3-Point Hitch Hydraulics for Dummies / Newbies

[TableRocked]

I searched the forums and couldn't find anything dumbed down to my level enough.

Planned tractor purchase: One of the TLB's from Kubota - not firm yet on how big is big enough

Planned Tractor Attachments:

3pt hitch log splitter
Hydraulic breaker 200 ft-lbs from Kubota
4in1 Bucket on the front and/or a grapple
Hydraulic thumb on the backhoe
Reverse Rotary Tiller
Wood Chipper
Post Hole Digger
Box Blade

My question:

I've seen when adding front and reverse hydraulics you can choose the type of valves you want. How do I know what valves I need? What does double acting valve vs. float detent valve mean as far as work I could or couldn't do?

 

[k0ua]

A double acting valve just allows you to throw the valve lever both directions, so that fluid will flow out of the A port when you throw the lever one direction and then out of the B port when you throw the lever the other way. You will be able to "feather" the fluid flow by partially actuating the lever. Obviously when fluid is flowing out the A port for instance then if you are controlling a double acting cylinder for instance, fluid is coming out of the cylinder on the other side of the seal and flowing back into the tank thru the B Port.

A Float detent control, will allow you to push fluid to a cylinder either way just like a double acting valve but if you push it into the detent position it will allow fluid to be pushed back by the implement. In other words it is in "float" It is not holding pressure on the line, The implement is moved to where it was left, but in the detent position the fluid is free to push back. An application for this could be a hydraulic top link where you have a bush hog on and you want the bush hog to "float" over the terrain as now the top link is not rigid while the valve is in the float detent position. A lot of folks that use a lot of ground engagement equipment advise getting at least one or more float detent valves.

 

[k0ua]

By the way, I am no expert on this and there are guys on here that are.

But here is another example, Say you are using a back blade, and you have a top and tilt set up on your tractor. Lets say you are putting a crown on a dirt or gravel road. You might go thru and set the tilt of this back blade with your tilt cylinder to crown the center of the road. You would leave you float detent valve in the spring centered position after you got your angle set. This will leave the fluid in the cylinders and lines pressurized and the blade angle will stay set. Now you have made some holes and gouges, and some loose materiel and you want to smooth it out. You could now go over it again with the valve in float detent, so that the blade just floats on its own weight on the materiel dragging the loose material into the holes, but it wont dig in because if it encounters any real resistance it will float over that resistance.

This is what I think anyway. If some of the guys that really have and use these features come along, listen to them.:thumbsup:

 

[TableRocked]

Sorry, "top and tilt"?

Thanks that example makes sense....so a bush hog, for example, you'd always want to have a float valve? Whereas if you were back dragging with your FEL, you'd likely want to be able to "force" it a bit under pressure... so will a float valve do everything a double acting valve will do and more?

Which of the above implements does one type of valve make more sense than the other?

.....sorry these are dumb questions and I'm sure if I was fortunate enough to have my tractor, I'd have figured this out......I enjoy learning as much as I can ahead of the purchase....spreads out my purchasing enjoyment.....

 

[k0ua]

Sorry, "top and tilt"?

Thanks that example makes sense....so a bush hog, for example, you'd always want to have a float valve? Whereas if you were back dragging with your FEL, you'd likely want to be able to "force" it a bit under pressure... so will a float valve do everything a double acting valve will do and more?

Which of the above implements does one type of valve make more sense than the other?

.....sorry these are dumb questions and I'm sure if I was fortunate enough to have my tractor, I'd have figured this out......I enjoy learning as much as I can ahead of the purchase....spreads out my purchasing enjoyment.....

your front end loader, henceforth known as a FEL will always already have a float position on the lift .. so for this discussion we are discussing rear remotes and their associated valves.
so will a float valve do everything a double acting valve will do and more? Yes, It just has a dentented position at the end to allow the valve let fluid flow freely in and out the work ports.

Top and Tilt, henceforth known as TnT. As your tractor comes from the dealer , it will have a jackscrew for top link adjustment. and a jackscrew or a special crank adjusted jackscrew for a right side link. This top link attaches into one of several holes on the back of the tractor chassis, and the other end goes onto the top of your implement to make the 3rd link of your Three Point Hitch. Henceforth known as the 3PT. (please try to keep up with all the acronyms) The other 2 links are the lower links on the tractor, sometimes called the pull links. You now have 3 points of contact with the implement. The top link is adjustable and the right hand lower link is adjustable in position up and down independently of the main hydraulic lift which lift both lower links
together.

So when we put a TnT kit on we replace the top jackscrew with a double acting hydraulic cylinder and the right side jackscrew with a hydraulic cylinder. The hydraulic cylinders are plugged into remotes on the back of the tractor. These remote outlets are controlled by Selective Control Valves, (henceforth known as SCV) that are either regular double acting valves or Float detent control valves. So far so good?

In normal backdragging you do not want downforce on the bucket. You normally use the weight of the bucket to do the smoothing. Hence the float detent position in your normal loader valve setup. This is the way they all are going to come from the Manufacture.

But on your TnT setup you may wish to float some implements at some times, hence the recommendation for the float detente valves in some position by the "experts". I don't have any, and nothing I do really requires them. I just have the one normally double acting valve, and right now I have it plumbed up to my FEL to use as a grapple controller.

 

[Dirthog]

No small tractors have down pressure on the three point hitch that i know of they all basicly float in the only force you have is up. Now for a 4 +1 bucket or grapple you will need two way flow on the front. The same for a thumb IF you want a hydraulic one on the backhoe. the Hammer is different you only need one way flow and most want a free flow back to tank to help with restriction and heat.

 

[k0ua]

One downside to a detented float valve would be when you actuate the valve you could inadvertently go into float mode if you shoved it to far into the detent position. Now you may have to start over with positioning your cylinder if the pressure was released due to gravity acting on your implement and you would have to start over to get it where you want it.