the lever is returned to the neutral position, check the pilot system pressure at the outlet port (A) of 119-5988 Selector and Pressure Control Valve (3) . The pressure should be 1350 ± 100 kPa (195 ± 15 psi).


To check the Part Number of the valve please take a look at the body and see if there is either a P/N stamped on it or a data plate somewhere. The fact that you didn't find the 2.7mm-thick spacer is an indication that you could have the later P/N of valve despite the fact your machine falls into the "earlier valve" category.

I'd like some of the track loader experts to chime in because looking at the hydraulic schematic it appears to me that the pressure reducing valve can get back-fed from the lift/tilt pilot valves and I'm not sure what effect that could have on its operation. Hydraulic schematic attached.
 

Welder Dave

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It seems odd the pressure gauge reads exactly 100 PSI too high. I think Nige is correct to try a different gauge.
 

ippielb

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DE8FF82E-5E77-4E61-A1C9-9D72F9AF6ADE.jpeg
the only thing that stood out to me was this small metal shaving on the valve side. There was no scoring on he valve or in the body. Just some mild scuffing none that you can catch a nail on.

that metal shaving was very stuck on there as well it wasn’t a loose shaving. Brake clean didn’t even spray it off.
 
Last edited:

ippielb

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The blue stripe on the spring appears to be correct.
View attachment 246545
If you have only used the same pressure gauge for all the measurements taken so far I would suggest that you try using a different gauge, just to see if it makes any difference.

I think it's also worth carrying out the tests in Steps 3 & 4 on Page 10 of the document I sent to you. To do this will involve some additional fittings because you have to tee into "Line A".

3. Raise the bucket in the air. Ensure that the lift pilot valve and the tilt pilot valve is in the HOLD position. Shut off the engine.
4. Lower the bucket for a short distance and make sure that the pressure reducing valve does not contain the higher pilot pressure that may be trapped. Precisely when the lever is returned to the neutral position, check the pilot system pressure at the outlet port (A) of 119-5988 Selector and Pressure Control Valve (3) . The pressure should be 1350 ± 100 kPa (195 ± 15 psi).


To check the Part Number of the valve please take a look at the body and see if there is either a P/N stamped on it or a data plate somewhere. The fact that you didn't find the 2.7mm-thick spacer is an indication that you could have the later P/N of valve despite the fact your machine falls into the "earlier valve" category.

I'd like some of the track loader experts to chime in because looking at the hydraulic schematic it appears to me that the pressure reducing valve can get back-fed from the lift/tilt pilot valves and I'm not sure what effect that could have on its operation. Hydraulic schematic attached.

I couldn't find either of my calipers to measure the spring, but it is 50mm.

When the mechanic came over he suspected the same thing, we used the glycerin filled gauge first and thought it must have read wrong because like you guys said it is 100 psi over. So he grabbed his digital gauge and it was showing the same thing, he let me borrow the glycerin filled gauge because i dont have any and he's traveling working on machinery.

With adding the T and the test port onto Line A permanently cause any issues? I wonder why CAT never installed one in there in the first place.

To do those steps i will need to get the fittings and a test port. I will call cat tomorrow morning to see if they have them.

In the posts above i have included pictures of the part numbers.

My mechanic says that the reason the valve can get back fed from the lift and tilt pilot valves is incase the machine breaks down with the bucket in the air, the pressure from the weight of the loader arms and bucket will pressurize the pilot so you can safely lower it down.

I was hoping you could explain to me why there is no pressure relief valve on the pump itself, there is no way to alter the pressure going to the test port, the pump will be able to outflow the reducer so even with any spring/shim changes the port will continue to show the output of the pump. Shouldn't the test port be located after the pressure reducing valve?
 

ippielb

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pilot system.jpg
This is a crude drawing of what im trying to say, the line that comes from the pump goes into a T, and the test port is onto the T before the reducing valve, it does directly into the top of the valve. There is no way to reduce the pressure inline without releasing flow/pressure through a relief. Wouldn't it make more sense to have the test port POST reducing valve?
 

Nige

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My mechanic says that the reason the valve can get back fed from the lift and tilt pilot valves is incase the machine breaks down with the bucket in the air, the pressure from the weight of the loader arms and bucket will pressurize the pilot so you can safely lower it down.
A logical explanation. The implement hydraulic "dead engine lower" system works in a similar way on quite a few loaders.
n the posts above i have included pictures of the part numbers.
Can you confirm that the six letters in the area I marked below are NONKNN.? If so that would date the valve body casting to July 2000 - 3 months before your machine was built. That would make your PRV Assembly a 1U-2226, correct for the machine Serial Number and lead us back to the question "where is the 2.7mm-thick shim that should be in there.?"

upload_2021-10-9_10-7-53.png
 

Nige

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I think I have found something.........
There is a pressure relief valve in the pilot pump. It is built into the head of the pump and the excess oil drains back to the implement hydraulic tank via the hose with the aluminium tag on it shown in Post #485.
See attachment. Unfortunately there are very few service parts for the pump and nothing for the relief valve, so if it is damaged then it's a case of a new pump. Since your machine was built a new 204-5130 pilot pump has been introduced. To install that pump will require a different connector on the tank line. See the attached service article.

upload_2021-10-9_10-38-24.png
 

Attachments

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  • SEPD0591 Pilot Pump.pdf
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ippielb

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I think I have found something.........
There is a pressure relief valve in the pilot pump. It is built into the head of the pump and the excess oil drains back to the implement hydraulic tank via the hose with the aluminium tag on it shown in Post #485.
See attachment. Unfortunately there are very few service parts for the pump and nothing for the relief valve, so if it is damaged then it's a case of a new pump. Since your machine was built a new 204-5130 pilot pump has been introduced. To install that pump will require a different connector on the tank line. See the attached service article.

View attachment 246577
That’s what I thought. But on the underside of that there is no adjustment Allen screw and jam nut it is only a smooth headed hex bolt. Is it non adjustable?

also the adapter that would hold the 2.7mm shim doesn’t have much room to fit any more shims in it.

should I remove the pilot pump to get access for the relief and disassemble to see if there is something lodged in it? It’s all back together right now so I can go wash everything under there so I don’t get any contamination.
 

Nige

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That’s what I thought. But on the underside of that there is no adjustment Allen screw and jam nut it is only a smooth headed hex bolt. Is it non adjustable?
It is non-adjustable, but seeing as the O-ring Ref #1 in the illustration below is serviceable then doesn't the cap (arrowed) screw off somehow.? It's on the back side of your photos so impossible to see.
upload_2021-10-9_18-44-39.png
should I remove the pilot pump to get access for the relief and disassemble to see if there is something lodged in it?
Can you get the head of the pump off (4 screws arrowed blue).? If there is anything that can be removed to get access to the relief valve it will be somewhere in the area of the red arrow.

upload_2021-10-9_18-48-57.png
 
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