Jerky project cylinder action
- Thread starter yarg
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J_J
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If the pump can put out 20 GPM's, and your cyl valve is only passing about 3 GPM's to the cyl, at full stroke, how much fluid is passing through the relief.
The intent here is to show that it is not about the pressure.
2 in bore
1 in shaft
3000 psi pump
If you adjust the relief valve down to 1500 psi, you can still lift about 9,425 lbs
I don't think you will be lifting anything close to that weight.
If those hyd motors are 1500 psi motors, then you need to set the hyd motor valve relief at about 1450 psi. That is solely to protect the motor.
The motor valve relief valve will set the max relief for any valve downstreal. The fluid then flows to the ram valve, where the ram relief valve can be set anywhere below the main relief valve. Some reliefs can be set from 500 psi to 3000 psi.
Another point here is that if the hyd motors are using all the pump flow, there is none left for the ram.
The two spool motor valve has priority.
The intent here is to show that it is not about the pressure.
2 in bore
1 in shaft
3000 psi pump
If you adjust the relief valve down to 1500 psi, you can still lift about 9,425 lbs
I don't think you will be lifting anything close to that weight.
If those hyd motors are 1500 psi motors, then you need to set the hyd motor valve relief at about 1450 psi. That is solely to protect the motor.
The motor valve relief valve will set the max relief for any valve downstreal. The fluid then flows to the ram valve, where the ram relief valve can be set anywhere below the main relief valve. Some reliefs can be set from 500 psi to 3000 psi.
Another point here is that if the hyd motors are using all the pump flow, there is none left for the ram.
The two spool motor valve has priority.
Yes, JJ,
I have all of that. I have the motor spool valves set at their lowest, 1500 PSI setting therefore the rest of the circuit is protected pressure. The down stream valve for the ram is going to get a 500-1500psi adjustable relief that I will set just high enough for the load on the ram, when the ram is full and during the filling excess oil can then go through this relief valve to the tank. This should not overload the pressure and engine HP from the pump? The pump is rated up to 2300 PSI and 23 or 25 GPM max? I got it from Surplus center like much of the other parts.
I never want to use the ram at the same time as the motors so that is not a factor. The last thing I want is to have pipe in the ground and have someone activate the mast ram
Bad ju ju. So I put an integrated lock on the ram when fully vertical.
I am looking at needing about 1200 ponds of force to lift or lower the mast so 500 PSI will be more than enough?
Gray
I have all of that. I have the motor spool valves set at their lowest, 1500 PSI setting therefore the rest of the circuit is protected pressure. The down stream valve for the ram is going to get a 500-1500psi adjustable relief that I will set just high enough for the load on the ram, when the ram is full and during the filling excess oil can then go through this relief valve to the tank. This should not overload the pressure and engine HP from the pump? The pump is rated up to 2300 PSI and 23 or 25 GPM max? I got it from Surplus center like much of the other parts.
I never want to use the ram at the same time as the motors so that is not a factor. The last thing I want is to have pipe in the ground and have someone activate the mast ram
Bad ju ju. So I put an integrated lock on the ram when fully vertical. I am looking at needing about 1200 ponds of force to lift or lower the mast so 500 PSI will be more than enough?
Gray
bigdeano
Platinum Member
j-j,
This must be a quiz. OK. yarg, no cheating by looking at my answers, LOL
1. Not very much, too many variables to give a number. Seal drag, pressure drop in pipes, valves, etc.
2. Whatever pressure the relief valve is set at. If there's no relief valve, whatever pressure it takes to break the weakest part or stall the prime mover.
3. To protect the pump and other system components from excessive pressure.
How'd I do
Darn, I was too slow typing.
This must be a quiz. OK. yarg, no cheating by looking at my answers, LOL
1. Not very much, too many variables to give a number. Seal drag, pressure drop in pipes, valves, etc.
2. Whatever pressure the relief valve is set at. If there's no relief valve, whatever pressure it takes to break the weakest part or stall the prime mover.
3. To protect the pump and other system components from excessive pressure.
How'd I do
Darn, I was too slow typing.
bigdeano,
I think you aced it! Better answers than mine but the same concepts. I said in the beginning that I am a beginner and it shows but I am a quick study most often? I am not as much a technician in my terms but I do get the ideas.
My biggest confussion is on the proportioning valve option. If the excess flow is or is not subject to a pressure relief valve in such a unit? No matter whether I go to such a modification or not, I would like to know----the learner in me. I am not ashamed of learning from anyone who offers information. Healthy for me.
I think you aced it! Better answers than mine but the same concepts. I said in the beginning that I am a beginner and it shows but I am a quick study most often? I am not as much a technician in my terms but I do get the ideas.
My biggest confussion is on the proportioning valve option. If the excess flow is or is not subject to a pressure relief valve in such a unit? No matter whether I go to such a modification or not, I would like to know----the learner in me. I am not ashamed of learning from anyone who offers information. Healthy for me.
bigdeano
Platinum Member
By having the motor running yarg is limiting the pressure available to the ram to the back pressure developed by the motor. If the motor was under load there would be more pressure available to the ram.
bigdeano
Platinum Member
Technically, the excess flow does go thru a relief valve, but the pressure of that valve is controlled by the flow in the controlled flow port. The flow out the excess flow port has to be restricted to develop pressure for the controlled flow port, otherwise all the flow would just go to the tank, if that's where it's hooked to.
The excess flow port can be used to power another circuit as well.
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Mace Canute
Elite Member
I think the problem may be more about flow and (lack of) flow capacity then "pressure".
yarg, what happens when you extend and retract the lift cylinder at both full throttle and at an idle with the lift control valve at maximum both ways and also the same test "feathering" the lift control valve?
yarg, what happens when you extend and retract the lift cylinder at both full throttle and at an idle with the lift control valve at maximum both ways and also the same test "feathering" the lift control valve?
OK,, so what you are explaining is that this sort of valve has it's own relief built in? Then you would have anything back of that valve at the pressure of that relief and that means that for any of the excess flow to get through the valve, it would have to be at that pressure?
So a proportioning valve does split the flow between a working port and a return port but the pressure upstream of both will be subject to the relief of the built in portion of this valve? This makes sense as from one written discription, it seamed that there would be high pressure upstream of the working port and into the actuated device but no pressure upstream of the flow through port. This did not make sense to me as in my mind, any upstream pressure must be present to the working port load and the overflow port.
Did I explain it right? Quiz two for me, or maybe five?
So a proportioning valve does split the flow between a working port and a return port but the pressure upstream of both will be subject to the relief of the built in portion of this valve? This makes sense as from one written discription, it seamed that there would be high pressure upstream of the working port and into the actuated device but no pressure upstream of the flow through port. This did not make sense to me as in my mind, any upstream pressure must be present to the working port load and the overflow port.
Did I explain it right? Quiz two for me, or maybe five?
MC,
Well, no matter the throttle point the engine is stalled. The valve would just bearly be able to handle the flow at high RPM and the pressure at any speed is such that it would reguire HP to work because the ram volume is so small that it fills or looks full to the flow as soon as you trigger it.
Feathering is almost impossible. The only way I could get good action was running a motor ( taking most of the flow away to the tank ) while valving the ram. In taking most of the flow away, I could throttle the flow to a lower pressure than the spool relief valve. Given this info. I decided that my first attempt at a change is to get the low pressure relief and a needle for flow control?
Well, no matter the throttle point the engine is stalled. The valve would just bearly be able to handle the flow at high RPM and the pressure at any speed is such that it would reguire HP to work because the ram volume is so small that it fills or looks full to the flow as soon as you trigger it.
Feathering is almost impossible. The only way I could get good action was running a motor ( taking most of the flow away to the tank ) while valving the ram. In taking most of the flow away, I could throttle the flow to a lower pressure than the spool relief valve. Given this info. I decided that my first attempt at a change is to get the low pressure relief and a needle for flow control?
J_J
Super Star Member
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If you limit the GPM's going to the ram valve to 2 or 3 GPM's you will not have a problem.
You should use the valve I suggested, to provide a regulated flow to say 3 GPM, and be done with it.
You can put this valve before any other valves, and the priority flow feeds the ram, and the excess flow goes to the hyd motors.
The out put from the priority flows goes to the IN port of the ram.
The output from the excess flow will go to the two spool hyd motor valve.
You should use the valve I suggested, to provide a regulated flow to say 3 GPM, and be done with it.
You can put this valve before any other valves, and the priority flow feeds the ram, and the excess flow goes to the hyd motors.
The out put from the priority flows goes to the IN port of the ram.
The output from the excess flow will go to the two spool hyd motor valve.
bigdeano
Platinum Member
Your second paragraph seems correct to me. The valve just functions to restrict the flow out the excess flow port until the required flow is reached out the controlled flow port.
The best way is to not worry about pressure with these valves, they're all about flow. All the pressure balances inside that make them work the user doesn't need to think about.
OK,
So both of you Gentlemen are telling me that while there is a bit of a relief setting to them, they actually internally will allow more or less pressure to the excess flow port based upon how much flow rather than pressure goes to the work port. Well, this changes things a bit. If I have these fine details right now it means that:
While my ram valve may need 600PSI, this valve special may pass the bulk of the flow at maybe 600 psi to allow the small amount to go to the ram valve to satisfy the 600 psi and max of maybe 3 gpm flow so the back pressure on the system does not have to be all at this valves working port pressure? Or maybe the back pressure would be what ever the ram vlave pressure would be? 600 PSI? In rethinking this, the upstream pressure has to be the needed working pressure and no less!!!!! It can not be 200 upstream if 600 is needed at the working port.
An earlier writer in his explanation left me with the impression that there would be no back pressure on the system through the excess port? That did not seam possible so I went with the thought of full back pressure of the relief valve more than a raw flow volume. It can be difficult to explain things in words even when you know what is going on.
So both of you Gentlemen are telling me that while there is a bit of a relief setting to them, they actually internally will allow more or less pressure to the excess flow port based upon how much flow rather than pressure goes to the work port. Well, this changes things a bit. If I have these fine details right now it means that:
While my ram valve may need 600PSI, this valve special may pass the bulk of the flow at maybe 600 psi to allow the small amount to go to the ram valve to satisfy the 600 psi and max of maybe 3 gpm flow so the back pressure on the system does not have to be all at this valves working port pressure? Or maybe the back pressure would be what ever the ram vlave pressure would be? 600 PSI? In rethinking this, the upstream pressure has to be the needed working pressure and no less!!!!! It can not be 200 upstream if 600 is needed at the working port.
An earlier writer in his explanation left me with the impression that there would be no back pressure on the system through the excess port? That did not seam possible so I went with the thought of full back pressure of the relief valve more than a raw flow volume. It can be difficult to explain things in words even when you know what is going on.
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JJ,
If I order one of these, I will get the one that is 1.5 GPM as I do not need any speed on this ram, just even slow flow. I will look into it tomorrow.
I would likely do this on the input side of the ram spool. Pipe the working port to the spool and the excess to the tank. This allows full flow at all times to go to motors and then after those, a split flow to the ram spool?
If I order one of these, I will get the one that is 1.5 GPM as I do not need any speed on this ram, just even slow flow. I will look into it tomorrow.
I would likely do this on the input side of the ram spool. Pipe the working port to the spool and the excess to the tank. This allows full flow at all times to go to motors and then after those, a split flow to the ram spool?
Mace Canute
Elite Member
Hmmmm. Over the years I have operated a lot of hydraulic equipment from tractors on the farm to radial arm diggers and bucket trucks and I never had an instance that matched your situation. I have never encountered a hydraulic valve that I couldn't feather although some were indeed touchy.
Trouble shooting can often be facilitated by isolating sections of the system.
Have you tried using a different hose than is connected to the lift cylinder to make a loop between the in and out ports on the lift control valve? If nothing changes, you have eliminated any problem with the cylinder and hoses and the raising/lowering mechanism but if everything works great you've narrowed it down to the lift cylinder and hoses and the the raising/lowering mechanism.
The next step would be disconnecting the ram and cycle it in and out. If things are great then you might have a bind in the raising/lowering mechanism. If things remain the same look for a problem with the hoses or cylinder. Is there an unseen kink in a line? It's rare but sometimes the inner lining can become detached and fold over on itself causing a severe restriction to flow.
If nothing changes after the loop test, I would run two open ended lines from the lift control valve to a very clean bucket to catch the reusable oil and see what happens. If you still have a problem I would have to think it's in the valve itself and it would likely need replacing to make sure.
If you can't narrow it down after jumping through all those hoops...well, as they say, we'll cross that bridge when we get to it.
Trouble shooting can often be facilitated by isolating sections of the system.
Have you tried using a different hose than is connected to the lift cylinder to make a loop between the in and out ports on the lift control valve? If nothing changes, you have eliminated any problem with the cylinder and hoses and the raising/lowering mechanism but if everything works great you've narrowed it down to the lift cylinder and hoses and the the raising/lowering mechanism.
The next step would be disconnecting the ram and cycle it in and out. If things are great then you might have a bind in the raising/lowering mechanism. If things remain the same look for a problem with the hoses or cylinder. Is there an unseen kink in a line? It's rare but sometimes the inner lining can become detached and fold over on itself causing a severe restriction to flow.
If nothing changes after the loop test, I would run two open ended lines from the lift control valve to a very clean bucket to catch the reusable oil and see what happens. If you still have a problem I would have to think it's in the valve itself and it would likely need replacing to make sure.
If you can't narrow it down after jumping through all those hoops...well, as they say, we'll cross that bridge when we get to it.
bigdeano
Platinum Member
The back pressure on the system and the pump will be equal to the pressure on the working port. You can't get more pressure out of this valve than you put in.
With 1.5 gpm it will take 7.6 seconds to fully extend the ram. You can buy the adjustable flow valves cheaper and set any speed you want.
JJ,
I will use the parts that I ordered anyhow but if they alone do not solve this issue then I will order the valve you mention. I do understand that it would be best to proportion the excess to the flow from this valve to the motor spool and the priority flow to the ram valve then all should work
Thank you for your patience on this issue. I now have a better understanding of some of these devices. I did google the device but what I got to read was not too well done and the symbols were foreign to me?
Bigdeano,
Yes, both of you are right and I finally got the take on the propotioning valve. As such a valve would be more costly and bulky and I would still want to set a fill rate with the needle vlave, this is the way I am going at first along with the change in relief catradge to drop the pressure. If all goes well, I should have a pump that does not stall out and a slow filling ram that is not jerky or dangerous?
In fact to tilt the ram up the slow is good but to bring it back down, slowere is even better but the down speed would be much greater as the ram rod is 1.25 " so the fill volume is much less, much less. I am hoping the needle valve will regulate by default the down speed as well being that the oil has to exit through it to allow the ram to shorten up.
Parts to show up on wednesday and then a report on the saga?
Thank you all and keep the info coming
I love to learn!Gray---oh and this is my name---the color. Few believe me so I reverse the letters just for fun
J_J
Super Star Member
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yarg.
You seem hung up on the hyd pressure for the ram.
The ram is going to develop the pressure it needs to lift or use the load.
Whatever relief you put in the valve, will limit the load capability, or you will see the relief pressure if you hold the lever down long enough.
You could work that ram all day and never see relief pressure.
The hyd motors will develop the pressure they need for the load they are working also. If you are not working them hard, you may never see relief pressure.
Pressure is what it is, and is variable with load. Vary the load and the pressure changes accordingly..
Vary the GPM's of the pump and the speed of the motors will change accordingly.
You seem hung up on the hyd pressure for the ram.
The ram is going to develop the pressure it needs to lift or use the load.
Whatever relief you put in the valve, will limit the load capability, or you will see the relief pressure if you hold the lever down long enough.
You could work that ram all day and never see relief pressure.
The hyd motors will develop the pressure they need for the load they are working also. If you are not working them hard, you may never see relief pressure.
Pressure is what it is, and is variable with load. Vary the load and the pressure changes accordingly..
Vary the GPM's of the pump and the speed of the motors will change accordingly.
CJONE
Veteran Member
Sorry, long weekend. We are both, we build hydraulic packages and help with equipment building. The ones that I will be building will be custom for a pipe handler. I don't want anyone getting "happy fingers" so they will be inside a fitting at the cylinder base. just in case a line blows both cylinders will come down at the same rate. I cannot rely on P/O check because the unlock at different pressures and that would cause too much twisting and damage the unit. CJ
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