I have a John Deere 2755 and the rear lift works fine going up but it will it will not come down without weight to force it down. The lines feeding it pulsate and jump when going down. Is it possible to get air in system that will not work it's way out?
Hyd. System
- Thread starter Graper00
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Thomas
Epic Contributor
- Joined
- Apr 6, 2000
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- 31,056
- Location
- Lebanon,NH.
- Tractor
- Kubota B2650HSD w/Frontloader & CC LTX1046 & Craftman T2200 lawn mower.
Hows the hydraulic fluid level and has the hydraulic filter been change lately?
I'm not sure on JD's,but on some Kubota there a knob one turns for the hydralic flow,and one must make sure that knob turn or we encounter what your facing now.
Let me know what you find out for I'm interested.
Have fun and enjoy some tractor time./w3tcompact/icons/cool.gif
Thomas..NH
I'm not sure on JD's,but on some Kubota there a knob one turns for the hydralic flow,and one must make sure that knob turn or we encounter what your facing now.
Let me know what you find out for I'm interested.
Have fun and enjoy some tractor time./w3tcompact/icons/cool.gif
Thomas..NH
TomG
Platinum Member
- Joined
- Apr 6, 2000
- Messages
- 610
- Location
- Ontario
- Tractor
- Ford 1710: Loader, Hoe, Snowblower, Box scrapper & 3ph Forks
As Thomas mentioned opening the flow control knob probably will solve your problem. As you may know, few 3ph's have down-pressure. Most are lowered by the weight of an implement, and the flow control valve governs how fast an implement goes down.
If you're new to this stuff, you may not be aware that most hydraulic systems contain a priority control valve that determines which hydraulics get pressure. Priorities differ from tractor to tractor, but my remote gets priority over the 3ph. The hitch won't lift if I'm using the loader. I never figured out the power steering priority. Some 3ph's can feed a rear remote. On my Ford 1710, there is a detend (notch) at the top of the 3ph lever travel. You don't want to put the 3ph lever in this position unless you're using the remote.
Regarding air, tractor hydraulic systems are open, unlike car brake systems. Air in a line or cylinder tends to be pushed through the system to the reservoir where it bubbles out of the oil. Usually cycling a cylinder (moving it from fully extended to fully retracted, and holding it the end positions for a few seconds) will clear a cylinder. However, abnormal operation can produce oil cavitation where many fine air bubbles are introduced into lines. The result is weak hydraulic operation. The bubbles compress under pressure. You shouldn't see cavitation unless there are restrictions in the lines, a bad pump or a partially clogged filter.
If you're new to this stuff, you may not be aware that most hydraulic systems contain a priority control valve that determines which hydraulics get pressure. Priorities differ from tractor to tractor, but my remote gets priority over the 3ph. The hitch won't lift if I'm using the loader. I never figured out the power steering priority. Some 3ph's can feed a rear remote. On my Ford 1710, there is a detend (notch) at the top of the 3ph lever travel. You don't want to put the 3ph lever in this position unless you're using the remote.
Regarding air, tractor hydraulic systems are open, unlike car brake systems. Air in a line or cylinder tends to be pushed through the system to the reservoir where it bubbles out of the oil. Usually cycling a cylinder (moving it from fully extended to fully retracted, and holding it the end positions for a few seconds) will clear a cylinder. However, abnormal operation can produce oil cavitation where many fine air bubbles are introduced into lines. The result is weak hydraulic operation. The bubbles compress under pressure. You shouldn't see cavitation unless there are restrictions in the lines, a bad pump or a partially clogged filter.
