Hydraulic motor help needed

[ernemats]

I bought a used flail mower for my 422 and the hydraulic motor for it is leaking at the shaft. The rubber seal around the shaft is worn through in one place. It looks like the seal is held in by a snap ring. The question is can the seal be replaced by just taking the snap ring off and replacing the rubber seal or does the whole motor need to be taken apart? The motor is a Parker the numbers are 00/4, MZG2AB113S1 Made in Italy.. Pictures attached.

 

[PTWannaHave]

Assuming there's a bearing holding the shaft just behind the seal, I would think that you should be able to rip out the bad seal (write numbers or take measurements beforehand) and install a new one that is held in with a press fit...

Someone else with more experience with hydraulic motors should be able to confirm or deny.

Cheers,

 

[KMA]

Here's a pdf with more details on the MZG2A motor:

http://www.mytractorforum.com/attachment.php?attachmentid=240191&d=1355415898

You should at least be able to decipher the part number using the last page.

 

[KentT]

According to what I just learned from a heavy-equipment repairman, when leaking at the shaft seal, it usually means there's a deeper problem inside the motor, such as worn bearings or shaft that let the shaft move around, wearing out an internal high-pressure O-ring type of seal. The shaft seal is more of a "dust seal" not a high-pressure seal. The high internal pressures should be stopped before ever reaching the shaft seal.

IMO, just replacing the shaft seal is a Band-Aid, and likely would not last very long. For a more permanent solution, the motor needs rebuilt, with the shaft and bearings checked for tolerances and wear, and all seals replaced. At least that's what I was told, as I wait for one of my upgraded wheel motors to get totally rebuilt...

 

[ponytug]

What KentT said, x2.

Absent external trauma, e.g. physical intrusion, (stick, nail, etc.), this is great advice.

The bearings, and rotors, keep the axle tightly aligned. So, if you are seeing wear on the outside, there are probably major issues on the inside.

There is not much upside (none?) to delaying a rebuild. If the motor starts shed metal particles, you don't want those circulating to other pumps/motors.

All the best,

Peter

According to what I just learned from a heavy-equipment repairman, when leaking at the shaft seal, it usually means there's a deeper problem inside the motor, such as worn bearings or shaft that let the shaft move around, wearing out an internal high-pressure O-ring type of seal. The shaft seal is more of a "dust seal" not a high-pressure seal. The high internal pressures should be stopped before ever reaching the shaft seal.

IMO, just replacing the shaft seal is a Band-Aid, and likely would not last very long. For a more permanent solution, the motor needs rebuilt, with the shaft and bearings checked for tolerances and wear, and all seals replaced. At least that's what I was told, as I wait for one of my upgraded wheel motors to get totally rebuilt...

 

[/pine]

According to what I just learned from a heavy-equipment repairman, when leaking at the shaft seal, it usually means there's a deeper problem inside the motor, such as worn bearings or shaft that let the shaft move around, wearing out an internal high-pressure O-ring type of seal. The shaft seal is more of a "dust seal" not a high-pressure seal. The high internal pressures should be stopped before ever reaching the shaft seal.

IMO, just replacing the shaft seal is a Band-Aid, and likely would not last very long. For a more permanent solution, the motor needs rebuilt, with the shaft and bearings checked for tolerances and wear, and all seals replaced. At least that's what I was told, as I wait for one of my upgraded wheel motors to get totally rebuilt...

another possibility...
In the same respect whatever the shaft was attached to (externally) could also have been out of alignment/balance etc. and also caused the seal to wear...in a case like this scenario the longer it went unaddressed the bigger the chance that more than just the seal has also worn...

 

[KMA]

Just rebuilt a motor on my PT... it's easy if you can find the rebuild kit for that model. Good luck!

 

[ernemats]

Just rebuilt a motor on my PT... it's easy if you can find the rebuild kit for that model. Good luck!

Just heard back from local hydraulic shop. The motor I have was manufactured before the year 2002 and is no longer made. Am going to take it to the local shop and they will see if they can get a matching seal. Everything looks good and seems tight, it looks like something rubbed the seal .

 

[ernemats]

Just got back from repair shop the motor looks good just needs new seals. Bad news the motor is designed to need a case drain which the case drain outlet had a plug in it. They said it will keep blowing the seal unless it has a return hose put on it. SO I DON'T KNOW WHAT TO DO NOW. How hard would it be to put a return port on to a pt 422 system or would it work on my pt 1845 which has a place to hook up a case drain?

 

[woodlandfarms]

IMO, not knowing your machine, not hard at all. You really need to find a low pressure return line and use it. Lots of them on my PT. Or you could drill a new hole in the tank and just pipe it in.

 

[PTWannaHave]

Is a new motor not requiring a case drain an option...? I would price it out before committing to repairing and modifying the used one.

Seems like that motor was not original equipment for that used flail mower...

Ciao,

 

[ernemats]

The flail mower probably was one that was used on a farm tractor powered by a pto shaft. It was just modified to use on a power trac powered by a hydraulic motor. I don't know what specifications I should look for for a new motor, (size, rpm's, etc.) I talked to Terry at Power Trac last evening and he is to get back to me about hooking up a case drain.

 

[J_J]

A case drain is nothing more than a return to tank.

My PTO flail mower has a case drain hose and plugs in to a 1/4 in QD and all my wheel motors case drain connect to a manifold, and then go to radiator to tank.

My tram pump also has a case drain.

 

[ponytug]

Sorry to hear that you are experiencing a little more than you thought you were getting in for.

By way of background, case drains allow the motor to weep oil internally, and so give the motor a little more cooling, and can help sweep debris out of the motor. A case drain also enables internal seals not to be as rigid. I am not sure what it does for motor efficiency, but it does help motor longevity, tolerance to debris in the oil, and tolerance to shock.
1)

• You do need to hook up the case drain.
• It is pretty simple: just a small (1/4") low flow return line to the tank.
• Optimally, the return line is separate from the motor return line. i.e. not the PTO hydraulic line. (No back pressure on the motor.)

My 1445 has a separate return to tank line; I don't know about yours. (perhaps just diesel PTs?) Assuming not, my bet is that there is a manifold on your front wall that aggregates the returns from your lift arms and the curl cylinder that you could "Tee" into to feed the case drain into.

Congratulations on the flail mower though! Keep us informed on what you decide to do.

All the best,

Peter

 

[ernemats]

I talked to Terry at Power trac and talked to their engineer. Terry said to drill a 1/8 inch hole in the return line hose end and put a 1/8 npt fitting in, then run a 1/4 inch hose from the case drain to the drilled hole in the return line. He showed me that is what they do on their small boom mowers with case drain.

 

[KentT]

What KentT said, x2.

Absent external trauma, e.g. physical intrusion, (stick, nail, etc.), this is great advice.

The bearings, and rotors, keep the axle tightly aligned. So, if you are seeing wear on the outside, there are probably major issues on the inside.

There is not much upside (none?) to delaying a rebuild. If the motor starts shed metal particles, you don't want those circulating to other pumps/motors.

All the best,

Peter

Just a follow-up. The first wheelmotor I had rebuilt was caused by the spring clip that holds the outer shaft roller bearing breaking (into 5 pieces), allowing the bearing to move and pressure to get to the dust seal. When they opened it up, the individual bearings fell out. Replaced bearing and retaining clip, and all the seals. I already had and provided the seal kit. The new bearing, retaining clip, and labor was $85.

Just swapped it on to the PT, and did some mowing yesterday. All is good. Now, I'm going to take the second failed one and have it rebuilt the same way, to have a spare on hand. (I have a seal kit for it also.) The dust seal on it was pushed out so far that I can see the broken retaining clip inside....