Gear Calculations using exact length for specific time

[webb415]

I have this conveyor which I am trying to automate i.e. It runs for 5 secs and have a pause of 3 sec, this process is continuous.
I am creating a mechanism where I have a gear of dia 200mm which is fixed (i.e. I can't change its dia) and it is attached to a conveyor.

Now I am introducing a second gear which is variable (i.e. I can change its dia) Now I am thinking that the second gear should have less number of teeths i.e.

"sorry i can't use images yet therefore search in google (half tooth gear)."

because I want a pause of 3 seconds and rotation of 5 seconds in conveyor. I am really confused of how the calculations will be carried out. The rpm of the second gear can also be changed.

I am using 2*pi*r to get the length of the gear circumference however I am not sure what size should be the second gear and at which speed I should rotate to get a 3 sec pause and 5 sec run. I know its complicated but even a little help will be appreciated.

Regards
Webb

 

[Navin A S]

.The calculation for this would be to determine the ratio of the two gears. The gear ratio is determined by dividing the number of teeth on the larger gear by the number of teeth on the smaller gear. For example, if the fixed gear has 100 teeth and the variable gear has 80 teeth, then the gear ratio would be 100/80 = 1.25. This means that for every turn of the fixed gear, the variable gear will turn 1.25 times. To get the desired 3 sec pause and 5 sec run, you can calculate the time it takes for one rotation of the fixed gear by using the circumference formula 2*pi*r, where r is the radius of the gear. Then you can calculate the time for one rotation of the variable gear by multiplying the time for one rotation of the fixed gear by the gear ratio. For example, if the radius of the fixed gear is 100mm, then the time for one rotation of the fixed gear would be 2*pi*100 = 628.3 seconds. If the gear ratio is 1.25, then the time for one rotation of the variable gear would be 628.3 x 1.25 = 785.4 seconds. Then you can adjust the speed of the variable gear so that it completes 785.4 seconds in 8 seconds (3 seconds pause and 5 seconds run). To do this, you can divide 785.4 by 8 and you will get 98.175 rpm as the required speed of the variable gear. I hope this helps.