Home Brew Steering [Archive] - AUSJEEPOFFROAD.COM Jeep News Australia and New Zealand

PDA

View Full Version : Home Brew Steering


Jimmyb
08-08-2005, 06:58 PM
Read first.....

http://www.pirate4x4.com/tech/billavista/PR-Hydro_Steering/index2.html

Have Orbital Valve and Ram..........have 351 Cleveland to drive the Pump, so thinking power steering pump.............and then..........

zzzz
08-08-2005, 07:30 PM
Mate - I hope that ram is going to work out for you.
Where did you get the orbital valve?

Quote - "Enterprising 'wheelers initially began by adapting agricultural and industrial hydrostatic steering systems to recreational 4x4s. However, due to the nature of hydrostatic steering, this approach can have wildly varying results, depending on the match between the steering system being cannibalized or emulated, and the desired performance of the 4x4 in question."

Drop Shane a line if you want to chat about his setup.
He might run into some similar issues or have some good tips.

cheers

z

Jimmyb
08-08-2005, 08:32 PM
The differance with Shanes is that it was an imported kit, this thing I am trying to understand and build is a budget system to try and get to work. Have spoken to lots of people, and yeah can get off the shelf kits from min of $2500 (which I dont have spare) but wheres the fun in that, wanna try and learn and develop. Not everyone has mega bucks, and getting back to my inital plans of this rig, its a budget build.

ps. no disrespect intended towards shane on the cash expenses.

zzzz
08-08-2005, 09:25 PM
The differance with Shanes is that it was an imported kit, this thing I am trying to understand and build is a budget system to try and get to work. Have spoken to lots of people, and yeah can get off the shelf kits from min of $2500 (which I dont have spare) but wheres the fun in that, wanna try and learn and develop. Not everyone has mega bucks, and getting back to my inital plans of this rig, its a budget build.

ps. no disrespect intended towards shane on the cash expenses.

I fully understand what you are trying to accomplish and think it is cool that you are building to a budget.

The reason I told you to drop Shane a line is so that he can share the knowledge has has gained through installing the full hydro on his jeep.
Even though he bought a "kit" from ABT/USA there was still a lot of custom stuff to to get it working, and even now he is redoing some of it to incorporate a big fluid cooler and shorten up the lines.
It has not been a simple bolt in job at all.

Just thought he would have some valuable info thats all.

cheers

z

wendle
09-08-2005, 09:25 AM
i have built a couple of systems using the forklift/ag gear, it is pretty easy, but there is a couple of things to watch out for. first thing is to make sure your orbital is open centre. easiest way to do this is hook all your lines up, leave the low pressure return line sitting in the top of the resivoir, fire the motor up with the steering sitting idle, and make sure there is fluid running back out the return line. a closed centre valve won't do this, and will destroy your pump straight away. the next thing is to make sure the valve is not load reactive. load reactive valving works very well with a double ended, balanced ram, but it will not work with your single ended ram, and will eventually destroy the valve.
you also want to make your low pressure return line as big as possible. i think my last setup was 9/16" pressure lines and 3/4" return line.
if your motor has the big ford teardrop style pump with the built in resivoir you are laughing, you get a big res (you need this with a single ended ram as the fluid level needs to rise and fall with the ram action) and the res is built onto the pump, so you don't need another short line between res and pump. they also have a vented cap, so you can get rid of the relief valve in your drawing, but you really should look at sealing the cap and running a vent hose off it. that shit gets messy when you are upside-down.

FireTruck
09-08-2005, 09:48 AM
Hey Jimmy,

I can't say that I have a huge amount of experience with setting up hydro systems, but I did do my research and chose the kit that would give me the most complete system, at a good price, and with proven performance. I also had a hydro assist system to sell to offset the cost, and the POS kit comes with heim joints and clevis ends so it is very complete. With the double ended cylinder you don't need a tie rod, so that saved some $$ as well.

When I did the math, I found that for me it was cheaper to go full hydro through POS and Sean at ABT rather than re-working my hydro assist system...

That's why I went with the double ended cylinder POS setup through Sean at ABT... this is the same system as Bill is talking about in the link that you have above.

Here's a few things I have picked up - and take note of Wendle's too. The vacuum line from the reservoir to the pump should be as short as possible, and at least -10 rated. In general I have seen recomendations of no longer than 16" in places, and no longer than a couple of feet in places, and no longer than a foot in places... basically as short as possible, and keep the vented reservoir as high as possible.

Mounting the control valve with the ports facing up is also important.

And make sure you factor hydro lines into your build up budget, because they aint cheap and you need to go for quality crimped fittings on quality lines if you want reliability.

I am also adding a cooler to my system - recommended by POS, but haven't got it in yet. Cummins were kind enough to donate me a brand spankin oil cooler (heat exchanger) with 1/2" lines (tube and fin style) and 1/2" fittings... the fittings should be 1/2" or -8 otherwise the pressure drop across the cooler will be too large, and you can actually heat the fluid rather than cool it. If the line between the reservoir and the pump is too long the back pressure can cause cavitation in the pump and aerate the fluid (trust me on this one). Running without a cooler can cause the same thing as the vapour pressure of the hot fluid rises.

And finally, the pump, control valve, and cylinder are matched to give you your desired performance. This depends on the type of cylinder, flow of the pump, and the control valve. I asked for about 3 turns lock to lock, and that's what I got.

I'm sure there's more, but that's what I can think of off the top of my head.

Good luck with whatever you decide to go with.

S.

Jimmyb
09-08-2005, 10:14 AM
Thanks guys, some good feedback there. I guess my other motivation behind building the system up is to learn more and understand what does what a bit better. Its funny how a off the shelf kits seems to leave a bit to be desired in terms of coolers etc. Seems it is more a starter kit in some respects? Will be getting Enzed to cruise up and plumb it all in for me when the time comes.

Have the tie rod section sussed, and think we have worked out how the spear will be mounted, the tie rod will be going up, ie doing a high steer conversion on the existing setup but will use joints at the end.

Will be rewarding once its all working, but I can only see from what I am reading that getting it all working is part a, part b is getting it to run right :)

FireTruck
09-08-2005, 10:25 AM
...the other thing that I didn't mention was that with a single ended cylinder, you get more turning force in one direction than you do in the other - due to the displacement of the shaft on one side.

With a single ended cylinder I am not sure how it would behave in regards to return to centre either... not that it should matter much for a rockcrawler, but with the POS system it returns to centre when driving just like any other regular steering setup.

S.

Wooders
09-08-2005, 12:51 PM
Hey Shane is the Firetruck headed to Unrego'ed territory with full Hydro steer?
My engineer wouldn't have a bar of it unless we were talking tractor rego. (although he will allow rear with a mechanical lockout).

FireTruck
09-08-2005, 01:01 PM
It's still rego'd, but I never (ever) drive it on the road (ever)... and probably never will.

You live in NSW.

S.

wendle
09-08-2005, 01:13 PM
...the other thing that I didn't mention was that with a single ended cylinder, you get more turning force in one direction than you do in the other - due to the displacement of the shaft on one side.

With a single ended cylinder I am not sure how it would behave in regards to return to centre either... not that it should matter much for a rockcrawler, but with the POS system it returns to centre when driving just like any other regular steering setup.

S.

the difference in force left/right isn't noticable. it is a c_ntload of force both ways, so you don't really pick it up. especially considering that force is always different one way to the other depending on sidehill or where the tyres are jammed up against, etc..

return to centre is based around a load reactive orbital, which doesn't work with a single ended ram due to the fluid unbalance in the system. for a straight out rockcrawler it is arguably better to have no return to centre, as you can point the wheels somewhere and forget about them while you concentrate on other things. that's more about personal preference and driving style though..

one thing i forgot to say before is you should limit the travel of your ram to suit your steering throw, standard steering stops don;t last long when the ram is trying to push the knuckles off the housing. tie-rods and rod ends don't cop it well either no matter how beef you make them.

wendle
09-08-2005, 01:15 PM
The vacuum line from the reservoir to the pump should be as short as possible, and at least -10 rated. In general I have seen recomendations of no longer than 16" in places, and no longer than a couple of feet in places, and no longer than a foot in places... basically as short as possible

this is where the factory type pumps with built in resivoirs shine. half your cavitation and lock problems disappear when you get rid of that particular hose.

Jimmyb
09-08-2005, 01:42 PM
I am unsure how the setup works for setting the lock to lock and also the travel of the ram? I that based on the orb?

zzzz
09-08-2005, 01:47 PM
I am unsure how the setup works for setting the lock to lock and also the travel of the ram? I that based on the orb?

I am not sure the valve has anything to do with it...

I believe the travel of the ram is directly related to the size and stroke of the ram, and also where you position it on the diff housing.
Measure carefully for the brackets :D

wendle
09-08-2005, 01:56 PM
I am unsure how the setup works for setting the lock to lock and also the travel of the ram? I that based on the orb?

nah, the orbital will keep extending the ram as long as there is more ram to extend.

the easiest way to do it with an ag type clevis ended ram (if you can physically fit it in the right position) is to mount the ram so that at full extension you are a millimetre or so of one steering stop. then steer the axle so you are a millimetre off the other stop, measure the exposed amount of shaft left, machine a spacer out of delrin or uhmwe (old body lift block), unscrew the clevis off the shaft slide the spacer on, then screw the clevis back on. you now have exactly the right amount of shaft throw.

if you don't have that much room, you can mount the ram so that at full compression you are a hair off one steering stop, then weld a nice big lug onto the axle housing to stop the ram mount on the tie rod at the right amount of extension.

obviously the best way is to have a ram that is already the exact throw you need, but you already have a ram, so either of those methods will work for taking the load off the rest of the system.

the setup on my first buggy wasn't limited, and that in conjunction with the ram being about 15mm off parallel with the tie-rod used to fatigue and stress a lot of stuff.

FireTruck
09-08-2005, 02:02 PM
the way I did it was when I git my high steer arms they were un-drilled... and we drilled the holes in the steering arm so that the steering left to right was where I wanted it, and the ram hit the end of it's travel in both directions at the same point.

If you hit your steering stops before your ram is fully extended, it can rip your knuckles off let alone your steering stops...

And return to centre doesn't mean that when you take your hands off the wheel it goes back to centre... it means that it is just like regular power steering. If you are moving at speed and you take your hands off in the middle of a turn it will return to centre as long as your wheel alignment (and castor) is OK.

If you turn when stationary and take your hands off it will stay wherever it is pointed.

My cylinder is an 8" travel jobby - that is the most common length used.

S.

Jimmyb
09-08-2005, 02:03 PM
That brings another question Wendle, does the ram need to be parallel to the tie rod? I have heard that it does to prevent stress on components.

wendle
09-08-2005, 02:14 PM
That brings another question Wendle, does the ram need to be parallel to the tie rod? I have heard that it does to prevent stress on components.

yep. as close as you can get it. in the horizontal plane it will never be perfect as the tie-rod moves closer and further form the axle housing as the steering cycles, i split the difference when i mounted up my new one. in the vertical plane there is no reason it can't be spot on.

wendle
09-08-2005, 02:19 PM
My cylinder is an 8" travel jobby - that is the most common length used.

you must have some awesome steering lock. i am only using 8" of ram on a unimog axle.


do you get any reactive steering if you say force one tyre at half steering lock into a vertical ledge while the other front tyre is cruising on easy ground?

FireTruck
09-08-2005, 02:25 PM
The steering lock depends on how far out on the steering arm you drill the hole (or how far out the hole is you are using)... I got my steering arms un-drilled and put the holes where I wanted it.

I was going to go for a 7" stroke and drill the holes closer in, but Sean (station on POR) talked me into going for 8" as that is what most people are using and it would give me better force with the arms drilled out further.

You do get some 'feel' if one or both of the tires is under stress trying to turn them one way or the other... same as any power steering setup... but the 'feel' you get is very subtle (unlike most regular power steering setups).

It kinda helps to feel the terrain that you can't see, but the hydraulic force is waaaaay more than any outside force trying to overcome it!

S.

FireTruck
09-08-2005, 02:27 PM
oh, and you can steer the system while the engine and/or pump are not running... this is because the steering valve acts like a little pump. It is hard work, but you can still steer. Pretty similar to when the engine is off for regular power steering.