Picking Out Roller Chain

[Andy Brockway]

Adam,

In its simplest form you need to calculate the torque at each sprocket and the find the resultant force on the chain. For example if you have a torque at the sprocket of 2000 inch-lbs and have a 4 inch pitch diameter sprocket, the force at the pitch line on the chain is 2000/2 = 1000 lbs. Since we like to have a safety factor of 2-3 than you would select a chain size with a breaking load in the 2000-3000 range minimum. #35 falls into this range. The load needs to be calculated from the direction that is applying the greatest force. For the drive, the wheels generally slip before the maximum torque of the motors is achieved. A lift mechanism may get jammed or try to lift an immovable object, the torque in this case is from the motor side.

Word of caution, sprocket teeth can also break. Try to use a sprocket with as many teeth as possible, the load is shared by each tooth so the more the merrier.