### Author Topic: calculations and fundamentals once again  (Read 1775 times)

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#### cervantes

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##### calculations and fundamentals once again
« on: May 26, 2016, 02:51:07 PM »
Hi all,

that's me again with my thoughts and doubts.

First of all – I do not want to ask someone to calculate something for me.
I did my best (I hope correctly, based on your tutorials) – can anyone check it and answer my additional questions? I am especially interested in these questions – I always have some doubts during calculations.

Ok, so I need to roughly calculate carousel storage motor parameters. This is not a robot but I found your tutorials applicable for this.

I am assuming that only 5 of boxes on one side will be loaded with 200 kg. This is the worst case.
Imagine I want to lift the lowest one up to 6 meters in let’s say 30 seconds.
W= mgh= (5*200 kg) * 10 m/s^2 * 6 m = 60000J = 60 kJ
P= W/t = 60000 J/30 s = 2000 W = 2 kW <- required motor power

1) There is a gear in my sketch – does this gear has any influence to formulas for power used above?

2) By the way – if all boxes will be loaded to max can it be calculated like a lift with counterweight?
Can anyone provide more information about “counterweight effect” which “helps” motor?

Now let’s calculate a torque_motor and speed – it seems that tutorial example is the same:
torque_motor / radius_1 = torque_2 / radius_2
torque_2 / radius_2 = weight -> torque_2 = weight * radius_2
so:
torque_motor / radius_1 = (weight * radius_2) / radius_2 -> torque_motor = weight * radius_1
so torque_motor = 10000N * 0,5m (more or less) = 5000 Nm

3) This is a minimum of course – how much additional percentage do you suggest to add considering belt efficiency etc.?

speed (0,2m/sec)
rps_motor * radius_1 = rps_gear_2 * radius_2
rps_gear2 * 2 * pi * radius_2 = velocity_weight -> rps_gear2 = velocity_weight / (2 * pi * radius_2)
so
rps_motor = ((velocity_weight / (2 * pi * radius_2)) * radius_2) / radius_1
rps_motor = velocity_weight / (2 * pi * radius_1)

4) BUT NOW  PLEASE NOTICE that there is no radius_2 in both of these equations (torque and speed)! So what’s the reason of this gear (bigger pulley)?... maybe equations are in the fact are not ok? so - looks like the weight can be attached directly to motor pulley?....

5) By the way – if torque and speed are given now, isn’t it natural that there must be a motor power which is combined with this parameters – on the other hand – was it required to determine power at the beginning of this post?

6) Any other tips for this application?

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