“MECHANISMS” - educastur.princast

UNIDAD DIDÁCTICA 

“MECHANISMS”

ÍNDICE 

1. INTRODUCCIÓN -------------------------------------------------------------------------------------------- 3 

2. CONTENIDOS ----------------------------------------------------------------------------------------------- 5 

3. OBJETIVOS --------------------------------------------------------------------------------------------------- 5 

4. METODOLOGÍA--------------------------------------------------------------------------------------------- 5 

5. SECUENCIACIÓN ------------------------------------------------------------------------------------------- 5 

6. COMPETENCIAS BÁSICAS ------------------------------------------------------------------------------ 7 

7. MATERIALES Y ESPACIOS ------------------------------------------------------------------------------ 8 

8. EVALUACIÓN ----------------------------------------------------------------------------------------------- 8 

9. ANEXO: FICHAS -------------------------------------------------------------------------------------------- 8 

a) GLOSARIO DE TÉRMINOS -------------------------------------------------------------------------------- 9 

b) FICHAS DE TEORÍA -------------------------------------------------------------------------------------- 13 

SIMPLE MACHINES ------------------------------------------------------------------------ 14 

ROTARY SYSTEMS ------------------------------------------------------------------------ 19 

OTHER MECANISMS ---------------------------------------------------------------------- 22 

TRAINS OF MECANISMS ----------------------------------------------------------------- 23 

c) FICHAS DE PROBLEMAS -------------------------------------------------------------------------------- 26 

d) FICHAS DE ACTIVIDADES PARA EL AULA DE INFORMÁTICA --------------------------------- 32 

e) FICHAS SOBRE EL PROYECTO DE TALLER -------------------------------------------------------- 64 

f) FOTOCOPIA DE EXAMEN ------------------------------------------------------------------------------- 65 

- Versión en inglés: ------------------------------------------------------------------------------------ 65 

- Versión en español ---------------------------------------------------------------------------------- 67 

g) IN THE ENGLISH LESSON ------------------------------------------------------------------------------- 70 

Mechanisms Unidad didáctica 

Technologies - IES Sánchez Lastra (Mieres) 

2

1. INTRODUCCIÓN 

Unidad didáctica: 

MECHANISMS 

Materia: 

TECNOLOGÍAS 

Curso: 

2º de ESO 

Bloque de contenidos: 

BLOQUE 7 

“Mecanismos” 

Por ser el primer curso en el que se imparte “Tecnologías”, no se espera 

que el alumnado posea conocimientos previos precisos relativos a operadores 

mecánicos; si acaso, aquello que hayan podido estudiar en “Conocimiento del 

medio”. 

A pesar de ello, no les son desconocidos ninguno de los mecanismos 

que se les irán presentando, pues aparecen en su entorno cotidiano (desde 

unas simples tijeras hasta cualquier máquina compleja) e incluso su propio 

cuerpo puede ser analizado como un conjunto de mecanismos actuando 

conjuntamente. 

Para el desarrollo de la unidad se plantean 12 sesiones, tal como se 

muestran en la tabla siguiente. 



3

Sesión Aula Planteamiento 

1 Teoría 

2 Teoría 

3 Taller 

4 Teoría 

5 Informática 

Explicación del contenido teórico. 

Resolución de problemas. 

Corrección de problemas. 



Planteamiento de un proyecto técnico. 

Inicio del proyecto. 

Corrección de problemas. 



Consulta de información en Internet. 

Actividades relativas a la información en Internet. 

6 Taller Continuación del proyecto. 

7 Teoría 

Corrección y resolución de problemas. 

Planteamiento de un trabajo de investigación. 

8 Informática Actividades relativas a información en Internet 

9 Taller Continuación del proyecto. 

10 Teoría Evaluación de los contenidos teóricos adquiridos. 

11 Informática 

12 Taller 

Actividades relativas a información localizada en 

Internet 

Finalización del proyecto. 

Evaluación del proyecto. 



4

2. CONTENIDOS 

No lingüísticos: 

(a) Concepto de máquina y mecanismo. Conocimiento de las máquinas 

simples (palanca, polea, rueda, plano inclinado y cuña). 

(b) Palancas y poleas. 

(c) Mecanismos de transmisión y transformación de movimiento. 

Ecuaciones fundamentales (ecuación de transmisión y relación de 

transmisión). 

(d) Simulaciones informáticas de los mecanismos mencionados. 

(e) Diseño y construcción de una maqueta que incluya algún mecanismo 

de transmisión y transformación del movimiento. 

Lingüísticos: 

(a) Conocimiento de los nombres de los principales mecanismos, a partir 

del glosario de términos que se facilita (Anexo fichas: (a) Glosario de términos). 

(b) Realización de descripciones orales y escritas complejas mediante el 

uso de los relativos. 

(c) Comprensión de textos orales y escritos especializados en los que se 

explica el funcionamiento de los mecanismos más comunes. 

3. OBJETIVOS 

1. Analizar sistemas técnicos para comprender su funcionamiento, 

conocer sus elementos y las funciones que realizan. 

2. Abordar con autonomía y creatividad, individualmente y en grupo, 

problemas tecnológicos, tanto teóricos y como prácticos. 

3. Utilizar la lengua extranjera como instrumento de comunicación en 

el aula y de investigación. 

4. METODOLOGÍA 

Se desarrolla la unidad siguiendo cuatro estrategias metodológicas: 

1. Clase magistral: exposición teórica. 

2. Método de resolución de problemas: resolución de problemas 

teóricos mediante la aplicación de ecuaciones. 

3. Método de proyectos (método para la resolución de problemas 

prácticos): diseño y construcción de una maqueta. 

4. Nuevas tecnologías: simulaciones informáticas. 

5. SECUENCIACIÓN 

La siguiente tabla muestra la temporalización, secuenciación y los 

materiales necesarios para llevar a cabo la unidad didáctica planteada: 



5

Nº Secuenciación y temporalización Materiales 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

Explicación teórica: introducción y 

palancas (20’). 

Resolución de problemas de palancas 

(35’). 

Corrección de problemas de palancas 

(15’). 

Explicación teórica: poleas (20’). 

Resolución de problemas de poleas 

(20’). 

Planteamiento del proyecto: martillo 

hidráulico (10’). 

Inicio del proyecto (40’). 

Ordenar el taller (5’). 

Corrección de problemas (15’). 

Explicación teórica: mecanismos de 

transmisión circular (25’). 

Resolución de problemas de 

mecanismos de transmisión circular 

(15’). 

Dar a conocer las páginas que se van 

a visitar y el modo de trabajar con 

ellas (10’). 

Resolución de actividades relativas a 

las páginas a visitar (45’). 

Continuación del proyecto (50’). 


Resolución de problemas (50’). 

Investigar sobre el resto de 

mecanismos que aparecen en las 

hojas y libro de teoría (5’). 


las páginas a visitar (55’). 

Continuación del proyecto (50’) 


Prueba escrita (55’).sobre: 

- contenidos teóricos, 

- resolución de problemas. 


las páginas a visitar (55’) 

Continuación del proyecto (30’). 

Evaluación del proyecto y resolución 

de los posibles problemas (20’). 




Libro de texto. 

Fichas de teoría (Anexo fichas: (b) 

Fichas de teoría). 

Fichas de problemas (Anexo 

fichas: (c) Fichas de problemas). 






Ficha explicativa (Anexo fichas: (e) 

Fichas sobre el proyecto de taller). 

Madera. 


Fichas de de teoría (Anexo fichas: 

(b) Fichas de teoría). 

Fichas de de problemas (Anexo 


Dirección de dos páginas Web 

de interés. 

Fichas con las actividades a 

realizar (Anexo fichas: (d) Fichas de 

actividades para el aula de informática). 

Materiales fungibles que se 

vayan necesitando. 






Fichas con las actividades a 





Fotocopia de la prueba a realizar 

(Anexo fichas: (f) Fotocopia de 

examen). 

Fichas de las actividades a 





6

6. COMPETENCIAS BÁSICAS 

Competencia en comunicación lingüística: 

- Utilización de la lengua extranjera como vehículo de comunicación en el 

aula. 

- Lectura e interpretación de textos técnicos. 

- Adquisición de vocabulario específico 

- Descripción de diversos tipos de mecanismos simples y complejos. 

Competencia matemática: 

- Uso instrumental de herramientas matemáticas. 

- Resolución de problemas basados en la aplicación de expresiones 

matemáticas, referidas a principios físicos, que resuelven problemas 

prácticos. 

Competencia en el conocimiento y la interacción con el mundo físico: 

- Desarrollo de destrezas técnicas para manipular objetos con precisión y 

seguridad. 

- Acceso y utilización de información obtenida de Internet, de modo que 

puedan aplicarla al proceso de resolución de problemas. 

- Uso de las tecnologías de la información y la comunicación como 

herramienta de simulación de procesos tecnológicos. 

Competencia social y ciudadana: 

- A la hora de abordar proyectos de taller en grupo, expresar y discutir 

adecuadamente ideas y razonamientos, escuchar a los demás, gestionar 

conflictos y tomar decisiones, adoptando actitudes de respeto y tolerancia 

hacia los demás. 

Competencia cultural y artística: 

- Hacer notar que el diseño de los objetos tecnológicos a lo largo de la 

historia está influenciado por la cultura de la sociedad de pertenencia. 

Competencia para aprender a aprender: 

- El método de resolución de problemas proporciona un medio para darnos 

cuenta de lo que sabemos y de nuestras carencias, permitiéndonos 

progresar en las posibles soluciones. 

Autonomía e iniciativa personal: 

- Planteamiento adecuado de los problemas, que siendo analizados desde 

distintos puntos de vista, lleven a elegir la solución más adecuada. 

- Planificación, ejecución y evaluación del proyecto para, por último, ofrecer 

propuestas de mejora. 



7

7. MATERIALES Y ESPACIOS 

En la tabla del apartado 2 se muestran los espacios necesarios para la 

realización de cada sesión de la unidad didáctica, que pueden resumirse en: 

- 4 sesiones en el aula taller, 

- 3 sesiones en el aula de informática, 

- 5 sesiones en un aula de teoría (pudiendo ser la parte habilitada 

para tal fin del aula taller). 

La tabla del apartado 6 muestra los materiales necesarios, con las fichas 

de la unidad a usar en cada sesión. 

8. EVALUACIÓN 

La siguiente tabla muestra los criterios de evaluación y calificación 

Criterios de evaluación 

Conocimiento de los distintos 

mecanismos, su función y 

Criterios de calificación 

Teoría sus leyes fundamentales. 

Revisión de los materiales 

del alumno/a: libreta, fichas... 

Resolución de problemas 

aplicando las leyes y 

20% 

Problemas 

relaciones adecuadas y 

llegando a resultados lógicos. Ponderación 

30% 

Revisión de los materiales de la nota, 

del alumno/a: libreta, fichas... sobre un 

Calidad del modelo realizado total de 10 

(tanto del modelo general, puntos. 

Proyecto 

como de las piezas 

independientes). 

Funcionamiento adecuado 

del modelo. 

Revisión de las fichas de 

25% 

Simulaciones 

informáticas 

actividades propuestas sobre 

las distintas páginas 

visitadas. 

25% 

Para evaluar la parte teórica se realizará una prueba escrita, calificada 

sobre 11 puntos: 10 puntos (contenidos de la materia de Tecnologías) más 1 

punto extra (contenidos lingüísticos), dándose a elegir al alumnado entre 

realizar la prueba: 

- En inglés, de modo que el punto extra involucraría alguna cuestión 

en español, para asegurar que conoce los nombres y las relaciones de 

los distintos mecanismos estudiados. 

- En español, de modo que el punto extra involucraría alguna cuestión 

en inglés, que determine si conoce el vocabulario específico y es capaz 

de emplear construcciones técnicas simples en dicho idioma. 

9. ANEXO: FICHAS 



8

a) GLOSARIO DE TÉRMINOS 

MECHANISM GLOSSARY 

ENGLISH SPANISH 

word phonetics 

(main meaning, in brackets) 

'G1gjUl& 

vI'lAsItI 

velocidad angular 

'Gksl eje 

'bGl&ns equilibrio 

belt correa (cinturón) 

belt Gnd 'pUlIz poleas y correa 

blAk Gnd tackle polipasto (aparejo) 

kGm leva 

'klAkwaIz sentido de las agujas del reloj 

'kaUnt&'klAkwaIz sentido contrario a las agujas del reloj 

'krG1k$@:ft cigüeñal 

krG1k Gnd slaId& biela manivela 

krG1k manivela 

'kr&Ub@: palanca, como elemento 

t$eIn Gnd 

'sprAkIts 

engranajes/piñones con cadena 

'drIvn wi:l rueda conducida 

'draIv& wi:l rueda conductora 

'fAl&U& seguidor 

'frIk$&n wi:lz ruedas de fricción 

spU: 

cilíndrico 

gI& 

'bev&l 

streIt 

engranaje 

cónico (biselado) 

de dientes rectos 

'helIk&l de dientes helicoidales 

gru:v ranura 

gaId guía 

'hGndl mango, asa, tirador 

'aIdl& gI& engranaje loco (holgazán) 

le1(k)T longitud 

'li:v& 

'ef&t 

l&Ud 

@:m 

'pIv&t 

palanca, 

como 

mecanismo 

potencia (esfuerzo) 

resistencia (carga) 

brazo 

punto de apoyo (pivote) 

'lI1kIdZ acoplamiento, articulación 

'mek&nIz&m mecanismo 

'm&Um&nt momento, como magnitud 

'mu:v&bl móvil 

'pUlI polea 

rGk Gnd 'pInj&n piñón cremallera 

rGmp rampa, plano inclinado 

'reI$I&U razón, relación 

r&Up cuerda 



9

skru: tornillo 

$@:ft eje 




spi:d &v 

velocidad de rotación 

r&U'teI$&n 

spu:l carrete 

Tred rosca, filete (hilo) 

t& &'plaI aplicar 

t& &'sembl ensamblar 

t& &'tGt$ acoplar 

t& t$eIn encadenar 

t& hG1 colgar 

t& h&Uld sujetar, sostener, suspender 

t& dZ%In unir, juntar 

t& lIft levantar 

t& me$ engranar (malla, red) 

t& rI'vAlv girar 

t& r&Ul hacer rodar 

t& r&U'teIt rotar 

t& slaId deslizar, resbalar 

t& slIp resbalar 

t& tU:n girar 

treIn &v 

'mek&nIz&m 

tren de mecanismos 

vI'lAsItI 

relación de transmisión 

'reI$I&U 

wedZ cuña 

weIt peso 

wi:l rueda, volante 

wInt$ torno, cabestrante 

wU:m Gnd 

wU:mwi:l 

tornillo sinfín corona (gusano) 



10

MECHANISM GLOSSARY 




angular velocity 

'G1gjUl& 

vI'lAsItI 

velocidad angular 

axle 'Gksl eje 

balance 'bGl&ns equilibrio 

belt belt correa (cinturón) 

belts and pulleys belt Gnd 'pUlIz poleas y correa 

block and tackle blAk Gnd tackle polipasto (aparejo) 

cam kGm leva 

clockwise 'klAkwaIz sentido de las agujas del reloj 

counter-clockwise 'kaUnt&'klAkwaIz sentido contrario a las agujas del reloj 

crankshaft 'krG1k$@:ft cigüeñal 

crank and slider krG1k Gnd slaId& biela manivela 

crank krG1k manivela 

crowbar 'kr&Ub@: palanca, como elemento 

chain and sprockets 

t$eIn Gnd 

'sprAkIts 

engranajes/piñones con cadena 

driven wheel 'drIvn wi:l rueda conducida 

driver wheel 'draIv& wi:l rueda conductora 

follower 'fAl&U& seguidor 

friction wheels 'frIk$&n wi:lz ruedas de fricción 

spur gear 

spU: 

cilíndrico 

gear 

bevel gear 

straight gear 

gI& 

'bev&l 

streIt 

engranaje 

cónico (biselado) 

de dientes rectos 

helical gear 'helIk&l de dientes helicoidales 

groove gru:v ranura 

guide gaId guía 

handle 'hGndl mango, asa, tirador 

idler gear 'aIdl& gI& engranaje loco (holgazán) 

length le1(k)T longitud 

lever 

effort 

load 

arm 

pivot 

'li:v& 

'ef&t 

l&Ud 

@:m 

'pIv&t 

palanca, 

como 

mecanismo 

potencia (esfuerzo) 

resistencia (carga) 

brazo 

punto de apoyo (pivote) 

linkage 'lI1kIdZ acoplamiento, articulación 

mechanism 'mek&nIz&m mecanismo 

moment 'm&Um&nt momento, como magnitud 

movable 'mu:v&bl móvil 

pulley 'pUlI polea 

rack and pinion rGk Gnd 'pInj&n piñón cremallera 

ramp rGmp rampa, plano inclinado 

ratio 'reI$I&U razón, relación 

rope r&Up cuerda 

screw skru: tornillo 



11

shaft $@:ft eje 




speed of rotation 

spi:d &v 

r&U'teI$&n 

velocidad de rotación 

spool spu:l carrete 

thread Tred rosca, filete (hilo) 

to apply t& &'plaI aplicar 

to assemble t& &'sembl ensamblar 

to attach t& &'tGt$ acoplar 

to chain (up) t& t$eIn encadenar 

to hang (up) t& hG1 colgar 

to hold (up) t& h&Uld sujetar, sostener, suspender 

to join t& dZ%In unir, juntar 

to lift (up) t& lIft levantar 

to mesh (with) t& me$ engranar (malla, red) 

to revolve (at) t& rI'vAlv girar 

to roll t& r&Ul hacer rodar 

to rotate t& r&U'teIt rotar 

to slide t& slaId deslizar, resbalar 

to slip t& slIp resbalar 

to turn t& tU:n girar 

train of mechanism 

treIn &v 

'mek&nIz&m 

tren de mecanismos 

velocity ratio 

vI'lAsItI 

'reI$I&U 

relación de transmisión 

wedge wedZ cuña 

weight weIt peso 

wheel wi:l rueda, volante 

winch wInt$ torno, cabestrante 

worm and wormwheel 

wU:m Gnd 

wU:mwi:l 

tornillo sinfín corona (gusano) 



12

) FICHAS DE TEORÍA 

SIMPLE MACHINES --------------------------------------------------------------------------------------------- 14 

• LEVERS ------------------------------------------------------------------------------------------------------ 14 

• PULLEYS ---------------------------------------------------------------------------------------------------- 17 

ROTARY SYSTEMS --------------------------------------------------------------------------------------------- 19 

• FRICTION WHEELS --------------------------------------------------------------------------------------- 19 

• BELT AND PULLEYS -------------------------------------------------------------------------------------- 20 

• GEARS ------------------------------------------------------------------------------------------------------- 20 

• CHAINS AND SPROCKETS ------------------------------------------------------------------------------ 20 

• WORM AND WORMWHEEL ----------------------------------------------------------------------------- 22 

• RACK AND PINION --------------------------------------------------------------------------------------- 22 

OTHER MECANISMS ------------------------------------------------------------------------------------------- 22 

• CRANK ------------------------------------------------------------------------------------------------------- 22 

• CAMS --------------------------------------------------------------------------------------------------------- 23 

TRAINS OF MECANISMS -------------------------------------------------------------------------------------- 23 

• GEAR TRAIN ------------------------------------------------------------------------------------------------ 24 

COMMENTS --------------------------------------------------------------------------------------------- 24 

UNITS ----------------------------------------------------------------------------------------------------- 24 



13

MECHANISMS 

In technology, we define mechanisms as elements that transmit and/or 

transform forces and/or motion from a driver element to a driven element. 

A machine is any object that transforms or transmits energy, making the 

work easier. Ancient Greeks talked about five simple machines: the lever, 

inclined plane (ramp), wheel and axle, pulley, screw and wedge. 

We are going to study the main mechanisms that we can find in lots of 

machines. 

SIMPLE MACHINES 

• LEVERS 

A lever is a rigid bar that turns around a fixed point called fulcrum (or 

pivot). We often use a lever to move a load with a smaller effort. Any lever has 

three parts: 

- Fulcrum/pivot: the fixed point where the lever turns. 

- Effort force: the force done by the user (the input force). 

- Load: the force done by the element being acted on (the output force). 

The picture above shows the lever diagram which we are going to use to 

study levers and their types. There are three different kinds of levers according 

to the relative position of these three parts: 

Name Definition Symbol Example 

First-class 

lever: 

Second-class 

lever: 

Third-class 

lever: 

load force 

lever 

The pivot is placed 

between the effort 

and the load 

The load is placed 

between the effort 

and the pivot 

The effort is 

placed between 

the pivot and the 

load 

fulcrum/pivot 



effort force 

seesaw 

scissors 

handcart 

tweezers 

14

Two forces 

Two distances 

(called arms) 

There are four main magnitudes in a lever (we have already seen two of 

them): 

Effort force: the force we are applying (Feffort/Fe). 

Effort arm: the distance from the pivot to the effort (deffort/de). 

Load force: the force that is the result of the force applied 

(Fload/Fl). 

Load arm: the distance from the pivot to the load (dload/dl). 

Fload 

load 

Feffort 

effort 

deffort 



dload 

fulcrum 

The lever length (l) can be calculated using its arm distances: 

l = d + d . 

1 st class lever: e l 

2 nd class lever: de 

l = , so deffort>dload. 

3 rd class lever: l d l = , so deffort

with this equation we can achieve the following conclusions: 

Name Arm ratio Conclusion 

1 st class lever: 

deffort 

If d load > deffort 

< 1 Fload 

< Feffort 

dload 

deffort 

If d effort > dload 

> 1 Fload 

> Feffort 

dload 

The effort is 

less than the 

load. 

The effort is 

greater than the 

load. 

2 nd class lever: 

deffort 

d effort > dload 

> 1 Fload 

dload 

> Feffort 

The effort is 

always less than 

the load. 

3 rd class lever: 

deffort 

d load > deffort 

< 1 Fload 

dload 

< Feffort 

The effort is 

always greater 

than the load. 

The product of a force and its lever arm is a new magnitude called 

moment (M), so we can rewrite the law of a lever: 

M = 

effort 

We can join levers making a compound system. The load force in one 

lever will be the effort force to the next one. So we can work forces out step by 

step, noticing where the new pivot is placed. 

load 



M 

Archimedes said: 

“Give me a place to stand on, 

and I will move the earth” 

16

• PULLEYS 

A pulley is a wheel with a groove all around its perimeter that allows us to 

place a rope/belt around it. This wheel can turn around its centre (axle) because 

of the rope motion. We often use pulleys to lift weights easier. 

There are four main magnitudes in a pulley (two forces and two 

distances): 

Effort: the force we are applying (F). 

Load: the weight we are lifting (L). 

Effort length: the distance moved by effort (l). 

Load height: the distance moved by load (h). 

The following pictures show the pulley diagrams which we will use to 

study pulleys and their types. 

rope length 

l 

effort 

F 

axle 

pulley 

rope 

load 

L 

Fixed pulley 

load height 

h 

effort 



load 

Movable pulley 

effort 

There are fixed and movable pulleys. A fixed pulley has got a fixed axle; a 

movable pulley has got a hanging axle, so it can move. The pictures above 

show single pulleys. Normally we don’t use single movable pulleys but rather 

two pulleys, a fixed pulley and a movable pulley, which are called compound 

pulleys. We can find pulley systems too. 

The table below shows some kind of pulleys and their equations: 

17

Single pulley 

Name Picture Equations 

Compound pulley 

(movable pulley) 


(block and tackle) 

The movable pulleys are 

all joined together. 


The pulleys are 

chained to each other. 



F 

F 

F 

F 

L 

L 

L 

L 

F = L 

l = h 

L 

F = 

2 

l = 2⋅ 

h 

L 

F = 

2 ⋅n 

l = 2⋅ 

n ⋅h 

n: number of movable pulleys 

L 

F = n 

2 

n 

l = 2 ⋅ h 

n: number of movable pulleys 

18

ROTARY SYSTEMS 

These systems transmit motion or forces from one shaft (axle) to another. 

First we are going to study only systems with two elements. After that we will 

talk about mechanism trains as well. 

• FRICTION WHEELS 

They are wheels joined through friction. The driver wheel transmits 

motion to the driven wheel by rolling, but both wheels turn in opposite directions. 

We can draw 

them in two ways. 

driver 

driven 



w1 

d1 

w2 

d2 

driver shaft driven shaft 

There are four main magnitudes in this system, two speeds and two 

distances (they could be diameters or radius): 

Driver wheel speed of rotation/angular velocity (w1). 

Driver wheel diameter (d1). 

Driven wheel speed of rotation/angular velocity (w2). 

Driven wheel diameter (d2). 

We can write the main relationship between them in two ways or 

equations: 

Velocity ratio: 

Speed of rotation increases. 

Speed of rotation doesn’t change. 

Speed of rotation decreases. 

(Remark: some people swap the magnitudes in this ratio, so i>1 

means speed decreases and i

Fundamental law: 

• BELT AND PULLEYS 

They are pulleys joined through a rope, called belt. The belt transmits the 

motion from driver pulley to driven pulley, so both pulleys turn in the same 

direction (unless the belt is crossed). 

The magnitudes and the equations are the same as in the previous 

mechanism, but the wheels are called pulleys. 

• GEARS 

A gear is a toothed wheel, so we can join gears assembling their teeth 

(this is called two meshed gears). They work as friction wheels, but the teeth 

prevent the wheels from slipping. 

The magnitudes and the equations are the same as in the previous 

mechanism, swapping diameters for number of teeth, but they turn in opposite 

directions: 

Driver gear speed of rotation (w1). 

Number of teeth on the driver gear (n1). 

Driven gear speed of rotation (w2). 

Number of teeth on the driven gear (n2). 

Velocity ratio/gear ratio: 

Fundamental law of gear action: 

There are many different types of gears according to gear and teeth 

shapes. So they can work with parallel shafts, perpendicular shafts or even 

shafts in different angles: 

- Spur gears: they connect parallel shafts. 

- Bevel gears: they connect nonparallel shafts. 

- Straight gears: they have straight teeth. 

- Helical gears: they haven’t got straight teeth. 

• CHAINS AND SPROCKETS 


Technology - ESO 

bevel gears 

20

A sprocket is a gear driven by a chain. It works in the same way as belts 

and pulleys do, but its strength is greater, and like gears, it doesn’t slide. It has 

the same equations as gears, but they turn in the same direction. 



21

• WORM AND WORMWHEEL 

A worm is a screw with one or more inputs, which drives a gear called 

wormwheel. They have nonparallel shafts. 

We can apply the same equations as gears, but swapping number of 

teeth for number of worm gear threads (usually one): 


Fundamental law: 

• RACK AND PINION 

A rack and a pinion are both gears, but the rack has an infinite diameter, 

that means it is a toothed bar, a linear gear. This mechanism changes rotary 

motion into linear motion or vice versa. We are not going to study the equations 

of its motion. 

OTHER MECANISMS 

• CRANK 

A crank is a bar attached to an axle around which it turns. Sometimes, we 

can find it working as a handle in mechanical devices or being part of a 

compound mechanism. It has lots of uses; we are going to see some of them: 

Winch: It is a drum or spool whose axle is joined to a crank. The winch 

drum has a rope winding around it, which allows weights to be lifted 

more easily. An example: the mechanism to draw water from a well. 

Using the following magnitudes: 

- winch drum radius (r). 

- crank length (d). 

- load (L). 

- effort (F). 

the equation of a winch will be: 



22

Crank and slider: In this case, the crank drives the motion of another 

bar called slider. The slider moves another element (for example, a 

piston) inside a guide. This mechanism converts reciprocating linear 

motion into rotating motion (or vice versa). 

equation 

Crankshaft: We can use some slider-crank mechanisms working 

together, joined with a bent shaft called crankshaft. It can change 

reciprocating motion into rotary motion by attaching pistons to the 

crankshaft. An example: the mechanism that moves the pistons of a car. 

• CAMS 

A cam is a rotary element, which can have different shapes, linked with a 

bar, called follower. When the cam rotates, the follower moves forward and 

backwards, up and down, left-hand side and right-hand side… in a way 

depending on cam shape. This mechanism transforms rotary motion into linear 

motion. 

TRAINS OF MECANISMS 

We can join equal mechanisms, attached by their shafts. If we join belt 

and pulleys, we will have a belt and pulleys train. If we mesh gears, we will have 

a gear train. Even we can join different types of mechanism. 

We can work with a train in the same way as with a simple mechanism, 

working out velocity ratios and applying fundamental laws, step by step, noticing 

that: 

All the mechanisms attached to the same shaft 

revolve at the same speed. 

In order to clarify this, an example with gears is shown below. 



23

• GEAR TRAIN 

Given the following gear train, we are going to get the main equations. 

We can only apply the transmission equations to those elements joined 

by some kind of transmission mechanism. Elements attached to the same axle 

are not joined as a transmission system, so we can’t apply the equations we 

have studied. 

Gears 2 and 3 are joined by shaft so: . 

Fundamental law of gear action: 

between gears 1 and 2: , 

between gears 3 and 4: , 

notice: we don’t apply this law with gears 2 and 3. 


between gears 1 and 2, 

- using speed of rotation: , 

- using number of teeth: , 

between gears 3 and 4, 

- using speed of rotation: , 

- using number of teeth: , 

Notice that we don’t figure out velocity ratio with gears 2 and 3. 

We can study the system as a whole and work out its gear ratio by 

multiplying the velocity ratio of each pair of gears. So using: 

- speeds of rotation: ; 

- velocity ratios: , but here we can’t reduce the equation. 

COMMENTS 

1) In first class levers, if the pivot is nearer to the load than to the effort, 

the effort force will be smaller. 

2) In simple rotary systems, the smaller the wheel the higher the speed. 

3) Gears don’t slip and transmit higher forces, but they are noisier and 

more expensive than belt and pulleys and friction pulleys. 

4) In rotary systems, if the distance between the shafts is long, we will use 

belt and pulleys system. 

UNITS 

We have talked about different magnitudes, now we are going to talk 

about their measurement in our exercises. 

Term Unit Symbol Relationship 



24

Force Newton N 

Kil Kg 

ogr(kp 

am ) 

(kil 

op 

on 

d) 

Distance 

Diameter 

Radius 

Speed of rotation 

Angular velocity 

Radians 

per 

second 

MoNe 

N. 

mewt 

m 

nt on 

me 

ter 

rad/s 

Meter, 

and its multiples 

Velocity ratio — 

Revolutions per 

minute 



m 

rpm 

25

c) FICHAS DE PROBLEMAS 

EXERCISE 1 ----------------------------------------------------------------------------------------------------------- 27 

EXERCISE 2 ----------------------------------------------------------------------------------------------------------- 27 

EXERCISE 3 ----------------------------------------------------------------------------------------------------------- 27 

EXERCISE 4 ----------------------------------------------------------------------------------------------------------- 27 

EXERCISE 5 ----------------------------------------------------------------------------------------------------------- 28 

EXERCISE 6 ----------------------------------------------------------------------------------------------------------- 28 

EXERCISE 7 ----------------------------------------------------------------------------------------------------------- 28 

EXERCISE 8 ----------------------------------------------------------------------------------------------------------- 29 

EXERCISE 9 ----------------------------------------------------------------------------------------------------------- 29 

EXERCISE 10 --------------------------------------------------------------------------------------------------------- 29 

EXERCISE 11 --------------------------------------------------------------------------------------------------------- 29 

EXERCISE 12 --------------------------------------------------------------------------------------------------------- 29 

EXERCISE 13 --------------------------------------------------------------------------------------------------------- 30 

EXERCISE 14 --------------------------------------------------------------------------------------------------------- 30 

EXERCISE 15 --------------------------------------------------------------------------------------------------------- 30 

EXERCISE 16 --------------------------------------------------------------------------------------------------------- 30 

EXERCISE 17 --------------------------------------------------------------------------------------------------------- 30 

EXERCISE 18 --------------------------------------------------------------------------------------------------------- 30 

EXERCISE 19 --------------------------------------------------------------------------------------------------------- 30 

EXERCISE 20 --------------------------------------------------------------------------------------------------------- 31 

EXERCISE 21 --------------------------------------------------------------------------------------------------------- 31 

EXERCISE 22 --------------------------------------------------------------------------------------------------------- 31 



26

MECHANISMS EXERCISES 

EXERCISE 1: A man wants to lift a stone with a 7m length crowbar. The stone 

weights 150Kg and it is 2m from the pivot. Draw the diagram of the mechanism, 

showing its elements, and work out the effort force needed by the man. 

EXERCISE 2: We have a handcart where distance from the handle to the wheel 

is 1.5m and distance from the wheel to the load is 0.3m. We want to move a 

90Kg weight. Draw the diagram of the mechanism, showing its elements, and 

work out the effort force we need to apply. 

EXERCISE 3: The following picture shows a lever. With the values given, 

answer the following questions: 

(a) What kind of lever is shown in the picture? 

(b) What effort force do you need to lift the load? 

(c) What is the length of the lever? 

(d) What problem has it got? 

EXERCISE 4: Complete the following table with the values needed to balance a 

1 st class lever: 

Eff 

ort 

for 

ce 

Eff 

ort 

ar 

m 

40 60 

0g cm 

75 50 

0N cm 

15 

0k 

g 

20 

0c 

m 

Lo 

ad 

for 

ce 

Lo 

ad 

ar 

m 

50 

cm 

12 1m 

0k 

g 

30 3m 

Kg 

Le 

ver 

len 

gth 

12 

5c 

m 

600N 30cm 20N 



27

EXERCISE 5: In the following pictures of compound levers, write the type of 

each lever and figure out the effort forces. 

EXERCISE 6: You want to lift a 60Kg weight with a single pulley. What effort 

force do you need to apply? If you want to move it 8m up, what length of rope do 

you need to pull in? 

EXERCISE 7: With the mechanism of the picture. 

(a) Write the name of each pulley. 

(b) If we want to lift the weight half a meter, what length of rope do we need 

to pull in? 

(c) If the load weights 120kg, figure out the effort force needed to lift it. 



28

EXERCISE 8: According to the pictures below, answer the following questions 

for each mechanism: 

(a) How many pulleys has the mechanism got? How many pulleys are fixed 

pulleys? How many pulleys are movable pulleys? 

(b) What effort force does a man need to lift a 180kg stone 3m up? 

(c) What length of rope does he need to pull in? 

(d) If the man pulls in 3m of rope in 2 seconds, at what speed does the 

stone go up? 

EXERCISE 9: Draw a compound pulley as shown in picture 1 in exercise 8, but 

with two fixed pulleys and two movable pulleys. What effort force would you 

need to lift a 100kg weight? What length of rope would it pull in to lift the weight 

2m up? 

EXERCISE 10: Draw a compound pulley as shown in picture 2 in exercise 8, but 

with three movable pulleys. What effort force would you need to lift a 400kg 

weight? What length of rope would it take in to lift the weight 1.5m up? 

Picture 1 

Picture 2 

EXERCISE 11: With this exercise we are going to understand why we have 

different effort forces with different compound systems. Look at the systems and 

try to guess their effort force by doing a force balance (figure it out with a load of 

120N). This means you need to share the weight among the ropes that are 

holding up the weight. First of all, do a force balance with compound pulleys on 

exercises 7 and 8. 

Picture 1 Picture 2 Picture 3 

EXERCISE 12: Write the name of the following mechanisms. Work out the 

missing magnitude of each driven wheel and the velocity ratio of each 

mechanism. Draw an arrow in the direction of the driven wheel. 

Picture 1 

Picture 2 

Picture 3 



29

EXERCISE 13: The following picture shows a column drill internal mechanism. It 

has two cones of pulleys joined with a belt. Figure out the three possible angular 

velocities in the output cone, by moving the belt to one pair of pulleys to 

another, if the motor speed of rotation is 500rpm. 

EXERCISE 14: Draw a worm and wormwheel. If the wormwheel has 50 teeth 

and the worm revolves at 5000rpm, figure out the velocity ratio and the 

wormwheel speed of rotation when the worm has: 

a) One thread. 

b) Two threads. 

EXERCISE 15: Figure out the diameter of a winch that allows lift a 10kg weight. 

The crank length is 80cm and the effort force on it is 5N. Draw the mechanism 

diagram. 

EXERCISE 16: Look at the picture and answer the questions: 

a) What kind of mechanism does the picture show? 

b) Work out the effort force. 

c) If the load is doubled, work out the new effort force. 

EXERCISE 17: Figure out the output speed and the gear ratio of the following 

gear train. Draw an arrow showing each gear direction. 

If the driver gear was gear 2 (and w2=300rpm counter-clockwise), work 

out the speed of rotation of each gear. Draw their directions with an arrow. 

EXERCISE 18: Figure out the output speed and the gear ratio of the following 

gear train. Draw an arrow showing each gear direction. 

Take away the gear number 4 and mesh gears 3 and 5. Figure out the 

driven gear speed of rotation. 

The gear number 4 is called idler gear, what is it function in a gear train? 

EXERCISE 19: Look at the following belts and pulleys train and answer the 

following questions. All the diameters are given. 

a) How many shafts has the train got? 

b) What pulleys are rotating at the same speed? 

c) If the driver pulley is connected to a motor that revolves at 100rpm, 

figure out the speed of rotation of the other pulleys. Draw the arrows 

of direction if the motor turns clockwise. 



30

d) If we swap the motor and connect it to the pulley number 4, revolving 

at 200rpm, figure out the seed of rotation of the other pulleys. Draw 

the arrows of direction if the motor turns counter-clockwise. 

EXERCISE 20: With the following compound mechanism: 

a) Write the name of each mechanism. 

b) Figure out the speed of rotation of each shaft if we connect a motor, 

revolving at 100rpm, to: 

1st.- Shaft I. 

2nd.- Shaft II. 

3rd.- Shaft III. 

4th.- Shaft IV. 

EXERCISE 21: Work out w2, w3 and velocity ratios in the following mechanism. 

EXERCISE 22: Solve completely the following mechanism (speed of rotations 

and velocity ratios). 



31

d) FICHAS DE ACTIVIDADES PARA EL AULA DE INFORMÁTICA 

http://flying-pig.co.uk/mechanism/index.html ------------------------------------------------------------------ 33 

ACTIVITY 1 ------------------------------------------------------------------------------------------------ 33 

ACTIVITY 2 ------------------------------------------------------------------------------------------------ 35 

ACTIVITY 3 ------------------------------------------------------------------------------------------------ 37 

ACTIVITY 4 ------------------------------------------------------------------------------------------------ 38 

ACTIVITY 5 ------------------------------------------------------------------------------------------------ 40 

ACTIVITY 6 ------------------------------------------------------------------------------------------------ 41 

ACTIVITY 7 ------------------------------------------------------------------------------------------------ 43 

ACTIVITY 8 ------------------------------------------------------------------------------------------------ 43 

ACTIVITY 9 ------------------------------------------------------------------------------------------------ 43 

ACTIVITY 10 ----------------------------------------------------------------------------------------------- 45 

http://www.technologystudent.com/index.htm ----------------------------------------------------------------- 46 

Pulleys --------------------------------------------------------------------------------------------------------------- 46 

ACTIVITY 1 ------------------------------------------------------------------------------------------------ 46 

ACTIVITY 2 ------------------------------------------------------------------------------------------------ 46 

ACTIVITY 3 ------------------------------------------------------------------------------------------------ 46 

ACTIVITY 4 ------------------------------------------------------------------------------------------------ 49 

ACTIVITY 5 ------------------------------------------------------------------------------------------------ 51 

Gears ---------------------------------------------------------------------------------------------------------------- 51 

ACTIVITY 6 ------------------------------------------------------------------------------------------------ 52 

ACTIVITY 7 ------------------------------------------------------------------------------------------------ 54 

ACTIVITY 8 ------------------------------------------------------------------------------------------------ 54 

ACTIVITY 9 ------------------------------------------------------------------------------------------------ 54 

Cams and followers ------------------------------------------------------------------------------------------------ 54 

ACTIVITY 10 ----------------------------------------------------------------------------------------------- 54 

ACTIVITY 11 ----------------------------------------------------------------------------------------------- 55 

ACTIVITY 12 ----------------------------------------------------------------------------------------------- 56 

Other mechanisms ------------------------------------------------------------------------------------------------- 58 

ACTIVITY 13 ----------------------------------------------------------------------------------------------- 58 

ACTIVITY 14 ----------------------------------------------------------------------------------------------- 63 



32

ICT ACTIVITIES 

We are going to work with two websites. 

Visit them and do the activities in each one. 

First website 

http://flying-pig.co.uk/mechanism/index.html 

ACTIVITY 1: Complete the following table with the most important types of 

motion and some of their properties. Write the English name below the Spanish 

one (on non-continuous line). Draw the motion arrow shown in the website after 

the motion definition (inside de square). 

Spanish name: Definition: Properties: 

Movimiento de rotación 

Movimiento lineal 

Movimiento 

intermitente 

Movimiento alternativo 

Movimiento 

oscilatorio 

Mo 

vi 

frequency 

Us 

uall 

y 

cre 

Term:Definition: 



amplitude 

periodic time 

Term: Measurement: 

The velocity 

is measured 

in two parts: 

rpm 

clockwise 

anti-clockwise 

Newton.meter 

(N.m) 

Term: Definition: 

throw 

period 

33

mi 

ent 

o 

irre 

gul 

ar 

ate 

d 

usi 

ng: 



34

ACTIVITY 2: Complete the table with the mechanisms we can use to turn one 

motion into another one. 

Conversions: Mechanisms: Spanish 

name: 

linear motion to rotary motion 

rotary motion to linear motion 

rec 

ipr 

oc 

ati 

ng 

mo 

tio 

n 

to 

int 

er 

mit 

ten 

t 

mo 

tio 

n 

rot 

ary 

mo 

tio 

n 

reciprocating motion 

oscillation 

oscillation reciprocating 

to motion 

oscillation 

intermittent 

motion 



35

irregular 

motion 

rotary motion 

intermittent motion 



36

ACTIVITY 3: Look at the pictures and complete the information required. 

Mechanism name (picture 1): 

(a) Write the element names near the lines (picture 1). 

(b) Complete the following sentence: “As the _______________ turns, 

driven by the _______________ motion, the _______________ 

_______________ traces the surface of the _______________ transmitting 

its motion to the required _______________.” 

(c) In cam follower design, what two things are important in order to achieve 

a more accurate movement? 

picture 1 

Mechanism name (pictures 3, 4 and 5): 



(d) Explain the hen follower 

motion when the cam turns once. 

picture 2 

(a) Fill in the table, selecting the lever order of each picture and writing why 

you have chosen that order. Give an example of each type into the last row. 

1 st 

- 

2 nd 

- 

3 rd 

ord 

er 

ex 

am 

ple 

s 

1 st 

- 

2 nd 

- 

3 rd 

3 rd 

ord 

er 

picture 3 picture 4 picture 5 

1 st 

- 

2 nd 

- 

ord 

er 

37

(b) Complete the following sentence: “With this mechanism we can change the 

_______________, the _______________ and the _______________ of the 

movement.” 

(c) Why are the arrow widths different in each picture? 

(d) In picture 3, with the force _______________times closer to the fulcrum the 

load lifted is only ________ ________ of the force but it moves 

_______________ times as far. 

Mechanism name (picture 6): 

picture 6 

(a) Write in the picture the name of each element, defining each one. 

(b) What determines the speed of the mechanism? 

(c) Explain how we use this mechanism in the following systems: 

The steering system of cars. 

The rack and pinion railway. 

ACTIVITY 4: Write the names of the following mechanisms and their 

differences: 

N 

am 

e: 

A 

bo 

ut 

the 

rop 

e 

pul 

led 

: 

Name: 

 

Ab 

out 

the 

rop 

e 

pul 

led 

About the weight: 



38

: 

 

Ab 

out 

the 

we 

igh 

t: 



39

ACTIVITY 5: Looking at the pictures, write each mechanism name and its 

function. 

English name: 

Spanish name: 

Function: 

English 

name: 

Spanish 

name: 

English 

name: 

Spanish 

name: 

Function: Function: Function: 

English name: 

Spanish name: 

Function: 

English 

name: 

Spanish 

name: 

English name: 

Spanish name: 

Function: 

English name: 

Spanish name: 

Function: 



English name: 

Spanish name: 

Function: 

English name: 

Spanish name: 

Function: 

40

ACTIVITY 6: Girolamo Cardano invented different mechanisms that we still use 

nowadays. One of them is given in this website. Identify it and search about it to 

do a document with the following information and format, using Microsoft Word. 

You will need to visit other websites in order the complete the whole information 

A 

bo 

ut 

Gi 

rol 

a 

m 

o 

Ca 

rd 

an 

o 

About 

mechanism 

Me 

ch 

ani 

sm 

na 

me 

Ca Ca 

rda rda 

n n 

ge joi 

ar nt 

Cardano biography Cardano picture 



41

(struni 

aig ver 

ht sal 

lin joi 

e nt 

mo 

tio 

n) 

Me 

ch 

ani 

sm 

pic 

tur 

e 

Explanation about how the mechanism works 



42

ACTIVITY 7: Look at this mechanism and complete the sentences with the 

website information. 

geared reciprocating motion 

(a) This mechanism is used to convert between _______________ motion and 

_______________ motion, as the _______________ does. 

(b) Comparing this mechanism with a _______________, in the mechanism of 

the picture the straight line motion stays at a _______________ 

_______________; but in a _______________ the _______________ 

changes, reaching maximum value in the _______________ of its travel. 

(c) Why do we call this motion “geared reciprocating motion”? 

ACTIVITY 8: In this activity we will talk about linkages ( _______________ in 

Spanish) that are an essential part of any mechanisms. They can be used to: 

1.- 

2.- 

3.- 

The website develops the basic four bar linkage. All four bars make up a 

_______________. We can achieve different movements by changing: 

Try to locate in the picture: 

1.- The bars or shafts (draw 

arrows). 

2.- The 

linkages 

or 



junctions 

draw 

circles). 

In each box, draw the linkage that matches with the definition: 

Definition: Picture 

Two against two equal length 

shafts: 

Only two equal length shafts: 

All bar with different lengths: 

ACTIVITY 9: Complete the following sentences: 

43

Gears: 

(a) Gears are used to . 

(b) With two gears and looking at the direction, one of them turns 

and the other one turns 

directions. 

. So gears turn in 

(c) With two gears with different size: the 

the speed. 

the gear, the 

(d) A ring of gears need to contain an number of gears to 

turn . If the ring had an number of gears, 

the gears would together. 

Belt and pulleys (belt drives): 

(a) Belt drives are used to transfer rotational motion from one 

another. 

to 

(b) With two pulleys with the same size, the of 

doesn’t change, we would need two sizes of pulley. 

(c) By the belt the direction of drive can be changed. 

(d) Underline the correct work in the table below: 

Both pulleys turn in the same / different 

directions. 

Both pulleys Both pulleys Both pulleys 

turn at the turn at the turn at the 

same/different same/different same/different 

speed. speed. speed. 

Ri Ri Ri 

ght ght ght 

pul pul pul 

ley ley ley 

rev rev rev 

olv olv olv 

es es es 

at at at 

a a a 

hig hig hig 

her her her 

/lo /lo /lo 

we we we 

r/s r/s r/s 

am am am 

e e e 

sp sp sp 

ee ee ee 

d. d. d. 



Both pulleys 

turn in the 

same / 

different 

directions. 

Both pulleys 

turn in the 

same / 

different 

directions. 

44

ACTIVITY 10: Now we will see some compound mechanism. Write the name of 

the mechanisms and their main pieces (arrows). You must write Spanish and 

English names of mechanisms and their pieces. You will find two boxes with the 

piece names at the end of the exercise. 

English mechanism name: 

Spanish 

mechanism 

name: 


Spanish mechanism name: 

En 

gli 

sh 

me 

ch 

ani 

sm 

na 

me 

: 

Spanish mechanism name: 


Spanish 

mechanism 

name: 

palletes - displacement cylinder - fly wheel - steam - lever - escape wheel 

chamber - rod - teeth - exhaust - cranck - heat source - second sealed piston 

cam/oval crank - balance wheel - displacement piston - hairspring 

Mechanisms Unidad didáctica main cylinder - fins/cool finned - piston - control valve 


45

Pulleys 

Second website 

http://www.technologystudent.com/index.htm 

ACTIVITY 1: Complete the belt and pulleys system explanation and the table 

with the names (English and Spanish names): 

“Pulley wheels are __________ so that the __________ cannot slip 

off. Also, the __________ is pulled tight between the two pulleys 

wheels (in __________ ). The __________ caused by this means 

that when the __________ rotates the __________ follows 

ACTIVITY 2: Write the English and Spanish names: 

ACTIVITY 3: Complete the following table using what we have learnt in our 

class. 

winch rope 

Picture 



Velocity ratio 


(method two: 

(method one: 

using speeds of 

using diameters) 

belt and pulleys system 

rotation) 

This means that the driver/driven pulley wheel (the larger/smaller pulley wheel) 

revolves faster than the _____ pulley wheel (the _____ pulley wheel). So for 

every single revolution of the larger driven pulley wheel, the smaller driver 

wheel rotates ___ times. 

If the driver pulley turns clockwise, the driven pulley will turn __________. 

Thi 

s 

me 

an 

s 

tha 

t 

the 

__ 

motor 

winch 

46

__ 

_ 

pul 

ley 

wh 

eel 

(th 

e 

__ 

__ 

_ 

pul 

ley 

wh 

eel 

) 

rev 

olv 

es 

slo 

we 

r 

tha 

n 

the 

__ 

__ 

_ 

pul 

ley 

wh 

eel 

(th 

e 

__ 

__ 

_ 

pul 

ley 

wh 

eel 

). 

So 

for 

ev 

ery 

sin 

gle 

rev 

olu 



47

tio 

n 

of 

the 

lar 

ger 

dri 

ver 

pul 

ley 

wh 

eel 

, 

the 

sm 

all 

er 

dri 

ver 

pul 

ley 

wh 

eel 

rot 

ate 

s 

__ 

_ 

tim 

es. 

If 

the 

dri 

ver 

pul 

ley 

tur 

ns 

clo 

ck 

wis 

e, 

the 

dri 

ve 

n 

pul 

ley 

will 

tur 



48

n 

__ 

__ 

__ 

__ 

__. 

This means that the _____ pulley wheel (the _____ pulley wheel) revolves 

faster than the _____ pulley wheel (the _____ pulley wheel). So for every single 

revolution of the larger driven pulley wheel, the smaller driver wheel rotates ___ 

times. 

If the driver pulley turns clockwise, the driven pulley will turn __________. 

ACTIVITY 4: When using pulleys for lifting, the formulas for mechanical 

advantage and velocity ratio are very important; fill in the triangles that help us to 

work them out, complete the sentences and write the equations asked. 

Load distance 

(L) = mover 

by load 

(dL) = 

Formulas: Formulas: 



Mechanical 

advantage is 

defined as the 

ratio of _____ to 

____. 

Velocity ratio (or 

movement ratio) 

is defined as the 

ratio of the 

__________ 

moved by the 

_____ to the 

__________ 

moved by the 

______. 

mechanical advantage (MA) = velocity/movement ratio (VR) = 

49

Effort (E) = distance mover by effort (dE) = 



50

ACTIVITY 5: Complete the table and the sentences. 

Gears 

mechanical 

advantage 

= 

velocity 

ratio = 

number of 

movable 

pulleys = 

Picture 



Mechanical advantage 


mechanical advantage = 

velocity ratio = 



number of movable pulleys = 



number of movable pulleys = 

(a)We can compare a single pulley with a __________. 

(b)100% efficiency is only theoretical. No pulley system is 100% 

efficient. This is due to __________. 

51

ACTIVITY 6: Write the names of gear elements near the arrows and complete 

the boxes information. After that, try to match Spanish and English names in the 

last table. 

It is the _________ part of 

a gear wheel. 

This circle shows 

the _____ limit of 

the teeth. 

pitch 

point 

It is the point where gear teeth 

actually make ________ each 

other as they ________. 

center 

distance 

This circle is used to determine the 

_____ of the teeth and the _____ 

between gears. 

radio 

del 

pie 

paso 

English 

name 



Spanish name 

root radio 

primitivo 

pitch punto 

circles de 

engrane 

It is the __________ 

between any point on one 

_____ and the same point 

on the next _____. 

52



53

ACTIVITY 7: Looking at the following picture, answer the questions: 

a) The picture shows ______________________________. 

b) If gear A turns clockwise direction, draw arrows in the picture showing the 

turning directions. 

c) A basic rule of gears is: “If a __________ gear (gear ‘A’) turns a 

__________ gear (gear ‘B’) the speed __________. On the other hand if 

a __________ gear turns a __________ gear the opposite happens and 

the speed __________”. 

d) It would be difficult to draw gears if you had to draw all the teeth, for this 

reason a gear can be represented by drawing _____ __________ 

overlapping where teeth __________ (as the picture above shown). 

ACTIVITY 8: What do the following pictures represent? 

ACTIVITY 9: We can work the gear ratio (velocity ratio) out using speed of 

rotation or number of teeth. If a gear system is made with a driver gear A that 

has 30 teeth and a driven gear B that has 20 teeth: 

Cams and followers 

when gear ‘A’ completes one revolution gear ‘B’ 

turns _____ revolutions ( _________ times). 

ACTIVITY 10: Complete the following sentences with the website information: 

a) A cam has two parts, the _______________ and the cam 

_______________. 

b) In a linear cam (also called _______________ _______________ cam), 

the follower moves _____ and _____, matching the _______________ of 

the profile. 



54

c) An _______________ cam is a disc with its centre of rotation positioned 

‘_____ centre’. 

d) A _______________ _______________ cam is a disc that rotates around 

a _______________. The disc is set at an __________. 

e) A _______________ cam is used where the fall of the follower must be 

_______________. Other profiles allow for a _______________ rise and 

fall of the _______________. 

ACTIVITY 11: Write the Spanish and English names of these followers: 



55

ACTIVITY 12: Complete the table below with the names of the cams or cam 

profiles: 

Ca 

m 

na 

me 

s 

En 

gli 

sh 

(tw 

o 

na 

me 

s): 

Sp 

ani 

sh: 

En 

gli 

sh 

(tw 

o 

na 

me 

s): 

Sp 

ani 

sh: 

En 

gli 

sh 

(tw 

o 

na 

me 

s): 

Sp 

ani 

sh: 

En 

Ca 

m 

pic 

tur 

es 



56

gli 

sh: 

Sp 

ani 

sh: 

En 

gli 

sh: 

Sp 

ani 

sh: 

En 

gli 

sh: 

Sp 

ani 

sh: 



57

Other mechanisms 

ACTIVITY 13: Complete the following exercise writing: the mechanism name, 

the names of the elements in each mechanism (arrows) and the sentence with 

the mechanism explanation. 

Mechanism 

name: 

Spanish 

name: 

Wh 

en 

the 

__ 

__ 

__ 

__ 

__ 

wh 

eel 

tur 

ns 

the 

__ 

__ 

__ 

__ 

__ 

fall 

s 

int 

o 

the 

‘di 

p’ 

bet 

we 

en 

the 

__ 

__ 

__ 

__ 

__, 



__________ perform 

different actions. Some 

restrict __________, some 

restrict __________ and 

others restrict __________. 

58

Me 

ch 

ani 

sm 

na 

me 

: 

Sp 

ani 

sh 

na 

me 

: 

so 

the 

__ 

__ 

__ 

__ 

__ 

wh 

eel 

ca 

n 

onl 

y 

tur 

n 

in 

on 

e 

__ 

__ 

__ 

__ 

__. 

Thi 

s 

me 

ch 

ani 

sm 

co 

nv 

ert 

s 

rot 

ary 



59

Me 

ch 

ani 

sm 

na 

me 

: 

mo 

tio 

n 

int 

o 

__ 

__ 

__ 

__ 

__ 

mo 

tio 

n, 

as 

the 

__ 

__ 

__ 

__ 

__ 

rot 

ate 

s 

the 

__ 

__ 

__ 

__ 

__ 

mo 

ve 

s 

for 

wa 

rds 

an 

d 

ba 

ck 

wa 

rds 

. 



60

Sp 

ani 

sh 

na 

me 

: 

Me 

ch 

ani 

sm 

na 

me 

: 

Sp 

ani 

sh 

na 

Wh 

en 

a 

sh 

aft 

ha 

s 

__ 

__ 

_ 

or 

mo 

re 

__ 

__ 

__ 

__ 

__ 

it 

ca 

n 

be 

cal 

led 

__ 

__ 

__ 

__ 

__ 

sh 

aft. 



61

me 

: 

Mechanism name: 

Spanish name: 

This 

arrangement 

of _____ is 

called a 

_____ and 

__________. 

The _____ is 

like a 

_____thread. 

The 

__________ 

is like a 

normal 

_____ gear. 

The _____ 

always 

drives the 

__________ 

round; it is 

never the 

opposite way 

round as the 

system tends 

to _____ and 

_____. 

Me 

ch 

ani 

sm 

na 



In this drilling machine, as 

the __________ is turned 

the table moves up and 

down the central pillar of 

the drill. The _____ and 

_____ reduces the _____ 

needed to move the table. 

62

me 

: 

Sp 

ani 

sh 

na 

me 

: 

ACTIVITY 14: What are the sprockets? 



63

e) FICHAS SOBRE EL PROYECTO DE TALLER 

HYDRAULIC HAMMER 

We are going to build a model of a hydraulic hammer. It will have two main parts 

or modules. Each module will contain a shaft, with a stand (vertical piece) and 

two squares (triangles), in order to hold the main pieces. 

(a) Cam wheel module: It will have the cams wheel and a crank. Once we try the 

model and check that it works in the right way, we will swap the crank for a 

waterwheel. We could add the waterwheel in the crank shaft, without taking 

the crank away, as well. 

(b) Hammer module: It will have a 

wooden piece, shaped as a hammer. 

Once we finish both modules, we need to put 

paddle 

them together, placing the hammer in the right position. 

The hammer will beat the anvil when each wheel’s cam 

makes the hammer rise. 



waterwheel 

64

f) FOTOCOPIA DE EXAMEN 

- Versión en inglés: 

MECHANISM - EXAM 

Name: 

Date: Group: 

EXERCISE 1: In the following picture of a compound lever, write the type of each 

lever and figure out the effort forces. 

(3 marks out of 10) 

EXERCISE 2: According to the pictures below, answer the following questions for 

each mechanism: 

(e) How many pulleys has the mechanism got? How many pulleys are fixed 

pulleys? How many pulleys are movable pulleys? 

(f) What effort force does a man need to lift a 180kg stone 3m up? 

(g) In pictures 1 and 2, what length of rope does he need to pull in? 


Picture 1 Picture 2 Picture 3 



65

EXERCISE 3: With the following compound mechanism: 

c) Write the name of each mechanism. 

d) Figure out the speed of rotation of each shaft if we connect a motor, 

revolving at 100rpm, to shaft I. 


EJERCICIO 4: 

a) Completa la siguiente tabla: 

Bibujo Nombre en inglés Nombre en español 

b) La figura siguiente muestra un mecanismo de __________ y __________. 

En estos mecanismos: 

- A __________ diámetro, mayor __________ de rotación. 

- Ambas __________ giran en la misma __________, a menos que la 

__________ esté cruzada. 

(1 punto extra) 



66

- Versión en español 

MECANISMOS - EXAMEN 

Nombre: 

Fecha: Grupo: 

EJERCICIO 1: En la siguiente figura de una palanca compuesta, escribe el tipo 

de cada palanca y calcula las potencias. 

(3 puntos sobre 10) 

EJERCICIO 2: De acuerdo con las siguientes figures, responde para cada 

mecanismo: 

(h) ¿Cuántas poleas tiene el mecanismo? ¿Cuántas poleas fijas tiene? 

¿Cuántas poleas móviles tiene? 

(i) ¿Qué fuerza ha de realizar un hombre para subir una piedra de 180kg 

una altura de 3m? 

(j) En las figures 1 y 2, ¿cuánta cuerda ha de recoger dicho hombre? 


Figura 1 Figura 2 Figura 3 



67

EJERCICIO 3: En el siguiente tren de mecanismos: 

e) Escribe el nombre de cada mecanismo del tren. 

f) Calcula la velocidad de rotación de cada eje si conectamos un motor, 

girando a 100rpm, al eje I. 


EXERCISE 4: 

c) Complete the table: 

Pic En Sp 

tur gli ani 

e sh sh 

na na 

me me 

d) The following picture shows a __________ and __________ mechanism. In 

these mechanisms: 

- The __________ the diameter, the higher the __________ of rotation. 

- Both __________ turn in the same __________, unless the __________ 

is crossed. 

(1 extra-mark) 



68

FUENTES 

Además de las dos páginas Web que se mencionan, con las que se 

trabajan las actividades del aula de informática: 

● http://flying-pig.co.uk/mechanism/index.html 

● http://www.technologystudent.com/index.htm 

Se han empleado dos imágenes obtenidas de las siguientes páginas: 

● Fotografía de Arquímedes: 

http://www.educomputacion.cl/images/stories/arquimedes.jpg 

● Watch escapement: 

http://www.bhi.co.uk/hints/images/lever1.gif 



69

- 

HY 

PO 

TH 

ES 

IS 

-If 

the 

len 

gth 

of 

the 

rop 

e 

is 

too 

sh 

ort 

… 

… 

… 

…. 

. 

- 

Wh 

at 

will 

ha 

pp 

en 

if 

g) IN THE ENGLISH LESSON 

COMPLEX 

DESCRIPTIONS 

-A pneumatic 

hammer is a tool 

WHICH works 

by means of 

compressed air 

-A fixed pulley is 

a mechanism 

WHOSE axle is 

fixed. 

KEY FUNCTIONS-HOW TO MAKE… 



70

the 

loa 

d 

… 

… 

… 

… 

… 

ACTIVITY 1: WARM UP-DISCUSS 

-WHAT ARE THE FOLLOWING MECHANISMS CALLED? 

-WHAT ARE THEY USED FOR? 

pulley crank belt and pulley gear cam lever 



71

ACTIVITY 2: CHECK THE FOLLOWING DESCRIPTIONS. 

2a-NOTICE THE STRUCTURE OF COMPLEX DESCRIPTIONS. 

a-Any device that is used for transporting people or things is called a vehicle. 

b-An elevator is a platform that is raised and lowered to transport people or 

weight. 

c-A pneumatic drill is a tool which is powered by compressed air. 

d-A truck whose content can be emptied without handling is called a dump truck. 

2b-NOW COMPLETE THE FOLLOWING DESCRIPTIONS 

a-Mechanims are elements that……………. 

b-Any object that transforms or transmits energy is called………….. 

c- A toothed wheel is called a…………….. 

d-A gear driven by a chain is called………………. 

c-A lever is a rigid bar that…………… 

d-A pully is a wheel with a groove that………….. 

e-A winch is a drum or spool whose………………….. 

ACTIVITY THREE: WATCH THE FOLLOWING VIDEOS AND ANSWER THE 

QUESTIONS. 

3.1http://www.youtube.com/watch?v=17qjUcR7-fI: HOW PULLEYS WORK 

- -What can pulleys be used for? 

-How many types of pulleys are mentioned? What are the differences 

between them? 

3.2http://www.youtube.com/watch?v=5QCvONWi4mk&feature=PlayList&p=E3F4D50 

F9ADA54E9&index=0&playnext=1: HOW GEARS WORK. 

-What’s the purpose of a spur gear? 

-What kinds of combinations of gears appear on the video? How do they 

work? 

3.3http://www.youtube.com/watch?v=PW7ztbwJKBk: HOW LEVERS WORK 

-Identify the three types of lever’s arrangements that are explained. 

-What objects use each kind of lever arrangement? 



72

ACTIVITY FOUR: GROUP PROJECT WORK 

Do you know the name of the man in the picture? 

He was born in 1452. You will be surprised to find out that he invented several 

machines using all the mechanisms we have studied. Visit the following website 

(The Institute and Museum of the History of Science), and write a brief summary 

of his work. 

http://brunelleschi.imss.fi.it/genscheda.asp?appl=LIR&xsl=slideshow&lingua=EN 

G&chiave=101000 

Include the following information: 

-Short biography 

-Machines he designed 

-Mechanisms he used 

-Successful/unsuccessful results. 



73

“MECHANISMS” - educastur.princast

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