Farmerford
Platinum Member
- Joined
- Dec 9, 2006
- Messages
- 733
- Location
- Columbus, Georgia
- Tractor
- Kuborta B2400, L2900, L4330; Caterpillar D3B, John Deere 455D
Greg:
I had a slow afternoon and my daughter tried to teach me Powerpoint last weekend, so I doodled on your project in Powerpoint. The site will not let me upload Powerpoint directly, so I scanned the result and attached it (I hope) in pdf. I just looked and it blocked out the "balloon" that identifies the existing line from pump to three point hitch (dotted line) which is the one you are splicing into.
Here are my thoughts, based on my very limited experience. Your pump output of 3.5gpm suggests a small tractor. My Kubota B2400 HST is very small (24hp, they claim) and has about 4.7gpm pump output. Of that 4.7 gpm, about 1.7 gpm is priority flow to the steering and the remaining 3.0gpm flows first to the front end loader power beyond valve and then to the three point hitch. Nothing moves very fast, including the steering, but they move about as fast as I do, which is nothing a young man would brag about, but suits me just fine.
I recommend you consider a "variable" priority flow control valve because it allows you to adjust the amount of priority flow by must moving a lever on the valve. They don't cost any more than the "adjustable" priority flow control valve, and are much more convenient to adjust. There may be times when you want more or less flow to the steering, and the variable flow valve lets you fiddle with it as much as you want.
The second issue is the pressure relief for the power steering. The Prince variable flow control valves can be had with an internal pressure relief valve, but then the excess flow port must be connected to the reservoir rather than the downstream FEL valve, which makes the valve unsuitable for your purpose.
A separate PRV for the power steering circuit downstream of the flow control valve controlled flow doesn't add much cost or plumbing. Prince stand-alone PRVs are available in a 500-1500 psi range, while the built in PRV in the "adjustable" Prince flow divider may have a 1500-3000 range unless you special order it.
The third issue is the system PRV, meaning a PRV just downstream of the pump output, so that any blockage anywhere in the system will not deadhead the pump. Be sure your tractor has a system PRV and that you do not splice your steering and FEL in upstream of it.
Fourth, I don't think the 1000 psi PRV in the pump circuit will open unless you turn the steering wheel to full lock. Here is why. Suppose you have a load on the FEL that requires 2000 psi in the EF circuit to lift it. As the pressure builds in the EF circuit, flow will try to increase in the CF circuit above its setting (say 1gpm). The priority flow control valve will close the orifice in the controlled flow circuit as needed to keep the CF at 1gpm regardless of the pressure in the CF circuit. The pressure at the CF port will be only return line pressure because the 1gpm flows (relatively) unimpeded through the open center steering valve and on to the reservoir.
Fifth, your FEL control valve should have power beyond to avoid excessive back pressure on the spool o-rings from the downstream TPH. Most two spool loader valves have power beyond, though you may have to spend an extra $30 for the power beyond sleeve that activates this feature.
Lastly, a 0-3000psi pressure gauge costs less than $20 and the tee to insert it in costs less than $5. That $25 installation in the steering circuit just prior to the steering valve will let you set the steering PRV to the exact setting you choose. It is not likely that it will come from Prince set at exactly the 1000psi you desire.
It sounds like a fun project, though I predict you will be surprized at the total cost (hoses, fittings, etc. will be a large percentage of the total) and the complexity of the plumbing.
Gobble Gobble.
I had a slow afternoon and my daughter tried to teach me Powerpoint last weekend, so I doodled on your project in Powerpoint. The site will not let me upload Powerpoint directly, so I scanned the result and attached it (I hope) in pdf. I just looked and it blocked out the "balloon" that identifies the existing line from pump to three point hitch (dotted line) which is the one you are splicing into.
Here are my thoughts, based on my very limited experience. Your pump output of 3.5gpm suggests a small tractor. My Kubota B2400 HST is very small (24hp, they claim) and has about 4.7gpm pump output. Of that 4.7 gpm, about 1.7 gpm is priority flow to the steering and the remaining 3.0gpm flows first to the front end loader power beyond valve and then to the three point hitch. Nothing moves very fast, including the steering, but they move about as fast as I do, which is nothing a young man would brag about, but suits me just fine.
I recommend you consider a "variable" priority flow control valve because it allows you to adjust the amount of priority flow by must moving a lever on the valve. They don't cost any more than the "adjustable" priority flow control valve, and are much more convenient to adjust. There may be times when you want more or less flow to the steering, and the variable flow valve lets you fiddle with it as much as you want.
The second issue is the pressure relief for the power steering. The Prince variable flow control valves can be had with an internal pressure relief valve, but then the excess flow port must be connected to the reservoir rather than the downstream FEL valve, which makes the valve unsuitable for your purpose.
A separate PRV for the power steering circuit downstream of the flow control valve controlled flow doesn't add much cost or plumbing. Prince stand-alone PRVs are available in a 500-1500 psi range, while the built in PRV in the "adjustable" Prince flow divider may have a 1500-3000 range unless you special order it.
The third issue is the system PRV, meaning a PRV just downstream of the pump output, so that any blockage anywhere in the system will not deadhead the pump. Be sure your tractor has a system PRV and that you do not splice your steering and FEL in upstream of it.
Fourth, I don't think the 1000 psi PRV in the pump circuit will open unless you turn the steering wheel to full lock. Here is why. Suppose you have a load on the FEL that requires 2000 psi in the EF circuit to lift it. As the pressure builds in the EF circuit, flow will try to increase in the CF circuit above its setting (say 1gpm). The priority flow control valve will close the orifice in the controlled flow circuit as needed to keep the CF at 1gpm regardless of the pressure in the CF circuit. The pressure at the CF port will be only return line pressure because the 1gpm flows (relatively) unimpeded through the open center steering valve and on to the reservoir.
Fifth, your FEL control valve should have power beyond to avoid excessive back pressure on the spool o-rings from the downstream TPH. Most two spool loader valves have power beyond, though you may have to spend an extra $30 for the power beyond sleeve that activates this feature.
Lastly, a 0-3000psi pressure gauge costs less than $20 and the tee to insert it in costs less than $5. That $25 installation in the steering circuit just prior to the steering valve will let you set the steering PRV to the exact setting you choose. It is not likely that it will come from Prince set at exactly the 1000psi you desire.
It sounds like a fun project, though I predict you will be surprized at the total cost (hoses, fittings, etc. will be a large percentage of the total) and the complexity of the plumbing.
Gobble Gobble.
