JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B. Tech II Year MINE MECHANIZATION I Previous Question Paper (September/October - 2023 - R18)
Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
Part A
Compare compressed air and hydraulic powers.
Answer
- Compressed Air: Uses air as the working medium; it is safe in gassy mines, provides simple control, and is flexible, but has low efficiency (10-15%) and high transmission losses.
- Hydraulic Power: Uses pressurized oil; it offers high power density, precise control, and high efficiency (80-90%), but presents fire hazards and requires leak-proof systems.
Explain hydraulic coupling and its use in mining.
Answer
A hydraulic coupling (or fluid coupling) is a hydrodynamic device used to transmit rotating mechanical power. It consists of an impeller (pump) and a runner (turbine) inside a housing filled with oil. As the impeller rotates, it accelerates the oil, which strikes the runner, causing it to rotate. In mining, it is used in conveyor drives and haulage systems to provide a smooth start, protect the motor from overload, and dampen torsional vibrations.
Why steel wire ropes are recapped during their life and at what frequency?
Answer
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List the types of signaling in Rope haulage.
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Define the term “Track extension”.
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Define the terms “Track rope and Traction Rope”.
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What are the demerits of using a locomotive in a coal mine?
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List the application of Stage loader in long wall mining.
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How air compressors are classified?
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What are differences between Air motors and Air compressors?
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Part B
Explain with sketches a disc clutch and an Oldham coupling and explain their principle of operations.
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Discuss the gear terminology with the help of suitable sketch. Discuss the importance of gear drives. Give a brief classification of gear.
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What are the advantages of flat belt drives? Explain the various types of flat belt drives. Give a brief description of belt materials.
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A gear box is to be arranged for four speeds in approximate geometrical progression, one of which is to be a direct drive. The driving shaft transmits 30 kW at 2400 rev./min, the speed of lay shaft is approximately 400 rev/min. The distance between the axes and the driving shaft and the lay shaft is 180mm and all teeth are of module 6. Find the necessary numbers of teeth in each pair of gears.
Answer
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Explain exhaust conditioner and flame trap fitted to diesel locomotive.
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Explain with neat diagrams the principle and operation of direct and endless rope haulages, with their merits, demerits and fields of application.
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A 5000 kg Locomotive runs at a Speed of 3 m/s along a Level track. The Coefficient of adhesion at the track is 0.23, and the rolling resistance of the Locomotive is 100 N per 1000Kg. Determine the maximum power available for hauling the train in kW.
Answer
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Describe with sketches different types of safety devices on the tracks of i) Direct Rope Haulage ii) Endless Rope Haulage?
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Explain the terms “ Crossing and turn tables” in haulage tracks.
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Describe the construction and working of Mono-cable aerial ropeway.
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Discuss on Haulage Track joints and Banking of track laying.
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Describe the Bi cable aerial ropeway system with sketch.
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What do you understand by a Draw Bar Pull Capacity of a locomotive engine?
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A 12 tonne dissel locomotive of 60 k W is playing in an underground haulage road way. The coefficient of adhesion is 0.25 and the maximum gear efficiency is 80%. Calculate the speed in m/s at which it will haul a train at its full power?
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Explain different types of locomotive haulage system with advantages and disadvantages with neat sketch.
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An open belt running over two pulley 240 mm and 600 mm diameter connects two parallel shafts 3m apart and transmits 4 k W from the smaller pulley that rotates at 300 rpm co- efficient of friction between the belt and pulley is 0.3 and the safe working tension is 10N per mm width. Determine i) minimum width of the belt ii) length of belt required.
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Describe operation, maintenance of screw type compressor.
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Describe with a neat sketch the construction and working of a single stage single acting reciprocating air compressor.
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Explain tools powered by air compressors.
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Describe operation, maintenance of axial flow type compressor.
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