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Kubota B7100HST works backwards

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smoulton
Join Date: Nov 2005
Posts: 2 Hondo, Texas
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2005-11-14          119341


After sitting idle and partly disassembled for several years I got my tractor running again, but when I press the "forward" (toe) pedal it goes backwards. When I press the "reverse" (heel) pedal it goes forward. After many hours, I still can't find the problem. Today I drove it three miles, and it cut out a few times. Just stopped, neither pedal did anything for a few minutes, then I could take off and go again. Is there something I can repair or replace? Do I need to have the hydraulic motor rebuilt? Any clues will be appreciated.



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Kubota B7100HST works backwards

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Art White
Join Date: Jan 2000
Posts: 6898 Waterville New York
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2005-11-15          119366


I've never heard of a problem like yours. I'd have to say that it would be a problem in a valve for direction beyond the foot controller. Might just be a piece of dirt but you could be in for a nasty ride if it straighten itself out while driving. ....


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Kubota B7100HST works backwards

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Iowafun
Join Date: Jul 2004
Posts: 955 Central Iowa
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2005-11-15          119370


I'm no expert on Kubotas, but typically on hydraulics, this would be cause to trace out the hydraulic lines and see if if two have been switched. Or if the pedal was installed backwards, etc. ....


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Kubota B7100HST works backwards

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beagle
Join Date: Jan 2004
Posts: 1333 Michigan
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2005-11-15          119381


I'm guessing you may have two problems. The directional problem has to do with the linkage set up between the pedal and the hydrostat. Somehow you are actuating the valve backwards. The cutout is probably the charge pump not keeping up with the motor. There are two pumps in the hydrostat, the variable pump that drives the motor, and a charge pump that is only there to replace the losses in the closed loop. If the charge pump doesn't keep up, the system looses pressure, eventually, until the charge pump can catch back up. That's why if you wait long enough, the charge pump rebuilds the closed system pressure and you off again.

This doesn't necessarily mean the charge pump is bad, although it could. Anything that restricts flow to charge pump could also cause the problem. Make sure that not only are the filters clear, but there is a sediment screen in the system that should be cleaned with low pressure air. If your screen is plugged, you could starve the charge pump of fluid.

Also make sure there is enough oil in the system, or not too much. An overfull reservoir is harmful since the exhaust fluid is being sent into the reservoir oil, which can cause foaming of the oil, and lead to a lot of trapped air. ....


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Kubota B7100HST works backwards

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smoulton
Join Date: Nov 2005
Posts: 2 Hondo, Texas
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster

2005-11-16          119445


Thank you for the info. I'll hunt for a filter on the inlet side of the charge pump. As far as the linkage and valve action goes, I've pretty well convinced myself that it is impossible to install wrong... But maybe that sort of thinking is part of the problem. I've got it in for new tires now, and when I get it back I'll replace the hydraulic fluid I used for break-in and clean all the filters I can find and give it another try.

....


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