Differentiate between machine and mechanism.

Short Answer:

A machine is a device that converts energy into useful work and helps to perform tasks by transmitting or modifying force and motion. It performs real work using energy.
A mechanism, on the other hand, is a part of a machine that controls or transmits motion between different parts. It does not perform work but helps in transforming the type or direction of motion. In short, every machine contains one or more mechanisms, but a mechanism alone is not a complete machine.

Detailed Explanation :

Difference between Machine and Mechanism

In mechanical engineering, both machine and mechanism are closely related terms, but they have different meanings and purposes. A machine performs useful work by converting energy from one form to another, while a mechanism helps in transmitting and transforming motion within the machine. Understanding the difference between these two concepts is very important because every machine is built using one or more mechanisms.

Machine

A machine is a device that receives energy in some form and transforms it into useful work to perform a desired operation. It helps to reduce human effort, save time, and increase accuracy and efficiency. Machines are designed to transmit motion, change the direction of force, or multiply speed or force.

For example, a lathe machine converts electrical energy into mechanical motion to rotate a workpiece and perform operations like cutting, shaping, or drilling. Similarly, a car engine converts chemical energy of fuel into mechanical energy to drive the vehicle.

A machine performs actual work because it converts energy into mechanical output. It is a complete system made up of several mechanisms working together.

Mechanism

A mechanism is a part or portion of a machine that transmits motion from one point to another. It is mainly concerned with how motion is generated, controlled, and transformed, but it does not perform any useful work by itself.

For example, the crank and slider arrangement in an engine is a mechanism that converts the reciprocating motion of the piston into rotary motion of the crankshaft. On its own, it cannot produce power or perform work unless it is connected to other parts forming a complete machine.

Thus, a mechanism is the internal motion-transmitting system, while the machine is the complete working unit that performs useful tasks.

Main Points of Difference

  1. Purpose:
    • The machine performs actual work using energy.
    • The mechanism only transmits or changes the type of motion.
  2. Function:
    • A machine converts energy into useful work.
    • A mechanism converts input motion into desired output motion.
  3. Energy Transmission:
    • In a machine, energy passes through the system to produce output.
    • In a mechanism, no energy is transferred; only motion is transmitted.
  4. Examples:
    • Machine: Engine, Lathe machine, Electric fan, Pump.
    • Mechanism: Crank and slider, Cam and follower, Gear train.
  5. Completeness:
    • A machine is a complete working device.
    • A mechanism is a part of the machine that cannot work independently.
  6. Objective:
    • The main aim of a machine is to perform useful work.
    • The main aim of a mechanism is to transmit motion efficiently.
  7. Output:
    • The machine gives a measurable output in the form of work or power.
    • The mechanism gives output in the form of motion or movement.

Examples Explaining the Difference

Example 1 – Internal Combustion Engine:
In an engine, the machine as a whole produces power by burning fuel. The crank and connecting rod mechanism inside it converts the reciprocating motion of the piston into rotary motion of the crankshaft. Thus, the engine is the machine, and the crank and connecting rod is the mechanism.

Example 2 – Electric Fan:
The electric fan as a machine converts electrical energy into mechanical energy to rotate its blades. The mechanism inside, which consists of the rotor and shaft, transmits motion from the motor to the blades.

Example 3 – Sewing Machine:
The sewing machine performs the useful work of stitching. Inside it, a mechanism of levers and gears converts rotary motion of the motor into up-and-down motion of the needle.

These examples make it clear that a mechanism is always a part of a machine that helps it function properly.

Relation between Machine and Mechanism

Every machine is made up of one or more mechanisms. Mechanisms are combined in a proper way to form a machine that can perform useful work. For example, the mechanisms inside an automobile engine, gearbox, and transmission system work together to make the vehicle move. Hence, a mechanism is the foundation or skeleton, and the machine is the complete working system.

Conclusion

In conclusion, the main difference between a machine and a mechanism is that a machine performs actual work by converting energy into useful output, while a mechanism only transmits or changes motion within the machine. A mechanism is an essential part of every machine but cannot work alone. Both are fundamental concepts of mechanical engineering, as understanding them helps in designing efficient machines and motion systems used in industries and daily life.