JD 5520 brake loss after hard use. Any ideas?

[JD5210]

When was the last time you changed the hydraulic fluid, filter and cleaned the pickup screen. Since it only happens when things are hot, I wonder if the hydraulic fluid is thinning some and getting pass the o-rings or inlet check valve in the brake value. The following is for the 5X10, but I think it would be the same for the 5x20.

When either brake pedal is pressed, the brake piston is moved to the front, thereby closing inlet check valve, which immediately closes brake valve reservoir. As it travel further, the piston opens pressure equalizing valve, trapping the oil in equalizing passage. The increase in pressure causes outlet check valve to open and the oil is forced under pressure to either brake housing. When both brake pedals are pressed, pressure oil flows through both outlet check valves to the brake housings causing the pistons to open both pressure equalizing valves, and the pressure in both brake cylinders is equalized. The outlet check valves ensure a simultaneous braking effect. The pressure equalizing valves and outlet check valves ensure equal braking.

JDparts
John Deere - Parts Catalog

5X20 operator manual
http://manuals.deere.com/omview/OMRE199128_19/?tM=FR

 

[Tx Jim]

Here's the brake valve parts photo. I have a Kubota M7040 that I bought used with very few hrs that has 16.9 X 30 Firestone's that tear up the soil while turning almost as much as a plow.

 

[sixdogs]

The hydraulic fluid and filter has been changed. I'm not aware of cleaning a pickup screen and don't recall it being mentioned in the owner's manual but I'll look into that. Thank you.

The Kubota 7040 is a great tractor and I wouldn't mind owning one.

 

[jd110]

Does it seem as if the hydraulics/transmission is getting extremely hot? I wonder if your brakes may be dragging and overheating. Try jacking up the rear wheels and put transmission in neutral. the rear wheels should turn very freely. Another thing to look at, the bleeder screws TxJim mentioned has a plastic cap on it. Often when the brakes drag, and get hot, the plastic caps will melt.

 

[Tx Jim]

jd110
I noticed that the later 5000 series tractors such as the 5520,5083E,etc have the same brake springs that the earlier 5000 series tractors but do the brakes have the same history of dragging?
Thanks,Jim

 

[sixdogs]

I'll take a look at the bleeder screws today but I can't imagine the brakes dragging. From searching the comments here, it seems like it has to be either air in the system and bleeder screw related or somehow connected to the brake valve.

If it is air in the line related you would think ir would happen all the time so maybe the valve? Brakes work fine when it's not hot. I think I'm going to have to take it to the dealer. Woe is me.

 

[Zebrafive]

I wonder if there is something heating up the hyd fluid, like an internal leak.

 

[Tx Jim]

I wonder if a hyd control lever isn't returning fully to neutral causing pressure to open a relief valve.

 

[Zebrafive]

I wonder if a hyd control lever isn't returning fully to neutral causing pressure to open a relief valve.

It may not open the RV, but could build up a lot of heat.

 

[sixdogs]

I can't take to the dealer for a couple weeks or longer so as soon as I learn the problem I will advise. Tractor doesn't get used hard that often so it may take a while to figure it out. I think it will be trial and error in that you just have to keep replacing things until you get lucky.