Simple Mechanisms - 1 - GATE ME Free MCQ Test with solutions

Structure and machine both are permanent construction. e.g. structure: Roof truss, machine frame, railway bridge etc.

If two mating links have a turning as well as sliding motion between them, they form a screw pair. This is achieved by cutting matching threads on the two links. The lead screw and the nut of a lathe is a screw pair.

The mechanisms used to overcome a large resistance of a member with a small driving force are known as snap action or toggle mechanisms.

The mechanisms used to overcome a large resistance of a member with a small driving force are known as snap action or toggle mechanisms. They find their use in a variety of machines such as stone crushers, embossing presses, switches etc.

The inversions of a double slider crank mechanism include:

• Oldham coupling: Used for connecting two shafts that are slightly misaligned.
• Elliptic trammel mechanism: Generates an elliptical path by sliding along two perpendicular axes.

Except scotch yoke, all three are inversion of single slider chain.

Firstly, this topic is discussed under KINEMATICS PAIRING.

Based on nature of contact between elements;

Lower Pair: The joint by which two members are connected has surface contact (one element slides with another’s surface).
Discussion:
surface contact means large area of contact between two surfaces which divided into two categories:
i) Planar (2D) Mechanism -(2 axis movements)
ii) Spatial (3D) Mechanism -(3 axis movements)
Example:
Sliding pairs, turning pairs, screw pairs.

Higher Pair: The contact between pairing elements takes place at a point or a line.
Discussion:
it’s mentioned ‘a point’ or a ‘line’ because the surface contact between pairing elements is very small until it is considered as a point-to-point contact.
Example:

the contacts is relatively very small between pairing elements.

Binary joints :I and F
Ternary joints : H, G, E, C, A and D
Quaternary joint : B