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07-13-2010, 11:04 AM
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#1
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Registered User
Join Date: Jul 2010
Posts: 1
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Hydraulic problems with Case 770
I have a 1970 Case 770 with a front end loader and can't get the loader to pick up big bales of hay. I have suspected the loader wasn't quite normal for some time. The loader works fine on light loads, but won't even try to lift a heavy load. The arms want to creep down at times but not consistently like I would expect if the seals in the lift arms were bad. I replaced the seals in the lift arms a few years ago and put on a different hydraulic pump last year when I had the power shift overhauled. I suspect problems with the control valve or the relief value. I put a pressure gauge in line the lift cylinders and it read almost 1400 psi when the cylinder was fully extended so I think that means the pump is okay and the relief valve is okay. I read on the internet that the control valve has some thermal relief valves that go bad. I don't know where to start. Anybody got any ideas. Thanks
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07-13-2010, 09:42 PM
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#2
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ENGLISH SPRINGER SPANIELS
Join Date: Jan 2010
Location: Hoodoo Valley, Idaho
Posts: 5,449
Liked 3 Times on 3 Posts
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Welcome to the forum! Could it be that the capacity is less than you expect? ie, the loader isn't intended to pick up that much weight?
__________________
Oh Beautiful for smoggy skies, insecticided grain,
For strip-mined mountain's majesty above the asphalt plain.
America, America, man sheds his waste on thee,
And hides the pines with billboard signs, from sea to oily sea. _______________________________________________ Some say I have a bad attitude...... "Screw them!"
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07-13-2010, 10:04 PM
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#3
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Cub Cadet '82' Owner
Join Date: Sep 2008
Location: Parrottsville, TN
Posts: 169
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Quote:
Originally Posted by bfeldh
I have a 1970 Case 770 with a front end loader and can't get the loader to pick up big bales of hay. I have suspected the loader wasn't quite normal for some time. The loader works fine on light loads, but won't even try to lift a heavy load. The arms want to creep down at times but not consistently like I would expect if the seals in the lift arms were bad. I replaced the seals in the lift arms a few years ago and put on a different hydraulic pump last year when I had the power shift overhauled. I suspect problems with the control valve or the relief value. I put a pressure gauge in line the lift cylinders and it read almost 1400 psi when the cylinder was fully extended so I think that means the pump is okay and the relief valve is okay. I read on the internet that the control valve has some thermal relief valves that go bad. I don't know where to start. Anybody got any ideas. Thanks
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Or the spools need rebuilt, you could be getting a lot a bleed-by also.
If you are shure it's not the pump or relief.....
You know also the cylinders may be bleeding by...
Scott
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07-13-2010, 10:07 PM
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#4
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ENGLISH SPRINGER SPANIELS
Join Date: Jan 2010
Location: Hoodoo Valley, Idaho
Posts: 5,449
Liked 3 Times on 3 Posts
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Quote:
Originally Posted by lsmurphy
Or the spools need rebuilt, you could be getting a lot a bleed-by also.
If you are shure it's not the pump or relief.....
You know also the cylinders may be bleeding by...
Scott
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Could check for this, by seeing how long the loader stayed elevated before coming down, could you?
__________________
Oh Beautiful for smoggy skies, insecticided grain,
For strip-mined mountain's majesty above the asphalt plain.
America, America, man sheds his waste on thee,
And hides the pines with billboard signs, from sea to oily sea. _______________________________________________ Some say I have a bad attitude...... "Screw them!"
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07-13-2010, 10:10 PM
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#5
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Cub Cadet '82' Owner
Join Date: Sep 2008
Location: Parrottsville, TN
Posts: 169
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Quote:
Originally Posted by tractor beam
Could check for this, by seeing how long the loader stayed elevated before coming down, could you?
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Yeah, if the valve is bad, spool or relief, it will leak down. Assuming there are no other leaks.
Probably the valve as he suspects.
Scott
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07-17-2010, 11:05 PM
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#6
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Registered User
Join Date: May 2010
Location: Orillia, Ontario, Canada
Posts: 12
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I also suspect control valve spool leakage ...
I just redid the hydraulic hoses and control valves on my old case, before the re-fit it had very low power, could not lift it's own wheel off the ground, even at full throttle.
After the re-fit it pops the front wheel off the ground at idle.
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