Self centering rear steer

[Rockwells607]

I have ran a rockwell rear steer for years , I have an electric over hydro pump and log splitter valve and it has worked fine, I built my wife a new buggy and put these axles in it and decided to go with a second power steering pump so it always has pressure and lightens the load on the charging system ... I build everything myself if possible and always lookin for cheaper or easier Solutions so I don't hafta buy things , only What I need so... Has anyone figured a way out to rig up self centering option as opposed To the awsome PSc or stazworks expensive alternatives ?? Parts from TSC or northern hydraulics that would save money and a do it yourselfer could handle ?

 

[TBItoy]

I doubt you'd find what you need at northern or tac.

You'll have to have an electric solenoid valve, a logic controller, and some sort of sensor system to indicate center and what side of center your steering is.

 

[patooyee]

I've often thought about some sort of spring-loaded switch system where there is no computer involved. Basically the "sensing ram" would have springs on it with stops so that when the rear was turned right a switch was held down that turned it back left, and vice versa. The switch would operate through a 5-pin relay so that when the in-cab switch was pressed it wasn't getting power but when the in-cab switch was let go of power would return to the switch on the axle, returning it to center. The stops on the springs would have to be set up so that center was the only position that neither of the axle switchers were activated and the whole system could get power through an in-cab toggle so that return to center could either be on or off. This system would not require a computer or a "sensor" but would require a solenoid valve. I haven't put a ton of time into figuring out what the axle-side spring mechanism would look like but I'll try to draw something up rough-hand post what I have imagined later.

 

[Beerj]

I have a question that is somewhat related. Has anyone ever set up the rearsteer similar to a pettibone? Essentially running the front and rear with the steering wheel? All I ever see is controlled by a toggle or similar.

 

[patooyee]

I have a question that is somewhat related. Has anyone ever set up the rearsteer similar to a pettibone? Essentially running the front and rear with the steering wheel? All I ever see is controlled by a toggle or similar.

How is it set up on a pettibone?

 

[Beerj]

There's a selector switch to choose between front, rear, 4wsteer (front and rear turn opposite of each other), and crab (front and rear turn the same direction). No return to center but all input is through the steering wheel.

 

[patooyee]

There's a selector switch to choose between front, rear, 4wsteer (front and rear turn opposite of each other), and crab (front and rear turn the same direction). No return to center but all input is through the steering wheel.

Sorry, I meant how do they accomplish it mechanically? Whatever system they have is probably the best way but it may not match up to what we do at all. I know little about them but here's what I do know:

1. Low RPM, high torque engines.
2. Very large cylinders compared to what we use.
3. Relatively small tires compared to us. (Although I know the big ones have huge narrow tires.)
4. Bare minimum comfort / high functionality to keep production costs low. (No one cares to buy a boom lift with leather interior, Bose surround system, etc.)

Based on the above I would venture the following ASSumptions:
1. They do not use 2 pumps as this would conflict with fact #4 in two ways: A, two pumps are more expensive than one. B, metering two separate systems equally is a valving challenge and adds more valves that are expensive and complex.
2. If #1 is correct it means they divide power between both axles all the time. (Just like we would with one pump steering both axles all the time.)
3. The large cylinders are an indicator that I am right on #2.
4. Since the single pump has to fill 2 gigantic cylinders it is probably very high displacement, way above any conventional power steering pump. Its probably a gear pump or some other heavy industrial low-rpm, high displacement unit to match the low rpm, high torque industrial engine.

If correct in the above assumptions, the system is challenging to adapt to what we do because those pumps are only good to very low rpms, like 3000, and our engines spin pumps very fast, like up to 11,000 rpm. Those pumps are also very inefficient in terms of parasitic loss. A gear pump producing 5GPM uses more HP than a vane pump producing 5GPM. Compounded to the displacement levels that I am assuming in #4 above you could be looking at a 50-100hp loss on an engine like ours.

I've never driven one but when one does, if one axle binds, does the other one turn still? Or do they both bind? That would tell me more. But this is a lot of conjecture on my part when someone who knew something about them could tell us for sure.

 

[Rockwells607]

Radio control crawlers have this option, I've heard
Of buggies doing it but the draw back that I know of is that one orbital valve and pump isn't enough to supply both Rams at the same time so it makes them both slow when used together ... If that makes any sense, another idea I've heard is not self centering but a throttle cable or the like hooked up to the knuckle with and indicator on the dash telling you where the wheels are without looking back...

 

[Beerj]

Radio control crawlers have this option, I've heard
Of buggies doing it but the draw back that I know of is that one orbital valve and pump isn't enough to supply both Rams at the same time so it makes them both slow when used together ... If that makes any sense, another idea I've heard is not self centering but a throttle cable or the like hooked up to the knuckle with and indicator on the dash telling you where the wheels are without looking back...

I remember seeing that years ago, back when rearsteer was fairly new. Might have been in jp magazine. You could maybe even hook it up to some lighted arrows for a little more bling factor.

But yeah, I guess you would need 1 huge orbital and a pretty big pump to have 4 wheel steer in the wheel.

 

[Beerj]

Sorry, I meant how do they accomplish it mechanically?

...

I've never driven one but when one does, if one axle binds, does the other one turn still? Or do they both bind? That would tell me more. But this is a lot of conjecture on my part when someone who knew something about them could tell us for sure.

Lots of good points there. I'm fairly certain that the steering is ran off of the main hydraulic pump which also powers the boom etc. I've never had the steering bind, if anything, the whole machine just gets pushed side to side by the wheels. The ones we have at work are all fly by wire so maybe instead of an orbital valve they just have a switch and solenoid that detects input from the steering wheel and controls the steering cylinder accordingly. That being said, maybe it would be possible to incorporate the traditional rear steer toggle that everyone uses, into the steering column.

 

[John Galbreath Jr.]

There's a selector switch to choose between front, rear, 4wsteer (front and rear turn opposite of each other), and crab (front and rear turn the same direction). No return to center but all input is through the steering wheel.

I had that on my Purple Jeep from John at Stazworks. My stuff is still on his site!

http://www.stazworks.com/old_rear_steer.htm

The crab has absolutely no use to us. The circle feature was cool in tight areas trail riding. I did not have enough steering pump to do more than trail ride with that feature on. But, with ARBs front and rear (open) and circle steer, I could put that big thing about anywhere. We used the same setup on the 38 Special out of that old Jeep, but we cut down the harness and deleted those "features" as they were really not practical to hard wheeling.

 

[RustyC]

The Caterpillar Telehandlers have this type steering systems as well. Cat also uses a selector valve to direct oil flow.
Basically the system uses a load sensing pump to supply oil flow as needed. No input from the operator = minimum pump swashplate angle / minimum oil flow.
Operator input causes the pump swashplate to move towards max angle = more oil flow / faster steering. Compensator valve on the pump limits max pressure.
The system uses a steering wheel, orbital valve and lines to the front steering cylinder just like our rigs.
For the rear, oil from the orbital valve is also directed to a selector valve. Here the oil has three options. Depending on toggle switch position.
1 Two wheel front only steering = the oil is blocked by the spool, rear tires do not move.
2 Crap Steer 4 wheel steering = the oil is directed to the rear cylinder ports just like the front, rear tires mimic front.
3 Circle Steer 4 wheel steering= the oil is directed to the opposite rear cylinder ports, rear tires turn the opposite of the front.

 

[paradisepwoffrd]

Re:

I have thought about using an "indicator" and centering manually vs auto. Basically a cable, one end attaches to the ram, so the shaft moves the cable in/out. The other cable end attaches to a slide/dial/gauge on the dash. As the ram moves, it moves the indicator, telling you ram position. You could then steer without looking back

Sent from my SM-N900T using Tapatalk

 

[patooyee]

Here's a really rough sketchup of what I was talking about in my first post:

The center part is the switch pad. The round things are basic button-type switches. The arrow part pointing down would have to be attached to the steering / tie rod and the large upper bracket would be stationary on the axle. On each side is a plunger / paddle with sliding shafts. On each shaft would be a spring. (I didn't feel like modeling up the spring, you'll have to use your imagination there.)

In the picture the tie rod has moved right, pushing the right switch into the sprung plunger / pad and thereby activating the switch. The switch would be wired through the five pin relay so that while you were holding the right switch in the cab nothing would be happening at the switch on the axle other than being depressed. As soon as you let off the switch in the cab power would be applied to the switch at the axle which would be wired to the left side on the solenoid valve, thereby activating the valve and turning the steering left. There would be just enough space between plungers / paddles so that in the center neither switch was depressed. Therefore, the system would stop acting once the switch on the right in this pic stopped being pushed by the sprung plunger/ paddle. It works the same way in both directions. This setup does not require a computer / PLC / logic controller and by mounting the stationary top bracket on a threaded rod on the axle housing with nuts on both sides exact center could be fine-tuned as things bent / settled over time.

 

[Eddyj]

I think it was a flat fender jeep with a cummins that had a nice indicator on the dash right in front of the steering wheel. I think I seen it in a TTC

 

[patooyee]

Don't know how many here actually have rear steer but here are my observations after having it for years now and never wanting to live without it again. I would have it on my daily driver if I could. I'm not claiming to be a rear steer master with the likes of John but maybe the experience I do have is valid. Many of these are along the lines of John's observations:

1. Crab walk is nearly useless. There are only two times I use it other than to show off. One is on my narrow trailer where half of each tire rides off the side of the trailer. If I pull up a little too far to one side crab walk makes it easy to center up by simply backing up a foot or two and then going forward again. The other time is when I am on a narrow trail with very little space in a line and have to move over to allow oncoming traffic to pass. This is very rare, maybe twice since I've owned a rear steer rig.

2. 99.9% of rear steer use is circle-steer.

3. You don't need a dash gauge. Its neat but even at slow speeds your ass tells you if the rear end is wandering even a little. And if a gauge was telling you you are straight and your ass says otherwise, you're going to do what your ass says, not the gauge. You would be amazed at how accurate your ass can be without looking.

4. Almost the entire use of self-center is for when you are throttling or maneuvering quickly and you don't want to worry about manually recentering or looking at a gauge. Its for when you need to make a quick correction and then let it bring itself back to center. In these situations you don't take your eyes off the trail to look at a gauge. Its similar to why we have rev limiters. When you're in it you're not going to break concentration to look down at your tach to make sure you're not over revving the engine. You rely on your limiter to do that for you.

 

[patooyee]

5. I personally would have no use for the rear to follow the front via the steering wheel. You don't always need to steer that sharp and when you did full throttle assaults they would be super-hairy.

 

[fordcontraption01]

I have rear steer with two pumps and am pretty good at driving it and would not have anything else without it either I agree with patooyee. But mine is so long it wouldn't be feasable without rear steer :****:

 

[patooyee]

I have rear steer with two pumps and am pretty good at driving it and would not have anything else without it either I agree with patooyee. But mine is so long it wouldn't be feasable without rear steer :****:

2 pump allows to you truly use the rear at the same time as the front. Then once you get used to it it become muscle memory and its like an extension of your arms or legs or something.

 

[Eddyj]

I have rear steer with two pumps and am pretty good at driving it and would not have anything else without it either I agree with patooyee. But mine is so long it wouldn't be feasable without rear steer :****:

How long are you?