1) Which of the following gear tooth failures is/are induced when maximum Hertz contact stress on gear tooth surface exceeds surface endurance strength of tooth?
a. Abrasive strength
b. Corrosive wear
c. Destructive pitting
d. Galling
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2) What is Scuffing?
a. Lubrication failure
b. Surface fatigue failure
c. Surface injury on matting teeth surfaces
d. Wear due to chemical action by lubricants
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3) What is the deformation or dynamic factor if sum of errors on meshing teeth of steel pinion and gear is 32 x 10-3 mm?
a. 284.8 N/mm
b. 300.23 N/mm
c. 320.5 N/mm
d. 368 N/mm
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4) If (σb x Y)pinion > ( σb x Y)gear then ________ is designed for bending.
a. pinion
b. gear
c. both a. and b.
d. none of the above
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5) What is the load stress factor for cast iron gear pair if BHN = 300?
a. 1.89 N/mm2
b. 1.62 N/mm2
c. 1.44 N/mm2
d. 1.413 N/mm2
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6) Angle made by ________ with axis of rotation is called as helix angle.
a. only helix
b. only teeth
c. helix or teeth
d. none of the above
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7) What is the minimum face width required for a helical gear which has helix angle of 23o and normal module of 7?
a. ≥ 64.72
b. ≥ 56.28
c. ≥ 33.35
d. ≥ 8.74
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8) Which of the following formulae is used to determine minimum number of teeth required on helical pinion to avoid interference?
a. (2ha cos3 Ψ) / (mn sin2 Φn)
b. (mn zp / 2 cos Ψn)(1+G)
c. 1.15 π mn / sin Ψn
d. None of the above
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9) To avoid interference the minimum number of teeth required on helical pinion decreases as helix angle ________
a. decreases
b. increases
c. does not affect number of teeth
d. none of the above
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10) Which of the following statements is/are true?
a. Helical gears have high contact ratio than spur gears
b. Axial thrust is created by helical gears on bearings
c. Crossed helical gears are used for power and motion transmission
d. All of the above
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11) A bevel gear has pitch circle diameters of pinion and gear as 20 mm and 40 mm respectively. What is the face width of bevel gear?
(m =module)
a. 17.5 m
b. 10 m
c. 7.45 m
d. 3.16 m
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12) What is the pitch line velocity if pinion has pitch circle diameter of 35 mm and rotates at 1000 r.p.m transmitting power of 250 kW to the gear?
a. 1.832 m/s
b. 2.5 m/s
c. 3.662 m/s
d. none of the above
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13) A bevel gear consists of steel pinion and cast iron gear having pitch line velocity of 10 m/s. The maximum tangential force acting on the gear is 1500 N and face width is 40 mm. What is the dynamic load acting on this single stage bevel gear box if sum of errors on meshing teeth is 10 x 10-3 N/mm? (Use Buckingham's equation)
a. 4000.12 N
b. 4064.58 N
c. 2500.23 N
d. 2000.10 N
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14) A bevel gear made of steel pinion and steel gear has dynamic factor C equal to __________
a. 8900 e
b. 10000 e
c. 11500 e
d. 15000 e
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15) A straight bevel gear is manufactured by cutting process and maximum tangential force of 12000 N acts on it. What is the effective load acting between meshing teeth if pitch line velocity is 130 m/s?
a. 92.30 kN
b. 272 kN
c. 2000 N
d. Insufficient data
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16) A deep groove ball bearing rotating at 1200 r.p.m. is subjected to radial and an axial force of 2000 N and 1500 N respectively. What will be the basic dynamic capacity of bearing if 20,000 hours is the rating life?
(Consider radial factor = 0.55, Thrust factor = 2 & application factor = 1.5?
a. 69.448 kN
b. 54.498 kN
c. 50.236 kN
d. 12.726 kN
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17) Load acting on bearing in its plane of rotation is called as __________
a. axial load
b. radial load
c. thrust load
d. none of the above
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18) Which of the following elements is not used as a roller in roller bearings?
a. Cylindrical
b. Taper
c. Spherical
d. None of the above
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19) Which of the following bearings carry thrust load in one direction?
a. Spherical roller thrust bearings
b. Taper roller bearings
c. Both a. and b.
d. None of the above
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20) A cylindrical roller bearing is subjected to radial force of 4500 N and application factor 1.3. What is the equivalent dynamic load acting on bearing if it has 90% reliability with desired life of 10000 hrs?
a. 3461.53 N
b. 5000 N
c. 5850 N
d. Insufficient data
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21) A worm gear pair has 2 starts on worm thread, 11.2 as diametral quotient, 2 as module and 38 number of teeth on worm gear. How is the gear pair designated with these specifications?
a. 2/11.2/38/2*
b. 11.2/2/38/2
c. 2/38/2/11.2
d. 2/38/11.2/2
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22) What is the shortest distance between worm gear and axes of the worm for a worm gear pair designated as 2/40/10/8?
a. 50 mm
b. 200 mm
c. 320 mm
d. 360 mm
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23) If pressure angle is 22o and coefficient of friction is 0.05. What is the axial force acting on the worm gear designated as 1/40/10/5, if tangential force of 1200 N acts on it?
a. 1241.2 N
b. 2618.4 N
c. 7755.1 N
d. 7847.4 N
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24) What is the axial force acting on a worm gear for a worm gear pair 1/40/9.5/10, if tangential and axial force of 6213 N and 9236 N act respectively on the worm? ( Φn = 25o & μ = 0.04)
a. 6213 N
b. 9263 N
c. 3050 N
d. Insufficient data
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25) A gear box having surface area of 0.30 m2 has overall heat transfer coefficient of 23 W/m2 oC,when a fan is mounted on worm shaft to circulate air on fins. What is the power transmitting capacity of a gear box based on thermal considerations, if temperature rise of lubricating oil is 50 oC? (Assume λ = 6o, Φn = 22o & μ = 0.05)
a. 1.023 kW
b. 1.006 kW
c. 1.227 kW
d. 2.000 kW
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26) Which of the following statements is/are true for V-belts?
a. V-belt drives have low reduction ratio
b. Due to wedging action slip is negligible in V-belts
c. V-belt transmits power over long centre distances
d. All of the above
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Answer
Explanation
Related Ques
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ANSWER: Due to wedging action slip is negligible in V-belts
Explanation:
No explanation is available for this question!
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27) A V-belt pulley transmits power to flat belt pulley. If the coefficient of friction is 0.25 then which pulley governs the design? (β = 21o & α = 0.2)
a. Flat pulley
b. V-belt pulley
c. Both a. and b.
d. None of the above
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28) A V-belt pulley has belt velocity 20 m/s and mass 0.7 kg per meter. If allowable tension in the belt is 600 N then what will be the power transmitting capacity of belt?
(Assume μ = 0.5 & θ = 2.5 rad)
a. 3.75 kW
b. 3.2 kW
c. 4.5 kW
d. 5.23 kW
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29) Lang lay ropes offer more resistance to __________
a. fatigue failure
b. abrasive failure
c. both a. and b.
d. none of the above
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30) What does number 6 indicate in the class of wire rope 6 x 37 (18/12/6/1)?
a. Diameter
b. Strands
c. Wires
d. None of the above
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31) A journal of 120 mm diameter rotates in a bearing at a speed of 1000 rpm. What is the power lost during friction if 8 kN radial load acts on the journal and coefficient of friction is 2.525 x 10-3?
a. 0.126 kW
b. 0.253 KW
c. 2.365 kW
d. 7.615 kW
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32) Lubricating oil of mass density 800 kg/m3 used in 360o hydrodynamic bearing has a flow rate of 6000 mm3. Neglecting side leakage if temperature rises to 10 oC and specific heat is 1.55 kJ/kg oC, what is the rate of heat dissipated in the bearing?
a. 7.4 W
b. 236 W
c. 0.236 kW
d. 0.0744 kW
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33) Lubricating oil used in hydrodynamic bearing has total flow rate of 0.340 l/min and side leakage of 0.1520 l/min. If mass density of oil is 600 kg/m3 and specific heat is 1.05 kJ/kg oC, what is the rise in temperature if power lost in friction is 0.05 kW?
a. 11.23o C
b. 15.11o C
c. 18.03o C
d. 22.23o C
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34) Which of the following formula is used to calculate oil-film thickness in hydrodynamic bearings?
a. h = (c + Є cos θ)
b. h =(c – Є cos θ)
c. h = c (1+ Є sin θ)
d. h = c (1+ Є cos θ)
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35) Determine the Sommerfeld number considering the following data for hydrodynamic bearing?
1. Diameter of bearing = 120 mm
2. Bearing pressure = 5 N/mm2
3. Oil viscosity = 30 cP
4. Journal speed = 900 rpm
5. Radial clearance = 150 microns
a. 0.2360
b. 0.0144
c. 0.0115
d. 0.0178
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