Looking for gearboxes designed for large overhung load

[jdunfee12]

I am designing a mechanism which needs to rotate a relatively large overhung load. I don't know if what I am seeking is out of the ordinary, or perhaps I am just lost in all the hits from my internet searches. My own experience in this area is limited. The system will grab and rotate insulated panels. These are not especially heavy, but are fairly large. Up to 4ft wide, by 30ft long.

My system will be hydraulically powered, and I did receive a recommendation for a hydraulic motor that does not need any gear reduction, the Helac Rotary Actuator L30 series. They have models that can easily handle my specs. But, that will be close to $5,000, so I am trying to cut costs. A smaller hydraulic motor coupled with a gearbox, would seem to be a much cheaper solution. But, the overhung load may be a barrier to that. Of course, I know I can add a bearing, but am hoping for a simpler design if possible.

Here are some approximate specs for what the gearbox will see;

4 RPM output
6:1 reduction.
Output torque; 20,000 in-lbs
Overhung Load; 10,000 in-lbs

Can someone suggest a source to search for a gearbox to handle this?

Thank you for any suggestions or comments,
-joe

 

[MikeHalloran]

Consider a couple of pillow blocks supporting a big-ass jackshaft.
Drive it with whatever you want.


Mike Halloran
Pembroke Pines, FL, USA

 

[desertfox]

Try these people

http://www.sew-eurodrive.co.uk/produkt/gear-units-gearmotors.htm

 

[jdunfee12]

Thanks for the recommendations. I have just now contacted the Eurodrive folks.

Of course, the pillowblock is the standard approach. But, if an existing gearbox meets our needs, it simplifies the design and assembly, and may even be cheaper.

Thank you,
-Joe

 

[geesamand]

Mike's approach certainly works - isolate the gearbox from the overhung loads.

Mixer drives will work, if the output shaft is vertical.

SEW Eurodrive has many options that can be bolstered for overhung output loads but some sizes/models may require more frequent maintenance teardowns than you prefer. (Read the IOM's and see if it contains sealed-for-life bearings that are supposed to be replaced annually)

What rotational accuracy do you need in positioning these panels? Keep in mind that a power transmission gearbox will have a level of backlash, and over more than one reduction, that backlash will multiply.

David

 

[jdunfee12]

The shaft will be horizontal.

The device will be attached to a forklift, and rotation will be controlled by the operator using the hydraulic valve on his forklift. I actually want a fair amount of play in the positioning. I will add some item to the gripper assembly to insure at least a few degrees of movement, so that when the panel is put in place, the operator does not have to be as accurate.

Since this device will only be used a few days out of a month, I suspect maintenance will not be an issue.

Thank you all for the very valuable comments.

-Joe

 

[BrianE22]

It might be more expensive than the other ideas but it's simple: Use an over-sized gearbox.

 

[geesamand]

Hanging off a forklift, I'm not picturing any kind of assembly with a long shaft generating major bending moment. (If it did, I would need to visualize how the forklift will avoid tipping over sideways). I'm picturing a short shaft now with significant side load on the output shaft bearings.

This is very common - if it's not the source of load, in many cases the side load might be a chain drive, belt drive, or other power transmission element that produces side load. So a huge number of commercial gearbox products will support this kind of load if you can quantify it and express it to them. Even electric motors handle a fair amount of side load, and can be upgraded to roller bearings for extra load capacity.

With the short duty cycles you describe, I suspect a commercial gear reducer will work well. Just take their data sheet and make sure you accurately describe the load case.

David