Hydro

69stang · Dec 25, 2017

I have a IH 656 utility tractor hydro. A few times now when I am backing up the inching pedal does not do anything, still full power. This has not happened in forward. Thinking maybe a check valve somewhere that could be not working properly, or maybe something else. Any advise would be greatly appreciated.

Tracy Brown · Dec 25, 2017

Don't now what to tell you. However, I recently bought a 656 with bad hydro and the mechanic the PO took the tractor to told him if he had brought it in when it first started acting up, it would not have been an expensive fix.

Bob · Dec 25, 2017

LOTS of things involved... Foot-n-inch valve connected to "clutch pedal" (#14) controls drive control valve (15), both in the first diagram, which releases the reverse relief valve (#8) in the "center section" of the hydro shown at the right of the second diagram. NOT sure what all can go wrong, or stick, the troubleshooting chart in a factory service manual would probably help, I'm 24 miles away from my copy as I type this, so I can't offer any more advice at this time!

<img src = "http://cnh-b2b.ptcmanaged.com/index.php/sbsimage/CSIH/default/462663.png">

<img src = "http://cnh-b2b.ptcmanaged.com/index.php/sbsimage/CSIH/default/50513.png">

Jim Naden · Dec 26, 2017

(quoted from post at 18:42:44 12/25/17) I have a IH 656 utility tractor hydro. A few times now when I am backing up the inching pedal does not do anything, still full power. This has not happened in forward. Thinking maybe a check valve somewhere that could be not working properly, or maybe something else. Any advise would be greatly appreciated.

Does it not release the drive pressure every time in reverse or is this an intermittent occurrence?

I assume from your description it never acts up in forward. Is that correct?

I will also advise you to learn to maneuver without using the foot-n-inch valve to modulate the drive pressure. It can score the relief valve if done to excess or under a heavy load.
I hook my little finger around the grab rail and move the S-R lever with my hand. Works smooth for me.

ejr-IA. · Dec 26, 2017

their shims in No. 14 you can take out or in just like adjusting a clutch so it will bypass.

69stang · Dec 26, 2017

It does only happen in reverse so far, and is intermittent.

Why would using the foot pedal score the relief valve?

Jim Naden · Dec 26, 2017

(quoted from post at 18:36:02 12/26/17) It does only happen in reverse so far, and is intermittent.

Why would using the foot pedal score the relief valve?

Depending on the load you're trying to move, position of the S-R lever and other related factors, modulating the movement with the foot-n-inch valve can cause the relief valve to flutter back and forth rapidly and cause scoring. It usually results in a loss of drive pressure because the piston will not always return to it's seated position.

Jim Naden · Dec 26, 2017

(quoted from post at 12:44:20 12/26/17) their shims in No. 14 you can take out or in just like adjusting a clutch so it will bypass.

Shimming the foot-n-inch valve will only effect the maximum drive relief pressure allowed, shouldn't effect modulation characteristics.

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69stang

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