Orbital Specs/Cross Reference?

[Caver Dave]

Was given an orbital from a Clark forklift and the only numbers on it (paint stenciled) are "2778168" and oddly has 5 ports...
Found a couple references that it was used in the GP-127 (and similar) models, but can find ZERO info on flow, plumbing, etc.

Was hoping someone here (@Blkvoodoo ?) might have some knowledge not found on the interwebs?

 

[Bebop]

Given the chamber size I'm gonna bet it's a 80/100cc, not a big unit.

The 5th port "should" be a port beyond port that you can cap off if you don't use.

Can you get a picture from the back of it ? Usually infos are here :

 

[Scottal]

Only thing about blocking off the 5th port is that its 50/50 shot whether the orbital will still work right. Ive had friends in the past try the 5 ports because they were cheap or got them free and most had zero success with them working properly. Hope you have good luck outta yours though. If not, and you dont want to pay PSC prices, rockwell offroad has a huge selection for about 1/3 the cost over psc. Same orbital Busted Knuckle sells also so high chance of having free beers thrown at you at the top of each trail with those kind of parts!!

 

[Caver Dave]

Thanks for the tag @Bebop
Of course the tag would be on the side facing the frame ... anyways it's a Char-Lynn 243 4007 001 which a LOT more help than the previous number...

The specs to me appear it'll be OK (not stellar) for a single ended ram? And not sure about the "load sensing" junk... was told to run it back into the return side?

3.2 cubic inch

Load Sensing

Non Load Reaction

9/16” UNO ports

7/16” Load sense port

 

[Bebop]

Sooooo, if it's a load sense, you can forget about it, it won't work. Needs a complete load sensing hydraulic system for that.

Load Reactive means that it will return to center. Non Load Reactive means that it won't. Basically 0 feedback in the wheel.

More info:

Orbital Valves - Orbital Valve Information - Hydraulic Steering Unlimited

hydraulicsteeringunlimited.com

Basically it's no good for you because it's load sensing.

Also, 3.2cu is tiny. With a classic PSC 2.5x8 ram, you'd get 7.8 turns of the wheel from lock to lock. Terrible.

Find something else

 

[Chris_Keziah]

Beyond Precise is who I've gotten the last 4 orbitals through and been very happy with them. Think they run $265ish

 

[Bebop]

Only thing about blocking off the 5th port is that its 50/50 shot whether the orbital will still work right. Ive had friends in the past try the 5 ports because they were cheap or got them free and most had zero success with them working properly.

You're right.
After looking at some stuff on the WWW, it seems like there are different configurations of 5th ports. Some of 5 ports orbitals need both T and PB ports ran back to the resi and some need it capped.

If it's a non-load sensing, there is usually a way to make a 5 port work.

 

[Caver Dave]

Also, 3.2cu is tiny. With a classic PSC 2.5x8 ram, you'd get 7.8 turns of the wheel from lock to lock. Terrible.

Find something else

Since I'm pretty much committed to full hydraulic given current tire size/frame limitations
I've got a P-pump w/ usual WTO mods (may have to get the PSC housing/reservoir for more capacity?), Surplus Center 2"x8" single-ended RAM, and 10"x12" stacked plate cooler...

What would be your recommendation for orbital displacement?

Beyond Precise is who I've gotten the last 4 orbitals through and been very happy with them. Think they run $265ish

What brand(s) are they peddling/have you received?

 

[Bebop]

Since I'm pretty much committed to full hydraulic given current tire size/frame limitations
I've got a P-pump w/ usual WTO mods (may have to get the PSC housing/reservoir for more capacity?), Surplus Center 2"x8" single-ended RAM, and 10"x12" stacked plate cooler...

What would be your recommendation for orbital displacement?

What size shaft would this ram use ? I'm not super familiar with the Surplus center stuff.
For orbital size, what is your intended use ? Any road driving ? Trailer queen?

 

[Caver Dave]

What size shaft would this ram use ? I'm not super familiar with the Surplus center stuff.
For orbital size, what is your intended use ? Any road driving ? Trailer queen?

RAM Specs:
Double Acting
Bore x Stroke 2" x 8"
Barrel Thickness 0.25"
Gland Retainer Threaded in gland
Pressure 3000 PSI max.
Rod Dia. 1.25"
Column Load 3000 PSI max. @ full extension
Ports SAE 8
Retracted Length 15.5"

97% offroad (trailered), 3% on road <100 miles/year (tagged/insured)

 

[Bebop]

2" ram is pretty small. Not gonna make a ton of power.

But, the math is as follows :

Lock to lock volume : 15.28cu or 250.4cc
Classic orbital valves are 100cc, 120cc 160cc, 185cc, 200cc

Anything over 160cc the pump won't keep up with.

Since the ram isn't really big, 100cc ends up with 2.5 turns lock to lock.
120cc = 2.1 turns
160cc = 1.56 turns

I'd advise a 100cc to keep the steering manageable on the road.

Edit : a 80cc orbital would give you 3.1 turns. Totally doable and would keep the pump super happy too.


Ideally you'd want to move to a 2.5 ram for more force. They usually come with a 1.5" rod.

This would give you a 25cu chamber volume, or 410.4cc

100cc ends up with 4.1 turns lock to lock (too slow IMO).
120cc = 3.4 turns
160cc = 2.56 turns

120cc would be my advice because of the street driving.

I personally like the faster steering and a 160cc orbital would be my choice, but it can become harder to control at speed.



Hope this helps !

 

[paradisePWoffrd]

2" ram is pretty small. Not gonna make a ton of power.

But, the math is as follows :

Lock to lock volume : 15.28cu or 250.4cc
Classic orbital valves are 100cc, 120cc 160cc, 185cc, 200cc

Anything over 160cc the pump won't keep up with.

Since the ram isn't really big, 100cc ends up with 2.5 turns lock to lock.
120cc = 2.1 turns
160cc = 1.56 turns

I'd advise a 100cc to keep the steering manageable on the road.

Edit : a 80cc orbital would give you 3.1 turns. Totally doable and would keep the pump super happy too.


Ideally you'd want to move to a 2.5 ram for more force. They usually come with a 1.5" rod.

This would give you a 25cu chamber volume, or 410.4cc

100cc ends up with 4.1 turns lock to lock (too slow IMO).
120cc = 3.4 turns
160cc = 2.56 turns

120cc would be my advice because of the street driving.

I personally like the faster steering and a 160cc orbital would be my choice, but it can become harder to control at speed.



Hope this helps !

Also to note. With a single ended ram, the cylinder volume in one direction is more than the other. So it will turn faster in one direction vs the other. In the 2.5" ram example, it would be ~150% faster one way vs the other.

 

[Bebop]

Say no to single ended rams !

 

[Chris_Keziah]

Since I'm pretty much committed to full hydraulic given current tire size/frame limitations
I've got a P-pump w/ usual WTO mods (may have to get the PSC housing/reservoir for more capacity?), Surplus Center 2"x8" single-ended RAM, and 10"x12" stacked plate cooler...

What would be your recommendation for orbital displacement?

What brand(s) are they peddling/have you received?

You'll either need to do the resi mod to gain some capacity or do the psc back half and run an external resi. More fluid volume you can get the better.

Unless you've already bought the surplus center ram I'd recommend something else. The trail gear 2.25x8 is what I've used in the past with a 7.3cuin orbital. Should be right around ~3 turns lock to lock. The issue with the surplus center rams is that they run a stupid large shaft (there's a recent thread on here where it's talked about).

Not sure what brand they are, pretty sure they're nameless. I'd be willing to bet it's the same as TG and Rockwell offroad.

 

[Caver Dave]

120cc would be my advice because of the street driving.

Hope this helps !

120cc aligns with Chris' 7.63ci recommendation below

Also to note. With a single ended ram, the cylinder volume in one direction is more than the other. So it will turn faster in one direction vs the other. In the 2.5" ram example, it would be ~150% faster one way vs the other.

Yeap, knew that going in... aside from the most OCD/anal folk, most say they stopped noticing it after the 1st 5 minutes?

You'll either need to do the resi mod to gain some capacity or do the psc back half and run an external resi. More fluid volume you can get the better.

Unless you've already bought the surplus center ram I'd recommend something else. The trail gear 2.25x8 is what I've used in the past with a 7.3cuin orbital. Should be right around ~3 turns lock to lock. The issue with the surplus center rams is that they run a stupid large shaft (there's a recent thread on here where it's talked about).

Not sure what brand they are, pretty sure they're nameless. I'd be willing to bet it's the same as TG and Rockwell offroad.

Honestly, was going to see how the stock "canned ham" res worked... lot's of folks say it'll work fine (maybe with extending the neck?) and go from there.
Unfortunately, already have the SC ram sitting here but not opposed to starting over if the difference between 2" and 2.250"/2.5" will be that noticeable?

 

[Bebop]

Yeap, knew that going in... aside from the most OCD/anal folk, most say they stopped noticing it after the 1st 5 minutes?

Street driving it will be VERY noticeable. I don't recommend it.

Honestly, was going to see how the stock "canned ham" res worked... lot's of folks say it'll work fine (maybe with extending the neck?) and go from there.

Agreed, seen the stock resi with extended neck (using nothing more than a piece of radiator hose) work great.

Unfortunately, already have the SC ram sitting here but not opposed to starting over if the difference between 2" and 2.250"/2.5" will be that noticeable?

2" ram with a 1.25" rod at 1300 PSI (modded P-Pump) will make about 2500 pounds of force.
2.5" ram with a 1.5" rod at 1300 PSI will make about 4000 pounds of force.

About 60% more.

 

[Caver Dave]

2" ram with a 1.25" rod at 1300 PSI (modded P-Pump) will make about 2500 pounds of force.
2.5" ram with a 1.5" rod at 1300 PSI will make about 4000 pounds of force.

How does that change with 2"-2.5" rams with smaller dia rods... like the TG/PSC?

 

[Bebop]

How so?

 

[R Q]

Reservior Derale Cooling Products 13090 Derale Standard Automatic Transmission Filter Kits | Summit Racing

 

[Caver Dave]

How so?

I assumed given the same input pressure, that the force produced was tied to piston size minus shaft dia.?
So, if the shaft dia. is smaller (3/4"-1"), that would add more piston area/chamber volume over a 1.25"-1.5" shaft... and the pressure would be even more?

 

[Bebop]

I assumed given the same input pressure, that the force produced was tied to piston size minus shaft dia.?
So, if the shaft dia. is smaller (3/4"-1"), that would add more piston area/chamber volume over a 1.25"-1.5" shaft... and the pressure would be even more?

Correct. And the small rod will buckle easier too.

I just didn't understand your question here "How does that change with 2"-2.5" rams with smaller dia rods... like the TG/PSC?"

It changes the same way. Bigger piston area = more force, bigger rod area = less force.

 

[Caver Dave]

2" ram with a 1.25" rod at 1300 PSI (modded P-Pump) will make about 2500 pounds of force.
2.5" ram with a 1.5" rod at 1300 PSI will make about 4000 pounds of force.

Was asking what the above forces look like using the TG/PSC rams with smaller rods?
According to an online calc, it basically doubles the "rod side" pressure...

Pressure acting on rod side
2" Piston diameter - d2 (in)
1.5" Rod diameter - d1 (in)
1300# Cylinder pressure - P1 (psi)
Force Rod Side - F1 (lb): 1787 (2297# delta)

Pressure acting on rod side
2" Piston diameter - d2 (in)
0.75" Rod diameter - d1 (in)
1300# Cylinder pressure - P1 (psi)
Force Rod Side - F1 (lb): 3510 (574# delta)

Pressure acting on opposite of rod side
2" Piston diameter - d2 (in)
1300# Cylinder pressure - d2 (psi)
Force Opposite Rod Side - F2 (lb): 4084

With the above numbers, the force delta for these smaller rod rams are a lot less, so guessing that equates into a "less noticeable" L<>R steering difference running a SE ram?

Correct. And the small rod will buckle easier too.

Also my concern, since stock Jeeps using 11/16" TREs/etc. are obviously a "weak link", 3/4" rods in these rams cause me to wonder about failure rates.
Meaning, outside of NON-contact (bashed into rock) & installer (bad placement/geometry) issues, are y'all seeing regular failures? EDIT: I see @Chris_Keziah was referencing the TG w/ 1.125" rods...

All this is finding my own "warm fuzzy", given the on-road part deciding between:
- 1.5" rod (harder to bend) w/ what appears to be VERY noticeable L-R-performance = keep the SC ram
- 3/4" rod (mounting better be dead nuts or ) w/ what appears to be 400% less noticeable L-R-performance = start over

 

[Caver Dave]

The trail gear 2.25x8 is what I've used in the past

Interesting...
TG Ram above
Pressure acting on rod side
2.25" Piston diameter - d2 (in)
1.125" Rod diameter - d1 (in)
1300# Cylinder pressure - P1 (psi)
Force Rod Side - F1 (lb): 3877

Pressure acting on opposite of rod side
2.25" Piston diameter - d2 (in)
1300# Cylinder pressure - d2 (psi)
Force Opposite Rod Side - F2 (lb): 5169

Force Delta of 28.5%

SC Ram (2" x 1.5" rod)
Force Delta of 78.2%

Pretty sure I know where this will head PDQ

 

[Caver Dave]

Except I'm a DA that can't read...

SC Ram w/ 1.250 rod

Pressure acting on rod side​

Force Rod Side - F1 (lb): 2489

Pressure acting on opposite of rod side​

Force Opposite Rod Side - F2 (lb): 4084

Force Delta of 48.5%

 

[Bebop]

With the above numbers, the force delta for these smaller rod rams are a lot less, so guessing that equates into a "less noticeable" L<>R steering difference running a SE ram?

Correct, since the rod is smaller, it takes less volume, making it a lesser difference from the chamber with the rod to the one without it.