To which of the following lifting machine the above figure belongs to?

Explanation:

Differential pulley block

This uses an endless chain or rope wound over an upper pulley block, consisting of two pulleys of differing diameters, and a lower pulley block carrying the load with a loop, where the effect is applied.

Additional Information

Simple wheel axle

The wheel and axle is a type of simple machine made of a wheel fixed to an axle (smaller) so that these two components revolve in conjunction in which a force is transmitted from one part to the other. Lifting or displacing weight was probably the earliest use of the wheel and axle in human history.

Simple pulley

A pulley is a simple machine made with the help of a grooved wheel and a rope, a wire, or a chain. In a pulley mechanism, the load is attached to one end of the rope, and the force is applied to the other end. The applied force is responsible for either lifting or lowering the load.

Worm-geared pulley block

It consists of a square threaded screw S (known as a worm) and a toothed wheel (known as worm wheel) geared with each other. Wheel A is attached to the worm, over which passes a rope. Sometimes, a handle is also fixed to the worm (instead of the wheel). A load drum is securely mounted on the worm wheel.