Rear steer hydraulics?

[DirtyComanche]

Outta the blue on this one... But I was looking at a total pile of a suzuki that has rear steer. And I started to think. Which is bad. Normally I'd go read pirate until I get bored with the concept, but instead I posted here.

 

 

So, can you get a simple hydraulic valve that would allow you to cycle an actuator in and out, yet offer some sort of automatic return to centre?

 

Do you think P/S pump output would be able to drive a second ram? I don't see any reason why not, since I would only use rear steer when I'm moving slow, and fast steering isn't a huge deal. And it drives the ram I have without any hiccups what-so-ever.

 

Comments?

 

Maybe I should go read pirate until I realize this is immensly complicated and lose interest.

[rockhardzj]

Outta the blue on this one... But I was looking at a total pile of a suzuki that has rear steer. And I started to think. Which is bad. Normally I'd go read pirate until I get bored with the concept, but instead I posted here.

 

 

So, can you get a simple hydraulic valve that would allow you to cycle an actuator in and out, yet offer some sort of automatic return to centre?

 

Do you think P/S pump output would be able to drive a second ram? I don't see any reason why not, since I would only use rear steer when I'm moving slow, and fast steering isn't a huge deal. And it drives the ram I have without any hiccups what-so-ever.

 

Comments?

 

Maybe I should go read pirate until I realize this is immensly complicated and lose interest.

Oh, how much fun that would be.

 

For one, many people are lost as to how to use rear steer to their advantage. Believe me, I've hopped in a rig, and level ground was difficult to navigate. Its a whole new level of feeling stupid.

 

As for return to center, Check out the rear steer system on a newer Chevy/GMC with the quadra-steer or whatever they called it. I beleive there is a super heavy duty spring which the system has to fight to steer it, but once the flow stops, the spring pushes the ram back to center.

 

I also beleive that the GM style rear steer concept used an electronically driven pump, and not engine powered. Something to do with too far for the fluid to travel, and the hoses would expand too much, loosing efficiency.

 

At any rate, I'll check for a few pics around the net for ya and post em up, so you can get a better idea.

[Pete M]

All I can really add is that I read once that a guy added a bar to his rear steer that locked it in the no-steer position. I think it was for competition use (for events where steering isn't allowed) but I would definitely consider a mod like that if the rig ever saw pavement or speeds above 15mph for safety reasons. My 2cents. :D

[DirtyComanche]

I looked at a quadra-steer truck quickly a couple times. It looekd like a compromised setup to me, after all it was built for a street-driven truck. They used a double ended ram, IIRC. I don't have money like that.

 

You'd think that hose explansion would be minimal. It is quite a distance. But, hydraulic hose is tough stuff. Especially if it's rated for 4000psi and my pump tops out at about 1400psi. One way or another I doubt it would be an issue as I do not forsee using it at any speed. The truck drives WEIRD enough as it is. Probably something to do with zero caster and leaf springs.

 

 

A lock-out would be a novel concept. But I know I'd just leave it unlocked anyways. If I crab walk it at 100, I'll just have to put some faith in the exo cage.

[rockhardzj]

http://www.pickuptruck.com/html/stories ... hree1.html

 

It should give some insight.

[JeepcoMJ]

umm...so why can't you just put the outer ends of a front axle onto a rear axle (matched diameters), then put the front hubs on, have custom shafts made or find a set that would work, put hubs on it for 4wd or lock rear axle permanently, and then set up the steering components with a similar to stock steering box? i know you can't run a shaft to the steering box, but seems to me that you could set it up with a little 1 horse electric motor to turn it, or bigger of course if needed, and then you wouldn't have to worry about the power steering...if the motor were strong enough that is...

[DirtyComanche]

That's how you build the axle, but no electric motor would give enough force to push the knuckles to steer.

 

 

You need hydraulic force. A single ram on the tie-rod works.

 

 

Wait, I see what you mean. Use the motor to turn the steering box. Would be interesting but highly complicated. I'd be better off buying an orbital valve than doing that.

[JeepcoMJ]

That's how you build the axle, but no electric motor would give enough force to push the knuckles to steer.

 

 

You need hydraulic force. A single ram on the tie-rod works.

 

 

Wait, I see what you mean. Use the motor to turn the steering box. Would be interesting but highly complicated. I'd be better off buying an orbital valve than doing that.

 

exactly.

 

actually, not complicated at all. it would just need a regulator and a flow control type thing. flow one way a certain amount, a basic computer chip controls turning and how far that way, and vice-versa. at a no-flow rate, you could have the basic chip designed to re-center the motor/axle based on a sort of sensor that has to line up with it's counterpart...a.k.a. if it's not "lined up" the "computer" tells it the motor to "re-adjust" until the sensors get a clear reading of each other.

 

actually, burnout rate on the motor would be minimal too...because it only needs to apply the pressure to turn once for starters. after that, it only applies to turn if the axle starts to move...you'd turn the dial to say, a 9 o'clock position to turn that 90 degrees left. leave the dial there. computer compensates by controlling the motor and saying "ok, you're turned that far now, you can stop turning...."

 

I think it's an idea worth looking into...and I suppose IF you made it hydraulic assist steering (power steering) box, the turning would be very simple and you'd have an extemely reliable system.

[DirtyComanche]

That's way over complicated. You'd need to run a drag link and a panhard bar for that to work. Unless you were using leaf springs. And you'd still need to run hydraulic hoses all the way to the second box. And a control setup for a motor. And a motor.

 

 

The correct valve is a shuttle valve. 1 pressure in line, 1 return, 2 outputs for each side of the ram.

 

 

Which I new before I asked. But totally had forgotten about. Been a long time since I took any hydraulic theory.

[rockhardzj]

actually, burnout rate on the motor would be minimal too...because it only needs to apply the pressure to turn once for starters. after that, it only applies to turn if the axle starts to move...you'd turn the dial to say, a 9 o'clock position to turn that 90 degrees left. leave the dial there. computer compensates by controlling the motor and saying "ok, you're turned that far now, you can stop turning...."

 

I think it's an idea worth looking into...and I suppose IF you made it hydraulic assist steering (power steering) box, the turning would be very simple and you'd have an extemely reliable system.

Or, you can just have it as a low speed motor, attached to the power steering box by a belt and pulley system. The motor can essentially turn it as far as it needs to, and wouldn't actually over steer, as the belt is allowed to slip. If you catch my drift. They use the system in 1:1 scare R/C cars out in the desert, few cheap servos to contol the throttle, an actuator to hit the brake, and an actuater for the gear selector, in an automatic, of course, with all the teeth knocked out so it can freely shift between gears and into reverse.

 

Speaking of 1:1 r/c, anybody got a junk ford escort or something that won't pass inspection that you want to have some fun with out in the desert sometime? :D I'd do a long range system, complete with centrally mounted video camera with a remote signal that can turn 360*...