4.2. RECIPROCATING ROTARY - LINEAR TRANSFORMATION

The pedal mechanism of a bicycle transforms the reciprocating movements of our legs into continuous rotary motion. In a similar way, the pistons of a car engine produce a reciprocating linear motion that turns the wheels.

Crank and rod mechanism

The piston moves a rod forward and backward. This rod turns the first wheel. The second wheel turns because it's connected to the first wheel by another rod.

USES: This mechanism was important for the fist steam engines.

Crankshaft mechanism

We can connect multiply rods to one shaft. The rods are connected to cranks, and the cranks are connected to the crankshaft.

USES: We can use crankshaft for combustion motors that use pistons.

Cam mechanisms

A cam is an irregulary shaped device that rotates on a shaft. When the cam rotates, it pushes a special bar called a follower. The follower can move other parts or it can turn a switch on and off.

We can put multiple cams on one shaft, called a camshaft. We can use it to synchronize the movements of various parts, such as the valves of an internal combustion motor.

USES: We can find camshafts in toys, automatic tools and combustion motors.

USES: There are often eccentric cams in sewing machines and other devices that transform rotary to linear motion.