Test: Critical Speeds or Whirling of Shaft & Gear Train & Gear Design - 2 - Mechanical Engineering MCQ

Assertion (A): The critical speed of an elastic shaft calculated by the Rayleigh's method is higher than the actual critical speed.

Reason (R): The higher critical speed is due to higher damping ratio.

An epicyclic gear train is shown schematically in the adjacent figure.

The sun gear 2 on the input shaft is a 20 teeth external gear. The planet gear 3 is a 40 teeth external gear. The ring gear 5 is a 100 teeth internal gear. The ring gear 5 is fixed and the gear 2 is rotating at 60 rpm (ccw = counter-clockwise and cw = clockwise).
The arm 4 attached to the output shaft will rotate at

The danger of breakage and vibration is maximum?

Two mating spur gears have 40 and 120 teeth respectively. The pinion rotates at 1200 rpm and transmits a torque of 20 Nm. The torque transmitted by the gear is

A shaft of 50 mm diameter and 1 m length carries a disc which has mass eccentricity equal to 190 microns. The displacement of the shaft at a speed which is 90% of critical speed in microns is

The arm OA of an epicyclic gear train shown in figure revolves counter clockwise about O with an angular velocity of 4 rad/s. Both gears are of same size. The angular velocity of gear C, if the sun gear B is fixed, is

If a spring-mass-dashpot system is subjected to excitation by a constant harmonic force, then at resonance, its amplitude of vibration will be            

Whirling speed of a shaft coincides with the natural frequency of its

The sun gear in the figure is driven clockwise at 100 rpm. The ring gear is held stationary. For the number of teeth shown on the gears, the arm rotates at

Whirling speed of shaft is the speed at which

Large speed reductions (greater than 20) in one stage of a gear train are possible through

Consider the following statements

The critical speed of a shaft if affected by the
1. eccentricity of the shaft
2. span of the shaft
3. diameter of the shaft

Of these statements:

To make a worm drive reversible, it is necessary to increase

The rotor of a turbine is generally rotated at

For (ω₁ = 60 rpm clockwise (cw) when looked from the left, what is the angular velocity of the carrier and its direction so that Gear 4 rotates in counter clockwise (ccw) direction at twice the angular velocity of Gear 1 when looked from the left?

Assertion (A): Every rotating shaft has whirling speeds

Reason (R): Eccentricity of rotors on rotating shafts is unavoidable.

A 1.5 kW motor is running at 1440 rev/min. It is to be connected to a stirrer running at 36 rev /min. The gearing arrangement suitable for this application is

Consider the following statements:    

When two gears are meshing, the clearance is given by the
1. Difference between dedendum of one gear and addendum of the mating gear.
2. Difference between total and the working depth of a gear tooth.
3. Distance between the bottom land of one gear and the top land of the mating gear.
4. Difference between the radii of the base circle and the dedendum circle.

Which of these statements are correct?

Assertion (A): When one body drives another by direct contact, their contact points must have equal components of velocity normal to the surfaces at the point of contact.

Reason (R): Two points in the same body must have the same component of velocity relative to the third body, in the direction of the line joining the two points. 

The working surface above the pitch surface of the gear tooth is termed as

Match List I with List II and select the correct answer using the codes given below the lists: 

Match List I with List II and select the correct answer 

Which type of gear is used for shaft axes having an offset?  

When two shafts are neither parallel nor intersecting, power can be transmitted by using

Which one of the following pairs is not correctly matched?

The gears employed for connecting two non-intersecting and non-parallel, i.e., non coplanar shafts are

Mitre gears