flour mill belt drive

Can you rephrase the question as it doesn't make sense. I'm not taking the piss cos English is obviously not your first language but you wont get any response to that question unless you it makes sense.

why flour mill is kept with too large centre distance

between motor pulley and flour mill pulley

Is it an electric motor. If so I would make the assumption that you don't want flour covering your motor. I have no idea what motor it is or what size the motor and pulleys are. Does the motor need ventilation to keep it cool and therefor has to be housed away from the mill. Maybe the mill is a clean area and the driving motor is a diesel engine. The two don't go hand in hand so you may need to keep the drive motor away from the mill. Does the mill create alot of dust which may be explosive?

Just don't know unless you describe what is actually there.

Agreed - reminds me of the question Why does the giraffe have such a long neck? Answer - because its head is so far from its body.

Codey

We need a better understanding of the problem.