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Nordic1
07-04-2005, 02:52 PM
So I am looking at 1.5"x8" rams on surplus center's website

http://www.surpluscenter.com/

And I see two 1.5x8 rams...

one with a .750 "rod"

http://www.surpluscenter.com/item.asp?UID=2005070413442005&item=9-4410-08&catname=hydraulic

And the other with a 1.000" "rod"

http://www.surpluscenter.com/item.asp?UID=2005070413442005&item=9-6645&catname=hydraulic

The wierd thing is the 1" (0.250 larger than the other) rod is rated at almost double "push/pull" power. My understanding was that the more fluid in the ram, the more power it would have... Does this make sence to anybody?

-Chase

Kraqa
07-04-2005, 03:40 PM
the power of the ram will be determind by the amount of volume acting on the surface area of the bore. The rod size should only affect the amount of force you can push/pull not the actual force the ram will creat.

i'l be that those rams are just difrent construction, making one be able to handle more power.

but if your doing assit you want a ram that will be able to push/pull relativly the same. these once push alot but have almost half the amount of pulling force. Look into a better quality ram that is closer to equal for each direction. Forklift or bobcat rams are almost equal, also the ones that have the 4 rods that hold them together usually are aswell.

Ken L
07-05-2005, 12:28 PM
A little physics:

Force=pressure X area

The area of the the rod side of piston in the cylinder with the 1" diameter rod is smaller than the area with the .75" diameter rod.

That means that the cylinder with the 1" rod will give you less force when turning the direction that the rod is retracting. However, it will give you more speed going in that direction.

Force numbers: I don't know exactly what a PS system runs at, let's say 1000 psi. I've got charts that show 1.5" bore cylinders with 1" rods and with 5/8" rods, but if you're interested I can post the calculations to do the .75" rod, but this example should work for illustration. On the non-rod side of the cylinder, at 1000psi, the force generated is 1,767 pounds. On the rod side of the 1" rod, it's 982 pounds, on the .625 rod it's 1460 pounds.

Speed numbers: Again, I'll assume that a PS system flows 2 GPM. On the non-rod side of the cylinder, the speed is 261 inches per minute. On the 1" rod cylinder, it's 471 IPM, the .625" rod is 316 IPM.

I have a chart somewhere that shows the strength of each rod diameter, but I can't find it right now. Just wanted to post a little info to think about in making your decision.

Kraqa
07-05-2005, 06:10 PM
yes that makes ense. but still doesn't address the issue of having a ram that more faster a less powerfull in one direction. not what you want for a stearing system.

Nordic1
07-05-2005, 06:42 PM
yes that makes ense. but still doesn't address the issue of having a ram that more faster a less powerfull in one direction. not what you want for a stearing system.

Shot PSC an e-mail.... All double acting rams are like that due to the rod.

Ken L
07-05-2005, 09:24 PM
There are ways to get around it; in an industrial hydraulic circuit you can use a flow control to meter out the oil when you "push" on the rod side, thus trying to even out the speed between the rod side and the non-rod side. This doesn't do anything for the force issue, though.

In my mind, the best solution would be to use a double rod cylinder. I saw something like that in a magazine a while ago but I don't know if that was a hydraulic assist or a full hydraulic steering set up. Mounting it then becomes more of an issue as you have to mount the cylinder by the body to the axle and attach 2 rods to the steering.

Kraqa
07-05-2005, 09:34 PM
i'v have never seena double ended ram used in a hydro assyst setup. the pricipal of hydro assyst in my eye's woudl make a double ended ram sorta over kill and way har to mount. in order for the stearing box to power the ram you need the resistance of the pitman arm and drag link. It woudl be cool to see someone use a drag link onto on side then a double ended ram as a tei rod. i don't knwo if it is possible but it woudl be cheeper then full hydro.

the bobcat ram i have has a smaller inlet on the oppositte side to the ram. i'm plannign on tapping one port of the box for 1/4" and the other for 3/8"

to match the ram. its specs on the stroke and power (which i don't have and i'm going off memory) were very close to each other

Ken L
07-05-2005, 10:09 PM
Yea, a double rod cylinder isn't the most practical for a hydro assist, the more I think about it.

ALWJ
07-06-2005, 09:11 PM
I have the 1" rod one and It's not the best. I designed my mounts to handle a bearing stress of 6000 lbs with no safety factor, mounted them perfectly straight with no binding it still manages to wallow out the holes. I'd go with something that has heims on it. I've been looking into replacing mine with the rock logic ram.

chadjans
07-07-2005, 12:37 AM
I have the 1" rod one and It's not the best. I designed my mounts to handle a bearing stress of 6000 lbs with no safety factor, mounted them perfectly straight with no binding it still manages to wallow out the holes. I'd go with something that has heims on it. I've been looking into replacing mine with the rock logic ram.

This is the same thing I am seeing on some setups here in my area. The more I think about it a articlulating end is required on a ram in an assist setup. Because you are taking some of the slop of the steering ends with the ram.

Chad

robselina
07-07-2005, 10:34 AM
I have the 1" rod one and It's not the best. I designed my mounts to handle a bearing stress of 6000 lbs with no safety factor, mounted them perfectly straight with no binding it still manages to wallow out the holes. I'd go with something that has heims on it. I've been looking into replacing mine with the rock logic ram.

Ditto that. When i did hydro-assist on the waggy I used a Lion 2500 2x8 from northerntool.com. Thing has a sloppy mounting system but works. Anyway, when I did full hydro on the scout I opted for a PSC ram with heims and they're certainly not cheap but it's a much tighter and cleaner install....