STUPIDSID
Solve any one question from Q.1(a,b) &Q.2(a,b)
1(a)
Explain the effective load on helical gear tooth. How to estimate the effective load of helical gear tooth.
4 M
1(b)
A pair of spur gear with 20° full depth involute teeth consists of 20 teeth pinion meshing with 60 teeth internal gear. The pinion shaft is coupled to 7.5 KW electric motor running at 1440 rpm. The velocity factor is 1.5 and service factor is 1.25. Both the pinion and gears are made of alloy steel having Sut 1500 N/mm2. The module and face width are 3 mm and 30 mm respectively. The gears are finish to meet the specifications of grade-8. The dynamic load accounted by Buckingham eqation is 8500 N. Calculate the factor of safety against bending failure.
6 M
2(a)
A pair of parallel helical gear consisting of 18 teeth pinion meshing with 63 teeth gear. The pinion rotates at 1440 rpm. The normal pressure angle is 20° while the helix angle is 23°. The face with is 30 mm and the normal module is 3 mm. The pinion and gear are made of plain carbon steel 40C8 (Sut=600 N/mm2). The service factor and factor of safety are 1.5 and 2.0 respectively. Assume that the velocity factor accounts dynamic load. Caluclate the power transmitting capacity of the gears.\[C_{v}= 5.6/5.6+\sqrt{v}\]
6 M
2(b)
Obtain the expression for ratio factor used in wear strength equation of bevel gear.
4 M
Solve any one question from Q.3(a,b) &Q.4(a,b)
3(a)
Explain formative number of teeth in helical gear. Derive an expression for formative number of teeth for helical gear.
4 M
3(b)
An electric motor running at 1500 rpm is directly coupled to a shaft of 25mm diameter, which is supported by two cylindrical roller bearings. The shaft transmits power to another line shaft through flat pulley of 200 mm diameter, which is placed midway between two bearings. The tension on tight and slack side of belt is 4980 and 1660 N respectively. The belt is horiziontal. The load factor is 1.4. If the expected life of the bearing is 40000 hours. Find the dynamic load carrying capacity of the bearing, so that bearing can be selected from the manufacturer's catalog.
6 M
4(a)
Explain force anlysis of bevel gear with neat sketch.
4 M
4(b)
A deep groove ball bearing is to be selected for the following: It is subjected to varying cyclic load as listed in the table. The expected life of Bearing at 90% reliability is 13000 hours. Assume radial load factor as 0.56 and the axial load factor as 1.2. Find the euivalent Dynamic radial load acting on bearing.
| Fraction of Cyle | Type of load | Radial (N) | Axial(N) | Speed(RPM) | Shock and service factor |
| 1/6 | Heavy shock | 3500 | 1300 | 600 | 2.5 |
| 2/6 | Moderate shock | 2800 | 1100 | 700 | 2 |
| remaining | Light shock | 2200 | 900 | 800 | 1.2 |
6 M
Solve any one question from Q.5(a,b,c) &Q.6(a,b)
5(a)
Write short note on thermal considerations in worm gear.
4 M
5(b)
A pair of worm and worm wheel is designed at 2/54/10/5. The worm is transmitting 6kW at 1800 rpm to a wheel. The permissible bending strength is 120 N/mm2, the wear load factor is 0.83 N/mm2, the coefficient of friction is 0.05 and normal pressure angle is 20°.
Find
i) Factor of safety in bending
ii) Factor of safety in wearing
iii) Factor of safety in heat dissipation. Use following data Lewis form factor -y' = 0.484-2.87/z', and Barth factor =\( \frac{6}{6+v}\)/ Input KW = \( \frac{a^{1.7}}{34.5\left ( i+5 \right )}\)/ Where, a = center distance, i = Gear ratio.
Find
i) Factor of safety in bending
ii) Factor of safety in wearing
iii) Factor of safety in heat dissipation. Use following data Lewis form factor -y' = 0.484-2.87/z', and Barth factor =\( \frac{6}{6+v}\)/ Input KW = \( \frac{a^{1.7}}{34.5\left ( i+5 \right )}\)/ Where, a = center distance, i = Gear ratio.
12 M
6(a)
Explain overhauling and self - locking conditions for worm gearing.
4 M
6(b)
A pair of worm gear designated as 2/52/10/4 transmit 10 kW power at 720 rpm supplied to worm shaft. The coefficient of friction is 0.04 and pressure angle is 20. Assume worm is above the worm gear and rotates clockwise direction when viewed from left. If worm is left hand, determine and show by neat sketch.
1)Component of tooth forces acting on worm and worm gear.
ii) Efficiency of worm gear.
1)Component of tooth forces acting on worm and worm gear.
ii) Efficiency of worm gear.
12 M
Solve any one question from Q.7(a,b) & Q.8(a,b,c)
7(a)
Three V-belts are to be used to transmit a power from an electric motor running at 2800 rpm to a machine at 700 rpm. The center distance between input and output shaft is 800 mm. The groove angle is 30° and the coefficient of friction between the belt and sheave is 0.5. The density of belt material is 1100 kg/m3 and allowable tensile stress for the belt material is 1.75 N/mm2. If the cross sectional area of each belt is 600 mm2 determine
i) The Pulley pitch diameter
ii) Maximum power the belt can transmit
iii) The required initial tension in each belt
i) The Pulley pitch diameter
ii) Maximum power the belt can transmit
iii) The required initial tension in each belt
12 M
7(b)
Explain the procedure for the selection of flat belt from manufacture's catalog.
4 M
8(a)
Write a note on stresses in wire rope.
4 M
8(b)
In chain drives the sprocket has odd number of teeth and chain has even number of links Why?
4 M
8(c)
A compressor running at 750 rpm is driven by an electric motor running at 1500 rpm through the 8mm×X225mm flat leather belt. The center distance is 1.5m. The coefficient of friction between the belt and pulley is 0.35 and belt mass is 900 kg per cubic meter. If the allowable tensile stress for the belt material is 2 N/mm2 determine
i) The tensions in belt
ii) Maximum power transmitting capacity of the belt.
i) The tensions in belt
ii) Maximum power transmitting capacity of the belt.
8 M
Solve any one question from Q.9(a,b,c) & Q.10(a,b)
9(a)
What is bearing characteristics number as applied to journal bearing and its significance.
4 M
9(b)
Derive Petroff's equation.
8 M
9(c)
Write notes on
i) Additive for mineral oil.
ii) Properties of bearing material.
i) Additive for mineral oil.
ii) Properties of bearing material.
6 M
10(a)
Explain Rainmondi and boyd Method.
6 M
10(b)
The following data is given for a 360° hydrodynamic bearing:
Radial load = 9KN
Unit bearing pressure = 900kPa
Clearance ratio = (r/c) = 800
Journal speed = 1440 rpm
Viscosity of lubricant = 30 mpas Assume that the total heat produced in the bearing is carried by the total oil flow and 1/d is equal to 1. Calculate dimensions of the bearing, coefficient of friciton, power lost in friction, total flow of oil, side leakage and temperature rise. Refer Table 1 for bearing data.
Radial load = 9KN
Unit bearing pressure = 900kPa
Clearance ratio = (r/c) = 800
Journal speed = 1440 rpm
Viscosity of lubricant = 30 mpas Assume that the total heat produced in the bearing is carried by the total oil flow and 1/d is equal to 1. Calculate dimensions of the bearing, coefficient of friciton, power lost in friction, total flow of oil, side leakage and temperature rise. Refer Table 1 for bearing data.
| l/d | ∈ | ho/c | S | ? | \left ( \frac{r}{c} \right )f\left ( \frac{Q}{rcn_{s}l} \right ) | \frac{Q}{Q_{s}} | \frac{P}{P_{max}} | |
| 1 | 0.1 | 0.9 | 1.33 | 79.5 | 26.4 | 3.37 | 0.150 | 0.540 |
| 0.2 | 0.8 | 0.631 | 74.02 | 12.8 | 3.59 | 0.280 | 0.529 | |
| 0.4 | 0.6 | 0.264 | 63.10 | 5.79 | 3.99 | 0.497 | 0.484 | |
| 0.6 | 0.4 | 0.121 | 50.58 | 3.22 | 4.33 | 0.680 | 0.415 | |
| 0.8 | 0.2 | 0.0446 | 36.24 | 1.70 | 4.62 | 0.842 | 0.313 | |
| 0.9 | 0.1 | 0.0188 | 26.45 | 1.05 | 4.74 | 0.919 | 0.247 | |
| 0.97 | 0.03 | 0.00474 | 15.47 | 0.514 | 4.82 | 0.973 | 0.152 | |
12 M
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