Insane Hydraulics
Bold and audacious blog about fluid power
I received this gear motor last Friday. It came from a verge shredder implement, and what I found really interesting was the malfunction description, given by the operator. He told me me that the motor was working OK, and that the only problem was an oil leak in the shaft seal area. He did admit that the front flange was "slightly worn", however, he was sure a new flange would fix it for good. He told me that they tried to replace the shaft seal several times, but unfortunately, the new seals would not last, for some reason. He also told me that the motor worked in this condition for the last three campaigns!
Let's have a look, shall we?
The first thing that pops out is the spline coupling that has has a nice crack in it, and the front flange, that... well.. has a good percentage of it missing because whatever it is that's attached to the shaft has "ground away" the pilot boss completely!
Since there was no more housing to "house" the stopping ring to hold the seal in place, an obvious fix was a nice set of shims, carefully placed between the rotating spline coupling and the shaft seal to keep it from popping out. Very clever!
The shaft key was sheared. Yes, you read this right - there was essentially no shaft key. The marks on the key stump suggest that the spline coupling was rotating in relation to the shaft. My guess is that the toque transmission between them was secured by the "friction weld" regime.
With all the shenanigans going on at the shaft end, the front bushing was no more, which was no surprise. The shaft seal area on the main shaft was gone, too, and the gears had severe wear as well. One phrase summed it all up with precision - "scrap metal".
Now, I want to say what I can and can not understand.
I can understand the wear - something got loose somewhere and pulverized the flange - these things happen.
I can understand the shim fix and even the cracked coupling - you are in the middle of your first campaign with a second-hand rig, there is no money around and you are on a tight schedule, so you have to make it work till the end of the contract no matter what. I do get these situations - I've repaired scrap with another scrap enough times to know this.
What I can't understand is the "three campaigns" bit. This is beyond me. I can accept all the mechanical ugliness of the quick fix and even more - but only for a single time! You can't run a production piece of equipment (i.e. the equipment that is destined to make money) like that! Especially if you take into account the fact that such a motor is relatively inexpensive.
You can get home on a flat tire. Hell, you can even get home on a rim, if you have to. But when you get there, you replace it with a new one. You don't just "let it be" and drive to work the next day to wonder why your car suddenly stopped going!