JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II MINE MECHANISATION-I Previous Question Paper (July/August - 2021 - R16)

An epicyclic gear train, also known as a planetary gear train, consists of one or more planet gears revolving around a central sun gear. The system typically includes a sun gear, a carrier (arm) that holds the planet gears, and an outer ring gear (annulus) with internal teeth. Unlike simple gear trains, the axes of the gears in an epicyclic train are not fixed in space but move relative to each other.

Key features include:

• Compactness: It provides high gear ratios in a small volume, making it ideal for mining machinery and heavy-duty transmissions.
• Coaxial alignment: The input and output shafts are aligned on the same axis.
• Versatility: By holding one component stationary (sun, planet carrier, or ring), different velocity ratios and directions of rotation can be achieved.

Given: Diameter (d) = 0.72 m, Speed (N) = 360 rpm, Power (P) = 15 kW = 15000 W, T1 = 3T2, Maximum tension (T1) = 16 N/mm width (w). First, calculate the belt velocity (v):

Power transmitted is given by:

Since T1 = 3T2, then T1 - T2 = 3T2 - T2 = 2T2. Also, T2 = T1 / 3. Substituting into the power equation:

Given the maximum allowable tension is 16 N per mm of width, the required width (w) is:

Therefore, a belt width of approximately 104 mm is necessary.