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MECHANISMS, (.), If wheel 3 makes 1.5 rotations, wheel 4 makes 1.5 x 2 = 3…
MECHANISMS
CHANGES IN SPEED
If we want to increase the speed of a rotary system, we must transmit motion from a larger element to a smaller element
SPEED RATIOS
This happens because the smaller wheel must rotate three times to cover the same linear distance as the big wheel does in only one rotation.
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WORM DRIVE
They interlock with two teeth of a worm gear. The worm gear has got a total of 30 teeth. If the screw makes one rotation, the gear moves forward two teeth.
Transformation of motion
The linear motion can be unidirectional or reciprocating. Reciprocating motions alternate from one side to the other. ROTARY-LINEAR TRANSFORMATION.
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F x d = R x r
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
vIn the picture, you can see the parts of a crank and rod mechanism. Today we find cranks and rods in internal combustion engines, as well as windscreen wiper mechanisms.
Cam mechanisms
In some mechanisms, a spring pushes the follower back to its original position. We can put multiple cams on one shaft, called a camshaft. We can use a camshaft to synchronize the movements of various parts, such as the valves of an internal combustion motor.
Crankshaft mechanism
A crankshaft mechanism can synchronise the movements of various parts, such as the multiple pistons of a car engine.
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If wheel 3 makes 1.5 rotations, wheel 4 makes 1.5 x 2 = 3 rotations.