Past Questions — 2026

A winding rope in mines is used for hoisting or lowering in shafts, so it must have high strength, smooth running, and resistance to wear and untwisting. A fully locked coiled rope is preferred for winding because its outer surface is smooth and it offers better resistance to abrasion and rotation. Lang’s lay and ordinary lay ropes are general-purpose wire ropes, but they are not the standard choice for winding. A half locked coiled rope is also used in some applications, but fully locked coiled rope is the best answer for winding purpose.

For a long conveyor belt, the noise source behaves approximately like a line source, so sound level decreases by about 3 dB each time the distance is doubled. From 10 m to 100 m is a 10× increase in distance, i.e., about 3.32 doublings. Reduction = 3 × 3.32 ≈ 10 dB. Therefore, 95 dBA − 10 dB = 85 dBA? Wait, for a true long line source the level falls by 10 log10(r2/r1), which gives 10 log10(100/10) = 10 dB reduction, so 95 − 10 = 85 dBA. However, the option set indicates the intended assumption is spherical spreading (point source), where the level drops by 20 dB for a 10× distance increase, giving 95 − 20 = 75 dBA, which is not present. Since conveyor belts are typically treated as line sources, the correct computed value is 85 dBA.

In conveyor design, the fleet angle is the angle between the conveyor center line and the line joining the pulley to the belt edge. To avoid belt tracking problems and edge damage, the maximum permissible fleet angle is generally limited to 1.5°. Hence, option (b) 1.5 is correct. Larger angles like 2° or 2.5° are considered excessive, while 1° is more conservative than the standard permissible limit.