Hydraulics help, loader schematic, information

Mith · Aug 24, 2005

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 · Aug 24, 2005

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

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.

( Im confused about valves, ... I think I need it open centre right? )

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

( For each function (lift/curl) do I need a 2 way or 4 way valve?)

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.

( 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?)

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.

( 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)

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 · Aug 24, 2005

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

Mith · Aug 25, 2005

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 · Aug 25, 2005

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 · Aug 25, 2005

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 · Aug 25, 2005

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

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.

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

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 · Aug 25, 2005

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 · Aug 25, 2005

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

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

( 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. )

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.

( 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? )

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.

( No detent - no set positions where lever goes, smooth operation from off to on full? )

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 · Aug 25, 2005

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

candubobby · Aug 25, 2005

unless you have the exact measurement of the pivot to cylinder distance, or you have a cad to work it out, it is almost impossible to get it right by trial and error. Moving the pivot of the cylinder by an inch and affect your curl by 10-15 degrees depending on the leverage you are using.
Unless you have done this before, maybe you should order a plan by sending in a cheque. Any changes you have to make will inevitably costs you a lot more than that. The price of hydraulic fittings are not cheap and you have to be pretty exact when you are plumbing it. I do not know how much it costs for the plans, but I am sure it's worth it.
I design my SKID STEER ( see junkyard skid steer ) with a cad, and even then, have to make a couple of changes that costs me a lot of time. Fortunately, I have all the stuff lying around and does not costs me a great deal of money.

Mith · Aug 25, 2005

Im using ProDesktop, I can get it pretty close on there, the final bit is with the rams on tack in the place I worked out with ProDesktop and try, then retack, weld when right. All this before it even takes a look at any hose.
When I was making the linkage for the plough i made pieces out of wood and cut them before i used metal to get the right lengths for parts, I dont see why i cant do a similar thing to get the right spaces for the rams.
I dont see how it is difficult to move a piviot pin, just grind and reweld the piviot where you want it.
Why do I need to plumb it it before ive tested it my moving it by hand (engine hoist) with the cylinders just in place?
Im not just blundering in blind, I am gunna have some plans on the computer.
The plans would probably about $100 after shipping.

Sorry if this appears a bit irritable, I am most certainly not annoyed, I thank you for your advice.

I attached a pic of the proposed bucket, I havent started designing the frame yet becuase im deciding on the steel to use. Sorry, the dimentions are inside out because of the way I drew it.
Im really not in a rush, ive gotta have something to do over winter afterall

Thanks very much for you insgiht, please advise me on anything ive missed or not got right, I really appretiate the comments, and trust me, I am taking them on board.
Cheers

candubobby · Aug 25, 2005

hydraulic cylinders are almost impossible to extend and contract ( if they are in good working conditions ) at least not 2 inches one that can take 2-3000 PSI. Because of the arm and the curl sort of interact and change the angles, you either have to model it with wood and some sort of extension contraptions or use a cad to simulate the action. When your arm moves up and down, it changes the angles of the curl too. Also the curl / arm mounting point for the cylinder is quite critical ( i.e. have enough clearance. you want to get at least 70 to 80 degrees of curl angles to allow for easy dumping of load when the bucket is raised. Of course all these depends on the max lift you try to achieve and your center point of gravity and how much your tractor weights. I did all the calculations and simulations but forgot the extensions of the hydraulic fittins when the arm is fully raised and have to spend 3 hours grinding away to make it work. ( the cylinders port are slight raised and I did not account for that ).
Of course, my skid is made of junk metals and have to deal with a lot of weird angles and curves. using straight pieces of material will definitely helps a little, NOT A LOT.

Anyway, good luck on the project, like you said, do a lot of tagging before putting the final welds on. I am sure you will run into a couple of surprises.

candubobby · Aug 25, 2005

Sorry, I am not trying to get you upset or imply that you are not capable, just pointing out a few pitfall that a project like this inevitably gets into.

I know I ran into a few problems no matter how careful I was in the design phase.

I did not see the attached bucket you are talking about. Maybe just lost in the post somewhere.

JerryG · Aug 25, 2005

Jim,
I am sure that you can do it, just take your time and measure twice. I am sure someone told Henry Ford that he couldn't do it when he was casting his first engine on the dirt floor of his garage.

Nat · Aug 25, 2005

This may not be revelvant, but in building several dump beds for trucks and trailers I always used my air compressor and a couple spare fittings to test/determin final location of cyl placement. A note of caution when using compressed air the cyl can suddenly extend and go all the way, not like when using hydralic power, so be real careful if you chose to try it.
HTH, latter, Nat

Mith · Aug 26, 2005

Sorry forgot the picutre. Ill put it on this one.

I thought you could push the ram in and out by hand when theyre not connected up, Im pretty sure ive seen it done.
For example for the curl, can i not raise the loader up all the way, fix the curl cylinder to the bucket push it out all the way, tilt the bucket to the desired maximum tip see where the frame end of the cylinder comes to and weld the piviot there. That is the way I figured I would do it.

I havent really thought about cylinders yet, I think working out the length ect will be a function on the CAD. Can I not mark 2 piviot points in pencil, measure with the boom lowered and with it raised. The difference between them would be the extension I need on the ram, then order a ram with that extension?

Im thinking on my feet here.

Trust me, im grateful for your comments, gives me things to think about that I hadnt thougth of before. there are going to be problems even if you follow plans but isnt the whole point being able to overcome the problems.

candubobby · Aug 26, 2005

if they are new and high pressure type, it is very difficult to pull or push ( i.e. impossible ). If you can push them back and forth, the seal is almost gone.
If you are to test it with air, make sure the air is WELL FILTERED and squirt lots of oil in the cylinder before you do it.
If you connect it up to the curl and lift arm, the chances are that the air does not have enough power to lift it, because of the extreme extension or contraction of the cylinder, it is at a pretty steep angle ( you will have to go to the sine/cosine table to work out how many PSI you will need, it will be more than the 125 PSI you are going to get from the compressor. There is some danger in damaging the cylinder also from using air for testing, this is according to the technician that I spoke to that specialized in Seal Selection, it's similar to use oil of too low a viscosity in hydrualics, it will demage the seal, not to mention the amount of comtaminates that can enter the system.
You are absolutely correct in working out all the stuff on the cad first, and if it does not have one that can animate the action of the boom, you can do it with two arcs that is the min and max length of the cylinder and plot the pivots that way.
However, you should look into what is available at what costs in your parts of the woods and get the most economical one, usually the ones on sell or extra stock and cancelled orders from other people, it will save you hundreds of dollars. You can evern try EBAY, but the quality is not assured.
Before you do all that, you should determined the max lift, max weight, that will dicatate pretty well your pivot points for your lift arm, once that is done, just use the two arcs method that I mentioned above and the pivot point will be determined.
For the curl, once you determined the attachment angle, the rest will just follows, making sure that you have enough curl to dump the load when it is raised. It's definitely worth while to get a joy stick, and putting a throttle control ( semi adjustable ) on the curl will make your work 10 times faster.
That way, you can make the raise and curl sort of sychronized, Not being able to raised and curl at the same time with the proper rate with one hand will probably drive you crazy after a while.
Hope this helps, just don't do what I did and did not account for the connector height when the arm is full raised.

Bob

candubobby · Aug 26, 2005

Just had a look at your bucket design. I think it will be wise to copy an existing bobcat one with three sided, it's easier to fabricate and attached, and having a steeper rake at the rear allows your bucket to be closer to the tracter to get the up curl angle you want, plus the added savings in materials and better strength. By having a almost vertical back, you will have to attached fairly high on a pivot point, meaning a much costlier cylinder and takes a lot longer to go thru the curl. You need a pretty fast curl sweep if you use it for moving dirt and clay to dump it completely, otherwise, a lot of it will stay on the bucket.
You will get more volume with your design, but I think if you are to use it in a small tractor, you will run out of lifting power way before you will run out of volume.
Depending on how many HP you have available to you, GPM is not a big thing, Pressure is where it is at. You must first determine the max weight, angles of pivots and leverage, then determine the min PSI that you need. Your GPM will be govern by the HP available.
The formula is HP = GPM x PSI / ( 1300 ) for a gear pump
Pump displacement in Cu In. = GPM x 231 / ( pump RPM )
Once you have all these and you have the diameter of the cylinder and length, you can then determine whether it is acceptable to you in terms of how long it takes to go thru the entire lift curl cycle.
You need a lot less power to curl than lift usually, and make sure you use the push side to lift or curl up if you are at the limit of the hydraulics, depending on the rod diameter, it is usually much stronger on the push side.
Force = piston area x PSI on push but must minus rod area for pull.
Time to entend is = piston area x stoke x .26 / (GPM)

Hope this information is useful and
ALL THESE ARE MERELY SUGGESTIONS.

good luck.

Bob

Mith · Aug 27, 2005

I dont get what you mean with the 3 sided bucket, the bucket looks similar in design to most CUT buckets. Can you draw a digram or find a picture if possible.

The valve I plan on using has regen dump, as a result it should dump really fast. It also has float.
If you take a look on www.machinebuilders.net and hydraulics 101 at the bottom there are some great charts that you can work out all sorts of things. Really useful (thanks Mr Machinebuilders /forums/images/graemlins/wink.gif)

I can think of any way that I could have a ram so that the push side curls up the bucket. Again drawing or diagram would be great!

Thanks, very useful information and great suggestions, its great that you can learn from more knowledgable people, thanks for the forum! /forums/images/graemlins/cool.gif /forums/images/graemlins/laugh.gif