Issues with Valmet 415EX with a Risley slingshot head.

[lblack79]

The slingshot head on my 415EX uses a 135cc Linde motor for the disc saw. I'm having issues with the Linde motor blowing the bottom shaft seal. All of my head and carrier pressures are within spec. The machine developed the issue after replacing the main hydraulic pump coupler. I'm not sure if this is merely coincidental. Any input would be greatly appreciated.

[sshier]

Is there any possibility you reversed a couple of hoses had this happen on a slash table years ago it had quick couplers and if the two for the saw got mixed it would blow the shaft seal out just a thought

[lblack79]

It is not possible to mix up the hoses, as the hookups are all stamped and labeled on the saw motor control block.

[gjersy]

Not sure what pump that is but if you have a case drain on it, check the hose for blockage, kink, ect. On my Harvey i blew the seal out of my saw motor just occasionally, and fixed the problem by putting a bigger 3/4" hose from the case drain back to tank. Maybe you have a case drain restriction?

[kiko]

I agree with the others.  Either you have a restricted case drain line or you have excessive internal leakage in the motor which will cause to much volume for the case drain hose to handle and thus putting to much pressure on the shaft seal.

[lblack79]

We have already replaced the case drain hose all the way back to the tank. Also, we sent the motor to Linde for inspection. They say the motor is fine.

[kiko]

Sounds like the obvious stuff has been covered. I am not familiar with the Risley  head.  Is it blowing the seal immediately or do you get some run time between failures.  With the disc saws I am familiar with when the saw is shut off there has to be some sort of relief or check valve to allow pressure relief.  When the saw valve is shut off the momentum of the disk will make the motor into a pump that is deadheaded without  the check valve  or reliefs.  This will blow the seal.  Look for a check valve in the saw circuit and make sure it is operating.

[lblack79]

We'll get some runtime between seal failures. Sometimes an hour sometimes a day. The seal only fails when saw is in a cut. And the saw in not stalling.

[kiko]

If it only fails when in a cut then the motor is leaking pressure to case under load . Even if they checked it.

[bushmechanic]

Kiko is right on. What you could do is a case drain test with the motor cold and then with the motor hot and see what your difference in volume is.