What is this ODTF motor type?

I have this motor on my compressor. It says ODTF. I understand it is an open frame, drip proof, but what is the Tandem Fan thing all about? Can anyone find an online reference picture of what mechanically is going on inside this motor? Thanks...

Jim, mine has same motor - AFAIK, only diff is terminology - same fan on end of motor shaft as TEFC, not sure if there's any reason it isn't called "ODFC". Baldor's site isn't much help either... Steve

Main thing on Open Dripproof is environment - TEFC is good for dirty environment, Open Dripproof needs to be inside away from sources of grinding, corrosive gases, etc - so where yours is going, it should be no problem.

nice answer bukit

-diskfaktory

I emailed a Baldor guy and got this...
"Open Drip Proof, tandem fan is a special open motor with an external fan to assist in cooling this open motor. Not very common."
So there ya have it. It has an external fan, like a TEFC, and it has that same fan cover like the TEFC too. But I assume the fan blows air into or out of the open frame motor, instead of over the outside of, like a TEFC does it. I guess this should make it cool much better than a simple open motor.