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