What is a saddle key provided for?

• A. In the hub only and hollowed to fit the shaft
• B. Has flat surface and is planned off
• C. Withstands torsion in one direction only
• D. Fits in a sunk key-way parallel to the axis

Answer: (A)

A saddle key is designed specifically to fit onto a shaft and is often secured in a manner that allows it to transmit torque effectively. The unique feature of a saddle key is that it is hollowed out in the middle, which allows it to sit firmly on the shaft while fitting snugly into the hub, thus ensuring a stable connection. This design allows the key to engage properly within the keyway of the hub, which is critical for its function in power transmission.

By properly fitting into the hub, the saddle key enables efficient torque transfer between shafts and attached machinery components. Additional benefits include the ability to accommodate slight misalignments during operation, reducing the risk of damage or wear. Thus, its specific structure serves a vital role in mechanical systems where reliable motion and force transfer are essential.