JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II MECHANICAL TECHNOLOGY Previous Question Paper (April/May - 2018 - R15)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit.
Part A
Define Pressure angle and stroke of the follower.
Answer
The pressure angle is the angle between the direction of the follower motion and the normal to the pitch curve at any point. The stroke of the follower is the maximum distance or displacement of the follower from its lowest position to its highest position during one complete rotation of the cam.
Write short notes on cams and followers.
Answer
A cam is a rotating or reciprocating machine element that imparts a specific motion to another element, known as the follower, through direct contact. Cams are used to convert rotary motion into linear or oscillating motion. Followers are classified based on their surface shape (knife-edge, roller, flat-faced, or spherical) and their path of motion (radial or offset).
What is velocity ratio of the belt?
Answer
Sign in to view the complete answer paper.
What are different types of chains?
Answer
Sign in to view the complete answer paper.
What is Addendum and Pitch circle?
Answer
Sign in to view the complete answer paper.
What are simple and compound gear trains?
Answer
Sign in to view the complete answer paper.
What is an IC Engine?
Answer
Sign in to view the complete answer paper.
What is compression ratio?
Answer
Sign in to view the complete answer paper.
What is clearance volume in a reciprocating air compressor?
Answer
Sign in to view the complete answer paper.
What is a rotary compressor?
Answer
Sign in to view the complete answer paper.
Part B
A cam rotating clockwise with a uniform speed is to give the roller follower of 20 mm diameter with the following motion: a) Follower to move outwards through a distance of 30 mm during 120° of cam rotation; b) Follower to dwell for 60° of cam rotation; c) Follower to return to its initial position during 90° of cam rotation; d) Follower to dwell for the remaining 90° of cam rotation. The minimum radius of the cam is 45 mm and the line of stroke of the follower is offset 15 mm from the axis of the cam and the displacement of the follower is to take place with simple harmonic motion on both the outward and return strokes. Draw the cam profile?
Answer
Sign in to view the complete answer paper.
Derive expressions for displacement, velocity and acceleration for a tangent cam operating on a radial-translating roller follower, when the contact is on straight flank.
Answer
Sign in to view the complete answer paper.
A cam profile consists of two circular arcs of radii 26 mm and 14 mm, joined by straight lines, giving the follower a lift of 14 mm. The follower is a roller of 24 mm radius and its line of action is a straight line passing through the cam shaft axis. When the cam shaft has a uniform speed of 700 rev/min, find the maximum velocity and acceleration of the follower while in contact with the straight flank of the cam?
Answer
Sign in to view the complete answer paper.
Obtain an expression for the length of a belt in a cross belt drive.
Answer
Sign in to view the complete answer paper.
A leather belt 125 mm wide and 6 mm thick transmits power from a pulley 750 mm diameter which runs at 500 r.p.m. The angle of lap is 150° and μ = 0.3. If the mass of 1 m^3 of leather is 1000 kg and the stress in the belt is not to exceed 2.75 MPa, find the maximum power that can be transmitted.
Answer
Sign in to view the complete answer paper.
What is centrifugal tension in a belt? How does it affect the power transmitted?
Answer
Sign in to view the complete answer paper.
An open belt 120 mm wide connects two pulleys mounted on parallel shafts with their centres 2.6 m apart. The diameter of the larger pulley is 470 mm and that of the smaller pulley 320 mm. The coefficient of friction between the belt and the pulley is 0.3 and the maximum stress in the belt is limited to 16 N/mm width. If the larger pulley rotates at 150 r.p.m., find the maximum power that can be transmitted.
Answer
Sign in to view the complete answer paper.
State and prove the law of gearing. Show that involute profile satisfies the conditions for correct gearing.
Answer
Sign in to view the complete answer paper.
A pinion having 20 involute teeth of module pitch 6 mm rotates at 200 r.p.m and transmits 1.5 kW to gear wheel having 50 teeth. The addendum on both the wheels is 1/4 of the circular pitch. The angle of obliquity is 20°. Find (i) the length of the path of approach;(ii) the length of the arc of approach;(iii) the normal force between the teeth at an instant where there is only pair of teeth in contact.
Answer
Sign in to view the complete answer paper.
Derive an expression for the length of the arc of contact in a pair of meshed spur gears.
Answer
Sign in to view the complete answer paper.
In an epicyclic gear train, the number of teeth on wheels A, B and C are 48, 24 and 50 respectively. If the arm rotates at 400 r.p.m., clockwise find: 1.Speed of wheel C when A is fixed and 2.Speed of wheel A when C is fixed.
Answer
Sign in to view the complete answer paper.
Draw the Diesel cycle on P-V and T-S diagrams mark the various processes and explain.
Answer
Sign in to view the complete answer paper.
What is meant by abnormal combustion? Explain the phenomena of knock in SI engines.
Answer
Sign in to view the complete answer paper.
Explain the difference between two stroke and four stroke engines.
Answer
Sign in to view the complete answer paper.
A four-stroke gas engine has a bore of 25 cm and stroke of 35 cm and runs at 400 rpm firing every cycle. If air-fuel ratio is 4:1 by volume and volumetric efficiency on NTP basis is 80%, determine the volume of gas used per minute. If the calorific value of the gas is 9 MJ/m^3 at NTP and the brake thermal efficiency is 28% determine the brake power of the engine?
Answer
Sign in to view the complete answer paper.
Explain with neat sketch two stage air compressors with inter cooling.
Answer
Sign in to view the complete answer paper.
Explain the process of distribution of compressed air with diagram.
Answer
Sign in to view the complete answer paper.
Explain the application of compressed air, in Mining machinery.
Answer
Sign in to view the complete answer paper.
Explain the maintenance of compressed air and distribution systems.
Answer
Sign in to view the complete answer paper.