Help-A-Newby... auxiliary hydraulics skidsteer hack

vinito · Nov 21, 2015

Hi folks.
I just got my first piece of equipment. It's a little Mydra Mac 8A (Gehl 2500). It's going to be a bit of a money pit, but it does work OK as it is. It needs a lot of TLC but part of the reason I got it rather than an already great machine is that I don't know what I'm doing and this was cheap tuition (even though I paid too much for it). My lot is only one acre so it kind of scales down to that pretty nicely really. I just need it for small stuff and a lot of moving heavy things around, so some forks are in my future.

Ugly isn't it? hehe. But it's kind of "cute" too in its way.
So anyway, one thing I think I would like to do to it is to add some auxiliary hydraulics to it someday. Since I don't know what I'm doing, I could use some help figuring out a good way to do this with reasonable economy. I know Gehl and Mydra Mac had a kit to do this, but I would guess that finding one would be extremely unlikely. So anybody know if I can stack another something to my valves, or tap into a line or something to add it? I could possibly add a pulley and drive another separate pump maybe. What might be the best way to start approaching this project?
I am a machinist by trade and generally good with mechanics even though I haven't worked with this kind of equipment before. Hell, I've even made a few dozen parts for loaders and hoes over the years, but I didn't get very deep into knowing much about them as a system.
Thanks for any suggestions.
BTW my into thread is here: (link)

tacboss · Nov 22, 2015

Don't know much about adding hydraulics Just wanted to welcome you and say...that's a pretty neat little machine. Would probably be a fun project to work on.

Tazza · Nov 22, 2015

tacboss said:
Don't know much about adding hydraulics Just wanted to welcome you and say...that's a pretty neat little machine. Would probably be a fun project to work on.

There is always a way, it just depends on how hard or how much it would cost to do.
Have a look at your control block and see if you have a spare segment that you could use. Some have PB ports (power beyond) that you can use to attach another valve to.
You could always use an electric diverter taped into the lift or tilt circuit. The issue with this is that you can't lift/tilt while using the aux hydraulics if you tap into one of these lines.

vinito · Nov 22, 2015

Tazza said:
There is always a way, it just depends on how hard or how much it would cost to do.
Have a look at your control block and see if you have a spare segment that you could use. Some have PB ports (power beyond) that you can use to attach another valve to.
You could always use an electric diverter taped into the lift or tilt circuit. The issue with this is that you can't lift/tilt while using the aux hydraulics if you tap into one of these lines.

I took the seat off today just to have a look underneath. I was pleasantly surprised at how "out-in-the-open" pretty much everything appears to be on this machine. I've been inside a Case and my neighbor's Weldon loaders and both of them are so tight I was glad I wasn't jockeying the wrenches for either one. It looks like it will be very easy to get in and work on anything on this one when it needs it.
I'll look into tapping into and adding a diverter circuit. Seems like that might be an easy and cheap way to go. But I'll look at the control block and see how it's arranged. I have a decent job so I should be able to come up with the parts necessary as long as it can be done. I'll report back and ask for ideas once I have more data to present.
Thanks for the reply.

Tazza · Nov 22, 2015

vinito said:
I took the seat off today just to have a look underneath. I was pleasantly surprised at how "out-in-the-open" pretty much everything appears to be on this machine. I've been inside a Case and my neighbor's Weldon loaders and both of them are so tight I was glad I wasn't jockeying the wrenches for either one. It looks like it will be very easy to get in and work on anything on this one when it needs it.
I'll look into tapping into and adding a diverter circuit. Seems like that might be an easy and cheap way to go. But I'll look at the control block and see how it's arranged. I have a decent job so I should be able to come up with the parts necessary as long as it can be done. I'll report back and ask for ideas once I have more data to present.
Thanks for the reply.

I remember my first machine, there were hoses EVERYWHERE, it was a nightmare getting to the ones i needed to, as they were always at the bottom.
Thankfully, newer machines are not bad for access. Well, not as bad as the older ones, now they just have wiring harnesses that have 50 or so wires running through them...... Have fun finding the issue now!

vinito · Nov 22, 2015

vinito said:
I took the seat off today just to have a look underneath. I was pleasantly surprised at how "out-in-the-open" pretty much everything appears to be on this machine. I've been inside a Case and my neighbor's Weldon loaders and both of them are so tight I was glad I wasn't jockeying the wrenches for either one. It looks like it will be very easy to get in and work on anything on this one when it needs it.
I'll look into tapping into and adding a diverter circuit. Seems like that might be an easy and cheap way to go. But I'll look at the control block and see how it's arranged. I have a decent job so I should be able to come up with the parts necessary as long as it can be done. I'll report back and ask for ideas once I have more data to present.
Thanks for the reply.

I have some data now. First is a link to a few pages in the manual regarding the hydraulics. It's a pdf so hopefully that is handy enough (just the 4 applicable pages): link
Here are some snapshots I took of the valve:

detail of the "logo" on the top:

And here's one showing the space around everything. Not bad.

In case the pdf is problematic or something, let me know. I can upload images of the individual pages. On my browser, clicking on the link above just opens it in another tab.
And by the way, one page has details of a "hydraulic control valve" which I think might be the accessory valve that is part of the auxiliary kit they sold for it maybe??
I'll study it myself for a while too. Maybe I can think of something worthwhile, but I'm a bit doubtful. Seems like with the space available, I might possibly be able to cludge up some kind of new pulley to drive a whole 'nuther pump to drive the auxiliary unless there's a better, more "standard" way to pull it off.
Thanks again for any advice.

vinito · Nov 22, 2015

vinito said:
I have some data now. First is a link to a few pages in the manual regarding the hydraulics. It's a pdf so hopefully that is handy enough (just the 4 applicable pages): link
Here are some snapshots I took of the valve:

detail of the "logo" on the top:

And here's one showing the space around everything. Not bad.

In case the pdf is problematic or something, let me know. I can upload images of the individual pages. On my browser, clicking on the link above just opens it in another tab.
And by the way, one page has details of a "hydraulic control valve" which I think might be the accessory valve that is part of the auxiliary kit they sold for it maybe??
I'll study it myself for a while too. Maybe I can think of something worthwhile, but I'm a bit doubtful. Seems like with the space available, I might possibly be able to cludge up some kind of new pulley to drive a whole 'nuther pump to drive the auxiliary unless there's a better, more "standard" way to pull it off.
Thanks again for any advice.

Hey.
I just found a bit on installing the auxiliary kit. It's not a lot of info and the pictures are marginal at best. I ordered what is supposed to be a service manual which will probably be here the end of next week, so maybe I'll have some more detailed data on it.
Here is a pdf link on the installation of the aux kit: link
But it looks like they are just installing Tees off the hoses and installing a new valve. Is that correct? and if so, is that a good idea? Seems like that might be dead simple if it would work well. I can make linkages and control pedal or whatever.

vinito · Nov 22, 2015

vinito said:
Hey.
I just found a bit on installing the auxiliary kit. It's not a lot of info and the pictures are marginal at best. I ordered what is supposed to be a service manual which will probably be here the end of next week, so maybe I'll have some more detailed data on it.
Here is a pdf link on the installation of the aux kit: link
But it looks like they are just installing Tees off the hoses and installing a new valve. Is that correct? and if so, is that a good idea? Seems like that might be dead simple if it would work well. I can make linkages and control pedal or whatever.

I was just thinking that another option would be to install a whole new 3-spool valve stack on the machine too couldn't I? Not sure if taking away the "stock" part might be something to avoid or not, but it looks like there are several choices on eBay for around $120 to $175. Of course I'd probably have to engineer some paths for linkages and such so maybe another route would be less hassle. Just throwing out another idea.

SkidRoe · Nov 22, 2015

vinito said:
I was just thinking that another option would be to install a whole new 3-spool valve stack on the machine too couldn't I? Not sure if taking away the "stock" part might be something to avoid or not, but it looks like there are several choices on eBay for around $120 to $175. Of course I'd probably have to engineer some paths for linkages and such so maybe another route would be less hassle. Just throwing out another idea.

That was my first thought. That is how most machines do aux. hydraulics, with a 3 spool control. may take a bit of adapting, but it would be the most hydraulically reliable. Cheers - SR

1ofU · Nov 22, 2015

Vinito :
Welcome to the site ,
I'm 1.5 hr's ne of KC.MO in Carroll county rural Bosworth area if you ever want to meet another member of the site ,
you can drop me a line i build attachments for my bobcats /backhoe aswell .
aswell as hydraulics for both of them . a welder by trade but i have my own fab shop at home and can pretty much can handle about any project you may need help with .
1 of U
Jess

Tazza · Nov 23, 2015

1ofU said:
Vinito :
Welcome to the site ,
I'm 1.5 hr's ne of KC.MO in Carroll county rural Bosworth area if you ever want to meet another member of the site ,
you can drop me a line i build attachments for my bobcats /backhoe aswell .
aswell as hydraulics for both of them . a welder by trade but i have my own fab shop at home and can pretty much can handle about any project you may need help with .
1 of U
Jess

Replacing the valve isn't a bad idea, you have lots of room. You would be happier with "real" aux hydraulics and not tapping into the lift or tilt circuit.

vinito · Nov 23, 2015

Tazza said:
Replacing the valve isn't a bad idea, you have lots of room. You would be happier with "real" aux hydraulics and not tapping into the lift or tilt circuit.

That's the direction I'm leaning now as long as I can get the proper configuration. I see from the parts diagram that one spool is a 4-way and the other is a float. Not sure what all this means, but I'm trying to learn. So I guess I need to duplicate what I have within reason and add one more which can drive either motors or cylinders. I'm assuming that the stack should be open center too and spring return and no detents for all circuits. Since I didn't know how varied this can become, I didn't know to look for the configurations of the valve stacks I saw on eBay, but it seems possible that I could pretty easily waste money on something that won't work if I'm not careful.
I keep thinking the other (maybe simpler) option since I have some space in there is to add a pulley and drive a whole 'nuther pump just to run the auxiliary. This would necessitate only a single spool valve and never interfere with the rest of the hydraulics other than the extra load on the motor. Maybe that's just goofy - seems like a proper hoe does fine with a dozen circuits running off one stack. I guess I was thinking this might be pretty in-line with the rest of the design of this machine since the wheels drive off individual pump/motor assemblies per side from one pulley and the bucket off a pump coupled off the motor shaft. So I have three pumps on the thing already.
Hmm. More thinking is in my future.

SkidRoe · Nov 23, 2015

vinito said:
That's the direction I'm leaning now as long as I can get the proper configuration. I see from the parts diagram that one spool is a 4-way and the other is a float. Not sure what all this means, but I'm trying to learn. So I guess I need to duplicate what I have within reason and add one more which can drive either motors or cylinders. I'm assuming that the stack should be open center too and spring return and no detents for all circuits. Since I didn't know how varied this can become, I didn't know to look for the configurations of the valve stacks I saw on eBay, but it seems possible that I could pretty easily waste money on something that won't work if I'm not careful.
I keep thinking the other (maybe simpler) option since I have some space in there is to add a pulley and drive a whole 'nuther pump just to run the auxiliary. This would necessitate only a single spool valve and never interfere with the rest of the hydraulics other than the extra load on the motor. Maybe that's just goofy - seems like a proper hoe does fine with a dozen circuits running off one stack. I guess I was thinking this might be pretty in-line with the rest of the design of this machine since the wheels drive off individual pump/motor assemblies per side from one pulley and the bucket off a pump coupled off the motor shaft. So I have three pumps on the thing already.
Hmm. More thinking is in my future.

I think that you would still be better off with a 3 spool control. The float function is of limited use on a skidsteer, so if you had to give that up, it wouldn't be the end of the world. You are correct that your machine has open center hydraulics, and all of your functions will be 4-way, 3 position, spring return. Your current control has a built in pressure relief, so be sure you source one with a relief valve, pretty common. Here is another place to source a valve: http://www.surpluscenter.com/ That way you don't have to feel the pressure of buying the wrong thing off of eBay. HTH - SR

vinito · Nov 23, 2015

SkidRoe said:
I think that you would still be better off with a 3 spool control. The float function is of limited use on a skidsteer, so if you had to give that up, it wouldn't be the end of the world. You are correct that your machine has open center hydraulics, and all of your functions will be 4-way, 3 position, spring return. Your current control has a built in pressure relief, so be sure you source one with a relief valve, pretty common. Here is another place to source a valve: http://www.surpluscenter.com/ That way you don't have to feel the pressure of buying the wrong thing off of eBay. HTH - SR

Yea that might be a better way to go for a source. I for sure would rather pay $500 too much than spend two or three days converting and adapting stuff, changing hoses with ends to suit the valve, etc. just to find out it won't work.
Sorry for my stupidity, but I could use some help picking out the valve then. Here's the specs from the owner's manual for the bucket hydraulics:
Pump - wear-compensated gear pump, 7.25GPM @ 3000RPM, 2000PSI capacity
Valving - lift and tilt with float detent on full lift, 20GPM capacity
I don't know what the relief setting is at, but I would guess it's 2000PSI or sligthly less? I'll hopefully be able to find out more specifics when the (supposed) service manual arrives.
In case it matters, the engine is rated 22.5HP @ 3000RPM
My first curiousness is why the valves are rated at 20GPM capacity when the pump maxes out at 7.25GPM @ full engine RPM ?? Is there that much wiggle room or am I missing something.
If I am supposed to match the valves to the pump GPM, then this valve looks like a possibility: (link)
But if I need to be up around 20GPM on the valves, then this one looks interesting, though maybe it would require a major change to the control lever: (link)
My machine has almost entirely 3/8 hoses for pressure stuff so I'm not sure if either of those are quite matched.
Anyway, that's a lot to digest. Any guidance is most appreciated. And thanks muchly for the advice offered thus far.

vinito · Nov 23, 2015

vinito said:
Yea that might be a better way to go for a source. I for sure would rather pay $500 too much than spend two or three days converting and adapting stuff, changing hoses with ends to suit the valve, etc. just to find out it won't work.
Sorry for my stupidity, but I could use some help picking out the valve then. Here's the specs from the owner's manual for the bucket hydraulics:
Pump - wear-compensated gear pump, 7.25GPM @ 3000RPM, 2000PSI capacity
Valving - lift and tilt with float detent on full lift, 20GPM capacity
I don't know what the relief setting is at, but I would guess it's 2000PSI or sligthly less? I'll hopefully be able to find out more specifics when the (supposed) service manual arrives.
In case it matters, the engine is rated 22.5HP @ 3000RPM
My first curiousness is why the valves are rated at 20GPM capacity when the pump maxes out at 7.25GPM @ full engine RPM ?? Is there that much wiggle room or am I missing something.
If I am supposed to match the valves to the pump GPM, then this valve looks like a possibility: (link)
But if I need to be up around 20GPM on the valves, then this one looks interesting, though maybe it would require a major change to the control lever: (link)
My machine has almost entirely 3/8 hoses for pressure stuff so I'm not sure if either of those are quite matched.
Anyway, that's a lot to digest. Any guidance is most appreciated. And thanks muchly for the advice offered thus far.

Sorry, I wish I could edit my previous posts.
They have this one which seems like it might be a pretty close match to the original in case the previous two are not.
25GPM capacity, 3/4NPT in/out, 1/2NPT work ports, 1 2 & 3 double acting with #1 having a detented float position. (link)

vinito · Nov 23, 2015

vinito said:
Sorry, I wish I could edit my previous posts.
They have this one which seems like it might be a pretty close match to the original in case the previous two are not.
25GPM capacity, 3/4NPT in/out, 1/2NPT work ports, 1 2 & 3 double acting with #1 having a detented float position. (link)

By the way 1ofU, Hi and thanks for the hospitality.
I build stuff too. I am a machinist for a power plant and get to make all kinds of one-off stuff for all the millions of parts a power plant needs and in a wide scale range. It's pretty fun most of the time. I have done a fair bit of fabricating in previous jobs and for myself, but since I'm in a union shop now we actually suffer a bit of trouble if we (machinists) weld anything company related rather than have the welders do it. Doesn't stop me for my own projects though.
Most of my home stuff is smaller. In fact, seems like the only thing I've used my own shop for the past few years is to keep the lawnmower running. But I hobby with electronics, 3D printers and RC flying things. And now I'm studying hydraulics !
Which reminds me, I wanted to assure you guys that once I nail down what to purchase to get this auxiliary hydraulics going, I should be able to follow through on the installation and plumbing on my own rather than badger you to death on every little detail. And I promise to show pictures !! especially if I get an auger going (which I could really use) and eventually a hoe attachment. Heck, a grapple would be relatively easy compared to either of those and pretty handy as well.
And since I'm adding a post, I could expand on the previous one that the last valve I linked to also has open center and a relief valve set at 2000 but adjustable between 1500-3000. That might just be the one I need. I would like to know what's up on the difference between the flow ratings for the valve and pump if anybody knows off the top of their head. Just curious I guess.

Tazza · Nov 23, 2015

vinito said:
By the way 1ofU, Hi and thanks for the hospitality.
I build stuff too. I am a machinist for a power plant and get to make all kinds of one-off stuff for all the millions of parts a power plant needs and in a wide scale range. It's pretty fun most of the time. I have done a fair bit of fabricating in previous jobs and for myself, but since I'm in a union shop now we actually suffer a bit of trouble if we (machinists) weld anything company related rather than have the welders do it. Doesn't stop me for my own projects though.
Most of my home stuff is smaller. In fact, seems like the only thing I've used my own shop for the past few years is to keep the lawnmower running. But I hobby with electronics, 3D printers and RC flying things. And now I'm studying hydraulics !
Which reminds me, I wanted to assure you guys that once I nail down what to purchase to get this auxiliary hydraulics going, I should be able to follow through on the installation and plumbing on my own rather than badger you to death on every little detail. And I promise to show pictures !! especially if I get an auger going (which I could really use) and eventually a hoe attachment. Heck, a grapple would be relatively easy compared to either of those and pretty handy as well.
And since I'm adding a post, I could expand on the previous one that the last valve I linked to also has open center and a relief valve set at 2000 but adjustable between 1500-3000. That might just be the one I need. I would like to know what's up on the difference between the flow ratings for the valve and pump if anybody knows off the top of their head. Just curious I guess.

I'm wondering of the valve is rated for 20GPM is to keep it cooler, ir just what they got a good deal on when building the machines.
I see no reason why you can't run it closer to the size of the pump, 7.5GPM, so aim for 8-10?
I agree that the no float feature isn't a deal breaker, i have used it maybe twice.

SkidRoe · Nov 23, 2015

vinito said:
By the way 1ofU, Hi and thanks for the hospitality.
I build stuff too. I am a machinist for a power plant and get to make all kinds of one-off stuff for all the millions of parts a power plant needs and in a wide scale range. It's pretty fun most of the time. I have done a fair bit of fabricating in previous jobs and for myself, but since I'm in a union shop now we actually suffer a bit of trouble if we (machinists) weld anything company related rather than have the welders do it. Doesn't stop me for my own projects though.
Most of my home stuff is smaller. In fact, seems like the only thing I've used my own shop for the past few years is to keep the lawnmower running. But I hobby with electronics, 3D printers and RC flying things. And now I'm studying hydraulics !
Which reminds me, I wanted to assure you guys that once I nail down what to purchase to get this auxiliary hydraulics going, I should be able to follow through on the installation and plumbing on my own rather than badger you to death on every little detail. And I promise to show pictures !! especially if I get an auger going (which I could really use) and eventually a hoe attachment. Heck, a grapple would be relatively easy compared to either of those and pretty handy as well.
And since I'm adding a post, I could expand on the previous one that the last valve I linked to also has open center and a relief valve set at 2000 but adjustable between 1500-3000. That might just be the one I need. I would like to know what's up on the difference between the flow ratings for the valve and pump if anybody knows off the top of their head. Just curious I guess.

The control is oversized to compensate for the return flow that hydraulic cylinders can generate. When you retract a cylinder, you are returning more flow than what you are pumping in because of the volume of the cylinder rod. Combine this with gravity, when you are lowering the boom, and the volume that the control is seeing is quite a bit more than the 7.25 gpm that your pump is capable of. The valve that you are looking at should fit the bill nicely. Cheers - SR

vinito · Nov 23, 2015

SkidRoe said:
The control is oversized to compensate for the return flow that hydraulic cylinders can generate. When you retract a cylinder, you are returning more flow than what you are pumping in because of the volume of the cylinder rod. Combine this with gravity, when you are lowering the boom, and the volume that the control is seeing is quite a bit more than the 7.25 gpm that your pump is capable of. The valve that you are looking at should fit the bill nicely. Cheers - SR

Thanks for the advice, guys.
I keep sitting here thinking and now I have created a new wrinkle. My head is buzzing with goofy ideas and I believe it might be cool (and simple) to hack the bucket attachment pins with a cylinder so that I could change attachments without leaving the seat. It's just an opposing, inline pair of pins arrangement to release/attach the bucket, etc. I'm just thinking that since I'm in the middle of this anyways, maybe I could pull that off pretty easily by purchasing a 4-spool valve instead. They have two that should work - neither has a float detent (but as mentioned, not a deal-breaker) and one has 12GPM max with the desired relief valve range (and ooooh, it's a stack), and another one with 20GPM max monoblock but it has no relief valve, and also would be slightly easier to mount. Can a relief valve be added to a valve block or is it more complicated than that? The one without the relief valve is about $160 less so would absorb the cost of the relief valve if it's possible to just add one into the system or whatever.
Or of course, is this just getting stupid and I should be slapped? Don't hold back.

Help-A-Newby... auxiliary hydraulics skidsteer hack

Help Support SkidSteer Forum:

Well-known member

Member

Moderator

Well-known member

Moderator

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Moderator

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Moderator

Well-known member

Well-known member

Similar threads