#### d1eng

##### Mechanical

- Mar 5, 2003

- 8

I have 4 vertical power screws which are all linked together by a horizontal chain and sprocket drive. So i have 4 sprockets of the same pitch diameter (one on each screw) and 1 chain (running on the periphery of all the the sprockets). There is a handwheel ontop one of the power screws, therefore turning the handwheel turns all the screws at the same time.

I am building a lifting device that uses these 4 power screws. I already calculated the torque required to lift the load to be 15 Nm. But my question is, how do i determine the maximum torque required to initiate the chain drive? Im sure the answer is really simple but i just dont see it.

There is no slack side on the chain, so my 1st instinct would be to take the intial tension on the chain and multiply it by the pitch diameter. then multiply this value by 4 to obtain my final value. is this correct? Or should i consider the final speed of the chain drive and the friction.

I would appreciate any suggestions