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Jd 400 Will Not Move

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#16 Gary400 OFFLINE  



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Posted June 04, 2012 - 05:47 AM

there is no release valve on the 400 it has a neutral so you can push it around .

#17 olcowhand OFFLINE  


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Posted June 04, 2012 - 07:32 AM

there is no release valve on the 400 it has a neutral so you can push it around .

That's what I figured, as most units with a neutral don't have a release valve, such as the Massey 50 & 55 series, and also the MTD 990 series.




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Posted June 04, 2012 - 10:27 AM

That's what I sorta figured from my inline Sundstrand. I wasn't sure about the "U" version.

The basic anylisis holds true though. The relief valves should pop before a healthy engine does more than bog a little bit.

Either some pressure checks on the hydro or splitting the hydro from the rear end are next. I'd split the hydro from the rear end to isolate the problem after checking all relief valves, brake function, and the neutral function of the high/low shifter. Relief valves invariably fail in the open position unless something is holding them closed and a lockup in both directions indicates that the motor is not turning because it has failed or there is a mechanical problem in the rear end.

If the neutral function allows hand pushing the tractor in both directions, then 75% of the rear end is fine. The 25% left consists of the miter gear and primary reduction, which includes the parking brake shaft.

If the relief valves are not opening and the motor does not turn the rear end, the system is hydraulically locked and that will kill the engine, not lug it down. Another indication of a locked brake in combination with relief valve issues.

Edited by TUDOR, June 04, 2012 - 10:33 AM.

  • MH81 said thank you