Hydro Steering Feedback

[93blackxj]

So I have a question for those with more knowledge on orbital valves that I do. I am trying to figure out if there can be anything done to help feedback to the steering wheel in my hydro system without completely changing my setup. My setup works well and I am happy with its operation and speed for what it is but would like to try to keep the wheel from getting ripped out of my hands from hard hits to the tires.

I understand that this happens when an external force is applied to the wheels that is greater than the force created by the pump/steering cylinder. So obviously a higher pressure pump or larger bore cylinder would help this but that is not what I am after if I can help it. Specs of my system are listed below. I run a load reaction orbital and would like to keep it that way to keep some of the "driving" feel.

-Stock XJ TC pump with enlarged pressure relief valve orifice
-4.5" PSC pulley
-1/2" feed line to orbital and 3/8" feed to cylinder
-6.0 ci midwest steering load reaction orbital
-2.5" x 8" Surplus center DE cylinder

I have found an orbital from eaton that can be ordered with internal inlet check valves, that seem to be what I need, to reduce the steering kickback but wondering if just adding a check valve to each inlet at the orbital will do the same thing? Just not sure if this would effect the feel of the load reaction characteristics or have any effect at all since it is external of the orbital. The young powertech one that I found is an external unit that bolts onto the orbital, so not sure what all it has going on for the check valves. Here are pictures of what I found. Any input would be appreciated!

 

[Bebop]

You can't do the 2 check valves. It will prevent the ram from retracting.
This is to be used in the orbital inlet circuit to protect the pump.

 

[93blackxj]

You can't do the 2 check valves. It will prevent the ram from retracting.
This is to be used in the orbital inlet circuit to protect the pump.

Thats what I figured but trying to figure out how the eaton orbital that you can order with inlet check valves works and still lets fluid return to the orbital. I guess its done internally with some type of internal pilot that lets fluid return when pressurized from the pump side but doesnt let it backfeed from pressure created by the cylinder from external force on the tires. Just wondering if there is some type of external valve or counterbalance I could add to the system that does the same thing.

 

[Provience]

Nobody complains about driving feel in drive by wire setups, well, most people dont.

Run a wavy spring so you can adjust the tension on the steering wheel for resistance if the steering valve spring isn't enough, you'll still get feedback from the tires and suspension

 

[93blackxj]

http://www.eaton.com/ecm/groups/public/@pub/@eaton/@hyd/documents/content/pct_273743.pdf


I found this cross port relief valve that I believe is something like I would need but don't know enough about hydraulics to confirm

 

[93blackxj]

Nobody complains about driving feel in drive by wire setups, well, most people dont.

Run a wavy spring so you can adjust the tension on the steering wheel for resistance if the steering valve spring isn't enough, you'll still get feedback from the tires and suspension

🤣🤣 sounds like a good plan to me

 

[Provience]

http://www.eaton.com/ecm/groups/public/@pub/@eaton/@hyd/documents/content/pct_273743.pdf


I found this cross port relief valve that I believe is something like I would need but don't know enough about hydraulics to confirm

Tough part about cross port relief is that it won't bypass any but the most extreme spikes, too soft and you'd wonder why the car was constantly or often under steering or failing to hold a turn

Too firm and it would still be a knuckle snapper

 

[HYDRODYNAMIC]

You can not add check valves or pilot operated check valves as they will block the feedback and make your steering orbital feel like a non feedback.

There is this setup as an option to reduce harshness as well as cross port relief. Read the quote below for more info.

From the power steering thread:

My understanding is that the cylinder to valve lines are T'd into the two accumulators. Not the pressure or return lines on the valve or pump. One for left, one for right. The pressure is set at 460PSI. The DSC normally adds compression valving on entering fluid and free flows on return. With 460PSI keeping the oil out of the accumulator. There is no oil bypassing into the accumulators while steering with light force. When the force from an impact to the tires spikes the pressure, the oil will flow through the DSC burning up energy and dampening the tire movement, the oil will then flow into the accumulator to allow the tires to turn and react to the terrain, eventually the pressure will build high enough in the accumulator and equal the force at the tires and when the force at the tires is gone or has past the accumulator will push out the oil and move the tires back into the position.
This will create a cushion as well as slop between the tires and the steering wheel under high force when used in the rocks when the steering system is seeing high pressure. When going high speed when light steering input is needed, the 460PSI is high enough that the accumulators will not be functional and there will be no slop or cushion. Both of the applications mentioned are on trophy trucks, not rock racers. I am interested how the system performs at slow speed in the rocks and if it is still useful or if the slop is too great.

I used a similar form to this function on my old hydraulic buggy. The part is called a cross port relief valve. When the tires see an impact that creates a pressure spike the oil will dump over a relief valve burning up energy and fill the other side of the cylinder. This creates the same cushion and dampening effect. The difference is the cylinder can bypass all the way from left to right and there is no accumulator to max out and go solid. So you have more dampening. The pressure relief valves in the cross port relief block can be adjusted to crack at higher pressure than the 460 PSI so they would not open and create slop unless you really hit something hard, then with the higher pressure and unlimited flow they could burn up more energy through dampening.
The accumulator style keeps the oil on one side of the cylinder so if you hold the steering wheel straight the tires will move and return to center. The cross port relief style moves the oil from one side to the other side of the cylinder so if you hold the steering wheel straight the tires will move and you will have to turn the steering wheel to center up the tires after the impact.
It would be one of those things that is up to the drivers feel on how it performed. On my new buggy I did not feel like it was worth it to plumb in a cross port relief. It is very easy to add if I feel like I am crashing into rocks all the time and need a cushion, but I don't think I will be driving that way.
One thing to add is that a cross port relief if a good safety device to limit line pressure so hoses, orbitals, and cylinders do not burst. I believe that some have blown up the Sweet steering valves from over pressuring due to wheel impacts. So there is a known need in racing to cushion the impacts with some sort of energy absorption.

 

[93blackxj]

You can not add check valves or pilot operated check valves as they will block the feedback and make your steering orbital feel like a non feedback.

There is this setup as an option to reduce harshness as well as cross port relief. Read the quote below for more info.

From the power steering thread:

My understanding is that the cylinder to valve lines are T'd into the two accumulators. Not the pressure or return lines on the valve or pump. One for left, one for right. The pressure is set at 460PSI. The DSC normally adds compression valving on entering fluid and free flows on return. With 460PSI keeping the oil out of the accumulator. There is no oil bypassing into the accumulators while steering with light force. When the force from an impact to the tires spikes the pressure, the oil will flow through the DSC burning up energy and dampening the tire movement, the oil will then flow into the accumulator to allow the tires to turn and react to the terrain, eventually the pressure will build high enough in the accumulator and equal the force at the tires and when the force at the tires is gone or has past the accumulator will push out the oil and move the tires back into the position.
This will create a cushion as well as slop between the tires and the steering wheel under high force when used in the rocks when the steering system is seeing high pressure. When going high speed when light steering input is needed, the 460PSI is high enough that the accumulators will not be functional and there will be no slop or cushion. Both of the applications mentioned are on trophy trucks, not rock racers. I am interested how the system performs at slow speed in the rocks and if it is still useful or if the slop is too great.

I used a similar form to this function on my old hydraulic buggy. The part is called a cross port relief valve. When the tires see an impact that creates a pressure spike the oil will dump over a relief valve burning up energy and fill the other side of the cylinder. This creates the same cushion and dampening effect. The difference is the cylinder can bypass all the way from left to right and there is no accumulator to max out and go solid. So you have more dampening. The pressure relief valves in the cross port relief block can be adjusted to crack at higher pressure than the 460 PSI so they would not open and create slop unless you really hit something hard, then with the higher pressure and unlimited flow they could burn up more energy through dampening.
The accumulator style keeps the oil on one side of the cylinder so if you hold the steering wheel straight the tires will move and return to center. The cross port relief style moves the oil from one side to the other side of the cylinder so if you hold the steering wheel straight the tires will move and you will have to turn the steering wheel to center up the tires after the impact.
It would be one of those things that is up to the drivers feel on how it performed. On my new buggy I did not feel like it was worth it to plumb in a cross port relief. It is very easy to add if I feel like I am crashing into rocks all the time and need a cushion, but I don't think I will be driving that way.
One thing to add is that a cross port relief if a good safety device to limit line pressure so hoses, orbitals, and cylinders do not burst. I believe that some have blown up the Sweet steering valves from over pressuring due to wheel impacts. So there is a known need in racing to cushion the impacts with some sort of energy absorption.

Thank you for the info. This is something that has also been mentioned to me before and wondered if it would help with some of the feedback. I figured that the cross port valve would achieve what I am trying to do but wondered how it would behave in the rocks when high steering force is needed. I think it would be tough finding a happy medium setting to where it bypassed under hard hits but stays engaged when you are in a bind in the rocks.

The accumulator seems like an interesting setup and I would also like to know how it behaved in the rocks. I wonder with the accumulator setup if it would eventually build up enough pressure to "catch up" if the tires are bound up and give an extra burst of pressure to overcome, or if it would just continue to bypass while free wheeling the steering wheel with no steering output.

 

[ScottRS]

What you're finding is why I prefer non-reactive steering valves for mostly-crawling applications. They're more interesting to drive at speed, and not flat-tow-friendly, but the yank-from-hands while crawling, just doesn't happen.

In theory, it'd be possible to add pilot lock valves to the cylinder hoses, and bypass valves for those, to build something that has selectable reactivity. Turn off the bypass and force everything through pilot lock valves, piloted off of the steering input line, and you can steer when you want, but if you're not trying to steer, the lock valves will hold it where it is. Open the bypass valves to put it back to normal. You'd want a fairly low pilot trigger pressure as this system would be somewhat having to fight itself in low-force-needed steering situations, and it'd be interesting to get it dialed in.

Also in theory, you can change the reactivity profile by changing the leaf springs in the steering valve. In reality, those springs aren't available separately, so you'd be doing a lot of trial-n-error to find compatible springs and dial it into something you like.

You're at one of those points where... try it and see.

 

[HYDRODYNAMIC]

What you're finding is why I prefer non-reactive steering valves for mostly-crawling applications. They're more interesting to drive at speed, and not flat-tow-friendly, but the yank-from-hands while crawling, just doesn't happen.

In theory, it'd be possible to add pilot lock valves to the cylinder hoses, and bypass valves for those, to build something that has selectable reactivity. Turn off the bypass and force everything through pilot lock valves, piloted off of the steering input line, and you can steer when you want, but if you're not trying to steer, the lock valves will hold it where it is. Open the bypass valves to put it back to normal. You'd want a fairly low pilot trigger pressure as this system would be somewhat having to fight itself in low-force-needed steering situations, and it'd be interesting to get it dialed in.

Also in theory, you can change the reactivity profile by changing the leaf springs in the steering valve. In reality, those springs aren't available separately, so you'd be doing a lot of trial-n-error to find compatible springs and dial it into something you like.

You're at one of those points where... try it and see.

I agree with what you are saying would work in theory. It also sounds like a real headache to plumb and fine tune unless it was all built into a single manifold with multiple cartridges.

 

[93blackxj]

What you're finding is why I prefer non-reactive steering valves for mostly-crawling applications. They're more interesting to drive at speed, and not flat-tow-friendly, but the yank-from-hands while crawling, just doesn't happen.

In theory, it'd be possible to add pilot lock valves to the cylinder hoses, and bypass valves for those, to build something that has selectable reactivity. Turn off the bypass and force everything through pilot lock valves, piloted off of the steering input line, and you can steer when you want, but if you're not trying to steer, the lock valves will hold it where it is. Open the bypass valves to put it back to normal. You'd want a fairly low pilot trigger pressure as this system would be somewhat having to fight itself in low-force-needed steering situations, and it'd be interesting to get it dialed in.

Also in theory, you can change the reactivity profile by changing the leaf springs in the steering valve. In reality, those springs aren't available separately, so you'd be doing a lot of trial-n-error to find compatible springs and dial it into something you like.

You're at one of those points where... try it and see.

Yeah I know a non load reaction valve would solve it but would like to keep some of the load reaction feel.

Seems like a lot more trouble than it is worth. If you look back at one of the screen shots I first posted it looks like you can order an Eaton orbital with inlet check valves built into it. Which states that it eliminates wheel kick back. Seems like that would be a better option.

 

[Dethmachinefab]

What about a restricted fitting with an adjustable relief valve on both sides of the ram? Tire turns too fast, overpressure opens relief because it can't get back to the steering valve fast enough, dumps this into an accumulator with check valve tee'd back into the ram side steering line. Yea overcomplicated and probably won't work, but that's what I would play with if I still wanted feedback.

 

[ScottRS]

My experience has been that an inlet check helps protect the pump and helps with manual steering when the pump isn't working. I don't think it'll do much for wheel kick with a load-reactive valve, particularly if you're not actively trying to steer against the kick before/during/when the kick comes, but as "try it and see" things go, it's about the least expensive possible thing to try. I'd give it a go.

I was thinking something like a shock flutter stack would be pretty cool, if you could tune it so that max-possible-steering speed was about its flow limit and higher flow than that, shoved it closed and restricted flow to 25% of otherwise-allowed, or something similar, that'd be trick. Basically transparent to normal steering, but kickback that wants to run the wheel faster, gets blocked/slowed.

 

[93blackxj]

My experience has been that an inlet check helps protect the pump and helps with manual steering when the pump isn't working. I don't think it'll do much for wheel kick with a load-reactive valve, particularly if you're not actively trying to steer against the kick before/during/when the kick comes, but as "try it and see" things go, it's about the least expensive possible thing to try. I'd give it a go.

I was thinking something like a shock flutter stack would be pretty cool, if you could tune it so that max-possible-steering speed was about its flow limit and higher flow than that, shoved it closed and restricted flow to 25% of otherwise-allowed, or something similar, that'd be trick. Basically transparent to normal steering, but kickback that wants to run the wheel faster, gets blocked/slowed.

Yeah I have no idea, I was just going off of that description for the inlet check valve option on the eaton order spec page for their steering control units. States that the inlet relief valve option is what limits mamximum pressure drop across the steering unit to protect the steering circuit. It does show in the model code selections that if you choose the inlet check valve it also comes with the manual steering check valve for steering when power is lost. So that goes along with what you are saying. Attached is the link for the spec page I am referring to.


https://www.eaton.com/content/dam/e...ontrol-unit-catalog-e-stcu-cc002-e1-en-us.pdf

That is an interesting thought, I just dont know enough about the operation of an orbital valve so it sounds like I need to tear into one to see if something like you are talking about is possible. The eaton catalog page does talk about the dual displacement capabilities which switches back and forth from one displacement to another with pressure controlled valves depending on manual or powered steering based on input pressure. Maybe this is the valving you are talking about playing around with? Thank you for your input.

 

[Provience]

What about a restricted fitting with an adjustable relief valve on both sides of the ram? Tire turns too fast, overpressure opens relief because it can't get back to the steering valve fast enough, dumps this into an accumulator with check valve tee'd back into the ram side steering line. Yea overcomplicated and probably won't work, but that's what I would play with if I still wanted feedback.

The steering damper linked above does it in the best way by just adding basically a shock inline