Skid Steer Remote plumbing

[Don P]

I'm trying to figure out how to plumb a remote on the little skid steer. Buying it part by part is sort of like building a VW beetle from parts costwise. I'm going to lift the cab and look for that power beyond cap but I'm thinking I remember seeing it on the existing bucket/boom valve. I'm wanting to hook up a nitrogen charged breaker hammer for now and eventually a grapple for the forks, my low flow pump will work for those. Can y'all look at the diagram and tell me what valve (15) I'm looking for for the control of the remote circuit? This one is a cable controlled footpedal which is one option, my feet are free, but I'm not sure I wouldn't prefer a solonoid switch I can hit with my thumb on the T handle control, really either would work.



 

[Southside]

@mike_belben 

[mike_belben]

Fitting #20 looks to be coming out of your 2 spool loader valve at a power beyond plug and feeding a single spool auxiliary valve actuated by part 15 and foot pedal 21.  


Are you really going to buy all those parts don?  We could put something together much cheaper i'd bet.  I personally would put a DC rocker switch on the control stick and mount a solenoid spool off the power beyond circuit.

[Don P]

Heck no! I'm going to look up a "single spool valve" both manual and solenoid and get the guys at the local shop to match fittings and make hoses for in between. They wanted $647 for part 15 alone  :. This looks way simpler than that.

[mike_belben]

Right.  Good. 

 what do you mean by both manual and solenoid?  Are you rigging up 2 auxiliary setups?  


Whats the gpm on your loader pump.. 10 or so?  -8 lines ?

[mike_belben]

Surplus center ITEM NUMBER: 9-6136

For a single added cylinder circuit using DC toggles only, this solenoid valve should work. It needs to go on a D03 subplate which is $50-100.

 10gpm @3000psi, open center with closed work ports. These have no relief valve so they CANNOT be used downstream of an exhaust port on your loader valve.  They MUST be fed by a power beyond circuit so that the relief in your loader valve still limits total pressure.  You may/probably need a "power beyond plug" for the loader valve to convert to pwer beyond.  Need the part number and mfr of the valve to know for sure.  The port will say "bey" or "pb" next to it and is plugged now. 

[Tom King]

I thought I understood English.

[Sedgehammer]

My bob (bobcat) will not give you factory part numbers on anything. I replaced the main spool valve 2 years ago as the old one was worn out. The factory one had numbers, but the manufacturer wood also not divulge any info it. They said ask bobcat. Factory replacement was no longer manufactured. One wood've thought at that point they wood release part numbers so one could wrench on it. I think they don't, to make you buy a new one. 

Fixed them. Bought a valve that flowed about the same and just remade a little of the linkage.

Point being, he might be in the dark on any meaningful help from the OEM

[mike_belben]

I thought I understood English.

No its not english anymore, we've moved on to SAE since the USD beat out the pound sterling @ bretton woods.   ;D



Relief valves that work on pressure differential look at the pressure in front of and behind the poppet.  Consider a sink full of water with 5 psi in it and zero psi in the drain pipe.  The stopper is tasked with maintaining 5psi in the sink.    If the drain tube backs up due to a clog and gains 3psi, the stopper will now put 3 + 5 = 8 psi into the sink.  


In the kitchen its an overflow, in hydraulics its an explosion because the differential poppet relief cracks at say 2500psi above whatever is on the drain pipe side of it.  You cant put a valve downstream of an exhaust port because thats like putting 2500 psi in the drain so that a 2500psi relief doesnt crack until 5000psi.


It CAN be done this way -multiple valves in series configuration without a power beyond port capable valve- ONLY IF the modifyer is willing to install a total system relief valve just after the pump for full protection. 

 Reliefs are never a bad idea.

[Sedgehammer]

Speaking of. Local national hydraulic shop built my valve. They forgot to put in the relief valve. Started it up and moved the lift arms seemed to be great till we extended the bucket cylinders fully. Cracked the pump and busted 2 of the bucket cylinders. Local manager woodn't due squat. Called the regional manager. Had a check for $1,200 and a new pump. Check was hand delivered by the local manager. 

[Don P]

Thanks Mike,
Sorry it took a bit, I went and poured cores today so we can do some more house jacking later next week.

Just a single valve, I was talking about looking at it both ways, either manual or electric, I'd prefer electric and with the valve you showed, electric is the way to go, wire running to a thumb switch is easier to set up and use.

Looking at the manual I downloaded the pump is 10 gpm and there is a power beyond port. I have found the PB fitting to replace the cap (20).
The factory aux hydraulics run 1/2" line from the PB to the aux valve and 3/8" lines from the valve work ports, I was thinking of just securing hoses to the frame for all of that. My tilt hard lines run down the right arm and they show these running down the left. It looks like I need to check at the strainer and maybe add a T at the strainer end of (17) for return, I'm thinking this needs to be at least 1/2" as well. There is a relief on the loader valve.

[mike_belben]

Youve about got it licked don. Yes, you can tee back into the exhaust line up ahead of the filter. 

 My burnt and salvaged parts pile bobcat has soft hoses up the entire loader where the pipes ought to be.  Had one explode next to me with a full load and put them in firehose thereafter.  I dont care if that firehose sleeve causes the machine to burn.  I never want to be that close to and unprotected from a fluid bang again.  Hardpipe would be better but theres no guarantees in life either.

[Don P]

Thanks for all the help Mike.
Jackhammers are nice but neither of us has healed up yet  :D. Time for a new plan. Some kind of shielding is a good idea, one of the curl hoses blew on me and I thought I had been hit by a rock, luckily it was cold and I had several layers on.

[mike_belben]

On 2nd thought... I said you can tee into the filter but id look closely at your routing and schemetic.


A hydrostatic drive pump doesnt work like open center pump and motor.  The loader valve is tandemed off the back of the left/right drive pumps on mine and loader pump flow is where charge pump pressure comes from to keep the variable drive pumps pressurized under all conditions or they tear up.  Hydrostatic doesnt circulate oil to and from the tank continually like open center.  Instead it circulates from pump to motor to pump to motor to pump to motor for as long as your hold the sticks in travel position, and not at all when youre sitting still running.


 This tiny fluid volume gets hot and dirty so replenishing valves burp some out for cleaning and cooling.  The oil tank on a SS is more like the plastic coolant tank on a new car.  Its only got one hose and the level rises and falls mostly by expansion and contraction.


So my fear is if you route the solenoid aux valve's exhaust side to the filter, that every time you use it, the loader pumps exhaust pressure may drop below the charge pump minimum because the filter and cooler cir uit may be a path of less resistance.  I really dont know and dont wanna steer you wrong.  Look closely at your hyd schematic and try to figure if your loader valve also serves as your charge pump.  Its possible you may have an independant charge pump too.  I dont even know what machine you have.

[Don P]

It's a little Gehl 3825. There is a separate gear pump for the loader bolted on the front end of the drive hydraulic stuff. I'll look over the return side but if return looks tough, I think I could dump it into its own filter and back to tank on its lonesome.

[mike_belben]

Yeah, that triple stack pump configuration with a tandem gear style loader pump is standard.  On bobcat 742/743 and many others the gear pump flow is also the charge pump flow.  The gear pump feeds the loader valve and then the exhaust flow from the loader valve goes back into the drive pumps which have an internal charge pressure relief, probably 30 to 50 psi and its critical for pump life.   If your tandem gear pump has a suction line from the tank direct to it and your loader valve exhaust hose goes to its own filter and back to tank, then it does not provide charge pressure.  Youd have 2 separate hydraulic filters not in common plumbing for that to be the case because the drive pumps need filtration and cooling to. Ive never touched a gehl.



The risk is:  If yours is like mine and you make an additional path around the charge pressure regulator that has less resistance, the charge pressure will drop to whatever that lower pressure is.  Shortened drive pump life will occur.


I think you better determine if the loader return is also the charge pressure first.  That dictates whether you need to add an independant relief valve. Id like to guess a certain way on this but its not worth the risk.  If you have the book or schematics a few pics will probably answer it. Im concerned about giving potentially lethal bad advice.  


How many lines on your hydraulic tank?

[Don P]

Ahh, just one supply and one return, one filter that I know of. Looking at the parts drawing above I think we're ok but I like you're thinking, I prefer to think through "what if I'm wrong". Overconfidence is usually just a lack of imagination. I need to take the boss to Roanoke this morning, it might be a bit but I'll try to find a schematic.

[Sedgehammer]

for a jack hammer electric solenoids are prolly fine. i don't like the lack of control though. I know if running the auxiliary on mine with the foot pedal for long periods gets old, but I do like i can feather things with it.

[Don P]

All good at the Dr's. 4 hours of driving, 15 minute visit but she's doing good.

Shoot me a pm with your email if these aren't big enough. This is my machine. The drawing is later than my early model, I don't have the hydraulic parking brake, the rest looks right but I am not good at reading these;


 

This is the later SX version of the same model that has the auxillary hydraulics, mostly partswise these machines interchange from what I can tell. I think what I'm seeing up front right behind my knees is the system pump, it looks independent of the drives if I'm reading it right.

[alan gage]

Overconfidence is usually just a lack of imagination.

I really like that a lot.

Alan

[mike_belben]

Yeah i cant read the letters no matter how much i zoom.  Plz send to my screen name at yahoo no spaces or anything

[Don P]

Mike, did the manual find you?
I'm thinking the thumb switch I'm looking for is a DPDT momentary contact type?

[mike_belben]

yes, here is what we are working with.  i emailed back this image so you can blow it up as needed.







the system is a hybrid of what i expected.  you have a charge pump, AND, an independent loader pump, whether gear or vane idk but it dont matter.  thats the piggyback tandem thats probably between your knees at the back of the whole complex, facing your feet i assume.   this schematically is in red.  it pulls its own oil from a 100mesh tank line and feeds it to the loader valve block which is at 2500psi.  

BUT... the loader valve exhaust line goes through the filter and cooler and back to the charge pump.. so your charge pump is charged.  interesting.  theres a 15psi relief valve for this and the charge pump has a 150 to 200 psi safety bypass incase that 15psi dump valve fails.  so basically your lowest pressure in that entire system is 15psi (and the highest is 5k so dont let those drive motor hoses ever not have sheetmetal between you and them.)  anything over the 15psi SHOULD go back to tank.   you will have spikes in the loader valve exhaust side thats feeding the drive pump inlet side, such as when lowering something heavy very fast.. the fluid blasting out of the loader has to go anywhere it can.  the charge pump bypass is to keep from puking the seal out of the charge pump, and make the loader able to slam down fast if needed (prevent a flop or whatever.) if that 150-200psi bypass wasnt there is would slow the loader descent speed to only as fast as the 15psi dump to tank would allow.  i guess im getting off the subject.


so yeah, the purple lines are what youre gonna add.  a hose comes out of the PB plug on your loader valve to feed into the P for "pressure" or "pump" port of your aux solenoid.  another hose comes out of your aux solenoid from the "exh" or T for "tank" port,  back to a tee where purple meets blue in the loader valve diagram, and your hydrostatic transmission system wont ever know the aux is there.



if you want a single switch to operate both direction of the aux you want to use a 3 position center off momentary toggle so that its static position is off.  single or double pole wont matter.  you will only use 3 lugs.  the center lug will be connected to battery positive.  the other two lugs will go to their respective solenoid coil end, one pin on each end.  and one ground wire on each spare other solenoid coil lug.  i can draw that if you dont think in words.  

you will push the momentary toggle up or down to open or close the grapple.  but for a jackhammer youll need to hold it.   if thats a terrible burden you can always add an additional standard toggle switch or momentary pushbutton etc in parallel, to whichever side of the solenoid coil you want (think forward/reverse) to turn on the breaker and leave it on.  youre just putting 12v to a terminal to make it go, thats it.  be sure its keyed 12vdc so you dont shut the machine off and grandbaby flip the switch on to burn out your coil.  good news is you can get individual parts for that vickers valve, no need to replace whole thing. theyre very much and industry/MRO standard.

lemme know if anything trips you up. xoxo

[Don P]

Sweet! Got it, that explains much of what I didn't know I didn't know  :D. I could see the feed to the charge pump but that relief around it was blowing my pea, now I unnerstand. Uhh yeah that slam down while pitching forward has been known to happen... and you sure don't want to wait right then.

Surplus center shipped today, still waiting on shipment on the $100 power beyond fitting  , they're proud of that little thing.  I think the rest is the local electric motor/ hydraulic shop, which it looks like I'll be there tomorrow, a tilt hose is getting ready to go, so I'll quizz him if there is anything else I need to get.

THANKS!

[mike_belben]

 

[Don P]

How we spent our holiday weekend  :D


 
We also removed the Gehl "Quick-tach" system and converted to "Bob-tach" so we can interchange with common implements easier, scarfed off the old hookups on my bucket and forks and welded on bob-tach plates.


 
I haven't hooked up to the remotes yet but I can see the hoses hop in each direction... well ok I forgot to hook up the tank return hose and hit the engine, but only for a second, impressive  :D
Thanks Mike!

[mike_belben]

Glad to help don. Most people are just benchracing, Youre one of few who pulls the trigger. 

[Southside]

Don was that quick tac from Titan?

[Don P]

Yes, that and the implement mounting plates came from them. I have mixed feelings. I think I know where new welders go but there was plenty of weld there. It has about 1/8" of twist across the mounting plates but seems to fit into the implement plates ok. The wedge pins were installed backwards, one of the pivot studs for the pin arms was only run in about one thread deep and there was no bottom bobcat style angled piece to fit to the bottom of the attachment plates. All downforce was restrained by the wedge pins so we had to fab that. I'm jacking the front wheels off the ground and dragging backwards half the time so need a real bottom stop to hit the implement plate. There is a slight variation in the 2 implement plates we got so we then had to do a little grinding on our homemade bottom angled piece so it would fit both plates. I'll have the grinder there when we rent the jackhammer in case we need to modify it a little more for standard issue stuff... in other words they aren't hitting real tight specs. The Bob-tach was made to fit a tractor FEL and I'm much narrower so we cut off the excess width and did a little grinding and welding there. However the easy interchangeable mount for my machine was about $1000 more so I'm not begrudging them much. I've got about that in the whole deal here and have remotes now... I see a grapple for the forks on the horizon  :D. It does put my implement forward several inches but we looked under the bottom back of the machine and there is room to put ~4 bf of steel plate under that end without changing ground clearance.

[Southside]

Thanks. I WAS considering one....Guess there is a reason they have the prices they do. 

[mike_belben]

Just remember once you add that rear ballast you will never drive forward up a slope again without an attachment on.  Mine has a 4/4 steel plate  ;D on the rear door and it had foamed tires all around until i completely used them to the bone then put pneumatics up front.  


First time i went bare to fetch an attachment just a slight bit uphill, the front end went skyward and just stayed there. I couldnt get unwheelied and had to shut off before losing oil pickup coverage.

:D

[Don P]

You ain't driving if you haven't gone turtle a time or two  :D

[mike_belben]

I contemplate half tracking the rear of mine. 

 Skid steer prices have gone so stinkin high i can probably never afford a good one now. Ive had enough of the ford gasser and all its constant problems, and have a mercedes om617 turbo diesel inline 5 i would put in but theres no way itll work without an extension of the rear engine house.  It would require a wheelie bar.  Then it donned on me.. a rear bogie rocker and some OTT mini tracks running over small pneumatic idler tires. 

Sizeable project, but worth the time i think. itd probably be a beast.  Id put a belt drive, electric clutched, central hydraulic pump on the pulley end for high flow rotary tools.  Small hotsaw, mulcher etc. 


Probably never happen, too many projects.  

[Don P]

So far the weight balance doesn't seem to be too bad, gonna find out today, I need to load a couple of loads in the dump truck to get it outta there.

I jacked and relevelled a large part of the house a good bit the other day, none of the doors work and I must have landed on something, somebody has died with a vengeance under there  :D. I suspect a critter was in one of the loose stacked stone walls under the kitchen and the weight shifted.

Of course now that its all rigged up with remotes the rock got softer so no jackhammer rental yet. The problem i noticed at the end of the day yesterday Is the long 106" hoses I ran up the arms have been flopping and I've rubbed one already.  I'll zip tie and duck tape it for the time being but that ain't gonna work. I can make a C channel type cover to contain them but I think I want to use hard tubing up the arms with hoses at each end. So of course in my pea brain I figured 1/2" schedule 40 iron pipe would work... a little googling last night on working pressure squished that notion. I found some aluminum tubing, flaring tool and fittings but we're getting out of my wheelhouse, is this adequate?

I'm looking at the 3/8" 3200psi general purpose aluminum here;
high-pressure tubing | McMaster-Carr

Fittings, the nut, ferrule sleeve and straight adapters here;
McMaster-Carr

and the $93.95  37° flaring tool here;
tube flaring tools | McMaster-Carr

[mike_belben]

You want steel tube and flareless compression nuts.  Magical.

[Don P]

Thanks Mike, that saves the price of a flaring tool. I'd have never thought that a compression fitting could handle high pressure, that is magic  :D.