Fisher Price Gear Box Problem

[kevinbrice]

Hi. We constructed a gear box for our fisher price motor to spin a set of rollers out of plastic (delrin) pulleys and rubber cords. This technique worked well for us last year, but we desired a lower spin speed then. Right now the gearbox is set at a 9:1 reduction which is the desired speed of our rollers. However, whenever the system interacts with a ball, it is moving at such I high speed the frictional torque is easily overcome in the outer pulleys of the system. We have debated migrating the drive to timing belts or chain... Also, what is the minimum reduction we could use with the fisher price to still keep some (a good level) of torque? Any ideas or different roller powering options would be much appreciated.