huytien1042 Posts: 3, Reputation: 1 New Member #1 Oct 19, 2010, 08:01 AM
Need help for torque calculations
I have buildup the wheel that weight about 200Kg and hookup to the motor in vertical direction. It is operated at variation speeds ranges 500-1000 rpm. Now I am looking for brake just in case of emergency stop so I would like to know how many torque force (N-m or Ft-lbs) to buy the right kind of brake. Your helps on this matter are very-very appreciated.
HN
 ebaines Posts: 12,132, Reputation: 1307 Expert #2 Nov 1, 2010, 11:40 AM

How quickly do you want this brake to be able to stop the wheel?
 huytien1042 Posts: 3, Reputation: 1 New Member #3 Nov 9, 2010, 08:49 AM
Originally Posted by ebaines
How quickly do you want this brake to be able to stop the wheel?
It doesn't need to be stopped instantly but slowly in about 1min max.
I use this for VAWT. This emergency stop is just for repair only.
Thanks for helps.
HN
 ebaines Posts: 12,132, Reputation: 1307 Expert #4 Nov 9, 2010, 09:04 AM

What's the diameter of the wheel in meters?

The torque that you will need to slow the wheel is:

$
T = I \alpha
$

where I = moment of intertia, which for a wheel of uniform cross-section, radius R, and mass m is:

$
I = \frac 1 2 mR^2\ = \ \frac 1 2 (200Kg) R^2
$

and the acceleration of the wheel in radians per second squared is:

$
\alpha = \frac {\Delta \omega} {\Delta t}
$

You're starting with

$
\omega = 1000 \frac {Rev} {Min} \times 2 \pi \frac {rad} {Rev} \times \frac {1 min} {60 sec} = 105 \frac {rad} {s}.
$

To slow this over a period of 60 seconds requiresa deceleration of :

$
\alpha = \frac {\Delta \omega} {\Delta t} \ = \ \frac {105 Rad/s} {60 sec}\ =\ 1.75 \frac {Rad} {s^2}
$

So the total torque needed is:

$
T = I \alpha = \frac 1 2 (200Kg) R^2 \ \times \ 1.75 \frac 1 {s^2}
$

This result is in N-m. Be sure to specify R in terms of meters. And please verify that the wheel has uniform cross-section.
 huytien1042 Posts: 3, Reputation: 1 New Member #5 Nov 10, 2010, 02:17 PM

Dear Ebaines,
Thanks a lot for your helps . Now I can figure out how many torques that applied for the Electromagnetic Brake that I am looking for.
Best regards.
Huy Nguyễn

 Question Tools Search this Question Search this Question: Advanced Search

## Check out some similar questions!

Torque spec [ 2 Answers ]

What is the torque setting for the serpentine belt tensioner on a 1997 Lumina with the 3.1 V6?

Torque calculations [ 1 Answers ]

I would like to know how to calculate torque required to turn an plastic extruder screw 120mm in dia and 3.6mt in length at 70 rpm. Material conveyed by screw (which is inside a barrel) is high density polyethylene of MFI 0.1.

25cm3 of a commercial bleach NAOCl is diluted to 250 cm3 . A 25 cm3 of the diluted solution is added to an excess of potassium iodide solution and titrated against 0.200 M sodium thiosulphate solution. The volume used was 18.5 cm3. What I s the concentration of sodium chlorate in the bleach in mol...

What is the maximum torque exerted by a 60 kg perspn riding a bicycle if the person puts all her weight on each pedal when climbing a hill? The pedals rotate in a circle of 18.0 cm?:confused: :confused: :confused: :confused:

Torque and light [ 1 Answers ]

How is light used in television? Like how do we see it? And what is torque?