Backhoe Backhoe Questions

[SPIKER]

hi again:

I'm back: that is the relife valve you have dissassembled there. there SHOULD be a smaller screw under the cap part that is on the far left of the photo. it (on MINE) has a slotted screw drver head & lock nut under the cap and as you turn it tighter it pusheds on the shiny shaft part on the left, which in turn pushes aginst the spring which pushes aginst the cone shaped part on the far right which is pushed aginst the internal cone to seal off the fluid presure and increase it higher.. the cap part is just a cover on mine and there is a lock nut (probably ~14 mm) around the slotted head bolt. the lock nut is loosened and screw tightened to increase the pressure. once set you tighten the 14mm nut down, then the cap is reinstalled and the big lock nut 22 mm I think is tightended to retain the cap.

ok anyhow a pressure gauge adapetd to fit into one of the work ports or hoses would work 0~2500 PSI gauge should surfice to adjust the pressure max the lever to that hose out and read the pressure, increase the pressure of the spring aginst the cone/seat to increase the working pressure inside the lines.

I seem to hink you MAY have cavitated the pump possably bruning it up which would hapen very fast if no fluid was in there and the pump ran...

what I do is to back over the hoe sub frame and get as close as possable to the pump lines and then hook up the pump. I can then raise /lower the hoe frame using the hyd pump controls. NEVER unhook you're lines unless 100% needed. the lines are long enough to get it on/off by rotating the pump up and over aginst the hoe after removing it. air into the pump is BAD. one other thing is you MAY have a air leak on the suction side of the pump (missing o-ring on the pump to hose block? ) this would mean it sucks air though and will usually FOAM like dish soap! ask JOHN S about this /forums/images/graemlins/wink.gif sorry john had to mention it /forums/images/graemlins/smile.gif /forums/images/graemlins/wink.gif

now anyhow any air in the system will mean it can't move and or will have very little pressure untill the air is compressed... air is #1 enimie of hydraulics... (even worse than water!)

anyhow I hope that helps some...

MarkM /forums/images/graemlins/crazy.gif

 

[slorne]

John,

Thank you. I posted a couple of photos of the BH pv early today. I have located the same PV on the front end loader.

I dont have much knowledge about pv operation. I am wondering if once the pv releases, if you then have to completely disassemble and reinstall?

I will try this tonight. Also, I wonder of I should try to start the tractor and enguage pto to see if fluid comes out of the hole where pressure valve is currently removed? I would just enguage for 10 seconds or so... What do you think?

Thanks Again

 

[slorne]

Mark,

Thank you for the very good description. a couple of questions:

1. do you know how much pressure should be in the bh lines?

2. I am wondering if there could have been a rubber washer / gasket in the hydraulic line connection (female) which screws on to the pump? - mabey it fell off?

3.i am now starting to think the pump may be bad
a. but it circulates fluid in the tank
b. shoots a stream out with the one side hydraulic line off

I have probably spend 10 hours trying to figure this out. Once I get it fixed, I will post something with the results and solution.


Thanks

 

[schmalts]

Hi, if you are getting fluid to circilate in the tank your problem is not the pump, or air in the lines. This can only be one thing, the fluid is bypassing. There has been many other guys who have had the same problem with dirt in the bypass valve. Take it apart and clean it up good. There is probably a burr or dirt on the spring loaded vavle hanging the thing up. Dive in, take it apart and maybe carfully check to see if it moves free in the bore. I know of guys who had to shim the spring by adding a washer too. Be careful though, setting the pressure too high equals bent or busted rams and frames. There is some adjustement if i remember correct. If you do not have a place to put a guage set it light just for safety and move up from there. Once you get the pressure relief problem fixed you can back start to adjust it by backing the screw out until the outriggers will not lift the hoe up, and then dial it up until it just can. this will be a minimum setting of pressure. of course the best way is to do with a guage but that is not always possible.
If you do find you want a new pump i happen to have 2 of them!! one from a spare i never used, and second is a lightly used one that i have because i went to a prince pump when i rigged the hoe up to my Kama.
Call me if you want a spare, 262-388-2809 Pat

 

[slorne]

John, Mark, Spiker, Bulechip, Schmalt, etc...

I think I have it figured out...

1) When I removed and cleaned the BH PV I only took out the bottom (the photo attachments)

2) After scratching my head, and scratching my head, I went back and reread this whole posting

3) Made a list of all the advice

4) Went back to Johns link http://johnstractor.com/HoePump.html and realized there was a top part of the BH PV valve with another cone and spring

As soon as I removed the screw, spring, and cone I saw several pieces of what looked like rice. They turned out to be metal shavings.

I used a magnatized philips screwdriver and removed them all. I will now reassemble and see what happens.

I am encouraged with this finding and could not have done this with out all of your help.

If anyone is interested in a photo of the metal shavings, I can post the picture.

I'll try to update after reassemble and test tonight.

Thanks Again

 

[slorne]

Good news / Bad news

Well I reassembled the BH PV assembly after removing the metal shavings. The following happened:

1) Stabilizers raised and lowered no problem at 1K rpm

2) Tried to curl the bucket / move boom and nothing?

3) Reved up the engine to 1500 rpm

4) Bang... the pressure side of the hydraulic pump blew out
a. it cracked all the way across the side and a waterfall of fluid came out

At any rate, I am really happy to have figured out the 1st problem with the PV- with everyones help. Now I think there could be two other issues?

1) More metal shavings in the other controls?

2) I installed the BH PV valve with the adjustment with too much pressure?

Any advice on rpm for backhoe operation and what should be the pressure in the system?

I am definitly buying a pressure gauge and want to get this thing right.

The joy of a crate tractor. And the other good news is that I am learning about the machine.

thanks again...

 

[JohnS]

Slorne,

I will say you have the right attitude for this. /forums/images/graemlins/wink.gif

</font><font color="blue" class="small">(
4) Bang... the pressure side of the hydraulic pump blew out
a. it cracked all the way across the side and a waterfall of fluid came out
)</font>

Wow, its hard to believe that pressure would build up and break there! I would have expected a hose to go first. Be careful. If a pressure failure, you were lucky you were not hit with any metal or high pressure hot fluid.

When you were raising the stabilizer arms, did you hear the relief valve working when it was in the full up position, at the stop? ie just trying to prove that the valve was working and not jammed.

Recommend calling Pat and getting one, if not both of his spare pumps. Disassemble the failed pump at see if anything can be learned there. Try flushing and cleaning the lines, as best you can while waiting for pump to arive. Flush and check the tank for these chunks. Check the suction side screen, to make sure there is not any gapping holes, that will allow for it to be recirculated. When you start again, use low rpms, and do as Pat suggests above. Start from a very low setting proving the valve is working, and adjust up. As far as a pressure gauge, you may have to get some fittings made.

PS: Please post a picture of the split pump when you have a chance.

 

[Boltonpower]

The metal shavings are in the actual gate of the check valve. To
properly clear them you should remove the spring and plunger
from the top AND the tension balance pin from the bottom.
Then you should remove what you see AND excercise the
gate with a probe, a 6mm hex key works well for this. I blow
them out with compressed air to make sure it's clear. It
sounds like the PR valve wasn't working for you to blow up
the pump. Remember the load on the pump is static at
2,200 psi. If the PR valve is set for a higher pressure the
pump can be over loaded and something will give. Did you
replace the bottom part of the valve before "testing" That is
a key companent of regulating the gallery pressure in the valve body.
It's possible that debris is in the other spools but
usually it's just the PR valve..

Graham
Bolton Power Equipment

 

[slorne]

Graham,

Thanks for the info. I will replace the pump tomorrow and first I plan on doing the following:

1) Removing all caps under each control fitting and checking for more metal shavings

2) Flush out the tank and clean filter

3) Do you use a pressure gague to set the pressure or just the small adjustment method? What is the suggested setting?

Also, once I get this tractor together it will go to my father's small farm about 50 miles from your location.

Would your business be able to service this for him in the future as he is not that mechanically inclined?

Thanks

slorne

 

[slorne]

photo of broken pump housing

 

[SPIKER]

slorne:
sorry about the blown pump: #1 reason i suggested setting up a pressure gauge inline... anyhow

#2 there should be an o-ring under the small metal bracket/hose fitting on eash side of the pump between the 4 bolts that hold the fitting to the pump and the fitting. there is a grove cut in them. all of the hoses have o-rings between the hoses and the flat mating surface of the cylinders & fittings too.

more than likely the pump was damaged prior to the PV blow out. the metal more than likely came form the pump? had to come from someplace. I would removing the pump inl;et & outle hoses and cleaning them inside with flush & air. same for tank if possable use long magnetic pickup tool to forage for debris. dissassemble the valves and do the same for them if (IF) you find much more than flakes the sice of metal flake paint.

keep up the work it will be rewarding SOMEDAY /forums/images/graemlins/smile.gif

MarkM

 

[schmalts]

**** that sucks. I knew you would find crap in the PR valve from the other things you told me(fluid moving in tank)
It is possible that you replaced the PR valve and had screwed it in all the way or too far. Like i said, if you dont have a guage dont worry about doing it the way i said, you cannot hurt anything by having it set too light.
Start with the PR valve set almost all the way out, then work the outiggers until they just have enough power to lift the tractor off the ground. do small incriments until you achieve this. Then go have a little fun and if you find the hoe is not able to dig like it should make small adjustments. Remember, skill is everything with hoe operation. if you never used one before dont attempt to just push the bucket into the ground because everything is done by touching the bucket down, then pulling the main boom towards you to fill the bucket about half way, then curl the bucket and it will fill the rest of the way. That is the proper low stress way to work it.
Do you need a spare pump?

 

[Boltonpower]

Suggest the following:

1) Take the dead pump apart and see there is any
indication that it took a piece of metal from
the suction side.

2) Drain tank (if you haven't done this) and remove
the suction strainer. Check to make sure it isn't
compromised somehow.

3) I would have a "Tee" made up to test the pressure
since there seems to be some question about what it is.
The fittings on the pump are Seal LOC type 18mm X 1.5mm
You can guess if you want but you risk a hydrualic
explosion if it's way to high. The system is rated at
16 mPa or about 2,300 psi. I wouldn't screw with that.

4) After putting the gauge "Tee" in line I'd back off the
cap nut on the underside of the PR valve and with
the tank filled so you can see the oil start the engine.
watch the gauge carefully. The 2,300 is max so at idle
it maybe a little less.

5) watch the gauge carefully and crank the cap nut in. The
pressure should rise. The oil should be moving from the
right side of your tank to the left. I'd set it at about
2,000 psi max.

6) After you know you have good pressure and flow in the
valve gallery then you can test for issues with the
induvidual spools. Lets get that going and safe first.

Yes I do service. I'm in central Mass, where is your fathers tractor??

Graham

 

[JohnS]

I am surprised that it didn't just blow the pump seal, like on the engine mounted pump (very similiar design). That casing is fairly thick. Went through to the bolt hole and out.

Did it stall or load down the engine significantly? When you dead head the engine mounted pump, it will load or stall engine.

 

[slorne]

John,

I have given alot of tought to what happend with the pump after I found the metal shavings and cleaned out the PR valve. I'll list what I think happend:

1) Cleaned out the PV, which was definitly the problem

2) Started, enguaged PTO and tried moving stablizers

3) They moved - lifted bh off the ground

4) Then they did not work the second time

5) I slightly tightened PV - thinking there was an inital burst of fluid, but then not enough pressure

6) Nothing - So I turned up the RPM's - and bang

I think the error was probably the following

1) too much pressure (PV too tight to begin with)

2) First action from stablizers was a result of the metal shaving being removed and fluid flowed briefly

3) Tightening and increasing rpm overloaded the system

Tomorrow I will clean all controls, the tank, filter, replace all fluid. Then start with a very loose pv (tight enough not to fall off) and slightly tighten. I will be very careful and tighten slowly and wait (patience)

Although the crack looks like it's through the bolt hole, it is not. It's only through the casing and the face plate with 4 bolt holes has no crack.

No drop in rpm or strain on the engine when the bang occured. It only started pumping fluid out of the crack like a waterfall.

Also, no sign of broken metal in pump or gears. Although the gears look like something could have scuffed them. I will post detailed photo's after I get this thing figured out.

Once again, I am greatful for everyones help and sincerely could not have assembled, trouble shooted this tractor with out everyones support.

Regards-

 

[slorne]

Left something out

6) Nothing - So I turned up the RPM's / AND TRIED TO MOVE THE BOOM - and bang

 

[slorne]

All,

Well I am pleased to report the whole issue is fixed. I will do a quick write up with photo's for John to post on BH installation, if he is interested.

Here's a summary of what the problem was:

1) No bh operation was a result of metal shavings in the PV

2) After cleaning the PV, I had the pressure set too high and later found out there were a heck of a lot of metal shavings in the fluid tank and each hydraulic line (bled each line)

3) The other big problem I had was that the bh ships with a pin in the boom to lock it in place
-I did not remove the pin and when I tried the boom (after correcting the pv issue), I think the pin and the high pressure caused the pump to blow

Although this issue took me a week, in my spare time, and cost about $100, I learned the following:

1) Always remove the pin in the bh boom after assembly and before trying operation (I was a dumb ****)

2) I found almost a hand full of metal shavings in the fluid tank, no kidding
-I used a big rubber coated magnet and a two foot flexable piece of spring connected to the magnet (about 1/2 inch thick) to completely clean all the metal shavings out of the tank

It almost seemes like the tank was under a drill press and alot of shavings fell into the tank during manufacturing. Also, make sure to clean the screen filter well as there was metal shavings inside the filter.

Once again, I am greatful to everyone who helped me with this issue.

Thanks Again-

slorne

 

[bluechip]

Be sure to adjust your PR valve, moving the boom with the pin in place should not blow the pump but should hit the PR valve, makes sort of a buzz/screach type noise.

 

[JohnS]

Glad to hear it all worked out. Thanks for letting us know about the pin. I didn't understand when the PV was cranked down, why the rams didn't move. /forums/images/graemlins/wink.gif

 

[mark1]

Hi Just a quick note about the "Storage pin" The pin is great for keeping the boom in position when not in use.BUT DO not slip the pin in the hole of the boom when in use.I looks like a good place to keep it.But it will crush the steel hyd.line on the boom cylinder when using the hoe. This was written up a while back in the NYCTOA site. /forums/images/graemlins/shocked.gif