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checking hydraulic pumps

clintm455 Join Date: Apr 2007 Posts: 2 Georgia

2007-04-01          140923

I have a JD 2940 I need to know how to check the front hydraulic pump and the transmission pump to determine which one is bad. When the tractor is at idle the pressure is very low but as soon as I rev the motor up to about 1500 rpms its pressure goes up to 2000psi. The steering works great when the tractor is cold but when the oil gets hot it become hard to steer the tractor. The transmission is also not working right becasue of the loss of pressure If you call help me please respond Thanks !!!! Clint Martin

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checking hydraulic pumps

hardwood Join Date: Dec 2002 Posts: 3583 iowa

2007-04-01          140928

Clintm-455; Have you changed the fluid and filters? If they are OK, then I would suspect the front pump. My experience has been tha when a charge pump quits, you get nothing, but when the charge pump is good and the front pump is bad your symptoms sound right on. Best of luck. Frank. ....

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checking hydraulic pumps

clintm455 Join Date: Apr 2007 Posts: 2 Georgia

2007-04-02          140953

Thank for the advice Frank I am going to try this first because it is easy to rebuild the front pump vs breaking the tractor apart If anyone else knows of any more things to check or do please post it Thanks Clint Martin ....

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checking hydraulic pumps

jd110_1963 Join Date: Feb 2002 Posts: 87 westminster, md

2007-04-02          140956

Clint, the front pump will not affect your transmission. It sounds to me like you have something wrong with the charge circuit. There are many things here that can cause problems. The easiest to check is the filter relief valve. I assume you have already changed the filter. Also you should drain the oil and remove the sump screen to see if it is clean. There can be brake material or other debris clogging the screen. After you are sure the screen is clean and the filter is changed, remove the relief valve. It is located just above the transmission filter and it screws into the side of the case. you will need a 1 1/4" wrench or socket to remove. After the plug is removed, reach into the bore with a needle nose pliers to pull out the cartridge valve. The image in the link shows the valve. Items # 10 & 11 are contained inside of #12. They are held in place with the #15 roll pins. If either one of the pins are broken or if there is debris stuck in the slot in #12, this can cause the problems you are having. If all these things check out, then you probably have an internal problem such as a worn transmission pump, broken oil tube or a leak in the HI-LO clutch or PTO clutch. All of which requires splitting the tractor to get to it. Good luck! ....


Link:   2940 parts catalog

 
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