# Mechanisms II.

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Mechanisms II

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

Speed changes Speed changes are made by using different size pulleys on the driver and driven shafts. By comparing the size of the two pulleys you can calculate the velocity ratio of the system

Calculation Pulleys formula: n1 . d1 = n2 . d2 1 2 n1: pulley 1 speed
d1: pulley 1 diameter n2: pulley 2 speed d2: pulley 2 diameter d1 d2 1 2 n1 n2

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 Speed changes are made by using different number of teeth on the driver and driven shafts. 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 out n1 . 1 = n2 . Z2
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.

The End