Theory Of Machine MCQ Questions & Answers | Mechanical Engineering

The train value of a gear train is equal to the velocity ratio of a gear train.

Train Value: This is the measure of how the rotational speed changes from one gear to another in the gear train. It is defined as the product of the gear ratios of all the gears in the train.

Velocity Ratio: The ratio of the angular velocities of the driving gear to the driven gear in a gear train. It is the reciprocal of the gear ratio, but when calculating the overall effect in a series of gears, it directly reflects the train value.

Always greater or less than unity: The train value or velocity ratio can be greater than, less than, or equal to unity depending on the configuration of the gear train. The key point is that the train value equals the velocity ratio.

The correct answer is Option A: Bevel gear.

In automobiles, the power is transmitted from the gearbox to the differential through a bevel gear. Bevel gears are specially designed gears with tapered and conical-shaped teeth that allow the transmission of power at right angles. In this context, they are commonly used in the drivetrain to transfer power from the gearbox to the differential, which further distributes power to the wheels.

Option B: Universal joint is incorrect because universal joints are typically used to transmit power at variable angles, not specifically from the gearbox to the differential.

Option C: Hooke's joint is incorrect as Hooke's joint is another term for a universal joint, which is not the primary component in the described power transmission.

Option D: Knuckle joint is incorrect as knuckle joints are not used for transmitting power in the drivetrain of automobiles.