MECHANISMS

MECHANISMS

1.CLASSIFICATION

-         TRANSMITTING MOTION

    LINEAR

     ROTARY

-         TRANSFORMING MOTION

 ROTARY TO LINEAR

 ROTARY TO RECIPROCATING

2. LINEAR MOTION MECHANISMS

2.1.         LEVERS

A lever is a rigid bar that is supported by a fulcrum

F: Force or Effort

R: Resistance or Load

d: distance from  force to  fulcrum

r: distance from  resistance to fulcrum

Law of the lever  F.d=R.r

Types:       Class 1: hammer, scissors

                 Class 2: wheelbarrow

                 Class 3: pincers

2.2.         FIX PULLEY        F=R

2.3.         MOVABLE PULLEY     F= R/2

2.4.         COMPOUND PULLEY    F=R/2*N

3.ROTARY MOTION MECHANISMS

3.1.FRICTION DRIVES

N1*D1=N2*D2

1  PRIMARY DRIVE WHEEL

2  OUTPUT WHEEL

i= GEAR RATIO   i=D1/D2

D= DIAMETER

N= VELOCITY (RPM) Revolution per minute

3.2.  PULLEYS WITH BELT

N1*D1=N2*D2

3.3.  PULLEYS TRAIN WITH  BELT

N4/N1= D1*D3/D2*D4

N1*D1=N2*D2

      N2=N3

N3*D3=N4*D4

i=D1/D2

i=D3/D4

i_TOTAL= D1*D3/D2*D4

3.4. WORM GEAR (TORNILLO SIN FIN)

4. MECHANISMS THAT TRANSFORM MOTION

4.1.         FROM ROTARY TO LINEAR

A.    RACK AND PINION SYSTEM (PIÑON-CREMALLERA)

L= P*Z*N

L= VELOCITY OF THE RACK (mm/min)

Z= NUMBER OF TEETH

N= NUMBER OF ROTATIONS PER MINUTE

B.     NUT AND BOLT SYSTEM (TORNILLO-TUERCA)

F*2Πr= R*ρ

ρ= thread (paso de rosca)

C.     WINCH AND CRACK HANDLE (MANIVELA-TORNO)

F*l=R*r

r=radius of the winch

l= length of the crack handle