Mechanical Quiz 14 June

Which gear type produces the quietest operation due to gradual tooth engagement?

• Spur gear

• Helical gear

• Bevel gear

• Worm gear

Two gears of the same module are in mesh. If one gear has double the number of teeth, what happens to the speed?

• Doubled

• Halved

• Same

• Cannot determine without pressure angle

Which of the following statements about worm gears is true?

• They are used for parallel shafts

• They always provide a speed increase

• They allow self-locking under certain conditions

• They produce less friction than spur gears

Which of the following gear train types is best suited for achieving a large speed reduction in a compact space, and can have both input and output shafts on the same axis?

• Simple gear train

• Compound gear train

• Reverted gear train

• Epicyclic (planetary) gear train

A spur gear pair with involute teeth is transmitting power under standard conditions. If the pressure angle ϕ is increased from 20 to 25 degree while keeping the module and number of teeth constant, which of the following is most correct regarding the implications on gear performance?

•  The base circle radius increases, and the gear becomes more compact, reducing backlash.

• The contact ratio decreases, resulting in increased noise and reduced smoothness.

• The radial force component decreases, reducing bearing loads but increasing sliding.

• The tooth becomes thinner, increasing the load-carrying capacity and durability.

In belt drives, what causes “creep”?

• Uneven belt tension due to elongation

• Excessive torque

• Slipping between belt and pulley

• Lack of lubrication

In belt drives, which of the following would increase slip?

• Increased belt tension

• Using a V-belt instead of a flat belt

• Decreased pulley diameter

• High coefficient of friction between belt and pulley

In a belt drive system, the driver pulley has a diameter of D1=500 and the follower pulley has a diameter of D2=250 mm. If the driver rotates at N1=300 RPM, and the belt is crossed, which of the following correctly gives the velocity ratio and direction of rotation of the driven pulley?

• Velocity ratio : N1/​N2​​=D1​/D2​​, rotation is same as driver

• Velocity ratio: N1/​N2​​=D2​/D1​​, rotation is same as driver

• Velocity ratio: N1​/N2​​=D2​/D1​​, rotation is opposite to driver

• Velocity ratio: N1/​N2​​=D1​/D2​​, rotation is opposite to driver

Compared to belt drives, which of the following is a true advantage of chain drives in power transmission systems?

• They provide negative (slip) drive and non-constant velocity ratio

• They provide negative (slip) drive and constant velocity ratio

• They provide positive (non-slip) drive and non-constant velocity ratio

• They provide positive (non-slip) drive and constant velocity ratio

Which of the following best describes the main advantage of a Continuously Variable Transmission (CVT) system compared to traditional gear-based transmissions?

• It increases fuel consumption due to constant high RPM operation

• It allows seamless variation of gear ratio, optimizing engine performance

• It uses fixed gear ratios to provide high torque output

• It is limited to use only in low-speed, low-power applications