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Old 10-04-2006, 08:43 AM   #1 (permalink)
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Need less turns lock to lock...

Right now I love my full hydro setup except for one thing. It takes too many turns lock to lock. Right now I'm at approximately 6 one way and 8 the other way. It's great for street driving but it gets annoying offroad when you're turned all the way left and need to get all the way right quickly. Let me know if I'm wrong but I'm thinking the easiest way to remedy this problem is just to step up my orbital.

Right now I'm running a Danfoss OSPB 80 ON with a 2.5" single ended Chief ram. My pump is the stock Jeep P-pump with the WTO mods. Here are the specs I was looking at...

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Last edited by redneckengineered; 10-04-2006 at 08:54 AM.
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Old 10-04-2006, 09:47 AM   #2 (permalink)
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yea i think the easiest would be the orbital... or a tiny ram
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Old 10-04-2006, 10:01 AM   #3 (permalink)
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Need more info about your ram (stroke length, and shaft dia.)
I'm assuming that your using an 8" stroke, with 1.25" shaft.

If so, the danfoss with 7.63 in/rev will give you
3.86 revolutions in one direction, and 5.15 revolutions in the other.


if that's still not fast enough, the valve with 9.76 in/rev will give you
3.02 revolutions in one direction, 4.02 in the other.
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Old 10-04-2006, 10:04 AM   #4 (permalink)
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Quted from my article:

Step 12 - Decide on the approximate number of turns lock-to-lock desired.

Depending on vehicle usage - street driven, trail only, rocks, mud, etc. and personal preference / driving style this number will vary - usually from about 2 to 6, with 4 being a reasonable value for street/high speed driven rigs and 2-3 for dedicated trail/rock rigs.

Step 13 - Calculate the required displacement of the steering unit per revolution in order to achieve the desired # turns lock-to-lock (DP) (cu. in / rev.)

DP = V / N where:

V = Swept Volume of full stroke from step 10 (cu. in.)

N = number of steering wheel revolutions lock to lock

Note: If using a a single unbalanced cylinder, this value will have to be calculated for both head and rod sides of the cylinder, and a decision made as to which to satisfy, leaving the other side with either more or less turns to lock than desired.

Step 14 - Select steering unit from those available, note actual displacement, and re-calculate actual number of turns lock-to-lock.

Because step 13 may yield a number not actually specified by any manufacturer it is necessary to select the closest possible displacement, and re-calculate the actual number of turns lock-to-lock the system will have.

N = V / DP where:

N = number of steering wheel revolutions lock-to-lock

V = Swept Volume of full stroke from step 10 (cu. in.)

DP = actual displacement of steering unit (cu. in. / rev.)

Again, note that this figure will differ between left to right is a single unbalanced cylinder is used.

Step 15 - Determine maximum required steering input speed (SS) (rev. / sec.)

You must determine how fast the driver must be able to turn the steering wheel and still have full steering power (if the driver turns the wheel faster than this, a dramatic increase in steering effort is felt as the power assist of the hydraulic fluid is unable to keep up)

The minimum normally considered is 1 rev/sec (60 rpm). This depends on the safety considerations for avoidance of obstacles under minimum and maximum flow conditions during all speed possibilities of the vehicle. 1.5 rev/sec (90 rpm) is common, and 2 rev/sec (120 rpm) is considered about the maximum input speed achievable by an average person (go ahead and try and turn your steering wheel faster than 2 revolutions per second and get back to me if you can :-)

It is important to take into consideration the number of turns lock-to-lock calculated in step 14. This is because what you really want to determine is how quickly you can turn the wheels lock-to-lock. For example, if you have 4 turns lock-to-lock (average) and wish to be able to steer the vehicle fast (2 rev / sec.) what you are really wanting is to be able to steer lock-to-lock in 2 seconds:

4 turns L-L / (2 turns/sec) = Lock-lock in 2 seconds

Therefore, you can achieve the same steering speed with 2 turns lock-to-lock and a steering input speed of 1 rev. / second.

Step 16 - Calculate required pump flow. (QP) (gallons per minute)

QP = SS x DP x 60 / 231 where:

QP = required flow of pump (gpm)

SS = steering speed (rev. / sec.)

DP = Steering unit displacement (cu. in. / sec.)

Note: When using an open-center steering unit connected with pump directly, maximum pump flow should be less than 1.4 times the steering unit rated flow. Higher flow into steering unit increases pressure-loss of the steering system.

This step is probably the most likely entry point for those reverse-engineering a system, as the limiting factor is likely to be the pump used. That is to say, it's not as if there are suitable pumps available with an infinite range of flow rates. It should not be too hard to take the flow rate of your pump, and reverse the equations to calculate what sort of steering speed, number of turns lock to lock, size of cylinder to use, and steering force are supportable. The other option is to use the excel spreadsheet below and keep tweaking all the variables until satisfied.

Or play with values in the on-line calculator:

https://www.pirate4x4.com/tech/billav.../Steering.html
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Old 10-04-2006, 10:29 AM   #5 (permalink)
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too bad your orbital was not further away or if there was a way you could place this before it.

steering quickener.
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Old 10-04-2006, 10:50 AM   #6 (permalink)
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When you get a faster orbital, you then will need a better pump

Drive mine, when we meet in Alabama. Im 2 1/4 turns stop to stop. I love it.

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Old 10-04-2006, 10:56 AM   #7 (permalink)
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Spaggy and Billa, thanks for the info. I got it now. Spaggy, you were right in your assumptions. It's a 2.5" x 8" ram with the 1.25" shaft. I'm thinking the 9.76in/rev is the one to go with.

Can anyone with a similar setup to mine comment. Is 3 revolutions one way and 4 the other too fast or just right. Thoughts?
Thanks


edit: Dan, you think my pump won't keep up? I did the WTO mods to increase flow and it seems fine as of now. I'd like to know before I spring for a new orbital. I'd hate to have to get a new pump too.
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Last edited by redneckengineered; 10-04-2006 at 11:03 AM.
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Old 10-04-2006, 11:01 AM   #8 (permalink)
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7 turns to 3 turns is a big difference, i doubt that pump would be able to handle that
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Old 10-04-2006, 11:06 AM   #9 (permalink)
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I'm sure someone has tried the 9.76in/rev orbital with a stock pump. I'd like to hear how it worked out.
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Old 10-04-2006, 11:27 AM   #10 (permalink)
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Another suggestion would be to change the ram out for a 2" diameter (if you feel that it will still have enough muscle for you).

A 2x8" ram, with a 1.25" shaft will have the following turns (lock to lock) with your current orbital.

Direction 1 - 3.14
Direction 2 - 5.15

There are a few chief rams on surpluscenter.com starting at $69 that may work for you.

http://www.surpluscenter.com/item.as...name=hydraulic

http://www.surpluscenter.com/item.as...name=hydraulic

http://www.surpluscenter.com/item.as...name=hydraulic

http://www.surpluscenter.com/item.as...name=hydraulic
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Old 10-04-2006, 11:29 AM   #11 (permalink)
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The 160 is OK with a flow-modded P pump if everything is in good shape, belt-driven at a good ratio, etc.
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Old 10-04-2006, 11:42 AM   #12 (permalink)
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Quote:
Originally Posted by spaggyroe
Another suggestion would be to change the ram out for a 2" diameter (if you feel that it will still have enough muscle for you).

A 2x8" ram, with a 1.25" shaft will have the following turns (lock to lock) with your current orbital.

Direction 1 - 3.14
Direction 2 - 5.15
Thanks for the tip but I actually just upgraded to the 2.5" for more turning power. This is the classic example of one mod leads to another.

Scott, appreciate it. I did the West Texas mods so flow has been increased. Hopefully that will be enough because I'm trying to avoid getting a new pump. What are the signs that the pump can't keep up and needs to be upgraded? I'll watch it closely.
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Old 10-04-2006, 12:01 PM   #13 (permalink)
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Originally Posted by redneckengineered
What are the signs that the pump can't keep up and needs to be upgraded? I'll watch it closely.
Sluggish steering. You'll still have plenty of power, the wheel just won't turn as fast as you're trying to turn it. More likely at idle than otherwise, but it's not necessarily a serious problem; depends on how you 'wheel for whether it's important (to you--it's your $$).

No (or significantly decreased) power = bad pump, needs rebuilt or replaced, typically.

Running too big an orbital for your pump, won't hurt the pump or result in quicker pump wear or the like, it'll just make it feel like it's steering slow.
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Old 10-04-2006, 12:07 PM   #14 (permalink)
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Great. Thanks Scott. I posted in the Misc For Sale section. Here's hoping someone has the OSPB 160 ON and thinks it's too quick. I'd like to trade someone if possible.

PM me for what you can sell that orbital for in case I can't trade for one. You've always been really helpful.
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Old 10-04-2006, 02:44 PM   #15 (permalink)
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Originally Posted by [email protected]
Sluggish steering. You'll still have plenty of power, the wheel just won't turn as fast as you're trying to turn it. More likely at idle than otherwise, but it's not necessarily a serious problem; depends on how you 'wheel for whether it's important


Scott is describing the effect perfect.

Letting out of the throttle to slow down for a fast turn is the most noticible time.

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Old 10-04-2006, 04:06 PM   #16 (permalink)
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Quote:
Originally Posted by Dan Dibble
When you get a faster orbital, you then will need a better pump

Drive mine, when we meet in Alabama. Im 2 1/4 turns stop to stop. I love it.

Dan

yeah...ive been wanting to do this too...so...well, i guess i need to abus...er....drive your rig too...yeah, thats right...
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Old 10-04-2006, 06:00 PM   #17 (permalink)
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Originally Posted by p575
yeah...ive been wanting to do this too...so...well, i guess i need to abus...er....drive your rig too...yeah, thats right...

Save your pennies, that may be possible soon

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Old 10-05-2006, 07:58 PM   #18 (permalink)
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I don't have a danfoss valve to look at but on the eaton valves I just change the pump plate and gear on the end , just be careful not to loose the check ball in the pressure port, some have a screw in retainer and some have an extended tip on the bolt, I've changed many from 4.5 to 11.7 and different combinations with no problems at all, a good tip , find some worthless 5 port valves and grab the gear plates, just make sure its not a power beyond valve, those are not worthless if you go rear steer.
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Old 10-05-2006, 08:32 PM   #19 (permalink)
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Originally Posted by millerxc
I don't have a danfoss valve to look at but on the eaton valves I just change the pump plate and gear on the end , just be careful not to loose the check ball in the pressure port, some have a screw in retainer and some have an extended tip on the bolt, I've changed many from 4.5 to 11.7 and different combinations with no problems at all, a good tip , find some worthless 5 port valves and grab the gear plates, just make sure its not a power beyond valve, those are not worthless if you go rear steer.
This is also an option, just make sure that if you're trying to interchange gear sections, that you go same-brand--CharLynn/Eaton don't interchange with Danfoss, for example.

Also, if you get it back together with the gear section timed incorrectly to the valve section (there's a thread I posted some time ago on this very subject), when you power it up, it'll either shake, or dive to one side, and won't work right. If that happens, it's one tooth off on the dogbone interface, rotate the gear one tooth on the dogbone, and you're good.
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