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MECHANISMS MARIO SIMÓN PUGA 3 D - Coggle Diagram
MECHANISMS MARIO SIMÓN PUGA 3 D
1.MECHANISMS
The most important thing is the driving force that initiates the movement.
The driving force can be a spring, an electric motor or our own muscles.
The motion produced by a motor is transformed and converted by those mechanisms to receiving elements such as wheeks, clock hands, and so n, so that they can do the job for wich they were constructed.
CLASIFICATION OF MECHANISMS.
TRANSMITTING MOTION
rotary
linear
TRANSFORMING MOTION
rotary to linear
rotary to reciprocating
Controlling and regulating motion.
Joining elements
Storing energy
LINEAR MOTION MECHANISM
Mechanisms that transmit motion and force in a straight line from one point to another.
Examples include levers and fixewd, mobile and compound pu7lleys
LEVERS
F is the force or effort applied at one end of the bar.
R is the resistance or load wich acts at the other end of the bar.l
d is the distance from F to the fulcrum
r is the distance from f to the fulcrum
TYPES OF LEVERS
class 1: The fulcrum is between the effort applied and the resistance.
The effect of the effort applied can be multiplied or reduced
Class 2: THe resistance is between the fulcrum and the effort applied.
The effect of the effort applied is always multiplied.
Class 3: The effort applied is between the nfulcrum and the resistance. The effect of the effort applied is always reduced..
Fixed pulley
A fixed pulley is a wheel that has a groove around it into which a rope, chain or belt fits. It rotates around an axle that is fixed to an immobile surface.
A fixed pulley is balanced when the effort F is equal to the resistance of the load, R: F=R
Pulleys are used to raise and lower loads easily because we use our own weight to counteract them.
Moveable pulleys
A moveable pulley is a set of two pulleys- one is fixed while the other can move ina linear direction. A moveable pulley is balanced when it satrisfies this equatin.
The effort required to move a load with amoveable pulley is half the effort needed to move the same load with a fixed pulley.
3Rotary motion mechanisms
These mechanisms transmit motion and effort in a circular way, from the input to the output.
They include friction drivers, pulley systems,gears and worm gears.
3.1 Friction drives
Friction drives made up of two or more wheels that are in contact.
The first wheel is called the primary drive wheel. When i moves, it turns or drives the second or output wheel, causing it to move as well.
The output wheel rotates in the opposite direction of the primary wheel. If we use more than two wheels, each one rotates in the opposite direction to the one next to it.
The ratio between the rotation velocity of the or pulleys depends on the relative siza of the wheels. It is expressed by the following equation:
N1 x D1= N2 x D2= D1/D2=N2/N1
N1 and N2 are the velocities of the primary drive wheel and the output wheel.
These velocities are expressed in revolutions per minute(rpm).
D1 and D2 are the corresponding diameters.
They are expressed in units of leght: usually millimtrea
3.2 Pulleys with belt
They consist in two pulleys or wheels that are a certain distance apart.
3.3 Gear mechanisms and cogwheels
Cogwheels are sets of wheels tat have teth called cogs.
The cogs fit into the spaces between the cogs of another whel, so that one wheel moves the other.
THey transmit a rotary motion between the two connected axles, wich can be parallel, perpendicular or oblique.
Gears can be be cylindrical or conical.
Cylindrical gears
Conical gears
N1 x Z1= N2 X Z2 > z1/Z2 = N2/N1
3.4 WORM GEAR
This is screw that movs a helcal cogwheel that is set perpendicular to the screw .
A worm screwfulfils this equation:
N wheel=N screw x Z grooves/Z wheel
N wheeland N screw are the velocities of the wheel and of the screw.
Z grooveas is the number of grooves of the screw and Z wheel is the number of theeth of the wheel.
Uses: lap counters, gear reduction system,musical tuning keys and windscreen wipers.
3.5 gear mechanisms with a chain
These are two cogwheels with parallel axles that are acertain distance apart, they rotate simultaneously by means of a metal chai or atoothed belt streched over both wheels.
N1 x Z1=N2 x Z2> Z1/Z2 = N2/N1
3.6 Gear train
This is a system ofmore than two gears, connected togheter as show in the diagram.
The rotary motion of the first wheel (1) drives the second wheel (2), and so on.
In the system, the rotary movement of the firat axle in transmitted tothe second by means of wheels 1 and 2.
The gear ratio between the drive wheel(1) and the driven wheel(4) depends on the umber of geared teeth in the system:
N4/N1 = Z! x Z3/Z2 x Z4
3.7 PULLEY TRAINS WITH BELTS
The rotary motion of axle 1 is transmitted to axle 2 by the belt that connects them.
Pulleys 2 and 3 rotate at the same velocity.
The motion of pulley 3 is transmitted to pulley 4 by the belt that connects them.
All the wheels rotate in the same direction·
The gear ratio the drive pulley (1) and the driven pulley (4) depends on the relative size of the pulleys in the system. I'ts expressed as a function of their diameters.
N4/N1 = D1 x D3/D2 x D4