Do I have too big of a pump?
- Thread starter Billy_PA
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Gentlemen.
Thank you very much for all of your replys. Very very much appricated. I will try to answer everyone in this single post.
J_J: It does not feel like I dont have enough HP to run this pump, it wont stall the engine, it bogges down in RPM but never stall. But maybe it should not even bogg down?
Farmerford: sounds like a very good root cause for my problem. As many other also have mentioned I should go trough my lines for restriction (size)
AKKAMAN:
Thank you for the advice on the gauge. Where should I install this?
Do you think If I installed a PRV which is specified for the flow and having the tractor pressure lines change too a larger cross would help me? The FEL lines are hard pipes mainly, not so easy to change these. Or do you think this would be a waste of money and time?
The flow is rated at 2500 rpm. My HP is rated at 2300 rpm.
Transit: Great documents, thank you!
Thank you very much for all of your replys. Very very much appricated. I will try to answer everyone in this single post.
J_J: It does not feel like I dont have enough HP to run this pump, it wont stall the engine, it bogges down in RPM but never stall. But maybe it should not even bogg down?
Farmerford: sounds like a very good root cause for my problem. As many other also have mentioned I should go trough my lines for restriction (size)
AKKAMAN:
Thank you for the advice on the gauge. Where should I install this?
Do you think If I installed a PRV which is specified for the flow and having the tractor pressure lines change too a larger cross would help me? The FEL lines are hard pipes mainly, not so easy to change these. Or do you think this would be a waste of money and time?
The flow is rated at 2500 rpm. My HP is rated at 2300 rpm.
Transit: Great documents, thank you!
AKKAMAAN
Veteran Member
You add it because you want it to kick in huh??? Set the new prv valve slightly lower than the FEL prv....if the FEL prv valve "kicks in", then the new prv is either undersized or not set low enough (or FEL prv high enough) keep 100-200psi pressure setting between the two prv's
Gauge need to be plumbed in between pump and first next valve....
I still think this pump change is a BAD move.....as stated earlier....you are trying to extract more hydraulic power than engine can provide....and lowering rpm's sure do lower flow, but it also lower the engine power....so thats not the solution on your problems either.....but to try to do the best out if the mess.....make my suggested pressure test...that should tell some about the future of this....
I think changing pump size this drastically is like adding a ticking bomb.....out of control....YOU BETTER BE SAFE DOING ALL THIS THINGS!!!
J_J
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One side note to consider, is that you may be using the tractor for a couple of hours, and occasionally you may cause the pressure to build up to the max. As you probably know, the pressure only builds against the load you put on the system. Just raising the FEL arms only requires a couple of hundred lbs. About the only time you see max pressure is when lifting a full bucket at max weight, and then only briefly, and when at the end of cyl travel. If you could ever run a paper graph on the hyd pressure, I think you would be surprised as to the amount of pressure used at different times. However, you can install a gage in the system and monitor the pressure. When you hear the relief valves whining, you know you are up to the relief pressure. You probably have noticed that things on your tractor work much faster now due to the increased volume of fluid. Even if you reduce the rpm's to reduce the flow, you also reduce the HP. I don't see you having trouble unless the reliefs stay on for extended times. You really did not increase the power of the hyd system by going to a larger pump, unless the pump has a higher pressure rating. If you were to change any lines to match the flow velocity, you would have to change all the pressure lines in that circuit.
J_J
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As far as the rpm decreasing when trying to curl a bucket under load, you have asked the hyd system to run at max pressure, and when the relief valve kicks in, the only path for the fluid to go is out the relief valve, and at the same time, you have asked the engine to produce max HP. At idle and trying to load up a bucket, same thing, when the pressure gets to max, the engine will struggle to maintain rpms. Just use what you have in a logical manner. If you want more force, that would require larger cylinders, and that is only if the front end of the tractor can handle the increased force/load
Last edited:
David Devuono
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Maybe we should know more about this dump trailer? It must be HD with dual dump cylinders. A 24HP tractor probably is in the 2000 pound range. In my area a 17 year old lost his life recently. They determined he was pulling a wagon with 4000 pounds of hay and it overwhelmed his tractor. Hopefully you are in a flat area.
Billy, maybe you will have a clearer picture if I explain pump problem I was having with my Jinma254.
I was using the FEL heavily for ground work; I ended up replacing pumps every 50-100 hours. The pump bearings would burnout and the gears would cut into the pump body. The first replacement maybe a bad pump, number 2 another bad pump. Number 3 and 4? Something is fundamentally wrong.
At first I did not find any reasons for the pump failures, and then I noticed that the pump part number in the tractor manual although correct was different from other 254 pumps. The difference was due to the flow rate, the pumps that were failing are rated at 8.5 GPM and the others rated at 3.5 GPM. The up graded pump was for slow response. However, reverse engineering the system reveled major system @%&%$#. All the hydraulic lines were sized for a 3.5 GPM pump and to make matters worse, the tractor uses metric lines and the FEL uses inch lines. What is in-between? Adaptors. Installing a pressure gauge at the pump output showed that there was a constant load of 500-600 psi the pump was working aginst just pushing oil around the system.
Using the Hydraulic Nomographs I replaced all the pressure lines with 1/2 inch ID lines, removed all the adaptors to run direct lines, meaning that one end fitting is inch and one is metric. Replaced the suction, pressure relief valve and sump return with 1 inch ID lines. Now the oil is 30 deg cooler and no more blown pumps.
I was using the FEL heavily for ground work; I ended up replacing pumps every 50-100 hours. The pump bearings would burnout and the gears would cut into the pump body. The first replacement maybe a bad pump, number 2 another bad pump. Number 3 and 4? Something is fundamentally wrong.
At first I did not find any reasons for the pump failures, and then I noticed that the pump part number in the tractor manual although correct was different from other 254 pumps. The difference was due to the flow rate, the pumps that were failing are rated at 8.5 GPM and the others rated at 3.5 GPM. The up graded pump was for slow response. However, reverse engineering the system reveled major system @%&%$#. All the hydraulic lines were sized for a 3.5 GPM pump and to make matters worse, the tractor uses metric lines and the FEL uses inch lines. What is in-between? Adaptors. Installing a pressure gauge at the pump output showed that there was a constant load of 500-600 psi the pump was working aginst just pushing oil around the system.
Using the Hydraulic Nomographs I replaced all the pressure lines with 1/2 inch ID lines, removed all the adaptors to run direct lines, meaning that one end fitting is inch and one is metric. Replaced the suction, pressure relief valve and sump return with 1 inch ID lines. Now the oil is 30 deg cooler and no more blown pumps.
J_J
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Billy_PA
Here is a velocity chart to help you choose a hose .
http://www.gates.com/downloads/download_common.cfm?file=NomographicChart.pdf&folder=brochure
According to the chart, 1/2 would be OK, but there is a window for any variance.
The diagram also reflects an oil viscosity of about 315 SSU at 100 degrees or 68 CST
Here is a velocity chart to help you choose a hose .
http://www.gates.com/downloads/download_common.cfm?file=NomographicChart.pdf&folder=brochure
According to the chart, 1/2 would be OK, but there is a window for any variance.
The diagram also reflects an oil viscosity of about 315 SSU at 100 degrees or 68 CST
Gentlemen. You are all very helpful.
Transit: Thank you very must for your story/information Did you also replaced your loader lines? And to a more flow PRV or just the PRV line size ?
J_J: Thank you for your explanation and the chart. My intention with the pump upgrade was to get the increase in speed not the force. According to the dealer the only difference between the pump is the flow out put, pressure rating is the same.
AKKAMAN: Yes the pressure test is next on the to do list of mine.
Transit: Thank you very must for your story/information Did you also replaced your loader lines? And to a more flow PRV or just the PRV line size ?
J_J: Thank you for your explanation and the chart. My intention with the pump upgrade was to get the increase in speed not the force. According to the dealer the only difference between the pump is the flow out put, pressure rating is the same.
AKKAMAN: Yes the pressure test is next on the to do list of mine.
