Cat 299D2 XHP Blowing hydraulic hoses. Bad relief valve?

[92U 3406]

Hoses rubbing through where they pass through the frame is such a common issue on the Cat machines its not even funny. I would make a point of armoring each hose whenever I had to pull one of the guards off the frame. Even with only a few hundred hours on the machine it was almost a certainty to find a hose that already had braid showing.

Just a very poor design IMO.

 

[Tree Mulcher]

I think the parking brake release circuit runs on charge pump pressure <550 psi

 

[mjones35]

Just wanted to follow up on the final (I hope) resolution on this problem. I installed the new hoses, so now all three hoses are new: the hose from the pump to the T and both hoses from the T to the left and right drive. I also temporarily installed another T and a hose that is attached to a pressure gauge outside the cab. I monitored the pressure for a couple hours of use and the pressure was always around 500 psi when the parking brake was released. It was interesting to see that the pressure drops to zero and the parking brake is engaged automatically every time the machine stops moving for more than a couple seconds. The brake is released and the pressure goes back to 500 psi immediately when you start moving.

I still don't understand how both hoses from the T to the left and right drive could blow within hours of each other. One hose was blown in a spot out in the open that didn't appear to even be touching anything. The other hose was clearly worn where it goes through the cover plate. I'll just have to assume that the problem is fixed, but I'll periodically check all of the hoses going to the drives based on the advice posted by others on this thread. I appreciate all of the help and info.

 

[f311fr1]

On our 299D2 we wrapped the the hoses with a rubber backed carpet tile and punched holes in six spots to lace together with zip ties. Never had another issue with this.