1 Ton Rack and Pinion Steering on a SFA rig...

[Russell]

Never fooled with hydro assist with rams, but I did do some work with power steering gear boxes.
On the ones I worked on, there is a torsion spring that keeps the spool valve centered.
Until the valve moves, there is no pressure applied.
The spring is "between" the input shaft and the output shaft. When you turn the wheel, if the output shaft moves easily, no pressure.
Its when the shaft cannot move easily that the spring twists, the spool valve moves off center, pressure develops and assists the output shaft to move.

As soon as the output shaft realigns with the input, the spool centers again and the assist stops.
If you keep turning the wheel, the output shaft "chases" the input until they are aligned again.

So, if the drag link was disconnected on a standard box, you would never see any pressure.

But, if it was locked so that it could not move, then you would see pressure with no feedback.
The ram would just continue to move as long as you held pressure against the wheel in either direction.

The torsion spring would tend to recenter the wheel when you eased off the turn.

Still say it would be cool to play with.

Actually not as fun as it sounds haha! During KOH our steering box broke and seized up on us. If we applied pressure in either direction the ram would move though. The break allowed the sector shaft to move freely (mostly, locked up a few times too...) but the steering wheel was limited.

The ram moved the steering to lock way too fast and wouldn't center at all. We probably looked totally drunk trying to limp it to the next pit. It was all we could do to keep the truck on the trail

 

[Russell]

Yeah but the A arms droop too no? I dont understand how hooking a front tire on one of these kinda trucks when drooped is any different than on an A arm IFS truck. They both get the camber change on droop.

There is some camber change, but not nearly to the same degree... I saw a ford truck up here catch some air and hook a drooped tire once too. Whipped his tail around in epic fashion, but he landed shiny side up and only had a little whiplash to brag about haha!

I am half considering trying a TTB setup on a 2dr Tahoe

 

[ktmoutfront]

On an a arm setup you can set it to have 0 camber at full droop. So they never tuck under. At ride height it looks a little funny. But it sure does work in the dirt. If you look at the pro 4 trucks in short course, that's the way they are set up.

 

[Fordum]

Actually not as fun as it sounds haha! During KOH our steering box broke and seized up on us. If we applied pressure in either direction the ram would move though. The break allowed the sector shaft to move freely (mostly, locked up a few times too...) but the steering wheel was limited.

The ram moved the steering to lock way too fast and wouldn't center at all. We probably looked totally drunk trying to limp it to the next pit. It was all we could do to keep the truck on the trail

Yep, after I woke up this morning, I realized that the total travel from centered spool to wide open is probably less than 1/16 wheel turn.

The only that it might work, would be to let the sector shaft turn slightly under increasing tension.
Say enough for a full turn lock to lock.

This would let the spool valve open gradually the farther you turn the wheel.

Something like two leaf springs, one for left and one for right, which would also tend to cause the steering wheel to recenter.

 

[Blue85]

Why does a steering box output shaft have to move???

When you turn the wheel, the shaft tries to move. If it can't, the spring gives, which causes the spool valve to shift and applies the hydraulic pressure.

If you have hydro assist, the drag link is resisted and it causes pressure to both the ram and the internals.

What if you removed the drag link and locked the output shaft for off road?

The wheel would not turn beyond a certain point, but the truck would.
It would be like the modern fighter jets. The control stick does not move, but the sensors feel the pressure of the pilot's arm and move the control surfaces accordingly.

It might take some getting use do, but would be way cool to drive........

Then, when you got to the highway, just remove whatever you have attached to the output shaft and reattach the drag link....

This is lunacy. You would have no idea what direction your wheels are pointed in except the feedback of which way the vehicle is tracking. Then when you hit bumps or jump you would inadvertently steer in random directions. All you would do is wander the vehicle around and crash.

 

[miniwally]

I don't have a lot of time here but you guys need to do some research on this, It really doesn't work without a lot of effort.

The way you are doing your drawings you will have "roll steer" (I'm calling it this for this discussion sake but it's a bit different). Meaning that the axle articulates the steer shaft will stay straight but the axle twist will actually make the tires turn, or if the body rolls the tires will turn.

This discussion is nothing new and the info is out there for how to make it work. Steering box goes under the seat basically and the drag link runs parralell with the suspension links and mounts in the sweet spot, for bump steer minimizing.

Jesse Haines KOH rig is like this, Randy Ellis built his jeep like this many years ago, and right now on Pirate dirtfab is building a KOH modified rig with this type of steering.

 

[Fordum]

This is lunacy. You would have no idea what direction your wheels are pointed in except the feedback of which way the vehicle is tracking. Then when you hit bumps or jump you would inadvertently steer in random directions. All you would do is wander the vehicle around and crash.

And what part of all that is at odds with "way cool to drive"??

Never said it might not be tricky, but don't forget this is for offroad, not highway.
I have driven my old Jeep with a full turn of play in the wheel. Makes planning ahead very important.

Friend of mine has a Snapper zero turn riding lawn mower. Instead of two levers, it has one joystick next to the seat.

That thing is a hoot and a half to drive. We took turns running into things and almost getting tossed off until we finally got the hang of it.

As for not knowing where your tires are aimed, although you don't realize it, you don't really know it now.
When you get behind the wheel, and the steering wheel is level, you assume that the wheels are straight.
But they could be cranked all the way over.

And I have maneuvered way too many boats without rudder indicators to let that sort of thing bother me.....

For road stuff, I demand that my brakes and steering be right.
When it comes to heavy off road stuff, brakes are usually optional, and as far as the steering is concerned, as long as it will take suggestions, I'm happy....

 

[big pappa b]

If I was to build another one, it would be custom leaves with tripple bypasses, air bumps and balance front to rear.

I like this idea..just need funds for the triples

 

[Stomis]

I don't have a lot of time here but you guys need to do some research on this, It really doesn't work without a lot of effort.

The way you are doing your drawings you will have "roll steer" (I'm calling it this for this discussion sake but it's a bit different). Meaning that the axle articulates the steer shaft will stay straight but the axle twist will actually make the tires turn, or if the body rolls the tires will turn.

This discussion is nothing new and the info is out there for how to make it work. Steering box goes under the seat basically and the drag link runs parralell with the suspension links and mounts in the sweet spot, for bump steer minimizing.

Jesse Haines KOH rig is like this, Randy Ellis built his jeep like this many years ago, and right now on Pirate dirtfab is building a KOH modified rig with this type of steering.

This whole thread is just spit balling really.