Section-A

Attempt All questions.

1.   Spur and helical gears transmit power between two

(a). Parallel shafts with intersecting axis (b).Parallel shafts

(c). Both (a) & (b)                        (d).None of these

2.   The helix angle for single helical gears ranges from

(a). 10° to 15°                                    (b).15° to 20°

(c). 20° to 35°                                    (d).35° to 50°

3. What is the pitch cone distance of bevel gear, if pitch circle diameter of bevel pinion and gear is 20 and 30 respectively?

(a). 100 mm                                      (b).18.02 mm

(c). 21.32 mm                                   (d).25 mm

4.   If tangential force on worm is 1500N, then axial force on worm wheel will be?

(a). 1500 N                                        (b).3000 N

(c). 1500√2 N                                    (d).750 N

5.   The following is not a type of sliding contact bearing

(a). Journal bearing                           (b). Bush bearing

(c). Thrust bearing                            (d).Ball bearing

6. The rolling element bearings are

(a). Hydrostatic bearing                    (b).Squeeze film bearing

(c). Anti-friction bearing                   (d). Grease lubrication bearing

7.   Deep groove ball bearing are used for

(a). Heavy thrust load only                (b). Radial load at high speed

(c). Small angular displacements of shafts  (d). Combined thrust and radial loads at high speed

8. What is the function of gudgeon pin?

(a). Acts as stiffeners                        (b).Supports piston head

(c). Connects piston to connecting rod (d).All of the above

9. In a full journal bearing, the angle of contact of the bearing with the journal is

(a). 120⁰                                           (b).180⁰

(c). 270⁰                                           (d).360⁰

10. If diameter of cylinder of bore is 120mm, then thickness of the cylinder will be

(a). 7 mm                                          (b).12 mm

(c). 6 mm                                         (d).Information not sufficient

Section-B

 Attempt anyEight questions from this section.

1. A compressor running at 250 rpm is driven by a 15 kW, 750 rpm electric motor through a pair of 20 ⁰ full depth spur gears. The pinion is made of 55C8 steel (heat treated) and gear of 40C8 steel (untreated). How do you decide to select between pinion and gear to design.

2. Two helical gear of 20 teeth and 40 teeth have paired at a centr e distance of 10 cm. If the helix angle of gear is 10 ⁰, what is the module of gear pair?

3. Listed the design procedure of bevel gear for dynamic tooth load.

4. For a hardened steel worm and gear the centre distance is 480 mm. Transmission ratio is 20. Find th e axial module and lead angle.

5.  Design a journal bearing to support a load of 4 KN at 500 rpm, using a hardened steel journal and a bronze backed Babbitt bearing. Take room temperature as 20⁰C and operating oil temperature as 70 ⁰C.

6. Design a journal bearing for a centrifugal pump from the following data:

Load on the journal = 20 KN

Speed of the journal = 1000 rpm

Absolute viscosity of oil at 55 ⁰C = 0.017 Kg/m-s

Operating temperature = 55 ⁰C

Ambient temperature of oil = 16 ⁰C

Maximum bearing pressure for t he pump = 1.5 N/mm²

7. Select a suitable bearing which is to operate at 600 rpm and is acted upon by 2000 N radial load and 500 N thrust load. The inner ring rotates, the load is steady and the service is continuous. The shaft diameter, from strength consider ation is 50 mm and the life expectancy is 12000 hrs. at reliability of 95%.

8. A shaft rotating at 1500 rpm is supported by two bearings. The forces acting on each bearing are 8 KN radial load and 5 KN axial thrust. If the shaft diameter is 45 mm and the expected life of bearing is 500 hours, suggest a suitable bearing for the application.

9. Find the thickness of the piston head, If a cast iron piston for a single acting 4-stroke diesel engine for the following data:

Cylinder bore = 100 mm ; Stroke = 120 mm ;

Speed = 2200 rpm

Fuel consumption = 0.227 kg/kW/h ; Maximum gas pressure = 5 N/mm ²; Allowable temperature difference = 222 ⁰C. Break mean effective pressure = 0.65 N/mm ²;

Thermal conductivity for cast iron = 46 J/s m² - ⁰C/m

10. What is the procedure for the design of an I.C. engine cylinder?

Section-C

Attempt any two questions from this section.

1. A pair of spur gear with 20 ⁰ full depth involute teeth consists of a 20 teeth pinion meshing with a 40 teeth gear. The pinion is mounted on a crankshaft of 7.5 kW single-cylinder diesel engines running at 1500 rpm. The driven shaft is connected to a two stage compressor. The pinion and gear are made of 40C8 steel (S_ut=600MPa). The module and face width of the gear are 4 mm and 40 mm respectively. If the gear are manufactured to Grade 8, Determine dynamic load for pinion.

Take:v_p=6.30 m/s ; (F_t)_max= 1790 N

2. A journal bearing has a journal diameter of 50 mm and the diameter of the bushing is 50.1 mm. The bushing is 50 mm long and has to support a load of 1 kN at a speed of 1200 rpm. Determine the minimum oil film thickness and power loss for SAE 10 oil. Assumi ng the oil film temperature to be 70 ⁰C.

Select a single row deep groove ball bearing for radial load of 4.5 KN and axial load of 5.5 KN operating at speed of 1500 rpm, for an average life of 5 years running for 12 hours per day. Inner race revolves and load is with light jerks.