I am an agricultural hedge cutting contractor and having major trouble with the motor that drives the cutting rotor. As i was doing some maintenance work on the rotor i noticed the motor had been slightly weeping so took it to the local hydraulics chap for the seals doing. I have had the third set of seals blow on me yesterday. The last ones he told me had a 9 bar pressure rating?????
Whilst he had the motor in pieces i noticed that one of the 'w' type seals inside had i tiny bit missing on one end. He told me that this would not cause the shaft seals to blow out, is this true??
It is a Ultra gear motor in question. I also wonder if there could be some back pressure on the return side that is causing the seals to blow???
Any help much appreciated!

quote:

Originally posted by pyal440:
I am an agricultural hedge cutting contractor and having major trouble with the motor that drives the cutting rotor. As i was doing some maintenance work on the rotor i noticed the motor had been slightly weeping so took it to the local hydraulics chap for the seals doing. I have had the third set of seals blow on me yesterday. The last ones he told me had a 9 bar pressure rating?????
Whilst he had the motor in pieces i noticed that one of the 'w' type seals inside had i tiny bit missing on one end. He told me that this would not cause the shaft seals to blow out, is this true??
It is a Ultra gear motor in question. I also wonder if there could be some back pressure on the return side that is causing the seals to blow???
Any help much appreciated!

If your motor have a 1/4" hose for the motor case drain, chect that line, if that hose have kinks or other that can restrict oil flow to tank, pressure in casing will build up and blow shaft seal, especially on high rpms and high load, when internal leakage in motor is bigger.
Blowing that seal can also be an indication that motor is worned out (high internal leakage).
Sometimes hoses can collapse inside and cause restriction too. Make sure that hose is intact inside aswell. If you change that hose , you can upgrade to 3/8", especially if it is a long hose, 10-30ft.
Usually designers make case drain go straight to tank, instead of thru filter, to avoid the pressure caused by the return filter.

If there is no case drain, back pressure in return might cause seal to blow. Or there is a fault in the motor. Check return line for kinks and other errors the same way as for drain line.

quote:

I am an agricultural hedge cutting contractor and having major trouble with the motor that drives the cutting rotor. As i was doing some maintenance work on the rotor i noticed the motor had been slightly weeping so took it to the local hydraulics chap for the seals doing. I have had the third set of seals blow on me yesterday. The last ones he told me had a 9 bar pressure rating?????
Whilst he had the motor in pieces i noticed that one of the 'w' type seals inside had i tiny bit missing on one end. He told me that this would not cause the shaft seals to blow out, is this true??

Too much internal leakage, through a worn gear housing or gearset, or thrust block wear or thrust block seals that have enough damage will pop out shaft seals. Is there a snap ring holding the shaft seal in? Are you sure the right seal was installed, not one that was 'close enough'?

quote:

I also wonder if there could be some back pressure on the return side that is causing the seals to blow???

Yep absolutely if there is no case drain line.

Hi,the number of seals Ive run across that "weep" on hydraulic driven motors has usually been worn bearings. Its certainly possible to have internal leakage and a restriction on the return line. If the output shaft has a wear pattern where the new seals seat it will still "weep:,use a speedy sleeve or change the drive shaft-hope that helps-Brett