calculation torque resistant for rotation on support wheels

[iceeyes]

in these days a diatribe between me and my colleague was born regarding the calculation of the resistant torque for the application I describe below a little simplified in a functional way.
a 15000 kg tree is supported on four wheels of which 1 drive and 3 follies.
the need is to rotate the tube up to a speed of 10 rpm. to choose the engine and reducer for this application it is clearly necessary to know the resistant torque, calculation on which the tenzone is born.
Is there someone among you so kind to solve this little problem?
other data that could be useful:
support wheel diameter 250mm
shaft diameter in 240mm support sections
materials: steel.

I hope the description is clear but don't hold back from asking... .

Thank you in advance

 

[Fulvio Romano]

how long does it have to reach 10rpm?
you have to calculate the moment of inertia of the shaft including wheels, from that you can calculate the kinetic energy of the tree to 10rpm. divide for the time you want to reach speed, and get the power that must be absorbed by the tree.
divide for various returns and get the power of the engine.

 

[iceeyes]

and the calculation of the point-resistant couple does not serve anything?

 

[meccanicamg]

first you should post a box because the 4 wheels could be put tangent to the tube in the lower side coupled or all placed on a axis parallel to the tube.

then you have to keep in mind the following things:
- wheel/tube friction
- pipe inertia
- wheel inertia

If the wheel is to be carried away the hose and the 3 crazy wheels you will have depending on the configuration an inertia composed according to the ratio of the diameters of the rollers/shaft, just like it was a gear reducer, then the inertia should be evaluated correctly.

for a study of motor or motorcycle law, I recommend you quaderno tecnico abb n°7.

you can also use the method of the powers of the mtu (see my post about it) and you will calculate depending on the cases (point or at regime or braking) the quantities.

 

[iceeyes]

first you should post a box because the 4 wheels could be put tangent to the tube in the lower side coupled or all placed on a axis parallel to the tube.

then you have to keep in mind the following things:
- wheel/tube friction
- pipe inertia
- wheel inertia

If the wheel is to be carried away the hose and the 3 crazy wheels you will have depending on the configuration an inertia composed according to the ratio of the diameters of the rollers/shaft, just like it was a gear reducer, then the inertia should be evaluated correctly.

for a study of motor or motorcycle law, I recommend you quaderno tecnico abb n°7.

you can also use the method of the powers of the mtu (see my post about it) and you will calculate depending on the cases (point or at regime or braking) the quantities.

You want to apologize for the absence after launching the question, but I've had some things to do these days.

returning to us, in the annex I posted the support scheme of the very simplified tree just to understand what is the moment of reduced inertia.

the moment of inertia, just as explained by mechanicsmg is rather simple to calculate and on that me and my "connect" we agree. the thing on which we have some doubts, as from title, is the strong friction couple.
This was mainly the first point of the matter.
thanks to all for the aid and thanks for the attached technical notebook.

I'll put the ball back to the center.
Good evening.
Thanks again.. .

 

[meccanicamg]

because those wheels transmit movement to others and therefore to the tube it is necessary that the theory of hertz be verified, otherwise nothing is exchanged. at the end are clutch wheels.

 

[iceeyes]

I take up the topic of the discussion, first of all apologising for how I presented the problem, which at a distance of months I do not like at all, what I would like is a help for reasoning.
taking up the suspended project to devote me to more challenging exams, let's see if I can with your help find the right way.
definitions:
p: tree weight (note)
ja: tree inertia moment (note)
jr: wheel inertia moment
ra: shaft radius in the support area (note)
rr: support wheel radius
wa: rotation speed of the wr shaft: rotation speed of the wheel (note)
tau: wa/wr
eta: transmission performance
t: time to go from 0 to wa. (note)
Let's see.
from the balance of the shaft on the supports I find the strength fr that the wheel exercises on the shaft in radial direction and friction force in f*fr crawling condition.
Whereas a safety coefficient of 2 I impose that the driving force on the wheel (transparent force exchanged between the driving wheel and the shaft) is less than 2 times f*fr (adhesion proof).
the moment of inertia of the mad wheel reduced to the axis of the tree is worth:
jr,rid=jr*(wr/wa)^2*(1/age);
the moment of total inertia reported to the motor axis:
_[(Ja+3*Jr,rid)*(wa/wr)^2]*(1/age).
to calculate the power required by the celibate user:
ec,a=0.5*ja_bar*wa^2;
pu=ec,a/t;
but at this point I get the doubt ja_bar=ja or ja_bar=ja+3jr_rid?

 

[meccanicamg]

the motor sees as inertia the following:
1) inertia of the engine itself and its reducer (if present)
2) wheel inertia
3) satellite wheel inertia
4) Main Pipe Inertia
and consequently you need power for each component and each pair of components you will lose power in friction and therefore in heat

 

[iceeyes]

ok, so I can calculate the kinetic energy of rotation of the tree with the moment of inertia equivalent i.e. ja+3jr,rid from which dividing for the time I get the utilitarian power.
for the driving power at that point I divide the pu for the performance of the transmission and the possible reducer.
Right?
obtained the driving power then I can calculate agility moment motor and driving force verifying the condition of grip calculated at the beginning and finally going to choose my motor all by studying the best diameters to give to the wheels and the shaft in the contact zone.

I hope at this point I haven't forgotten anything.