Question Paper: Hydraulics and Pneumatics : Question Paper Dec 2015 - Mechanical Engineering (Semester 5) | Pune University (PU)
0

## Hydraulics and Pneumatics - Dec 2015

### Mechanical Engg (Semester 5)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS
(1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks.

### Solve any one question from Q1 and Q2

1 (a) State any two governing laws of fluid and explain any one in detail.(6 marks) 1 (b) Draw and explain a circuit for Accumulator as a shock absorber.(6 marks) 1 (c) A hydro static transmission operating at 70 bars has the following.
Find:
i) Displacement of motor,
ii) motor output torque.

 Pump Motor Vd = 84 cm3 Vd = ?, Ta=? Volumetric efficiency = 82% Volumetric efficiency = 92% Mechanical efficiency = 88% Mechanical efficiency = 90% N= 600 rpm N= 500 rpm
(8 marks) 2 (a) Enlist six different specific applications of pneumatic system.(6 marks) 2 (b) Draw neat sketches of three different types of seals, and state the various sealing materials?(6 marks) 2 (c) A 25000 N weight is being pushed up on an inclined surface by a cylinder, as shown in Figure 2c. The coefficient of friction between the weight and the inclined surface equals 0.16. For the pressure of 7000 kPa, determine -
i) The required cylinder piston diameter, if the weight is being pushed at a constant speed.
ii) The required cylinder piston diameter, if the weight is to accelerate from 0 mm/s to 1500 mm/s in 0.5 s.

(8 marks)

### Solve any one question from Q3 and Q4

3 (a) Draw ISO symbols for any three different methods of DCV actuation, and state one application of each.(6 marks) 3 (b) Explain with neat sketch bleed off circuit.(6 marks) 3 (c) Draw a neat sketch of Pump unloading circuit and explain its working.(6 marks) 4 (a) Explain with neat sketch working of pressure reducing valve. Draw an ISO symbol of it.(6 marks) 4 (b) Explain with neat sketch cylinder synchronization circuit with two cylinders connected in parallel.(6 marks) 4 (c) Draw a neat sketch of Riveting circuit and explain its working.(6 marks)

### Solve any one question from Q5 and Q6

5 (a) Explain the working of Quick Exhaust Valve with a neat sketch.(6 marks) 5 (b) Draw a throttle-out circuit used in pneumatics.(6 marks) 5 (c) Differentiate between hydraulic and air motor.(4 marks) 6 (a) Explain the application of AND Valve with a typical circuit.(6 marks) 6 (b) Sketch compressed air generation and distribution system.(6 marks) 6 (c) State any four applications of pneumatics in automobile industry explain any one in detail.(4 marks)

### Solve any one question from Q7 and Q8

7 In a semi-automatic machine, a double acting hydraulic cylinder has a reciprocating motion. The forward motion is obtained using a regenerative circuit. The load during the forward stroke is 10 kN. The total stroke of 60 cm is to be completed in about 5 sec. The return speed is to be as fast as possible. Draw a hydraulic circuit to achieve the given objective. Select different components you have used in the circuit from the data given. Mention ratings of the components in case it is not available in the given Data.(16 marks) 8 (a) A hydraulic cylinder is used to push the object on a smooth surface. The total load on the hydraulic cylinder during forward stroke is 15.5 kN. The object has to be pushed at a distance of 500 mm in about 7 sec. The load during the retraction stroke is negligible, and it is to be retracted as fast as possible. Provision is required to hold the cylinder anywhere in between the end positions. Draw a simple hydraulic circuit, using Meter-in speed control method, to fulfill the given objective. Select different components from the data given. Specify ratings of the components in case it is not available in the given data.(10 marks) 8 (b) Analyze the circuit shown in Figure 8b.

(6 marks)