Calculate Horsepower to rotate an object resting on a thruust bearing
Calculate Horsepower to rotate an object resting on a thruust bearing
(OP)
Hi...trying to determine if i need to consider both efficiency and c.o.f. of the thrustv bearing when determining required torque in order to obtain hp.
any insight appereciated.
any insight appereciated.





RE: Calculate Horsepower to rotate an object resting on a thruust bearing
Post up some numbers
RE: Calculate Horsepower to rotate an object resting on a thruust bearing
RE: Calculate Horsepower to rotate an object resting on a thruust bearing
RE: Calculate Horsepower to rotate an object resting on a thruust bearing
Patricia Lougheed
******
Please see FAQ731-376: Eng-Tips.com Forum Policies: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.
RE: Calculate Horsepower to rotate an object resting on a thruust bearing
Customer comment was concerning the 0.95 value for efficiency, wanted to know why that value is assumed conservative.
The only empirical value i got from the vendor was the c.o.f. - i am debating either removing the assumed efficiency completely or somehow converting the c.o.f. into an efficiency value to calculate accelerating torque.
Any ideas on how to transform a cof to an efficiency????????!!!!!
Thanks!
RE: Calculate Horsepower to rotate an object resting on a thruust bearing
It gets messy after that.
RE: Calculate Horsepower to rotate an object resting on a thruust bearing
RE: Calculate Horsepower to rotate an object resting on a thruust bearing
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Calculate Horsepower to rotate an object resting on a thruust bearing
Efficiency is output/input.
What is the "output" of a thrust bearing?
If you have cof, thrust and effective radius then you can convert that to torque that goes away and does nothing useful for your system.
RE: Calculate Horsepower to rotate an object resting on a thruust bearing
eff = 1-c.o.f.
thoughts?
RE: Calculate Horsepower to rotate an object resting on a thruust bearing
You input thrust in lbs, your output is loss due to friction in ft-lbs based on the thrust, thrust bearing efficiency, and RPM.
To translate that to overall efficiency of your machine is an entirely different matter. A 95% efficient thrust bearing could cause:
1% loss in overall efficiency of a 200hp machine
2% loss in overall efficiency of a 100hp machine.
That was the missing link in my head at least. Learn something every day.
RE: Calculate Horsepower to rotate an object resting on a thruust bearing
RE: Calculate Horsepower to rotate an object resting on a thruust bearing
Wrong.
RE: Calculate Horsepower to rotate an object resting on a thruust bearing
It's that simple.
RE: Calculate Horsepower to rotate an object resting on a thruust bearing
thanks.
RE: Calculate Horsepower to rotate an object resting on a thruust bearing
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Calculate Horsepower to rotate an object resting on a thruust bearing
RE: Calculate Horsepower to rotate an object resting on a thruust bearing
A "thrust bearing" has no "rolling resistance" per se, because it is unloaded (zero force) UNLESS it is resisting a linear force up or down the shaft. Then, the instantaneous thrust bearing resistance is going to depend on the instantaneous load axially in the shaft at that particular moment in time - NOT the weight of the shaft and rotating equipment that are being held in place by the roller bearings. As the turbine or pump comes up to speed, or as load changes on the pump, thrust bearing resistance changes.
RE: Calculate Horsepower to rotate an object resting on a thruust bearing
(I was playing around with TeXmacs)