Hydraulics help, loader schematic, information

[Mith]

I think there is something missing in my life. Not a wife, a loader /forums/images/graemlins/laugh.gif
Ive been inspired by pics on the P.F. engineering site and Machine Builders Network to make one. Figure I'll just slap it on the Wheelhorse (poor thing, it will break permanently soon)
Now I figure I can make the frame easy enough (over winter) just dont know enough about the hydraulics yet. John (Densleigh) has given me much advice, just a few more things though.

Has anyone got a schematic for their loader hyraulics that they can post or email me? Would be much appreciated.

Im confused about valves, after reading the army manual from the other hydraulics post Where can I learn about hyraulics? I realised how little I knew.
I think I need it open centre right? For each function (lift/curl) do I need a 2 way or 4 way valve? (I think its the 4 way but dont really know /forums/images/graemlins/confused.gif) Can I just get 2 of the correct valves seperately or is it better to buy them as a block?
I kinda want a joystick but I believe that =£/forums/images/graemlins/shocked.gif. I guess 2 levers would do, I can always form some cable system I guess. Basically what type of valve do I need for double acting cylinders?

What type of pump? The army manual just confused me, gear pump sounds good...... /forums/images/graemlins/crazy.gif Is it obvious I dont have a clue? Rekon about 4-6gpm should do the trick

Ive forgotten how to work out the size of the tank from the pump size, lost Johns PM, anybody care to remind me? Will use the loader uprights to store it.

I attatched a pic of what I think the circuit should be like, please pick away, any things wrong? Also a pic of what I am aiming for.

Anything else Ive missed out?

Thanks for any information, I figure I can blunder about in the dark with hydraulics while I build the frame. /forums/images/graemlins/grin.gif I feel theres gunna be alot of blundering, but thats ok, itll take me ages to build the frame anyway /forums/images/graemlins/laugh.gif /forums/images/graemlins/cool.gif Ive started (looking and headscratching) building a second chassis to fit over the stock one to prevent ripping the tractor in half under load (its already got stress marks from the plough) and front spindle upgrades are only about 4 months away /forums/images/graemlins/smirk.gif, Ive even got a spare gearbox in the shed for when the current one implodes. Im making progress already. /forums/images/graemlins/grin.gif

Sorry for the long post and thanks for any help.

 

[MadReferee]

</font><font color="blue" class="small">( Has anyone got a schematic for their loader hyraulics that they can post or email me? Would be much appreciated.)</font>

PM me with your email address and I will put something together for you. Your diagram is not exactly correct for an open center system as the valves, if seperate, must be in series with each other and the tank.

</font><font color="blue" class="small">( Im confused about valves, ... I think I need it open centre right? )</font>

Most likely, as long as your pump is running continuously.

</font><font color="blue" class="small">( For each function (lift/curl) do I need a 2 way or 4 way valve?)</font>

Using the Prince terminology, you would need 3-position, 4-way double acting spring return to center spools with the work ports blocked in neutral, no detent, with or without float.

</font><font color="blue" class="small">( Can I just get 2 of the correct valves seperately or is it better to buy them as a block? I kinda want a joystick but I believe that =£/forums/images/graemlins/shocked.gif. I guess 2 levers would do, I can always form some cable system I guess. Basically what type of valve do I need for double acting cylinders?)</font>

You will need one valve with 2 spools. The operating mechanism can be 2 control levers or a joystick, it makes no difference, your preference. Just buy what you are most comfortable with.

</font><font color="blue" class="small">( What type of pump? The army manual just confused me, gear pump sounds good...... /forums/images/graemlins/crazy.gif Is it obvious I dont have a clue? Rekon about 4-6gpm should do the trick)</font>

If you get a continuously running pump you should use an open center valve (see above). It's circuit is the easiest to deal with. On pump output, as an example Kubota B2410 and smaller have 4.4 gpm implement pumps. The B2710/B7800/B2910 have 6.4 gpm pumps. Bigger tractors with stronger loaders will have more gpm.

Many people have successfully done what you are attempting. It should be a fun project.

 

[JerryG]

Jim,
Here is the loader part of how the hoses are normally attached. It is from a Koyker model 160.

 

[Mith]

Mad,

I was under the impression that if I had them in series then only one ram would work at once, see where your coming from though, if one valve is in the open centre position it diverts all the flow back to the tank so the others get no flow, right? So I gotta connect the return from one valve to the pressure on the other, but surely if the first valve is on all the way the next one gets no pressure, or does that not matter, actually that makes sense from what happens on excavators ect.

I think having the pump going continuously is the best idea, it seems to be the system most similar machines use that do what I want to do.

Right, valves, if I work this out, corrent me if im wrong-
3 position - Cylinder out/Cylinder in/Open centre
4 way - Cylinder A port/Cylinder B port/Pressure/Return
Spring return - returns to open centre when released
Dont get the bit about blocked in nuetral, or the float bit /forums/images/graemlins/confused.gif

I assume the 2 spools are the fact that there are 2 valves outlined above in a block. Is it going to be more expensive or difficult to find a joystick, that seems easier to use afterall.

Pumps, im probably gunna get away with a 4gpm pump or would I be better going bigger if I want to make like a mower with a hydrualic motor?

Another thing I missed out in the origional post was pressure.
Is the tank under pressure? As im probably gunna wind up welding the box section for the loader out of flat I dont want the welds to break and high pressure hydraulic fluid flying everywhere.
What kinda pressure should I run? 750psi? Most people around here seen to have about 2500, that sounds plain scarey on something ive built personally, could I get away with lower pressure?

One other thing, could I just tee off from inbetween the relief valve and the spool valve to add a circuit for a 3pt lift, I guess I can use the loader valve for lift and angle for the front balde as the loader will be off when the blade is on.

The project has clearly been done many times, look at all the photos on the PF engineering site. I could just buy the plans and save the hassle but I dont have credit cards so I cant. In this case it seems cash is far from king /forums/images/graemlins/frown.gif

Thanks very much for the help /forums/images/graemlins/smile.gif


Jerry, thanks, will help when I get around to plumbing up the cylinders. Any thoughts on curl, 1 cylinder v 2? Price sounds attractive to me, whats the disadvantages.

Man this poor tractor, its gunna be looking like a moving late of spaghetti when it all gets plumbed in /forums/images/graemlins/blush.gif How easy is it to bend steel pipes right?

Thanks for your help, very much appreciated, sorry for the foolish questions but I gotta ask them /forums/images/graemlins/blush.gif /forums/images/graemlins/grin.gif

 

[MadReferee]

First of all a little terminology lesson.

A valve is made up internally of typically 3 or more sections. You have an inlet section, an outlet section and one or more spools. A pressure relief section may also be available. The inlet and outlet are self explanatory. The spools are what does all the work. They are connected to the cylinders via their work ports and are usually controlled by a lever or one direction of a joystick. Physically, the valve design may be a single block of metal that contains everything or a stacked design that allows you to add or remove sections to suit your particular needs, like the Prince SV.

If you buy, and you should, a single valve with 2 spools (a loader specific valve) the plumbing is simple. Tank to pump to valve and back to tank. If you want to add another valve say for a 3pt, it must be connected in series with the other valve (no teeing allowed) and the first valve in the circuit must have power beyond capabilities. This is usually the loader valve which means the 3pt valve comes after the loader valve in the series circuit. In this case the outlet section will have a power beyond port and a return to tank port because you don't want to try and put neutral pressure fluid exhausting from a cylinder back into the high pressure stream.

Prince has good info on all types of valves including loader specific valves. You should be able to get Prince stuff, or something similar in the UK. Look HERE for technical information. Their literature has better explanations than I can give, especially on a 4-way valve, and they show it with pictures too. /forums/images/graemlins/laugh.gif

Fluid pressure will be a function of the system relief valve and the pump. You will never get the loader to work with the low pressure you mentioned.

 

[Mith]

Thanks for the info

So if I get a loader valve, it should have power beyond so I can add a 3pt valve in after it in line.

I attached a revised schematic, hopefully it will be better this time.

From the prince site, I think I need
SP20 gear pump Looks like the one in the first attachment, good spec ect
LVS loader valve It might be worth gettin the LVT because it has all the ports on the top for easier plumbing, have to see the price on that. It has power beyond.
Series 20 valve for 3pt Can stack more for front lift/TnT ect
Spin on filter - 10 micron OK?
Relief valve - is it better gettin adjustable or just set to 2500psi ect?
Cylinders - tie rod vs welded? Im worried about not having them inline, say if my welding isnt straight the loader is slightly tilted which one will take it the best? Not too sure which ones, majestic line looks like the ones everyone else uses, would these be the best option?

That prince site is excellent, the instructions for the valves really help, thanks for the link.

Thanks for your time and patience, very much appreiated, I think I might be getting somewhere

 

[MadReferee]

</font><font color="blue" class="small">( So if I get a loader valve, it should have power beyond so I can add a 3pt valve in after it in line.)</font>

Yes. Valves that support power beyond usually have 2 outlet ports, one PB and one return to tank. The power beyond option is just a sleeve that seperates the internal passages of the 2 ports.

</font><font color="blue" class="small">( I attached a revised schematic, hopefully it will be better this time.)</font>

That's a much better schematic and accurately reflects what you need to do plumbing wise.

Go with the loader valve that has the ports on the top and power beyond. It give you many more options with respect to mounting and future additions.

The SV stackable valve is the one you want for aux operations. It's stackable and has plenty of section options.

The adjustable relief would be better since you can adjust it to suit your application.

Welded cylinders tend to be a bit stronger, and more expensive. Tie rod will work just fine but are a little bigger footprint wise and easier to rebuild/repair. For the light weight loader you are building tie rod cylinders would probably work just fine. Just make sure the port configuration and the fixed end orientation match with your design. You don't want the ports pointing in the wrong direction.

 

[Mith]

Cheers thanks for all your help.
Guess its time to get my behind off the computer and get ordering metal, maybe tomorrow......

Just a few last things

Tank size, pump is gunna be max 6gpm, what size tank do I need? Space is limited so the smaller the better.

Hose, steel v rubber?
How hard is it to bend the steel into shape?
Rubber hosing easier to do?
How do I order it, as a reel of hose, cut it to size and crimp the ends on or do I need to order it with the hose ends attached?
What size is reccomended, I guess you use different sizes for pup-->tank and spools right?
Any advice on picking sizes.

Thats all I can think of right now, I expect Ill have more questions as things happen, thanks very much for your help

Edit, does blocked in neutral mean the ports to the cylinders are blocked off so cylinders dont fall down when valve is in the the centre position?
No detent - no set positions where lever goes, smooth operation from off to on full?
Still dont know what the float is? /forums/images/graemlins/confused.gif
thanks

 

[MadReferee]

</font><font color="blue" class="small">( Tank size, pump is gunna be max 6gpm, what size tank do I need? Space is limited so the smaller the better. )</font>

There are recomendations out on the internet somewhere. I don't exactly know where offhand.

</font><font color="blue" class="small">( Hose, steel v rubber?
How hard is it to bend the steel into shape?
Rubber hosing easier to do?
How do I order it, as a reel of hose, cut it to size and crimp the ends on or do I need to order it with the hose ends attached?
What size is reccomended, I guess you use different sizes for pup-->tank and spools right?
Any advice on picking sizes. )</font>

At 6 gpm 3/8" hose should be fine. You can mix hose and pipe but hose is by far the easiest to work with. Talk to your local hydraulic supplier for fittings, etc.

</font><font color="blue" class="small">( does blocked in neutral mean the ports to the cylinders are blocked off so cylinders dont fall down when valve is in the the centre position? )</font>

Blocked in neutral means no fluid flows to the ports when the spool is in neutral. This does not prevent cylinders from leaking down. For that you will need a double pilot operated check valve either external or built into the spool. I know of no commercial loaders that have these valves on their cylinders.

</font><font color="blue" class="small">( No detent - no set positions where lever goes, smooth operation from off to on full? )</font>

Yes.

One piece of advice and a warning disclaimer. It sounds like you are attacking this project without thinking thru the very basics. Before you do anything I suggest you study up on hydraulics and the mechanical engineering needed to design something of this nature. You need to thoroughly understand what you are doing both theoretically and construction technique wise (ie good welding practices). If you buy plans from a known well designed source then you should be ok but if not then you could do serious damage to your tractor and more importantly to yourself.

Be safe.

 

[Mith]

Thanks for the extra info.

Im not sure what you mean in the last paragraph. I know what the finished product will look like and how it will all work, fit on to the tractor ect. Youre right in the fact that my knowlege of hydraulics lets me down, im not too sure how much force will be exerted on particualr joints, metal sizing ect, I figure thatll come as i work, I will over engineer and measure other stuff to get it right. I think I am able to pull this off but I guess time will tell.
I would buy plans but as previously explained I cant get them. I think the work I am going to do to the tractor will be sufficient to support the loader, if not I can fix the tractor.

Thanks for your concern, if ive missed the point please correct me.
Cheers