Your pressure setting sounds normal for a factory setting. If my memory serves me correctly, the factory setting (which should be done at full throttle) is supposed to be 2150 PSI. I now have mine set at 2500 at full throttle. That's a good balance between power and safety, as well as the possibility of damaging your equipment.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
790 lift Capacity
- Thread starter SteveH_CT
- Start date
- Views: 27227
glalonde
Bronze Member
Well,
I've finally done it. I've added only one pack of shims which I find sufficient.
Here are my readings (psi):
idle: no shims added (2000), one pack added (2400)
full throttle: no shims added (2100), one pack added (2500)
I've finally done it. I've added only one pack of shims which I find sufficient.
Here are my readings (psi):
idle: no shims added (2000), one pack added (2400)
full throttle: no shims added (2100), one pack added (2500)
OkieG
Veteran Member
Re: loader wear and tear.
You might check and see what the system pressure is in all the tractor models that use the 70 loader. My 855 uses a 70A loader and runs 2000psi +/-50psi from the factory. The 955 uses the same loader, but has a system pressure of 2500psi. Maybe you can prove to yourself the 70 is designed to handle more pressure.
Re: hydraulic pump wear and tear.
My 855 and the 955 share many parts. The 955's larger hyd. pump was a perfect fit on my 855. After months of happy tractoring, I shimmed the relief valve up form 2500psi to ~2800psi, and blew the pump within minutes. By the way, pumps aren't cheap. Maybe I was unlucky, or maybe you are all lucky. $700+ later, my system is set at 2500psi, which is the recommended pressure for the pump I have installed. If you decide to shim, I strongly recommend investing in a pressure gauge to check where you're at.
My limited personal experience is that pumps don't tolerate much over their rated pressure.
OkieG
You might check and see what the system pressure is in all the tractor models that use the 70 loader. My 855 uses a 70A loader and runs 2000psi +/-50psi from the factory. The 955 uses the same loader, but has a system pressure of 2500psi. Maybe you can prove to yourself the 70 is designed to handle more pressure.
Re: hydraulic pump wear and tear.
My 855 and the 955 share many parts. The 955's larger hyd. pump was a perfect fit on my 855. After months of happy tractoring, I shimmed the relief valve up form 2500psi to ~2800psi, and blew the pump within minutes. By the way, pumps aren't cheap. Maybe I was unlucky, or maybe you are all lucky. $700+ later, my system is set at 2500psi, which is the recommended pressure for the pump I have installed. If you decide to shim, I strongly recommend investing in a pressure gauge to check where you're at.
My limited personal experience is that pumps don't tolerate much over their rated pressure.
OkieG
glalonde
Bronze Member
Based on the JD online parts, the hydraulic pump is the same for the 790, 2210, 4100, 670, 770, 4110
The hydraulic pressure is not rated the same for all tractors.
For example, the 4110 is rated at 2418 max while the 790 is rated at 2050 max.
The hydraulic pressure is not rated the same for all tractors.
For example, the 4110 is rated at 2418 max while the 790 is rated at 2050 max.
BigEddy
Gold Member
- Joined
- Sep 6, 2002
- Messages
- 268
- Location
- Eastern Ontario
- Tractor
- JD 855, 322, AMT626 plus whatever my son dragged home this month
OkieG.
Do you notice a substantial difference with the 955 pump? I use my backhoe and loader much more than the PTO, so have plans to upgrade my pump. But I have not been "forced" into it like you were. I'd love to have more flow available for backhoe work. If I recall correctly, it's about a 30% increase in flow between the 2 pumps. Wondering if it is worth spending the money anyway.
Do you notice a substantial difference with the 955 pump? I use my backhoe and loader much more than the PTO, so have plans to upgrade my pump. But I have not been "forced" into it like you were. I'd love to have more flow available for backhoe work. If I recall correctly, it's about a 30% increase in flow between the 2 pumps. Wondering if it is worth spending the money anyway.
BigEddy
Gold Member
- Joined
- Sep 6, 2002
- Messages
- 268
- Location
- Eastern Ontario
- Tractor
- JD 855, 322, AMT626 plus whatever my son dragged home this month
Remember - any system is only as strong as its weakest link. Different models use different hoses, valves, and cylinders. Just because the pump is the same, doesn't mean the rest of the system can handle the same pressure. I like to think there is a reason why the maximum pressure was set where it was. Any good designer will build in some margin, but if we as users remove that margin, then we need to accept the risks as well.
OkieG
Veteran Member
<font color="blue"> the 4110 is rated at 2418 max while the 790 is rated at 2050 max. </font>
There you go. If the pump is the same part number, then you can safely shim to 2400psi on the 790. I say "safely", as in "shouldn't damage the pump". Buy a guage to check pressure...don't shim blindly.
OkieG
There you go. If the pump is the same part number, then you can safely shim to 2400psi on the 790. I say "safely", as in "shouldn't damage the pump". Buy a guage to check pressure...don't shim blindly.
OkieG
OkieG
Veteran Member
<font color="blue"> Do you notice a substantial difference with the 955 pump? </font>
Yes, it was worth it to me. It works just as you would expect with 25% more pressure and more flow....faster response and more power. 855 on steroids.
If you decide to tackle this project there is one more thing you should do while everything is apart. Replace the flow diverter valve with the 955 version. It is a machined cylinder that fits into the pressure relief valve housing.
A portion of total hyd. flow is diverted to power the power steering. The lower pump flow 855 has a 30/70 flow diverter, with 30% going to the steering. The 955 has a 20/80 diverter. The higher flow 955 pump needs to divert only 20% to have the same total flow for steering as 30% does for the 855 pump.
So, you get a bonus. Not only does the 955 pump flow more, but a higher percentage of flow goes for implement activity. Does that make sense? I not sure, but I believe that the steering flow is diverted even when you're not actively steering, so it's worth taking this extra step.
Some tractors have 2 separate pumps for steering and implements, but the x55 series has only one pump that shares the duty.
OkieG
Yes, it was worth it to me. It works just as you would expect with 25% more pressure and more flow....faster response and more power. 855 on steroids.
If you decide to tackle this project there is one more thing you should do while everything is apart. Replace the flow diverter valve with the 955 version. It is a machined cylinder that fits into the pressure relief valve housing.
A portion of total hyd. flow is diverted to power the power steering. The lower pump flow 855 has a 30/70 flow diverter, with 30% going to the steering. The 955 has a 20/80 diverter. The higher flow 955 pump needs to divert only 20% to have the same total flow for steering as 30% does for the 855 pump.
So, you get a bonus. Not only does the 955 pump flow more, but a higher percentage of flow goes for implement activity. Does that make sense? I not sure, but I believe that the steering flow is diverted even when you're not actively steering, so it's worth taking this extra step.
Some tractors have 2 separate pumps for steering and implements, but the x55 series has only one pump that shares the duty.
OkieG
