Machine Design MCQ Questions & Answers | Mechanical Engineering

Feather key is a special type of key used when one component (like a gear, pulley, or coupling) is required to slide along the shaft while still transmitting torque.

Reason: To allow axial movement, the key is made loose in the shaft so it can slide along with the component, but it is tight in the hub to ensure a firm torque-transmitting connection.

Other options:
- Tight in shaft and loose in hub would prevent sliding, defeating the purpose of a feather key.

- Tight in both shaft and hub would act like a sunk key and not allow axial movement.

- Loose in both shaft and hub would result in no proper torque transmission.

Conclusion: Therefore, a feather key is generally loose in the shaft and tight in the hub.

For pipes carrying water at low pressures, the most commonly used pipe joint is the Socket joint.

A Socket joint is simple to make and provides a tight connection suitable for low-pressure applications.

- Option A: Socket joint is widely used in plumbing for water supply lines at low pressure.
- Option B: Nipple joint is typically a short piece of pipe used to connect two fittings but is not a joint type by itself.
- Option C: Union joint is used where frequent dismantling is required, more suitable for maintenance purposes.
- Option D: Spigot and socket joint is similar to the socket joint but generally used for higher pressure or different pipe types.

Hence, the correct answer is Option A: Socket joint.