University of Mumbai 2007-4th Sem M.E Mechanical Engineering Design of Power Transmission System -e - Question Paper

N.B.: (1)    Question No. 1 is compulsory.

(2)    Attempt any four questions from the remaining six questions.

(3)    Assume suitable data wherever required, giving reasons.

(4)    Draw sketches lo illustrate your answers.

(5)    Use of standard databooks such as PS(i Design Databook is permitted.

(6)    Figure* to the right indicate Tull marks.

AO*    *1K tu/r\<y~y) 1<aaa f)L

I. Answer iiny fouKofthe following :

i,a i    Explain briefly various hydraulic direction control valves.

(b)    Advantages and disadvantages of pneumatic power and control systems.

(c)    Write short note on FR1. unit.

(d)    Draw hydraulic circuits showing pressure relief value, pressure reducing value, sequence value, pressure unloading valve and back pressure valve indicating their functions.

(e)    lixplain the use of flexible power transmission elements. State merits and demerits.

2. (a) Design a cliain drive to transmit 5*5 kW power from an electric motor rotating at 725 RPM lo an ail 11) biover operating at 250 RPM. The drive operates continuously 24 hrs/day. Draw dimensioned sketches.

(b) For the abcve application if v-belt drive is used, selecting suitable belt secrion and pulley materials. 10 design and sketch the drive.

3. Following clatii rclalos to the trolley travel mcchanism of an EOT crane :

Weight of trolley including load to be lifted 140 kN Tractive zffort    = 28 N/kN

Trolley wheel diameter    * 320 mm

Trolley travel speed    = 30 m/min

Application    ~ Class J1

(a)    Select suitable trolley tiavel motor including type, power .speed and other specifications. Suggest suitable 10 power transmission system giving brief descrption of the elements like type, nomber of stages, reduction ratio etc. Draw a neat schematic diagram of the drive with preliminary details of the drive elements including brake and clutch if used

(b)    Choosing suitable type, design and sketch the brake for the above mechanism.    10

4.    (a) Design a pneumatic control system to operate two sliding doors simultaneously (open or shut) by two JO

pneumatic cylinders cither from inside or from outside using push buttons, fly pressing the same or the other push buttoin alternately the doors should open or close as the case may be. Draw ihe circuit diagram with specifications of components. Explain working.

(b) De<igna fully automatic pneumatic control system to operate two cylinders in sequence. The first piston 10 should move forward followed by Ihe second cylinder piston to move forward. When the second piston is fullcy forward, the first piston should retract, followed by the second piston. The next cycle should be initialed automatically by the last operation of the previous cycle. Draw the circuit diagram, labelling the components with specifications. Explain the working.

5.    (a) A hydraulic cylinder has a bore 125 mm, rod diameter 70 mm. It drives a mass of 2 tonnes vertically up and 10

down at a maximum speed of 2 m/s. I he lift speed is set by adjusting the putnp dispalcement and the rctract speed by How control valve. The load is slowed down to rest in the cushions length of 40 mm. If the relief valve is set at 140 bar, determine the average pressure in the cushion on extend and retract strokes.

(b) A mass of 2 tonnes is to be accelerated vertically up and down upto a velocity of 2 m/s from rest over a 10 distance olSO mm. Friction in guides is 10 percent of load lifted. Calculate the bore of cylinder required if tf e maximum allowable pressure at full bore is 120 bar. The seal friction equals to pressure drop of 5 bar and back pressure 5 bar. Select suitable type and si/c pump and draw circuit diagram.

M' Ir-T Np <rq[t_G#r,yin TV~rrOC, JUri * kwa- '

Con.3347-BB-16S047. '     _r    X 1 , 7 i

6,    A hydraulic cylinder has to operate with following cycle:    20

(a)    extend 135 mm at 3D bar in 6 sec.

(b)    extend 15 mm at 200 bar in 4 see.

(c)    temaiit extended at 200 bar for 20 see.

(d)    retract 150 mm at 30 bar in 5 see.

(e)    remain retracted for 15 see.

Cylinder diameter is 200 mm. piston rod diameter 120 mm and stroke 150 mm. Draw displacement, now and pressure diagrams.

(i)    Design arul ;maly*e hydraulic system using two fixed discharge pumps.

(ii)    Design and analyse hydraulic system using a single fixed dispalcement pump and an accumulator,

7.    (a) Dcsigna WomiandWorm-geardriveforabeltconvc>'ordriverfromanelcctricmotorof30kWat I450RPM. |3

The reduction ratio is 25.

(b) Explain with a neat sketch the working of any one hydraulic motor.    7

Attachment: university-of-mumbai-2007-m-e-mechanical-engineering-51637-1.pdf

Earning:   Approval pending.