Fluctuating pressure

gear box should weigh more than the pump it drives

I liked Gear-drive too, 'til they ALL started failing, from wimpy oil seals about 12 years ago..
they seem to be "all better" again, but I still think they'e too expensive compared to the additional options
you get from belt-drive.. especially the "soft-connection" between the shafts, as on belt drive..
As something goes wrong, it doesn't involve a damaged engine-shaft as on direct drive units.
Our service department has gotten rel good at fixing motor-shafts,
but the're not as good as new, and an unnecessary failure.
Long-Term-Low cost equation always comes up this.. belt drive.
and that's from someone who's sold LOTS of direct drive.
If you run 13hp or less, yeah, the gear reductions are fine, now, it seems.
just don't try to run'em over 13hp..
you're pushing luck, and rebuild cost..
They are time-consuming and always more expensive on a bad day.
..until someone comes out with a convincingly beefier version than the ZGR, or the AR..
"claiming" a 25hp rating doesn't convince me..
I need to see "the beef" and actual reliability.
A gear box should weigh more than the pump it drives. Eh?
So far, stick with belt drive.
 
I just like the gear drive setup, but I had to fix an engine shaft on one, found a place after a lot of looking with a mill big enough to fit the engine on and had the keyway cut with a circular blade. How do you guys fix them Jerry? The gears and the bearings look plenty big enough - like they're out of a truck! its the shaft interface thats the weak link - if they could incorporate a flexible coupling somehow it would be perfect. You do get that side load on the pump with the belt. I tack welded the key at the front and back when I put mine back together and I believe that is going to make it last??

Here's a question - I've heard you want a hardened key and that you don't want a hardened key??
 
Tom,
I have a patent-idea on my drawing board for a flexible coupling that would solve ALL the shaft issues,
I just haven't brought it to a pump mfr yet.
Anyway, we fix the shafts by laying into the bad shaft, a frozen shaft key..
we build the metal back up with a wire-feed welder, directing the heat onto the shaft..
being sure to keep a wet rag against the bearing seal.
remove the shaft-key that isn't frozen any more,
put in a new, perfect-sized (as long as will fit) shaft key, and there ya go !
It's easy enough, we generally charge only $39.50 on a loose engine..
and I can't remember the last time we had to replace the oil seal !

About tack-welding the shaft key..
we've done that on EVERY repaired system in our service department,
and on EVERY new system out of the production department,
as a "process proceedure" for the past 25 years.
We don't cut corners on reliability.

The true path to strength, is the elimination of weakness.

I'm such a broken record.. after 53 years aging, 30 years in this business,
survived a divorce, and over 100 employee-relationships,
yep, I talk in metaphors !
 
I just thought tacking the key in seemed like a good idea - so far so good. I put an aluminum key in and welded in around it like your saying and was able to take it out leaving a 'new' keyway, but it didn't last - didn't tack it in that time though. I'm still surprised at the wear, it seems like plenty of area to take the horsepower. So about the hardened key - yes or no?
 
cavitation eats engine shafts !

honestly, we use cheap steel key from Grainger, or Home Depot.
DON'T use aluminum, or you'll find your shafts stuck together like a couple teenagers.
:rotflmao1:

oh yeah, the only reason you have a problem in the first place, is cavitation..
make sure the system has "the perfect water supply":nhl_checking:
next !
 
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