Steering tech

[Busa]

See this on another forum just though i would pass it on.

Quote:
Allright Lance from Keller. I am trying to piece together a cheapo full hydraulic system for the rocks going in my junk. I have a saginaw style pump that I was told is a high volume pump that pushed an AGR box with a Rockram assist ram not very well. I am going to rockwells with a 2"x10" ram that I have already purchased and plan on using the radiator pipe resiviour. I am going to run 44" tsl''s. I guess my question is........ Do you have an orbital on the dent and clearance rack that would give me 3.5 to 4 turns that I would like. I am very green when it comes to full hydro but I do know I like it when I drove Tigger.


The first thing I'd do is trade that 2" cylinder for atleast a 2.5"

All day long I have this same conversation, and I know all of everyone's buddy's are using this set up and they work great. I hear it 100 times a day, from guys who have this set up and it sucks. "I have plenty of power, it works great, it wont turn left, but it's great"

This is not a sales pitch, I help guys all the time with ag cylinders, this is just the facts

The power of a cylinder is the pistons surface area x the pressure of the pump. area= 3.14(pie) x radius squared.
2/2=1 R=1, 3.14X1X1 =3.14 3.14x 1500psi +4710

So the power on the cylinder (just the piston end) is 4710. It can exert 4710lb which seams like alot but when you consider the scrub (amount the tire travels out side the fulcrum of the knuckle) which is longer than the length of the lever on the knuckle (steering arm) that number starts to reduce significantly.

Oh well you might say.

But heres the crapper, the retract power on the cylinder is the piston surface area MINUS the rod, so in your cylinder on the turn side that pushes the rod in, you have a 1/4 inch of piston leaving you with 3.14 x1 x1 =3.14 (area of the piston) minus 3.14 x .75 x.75 = 1.76625 which equals 1.37375 when multiplied times the pump pressure (1500psi for this experiment, but just so every one knows, stock pumps are usually closer to 1000psi) gives you a whopin 2060 lb of turning force. Just an fyi, thats less that even a crappy steering gear.

They make 2" bore cylinders with smaller rods than 1.5, but then the strength of the rod comes into play. Ag cylinders are pretty much made to just be used in one direction, so the mfg arn't concerned with the retract power of the cylinder.

When the pressure in the system gets beyond the force of the cylinder (your trying to turn to the weak side of the cylinder and it needs more than it can exert, which is alot when that half of your truck allready weighs more than the cylinder can produce) the pump shuts off in an attempt to save its self, the valve just locks down. No fluid in, which means your doing all the work with the orbital (its a little pump too that you provide the power to with your arms) this happens for more than about 2 seconds on a high volume pump and its empty, nothing to lubricate, nothing to get rid of heat, so that happens a few times or for a long time once, and the pumps gone.

Im sure this isn't what you want to hear since you allready have all this stuff. Run a standard volume pump if you have to run a small cylinder, they will live longer, but a properly sized cylinder will provide better performance.

Now if anyone is still awake, I can get you an orbital that will provide you with that ratio of steering, reguardless of what cylinder you have. Im assuming you have a single ended cylinder, any orb you get is going to give you about 1 more turn one direction that it does the other. With the cylinder you have now your lookin for a valve in the 7.6ci range. It will be about 3 turns one way and 4 the other.

LG