Planetary Gearbox mounting 1

[elinah34]

Hello,

I am trying to understand why the planetary gearbox manufacturer recommends mounting his planetary gearbox through the High Torque (Low Speed) side.
I tried to figure out what is the reason, but unfortunately he didn't reply.

A colleague told me I would better mount the gearbox through the High Torque (Low Speed) side, because otherwise "I will transfer all of the generated forces through the gearbox housing", and I am not sure I understood what he meant.

I tried to use a simplified FBD (Force Body Diagram) to analyze the reactions on the gearbox housing in both optional mounting cases (through the High or Low torque side), and it seems that in both cases the gearbox housing reaction would be the same – tangential friction forces (under the bolts' heads) that resist the same torque, no matter to which side it's connected.
Am I missing something?

Thanks!

 

[drawoh]

I have to point out that as for my design, I guess and hope there won't be any problems because it is only lightly statically loaded (this is a part of a gij that will be used in the manufacturing line).
But it's really important for me to learn about more complex cases, so when I will have to design with gears etc. In such cases, I will be able to know all the considerations.

I am just following rb1957's train of though here.

Most of my design experience has been with optics. In opto-mechanical design, the bone-head move is to mount the optics to a flimsy structure, align the optics, and then mount a rigid cover. A whole bunch of people, especially micro-managers, do not understand that plates are not rigid. This makes four-point bolt-downs, and anti-vibration mounts a whole lot of fun.

If you are designing your own gearbox, your shaft mounts need to be rigid, and protected from the mount faces. This is done either by structurally isolating the gearbox from the mount holes, or more likely by making the whole box stupid strong and rigid. Is isolating the gears from the mount face even possible?

 

[mfgenggear]

"I am trying to understand why the planetary gearbox manufacturer recommends..."
OK. We know what "a colleague" said, and we know what various folks on this fine forum have said. But we don't know what the Application Engineer at the gearbox manufacturer, the folks that actually made it, said. I am assuming we don't know that because you didn't ask. I don't mean checking their website or their catalog. I mean picking up the phone and talking to a live person.

No disrespect intended here, but I get awfully tired of giving this same advice over and over again - call the manufacturer and talk to a live person! Not an order taker in Sales. Talk to a live engineer in Product Design or Application Engineering. Manufacturers hire those people for one reason - to help you use their product successfully, and then come back later and buy another one. There are so many intricate details that could effect that recommendation. You might learn that in your specific application it would be ok to mount it the way you want to. Or you might learn the very good reason NOT to do that. The engineers at the manufacturer know more than anyone on this forum knows about that particular question. Call them.

i agree