L E S S O N 3 - 4 , A N I N T R O D U C T I O N T O M E C H A N I C A L T E C H N O L O G Y

ENGINEERING DESIGN

OBJECTIVES

• Explain how mechanical systems enhance human capabilities• Describe the factors that affect a mechanical

system’s efficiency• Analyze the functioning of the mechanical

systems in the designed world• Apply engineering design process to solve a

problem

MECHANICAL TECHNOLOGY

• The assembly of mechanical components to produce, control, and transmit motion.

COMMON COMPONENTS

• Levers• Inclined planes• Wedges• Wheels and axels• Pulleys• Screws• Gears• Cams• Linkages• Shafts

• Couplings• Cables• Bearings• Brakes• clutches

SIMPLE CONTROLS

• Complex systems may have layers of controls• Some controls operate particular parts of the

system, while others control other controls• Even the most fully automatic systems require

human control at some point.

PERFORMANCE EVALUATIONS

Mechanical AdvantageTo find the MA of a machine, you can divide the resistance force by the effort force. Most of the time the resistance force is the weight of the object in Newtons.

EfficiencyThe resultant amount of work (output), divided by the amount of work put into the machine (input)

SCIENTIFIC CONCEPTS

• Force: a push or pull exerted by one object on another• Motion: any physical movement or change in

position or place• Energy: the ability to do work. • Work: the transfer of energy from one physical

system to another, expressed as the product of a force and the distance through which it moves a body in the direction of the force • Work (foot-pounds or Newton-meters) = Force

(pounds or Newtons) x Distance (feet or meters)

SCIENTIFIC CONCEPTS (CONT)

• Power: Force divided by time. Measured in foot-pounds, newton-meters, or watts.• Gravity: the natural tendency of objects with

mass to attract each other.• Friction: a force that opposes the motion or

intended motion of a body in contact with another body.