MECHANISMS

MECHANISMS

1. TRANSFORMATION OF MOTION

   • Rotary-linear transformation
     • Wheel
       • They help us to move easily because they reduce our contact with the ground and recrease friction. Vehicles with larger wheels requires less force to move and they move more quickly
     • Rack and pinion mechanism
       • It has two parts: A rack (Bar with many teeth) and a pinion (A gear that interlocks with the rack. We use rack and pinion for devices that require precise movements.
     • Nut and bolt mechanism
       • It transforms rotary motion into linear motion It has two parts: A nut that turns around the bolt (A shaft with a spiral groove.
     • Wrinch and crak mechanism
       • A cilinder that rotates around a horizontal axis.
   • Reciprocating rotary-lonear transformation
     • Crack and rod mechanism
       • A piston moves a rod forward and backward. This rod turns the first wheel. The second wheel turns because its connected to the first wheel by another rod.
     • Crankshaft mechanism
       • Multiple rods connected to one shaft.
     • Cam mechanisms
       • A cam is a device that rotateson a shaft. When the cam rotates it pushes a bar called follower. Follower can move other parts.

2. MECHANISMS THAT CONTROL MOTION

   • Speed reduction: Brakes
     • Brakes uses friction to reduce speed. They are activated by levers. There are 3 types: Disc brakes: A disc connected to a axle Band brakes: A band connected to an axle Drum brakes: A drum connected to an axle
   • Direction control: Ratchets
     • Ratchet is a mechanism that controls the direction of motion. It just allows motion in one direction.

3. ENERGY ACCUMULATION MECHANISM

   • Accumulation: Springs
     • Strings are flexible devices that absorb energy when we apply force to them We push on compression spings We pull on traction springs We bend torsion springs
   • Dissipation: Suspension systems
     • This mechanisms absorbs and disiates motion making driving more comfortable

4. COUPLING AND CLUTCHES

   • It transmits rotation from one axis of rotation to another. There are various coupling mechanisms:  Rigid couplings: Permanent connection between two shafts  Clutches: They form a rigid connection that is not permanent Flexible couplings: They are also useful

5. BEARINGS

   • Plain bearings
     • Formed by two rings. One of them is connected to therotating shaft and the other is connected to a support.
   • Antifriction bearings
     • They reduce the amount of surface contact between the shaft and other parts
     • Inner ring
       • A part of an antifriction bearing mechanism that is in contact with the rotating shaft
     • Outer ring
       • Another part of the mechanism that is connected to all the mechanism 
     • Rolling elements
       • They are cilindrical rollers or round balls
     • Retainer
       • It keeps the rolling elements in position

6. FREEWHEEL

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