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Worm and Wheel Gearbox Design Questions

Doug W

Hot Rolled
Joined
Sep 22, 2003
Location
Pacific NW
So I have a 2hp Grove right angle gear reducer, worm and wheel type that I am using for a project.
The output shaft needed to be reduced for my applications so I tore it apart to replace anything, bearings, seals, etc, that needed replacing.

The design uses a straight output shaft where the 2 tapered roller bearings and worm are simply press fitted. There is no shoulder, snap ring, cross pin, set screw or anything else to keep the shaft from walking out.
I know that there should be no axial force from a pulley, but still I find it odd.

Is this typical on lower power rated gearboxes?

There are 2 steel collar spacers for setting bearing preload, they fit loosely on the shaft. I am thinking of making another, a press fit and drilling and reaming for a tapered pin.
Or just make another shaft with a shoulder on it.

Other issue is the bearing caps use 0.010" thick gasket material. Seems to be unobtainable without buying yards and the 'ask for a quote' routine.
Thinking about reducing the spacer heights 0.010" each, deleting the gaskets and using RTV to achieve proper preload.

Any thoughts?
 

specfab

Titanium
Joined
May 28, 2005
Location
AZ
I can't say it's typical for this sort of thing, but I think most applications (including the one I just was involved with) rely on the other parts of the system to be fixed, and the gearbox gets bolted to its mounting, so "nothing moves".

Note that Grove Gear has a little note included with the physical gearbox that suddenly makes you aware that if you are running the gearbox at lower speeds, i.e., a few hundred RPM instead of rated 1200 RPM, you NEEDED to let them know when you ordered the gearbox, so that they can MODIFY the construction.;-) We just went through that little exercise, and apparently the modification consists of -- more oil. If you have the box in a worm-over position, I guess there isn't enough agitation of the oil bath to keep sufficient oil on the worm, so filling the gearbox to bathe the worm is required.
 

Doug W

Hot Rolled
Joined
Sep 22, 2003
Location
Pacific NW
Yes the gearbox is bolted in place, and the pulley, wheel or sprocket is bolted to the output shaft, but there is nothing other than press fits to keep the output shaft from walking around.


I saw looking into Grove's info I saw that over worm type at low speeds or odd angles require more oil.
Luckily mine is under worm type.
 

specfab

Titanium
Joined
May 28, 2005
Location
AZ
Yeah, we only had the catalog page that was sent to us (by Grove/Rexnord) that showed the drop-in replacement we needed for the machine. No mention of the small details like extra oil mods. The oil is of course one of those that everyone stopped selling in quarts (except Grove, of course). Since I didn't want to buy a 5-gallon pail for $460, I ended up paying Grove $160 for a quart. Not sure of the economy there...

They might be able to supply you with the bespoke gaskets for your gearbox, too. If I were deep into it as you seem to be, I'd probably go with the RTV solution as well, though.
 

magneticanomaly

Titanium
Joined
Mar 22, 2007
Location
On Elk Mountain, West Virginia, USA
I would definitlely want to see some positive way to keep the shaft from walking out. Can you get a parts drawing to see what might be missing?

On the gaskets, a lot of back-to-back tapered roller bearing setups use shim packs to set clearance/preload, in place of a gasket.
 

Doug W

Hot Rolled
Joined
Sep 22, 2003
Location
Pacific NW
Never underestimate the power of Loc-Tite!

Yes I will be using it if I don't just make another shaft. Didn't see any sign of it on disassembly and inspection.

I would definitlely want to see some positive way to keep the shaft from walking out. Can you get a parts drawing to see what might be missing?

There is nothing missing, the shaft, bearing spacers, worm gear, bearings simply don't have any snap ring groove, hole or any other positive method of keeping the shaft in place.
Interference fit it only.
 

cudafamily

Aluminum
Joined
Oct 31, 2013
Location
Evansville, IN
I would stay away from drilling and installing a taper pin. Sounds like you would be creating a point of failure in the near future, unless there are no loads on the shaft.
 








 
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