No breather on 72" mmm gear box

[Lawnjocky]

No breather on 72\" mmm gear box

I just noticed the belly mower that came on my 3520 is lacking a breather for the gearbox. This concerns me. The previous 72" belly mowers I used had breathers.
Several years ago I sold a JD to my brother with a 60" deck that didn't have a breather. He got it hot at some point and it blew the drive shaft seal out, which in turn allowed his oil to leak out. Thanks to his not checking thing's, scratch one gearbox and several hundred dollars.
While I do perform regular inspections on my equipment, I would feel safer installing a breather.
Does anyone think I shouldn't? If so, why not?

 

[fargo]

Re: No breather on 72\" mmm gear box

Help me out, what is a breather ?

I took my 72mmm off for the first time a few days ago and found that there is not much room in the area of the pto. The yokes which attach the mower to the frame have a pin in them and the pin (not the yoke) is very lightly touching the mower shaft which attaches to the pto. There is a very light scratch on the shaft. I've looked at things and it just seems that they didn't make much room between the two. Am I missing something here ? Has anyone else noticed this ?

 

[Lawnjocky]

Re: No breather on 72\" mmm gear box

fargo,
JD's discription ( part name) of a breather is "pressure relief fitting". The purpose is to act as a vent for the crankcase, differential, gearbox, etc.. so that as it is used and build's up heat from friction the resulting pressure can be relieved. Those gearboxes get hot. If you want proof just touch you gearbox after mowing. PLEASE BE CAREFUL, as it will be hot. Also have the tractor off, brake set, mower down, etc.. If there is no vent that pressure just builds up. During a small amount of mowing I doubt there is any trouble. But if you mow a lot at one time, what's going to happen?
As for your second question. I know things are tight, but I will need to look at what you're talking about.
Lawn