Woods backhoe problems

[kennyd]

80cj, You wrote:

they said they had tested all the pressures (at the bh cylinders), but he asked them to do it again. we also found out that when they measured the back pressure, they didnt use a 'T', just a dead-headed leg. that was disheartening. after hearing that, i just want my tractor back and i will do it myself.

Not quite sure what you mean by "back-pressure", but deadheading a line directly into a pressure gauge to test the PRV (pressure relief valve) pressure is an acceptable practice and will do not harm in short bursts. Even if you use a Tee, you still need to stroke the cylinder to the stop to deadhead the pump to get a reading.

they never did measure the back pressure. i asked them to try to get the wood's rep to come out and look at it. so the dealer said he will call him today.

Agian, not sure what you mean by "back pressure"

It sounds to me like there is a PRV somewhere that you are missing? I don't understand 2200 at the FEL and 1800 at the backhoe.

 

[80cj]

by back-pressure, i mean the return side. if you have 2000psi on one side of the cylinder, but have restrictions in the return side so that you have 500psi on the other side of the cylinder you will not have good performance.

deadheading is ok to test the relief valve, but it does not tell you anything about the pump performance under load. you need a T for that. they dead headed the line and read the pressure. then moved the lever the other way to read what the return pressure was. it was 0 becuase they would have pulled a vacuum since it was dead headed.

thanks
shawn

 

[wedge40]

I'm no expert and I'll be curious if I'm right. I would say the BH spool has a bad PRV. Also from what I've always been told, you wont get accurate measurements by using a T, you should dead end into the gauge.

Wedge

 

[80cj]

i dont believe it is the relief valve. you have to measure the pressure on the return (to tank) side with a 'T'. if you dead-head it, there won't be any flow and the pressure will just drop to 0. (it may pull a vacuum)

thanks
shawn

 

[80cj]

interesting update on my tractor, recall that it has been at the dealership for 5 weeks now, and this is the 3rd trip and 2nd dealer that i have taken it to to correct the problem in the last year.

after taking another day off work to go 'help' the dealer work on my tractor, i notice that the assembly instructions from woods have changed. it turns out that they changed them to use some sort of manifold block about a month or so after i bought my backhoe, but somehow nobody caught it. woods still has the old version on their website, but internally is working to the new version. ofcourse everyone is sick of me and continue to tell me to 'just let them do their job', but if everyone would have, i believe i wouldnt still be dealing with this. to woods credit, they are covering this under warranty.

my current theory is that it is a compound problem. the tractor pump is rated for ~8 gpm and the bh is spec'd for 4-6 gpm. the 1st day i had it i probably ran it for 10 or so hours straight. i could smell the hydraulic fluid, but they told me that was normal b/c a hose had broken during transport and it was just residual fluid. so since it is a constant displacement pump that relies on the relief valve to regulate pressure but the rv was sized for 4-6 gpm, it would build up excessive heat. and then i beileve the heat (or some other effect) damaged some seals on the bh.

that is just my theory, but i guess we will just have to wait and see.

thanks
shawn

 

[J_J]

Just don't run the tractor at high rpm, less GPM's. You will probably have better control on all the BH functions.

 

[80cj]

i had been running it at about 1500 rpm. when i ran it faster, it got hot faster (i could smell it) and it was very jerky to use. but they said that was part of the problem and that i was to be running it at 2500 rpm. i really believe that there is internal damage, maybe in the valve body.

thanks
shawn

 

[Mousefield]

Sorry to hear you (your dealers) have not been able to solve the problem. Must be getting pretty frustrating by now. Just to let you know I normally operate my Woods BH-7X backhoe at around 1,700 - 1,800 RPM.

 

[80cj]

i can't express how frustrated i am. but i'm running out of people to b!#ch at!

thanks
shawn

 

[80cj]

tell me if this seems wrong.

we T'd in gauges at both ends of a cylinder. when the cylinder bottomed out, it had 2000 psi on the press side (that makes sense), but on the other side, when the valve was open there was 125 psi, and if you closed it fast it would lock 700 or 800 psi on the cylinder. so you have 2000 on one side and 800 psi on the other. the woods guy assured me that was normal, but the more i think about it, the more i think that it cant be. i think that explains why i cant pick anything up with the thumb. as soon as i let the valve return, it loses all of its grip strength.

anyone else think this is wrong?

thanks
shawn