Volvo EC210BNLC Swing brake activation during swing problem

Hi all,

I have EC210BNLC model 2006 year SN:*EC210V20549*
Problem is that swing brake comes on sporadically during swing. Sometimes 20 times a day, sometimes once in 3 days. I have very blurred schematic diagram for this excavator. Can anyone share if they had this kind of a problerm or hydraulic schematic that shows swing brake connections? From what I can see, there is no electrical solenoids involved in the circuit, all pure hydraulics. Brake lines pass thorough few block, but my resolution is too blurred to see what they actually are.

Thanks all!!!

Good day
Please see attached if the pilot pressure is good comes down to piton seals or timer valve fault.
Kind regards
Uffex

Here's just a little more on what Uffex has shared with a more detailed show of the slew motor. The brake release is supplied by oil that gets the motor turning from either direction. I would spin down the case drain filter and inspect for debris.

Thanks for the advice !!!! Uffex thanks for the diagram, now I can see what is what!!! My plan is to check release pressures, and if seals are leaking. If oil is leaking in the reductor area, dip stick should show it full of oil. If it's leaking in the return....well that will be a bit harder to diagnose.
funwithfuel, there is no file attached, if there was supposed to be one

How about now?

Btw can anyone explain what a timer valve is in this system?

It's easier to think of it as a delayed apply. It holds pressure after swing is stopped allowing the anti-cavitation/ hydrodynamic braking time to work before applying physical friction disc brakes. This keeps your brakes from applying during swing.

Ah ok. That's the flow restriction with one way valve in parallel with it? I never knew it is called timer valve.

It depends on manufacturer. Everyone has their own name for it. Delayed apply, timer , applied decay. Same animal.
Volvo applies this to the swing, less moving parts, simpler installation, less likelihood of applying brake while in swing.