Side loading of a shaft 1

[rharr]

We have a possible project of converting a machine with a reducer (gear box) being driven directly by a motor through a shaft coupling. The conversion would move the motor off the centerline of the input shaft and add pulleys and belts to reduce the speed of the reducer's input shaft while keeping the motor speed up.

My question concerns the side loading of the shafts that didn't previously experience this. Are reducers and motors built with the assumption they could be used with belts and the bearings are selected accordingly? Or could it be that the bearings were selected per the application and now we won't be able to offset the motor?

I don't have the nameplate information at this time to contact the manufacturers, I just thought I'd ask before we went too far down this path.

FYI: we're talking about 300 to 500 Hp motors.

 

[dvd]

If you look in the manufacturer's literature for the "overhung load" rating you should be able to determine the point of application and magnitude of allowable side loading. Most manufacturers explain this pretty well in their application literature.

 

[JJPellin]

The design literature for a cog belt drive includes a table showing minimum sprocket size based on horsepower and speed. The basis of this table is the maximum allowable side load for a standard NEMA frame motor of that power rating. The smaller the sprockets, the larger the side load. For the driven machine, you will need more information to determine if the input shaft bearing can take the load.

Johnny Pellin

 

[MoMiner]

I need help locating a wire rope/pulley design or recommendations book or site. I am reviewing an application using 3/8"- 7x19 cable being pulled around 2 - 4" pulleys (180 degree wraps - 2 to 1 pull ratio) lifting 2500 lbs.

 

[rharr]

Hello MoMiner,

I'll start by sending you to the same place I was sent with my question - the manufacturer.

The manufacturer of your cable may have some recommendations. My first thought is the 4" pulley seems small for a 3/8" cable if it will be used frequently. Cable hoists use much larger pulleys and the load per length of cable isn't as high.

Isn't this a simple block and tackle? Try looking that up.