Rotary. Pulley Systems.

Pulley Systems use a belt to transmit motion and force from the driver shaft to the driven shaft.

Speed changes are made by using different size pulleys on the driver and driven shafts.

Speed changes

By comparing the size of the two pulleys you can calculate the velocity ratio of the system

Calculation

d1 d2

1 2

n1

n2

Pulleys formula:

n1 . d1 = n2 . d2 n1: pulley 1 speed

d1: pulley 1 diameter

n2: pulley 2 speed

d2: pulley 2 diameter

Gears

Gears are toothed wheels, fixed to the driver and driven shafts, which mesh together. The gears have a whole number of teeth.

Gear train

Speed changes are made by using different number of teeth on the driver and driven shafts.

Speed changes

You can calculate the velocity ratio of the system

Calculation

Gears formula:

n1 . Z1 = n2 . Z2

n1: gear 1 speed

Z1: gear 1 teeth

n2: gear 2 speed

Z2: gear 2 teeth

Chain and Sprocket systems

Chain and sprocket systems use a chain to transmit rotary motion from the driver to the driven shaft. Sprocket is the name of the gear when it use a chain.

The mechanism of the bicycle is a typical example

Chain and Sprocket systems

You can use the formula of the gears for this mechanism. It's the same.

n1 . Z1 = n2 . Z2

n1: sprocket 1 speed

Z1: sprocket 1 teeth

n2: sprocket 2 speed

Z2: sprocket 2 teeth

Worm gear

Another way of making large speed reductions is to use a worm gear.You can think of the worm as if it were a gear with 1 tooth.

Worm gear. Watch outWatch out

You can use the formula of the gears for this mechanism. It's the same.

n1 . 1 = n2 . Z2

n1: screw 1 speed

n2: gear 2 speed

Z2: gear 2 teeth

Rack and Pinion Systems.

Rack and pinion systems involve changes between rotary and linear motion.