calcualting electric motor size/torque required?

how would i work out what torque is required to move.

a 250kg weight object on rails/wheels. pulled by an electric motor turning a 50mm cog on chain. max speed would be 120m/min so cog needs to turn at 2400rpm.

250kg weight on level ground.

250kg weight up a 1/12 gradient.

a 250kg weight on rails wheels pulled by an electric motor turning a 50mm cog on chain. max speed would be 60m/min so cog needs to turn at 1200rpm.

250kg weight on level ground.

250kg weight up a 1/5 gradient.

im clueless here.

what is the diameter of the wheels.

50mm but they are not doing any driving. just rolling

Hi weisyboy,
You would probably need a motor/gearbox arrangement and as such you could talk to company like SEW who would be able to give you the answers as they can calculate the size gearbox and motor to suite the gearbox.

Regards,
Keith.