JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III MINE MECHANIZATION - II Previous Question Paper (August - 2022 - R16)

A drum winder consists of a cylindrical drum around which the winding rope is coiled. In a single-drum winder, one rope is used for one cage, while a double-drum winder allows for balanced winding where one cage ascends as the other descends. The drum may be plain or grooved to guide the rope. During the winding cycle, the rope layers build up on the drum, which changes the effective diameter and torque requirements. It is primarily used for shafts of moderate depth where the rope can be stored on the drum.

A friction winder (or Koepe winder) uses a friction pulley (sheave) instead of a drum. The rope passes over the pulley, and the drive is transmitted through the friction between the rope and the pulley lining. The system is inherently balanced, as the two cages or skips are suspended from the ends of the same rope. A tail rope (balance rope) is usually attached beneath the conveyances to compensate for the weight of the winding rope. This design is highly efficient for deep shafts because the rotating mass is significantly lower than that of a drum winder, and it allows for multi-rope installations to handle heavy loads.

Key differences include:

• Drum winders store the entire length of the rope on the drum, whereas friction winders do not store rope.
• Friction winders are more suitable for deep shafts due to lower inertia and the use of tail ropes.
• Drum winders are better suited for multi-level winding, as they can easily adjust the rope length for different landing levels.

Sketch description: A drum winder sketch would show a large cylindrical drum mounted on a shaft, with ropes winding in layers. A friction winder sketch would show a central friction pulley with a single rope passing over the top, connecting two conveyances (cages) on either side, with a tail rope looping at the bottom of the shaft to connect the two conveyances.

The headgear, also known as a headframe or gallows frame, is a structural tower located directly above the mine shaft. It supports the headgear pulleys (sheave wheels) at its summit, which guide the hoisting ropes from the winding engine to the shaft compartments. The structure is typically constructed of steel lattice or reinforced concrete to withstand the heavy dynamic loads of the winding system.

The headgear pulley is a large diameter wheel mounted at the top of the headgear. Its primary function is to change the direction of the winding rope from the horizontal or inclined plane of the winding engine to the vertical orientation required for the shaft. It also acts as a support for the cage or skip, ensuring the rope remains aligned within the shaft guides.

Key functions of the headgear and pulley assembly include:

• Supporting the weight of the winding ropes, cages, skips, and the payload being hoisted.
• Providing a stable platform for the headgear pulleys to rotate, allowing for smooth rope transition.
• Facilitating the attachment of safety detaching hooks or catch-gear to prevent over-winding accidents.
• Housing the shaft collar area, providing a secure interface for loading and unloading personnel and minerals.
• Maintaining the necessary fleet angle for the winding ropes to prevent excessive wear and ensure proper coiling on the drum.

In a typical arrangement, the headgear is designed to be rigid enough to resist the tension exerted by the winding ropes and the lateral forces caused by wind or mechanical operation. The diameter of the headgear pulley is strictly regulated based on the diameter of the winding rope to minimize fatigue and bending stresses, typically maintained at a ratio of at least 80:1 to 100:1 relative to the rope diameter.