mechanisms

1. rotary-linear transformation
   1. wheel
      1. reduce contact with the ground
      2. decrease friction
      3. moves forward a distance that is equals to its circunference.
      4. less force to move vehicles with larger wheels
         1. they move quickly
   2. rack & pinion
      1. 2 parts
         1. rack
            1. bar with many teeths
               1. are interlock
         2. pinion
            1. gear with teehts
      2. sliding doors
      3. conveyor belts
   3. nut & bolt
      1. 2 parts
         1. bolt
            1. spiral groove
         2. nut
            1. turns around it
      2. move forward
      3. lift loads
         1. reducing system
      4. hold things together
   4. winch & crank
      1. cylinder that rotates around a horizontal axis
      2. increases the force

         Annotations:

         • the crank
      3. transform rotary to linear

         Annotations:

         • the winch
      4. like Law of the Lever

         Annotations:

         • F x d = R x r
      5. lift or pull heavy loads
2. reciprocating rotary-linear transformation
   1. crank & rod
      1. piston

         Annotations:

         • moves foward and backward
      2. rod

         Annotations:

         • turns the first wheel
         1. second wheel

            Annotations:

            • turns because it is connected to the first wheel by another rod
      3. windscreen wisper
   2. crankshaft
      1. multiple rods to one shaft

         Annotations:

         • rods are connected to cranks, and cranks are connected to the crankshaft
      2. syncronise the movements of various parts
      3. combustion motors that use pistons
   3. cam
      1. irregular shaped device that rotates on a shaft
      2. follower
         1. move other parts or turns a switch & off
      3. camshaft

         Annotations:

         • multiple cams on one shaft. 
         •  It is use to syncronise the movements of various parts.
         1. toys
      4. eccentric cams

         Annotations:

         • circular cams with an axis of rotation that is off-centre.
         • because they rotate in an irregular or eccentric way
         1. sewing machines

1. speed reduction
   1. brakes

      Annotations:

      • use friction to reduce speed they are activated by some type of lever.
      1. disc brakes

         Annotations:

         • a disc connected to an axle
         • brake apply pressure to the disc
      2. band brakes

         Annotations:

         • a drum connected to an axle.
         • a flexible band applies pressure to the outside of the drum 
         • these brakes were used in carriages and they depended on the strength of the driver
      3. drum brakes

         Annotations:

         • a drum is connected to the axle.
         • a pair of brake shoes apply pressure to the inside of the drum
2. direction control
   1. rachets

      Annotations:

      • mechanism that controls the direction of motion. 
      1. it allows motion in one direction.

         Annotations:

         • but not in the other.
      2. rachets in watches

1. accumulation
   1. springs

      Annotations:

      • flexible devices that absorb energy when we apply force to them. we can release the energy in acontrolled way
      1. compression
         1. sofas
      2. traction
         1. metallic bed frames
      3. torsion
         1. clothes pins
2. dissipation
   1. suspension systems

      Annotations:

      • they are use to absorb and dissipate motion
      1. shock absorbers
         1. spiral steel springs
      2. leaf springs
         1. long, curved pieces of steel of differents lengths placed on top of each other and joined in the middle

Annotations:

• they are use to transmit rotation from one axis to another

1. rigid couplings

   Annotations:

   • form a permanent connection between two shafts. these shafts may have different diameters, but they must be perfectly aligned.
2. clutches

   Annotations:

   • form a rigid connection which isn't permanent.
   • this systemm also permits various combinations that chgange the gear ratio between the engine and the wheels.
3. flexible couplings

   Annotations:

   • they are also useful

1. plain

   Annotations:

   • formed by two rings
   • one of the ring is connected to the rotating shaft 
   • the other is connected to the support.
   • plain bearings are made of smooth materials, but they need lubrication to reduce friction
   • plain bearings are quiet, but they produce a lot of heat at the high speeds
2. antifriction

   Annotations:

   • they are used in many machines
   • they reduce the amount of surface contact between the shaft and other parts.
   1. the inner ring

      Annotations:

      • is in contact with the rotating shaft
   2. the outer ring

      Annotations:

      • is connected to the rest of the mechanism
   3. the rolling elements

      Annotations:

      • are cylindrical rollers or round balls ( ball bearings).
   4. the retainer

      Annotations:

      • keeps the rolling elements in position.

Annotations:

• transmits motion in one direction, and turns freely in the opposite direction.

1. mechanism on our bycicles