BottleBob wrote in news:ZY2dnTUbrOjiAN7UnZ2dnUVZ snipped-for-privacy@earthlink.com:
I run into this myself from time to time when a competitor claims some high horsepower number more often than not it's at some very short duty cycle. Given that 7-1/2 horsepower is something of a "standard" motor size for a 5 horsepower continuous 7-1/2 30 minute duty rating, I would guess that probably is the motor size. Without any help from gearing or other speed reduction, it would be a fairly weak spindle with only 5 ponies on tap. Then there is the issue of how it's wound and how it's driven. If it's a simple inverter driven four pole motor it would be very weak indeed. A more sophisticated motor/drive can provide a very flat torque curve throughout much of the range.
The spindle bearings still create a drag on power. You can count them up and estimate the loss. Plus like I said a small motor with no reduction to multiply the torque will be weak.
Probably, and probably meant for drilling/tapping in that range rather than say hogging with a face mill.