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MECHANISMS - Coggle Diagram
MECHANISMS
1. MECHANISMS
Aeround us we can see many moving objects and mechamisms that produce movement that we can aslo call
motion
How do these objects move?
The chain gear of a bicycle or the gears of a clock are some of the simpler mechanisms that can be found in many objects.
They have diverse uses
Telling the time
entretening childrens in the park
Trasporting people from A to B
The most important element in all of them is teh
driving force
.
CAN BE
electric motor
muscles
sparing
Mechanisms are devices that transmit and convert forces and motion from a diving force or
input element
to an
output element
DIVING FORCE
MECANISM
OUTPUT ELEMENT
2.LINEAR MOTION MECHANISMS
Mechanisms that transmit motion and force in a straight line frome one point to onother.
Exemples incluide
levers
and
fixed
,
mobile
compund pulleys
.
2.1. LEVERS
A lever is a
rigid bar
that is suported by a fulcrum.
:check:
R
is the resistence or
load
wich acts at the otherend of the bar
:check:
d
is the distance from
F
to the fulcrum
:check:
r
is the distance from
R
to the fulcrum.
:check:
F
is the force or
effort
applied at on end of the bar
The following equation indicates a balanced lever:
F x d= R x r
TYPES OF LEVERS
CLASS 1
the fulcrum is in the middle of the effort and the load.
1 more item...
CLASS 2
the load is in the middle between the fulcrum and the effort.
1 more item...
CLASS 3
the effort is in the middle between the fulcrum and the load.
1 more item...
2.2 FIXED PULLEY
A fixed pully is a wheel that has a
grove
around it into which a rope chain or belt fits
A foxed pulley
is balanced when the effort F is equal to the resistemce of the load, R:
F=R
USES
: wells and gym equipamnet
2.3. MOVABLE PULLEY
A
movable pulley
is a set of two pulleys
A movable pulley is balanced when is satisfies this equation:
F=R/2
2.4.COMPOUND PULLEY
This is a system of fixed and movable pulley, often called
block and tackle.
USES
: Lifts, goods lifts and cranes
3. ROTARY MOTION MECHANISMS
These mechanisms transmit motion and effort in a circular way, frome the input to the output.
3.1.FRICTION DRIVES
Friction drives are made up of two or more wheels that are in contact. The frist wheel is called the
primary drive wheel
. when it moves, it turns or
drive
the seconde or
output wheel
, causing to move as well.
The radio between the rotation velocityof the weels or pulleys depends on the relative size of the wheels. It is expressed by following eqation:
N1·D1=N2·D2 :arrow_right: D1/D2=N2/N1
:eight_pointed_black_star: N1 and N2 are the
velocites
of the
primary drive wheel
and the **output wheel.
USES
: often in industry to make metal sheets...
:eight_pointed_black_star:D! and D2 are the coresponding diameters
3.2.PULLEYS WITH BELT
They consist of two pulleys or wheels that are a ceratindistance aparat.
USES
: INDUSTRIAL MACHEINES...
3.5. GEAR MECHANISMS WITH A CHAIN
These are two cogwheeles with parallel axles that are a ceratin distance apart, they route simultaneously by means of a
metal chain
or a
toothed belt
sterched over both wheels.
The relation between the rotation velocities of the wheels depends on the number of teeth on each gear.
N1·Z1=N2·Z1 :arrow_right:Z1/Z2=N2/N1
USES
: Industrial machinery, engines and motors
3.6. GEAR TRAIN
This are a system of more than two gears, connected together as shoun in the diagram
The gear ratio between the drive wheel (1) and the driven wheel (4) depends on the number of gered teeth in the system:
N4/N1=Z1·Z3/Z2·Z4
USES
: Machine tools, robotics...
3.7. PULLEY TRAINS WITH BELTS
This are a system of pulley or wheels, with a belt formed by mopre than two wheels.
The gear ratio between the drive pulley (1) and the pulley (4) depends on the relative size of the pulleys in the system. It´s exprressed as a function of thier diameters.
N4/N1=D1·D3/D2·D4
USES:
machine tools and drills
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VARIATION IN VELOCITY
Apart from transmitting force and motion, rotary transmission mechanisms allow velocity to vary.
CONSTANR SYSTEM
REDUCING SYSTEM
MULTIPLYING SYSTEM
5. OTHER MECHANISMS
5.1. MECHANISMS FOR CONTROLLING AND DIRECTING MOTION
The most typicalmechansm of this type is the
ratchet
USES
: watch-making, securitycables and brakes
there are many types of brakes
DISC BRAKES
BAND BRAKES
DRUM BRAKES
5.2. MECHANISMS THAT STORE ENERGY
Springs
are devices that absorb energy. this energy can be released later.
litle by litele
or
all at once
Springs work in different ways:
BY TRACTION
BY TORSION
BY COMPRESSION
5.3.CONNECTING MECHANISMS
Movable connections
are used to connect shafts that can move along the axle or at an angle to each other.
5.4. Supports: bushings and bearings
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Clutches
are mechanisms tahat allow axles or shafts to be connected or separeted.
Fixed connections
are used to makeperment connections between axle and shafts
4. MECHANISMS THAT TRANSFORM MOTION
There are two ways in which can be transformed:
:arrow_forward:From rotary into linear
4.1. FORM ROTARY INTO LINEAR
RACK AND PINION SYSTEM
This uses a
pinion
that is a small cogwheel, mounted on a
rack
that is a toothed belt or bar.
The ratio between the number of rotations of the pinion and the velocity of the movement of the rack is expressed by this eqation:
L=P·Z·N
USES
:bench drills, corkscrews
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NUT AND BOLT SYSTEM
This consist of a
bolt
or
threadedbar
and a
nut
that has the same interior diameter as the diameter of the bolt
USES
: presses, taps...
WINCH AND CRANK HANDLE
A
crank
is a bar attached toan axle that is used to turn it. A
winch and crank handle
system consist of a drum rhat rotates and a crank handle that allows to pull oe lift objects.
USES
: roller blinds, coffe grinders...
:arrow_forward:From rotary into reciprocating
4.2. FROM ROTARY INTO RECIPROCATING MOTION
CRANK-LINK-SLIDER
this is composed of a
crank
and a rod called
conneting rod
or
link
This device was very important in the development of
steam engines
USES
: internal combustion engines, machine tools...
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CRANKSHAFT
This is a set of conneting rods attached to a
jointed axle
USES
: combustion engines and sewing machimes
CAM
This is basically a rotating objetc that pushes a
follower
as it moves.
USES
: combustion engines , automatic system...
A set of cams fixed om the same axle is called
camshaft
ECCENTRIC CAM
This consist of a wheel with an
offcentre rotation axle
that dose not coincide with the centre of its circumference,
USES
: sewing machines, windscreen wipers
