# Torque and power.

hi,
i am doing a project on frame tilting arrangement where the sheet metal stacks mounted on a shaft have to be rotated by 180 degrees. the mass of the shaft is 15 tonnes. to calculate the torque required i found the mass moment of inertia and multiplied it by angular acceleration. the total time taken to rotate the stacks is 25 minutes.so the speed is extremely slow. since the setup reaches the speed instantaneously, for calculating angular acceleration i took time as 0.1 sec(i don know whether this is right). i got very low torque value and also low power.(it came in watts!). i donot know the mistake . please help asap.

russ_watters
Mentor
Is the shaft really perfectly balanced if there are frames mounted on it? Perhaps you could clarify/draw a diagram of the situation...

If, indeed, the shaft is perfectly balanced, then friction forces are the largest factor in figuring out how fast you can rotate it.

But I would certainly think that a couple hundred watt motor could provide enough torque to turn it if you are looking to rotate it over a period of many minutes. When you gear down the motor that far, the torque can be enormous.

hi,
the shafts are perfectly balanced. they have a pair of c-brackets. i have attached a schematic drawing. the torque is very high. and the speed of 0.02 rpm is reached instantaneously .
so to find the angular accln, what is the time to be taken for calculation purpose. please guide me.

this is the pdf format of my drawing.

#### Attachments

• FRAME LIFTING ARRANGEMENT.pdf
31.3 KB · Views: 145
one more question.....
can we add up the mass moment of inertia's of different bodies rotating about the same axis to get the total mass moment of inertia of the entire system....?