Which ONE of the following keys did the student most likely use?
Gib-Head Key: Tapered Sunk Key Identification
The question describes a specific type of sunk key used to connect a shaft to a hub in a rotating machine. The key is noted to be tapered and prevents relative axial motion. Let's analyze the options based on these properties:
Key Type Analysis
- Saddle Key: Typically rests on the shaft surface and is not sunk into a keyway. It primarily prevents rotation.
- Woodruff Key: A segment of a disk, it fits into a semicircular keyway on the shaft. While it prevents rotation, it's not primarily defined by being tapered or its ability to prevent axial motion.
- Feather Key: A type of sunk key, usually parallel (not tapered), that transmits torque but often allows for axial movement.
- Gib-Head Key: This is a type of sunk key that is tapered (commonly with a 1:100 taper). The taper prevents relative axial movement between the shaft and the hub, and the 'gib-head' aids in its removal. This matches the description provided in the question.
Conclusion
Based on the requirement for a tapered sunk key that prevents axial motion, the Gib-head key is the most suitable choice.
Correct Answer: Option D (Gib-head key)Important Questions from Keys
A key having a square cross-section of side d/4 and length l is used to transmit torque T from the shaft of diameter d to the hub of a pulley. Assuming the length of the key to be equal to the thickness of the pulley, the average shear stress developed in the key is given by
The forces experience by a Key used in a gear train for power transmission is
A key of 14 mm width, 9 mm height and 100 mm length is mounted on a shaft of 50 mm diameter. If the allowable shear stress for the key material is 50 MPa, what is the maximum torque that can be transmitted?
- A key of width and height of 6 mm each is used to fix a gear on a shaft of 20 mm diameter. The shaft is used to transmit 10 kW power at 600 rpm to the gear. Permissible shear stress in the key is 80 N/mm$^2$, while compressive stress in the key is neglected. The minimum length of the key, in mm, is _____(round off to 2 decimal places).
- Which of the following key transmits power through frictional resistance only?
