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chipwitch

Some basic hydraulic questions

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I'm making a 3 pt hitch and have been considering my options for lifting.  They all have their drawbacks.  Hydraulics' is cost.  But, that's where I'm leaning.  I have some parts, but will need to purchase some as well.  I understand the basics, the math, the physics etc, but since I've never worked with them, I've been doing a lot of reading on the net to get the practical side of it.  I have an 8 speed, so I'll be using an auxiliary pump driven by the pto.

 

First thing that confuses me is the use of open circuits vs closed circuits.  I know what they are, but just when I had already decided to use an open system, I read that since 1960, most tractors use the closed system as do construction equipment.  Correct me if I'm wrong, but the kwik-way FEL is open, yes?  Is anyone using a closed circuit on their tractors (excluding those using their transmission as a pump).  I'm guessing no?  Please explain the use of a box blade for grading... is a float detent a desired feature on a hitch?

 

Second thing that confuses me is the float vs detent valves (or at least that's how I've seen it discussed).  A friend told me that on his farm tractor, the 3ph cannot raise the rear wheels of the tractor off the ground, yet he doesn't think the hitch control is a float type.  He couldn't seem to explain this.  To me, it seems it must work one way or the other.   Further, are there detents on a non-float type valve?  If so, where and why? 

 

Thirdly, I'm not sure of the "open center" valve's operation.  Just to be clear, "open center" does NOT mean that going back to neutral relieves the pressure from the cylinder.  I'm assuming this is ONLY to prevent the pump from having pressure on the high side when all control levers are in neutral, returning the fluid to the reservoir?  So, even with the engine off, the cylinders will remain in whatever position they were in prior to turning off the engine, even when loaded (assuming no leaks in the system).  Is there a way to visually distinguish an open center valve from a closed center valve?

 

Fourthly, I have read that some controls are not fully proportional while others are, yet I haven't seen anything like that in the specs.  Are they referring to poppet valves as being NOT fully proportional?  Are those ever used in valve body configurations similar to spool valves?

 

Lastly, I'm working on a 3ph now, but intend to construct an FEL in the near future.  Thus, I'm trying to select a pump that will function universally for anything I may desire in the future.  For controls, I'm planning on using a two spool valve, one with a float detent.  Quick connect fittings will permit me to use the hydraulic system for an assortment of purposes.  When not using the FEL, the hitch would operate using one of the its valves.  Is this a bad idea?  Should I use a third dedicated valve for the hitch?  If so, float or not?

 

Thank you for bearing with me through that long post.

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I'd suggest sending a PM or email to Nick.  If he's got time, he'll be one who can answer all of you questions.

 

An example of his work.....and yes... that's a Lawn Ranger.

 

3ptweb2.jpg  rock015-2.jpg

 

 

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I'd suggest sending a PM or email to Nick.  If he's got time, he'll be one who can answer all of you questions.

 

An example of his work.....and yes... that's a Lawn Ranger.

 

3ptweb2.jpg  rock015-2.jpg

 

 

 

I guess that answers the "down force" question with regard to the hitch!  Very cool

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I tried accessing one of the vids on the Lawn Ranger thread. Seems I cant open it. This Lawn Ranger set up looks awesome.

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Yeah, I think he may have pulled them down. I'm trying to get a hold of him to see if he still has them anywhere that can be posted.

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Gotta say the things that he built for that were very awesome!!

 

I'm sure i'll be referencing his FEL build for my own ...  Good Luck on your 3pt build

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My diesel tractor uses open center hydraulics in that oil is always pumping through the valves and dumping back into the transmission.

 

When you activate a valve, you are just tapping into this flow and can then build pressure.

 

3 point is floating on my tractor. Loader can have down pressure or float depending on valve position.

 

Cleat

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Cleat, do you have a detent float valve for the 3ph?  If so then you have the option to apply down force like the photo in post #2 illustrates?

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