John Deere 2450 steering unit overhaul?

[reb78]

My 2450 steering has been a bit vague for a while. It kinda comes and goes a bit, but having moved a load of bales for my neighbour this evening, it was quite bad driving back down the road to my place and kinda hard to keep in a straight line. Steering rods and links are all ok. In the yard, if i turned the steering wheel slowly, I could get almost 3/4 of a turn before the steering wheels did much! Turn the wheel sharply and they would react faster. I think its potentially to do with the orbital steering unit. Basically, one of these https://www.malpasdirect.co.uk/index.php/591500179-steering-control-unit.html is connected to the steering wheel and sends hydraulic pressure to the steering ram at the front to move the wheels.

Oil level is fine. Steering has no leaks anywhere.

Steering wheel will creep and keep turning slowly if I knock it as i get out of the cab, some searches on google suggest that is relevant...

Does anyone have any idea what the problem might be?

You can see from the price why I would rather avoid a new unit! So, does anyone know if these can be serviced by a competent DIYer? I don't have the gear to measure fluid pressures.

There are seal kits available but they seem to be external seals and it isn't leaking.

(I did find this - in Bulgaria - https://hydrocap.net/en/c/john-deere-kormilno-upravlenie-189/john-deere-steering-unit-al41631-1270 price is reasonable but no idea on quality or how easily I could get it to the UK these days)

 

[sako243]

It may be worth draining the system and refilling. Mate had a similar issue but with a spool valve on the blade on their 5t Komatsu 360. It disappeared after servicing it and flushing through things, his son took an educated guess it could have been a bit of gunk stuck in the valve body. They never found evidence of it but after a refresh of the fluid they never had the issue again.

So it may just be a bit of dirt causing a valve somewhere to stick. Bear in mind this was on a digger that's meticulously serviced and they actually do change the hydraulic oil when they should rather than just the filter.

 

[Rannsachair]

Danfoss originally made steering valves under license from Eaton. The design's are almost identical even after that license ended.

Eaton service manual here:
https://www.eaton.com/ecm/groups/public/@pub/@eaton/@hyd/documents/content/dev_216975.pdf

Will give you an idea if you are comfortable stripping one.

A few possible causes: leaking anti cavitation valve - usually from hydraulic system debris, so clean out and if necessary tap the ball volve against the the seat with a punch and hammer to peen seating area.
Leaking cylinder relief valves: strip and clean.
the steering mechanism itself has no internal seals and relies on very tight clearances.

I used to work with them, see https://www.mig-welding.co.uk/forum...orld-of-the-hydraulic-design-engineer.104969/

 

[reb78]

It may be worth draining the system and refilling. Mate had a similar issue but with a spool valve on the blade on their 5t Komatsu 360. It disappeared after servicing it and flushing through things, his son took an educated guess it could have been a bit of gunk stuck in the valve body. They never found evidence of it but after a refresh of the fluid they never had the issue again.

So it may just be a bit of dirt causing a valve somewhere to stick. Bear in mind this was on a digger that's meticulously serviced and they actually do change the hydraulic oil when they should rather than just the filter.

Fluid is lovely and clean Ed. It's a lot to drain and replace as well as its a shared reservoir with transmission and hydraulics on this.

 

[reb78]

Danfoss originally made steering valves under license from Eaton. The design's are almost identical even after that license ended.

Eaton service manual here:
https://www.eaton.com/ecm/groups/public/@pub/@eaton/@hyd/documents/content/dev_216975.pdf

Will give you an idea if you are comfortable stripping one.

A few possible causes: leaking anti cavitation valve - usually from hydraulic system debris, so clean out and if necessary tap the ball volve against the the seat with a punch and hammer to peen seating area.
Leaking cylinder relief valves: strip and clean.
the steering mechanism itself has no internal seals and relies on very tight clearances.

I used to work with them, see https://www.mig-welding.co.uk/forum...orld-of-the-hydraulic-design-engineer.104969/

Thanks. That's very helpful. It looks simple enough to strip if methodical and doing it on a clean bench?. My workshop manual for the JD suggests you need pressure gear to set it up again after a full strip (think it was referring to of the pressure relief valve was disturbed) - how likely/vital is that?


Will scoring and internal.damage that's causing an issue likely be obvious when I take it apart?

 

[Rannsachair]

Thanks. That's very helpful. It looks simple enough to strip if methodical and doing it on a clean bench?. My workshop manual for the JD suggests you need pressure gear to set it up again after a full strip (think it was referring to of the pressure relief valve was disturbed) - how likely/vital is that?


Will scoring and internal.damage that's causing an issue likely be obvious when I take it apart?

Tough one on relief valves, could leave them til last if no other issues apparent. May be able to count turns on thread till fully in or out to get a rough setting.

The wearing parts are all hardened and ground bar the cast iron housing, so would likely see scoring in housing bore or gerotor tips.

 

[reb78]

Tough one on relief valves, could leave them til last if no other issues apparent. May be able to count turns on thread till fully in or out to get a rough setting.

The wearing parts are all hardened and ground bar the cast iron housing, so would likely see scoring in housing bore or gerotor tips.

Thanks.

I did wonder if that method of count turns in (probably more accurate than out?) would be enough to allow me to set it back where it was.

I'll get a set of seals for reassembly and then see if I can muster the courage to give it a go

 

[Rannsachair]

Thanks.

I did wonder if that method of count turns in (probably more accurate than out?) would be enough to allow me to set it back where it was.

I'll get a set of seals for reassembly and then see if I can muster the courage to give it a go

I did find my old field test instructions for valves:
The following instructions describe how to set and test the integral valves in the field.



Inlet relief valve (open centre units only)



Connect flow source line to "P" port.



Connect return flow line to "T" port.



Block ports "L and R".



Turn input shaft clockwise with 7 Nm torque and maintain torque level throughout remaining steps.



Apply rated flow (11, 23, or 45 lpm) to the inlet port.



Adjust relief valve to desired level - approximately 38 bar per revolution of the adjusting screw. See steering catalogue for adjusting screw location.



Check leakage - reduce supply pressure to 80 % of the inlet relief valve setting and measure leakage from tank port.

Series 110: 1300 cm3/min

Series 230: 1700 cm3/min

Series 450: 2100 cm3/min for pressures up to 172 bar Viscosity: 20 to 26 cSt



Unit should be returned to service if the results are questionable.



Cylinder relief valves - non reaction units



Right turn

Connect flow source line to "R" port.



Connect return line to "T and P" ports.



Block "L" port. Do not deflect valving or turn steering wheel.



Apply 3.8 lpm of flow to "R" port.



Adjust right cylinder relief valve adjusting screw to 60 bar above steering relief valve setting. Steering wheel will turn when relief is activated. Note: with work ports up and facing input shaft end, the right cylinder relief adjusting screw is in the lower right hand corner of the input shaft end of the housing. See steering catalogue for adjusting screw location. 83 bar, (high capacity 117 bar) per revolution of the adjusting screw.



Check leakage - replumb steering unit per steps 1 through 5 from inlet relief valve procedure above. Measure steering wheel rotation (wheel slip) at steering relief valve setting.

Series 110: approximately 5 rpm or less

Series 230: approximately 5 rpm or less

Series 450: approximately 3 rpm or less for pressures up to 172 bar viscosity - 20 to 26 cSt



Unit should be returned to service if the results are questionable.



Left turn



Connect flow source line to "l" port

Connect return line to "t and p" ports

Block "r" port. Do not deflect valving or turn steering wheel

Apply 3,8 lpm of flow to "l" port

Adjust left cylinder relief valve adjusting screw to 60 bar above steering relief valve setting. Steering wheel will turn when relief is activated. Note: with work ports up and facing input shaft end, the left cylinder relief adjusting screw is in the lower left hand corner of the input shaft end of the housing. See steering catalogue for adjusting screw location. Approximately 83 bar per revolution of the adjusting screw.

Check leakage -replumb steering unit per steps 1 through 5 from inlet relief valve procedure above. Measure steering wheel rotation (wheel slip) at steering relief valve setting.

Series 110: approximately 5 rpm or less

Series 230: approximately 5 rpm or less

Series 450: approximately 3 rpm or less for pressures up to 172 bar

Viscosity: 20 to 26 cSt

The Danfoss valve is a closed centre non reation so circuit is:

 

[reb78]

Excellent info. Thanks!

I definitely don't have the kit to do that!!

I wonder.. would an agricultural hydraulics place strip, inspect, clean and reset one of these normally? I'd love to do it myself but I can't reset according to the info above!

 

[Rannsachair]

Excellent info. Thanks!

I definitely don't have the kit to do that!!

I wonder.. would an agricultural hydraulics place strip, inspect, clean and reset one of these normally? I'd love to do it myself but I can't reset according to the info above!

More likely you want a hydraulic specialist, a lot of places were reluctant to touch steering valves when I was in that business 20 odd years ago.

 

[sako243]

Fluid is lovely and clean Ed. It's a lot to drain and replace as well as its a shared reservoir with transmission and hydraulics on this.

So was theirs. Replaced every few hundred hours if I remember correctly.

Your oil capacity isn't that bad... I've got to stomach up for double that capacity just to fill up the JCB's hydraulic system, on top of the cost of an engine rebuild. Hopefully that'll make you feel a bit better.

 

[wyn]

From what i remember with orbital units is the tolerances are very tight.

If you take them apart they might not go back together because the heat from your hands can expand the internal bits.

 

[Rannsachair]

From what i remember with orbital units is the tolerances are very tight.

If you take them apart they might not go back together because the heat from your hands can expand the internal bits.

Aye precision ground on Studer grinders in a temperature controlled environment. As long as parts same temperature they will slide together with gentle rotation.



Closed centre units often have a thermal bleed to heat them up and prevent thermal shock seizure.

 

[reb78]

Wow. Proper close tolerances then - i suppose they cant work otherwise.

I need a steering ram resealed on my digger so might see if these guys would tackle this at the same time - https://swifthydraulic.co.uk/ is this the sort of place who would be likely to look at it?

 

[reb78]

Would I be making a mistake to buy this?

Pardon our interruption...

Neighbour says QTP is usually OK. No idea if they make them or buy them. I can get the current one sorted as and when then. By the time I have paid someone to strip, clean, reseal and reset I'm thinking I won't be far off of the ebay ad figure.

 

[8ob]

Would I be making a mistake to buy this?

At this stage yes. Had an old 3120 that used to mess about like this, they have a a pump driven off the front of the engine which is a lot higher than the trans fluid, a bit of a plugged hydraulic filter /strainer and the pump cavitates they also have some weird flowshare system going on. Worth doing a filter change just to eliminate cavitation/foaming of the UTO and running a few more tests.

This priority valve on the side of the trans case serves the steering.

Bob

 

[reb78]

At this stage yes. Had an old 3120 that used to mess about like this, they have a a pump driven off the front of the engine which is a lot higher than the trans fluid, a bit of a plugged hydraulic filter /strainer and the pump cavitates they also have some weird flowshare system going on. Worth doing a filter change just to eliminate cavitation/foaming of the UTO and running a few more tests.

This priority valve on the side of the trans case serves the steering.

View attachment 452465

Bob

Ah. Ok. I just traced the lines back to that but didn't know what it was! (Was gonna look at the manual when I went in). Could that be an issue and is it serviceable?

No filters on the lines other than. The big hydraulic one next to that valve (that I can see)

 

[8ob]

Ah. Ok. I just traced the lines back to that but didn't know what it was! (Was gonna look at the manual when I went in). Could that be an issue and is it serviceable?

No filters on the lines other than. The big hydraulic one next to that valve (that I can see)

Not sure on the 2450, on the one I had there was a filter/strainer underneath the gearbox, you wouldn't know its there because it goes up inside the transmission case.

One of these

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Bob

 

[Rannsachair]

Would I be making a mistake to buy this?

Pardon our interruption...

Neighbour says QTP is usually OK. No idea if they make them or buy them. I can get the current one sorted as and when then. By the time I have paid someone to strip, clean, reseal and reset I'm thinking I won't be far off of the ebay ad figure.

20 odd years ago there were few steering valve manufacturers: Eaton Char Lynn ( the original) in the USA and Scotland, Eaton Sumitomo in Japan, Danfoss in Denmark, Hydraulik Norde in former East Germany, now owned by Bosch Rexroth and Ognibene in Italy.

When the Eaton factory in Scotland closed, production moved to China (and the machine tools and test rigs), recently Danfoss acquired Eaton Hydraulics. Very likely the cheap units are Chinese, a quick google throws up lots of Chinese copies, I suspect quality will be variable.

 

[reb78]

Hmm. Will take a better look in the manual later.

This is the setup next to that valve.

The black filter is a hydraulic filter. Not sure if the one you mean might be in the green circular housing beneath/behind it. Below-