find the driving power?

[Luca93]

Hello. Who could help me with this exercise? Thank you very much.

in a motor enters an unknown power and exits one of 5 kw.
Guided wheel: 800 spins per minute
Wheel diameter led: 0.2 metres
transmission ratio: 1.5.
calculate the diameter of the wheel, the number of turns of the wheel, the torque, the forces that exchange and the driving power.

I calculated the diameter of the wheel by making the ratio between the diameter of the wheel and the transmission ratio.
Later, I calculated the number of wheel turns by making the product between the number of turns of the wheel conducted and the transmission ratio.
Now, how do I find the driving power?

 

[meccanicamg]

Since your exercise does not speak of transmission yields it is assumed that the system is conservative. so the power is never lost and is all transformed.
in reality it is all very different because the transmission will have a yield of 0.9 to go well, so the engine power will be 5/0,9.

attention to the definitions of transmission ratio and reduction ratio.
According to me we are talking from reduction ratio 1.5 so the motor turns to 1200rpm and the wheel diameter will be about 133mm.

but who gave you this exercise has any idea what he was asking you or did you miss a few pieces on the street?
for the forces exchanged are the usual of the gears that we have treated many times and on the site khk gear there are complete pdf with everything.

In the first approximation you can calculate the yield of the gears with the formula of hofer reported in some post, where it says that the yield is worth 1-3,14* friction*(value from 0.5 to 1)*[(1/z1) +/- (1/z2)]

 

[Luca93]

Believe me, the one who gave me the exercise is a professor who when he explains makes understand very little and when he assigns exercises makes understand even less because he gives them without making understand anything, and the text above is identical to that given by him, I have not lost any piece and unfortunately I often ask help here because I am really hard to solve something assigned wrong on a topic that has been explained badly, but fortunately next year I do not have it and I have to resist the last 2 weeks.
Thank you so much for the help, I understand right now! :biggrin:

 

[meccanicamg]

Unfortunately, of teachers of this kind there is full air and then we wonder why the boys do not learn anything... .
However, to specify the transmission ratio discourse, it is defined as z2/z1=d2/d1=n1/n2 and is a greater number of 1 for speed reductions as I said before.
deepen here https://it.m.wikipedia.org/wiki/rapporto_di_trasmissioneIt is already good that does not use the reverse of the transmission ratio that has created so much confusion to too many people.