B1750 dt. Hydraulic Control Block Pressure Relief

[Titan17]

It has been a long while since last post. Previously I posted repair questions regarding my B1750 hyd. pump replacement. Dan (old hokey) was an immense help!!! He set me straight on everything from where to buy pump to setup and relief valve settings.
I sold the tractor 2 years ago to a friend with no problems to speak of. Recently repacked lift / curl cylinders and did a pressure test at work port. It was running low - 1400@2000 rpm. Increased loader relief valve to 1600 as high as it would go.
Checked pressure at block - also 1600psi.
Pulled relief valve from block and would like guidance shimming/adjusting pres. relief before I attempt to do the job. (I returned the loader valve relief to original pressure until main pressure is at normal psi.
New pump was previously installed, screen is clean, fluid flushed.
Pictures are attached.
Hopefully Dan or Wolf man will respond but any first hand experience will be appreciated. T. Y.

 

[North Idaho Wolfman]

It has been a long while since last post. Previously I posted repair questions regarding my B1750 hyd. pump replacement. Dan (old hokey) was an immense help!!! He set me straight on everything from where to buy pump to setup and relief valve settings.
I sold the tractor 2 years ago to a friend with no problems to speak of. Recently repacked lift / curl cylinders and did a pressure test at work port. It was running low - 1400@2000 rpm. Increased loader relief valve to 1600 as high as it would go.
Checked pressure at block - also 1600psi.
Pulled relief valve from block and would like guidance shimming/adjusting pres. relief before I attempt to do the job. (I returned the loader valve relief to original pressure until main pressure is at normal psi.
New pump was previously installed, screen is clean, fluid flushed.
Pictures are attached.
Hopefully Dan or Wolf man will respond but any first hand experience will be appreciated. T. Y.

WHOA... Put that part back in, that's NOT the pressure relief valve , that is the divider / proportional valve, do not change anything with it.
The pressure relief valve is under the tank / overflow fitting (#150).
The pressure adjustment shims are #190 in the picture.

 

[Titan17]

Thank you. This is why I ask questions here. It sure looks like a pressure relief.
Guess this splits flow to power steering at lower pressure/flow.???
I will now bring pump pressure up at the "P" line before loader valve. I will keep it under 2000#. Then adjust at the loader control pressure relief. That's a screw adjustment or should I shim it. I have plenty of various thickness shims.

 

[Titan17]

Is there a formula for shim thickness to raise pressure 300# or trial and error.
I bought an assortment of shims while back. .001 up to .010. I could stack them and check pressure till I reach 1900#. New owner doesn't need or want any higher than that. He's actually satisfied with 4-500 lbs lift at bucket. There's a permanent mounted PTO driven backhoe on tractor so 3ph will never be used.

 

[North Idaho Wolfman]

Is there a formula for shim thickness to raise pressure 300# or trial and error.
I bought an assortment of shims while back. .001 up to .010. I could stack them and check pressure till I reach 1900#. New owner doesn't need or want any higher than that. He's actually satisfied with 4-500 lbs lift at bucket. There's a permanent mounted PTO driven backhoe on tractor so 3ph will never be used.

The pressure is all dependent on the spring tension and that varies, I didn't read any set sizes in relation to pressure, start small and work up.

 

[Titan17]

The pressure is all dependent on the spring tension and that varies, I didn't read any set sizes in relation to pressure, start small and work up.

 

[Titan17]

Thks again for the help. That makes sense. I have a collection of sizes. Going to bring it up to 2000# I'll then set pressure relief at loader valve to below that - if this sounds right.
He doesn't need full lift capacity, just basically light duty lifting.

 

[tractorstuff]

Thank you. This is why I ask questions here. It sure looks like a pressure relief.
Guess this splits flow to power steering at lower pressure/flow.???
I will now bring pump pressure up at the "P" line before loader valve. I will keep it under 2000#. Then adjust at the loader control pressure relief. That's a screw adjustment or should I shim it. I have plenty of various thickness shims.

Whats the name of the coupler/adapted needed to test pressure on a b1750 ? I want to order one.

 

[TheOldHokie]

Whats the name of the coupler/adapted needed to test pressure on a b1750 ? I want to order one.

You need a 3000 PSI pressure gauge and whatever adapter matches it to the pressure supply hose coming to the loader valve.

Dan

 

[TheOldHokie]

Thks again for the help. That makes sense. I have a collection of sizes. Going to bring it up to 2000# I'll then set pressure relief at loader valve to below that - if this sounds right.
He doesn't need full lift capacity, just basically light duty lifting.

I know this post is 6 months old but I was put of commission in January and I want to correct a misconception.

Setting the loader pressure relief lower than the tractor presdure relief reduces your 3pt lift capacity. Loader relief should be >= tractor relief.

Dan

 

[tractorstuff]

You need a 3000 PSI pressure gauge and whatever adapter matches it to the pressure supply hose coming to the loader valve.

Dan

Yes i just seeing if he knew the correct coupler type / size since he has same tractor and loader as me.

 

[TheOldHokie]

Yes i just seeing if he knew the correct coupler type / size since he has same tractor and loader as me.

If you have an LA300 loader you dont need or want a coupler. Disconnect the hose at the P port on the loader valve and sctew your gauge into it. My best guess is you would need a 1/4 female NPT to 1/2" male JIC adapter.

Dan

 

[tractorstuff]

If you have an LA300 loader you dont need or want a coupler. Disconnect the hose at the P port on the loader valve and sctew your gauge into it. My best guess is you would need a 1/4 female NPT to 1/2" male JIC adapter.

Dan View attachment 157053

Dont see "P"

 

[torch]

Recently repacked lift / curl cylinders and did a pressure test at work port. It was running low - 1400@2000 rpm. Increased loader relief valve to 1600 as high as it would go.
Checked pressure at block - also 1600psi.
Pulled relief valve from block and would like guidance shimming/adjusting pres. relief before I attempt to do the job. (I returned the loader valve relief to original pressure until main pressure is at normal psi.

Bear in mind that the loader relief valve will limit what's available at the 3ph because it's first in the chain. If the loader relief is set to, say, 1,500psi and the 3PH relief is set to 1,800 psi then the maximum pressure the system can develop is 1,500psi.

It doesn't work the other way though. If the 3PH relief is set to 1,500psi and the loader is set to 1,800psi then the maximum using the loader is 1,800psi because the 3PH is now cut out of the circuit. The max available to the 3PH is 1,500psi when the loader control is in the neutral position and therefore passing the fluid to the 3PH valve.

 

[TheOldHokie]

Bear in mind that the loader relief valve will limit what's available at the 3ph because it's first in the chain. If the loader relief is set to, say, 1,500psi and the 3PH relief is set to 1,800 psi then the maximum pressure the system can develop is 1,500psi.

It doesn't work the other way though. If the 3PH relief is set to 1,500psi and the loader is set to 1,800psi then the maximum using the loader is 1,800psi because the 3PH is now cut out of the circuit. The max available to the 3PH is 1,500psi when the loader control is in the neutral position and therefore passing the fluid to the 3PH valve.

On that tractor the pump pressure relief that controls 3pt pressure is in the hydraulic outlet block. The loader valve can reduce but not increase that pressure. If the specication for the tractor is 1500 PSI thats the maximum the 3pt AND loader will get.

Dan

 

[TheOldHokie]

Dont see "P"

Look for a port labeled IN. I think its to the right of OUT in your picture.

Dan

 

[TheOldHokie]

Dont see "P"

Here is the outlet block. To measure relief pressure you connect the gauge to port 3 in the picture. You can do that at the block or by disconnecting that hose at the loader valve and connecting the gauge to the hose. Relief pressure should be 1900-193O PSI

Dan

 

[torch]

On that tractor the pump pressure relief that controls 3pt pressure is in the hydraulic outlet block. The loader valve can reduce but not increase that pressure. If the specication for the tractor is 1500 PSI thats the maximum the 3pt AND loader will get.

Dan

Thanks for the clarification.