How, or can you adjust the power steering PSI on a tractor?

Submitted: Saturday, Jun 19, 2010 at 19:13

ThreadID: 79485 Views:5226 Replies:5 FollowUps:12

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Member - G N (VIC)

Hi All
WE have a 45-66 fiat which is bending the drag link which connects the two front wheels for steering as there is only a ram on one side.
I think that the PSI getting to the ram is too high, as the ram would normaly have some travel left when the wheels hit the stoppers as they are adjustable.
The other reason i suspect too high pressure is that this tractor labours much more than others of the same make / model when the steering is on full lock.
My question is, HOW can i adjust the PSI?, the only component that has any possibility of adjustment, i think, is the unit that sits under the steering wheel, but doe they have adjustment or is it a factory settting?
I think this unit may of been replaced by after market part at some point, Hmmmmmmmm
I amsure there is a machanic or two on here.

Bit off topic i guess, but there was a tractor run accross the country a couple of years ago, so bit relivant!

Regards
GN

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Reply By: Outnabout.. - Saturday, Jun 19, 2010 at 19:46

Saturday, Jun 19, 2010 at 19:46

Have you spoken to an Ag dealer about this or a hydraulic specialist.?

Can't remember if power steer was standard on the Fiat. Could be a full aftermatket kit.

Maybe the pressure is OK but the ram is to long.
This link is an aftermarket supplier under hydraulics they list flow control valves and under the ram section there are some stroke limiting collars. You can also look for other parts by looking at the Fiat/New Holland section.
Another company dealing in after market bits is Bepco.

David

AnswerID: 421453

Follow Up By: Outnabout.. - Saturday, Jun 19, 2010 at 19:47

Saturday, Jun 19, 2010 at 19:47

Forgot to paste the linkbareco Link

FollowupID: 691824

Follow Up By: Member - G N (VIC) - Saturday, Jun 19, 2010 at 20:39

Saturday, Jun 19, 2010 at 20:39

Hi Outnabout

Could not find anything on link, but still interesting site that i didnt know existed, thanks.

See my reply to below as to why i think its not ram stroke, but rather a too higher pressure issue.

does this make sense?

Regards'GN

FollowupID: 691830

Reply By: Roughasguts - Saturday, Jun 19, 2010 at 19:51

Saturday, Jun 19, 2010 at 19:51

might be the pressure releif valve not doing it's job.

AnswerID: 421455

Follow Up By: Member - G N (VIC) - Saturday, Jun 19, 2010 at 20:40

Saturday, Jun 19, 2010 at 20:40

I belief so, but where is the "relief valve"?????
is it in the unit thats connected to the steering wheel?
Is it adjustable or factoiry set?

regards
GN

FollowupID: 691831

Follow Up By: Roughasguts - Saturday, Jun 19, 2010 at 20:50

Saturday, Jun 19, 2010 at 20:50

Thinking the releif valve is in the pump. Can you find an exploded diagram of your pump on the net?

The releif valve is usually only a spring and ball bearing near the bottom of the resevoir filler tank etc.

FollowupID: 691836

Follow Up By: Member - G N (VIC) - Saturday, Jun 19, 2010 at 20:58

Saturday, Jun 19, 2010 at 20:58

Hi Roughasguts

Havnt found an exploded diagram unfortunatly, but it is externaly mounted and has the hydraulic system pump mounted diorectly opposite, which appears to be tha same pump but a bit bigger.
we have replaced the main hyd pump and diassasembled beforee and no relief valves in there at all.
Thts why i recon the relief must be in the unit under steering column, but has it got adjustment?

regards'GN

FollowupID: 691840

Follow Up By: Roughasguts - Saturday, Jun 19, 2010 at 21:35

Saturday, Jun 19, 2010 at 21:35

Just looking at power steering pumps for the fiat and they all include the releif valve so it must be under there and internal somwhere. By the looks of the pump they don't look adjustable, but i beleive there is a filter in there also. So maybe split it open and have a good look and clean it up, must be full of gunge.

Cheers.

FollowupID: 691848

Follow Up By: Member - G N (VIC) - Saturday, Jun 19, 2010 at 21:43

Saturday, Jun 19, 2010 at 21:43

Hi

I will have a look in the pump itself, not sure what to do if its not adjustable?
The units with the problem has a noticable "load up"or drop in revs at idle compared with 2 other units of same model with no steering issues, which makes me tthink its a releif valve setting.

there is a filter in the resevoir

Thanks for info / help

GN

FollowupID: 691850

Reply By: Member - Dennis P (Scotland) - Saturday, Jun 19, 2010 at 20:16

Saturday, Jun 19, 2010 at 20:16

Hi GN,
I would be more inclined to look at the adjusters you mention, sounds like you don't have enough travel.
Even if there is too much pressure in the ram, it shouldn't bend the drag link in normal operation.
Cheers,
Dennis

AnswerID: 421462

Follow Up By: Member - G N (VIC) - Saturday, Jun 19, 2010 at 20:34

Saturday, Jun 19, 2010 at 20:34

Hi Dennis

You are right about "not enough travel" as the ram is on the righ side, but when you turn left, its the left wheel that the stopper hits, but then the ram still has 15mm travel left.

However the book show you can run the stoppers at 3 different positions to give differing max steering angle, so obviously the ram must still have travel available when the wheels hit the stoppers in at least 2 of the positions.

Power steering is std on this model.

Regards
GN

FollowupID: 691829

Follow Up By: Member - Dennis P (Scotland) - Saturday, Jun 19, 2010 at 20:46

Saturday, Jun 19, 2010 at 20:46

Hi GN,
Would you solve the problem by adjusting each side out by 7.5mm?
Might be that the drag link is not screwed far enough into the ram coupling.
Cheers,
Dennis

FollowupID: 691835

Follow Up By: Member - G N (VIC) - Saturday, Jun 19, 2010 at 20:54

Saturday, Jun 19, 2010 at 20:54

Hi

There is not enough adjustment to allow for the extra movement.
But again what about the 3 adjustment settings shown in the book, 2 of them must hit the stopper while there is still ram travel left to go.
i will check the drag link adjustment, but its adjustment is only for toe in so have to have it right length for that.

Regards
Gn

FollowupID: 691837

Reply By: Eric Experience - Saturday, Jun 19, 2010 at 20:57

Saturday, Jun 19, 2010 at 20:57

GN.
The pressure relief is your problem,you can tell that by the fact that the motor is loading up on full lock. The relief valve is in the power steer pump, there is a venturi in the oil flow path to open the valve at high revs otherwise the steering would be very twitchy. When you remove the hex plug be sure to have a clean bucket under it to collect the oil and the piston and spring. Eric

AnswerID: 421472

Reply By: burnsy - Sunday, Jun 20, 2010 at 17:37

Sunday, Jun 20, 2010 at 17:37

I'm not familiar with Fiat power steer systems. Having said that I think you will have a external gear pump with what is called a priority head bolted to the end of it There should be one or two plugs in this head. If you have two one will be the relief valve and the other will be the flow control which as said earlier has a orifice which through that and a spool ensures that the steering receives the same amount of oil at idle as it does at full idle.
If you have only one than both flow and pressure is incorporated into the same spool.
Either way you probably have to remove shims which will be under a stiff spring and not a weak spring which may well be in there too The pressure should be somewhere between 1200 and 1500psi. Usually people complain about too little pressure.

If your tractor has non of this than please forgive me and go looking in the steering box instead.

Regards Mike.

AnswerID: 421564

Follow Up By: Member - G N (VIC) - Monday, Jun 21, 2010 at 09:55

Monday, Jun 21, 2010 at 09:55

Hi Mike

Thanks for info.

I agree with what you are saying and on a larger tractor the pump does have an added section which i assume houses a relief etc.

However i found a danfoss orbital unit diagram on the net which showed it had an adjustable relief valve built in. Then i looked on the orbitalunit on the tractor with issues, NO relief! Then i looked at another tractor same model as one with issues and YES it has a releif on the orbital unit.

I know the tractor with issues has an after market orbital unit fitted, which i belief is the wrong unit for a tractor that does not have the reliefs set up at the pump and this is where all the problem is originating.

I was going to pressure test the lines yesterday but they are some metric type thread, but think i will find in town, just want to prove the PSI is too high before i go any further.

Does what i recon make sense?

Regards
GN

FollowupID: 692019

Follow Up By: burnsy - Monday, Jun 21, 2010 at 19:27

Monday, Jun 21, 2010 at 19:27

Hi GN

Sounds good .
In case you don't already know when you test for pressure you Tee the gauge into the line.
It is HIGHLY unusual not to have any sort of relief in a hydraulic system as when the pump is in good condition it will continue to pump oil until something gives. At best a fitting or hose or at worst the pump ect.
Remember a pump pumps oil not pressure, Pressure only is present when there is a resistance to flow
You may be lucky enough for the pump to be somewhat worn in which case it will bypass internally.
If you still can't find some sort of relief take a trip to your local hydraulics shop and I'm sure they will sort it out.

Regards
Mike

FollowupID: 692053