Detent vs normal hydraulic port question

[MAD777]

I'm planning a tractor purchase soon. This is all new to me as I retire & move from city to country. I will need extra rear hydraulic outlets, but I have no clue as to the appropriate use of detent vs normal ports.

The implements I'll be using are a grapple, fed from rear auxiliary ports, which I need only to open & close the jaws, no fine tuning.

And a box blade, attached to a hydraulic top link, to feather the fore & aft pitch of the box blade.

Finally, a rear mounted snow blower, which may have a hydraulic function to rotate the chute.

My question is, which type of ports do I need?

 

[/pine]

I'm planning a tractor purchase soon. This is all new to me as I retire & move from city to country. I will need extra rear hydraulic outlets, but I have no clue as to the appropriate use of detent vs normal ports.

The implements I'll be using are a grapple, fed from rear auxiliary ports, which I need only to open & close the jaws, no fine tuning.

And a box blade, attached to a hydraulic top link, to feather the fore & aft pitch of the box blade.

Finally, a rear mounted snow blower, which may have a hydraulic function to rotate the chute.

My question is, which type of ports do I need?

Just to clarify...there are two basic types of detents...one will just hold the valve open in one direction or the other and "float" detent will allow the device cylinder to remain where it meets resistance...

The former is mostly used on things like log splitters etc...where the float position can be taken advantage of with hydraulic side links and some attachments...

 

[MAD777]

So, the plot thickens! Glad I asked. I guess the question should read, normal, detent directional, or detent floating.

 

[muddstopper]

Pine is pretty much correct. A detent is simply some sort of locking mechanism that keeps the valve in one position for hands free operation. The valve can be detent in both directions, or just one direction and spring centered in the other. A auto return wood splitter valve with detent is one example of a valve that self centers in one direction, meaning you have to keep your hand on the lever to control the cyl, and detents in the opposite direction for hands free return. There is also a added feature in a auto return valve of a detent release. A detent release can be mechanical, hydraulic or electrical mechanism that automaticly releases the detent when a certain pressure or position is met as per system requirements. A loader valve may have a spring centered in both directions with the addition of a detent for float position in one direction. This would mean the cyl could be manually moved to a fixed position in either direction or placed in a detent float position if needed. Anyways, there are a ton of different valve combinations, just depends on what you are trying to do.

 

[LouNY]

On a new tractor with a loader normally the loader lift and lower function will have a float detent, it will allow some back blading work that way.
As far as the rear remotes, a float detent is usefull if anything has a single acting cylinder, IE some haybines and tedders and planter will have single acting cylinders for lift and lower by gravity, only need one hose. It allows for equipment to be ground following.
A valve with directional detents has uses for hydraulic motors motors and can be used as a power beyond function if an attachment has it's own valves on it, such as a backhoe or splitter.
My personal preference is for 3 or 4 rear remotes, I like one with directional detents, and all others to have a float detent, you may not have a lot of choice in the matter depending on the tractor,mine had 3 rear remotes standard, one with directional detents the other two have no detents or float position unfortunately.

 

[MAD777]

Well, there's more to it than I anticipated. Am I correct in saying that a hydraulic top link (on the 3pt) should have a centered detent? Would this allow me to extend it to where I want it, then release the lever and the top link will stop & hold that position, while the lever re-centers itself?

 

[JRobyn]

A normal control valve will do that.

Sometimes, with not-the-best-quality control valves (including some OEM valves) the valves leak internally and the implement (the cylinder) will not stay EXACTLY where you put them. This can be a problem, for example, for your "tilt" cylinder with a box blade or bush hog for obvious reasons. The best solution for this that I am aware of is a small, separate in-line shutoff ball valve. Can go anywhere in the line downstream of the control valve.

A float detent position is a great idea for ALL of the rear remotes (IMHO) mainly for the reason that adding this feature over non-float is usually only a nominal additional cost. It is particularly useful for the top link cylinder for bush hogs to allow "ground following".

Brian from Fit-Rite Hydraulics (a site sponsor) will be along shortly to explain better!

 

[MAD777]

I appreciate everyone's input. As a complete beginner, this is surprisingly difficult to wrap my head around. Everything else about tractors seems relatively straightforward by comparison. The many nuances of these hydraulic ports are confusing for someone like me with no experience to fall back on.

 

[muddstopper]

A normal control valve will do that.

Sometimes, with not-the-best-quality control valves (including some OEM valves) the valves leak internally and the implement (the cylinder) will not stay EXACTLY where you put them. This can be a problem, for example, for your "tilt" cylinder with a box blade or bush hog for obvious reasons. The best solution for this that I am aware of is a small, separate in-line shutoff ball valve. Can go anywhere in the line downstream of the control valve.

A float detent position is a great idea for ALL of the rear remotes (IMHO) mainly for the reason that adding this feature over non-float is usually only a nominal additional cost. It is particularly useful for the top link cylinder for bush hogs to allow "ground following".

Brian from Fit-Rite Hydraulics (a site sponsor) will be along shortly to explain better!

One way to stop the "drift", and take a little load off the control valve, is to use cyl with built in counter balance valves. Dont usually see such cyl's on TnT setups. With a regular cyl, you are depending on the CV to stop the flow from leaking pass the spool to keep the cyl in place. When the spool gets a little wear, fluid leaks by and the cyl will start to drift under load. If a hose bust, the cyl with load can drop. A counter balance vale requires pressure before fluid can leave the cyl. Think of it like a relief valve that stays closed until a certain pressure is met and then it opens to release the flow. It will have a check valve bypass that will allow free flow in one direction, for extention for example, but requires pressure on the rod end port to open the piston port and allow oil to return to tank. You will see this kind of system on a boom truck where it could be necessary to keep a cyl at a fixed position and hold a load in the event of a hose burst. A counter balance valve wouldnt work with a float valve, but most tractors 3pt lift arms will already allow for float as they dont have down pressure anyways. In fact, off the top of my head, I cant think of a reason to have float on a TnT cyl. I would think float on the toplink when hooked to a bushhog or scrape would allow the top of the implement to fall forward as soon as the tractor moved forward.