JD4700 Hydrostatic Rear Wheels No Power

[pubwvj]

I have a ten year old John Deere 4700 tractor (2001) hydrostatic transmission.
In 4WD the front wheels are powered but not the back wheels.
In 2WD I get neither front nor rear turning.
I get the same results in A, B and C ranges.
All the other hydraulics seem to be working fine (loader, backhoe).
I had gotten low on hydrostatic transmission fluid and I have refilled it. (I always using official JD fluid.)

Observing the various levers under the tractor which control it as my son shifts them I don't see anything obviously wrong. Everything sounds normal.

Any ideas on what might be the problem and what to do to fix it?

Many thanks,

-Walter
Sugar Mountain Farm
in Vermont

 

[jd110]

Sounds like you have a problem with rear differential or final drive. Have you tried engaging the differential lock to see if it will drive with that enagaged? How about pressing on left and right brakes individually while trying to drive? Do you hear any unusual noises while trying to drive in 2wd? Possibilities include sheared off pinion, sheared off bolts attaching ring gear to the differential carrier, or broken left or right pinion stub shaft in final drive. Report back what you find, but bottom line is I think you will need to remove left final drive/axle housing and maybe differential to find the problem.

Oh yeah, welcome to the forum!

 

[pubwvj]

Sounds like you have a problem with rear differential or final drive. Have you tried engaging the differential lock to see if it will drive with that enagaged? How about pressing on left and right brakes individually while trying to drive? Do you hear any unusual noises while trying to drive in 2wd?

Everything sounds normal and there was no bang, pop, grinding or other strange sounds. When I lost the rear wheel power I simply noticed I wasn't able to backup the hill. Front wheels were spinning but no motion on the rear wheels.

I have experimented with both the breaks and the differential lock but no joy. The levers appear to be working. Doesn't feel odd, but no power to the rear.

 

[jd110]

I believe you either have a sheared shaft #3 or 19 in diagram. If one of those is broken, using differential lock would make it drive, assuming the differential lock works. Also could possibly have bolts broken or backed out of ring gear #2 or broken pinion shaft #2. Spider gear shaft #11 could have fallen out also. Pin #21 holds the shaft in.