john deere 4520 hydraulic pump failure

[jf1030]

This is a jd4520 3 years old and two pump failures, it has a e-hydro transmission. Both pumps have failed while pulling and top dressing athletic fields with a turf tiger top dresser. top dresser runs on hydraulics off remote ports. specs on top dersser are 7.5 gals a min. and 35 hp. tractor. salesman say no problem with specs. mechanics say top dresser over heating fluid and causing failures. they say ports are not for continues use. top dresser empties in under 5 min at 2500 rpm. they want to install a power beyond valve to prevent future failures. Anyone have any thoughts or suggestions on this ?

 

[J_J]

If it is a hyd motor that drives the dresser, and running at max load, the pressure will be up around max and will heat up the fluid.

You might consider a hyd cooler in the return line.

You can test the heat areas with a temp gun.

I am not understanding about the PB valve.

The remotes should have a PB port to feed the 3pt.

Could your dresser valve be running in relief?

Pump flow: 12 gpm

 

[oldnslo]

Is this the model 4300? If yes I see that it has at least flow controls built-in for regulating feed rate of material. I would suggest checking what the system pressure is while operating this machine. It is possible that you are running close to the system relief pressure whch can overheat your hydraulic fluid quickly. If only 7.5 GPM are required then 4 GPM is excess flow and is just creating heat in your system with no work being done.