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JD 8440 - No movement or hydraulics - possible 2 speed?

W

weseggs

New User
I have a JD 8440, been running well for years. I was on my way back to the shed yesterday in C4, motor laboured a bit as I went up a hill. I shifted to C3 and there was a bit of a thud then I lost all motion forward. I still had steering, brakes, etc.
I put the machine in park and had a look, not leaks, etc. Engine was running fine. I still had brakes, steering.

I shut the machine down but now when I start it I dont have any hydraulics, no steering, no movement. Starts and engine runs fine.

I do note that the top shaft (out of the 2 speed) in the center of the 8440 is not really spinning like it normally would at idle. It normally spins really fast but not it would be doing around 10-20 rpm.
The 2 speed was always a bit grumbly
 
I'd start by checking the transmission screen near the filter housing for debris. Sounds like oil is not moving freely to the front pump. Then check to see if transfer pump in transmission is working by a pressure test. Then make sure the front pump is working properly. When the main pump failed on my 8430 everything stopped working and the aluminum coupler broke. At that point the pump was junk so no rebuild possible.
 
It seems that you have lost clutch oil pressure, which also feeds the front pump, the clutch oil pump is behind the oil filter housing in the left front hinge area, the pump has a drive shaft with a key in it,,it is a 2 stage pump, one for clutch oil, the other to pump oil out of the clutch housing,, the rear pump,,under the rockshaft.. is only for transmission lube. I would start looking there..
 

Possibly broke something in the planetary 2-speed based on how the failure happened causing a big leak of clutch operating oil (and main pump charge oil) "to sump"?
 
Thanks, I'll start with the 2 speed and the clutch pump. Seems like I need to have a good look in there. Sounds like a fun job
 


I had that happen to a Ford once. It was the hydraulic pump. As others have said start with a pressure test because that is quick and easy and nearly definitive.
 
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