pulley

[mars]

hi im a total newbie can anone tell me if i need to put a smaller or larger pulley on this motor to slow down the two top pulleys and shafts .. plz thx

[Geof]

Smaller.

With pulleys, and gears, the larger one rotates slower than the smaller one.

The difference in the speeds depends on the difference in size; if the larger pulley is twice the size of the smaller it will run at half the rpm of the smaller one.

The calculation is diameter of small divided by diameter of large; a 4" pulley drives an 8" pulley at 4/8 = 1/2 the speed of the 4" pulley.

Very often the difference in speed is expressed as a ratio. In the 4" driving 8" example the reduction in speed is described as two to one; written as 2 : 1 because the driver pulley the 4" rotates twice as fast as the driven pulley the 8" one.

[LeeWay]

Smaller. It all depends where the pulley is located. A smaller pulley on the motor side will turn those two upper pulleys slower. Larger pulleys above would do the same thing.

[mars]

Originally Posted by Geof Smaller. With pulleys, and gears, the larger one rotates slower than the smaller one. The difference in the speeds depends on the difference in size; if the larger pulley is twice the size of the smaller it will run at half the rpm of the smaller one. The calculation is diameter of small divided by diameter of large; a 4" pulley drives an 8" pulley at 4/8 = 1/2 the speed of the 4" pulley. Very often the difference in speed is expressed as a ratio. In the 4" driving 8" example the reduction in speed is described as two to one; written as 2 : 1 because the driver pulley the 4" rotates twice as fast as the driven pulley the 8" one.

/////////// thanks very much all clear now

[mars]

Originally Posted by LeeWay Smaller. It all depends where the pulley is located. A smaller pulley on the motor side will turn those two upper pulleys slower. Larger pulleys above would do the same thing.

thanks man