# Comparison among Machine, Mechanism and Structure

In this article, on the first table, I have compared the differences between the mechanism and machine. On the second table, I have compared the differences between the structure and machine.

The difference between Mechanism and Machine are listed below in tabular form.

S.no
Mechanism
Machine
1 Mechanism transmits and modifies the motion. Machine changes the mechanical work.
2 A mechanism is an outline of the machine to produce define motion between various links or joints  Fig. 1). Machine will have many mechanisms for transmitting the mechanical work or power.
3 Where kinematic chain is analyzed as a mechanism, no special consideration need to be given to the formed cross-section of the links. In a machine, cross-section and proportions are to be considered to give stiffness, strength, and clearance to the paths of the machine.
4 Examples of mechanisms are clocks, typewriter, steering mechanism in a car, etc. Examples of the machine are slotting, lathe, shaper in the workshop, (Shaper receives mechanical power which is suitably converted to do the work of cutting the metal), etc.

The difference between a machine and structure are listed below in tabular form.

S.no
Structure
Machine
1 In structure, no relative motion exists between its members. In machine, relative motion exists between its parts.
2 Members meant for carrying loads are subjected to straining action. Machine links are meant to transmit motion and forces which are dynamic (both static and kinetic).
3 Structure serves to modify and transmit forces. Machine serves to modify and transmit mechanical work.
4 Examples of structures are roof trusses, bridges, building and machine frames. Examples of machines are a slotting, shaper, lathe, and screw jack.